10.1 Network Stability 10.

1 Network Stability
Electrical Network Stability Electrical Network Stability

APPS APPS

Olivier Richardot Olivier Richardot

Issue A1 Issue A1
Last modification : march 2011 Last modification : march 2011

Summary
y Summary
y

Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling
Parameters affecting transmitted power Parameters affecting transmitted power
Risky situations Risky situations
Black-Outs Black-Outs
Studies to be carried out Studies to be carried out
Application: case studies Application: case studies
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 Introduction: Issues and definitions Introduction: Issues and definitions
Theoretical reminder Theoretical reminder
R
Regulators
l t modeling
d li R
Regulators
l t modeling
d li
Parameters affecting
g transmitted p
power Parameters affecting
g transmitted p
power
Risky situations Risky situations
Black-Outs
O Black-Outs
O
Studies to be carried out Studies to be carried out
Application: case studies Application: case studies

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Problematic: stabilityy issues Problematic: stabilityy issues

● An electrical energy network is a complex structure system, made of a ● An electrical energy network is a complex structure system, made of a
certain amount of production units, interconnected through transmission certain amount of production units, interconnected through transmission
and distribution grids and distribution grids

● This system is normally in a given equilibrium state: it is said in ● This system is normally in a given equilibrium state: it is said in
synchronous operation synchronous operation

● In particular
particular, fundamental equilibrium between production and ● In particular
particular, fundamental equilibrium between production and
consumption must be ensured in terms of : consumption must be ensured in terms of :

● ACTIVE POWER (linked to the network frequency) ● ACTIVE POWER (linked to the network frequency)

● REACTIVE POWER (linked to the network voltage map) ● REACTIVE POWER (linked to the network voltage map)

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Problematic: stabilityy issues Problematic: stabilityy issues

An electrical network in equilibrium state, i.e. in a given An electrical network in equilibrium state, i.e. in a given
steady state, is permanently subject to disturbances of any steady state, is permanently subject to disturbances of any
kind kind

● occasional or discontinue disturbances: ● occasional or discontinue disturbances:

● electrical faults: short-circuit, isolation fault, … ● electrical faults: short-circuit, isolation fault, …
● operations: line opening, equipment connection, ... ● operations: line opening, equipment connection, ...

● disturbances linked to normal operation: ● disturbances linked to normal operation:

● load
l d variations
i ti ● load
l d variations
i ti
● static converters operation ● static converters operation
● ... ● ...

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Problematic: stabilityy issues Problematic: stabilityy issues

● Network parameters that can be affected (energy quality): ● Network parameters that can be affected (energy quality):

P Power P Power

U Voltage U Voltage

F Frequency F Frequency

HDR Harmonics HDR Harmonics

● Possible consequences : ● Possible consequences :

●Flicker (fast voltage variation) ●Flicker (fast voltage variation)
●Unbalances of 3 3-phase
phase system ●Unbalances of 3 3-phase
phase system
●Energy delivery cuts due to protections actions (loss of synchronism, ●Energy delivery cuts due to protections actions (loss of synchronism,
power swing, fault, …) power swing, fault, …)

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Problematic: stabilityy issues Problematic: stabilityy issues

● The basic questions to be answered by network stability studies are the ● The basic questions to be answered by network stability studies are the
following: following:

●what happens during a disturbance (voltage and frequency drift, ●what happens during a disturbance (voltage and frequency drift,
protections tripping, …)? protections tripping, …)?
●what will be the new operation point after
f the disturbance has ●what will be the new operation point after
f the disturbance has
disappear? disappear?

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Definitions and terminology

gy Definitions and terminology
gy

●Steady state ●Steady state

It is the network operation mode where all r.m.s. electrical values can be It is the network operation mode where all r.m.s. electrical values can be
considered as constant considered as constant

●Synchronous
Synchronous operation ●Synchronous
Synchronous operation
A synchronous machine connected to other synchronous machines through A synchronous machine connected to other synchronous machines through
electrical network is said in synchronous operation with the rest of the electrical network is said in synchronous operation with the rest of the
network if its electrical speed is equal to the network’s
network s voltage frequency at network if its electrical speed is equal to the network’s
network s voltage frequency at
connection node, or to other machines’ electrical speed connection node, or to other machines’ electrical speed
An electric network is said in synchronous operation if all connected An electric network is said in synchronous operation if all connected
machines are in synchronous operation with the network and between machines are in synchronous operation with the network and between
together together

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Paul Bourotte’s ‘quintuplette’
q p ((1897)) Paul Bourotte’s ‘quintuplette’
q p ((1897))

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Definitions and terminology

gy Definitions and terminology
gy

●Power swing ●Power swing

A generator is in power swing situation when mechanical values are A generator is in power swing situation when mechanical values are
s bjected to sustained
subjected s stained oscillations of finite amplit
amplitude
de aro
around
nd a stead
steady state s bjected to sustained
subjected s stained oscillations of finite amplit
amplitude
de aro
around
nd a stead
steady state
point point
The generator’s specific r.m.s. electrical values are then also subjected to The generator’s specific r.m.s. electrical values are then also subjected to
th
these oscillations
ill ti th
these oscillations
ill ti

●Static stability,
stability or small-signal
small signal stability ●Static stability,
stability or small-signal
small signal stability
An electric network is said in static stability conditions if, after a small An electric network is said in static stability conditions if, after a small
disturbance, it reaches a new steady state very close to initial steady state disturbance, it reaches a new steady state very close to initial steady state
A smallll di
disturbance
t b iis a di
disturbance
t b ffor which
hi h lilinearization
i ti off th
the system’s
t ’ A smallll di
disturbance
t b iis a di
disturbance
t b ffor which
hi h lilinearization
i ti off th
the system’s
t ’
equations is still justified equations is still justified

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Definitions and terminology
gy Definitions and terminology
gy

●Transient stability ●Transient stability

An electric network is said in transient stability relatively to a large An electric network is said in transient stability relatively to a large
dist rbances cycle
disturbances c cle if it comes across a ne
new ssynchronous
nchrono s operation stead
steady dist rbances cycle
disturbances c cle if it comes across a ne
new ssynchronous
nchrono s operation stead
steady
state after the disturbance cycle state after the disturbance cycle
A large disturbance is a disturbance for which linearization of the system’s A large disturbance is a disturbance for which linearization of the system’s
equations
ti is
i nott justified
j tifi d any more equations
ti is
i nott justified
j tifi d any more

●Conditional stability ●Conditional stability

An electric network is said in conditional stability situation when its stability An electric network is said in conditional stability situation when its stability
is due to predefined and appropriate regulators’ action is due to predefined and appropriate regulators’ action

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Different kinds of stabilityy Different kinds of stabilityy

ELECTRICAL NETWORKS’ STABILITY ELECTRICAL NETWORKS’ STABILITY
Ability to keep the system in equilibrium conditions Ability to keep the system in equilibrium conditions
Equilibrium between opposite forces Equilibrium between opposite forces

ANGLE TENSION ANGLE TENSION

synchronism maintaining voltage maintaining synchronism maintaining voltage maintaining
torques equilibrium reactive powers equilibrium torques equilibrium reactive powers equilibrium

Transient Mid and long Large voltage Transient Mid and long Large voltage
stability terms stability disturbances stability terms stability disturbances
Large disturb.
disturb Large disturb.
disturb

Small signal Small signal

stability Small voltage stability Small voltage
Steady state disturbances Steady state disturbances
P/ - relations Steady state P/ - relations Steady state
P/Q - V relations P/Q - V relations
Non-oscillatingg Oscillating instabilities Non-oscillatingg Oscillating instabilities
instabilities Insufficient damping instabilities Insufficient damping
Insufficient synchro. torque Unstable control Insufficient synchro. torque Unstable control
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Mid and long
g terms stability
y Mid and long
g terms stability
y

●Slow phenomenon ●Slow phenomenon

● Mid term stability: ● Mid term stability:

●high amplitude frequency and/or voltage drifts ●high amplitude frequency and/or voltage drifts
●typical study duration of few minutes ●typical study duration of few minutes

● Long term stability : ● Long term stability :

●uniform system frequency ●uniform system frequency
●typical study duration of tens of minutes ●typical study duration of tens of minutes

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Transient stabilityy Transient stabilityy

●High amplitude phenomenon ●High amplitude phenomenon

● Machine internal angle transient stability: ● Machine internal angle transient stability:
●large disturbances ●large disturbances
●fast dynamics (first aperiodical oscillations) ●fast dynamics (first aperiodical oscillations)
●typical study duration of few seconds ●typical study duration of few seconds

● Voltage
V lt transient
t i t stability
t bilit : ● Voltage
V lt transient
t i t stability
t bilit :
●large voltage disturbances ●large voltage disturbances
p , loads dynamics,
●events like operations, y , on load tap-changers,
p g , etc. p , loads dynamics,
●events like operations, y , on load tap-changers,
p g , etc.
●protections and control systems coordination ●protections and control systems coordination

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Static stability
y Static stabilityy

●Low amplitude phenomenon ●Low amplitude phenomenon

● Concerns small disturbances, for which electric parameters variations ● Concerns small disturbances, for which electric parameters variations
are slow and continuous. Linearization of network’s model equations is are slow and continuous. Linearization of network’s model equations is
then jjustified ((in p
particular,, the time variable does not occur)) then jjustified ((in p
particular,, the time variable does not occur))

●small disturbances (quasi-steady state) ●small disturbances (quasi-steady state)

●system linearization ●system linearization
●stability margins; spinning reserve ●stability margins; spinning reserve
p
●protections and control systems
y coordination p
●protections and control systems
y coordination

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Loss of angle
g static stability
y Loss of angle
g static stability
y

●Damping torque ●Damping torque

● Cd : torque coefficient that evolves in relation with speed disturbance ● Cd : torque coefficient that evolves in relation with speed disturbance
 
● Cd negative => aperiodical instability ● Cd negative => aperiodical instability

 

t t
disturbance duration disturbance duration
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Loss of angle
g static stability
y Loss of angle
g static stability
y

●Synchronizing torque ●Synchronizing torque

● Cs : torque coefficient that evolves in relation with internal angle ● Cs : torque coefficient that evolves in relation with internal angle
di
disturbance
b  di
disturbance
b 
● Cs negative => oscillating instability ● Cs negative => oscillating instability

 

t t
disturbance duration disturbance duration
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Conservation of angle
g static stability
y Conservation of angle
g static stability
y

● Damping and synchronizing torque coefficients are all positive ● Damping and synchronizing torque coefficients are all positive
● Internal angle  is subjected to a damped oscillation and reaches a final ● Internal angle  is subjected to a damped oscillation and reaches a final
value (generally different from initial value) that corresponds to a new value (generally different from initial value) that corresponds to a new
equilibrium equilibrium

 

t t
disturbance duration disturbance duration
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 Introduction: Issues and definitions Introduction: Issues and definitions
Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling
Parameters affecting
g transmitted p
power Parameters affecting
g transmitted p
power
Risky situations Risky situations
Black-Outs Black-Outs
Studies
S ud es to
o be ca
carried
ed ou
out Studies
S ud es to
o be ca
carried
ed ou
out
Application: case studies Application: case studies

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Mechanical modeling: Mechanical modeling:

active power / frequency coupling active power / frequency coupling

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Generator and rotating
g fields Generator and rotating
g fields

INDUCED INDUCED
(stator) (stator)
MAGNETIC MAGNETIC
FIELD FIELD

balanced 3-phase balanced 3-phase

VOLTAGE SYSTEM VOLTAGE SYSTEM
INDUCTOR INDUCTOR
(rotor) e = p.Ω (rotor) e = p.Ω
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Driving
g and resistant torques
q Driving
g and resistant torques
q

MECHANICAL ELECTRICAL MECHANICAL ELECTRICAL

TORQUE TORQUE TORQUE TORQUE
(dri ing torque)
(driving torq e) (braking torque) (dri ing torque)
(driving torq e) (braking torque)

delivered by the delivered by the

delivered by the delivered by the
turbine, linked to turbine, linked to
stator, linked to stator, linked to
mechanical power mechanical power
electrical power electrical power
produced
p produced
p
absorbed b by the absorbed b by the
loads (network) loads (network)

Shaft rotation Shaft rotation

speed Ω speed Ω

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Rotating
g masses equation
q Rotating
g masses equation
q

● Acceleration or deceleration of the rotating masses is linked to the ● Acceleration or deceleration of the rotating masses is linked to the
difference between electrical torque (braking torque) and mechanical difference between electrical torque (braking torque) and mechanical
masses inertia constant J
torque (driving torque) through the rotating masses’ masses inertia constant J
torque (driving torque) through the rotating masses’
(kg.m²) (kg.m²)

J · ∂Ω/∂t = m(t) - e(t) J · ∂Ω/∂t = m(t) - e(t)

● Solving this differential equation permits to determine the generator’s

generator s ● Solving this differential equation permits to determine the generator’s
generator s
behavior when a disturbance occurs, that is to answer to the behavior when a disturbance occurs, that is to answer to the
fundamental question: fundamental question:

Will the internal angle  stabilize into a normal and Will the internal angle  stabilize into a normal and
synchronous
h ti ?
operation? synchronous
h ti ?
operation?
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f / P coupling
p g f / P coupling
p g

● The fundamental rotating masses equation can be written as follows: ● The fundamental rotating masses equation can be written as follows:

J · (2/p)² · (f0 + f(t)) · ∂f/∂t = Pm(t) - Pe(t) J · (2/p)² · (f0 + f(t)) · ∂f/∂t = Pm(t) - Pe(t)

quasi-constant terms quasi-constant terms

frequency variation frequency variation

proportional to active power proportional to active power
unbalance unbalance

the proportionality relation is linked to the group the proportionality relation is linked to the group
‘turbine+generator’ construction (inertia, ...) ‘turbine+generator’ construction (inertia, ...)
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The link with internal angle
g The link with internal angle
g

Mechanical power delivered to the generator: Pm Mechanical power delivered to the generator: Pm

Electrical power delivered by the generator : Pe Electrical power delivered by the generator : Pe

• Pm = Pe : constant internal angle • Pm = Pe : constant internal angle

• Pm > Pe : increasing internal angle • Pm > Pe : increasing internal angle

• Pm < Pe : decreasing internal angle e • Pm < Pe : decreasing internal angle e

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Electrical modeling: Electrical modeling:

reactive power / voltage coupling reactive power / voltage coupling

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Equivalent
q diagram
g of a network Equivalent
q diagram
g of a network

generator
t t
transformer
f li
line i fi it network
infinite t k generator
t t
transformer
f li
line i fi it network
infinite t k

G G

equivalent star one-line diagram: equivalent star one-line diagram:

G S L R G S L R
I I
Xd Xt Rt Xl Rl Xd Xt Rt Xl Rl

E VS VL VR E VS VL VR

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Equivalent
q diagram
g of a network Equivalent
q diagram
g of a network

simplified equivalent diagram: simplified equivalent diagram:

G I R G I R

XT = Xd + Xt + Xl RT = Rt + Rl XT = Xd + Xt + Xl RT = Rt + Rl

E VR E VR

The mesh’ law is expressed as follows: E = VR + (RT + jXT) · I The mesh’ law is expressed as follows: E = VR + (RT + jXT) · I

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Kapp’s
pp diagram
g Kapp’s
pp diagram
g

E E
jXTI V jXTI V
 
 
VR RTI VR RTI
I I
V V

Neglecting RT beside XT, it results the following: Neglecting RT beside XT, it results the following:

V ≈ XTI*sin V ≈ XT*QR / VR V ≈ XTI*sin V ≈ XT*QR / VR

V ≈ XTI*cos V ≈ XT*PR / VR V ≈ XTI*cos V ≈ XT*PR / VR

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U / Q coupling
p g U / Q coupling
p g

● Transmission of definite active power P and reactive power Q between ● Transmission of definite active power P and reactive power Q between
two points of a network is accompanied by: two points of a network is accompanied by:
● an angular shift  between the voltages E and VR ● an angular shift  between the voltages E and VR
● a voltage drop: E - VR ≈ V ● a voltage drop: E - VR ≈ V

● The difference between E and VR voltages’ magnitudes (being close to ● The difference between E and VR voltages’ magnitudes (being close to
V) is mainly due reactive power transmission from G towards R V) is mainly due reactive power transmission from G towards R

g drop
To reduce the voltage p V,, one must g drop
To reduce the voltage p V,, one must
then avoid to carry reactive energy, and then avoid to carry reactive energy, and
therefore try to produce it at the nearest therefore try to produce it at the nearest
from
f consumption
ti places
l from
f consumption
ti places
l
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 Transmittable p
powers Transmittable p
powers

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pp
Apparent p
power transmitted pp
Apparent p
power transmitted

G I R G I R

jXTI jXTI
ZT = RT + jXT ZT = RT + jXT
 
E VR RTI E VR RTI

The apparent power transmitted to infinite network (node R) is: The apparent power transmitted to infinite network (node R) is:

S = VR · I* = (VR · E · e-j - VR²) · e-j/ZT S = VR · I* = (VR · E · e-j - VR²) · e-j/ZT

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Transmittable active power
p Transmittable active power
p

If the network resistance is neglected beside its reactance (RT << XT): If the network resistance is neglected beside its reactance (RT << XT):
● ZT = jXT ● ZT = jXT
●  = /2 ●  = /2

then the active power transmitted to the infinite network (node R) is: then the active power transmitted to the infinite network (node R) is:

P = Re(S) = (VR · E · sin) / XT P = Re(S) = (VR · E · sin) / XT

itt does therefore

t e e o e exist
e st a maximal
a a transmitted
t a s tted active
act e po
power o  = /
e for /2 itt does therefore
t e e o e exist
e st a maximal
a a transmitted
t a s tted active
act e po
power o  = /
e for /2
(static stability limit): (static stability limit):

Pmax = (VR · E) / XT Pmax = (VR · E) / XT

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Transmittable active p
power Transmittable active p
power
G S L R G S L R
I I
Xd Xt Rt Xl Rl Xd Xt Rt Xl Rl

E VS VL VR E VS VL VR

If instead of fix E (constant excitation), one fixes VS (voltage regulation), If instead of fix E (constant excitation), one fixes VS (voltage regulation),
then the maximal transmitted active power from S towards R becomes: then the maximal transmitted active power from S towards R becomes:

P’max = (VR · VS) / (Xt + Xl) > Pmax

P P’max = (VR · VS) / (Xt + Xl) > Pmax
P

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Transmittable active p
power Transmittable active p
power
G S L R G S L R
I I
Xd Xt Rt Xl Rl Xd Xt Rt Xl Rl

E VS VL VR E VS VL VR

As well, if one fixes VL ((voltage

g regulation
g at connection node),
) then the As well, if one fixes VL ((voltage
g regulation
g at connection node),
) then the
maximal transmitted active power from L towards R becomes: maximal transmitted active power from L towards R becomes:

P’’max = (VR · VL) / Xl > P’max > Pmax P’’max = (VR · VL) / Xl > P’max > Pmax

Voltage regulators action (excitation systems) allows then stable operation of the machine Voltage regulators action (excitation systems) allows then stable operation of the machine
in a zone where it is not « naturally » stable in a zone where it is not « naturally » stable
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Static stabilityy limit y limit

Static stability

static stability limit t ti masses equation

rotating ti with
ith static stability limit t ti masses equation
rotating ti with
ith
angles : angles :
Pm Pm
J·Ω·∂²/∂t² = Pm - PMax·sin J·Ω·∂²/∂t² = Pm - PMax·sin
stable unstable disturbance around the operating stable unstable disturbance around the operating
PMax PMax
point (Pm0 ; 0) : point (Pm0 ; 0) :
J·Ω·∂²/∂t² = - PMax·cos· J·Ω·∂²/∂t² = - PMax·cos·

Pm0 stable oscillation if Pm0 stable oscillation if

PMax·cos
cos>0 PMax·cos
cos>0
i.e.: i.e.:
0 <  < /2 0 <  < /2

Pe = PMax · sin Pe = PMax · sin

0 0 /2
/2 ’0   0 0 /2
/2 ’0  

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Areas equality
q y theorem Areas equality
q y theorem
b final situation: Pméca = Pm1 b final situation: Pméca = Pm1
a initial situation: Pméca = Pm0 a initial situation: Pméca = Pm0
-> new equilibrium point:  = 1 -> new equilibrium point:  = 1

Pm dynamic stability Pm dynamic stability

limit
acceleration phase: limit
acceleration phase:
A1 : kinetic energy stored by the A1 : kinetic energy stored by the
c machine during this phase c machine during this phase
PMax PMax
b A2 b’ b A2 b’
Pm1 Pm1
breaking phase: breaking phase:
A1 A1
A2 : kinetic energy restored by A2 : kinetic energy restored by
the machine during this phase the machine during this phase

Pm0 a energy conservation Pm0 a energy conservation

 A1 = A2  A1 = A2

Pe = PMax · sin Pe = PMax · sin

0 0 1 /2 m
/2 L   0 0 1 /2 m
/2 L  

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Behn-Eschenburg diagram in the Behn-Eschenburg diagram in the

P/Q map P/Q map

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Behn-Eschenburg
g Diagram
g Behn-Eschenburg
g Diagram
g
Operating
p gppoint Operating
p gppoint
S S
P I P I
Magnitude of E given Magnitude of E given
excitation Xd excitation Xd
 E ZR  E ZR
VS VS

Internal angle
of the machine
E Internal angle
of the machine
E
jXdI jXdI
 
 Q  Q
VS VS
I P = (E · VS · sin) / Xd I P = (E · VS · sin) / Xd
Q = (E · VS · cos - VS²)/ Xd Q = (E · VS · cos - VS²)/ Xd
Current fixed by Current fixed by
the load Voltage fixed by the network the load Voltage fixed by the network
(nominal voltage of the machine) (nominal voltage of the machine)
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p g limits: active p
Operating power p g limits: active p
Operating power

Generator (and prime Generator (and prime

P mover) mechanical P mover) mechanical
active power limit active power limit

E E

jXdI jXdI
 
 Q  Q
VS VS
I I
Motor operation Motor operation

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Operating
p g limits: apparent
pp power
p Operating
p g limits: apparent
pp power
p

Stator current limit Stator current limit

P (heating) P (heating)

E E
jXdI jXdI
 
 Q  Q
VS VS

I I
Schneider Electric - Energy Automation – Technical Institute 41 Schneider Electric - Energy Automation – Technical Institute 41

p g limits: excitation current

Operating p g limits: excitation current
Operating

P Excitation current P Excitation current

limit (rotor heating) limit (rotor heating)

Loss of Loss of
excitation limit excitation limit
E E

jXdI jXdI

 
 Q  Q
VS VS
I I

Schneider Electric - Energy Automation – Technical Institute 42 Schneider Electric - Energy Automation – Technical Institute 42
Operating
p g limits: internal angle
g Operating
p g limits: internal angle
g

Static stability P Static stability P

limit ( = /2) limit ( = /2)

E E
 jXdI  jXdI

I I
 
Q Q
VS VS

Schneider Electric - Energy Automation – Technical Institute 43 Schneider Electric - Energy Automation – Technical Institute 43

Operating
p g limits: conclusion Operating
p g limits: conclusion

S S
P P
I I

Xd Xd
 E ZR  E ZR
VS VS

E E
jXdI jXdI
 
 Q  Q
VS VS
I I

Schneider Electric - Energy Automation – Technical Institute 44 Schneider Electric - Energy Automation – Technical Institute 44
 Primary and secondary Primary and secondary
voltage / reactive power control voltage / reactive power control

Schneider Electric - Energy Automation – Technical Institute 45 Schneider Electric - Energy Automation – Technical Institute 45

Voltage:
g a fluctuating
g value Voltage:
g a fluctuating
g value

slow variations fast variations slow variations fast variations

consumption cycles events consumption cycles events

● season cycle ● changes of topology ● season cycle ● changes of topology

● weekly
kl cycle
l ● generators tripping
i i ● weekly
kl cycle
l ● generators tripping
i i
● daily cycle ● loads fluctuations ● daily cycle ● loads fluctuations
● weather ● weather
● ... ● ...

Need for a ‘continuous’ watch of the voltage on transmission and Need for a ‘continuous’ watch of the voltage on transmission and
distribution grids distribution grids
Schneider Electric - Energy Automation – Technical Institute 46 Schneider Electric - Energy Automation – Technical Institute 46
 Voltage
g control and static stability
y Voltage
g control and static stability
y
PR, QR PR, QR
Assumptions: Assumptions:
I I
● E = constant as PR changes (constant excitation) ● E = constant as PR changes (constant excitation)
X ● QR = 0 (reactive power compensation at X ● QR = 0 (reactive power compensation at
 E ZR transformation stations))  E ZR transformation stations))
VR VR
● VR not regulated ● VR not regulated

It results VR = E · cos, i.e.: (PR = VR² · sin2) / 2X It results VR = E · cos, i.e.: (PR = VR² · sin2) / 2X
The maximal transmittable power per phase is therefore PMax = VR² / 2X The maximal transmittable power per phase is therefore PMax = VR² / 2X

If VR is maintained equal to E by reactive compensation (QR ≠ 0), then: If VR is maintained equal to E by reactive compensation (QR ≠ 0), then:
P
P’Max = E · VR /X ≈ E²
E / X > PMax P
P’Max = E · VR /X ≈ E
E² / X > PMax

Voltage control on several nodes of the network permits to improve its Voltage control on several nodes of the network permits to improve its
static stability static stability
Schneider Electric - Energy Automation – Technical Institute 47 Schneider Electric - Energy Automation – Technical Institute 47

Voltage
g control and static stability
y Voltage
g control and static stability
y

critical point critical point

VR / E VR / E
PR = ((E · VR · sin)) / X PR = ((E · VR · sin)) / X
1 1
QR = (E · VR · cos - VS²)/ X QR = (E · VR · cos - VS²)/ X

E² E4 E² cos  = 1 E² E4 E² cos  = 1
VR ²   QR  X  X   PR ²  QR  VR ²   QR  X  X   PR ²  QR 
2 4 X² X cos  = 0.95 2 4 X² X cos  = 0.95
cos  = 0.9 cos  = 0.9
Q = -0.2 p.u. Q = -0.2 p.u.
(compensation) (compensation)

1 PR / PMax 1 PR / PMax


VR ²  X  PMax  QR  PMax ²  PR ²  2PMax  QR  
VR ²  X  PMax  QR  PMax ²  PR ²  2PMax  QR 
Schneider Electric - Energy Automation – Technical Institute 48 Schneider Electric - Energy Automation – Technical Institute 48
Primary
y control Primaryy control

Local, fast, and continuous stator voltage control Local, fast, and continuous stator voltage control

measure measure

Vs Vs
Vref + Vs Vref + Vs
-
AVR G -
AVR G

● For each generator ● For each generator

● Constant voltage at generators’
generators terminals ● Constant voltage at generators’
generators terminals
● Response time: few hundreds of milliseconds ● Response time: few hundreds of milliseconds

Schneider Electric - Energy Automation – Technical Institute 49 Schneider Electric - Energy Automation – Technical Institute 49

Secondary
y control Secondaryy control

Regional and continuous network voltage control Regional and continuous network voltage control

measure measure

Vs Vs
Vref + Vs Vref + Vs
-
AVR G -
AVR G
+ Q + Q
V V
Vp Vp
Q control Q control
Qlim Qlim
N - N -
PI PI
+ +
other controlling
gggroups
p Vpref other controlling
gggroups
p Vpref

● At ‘zonal’ level ● At ‘zonal’ level

national national
● Constant voltageg at p
pilot bus dispatching ● Constant voltageg at p
pilot bus dispatching
● Response time: few seconds ● Response time: few seconds
Schneider Electric - Energy Automation – Technical Institute 50 Schneider Electric - Energy Automation – Technical Institute 50
 Primary and secondary Primary and secondary
frequency / active power control frequency / active power control

Schneider Electric - Energy Automation – Technical Institute 51 Schneider Electric - Energy Automation – Technical Institute 51

Frequency: reflect of production / Frequency: reflect of production /

cons mption balance
consumption cons mption balance
consumption

●In the case of balance rupture between production and ●In the case of balance rupture between production and
consumption, frequency is the first parameter that reflects consumption, frequency is the first parameter that reflects
the evolution the evolution

●The risks if frequency is not controlled: ●The risks if frequency is not controlled:
● Loss of synchronism ● Loss of synchronism
● Electrical and mechanical constraints applied on equipments sensitive to ● Electrical and mechanical constraints applied on equipments sensitive to
frequency (turbine blades, windings, etc.) frequency (turbine blades, windings, etc.)
● Generator stall, leading to Blackout in extreme cases ● Generator stall, leading to Blackout in extreme cases
oss o
● Loss of e
exploitation
p o a o du during
g reconstruction
eco s uc o p phase
ase oss o
● Loss of e
exploitation
p o a o du during
g reconstruction
eco s uc o p phase
ase

Schneider Electric - Energy Automation – Technical Institute 52 Schneider Electric - Energy Automation – Technical Institute 52
Droop
p Droop
p

The droop defines the relation between active power and frequency of a The droop defines the relation between active power and frequency of a
machine or a production plant machine or a production plant

f ● In % of nominal frequency f ● In % of nominal frequency

fmax ● R = 100 · (fmax-ffmin) / f0 fmax ● R = 100 · (fmax-ffmin) / f0
● The machine power variation ● The machine power variation
f1 f1
is proportional to speed is proportional to speed
f0 f0
f1 variation f1 variation

fmin fmin

P P
P1 P0 P1 Pn P1 P0 P1 Pn

Schneider Electric - Energy Automation – Technical Institute 53 Schneider Electric - Energy Automation – Technical Institute 53

Composite frequency response Composite frequency response

characteristic characteristic

The energy that is necessary to maintain frequency is proportional to The energy that is necessary to maintain frequency is proportional to
produced power, the proportionality coefficient is called inertia constant produced power, the proportionality coefficient is called inertia constant
(H in MW
(H, MW.s-1
s-1 / MVA) (H in MW
(H, MW.s-1
s-1 / MVA)
f f

fmax fmax
● This energy is called ● This energy is called
f1 f1
composite frequency response composite frequency response
f0 f0
f1
characteristic f1
characteristic
●  = Pn / (R · f0), in MW / Hz ●  = Pn / (R · f0), in MW / Hz
fmin ● The frequency variation rate fmin ● The frequency variation rate
depends on the electrical depends on the electrical
system inertia constant system inertia constant

P P
P1 P0 P1 Pn P1 P0 P1 Pn

Schneider Electric - Energy Automation – Technical Institute 54 Schneider Electric - Energy Automation – Technical Institute 54
Primary
y control Primaryy control

Local, fast, and continuous active power control Local, fast, and continuous active power control

1/R 1/R
P f P f
Pref + Pref +

-
Regul. T G -
Regul. T G

● For each generator ● For each generator

● Maintain of production / consumption balance ● Maintain of production / consumption balance
● Response time: few seconds to 10 s ● Response time: few seconds to 10 s

Schneider Electric - Energy Automation – Technical Institute 55 Schneider Electric - Energy Automation – Technical Institute 55

Secondary
y control Secondaryy control

Regional and continuous frequency control Regional and continuous frequency control
interconnection line interconnection line
1/R 1/R
P P
Pref + f Pref + f
-
Regul. T G -
Regul. T G
+ +
P PI P PI

Ps f Ps f
X secondary reserve
f0 X secondary reserve
f0
PIref PIref
N + N +
- -
PI + PI +
- -
 
other controlling groups other controlling groups
= secondary composite = secondary composite
frequency response frequency response
● At national level characteristic (MW/Hz) ● At national level characteristic (MW/Hz)

● Constant frequency and maintain of power exchanges on interconnection ● Constant frequency and maintain of power exchanges on interconnection
li
lines att th
their
i contractual
t t l values
l li
lines att th
their
i contractual
t t l values
l
● Response time: few minutes ● Response time: few minutes
Schneider Electric - Energy Automation – Technical Institute 56 Schneider Electric - Energy Automation – Technical Institute 56
Conclusion on f / P control Conclusion on f / P control

● Primary control realizes production / consumption balance and ● Primary control realizes production / consumption balance and
stabilizes the network stabilizes the network
● Leads to a slow frequency and inter-regional
inter regional power exchange drift ● Leads to a slow frequency and inter-regional
inter regional power exchange drift
(interconnections) (interconnections)
f f

f1 f1
● fast action of primary control ● fast action of primary control
f0 f0

● slower action of secondary control ● slower action of secondary control

P P
P1 P0 Pn P1 P0 Pn

● Secondary control regulates frequency and inter-regional exchanges ● Secondary control regulates frequency and inter-regional exchanges
● Re-dispatching of primary control set points ● Re-dispatching of primary control set points
Schneider Electric - Energy Automation – Technical Institute 57 Schneider Electric - Energy Automation – Technical Institute 57

Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder

R
Regulators
l t modeling
d li R
Regulators
l t modeling
d li
Parameters affecting
g transmitted p
power Parameters affecting
g transmitted p
power
Risky situations Risky situations
Black-Outs Black-Outs
Studies
S ud es to
o be ca
carried
ed ou
out Studies
S ud es to
o be ca
carried
ed ou
out
Application: case studies Application: case studies

Schneider Electric - Energy Automation – Technical Institute 58 Schneider Electric - Energy Automation – Technical Institute 58
Objectives
j of modeling
g Objectives
j of modeling
g

● A model is a mathematic image (state matrix, differential equations, ● A model is a mathematic image (state matrix, differential equations,
etc.) of a given system that aims to represent in a more or less detailed etc.) of a given system that aims to represent in a more or less detailed
way the real physical behavior of the system way the real physical behavior of the system

● The goal of a mathematical modeling of a physical system is to ● The goal of a mathematical modeling of a physical system is to
determine the system behavior (machine, or more generally electric determine the system behavior (machine, or more generally electric
system) facing a given disturbance system) facing a given disturbance

● Electrical network dynamic simulation software are available, such as: ● Electrical network dynamic simulation software are available, such as:
● PSAF/STAB CYME (Canada) ● PSAF/STAB CYME (Canada)
● EUROSTAG RTE (France) / TRACTEBEL (Beglium) ● EUROSTAG RTE (France) / TRACTEBEL (Beglium)

Schneider Electric - Energy Automation – Technical Institute 59 Schneider Electric - Energy Automation – Technical Institute 59

From p
physics
y to mathematic model From p
physics
y to mathematic model

mechanical / thermodynamic equations mechanical / thermodynamic equations

electromagnetic equations electromagnetic equations

control command laws

control-command control command laws
control-command
Schneider Electric - Energy Automation – Technical Institute 60 Schneider Electric - Energy Automation – Technical Institute 60
From p y
physics to mathematic model From p y
physics to mathematic model

voltage
g regulation
g voltage
g regulation
g
control command controlled control command controlled
measured set point measured set point
signal signal value signal signal value
values values
Vref Vref

+ +
Vs Vc  Vr Efd Vs Vc  Vr Efd
Is transducer -
AVR + exciter generator Vs Is transducer -
AVR + exciter generator Vs
- - - -

saturation saturation

stabilization stabilization
Schneider Electric - Energy Automation – Technical Institute 61 Schneider Electric - Energy Automation – Technical Institute 61

From p
physics
y to mathematic model From p
physics
y to mathematic model

speed
p /p g
power regulation speed
p /p g
power regulation
set point command controlled set point command controlled
measured measured
control g
signal value control g
signal value
value value
signal signal
Ωref Ωref

+
  admission
d i i +
  admission
d i i
m m
Ω
-
servo-pilot prime mover generator Pe Ω
-
servo-pilot prime mover generator Pe
- transmission - transmission

stabilization stabilization

Schneider Electric - Energy Automation – Technical Institute 62 Schneider Electric - Energy Automation – Technical Institute 62
Voltage
g regulation:
g yp
typical model Voltage
g regulation:
g yp
typical model
Ω0 Ω0
Power System Stabilizer Power System Stabilizer
VSmax VSmax
1+T1s Tss + 1+T1s Tss +
Ks Ω Ks Ω
1+T2s 1+Tss - 1+T2s 1+Tss -
VSmin VSmin

Vref Vref
transducer transducer
g Regulator
Automatic Voltage g exciter g Regulator
Automatic Voltage g exciter
Vs VRmax Vs VRmax
Is Rc+jXc Is Rc+jXc
+ + + + + +
Vc +  1+TCs KA Vr 1 Vc +  1+TCs KA Vr 1
Vs Efd Vs Efd
+ - - 1+TBs 1+TAs + - TEs + - - 1+TBs 1+TAs + - TEs
Vf VUEL VRmin Vf VUEL VRmin

+ +
Ke Ke
+ +
X Ae·eBex X Ae·eBex

stabilization stabilization
saturation saturation

KFs KFs
1+TFs 1+TFs
Schneider Electric - Energy Automation – Technical Institute 63 Schneider Electric - Energy Automation – Technical Institute 63

p
Speed g
regulation: hydraulic
y p
Speed g
regulation: hydraulic
y

servo-pilot servo-pilot
Ω0 Ω0
Tmax-Ouv 1 Tmax-Ouv 1
gate turbine gate turbine

+ +
 KS 1  1 F 1-TWs  KS 1  1 F 1-TWs
Ω - m Ω - m
- 1+TPs s 1+TGs 1+0.5·TWs - 1+TPs s 1+TGs 1+0.5·TWs
Tmax-Ferm 0 Tmax-Ferm 0

stabilization loop stabilization loop

+ +
RP RP
+ +
TRs TRs
RT RT
1+TRs 1+TRs

Schneider Electric - Energy Automation – Technical Institute 64 Schneider Electric - Energy Automation – Technical Institute 64
 Speed
p g
regulation: thermal Speed
p g
regulation: thermal

servo-pilot Ω0 servo-pilot Ω0
1 1
Tmax-Ouv Kpr Tmax-Ouv Kpr
1 + + 1 + +
KSM
+  +
Kg Ω KSM
+  +
Kg Ω
s - - - s - - -
1 - 1 -
Tmax-Ferm Tmax-Ferm
0 Tis 0 Tis

turbine turbine

+ + + +
+ + + +
   
admission K K admission K K

1 1 + 1 1 +
Pref Pt Fhp 1 + Pref Pt Fhp 1 +
X boiler X m X boiler X m
+ - 1+Tchs 1+Ts 1+Ts + + - 1+Tchs 1+Ts 1+Ts +

Kpd x² K K Kpd x² K K

+ + + +

+ + + +

Schneider Electric - Energy Automation – Technical Institute 65 Schneider Electric - Energy Automation – Technical Institute 65

Transfer function Transfer function

Automatic Voltage Regulator Automatic Voltage Regulator
VRmax VRmax

 1+TCs x KA Vr  1+TCs x KA Vr
1+TBs 1+TAs 1+TBs 1+TAs
VUEL VRmin VUEL VRmin

1 TCs
1+T dx 1 T dε 1 1 TCs
1+T dx 1 T dε 1
l d l fil
lead-lag filter:  x C   ε llead-lag
d l fil
filter:  x C   ε
1+TBs dt TB TB dt TC 1+TBs dt TB TB dt TC

KA dVr 1 K KA dVr 1 K
simple-lag filter:  Vr  A x simple-lag filter:  Vr  A x
1+TAs dt TA TA 1+TAs dt TA TA

d² Vr TA  TB dVr 1 K  T dε 1  d² Vr TA  TB dVr 1 K  T dε 1 
   Vr  A  C   ε    Vr  A  C   ε
dt ² TA  TB dt TA  TB TA T
 B dt TC  dt ² TA  TB dt TA  TB TA T
 B dt TC 

Schneider Electric - Energy Automation – Technical Institute 66 Schneider Electric - Energy Automation – Technical Institute 66
Transfer function Transfer function
Automatic Voltage Regulator Automatic Voltage Regulator
VRmax VRmax

 1+TCs x KA Vr d² Vr TA  TB dVr 1 K  T dε 1   1+TCs x KA Vr d² Vr TA  TB dVr 1 K  T dε 1 

   Vr  A  C   ε    Vr  A  C   ε
1+TBs 1+TAs dt ² TA  TB dt TA  TB TA  TB dt TC  1+TBs 1+TAs dt ² TA  TB dt TA  TB TA  TB dt TC 
VUEL VRmin VUEL VRmin

Vr(s) 1  Tc s Vr(s) 1  Tc s
Laplace transformation:  H(s)  K A Laplace transformation:  H(s)  K A
ε(s) (1  TB s)  (1  TA s) ε(s) (1  TB s)  (1  TA s)

The transfer function poles (spi so as the denominator is equal to zero) provide The transfer function poles (spi so as the denominator is equal to zero) provide
indication about the system stability (Eigen modes): indication about the system stability (Eigen modes):
●real part: damping (negative real part  stable mode) ●real part: damping (negative real part  stable mode)
●imaginary part: frequency of oscillation ●imaginary part: frequency of oscillation

The transfer function zeros (s0i so as the numerator is equal to zero) provide The transfer function zeros (s0i so as the numerator is equal to zero) provide
indication about the system robustness (overreach, etc.) indication about the system robustness (overreach, etc.)
Schneider Electric - Energy Automation – Technical Institute 67 Schneider Electric - Energy Automation – Technical Institute 67

Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling

Parameters affecting
g transmitted p
power Parameters affecting
g transmitted p
power
Risky situations Risky situations
Black-Outs Black-Outs
S ud es to
Studies o be ca ed ou
carried out S ud es to
Studies o be ca ed ou
carried out
Application: case studies Application: case studies

Schneider Electric - Energy Automation – Technical Institute 68 Schneider Electric - Energy Automation – Technical Institute 68
Machine p g
parameters: internal angle Machine p g
parameters: internal angle

Pm Pm

Pe Pe

PMax PMax
Pm Pm

PMax PMax

Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 69 Schneider Electric - Energy Automation – Technical Institute 69

Machine parameters:
p internal angle
g Machine p
parameters: internal angle
g

Pm Pm

Pe Pe

PMax PMax
Pm Pm

PMax PMax
Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 70 Schneider Electric - Energy Automation – Technical Institute 70
Machine p g
parameters: internal angle Machine p g
parameters: internal angle

Pm Pm

Pe Pe

PMax PMax
Pm Pm

PMax PMax

Pe Pe

e e
0 /2
/    0 /2
/   

Schneider Electric - Energy Automation – Technical Institute 71 Schneider Electric - Energy Automation – Technical Institute 71

Machine parameters:
p excitation Machine parameters:
p excitation

Pm Pm
E E
Pe Pe
Nominal excitation Nominal excitation

PMax PMax
Pm Pm

PMax PMax

Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 72 Schneider Electric - Energy Automation – Technical Institute 72
Machine p
parameters: excitation Machine p
parameters: excitation

Pm Pm
E E
Pe Pe
Over-Excitation Over-Excitation

PMax PMax
Pm Pm
PMax PMax

Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 73 Schneider Electric - Energy Automation – Technical Institute 73

Machine p
parameters: excitation p
Machine parameters: excitation

Pm Pm
E E
Pe Pe
Under-Excitation Under-Excitation

PMax PMax
Pm Pm

PMax PMax
Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 74 Schneider Electric - Energy Automation – Technical Institute 74
Network parameters: Network parameters:
network
impedance of the link to infinite net ork network
impedance of the link to infinite net ork

Pm Pm
G G
Pe Pe
dense meshed grid dense meshed grid
PMax PMax
Pm Pm
PMax PMax

Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 75 Schneider Electric - Energy Automation – Technical Institute 75

Network parameters: Network parameters:

network
impedance of the link to infinite net ork network
impedance of the link to infinite net ork

Pm Pm
G G
Pe Pe
light meshed grid light meshed grid
PMax PMax
Pm Pm

PMax PMax

Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 76 Schneider Electric - Energy Automation – Technical Institute 76
Network p g
parameters: network voltage Network p g
parameters: network voltage

Pm Pm
VR VR
Pe Pe
The influence of the network voltage on The influence of the network voltage on
the transmittable active power is analogue the transmittable active power is analogue
PMax PMax
the influence of excitation voltage the influence of excitation voltage
Pm Pm

PMax PMax

Pe Pe

e e
0  /2
/   0  /2
/  

Schneider Electric - Energy Automation – Technical Institute 77 Schneider Electric - Energy Automation – Technical Institute 77

Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling
Parameters affecting transmitted power Parameters affecting transmitted power

Risky situations Risky situations

Black-Outs Black-Outs
S ud es to
Studies carried
o be ca ed ou
out S ud es to
Studies carried
o be ca ed ou
out
Application: case studies Application: case studies

Schneider Electric - Energy Automation – Technical Institute 78 Schneider Electric - Energy Automation – Technical Institute 78
 Line opening
p g Line opening
p g

Schneider Electric - Energy Automation – Technical Institute 79 Schneider Electric - Energy Automation – Technical Institute 79

p 1: stability
Example y is conserved p 1: stability
Example y is conserved

Pm Pm
G G
Pe Pe
initial state initial state
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 80 Schneider Electric - Energy Automation – Technical Institute 80
Example
p 1: stability
y is conserved Example
p 1: stability
y is conserved

Pm Pm
G G
Pe Pe
line opening line opening
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 81 Schneider Electric - Energy Automation – Technical Institute 81

p 1: stability
Example y is conserved p 1: stability
Example y is conserved

Pm Pm
G G
Pe Pe
acceleration phase acceleration phase
PMax PMax
Pm Pm

PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 82 Schneider Electric - Energy Automation – Technical Institute 82
Example
p 1: stability
y is conserved Example
p 1: stability
y is conserved

Pm Pm
G G
Pe Pe
braking phase braking phase
PMax PMax
Pm Pm

PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 83 Schneider Electric - Energy Automation – Technical Institute 83

p 1: stability
Example y is conserved p 1: stability
Example y is conserved

Pm Pm
G G
Pe Pe
stabilization stabilization
PMax PMax
Pm Pm

PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 84 Schneider Electric - Energy Automation – Technical Institute 84
Example
p 2: stability
y is lost Example
p 2: stability
y is lost

Pm Pm
G G
Pe Pe
initial state initial state
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 85 Schneider Electric - Energy Automation – Technical Institute 85

p 2: stability
Example y is lost p 2: stability
Example y is lost

Pm Pm
G G
Pe Pe
line opening line opening
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 86 Schneider Electric - Energy Automation – Technical Institute 86
Example
p 2: stability
y is lost Example
p 2: stability
y is lost

Pm Pm
G G
Pe Pe
acceleration phase acceleration phase
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 87 Schneider Electric - Energy Automation – Technical Institute 87

p 2: stability
Example y is lost p 2: stability
Example y is lost

Pm Pm
G G
Pe Pe
stalling stalling
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 88 Schneider Electric - Energy Automation – Technical Institute 88
 Global voltage
g drop
p Global voltage
g drop
p

Schneider Electric - Energy Automation – Technical Institute 89 Schneider Electric - Energy Automation – Technical Institute 89

g drop
Voltage p g drop
Voltage p

Pm Pm
VR VR
Pe Pe
initial state initial state

PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 90 Schneider Electric - Energy Automation – Technical Institute 90
Voltage
g drop
p Voltage
g drop
p

Pm Pm
VR VR
Pe Pe
network voltage drop network voltage drop

PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 91 Schneider Electric - Energy Automation – Technical Institute 91

Voltage
g drop
p Voltage
g drop
p

Pm Pm
VR VR
Pe Pe
acceleration phase acceleration phase

PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 92 Schneider Electric - Energy Automation – Technical Institute 92
Voltage
g drop
p Voltage
g drop
p

Pm Pm
VR VR
Pe Pe
voltage is back voltage is back

PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 93 Schneider Electric - Energy Automation – Technical Institute 93

Voltage
g drop
p Voltage
g drop
p

Pm Pm
VR VR
Pe Pe
braking phase braking phase

PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 94 Schneider Electric - Energy Automation – Technical Institute 94
 p of U
Influence of the depth p of U
Influence of the depth

VR VR VR VR

Pm Vn Pm Vn Pm Vn Pm Vn
PMax PMax PMax PMax

Pm Pm Pm Pm

0 /2   0 /2   0 /2   0 /2  

A2 > A1 : stable A2 < A1 : unstable A2 > A1 : stable A2 < A1 : unstable

Schneider Electric - Energy Automation – Technical Institute 95 Schneider Electric - Energy Automation – Technical Institute 95

Influence of the duration of U Influence of the duration of U

VR VR VR VR

Pm Vn Pm Vn Pm Vn Pm Vn
PMax PMax PMax PMax

Pm Pm Pm Pm

0 /2   0 /2   0 /2   0 /2  

A2 > A1 : stable A2 < A1 : unstable A2 > A1 : stable A2 < A1 : unstable

Schneider Electric - Energy Automation – Technical Institute 96 Schneider Electric - Energy Automation – Technical Institute 96
 Short-circuit on the network Short-circuit on the network

Schneider Electric - Energy Automation – Technical Institute 97 Schneider Electric - Energy Automation – Technical Institute 97

Short-circuit Short-circuit

Pm Pm
G G
Pe Pe
initial state initial state
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 98 Schneider Electric - Energy Automation – Technical Institute 98
Short-circuit Short-circuit

Pm Pm
G G
Pe Pe
occurrence of a short-circuit occurrence of a short-circuit
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 99 Schneider Electric - Energy Automation – Technical Institute 99

Short-circuit Short-circuit

Pm Pm
G G
Pe Pe
acceleration phase acceleration phase
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 100 Schneider Electric - Energy Automation – Technical Institute 100
Short-circuit Short-circuit

Pm Pm
G G
Pe Pe
line tripping line tripping
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 101 Schneider Electric - Energy Automation – Technical Institute 101

Short-circuit Short-circuit

Pm Pm
G G
Pe Pe
braking phase braking phase
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 102 Schneider Electric - Energy Automation – Technical Institute 102
Influence of the type
yp of short-circuit Influence of the type
yp of short-circuit

Pm Pm
no short-circuit no short-circuit

one-phase-to-ground short-circuit one-phase-to-ground short-circuit

two-phase short-circuit two-phase short-circuit

two-phase-to-ground short-circuit two-phase-to-ground short-circuit

three-phase short-circuit three-phase short-circuit

0 /2
/2   0 /2
/2  

Schneider Electric - Energy Automation – Technical Institute 103 Schneider Electric - Energy Automation – Technical Institute 103

Influence of network mesh densityy Influence of network mesh density

y

G G G G

Pm Pm Pm Pm
PMax
M PMax
M PMax
M PMax
M

Pm Pm Pm Pm

0 /2   0 /2   0 /2   0 /2  

A2 > A1 : stable A2 < A1 : unstable A2 > A1 : stable A2 < A1 : unstable

Schneider Electric - Energy Automation – Technical Institute 104 Schneider Electric - Energy Automation – Technical Institute 104
Influence of fault clearing
g time Influence of fault clearing
g time

G G G G

t t t t
Pm Pm Pm Pm
PMax PMax PMax PMax

Pm Pm Pm Pm

0 /2   0 /2
/   0 /2   0 /2
/  

A2 > A1 : stable A2 < A1 : unstable A2 > A1 : stable A2 < A1 : unstable

Schneider Electric - Energy Automation – Technical Institute 105 Schneider Electric - Energy Automation – Technical Institute 105

Automatic reclose system

y Automatic reclose system
y

Schneider Electric - Energy Automation – Technical Institute 106 Schneider Electric - Energy Automation – Technical Institute 106
Automatic recloser Automatic recloser

Pm Pm
G G
Pe Pe
initial state initial state
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 107 Schneider Electric - Energy Automation – Technical Institute 107

Automatic recloser Automatic recloser

Pm Pm
G G
Pe Pe
short-circuit short-circuit
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 108 Schneider Electric - Energy Automation – Technical Institute 108
Automatic recloser Automatic recloser

Pm Pm
G G
Pe Pe
trip trip
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 109 Schneider Electric - Energy Automation – Technical Institute 109

Automatic recloser Automatic recloser

Pm Pm
G G
Pe Pe
reclosing reclosing
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 110 Schneider Electric - Energy Automation – Technical Institute 110
Synchro-check
y Synchro-check
y

● The generator and the network are synchronous together ● The generator and the network are synchronous together

G G

Schneider Electric - Energy Automation – Technical Institute 111 Schneider Electric - Energy Automation – Technical Institute 111

Synchro-check
y Synchro-check
y

● Short-circuit: the link between the generator and the network is very ● Short-circuit: the link between the generator and the network is very
weak weak

G G

Schneider Electric - Energy Automation – Technical Institute 112 Schneider Electric - Energy Automation – Technical Institute 112
Synchro-check
y Synchro-check
y

● Line opening: the generator evolves independently from the network ● Line opening: the generator evolves independently from the network

G G

Schneider Electric - Energy Automation – Technical Institute 113 Schneider Electric - Energy Automation – Technical Institute 113

Synchro-check
y Synchro-check
y

● Reclosing: it is essential to check the synchronism between generator ● Reclosing: it is essential to check the synchronism between generator
and network voltage before allowing line reclosing and network voltage before allowing line reclosing

G G

│V│ ≤ Vmax │V│ ≤ Vmax

││ ≤ max ││ ≤ max
LB: live
LB li b bus LB: live
LB li b bus LB: live
LB li b bus LB: live
LB li b bus
DB: dead bus │f│ ≤ fmax DB: dead bus DB: dead bus │f│ ≤ fmax DB: dead bus
LL: live line LL: live line LL: live line LL: live line
DL: dead line DL: dead line DL: dead line DL: dead line

Schneider Electric - Energy Automation – Technical Institute 114 Schneider Electric - Energy Automation – Technical Institute 114
Synchro-check
y Synchro-check
y

G G

LB-DL: wait LB-DL: reclose LB-DL: wait LB-DL: reclose

Schneider Electric - Energy Automation – Technical Institute 115 Schneider Electric - Energy Automation – Technical Institute 115

Synchro-check
y Synchro-check
y

G G

LB-LL: synchro-check LB-LL: synchro-check

synchronism conditions not OK: wait synchronism conditions not OK: wait

Schneider Electric - Energy Automation – Technical Institute 116 Schneider Electric - Energy Automation – Technical Institute 116
Synchro-check
y Synchro-check
y

G G

LB-LL: synchro-check LB-LL: synchro-check

synchronism conditions OK: reclose synchronism conditions OK: reclose

Schneider Electric - Energy Automation – Technical Institute 117 Schneider Electric - Energy Automation – Technical Institute 117

Production / consumption Production / consumption

balance rupture balance rupture

Schneider Electric - Energy Automation – Technical Institute 118 Schneider Electric - Energy Automation – Technical Institute 118
Heavy
y load switched on Heavy
y load switched on

Pm Pm
G G
Pe Pe
initial state initial state
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 119 Schneider Electric - Energy Automation – Technical Institute 119

Heavyy load switched on Heavy

y load switched on

Pm Pm
G G
Pe Pe
load switch-on load switch-on
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 120 Schneider Electric - Energy Automation – Technical Institute 120
Heavy
y load switched on Heavy
y load switched on

Pm Pm
G G
Pe Pe
primary control (droop) primary control (droop)
PMax PMax
Pm Pm
PMax PMax

Pm Pm

e e
0 /2
/   0 /2
/  

Schneider Electric - Energy Automation – Technical Institute 121 Schneider Electric - Energy Automation – Technical Institute 121

Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling
Parameters affecting transmitted power Parameters affecting transmitted power
Risky situations Risky situations

Bl k O t
Black-Outs Bl k O t
Black-Outs
S ud es to
Studies o be ca ed ou
carried out S ud es to
Studies o be ca ed ou
carried out
Application: case studies Application: case studies

Schneider Electric - Energy Automation – Technical Institute 122 Schneider Electric - Energy Automation – Technical Institute 122
 What is a black-out ? What is a black-out ?

Major incident Recurrent phenomenon Major incident Recurrent phenomenon

● wide territories ● New York 1965 ● wide territories ● New York 1965
● high depth (number of un- ● New York 1978 ● high depth (number of un- ● New York 1978
supplied customers) ● France 1978 supplied customers) ● France 1978
● long time break (several hours) ● Sweden 1983 ● long time break (several hours) ● Sweden 1983
● conjunction of an initiating ● France 1987 ● conjunction of an initiating ● France 1987
eventt and
d aggravating
ti ffactors
t eventt and
d aggravating
ti ffactors
t
● USA 1996 ● USA 1996
● severe damages ● severe damages
● USA / Canada 2003 ● USA / Canada 2003
● Denmark / Sweden 2003 ● Denmark / Sweden 2003
● Italy 2003 ● Italy 2003
● Germany 2006 ● Germany 2006

Schneider Electric - Energy Automation – Technical Institute 123 Schneider Electric - Energy Automation – Technical Institute 123

Major
j incident formation mechanism Major
j incident formation mechanism

● Chronology of a major incident ● Chronology of a major incident

initiating
g critical Black initiating
g critical Black
event event Out event event Out

normal pre- quasi-steady state normal normal pre- quasi-steady state normal
series reconstruction series reconstruction
situation
s tuat o incident
c de t evolution
e o ut o situation ssituation
tuat o incident
c de t evolution
e o ut o situation

sequence of series events sequence of series events

system in stressed conditions system in stressed conditions

Schneider Electric - Energy Automation – Technical Institute 124 Schneider Electric - Energy Automation – Technical Institute 124
Major
j incident formation mechanism Major
j incident formation mechanism

● Pre-conditions ● Pre-conditions
● Stressed system: summer or winter consumption peaks, N-1 criterion ● Stressed system: summer or winter consumption peaks, N-1 criterion
● Inappropriate reactive power spinning reserve ● Inappropriate reactive power spinning reserve
● Some major equipments out of service ● Some major equipments out of service
● Aging equipments ● Aging equipments
● Natural causes: wind, storms, geomagnetic disturbances, fires, etc. ● Natural causes: wind, storms, geomagnetic disturbances, fires, etc.

● Initiating events and aggravating factors ● Initiating events and aggravating factors
● Natural causes: storm, geomagnetic storm, earthquake, lightning strike, ● Natural causes: storm, geomagnetic storm, earthquake, lightning strike,
contact with a tree,… contact with a tree,…
● Technical
T h i l causes: short-circuits,
h t i it componentt failures,
f il heavy
h lload,
d major
j ● Technical
T h i l causes: short-circuits,
h t i it componentt failures,
f il heavy
h lload,
d major
j
component maintenance,… component maintenance,…
● Human causes: maneuver errors, wrong or inappropriate communications ● Human causes: maneuver errors, wrong or inappropriate communications
between operators, lack of training,… between operators, lack of training,…

Schneider Electric - Energy Automation – Technical Institute 125 Schneider Electric - Energy Automation – Technical Institute 125

Example : Italy 2003 Example : Italy 2003

origin of the incident origin of the incident
SWITZERLAND AUSTRIA SWITZERLAND AUSTRIA

SLOVENIA SLOVENIA

Initiating event at Initiating event at

2212 MW 2212 MW
03h01’42’’: 03h01’42’’:
FRANCE
• 380 kV Lavorgo-Mettlen
g line FRANCE
• 380 kV Lavorgo-Mettlen
g line
tripping after arcing (tree) – tripping after arcing (tree) –
heavily loaded line (86% of Ith) heavily loaded line (86% of Ith)
• Auto-reclose failure due to high • Auto-reclose failure due to high
angular difference ( = 4242°)) angular difference ( = 4242°))

Pre-conditions at 03h00: Pre-conditions at 03h00:

• Total consumption inside Italy: 27 444 MW • Total consumption inside Italy: 27 444 MW
• Total production for Italy: 20 493 MW • Total production for Italy: 20 493 MW
• Net importation: 6 951 MW • Net importation: 6 951 MW
• 5 interconnection lines (220 kV and 380 kV) GREECE • 5 interconnection lines (220 kV and 380 kV) GREECE
(HVDC) (HVDC)
out service for maintenance out service for maintenance
Schneider Electric - Energy Automation – Technical Institute 126 Schneider Electric - Energy Automation – Technical Institute 126
Italy 2003: incident sequence Italy 2003: incident sequence

Series events: Series events:

• 03h25’21’’: successive loss of the 13 other • 03h25’21’’: successive loss of the 13 other
interconnection lines by overload protections interconnection lines by overload protections
• successive
i lloss off production
d ti units it b
by ‘l‘loss off • successive
i lloss off production
d ti units it b
by ‘l‘loss off
synchronism’ and ‘over- frequency’ protections synchronism’ and ‘over- frequency’ protections
• 03h28’00’’: BLACK-OUT • 03h28’00’’: BLACK-OUT

Separation line from Separation line from

European grid
Schneider Electric - Energy Automation – Technical Institute 127
European grid
Schneider Electric - Energy Automation – Technical Institute 127

Italyy 2003: frequency

q y evolution Italyy 2003: frequency
q y evolution

Schneider Electric - Energy Automation – Technical Institute 128 Schneider Electric - Energy Automation – Technical Institute 128
Defense plan
p Defense plan
p

● Network defense in 3 axes ● Network defense in 3 axes

prevention monitoring prevention monitoring

ultimate parry ultimate parry
preparation action preparation action

DETECTION LOAD SCHEDDING / DETECTION LOAD SCHEDDING /

UNMESHING UNMESHING
FIABILITY FIABILITY
AVAILABILITY manual or OLTC BLOCKING
AVAILABILITY manual or OLTC BLOCKING
PERFORMANCE automatic PERFORMANCE automatic
ACTIONS RECONSTRUCTION ACTIONS RECONSTRUCTION

‘N-k’ rule emergency production units ‘N-k’ rule emergency production units
management islanding management islanding

Schneider Electric - Energy Automation – Technical Institute 129 Schneider Electric - Energy Automation – Technical Institute 129

Defense p
plan Defense p
plan

two lines of defense

defense... two lines of defense
defense...

manual actions automatic actions manual actions automatic actions

fast re-dispatching units trips fast re-dispatching units trips
changes of topology OLTC changes of topology OLTC
close units starting automatic f/V load shedding close units starting automatic f/V load shedding
OLTC thermal units islanding OLTC thermal units islanding
manual load shedding (nuclear and classics) manual load shedding (nuclear and classics)

...to avoid incidents propagation and to plan ...to avoid incidents propagation and to plan
network reconstruction network reconstruction
Schneider Electric - Energy Automation – Technical Institute 130 Schneider Electric - Energy Automation – Technical Institute 130
Reconstruction plan
p Reconstruction plan
p

● First strategy : BUILD-UP ● First strategy : BUILD-UP

successful successful
islanding islanding

re feed the network « upward » before synchronizing most of

re-feed re feed the network « upward » before synchronizing most of
re-feed
genérators genérators
Schneider Electric - Energy Automation – Technical Institute 131 Schneider Electric - Energy Automation – Technical Institute 131

Reconstruction plan
p Reconstruction plan
p

● Second strategy : BUILD-DOWN ● Second strategy : BUILD-DOWN

re feed the network « downward » by creation of autonomous islands

re-feed re feed the network « downward » by creation of autonomous islands
re-feed
before synchronizing sub-networks together before synchronizing sub-networks together
Schneider Electric - Energy Automation – Technical Institute 132 Schneider Electric - Energy Automation – Technical Institute 132
Solutions for the future Solutions for the future

● DC links (HVDC) to stop disturbances propagation ● DC links (HVDC) to stop disturbances propagation

● PMU (Phasor
(Ph M
Measurement U
Units)
i ) iinstallation:
ll i ● PMU (Phasor
(Ph M
Measurement U
Units)
i ) iinstallation:
ll i
WAMS / WACS (Wide Area Measurement / Control System) WAMS / WACS (Wide Area Measurement / Control System)

● FACTS (flexible AC transmission system) for a better control of power ● FACTS (flexible AC transmission system) for a better control of power
fluxes fluxes

● System reconfiguration into energetically independant islands – cells ● System reconfiguration into energetically independant islands – cells
g
and distributed intelligence concepts
p g
and distributed intelligence concepts
p

● Embedded power generation ● Embedded power generation

Schneider Electric - Energy Automation – Technical Institute 133 Schneider Electric - Energy Automation – Technical Institute 133

Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling
Parameters affecting transmitted power Parameters affecting transmitted power
Risky situations Risky situations
Black Outs
Black-Outs Black Outs
Black-Outs

Studies to be carried out Studies to be carried out

Application: case studies Application: case studies

Schneider Electric - Energy Automation – Technical Institute 134 Schneider Electric - Energy Automation – Technical Institute 134
HV transmission network stabilityy studies HV transmission network stabilityy studies

Schneider Electric - Energy Automation – Technical Institute 135 Schneider Electric - Energy Automation – Technical Institute 135

When should a HV network stability When should a HV network stability

st d be carried o
study out?
t? st d be carried o
study out?
t?
power oscillations power oscillations

inter-area oscillations inter-area oscillations

rotor oscillations rotor oscillations

sub-synchronous
b h ffrequencies
i sub-synchronous
b h ffrequencies
i

evolutions of interconnected evolutions of interconnected

networks networks
shaft oscillations shaft oscillations
series compensators series compensators

new interconnections new interconnections

production units connection production units connection
Schneider Electric - Energy Automation – Technical Institute 136 Schneider Electric - Energy Automation – Technical Institute 136
Powers swings Powers swings

● Low frequency active power exchanges between generators or between ● Low frequency active power exchanges between generators or between
areas : areas :

inter-area inter-area
local modes local modes
modes modes

0.1
0 1 Hz 0.8
0 8HHz 0.1
0 1 Hz 0.8
0 8HHz
~ 0.7 Hz ~ 2.5 Hz ~ 0.7 Hz ~ 2.5 Hz

● Power System Stabilizer (PSS): regulation loop aiming to damp these ● Power System Stabilizer (PSS): regulation loop aiming to damp these
oscillations oscillations

Schneider Electric - Energy Automation – Technical Institute 137 Schneider Electric - Energy Automation – Technical Institute 137

Powers swings Powers swings

● Small-signal stability to determine des oscillanting modes that are naturally ● Small-signal stability to determine des oscillanting modes that are naturally
sustained (frequency and damping): sustained (frequency and damping):

●small disturbances (quasi-steady state) ●small disturbances (quasi-steady state)

●system linearization (state matrix) ●system linearization (state matrix)

● Determine PSS and AVR settings to damp the most problematic modes ● Determine PSS and AVR settings to damp the most problematic modes

Schneider Electric - Energy Automation – Technical Institute 138 Schneider Electric - Energy Automation – Technical Institute 138
Sub-synchronous
y frequencies
q Sub-synchronous
y frequencies
q

● Sustained shaft oscillations situations which appear spontaneously after ● Sustained shaft oscillations situations which appear spontaneously after
non-linearities: non-linearities:
●magnetic
magnetic circuit saturations ●magnetic
magnetic circuit saturations
●regulator limitations ●regulator limitations
●discrete events ●discrete events
● Resonance frequencies linked to electromechanical coupling between ● Resonance frequencies linked to electromechanical coupling between
machines and HV line series compensations machines and HV line series compensations

G G
5 Hz ~ 40-50 Hz 5 Hz ~ 40-50 Hz

● Sub-synchronous
Sub synchronous resonance analysis through dynamic simulation and ● Sub-synchronous
Sub synchronous resonance analysis through dynamic simulation and
small-signal study small-signal study
Schneider Electric - Energy Automation – Technical Institute 139 Schneider Electric - Energy Automation – Technical Institute 139

Interconnections evolutions Interconnections evolutions

● Islanded network study ● Islanded network study

● Production unit connection to interconnected network impact study ● Production unit connection to interconnected network impact study
● Sub-networks
Sub networks interconnection / synchronization preparation ● Sub-networks
Sub networks interconnection / synchronization preparation

● Determination of low frequency modes: ● Determination of low frequency modes:

●new modes ●new modes
●impacts on pre-existing modes ●impacts on pre-existing modes

Any HV network complexity increase will potentially lead to the Any HV network complexity increase will potentially lead to the
apparition of new oscillation modes. apparition of new oscillation modes.

● Analysis of induced disturbance through dynamic simulation and small- ● Analysis of induced disturbance through dynamic simulation and small-
signal
i l study
t d signal
i l study
t d

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 Production units stabilityy studies Production units stabilityy studies

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What kind of study should be carried out What kind of study should be carried out
for unit
nit connection? for unit
nit connection?
Response to sudden events Response to sudden events
short-circuits; voltage drops; loss of load / production short-circuits; voltage drops; loss of load / production
CAPABILITY TO CONSERVE SYNCHRONISME / RISK OF MIS-COUPLING CAPABILITY TO CONSERVE SYNCHRONISME / RISK OF MIS-COUPLING

Behavior to slow variations Behavior to slow variations

variations of voltage; frequency; load variations of voltage; frequency; load
VALIDATION / ADJUSTMENT OF U/Q AND f/P REGULATIONS VALIDATION / ADJUSTMENT OF U/Q AND f/P REGULATIONS

Oscillation modes study (Eigen modes / inter-area modes) Oscillation modes study (Eigen modes / inter-area modes)
power swings; resonances power swings; resonances
DAMPING OF LOW FREQUENCY OSCILLATIONS DAMPING OF LOW FREQUENCY OSCILLATIONS

Production unit islanding Production unit islanding

operation
p on auxiliaries; loss of the network; voltage
g return operation
p on auxiliaries; loss of the network; voltage
g return
CAPABILITY OF NETWORK SUPPORT / BLACK-START CAPABILITY OF NETWORK SUPPORT / BLACK-START

Schneider Electric - Energy Automation – Technical Institute 142 Schneider Electric - Energy Automation – Technical Institute 142
Connection to transmission network Connection to transmission network

● DYNAMIC STABILITY ● DYNAMIC STABILITY

The owner must demonstrate the production unit capability to conserve The owner must demonstrate the production unit capability to conserve
synchronism: synchronism:
●Standard voltage drop ●Standard voltage drop
●minimum FCCT ●minimum FCCT

● STATIC STABILITY ● STATIC STABILITY

S ll i
Small-signal
l stability:
t bilit S ll i
Small-signal
l stability:
t bilit
●Determination of Eigen modes (, ) ●Determination of Eigen modes (, )
●Determination of g
gain and p
phase margins
g ●Determination of g
gain and p
phase margins
g
Stabilization after a voltage set point step: active power must be quickly Stabilization after a voltage set point step: active power must be quickly
stabilized stabilized

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Connection to transmission network Connection to transmission network

● NETWORK SUPPORT (Ancillary-Services) ● NETWORK SUPPORT (Ancillary-Services)

The owner of a ‘Controlling Unit’ must demonstrate the production unit The owner of a ‘Controlling Unit’ must demonstrate the production unit
capability to mobilize its active and reactive powers primary reserves: capability to mobilize its active and reactive powers primary reserves:
●Stability after a frequency variation (validation of f/P primary control) ●Stability after a frequency variation (validation of f/P primary control)
●Reactive droop, reactive power diagram (validation of U/Q primary control) ●Reactive droop, reactive power diagram (validation of U/Q primary control)

● ISLANDING ● ISLANDING
Th production
The d ti unitit mustt be
b able
bl to
t operate
t on its
it auxiliaries
ili i andd tto ensure Th production
The d ti unitit mustt be
b able
bl to
t operate
t on its
it auxiliaries
ili i andd tto ensure
voltage return on the network voltage return on the network

>>> The unit have to support the transmission network >>> The unit have to support the transmission network

Schneider Electric - Energy Automation – Technical Institute 144 Schneider Electric - Energy Automation – Technical Institute 144
Connection to distribution network Connection to distribution network

● DYNAMIC STABILITY ● DYNAMIC STABILITY

The owner must demonstrate the production unit capability to conserve The owner must demonstrate the production unit capability to conserve
synchronism in case of short
short-circuit
circuit or voltage drop occurring on the synchronism in case of short
short-circuit
circuit or voltage drop occurring on the
network network

If not, the unit must disconnect from the grid in case of disturbance on the If not, the unit must disconnect from the grid in case of disturbance on the
distribution network distribution network

● ISLANDING ● ISLANDING
The owner may y carryy out a dynamic
y stabilityy studyy if he wishes to island The owner mayy carryy out a dynamic
y stabilityy studyy if he wishes to island
after a disconnection after a disconnection

>>> The
Th unitit mustt nott disturb
di t b the
th di
distribution
t ib ti network
t k >>> The
Th unitit mustt nott disturb
di t b the
th di
distribution
t ib ti network
t k

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Stability studies for Oil&Gas type Stability studies for Oil&Gas type
industries industries

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 Why
y a stabilityy studyy for MV motors? Whyy a stabilityy studyy for MV motors?
start / re-acceleration start / re-acceleration
capability capability
~ ~

source change-over source change-over

fast load-shedding M M M fast load-shedding M M M

~ ~ ~ ~

behavior in case of behavior in case of

short-circuit M M M M M short-circuit M M M M M

~ ~

M M M assistance to control/command M M M assistance to control/command

automatisms definition automatisms definition
Schneider Electric - Energy Automation – Technical Institute 147 Schneider Electric - Energy Automation – Technical Institute 147

Start / re-acceleration Start / re-acceleration

i d ti motors
induction t t
torque & currentt curves i d ti motors
induction t ttorque & currentt curves
Voltage Voltage

Speed Speed

I / In  / n I / In  / n

time time
1 1 1 1

0 N / Nsynchro 1 0 N / Nsynchro 1
Torque Torque

A deep voltage drop can lead to A deep voltage drop can lead to
motor stall Current motor stall Current

time time

Schneider Electric - Energy Automation – Technical Institute 148 Schneider Electric - Energy Automation – Technical Institute 148
Source change-over
g Source change-over
g

● Automatic change-over operation induce motors slow-down during the ● Automatic change-over operation induce motors slow-down during the
change-over, followed by a load increase for the new source change-over, followed by a load increase for the new source

A
Voltage A
Voltage
B B

DA DB DA DB

Speed Speed
DC DC

M M M M M M M M M M

takeover by main A takeover by main A

time time

Schneider Electric - Energy Automation – Technical Institute 149 Schneider Electric - Energy Automation – Technical Institute 149

Source change-over
g Source change-over
g

● If the voltage drop is too deep, the driving torque decreases... ● If the voltage drop is too deep, the driving torque decreases...

V lt
Voltage V lt
Voltage

Voltage Voltage

Torque Torque

Torque Torque

time time time time

successful takeover : motors re-accelerate and unsuccessful takeover : acceleration torque is successful takeover : motors re-accelerate and unsuccessful takeover : acceleration torque is
voltage increase back to normal insufficient to re-accelerate motors voltage increase back to normal insufficient to re-accelerate motors

● ...motors don
don’tt re
re-accelerate
accelerate ● ...motors don
don’tt re
re-accelerate
accelerate
>>> load-shedding plan / fast load-shedding >>> load-shedding plan / fast load-shedding
Schneider Electric - Energy Automation – Technical Institute 150 Schneider Electric - Energy Automation – Technical Institute 150
Short-circuit / voltage
g drop
p Short-circuit / voltage
g drop
p

● Voltage drop  motors loose driving force ● Voltage drop  motors loose driving force

● Short-circuit
Sh i i  motors braking
b ki ● Short-circuit
Sh i i  motors braking
b ki

●  induction motors may stall if acceleration torque is too low ●  induction motors may stall if acceleration torque is too low

●  synchronous motors may loose synchronism if the disturbance goes on ●  synchronous motors may loose synchronism if the disturbance goes on
for too long for too long

>>> p
protection p
plan validation / study
y >>> p
protection p
plan validation / study
y

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Introduction: Issues and definitions Introduction: Issues and definitions

Theoretical reminder Theoretical reminder
Regulators modeling Regulators modeling
Parameters affecting transmitted power Parameters affecting transmitted power
Risky situations Risky situations
Black Outs
Black-Outs Black Outs
Black-Outs
Studies to be carried out Studies to be carried out

Application: case studies Application: case studies

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 Static stability: Static stability:
theoretical study theoretical study

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Steady
y state calculation Steadyy state calculation
A A
Transmittable powers Transmittable powers
PnA = 15000 MW VA = 415 kV PnA = 15000 MW VA = 415 kV
GA PmaxAR = .3000 MW. MW GA PmaxAR = .3000 MW. MW
RA = 7.5 % A = .5.51° . RA = 7.5 % A = .5.51° .
PmaxBR = .2400 MW. MW PmaxBR = .2400 MW. MW
PchA = 9000 MW PchA = 9000 MW
PmaxAB = .3800 MW. MW PmaxAB = .3800 MW. MW
PgA = .10815 MW
. MW PgA = .10815 MW
. MW

R R
PiR = .461 MW. MW PiR = .461 MW. MW
PnB = 12000 MW PnB = 12000 MW
RB = 8 % RB = 8 %
f = 50 Hz f = 50 Hz

Q=0 PnR = 231 GW Q=0 PnR = 231 GW

RR = 14 % RR = 14 %
VR = 400 kV VR = 400 kV
Q=0 Q=0
GB R = 0°
Transmitted powers
p
GB R = 0°
Transmitted powers
p
PAR = .288 MW. MW PAR = .288 MW. MW
B PBR = .-749 MW. MW B PBR = .-749 MW. MW
VB = 380 kV PAB = .1527 MW. MW VB = 380 kV PAB = .1527 MW. MW
B = .-18.19°
. B = .-18.19°
.
PchB = 13000 MW PchB = 13000 MW
PgB = .10724 MW
. MW PgB = .10724 MW
. MW
Schneider Electric - Energy Automation – Technical Institute 154 Schneider Electric - Energy Automation – Technical Institute 154
Disturbance: load variation at A Disturbance: load variation at A

PnA = 15000 MW A PnA = 15000 MW A

RA = 7.5 % GA PchA = 5000 MW RA = 7.5 % GA PchA = 5000 MW
A = .4000 .MW/Hz
MW/Hz PgA = .10415 MW
. MW A = .4000 .MW/Hz
MW/Hz PgA = .10415 MW
. MW

R R
PnB = 12000 MW
PiR = .-2839 . MW
2839 MW PnB = 12000 MW
PiR = .-2839 . MW
2839 MW
RB = 8 % RB = 8 %
B = .3000 .MW/Hz
MW/Hz B = .3000 .MW/Hz
MW/Hz
f = .50.1 Hz
. Hz f = .50.1 Hz
. Hz

PnR = 231 GW PnR = 231 GW

RR = 14 % RR = 14 %
GB R = .33 GW/Hz
. GW/Hz GB R = .33 GW/Hz
. GW/Hz

B B
PchB = 13000 MW PchB = 13000 MW
PgB = .10424 MW
. MW PgB = .10424 MW
. MW

Schneider Electric - Energy Automation – Technical Institute 155 Schneider Electric - Energy Automation – Technical Institute 155

Dynamic stability: Dynamic stability:

case study with PSAF/STAB case study with PSAF/STAB

14.4 MW steam turbine connection to 20 kV public 14.4 MW steam turbine connection to 20 kV public
distribution network distribution network

Schneider Electric - Energy Automation – Technical Institute 156 Schneider Electric - Energy Automation – Technical Institute 156
Installation single-line
g diagram
g Installation single-line
g diagram
g

Schneider Electric - Energy Automation – Technical Institute 157 Schneider Electric - Energy Automation – Technical Institute 157

Regulation
g models Regulation
g models

Th turbine
The t bi and
d its
it speed
d regulation
l ti Th turbine
The t bi and
d its
it speed
d regulation
l ti

included in the included in the

generator’s model generator’s model

standard model standard model

from the software from the software
library library

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Regulation
g models Regulation
g models
Exciter and AVR Exciter and AVR

standard model from the standard model from the

software
ft lib
library software
ft lib
library

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Dynamic
y simulation: short-circuit Dynamic
y simulation: short-circuit

820 ms 820 ms
830 ms 830 ms
2.100 s 2.100 s

short-circuit duration short-circuit duration

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Dynamic
y simulation: loss of the network Dynamic
y simulation: loss of the network

Electrical Active Power Electrical Active Power

Mechanical Power Mechanical Power

Schneider Electric - Energy Automation – Technical Institute 161 Schneider Electric - Energy Automation – Technical Institute 161

To improve
p yyour knowledge
g ... To improve
p yyour knowledge
g ...

P. Kundur : « Power System Stability and P. Kundur : « Power System Stability and
Control », McGraw-Hill, 1994 Control », McGraw-Hill, 1994

RTE : Mémento de la sûreté du système électrique, édition 2004 RTE : Mémento de la sûreté du système électrique, édition 2004

Techniques de l’Ingénieur
l Ingénieur : D4092 “Réseaux
Réseaux d’interconnexion
d interconnexion et de Techniques de l’Ingénieur
l Ingénieur : D4092 “Réseaux
Réseaux d’interconnexion
d interconnexion et de
transport : réglage et stabilité“ transport : réglage et stabilité“

UCTE : « FINAL REPORT off the

th Investigation
I ti ti Committee
C itt on the
th 28 UCTE : « FINAL REPORT off the
th Investigation
I ti ti Committee
C itt on the
th 28
September 2003 Blackout in Italy », 2004 September 2003 Blackout in Italy », 2004

Schneider Electric - Energy Automation – Technical Institute 162 Schneider Electric - Energy Automation – Technical Institute 162