Asigurarea calitatii serviciului de alimentare cu energie
electrica
Laborator nr. 4
Evaluarea factorilor care determină în mod direct calitatea
serviciului de alimentare cu energie electrică .
What is power quality? Defining power quality
Ensuring the continuity of supply Enhancing the electrical parameters Optimizing the commercial quality
Consumers can utilize electricity from The technical shape of voltage waveform and The speed and accuracy with which power
the supplying network efficiently, without all electrical parameters are according to quality problems are handled
interference or interruption. Suppliers can specifications and defined limits
generate power consistently over a planned
life expectancy
Power quality is a measure of the availability, quality and efficiency of the electricity being supplied and utilized on a
consistent basis
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Causes of poor power quality
Result of high reactive power in the network
Low power factor Reduces the capacity of the system for productive work
01 Overloads electrical supply systems like cables, transformers etc, causing malfunctioning or breakdown
Attracts penalties from utilities
Caused by non-linear loads, e.g. electronic equipment, drives, fluorescent lights, computers and uninterrupted
power supplies
Harmonics
Increases energy losses and can leads to equipment malfunctioning or damage
02
Result of fast load variations, e.g. arc furnaces or welding loads, or background voltage variations
Voltage variation Can lead to inefficient system operation, inability of loads to run and damage of electrical equipment
03
Caused by single phase loads, like trains, office equipment or lighting systems
Load imbalance Can lead to excessive voltage unbalance, damaging equipment, overload of individual phases and safety issues
04 HITACHI ABB POWER GRIDS
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The changing power landscape | Many drivers one common need
Generation Consumers
Increasing energy production Increasing power consumption
Integration of renewables Need for good New grids in emerging markets
power quality
Faster and stronger transportation
Deal with distributed generation
systems
Transmission & Distribution
Changing regulations Energy trading Reversible
Aging infrastructure
grid code compliance between regions power flow
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Modern networks and power quality challenges
Power Electronics (VFD, UPS etc.)
Wind Captive generation (solar)
Industry
Power variations due to E-Mobilityation (including railways)
weather-dependent output
Reactive power needs
restrict capacity utilization Sensitive loads (data servers, medical devices etc.)
Transmission Infrastructure
Harmonic pollution
Accumulation of all power
quality issues
Lightning and switching
surges
Distribution / Domestic loads (computers, SMPS, E-chargers etc.)
Microgrids
Solar HVDC converters
* Prosumers = Producers + consumers of energy, e.g. factories and buildings with rooftop solar PV installation HITACHI ABB POWER GRIDS
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How to achieve good power quality
Analyze Optimize Realize
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Your benefits | Widest range of products, services and solutions
Consulting BENEFITS
FACTS Sustainability
Optimized revenue Enhanced grid
lower running costs reliability and stability
Shunt reactors
Capacitors and filters Ease of integration
Deferral of grid Reliability
or realization of
upgrades
integration
Active filtering solutions
Voltage conditioning and regulation
Reduced penalties
New revenue from Productivity
from harmonic pollution
ancillary grid services
and demand peaks
Monitoring, protection and controls
Volt-VAr management
Improved productivity Increased
Cost
and saving on self-consumption
maintenance costs of renewables optimization
Energy storage
Surge arresters and surge
capacitors
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Power quality portfolio
Voltage level Segment Products and solutions
1200 kV
Generation and
transmission Capacitor banks Passive Filters HV surge arresters
Capacitor units FACTS
Energy intensive
industry, utilities
Capacitor units Capacitor banks Passive Filters HV surge arresters STATCOM
Industry and
large commercial Modular capacitor Motor surge Pole mounted
Capacitor units protection MV surge arresters
banks capacitor banks
Small industrial,
commercial and
residential Capacitors Automatic Stepless Active harmonic
capacitor reactive power filters Battery energy
200 V storage
banks compensators
We offer power quality solutions for all segments, across all voltage levels
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Power quality challenges for E-Mobility
Typical power quality challenges
Electrification of Everything
Electric vehicles (EVs) like e-cars, e-busses and electric ferries
generally use rechargeable batteries
Chargers for these batteries use AC-to-DC converters that can
cause:
Harmonic pollution
Low power factor
Voltage dips and peak load
Voltage dips may be significant in case of electrified rail networks,
along with sudden and large reactive power demand and load
imbalance
Voltage surges are a risk for electric trains
need maximum capacity utilization of grid
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Power quality challenges for Industries
Typical power quality challenges
Rapid replacement of electromechanical equipment by power
electronics in industries
e.g. VFDs replacing gear drives for motors
Such electronic loads
power quality)
can generate multiple harmonics and draw significant reactive
(e.g. solar photovoltaic
Exchange of excess output of this generation with grid can cause
voltage variations and harmonic pollution, reactive power related
issues
Industries face penalties or disconnection risks wrt poor power
quality due to stricter regulations of grid utilities
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Power quality challenges for Buildings and Infrastructure
Typical power quality challenges
Like in industries, electronic loads also dominate buildings and other
infrastructure
Power quality issues like harmonic pollution, voltage variation and
load imbalance can affect their performance, like:
Improper operation of loads, e.g. elevators, escalators, HVAC,
Maloperation or incorrect output of equipment (e.g. medical
diagnostic instruments)
Malfunction of servers of data storage facilities
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Power quality challenges for HVDC
Typical power quality challenges
High voltage direct current (HVDC) lines transfer electricity over long
distances with significantly less energy losses
Electricity is generated in alternating current (AC) form, and
converted to DC for transmission through power electronic
converters
For distribution, electricity is again converted from DC to AC
This AC-DC-AC cycle can introduce some power quality issues, e.g.
Harmonic pollution
Reactive power demand
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Power quality challenges for Renewables
Typical power quality challenges
Output of renewables like solar and wind farms depends on climatic
conditions, and thus, is highly variable.
If this output cannot match the demand in grid, there can be large
variations in voltage.
Wind power
Wind turbines use induction generators directly grid-coupled or
converter technology
For optimal operation, they may need external reactive power
support
In addition, the harmonic signature at wind farm connection point
may be too high, and not in line with grid regulations.
Solar power
Solar inverters have a maximum kVA-rating they are designed for.
If reactive power demand is high, the capacity of inverter to deliver
active power is reduced
Less active power output = less revenues!
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