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Technologies Enabling a Stronger, Smarter
and Greener Grid
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21TH JAN 2020
Pump Storage solutions
CFSM – Converter Fed Synchronous Machine
Shanthakumar M S, Technology Manager- HVDC & FACTS
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Electrical supply network with renewable energy sources
The grid’s architecture change
Major changes
▪ Increased RE mix, Wind and solar energy in the whole network
▪ Intermittent renewable energy sources
▪ Grid stability, security and Energy storage
▪ Reduction of CO2 emission, generation mix
• Change of grid architecture- Inertia, Reactive power, Ramp
up/down
• Calm, Cloud, Rain seasonal variations and climate change
Opportunities
▪ Transport of electricity over very long distances
▪ Integration of renewable energies (storage, smart grids, etc.)
▪ Harmonization of standards and grid codes
▪ Ancillary services
January 20, 2020 Slide 2
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Hydro Pump Storage
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Applications of energy storage
Integration of renewable resources Ancilliary services System adequacy
Renewable Generated Supply Power
Power Absorb Power f [hz] Load
Supply Power Absorb power
Power 50.02
50.00
49.98
Absorb Power
Supply power
Energy stored Energy stored
t [sec] in ESS
in ESS
Charge Discharge t [hrs]
Charge Discharge Charge Discharge t [sec]
t [sec>min]
Power quality Energy resiliency
Energy storage systems
Short disruption Supply power Scheduled power
Supply Power
consumption
Voltage Load
Power Electricity supply failure
Actual
Supply power power Absorb power
t [sec>min] consumption t [sec]
Energy Energy
t [ms] stored
Energy stored
in ESS in ESS
stored
in ESS
Discharge
Discharge Discharge
Charge
January 20, 2020 Slide 4
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Hydro Pumped Storage
Network Generalities
Renewable energy (wind, solar) is
⮚ extremely volatile - difficult to predict - non dispatchable
Grid stability becomes uncertain with large amount of intermittent wind
and solar
⮚ Need for flexible, fast and big residual last compensation units
Base load power plants production cost increases
⮚ Not basically designed for power control, reduction of operation
efficiency
⮚ Increase of maintenance effort and cost
The larger the amount of wind and solar in the generation mix,
the larger the problems in the grid
The capacity of renewables is increasing rapidly
▪ Storage technologies are needed
▪ Hydro Pumped Storage solution of choice for large storage
January 20, 2020 Slide 5 Confidential – For Discussion only
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Hydro Pumped Storage
Limitations of Conventional Solution
Conventional, fixed speed systems: Disadvantages
– No ability to vary the rotational speed
• Pump mode only possible at fixed power
• Efficiency not always optimal, especially at
partial load operation
– Start is time consuming, especially in pump operation
• Increasing difficulties to participate in the highly dynamic energy
market
New pumped storage technologies: Targeted Requirements
– Pumping shall be possible at variable power
– Short start-up, stop and reversing times
– Increased efficiency through variable speed
– Grid code compliance
January 20, 2020 Slide 6 Confidential – For Discussion only
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Hydro Pumped Storage
New Pumped Storage Technologies
New Requirements for Pumped Storage Doubly Fed Induction Machine (DFIM)
Flexible operation is requested – Induction machine (ASM) controlled by AC
– Fast capability to supply/ absorb large amount of energy Excitation Frequency Converter
– Fast capability to change operation mode – Solution used for large variable speed units
– Short start-up time – Complex solution with limited speed variation range
Ancillary services
– Improved frequency regulation capability Converter Fed Synchronous Machine (CFSM)
– Primary and secondary regulation also in pumping mode – Synchronous Machine (SM) driven by Full Size
Efficiency improvement Frequency Converter connected to stator windings
– Optimum operation point of the pump-turbine – Advanced solution best fitting for new pumped storage
requirements
Grid code compliance
– Overcoming DFIM shortcomings
– Latest Grid Code requirements have to be fulfilled
Power electronics makes Hydro Pumped Storage more flexible and improve its efficiency
January 20, 2020 Slide 7
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Variable Speed Hydro Pumped Storage
Converter Fed Synchronous Machine
Converter Fed Synchronous Machine Typical Operation Range CFSM Characteristics
Synchronous Machine (SM) driven by Full
Size Frequency Converter
– Higher operation flexibility
– Maximized use of hydraulic site characteristics
Simple concept
– Standard Hydro equipment incl. advanced
Frequency Converter
– Full Size Power Converter
Maintenance optimized solution
– Use of well proven power station equipment
– Low Converter maintenance
CFSM – Simplified System Complexity, Higher System Availability, Low Maintenance
January 20, 2020 Slide 8
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ABB Converter Fed Synchronous Machine Solution
Simplified Single Line Diagram
January 20, 2020 Slide 9 Confidential – For Discussion only
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ABB Full Converter Technology
Frequency Converter Basic Characteristics
Basic Control Diagram Active Power Control Characteristics
Control of active Power flow independant from reactive power
Active power to be transferred through frequency converter
P Very fast active Power flow control
~
~
~
U1 U2
Q1 Q2 Reactive Power Control Characteristics
~
~
~ Independent controllers on each converter sides
Extremely fast reaction time (range of ms)
January 20, 2020 Slide 10
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Converter Fed Synchronous Machine
CFSM – Operation Diagram
CFSM Main Characteristics Transition Diagrams
Very fast reaction time from any operation point
Turbine
– Very short start – stop time
mode +
– Independent active and reactive power controllers STATCOM
Fast inversion of operation
– Smooth pass through «Stop», with contribution from hydraulic STATCOM
(machine
– No need for physical Stop – Phase reversal by the converter Stop
@
standstill)
Reactive Power Compensation (RPC) with machine at standstill
– Advanced STATCOM functionalities
Pumps
– Reduced maintenance efforts +
Provision of Virtual Inertia for Grid Frequency Support STATCOM
– Optimized and controlled Grid Frequency support
Converter Fed Synchronous Machine – Most Flexible Operation
January 20, 2020 Slide 11
Available power from the grid
— Machine 1 in operation
Machine 2 in operation
Converter Fed Synchronous Machine Machine 1 or both machines in operation
Solution of Choice for Efficient Pumped Storage – Maximal use of water conditions and resources
CFSM Highest Flexibility Converter Fed Synchronous Machine
Very large speed variation range
- Maximal use of hydraulic system – Operation extended to maximal head
variation
- Operation extension to very low partial load in turbine and pump modes
Highest operation flexibility even in pump mode
- Best support for renewables fluctuations, even very large
- Excellent Grid stability support – Very fast control reaction time
Maximized Power Station Operation Time
- More operation time – More revenues
- Less start-stop sequences - Reduced stress on machine
Participation in highly dynamic energy market
- Increased revenue capabilities
CFSM – Most Valuable Pumped Storage Solution for Integration of Large Amount of Renewables
January 20, 2020 Slide 12
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Converter Fed Synchronous Machine
The needed efficiency
Maximal Operation Flexibility Optimal hydraulic efficiency at different power
Power-Efficiency
More renewable integration without jeopardize grid curve by variable
stability speed
Improved efficiency of base load plants
Optimized of use of water resources
More energy transported on the grid over long
distances
Moreover:
Variable speed solution allows to operate on
optimal hydraulic efficiency across wide power
range
ABB CFSM converter system efficiency exceeding
98,7%
Converter Fed Synchronous Machine – Increased renewable integration with optimized efficiency
November 7, 2018 Slide 13
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Converter Fed Synchronous Machine Solution
Possibilities and characteristics
Reactive power control functionality of frequency converter
– Frequency converter provides or absorbs reactive power on the grid
side
– Machine can be designed for pure active power operation (cos phi
1) ⮚ cost savings
– Excellent grid support capabilities
• Reactive current injection >1pu during grid fault
– Very high dynamic reactive power control (order of
magnitude of ms)
– Reactive power compensation with machine at standstill
• Very low losses
• Reduced maintenance cost
STATCOM = Static Synchronous Compensator
January 20, 2020 Slide 14
Confidential – For Discussion only
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ABB Hydro SFC Light
Grid Code Requirement - Summary for CFSM
Requirements Converter fulfillment
Frequency stability Independent grid side frequency control
Independent P/Q control
Fault ride through Provision for reactive current >1pu
No risk for loss of machine synchronism
Fast and wide power control capability
Active power frequency response
Limitation by hydraulic system
Voltage stability Large Reactive Power Control capability
Very fast independent P/Q control
Reactive power capability
Direct impact from requirements on converter size
Large possible contribution with machine electrically decoupled from the
Virtual Inertia
grid
Very good capability with machine electrically decoupled from the grid,
Black Start
power supply for auxiliaries needed
January 20, 2020 Slide 16
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ABB Hydro SFC Light
Advanced Power Electronics Technology for Converter Fed Synchronous Machine Solution
Modular Multilevel Converter (MMC) ABB Hydro SFC Light Converter
– Scalability in Voltage and Power Ratings – Converter Rating up to 400+ MW
– Redundancy in power part for maximum availability
– Modular phase leg construction for footprint optimization
– Very high converter efficiency >98.7%
– Full torque available from zero rpm – very fast start-up time with pump in water
Technology Dedicated for Highly Demanding Applications
Leveraging technology, control and protection concepts developed for
– Large STATCOMs providing power grid stability and preventing black-outs or assuring
power quality in demanding and sensitive industrial productions
– Static Frequency Converters for energizing key rail transportation systems and pump
hydro storage systems
Converter Fed Synchronous Machine – Robust Solution for Highly Demanding Applications
January 20, 2020 Slide 17
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ABB Hydro SFC Light
Direct Converter Topology based on SFC Light MP Modular Multilevel Converter
January 20, 2020 Slide 18 Confidential – For Discussion only
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ABB Hydro SFC Light for Converter Fed Synchronous Machine
Summary
Highly efficient and scalable converter solution
– Converter output voltage in the normal range of generators
– High power capabilities
– Very high efficiency > 98.7%
High availability and safety
– Conventional Power Station Equipment including a Converter
– Possible built in redundancy in power part
Higher operation flexibility
– Very quick response from any operating point
– Wider operating range
– Reactive power always available, even at machine standstill
– Lower system complexity, use of standard synchronous machines
and transformers
– Excellent grid support even in the most severe disturbances with
advanced functionalities
January 20, 2020 Slide 20 Confidential – For Discussion only
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Variable Speed – Converter Fed Synchronous Machine
Conclusions
STRONGER SMARTER GREENER
Superior grid support Active power control in pump Supporting high renewable integration in the
- Reactive Power Control operation over a very wide grid
functionalities range Optimized use of water for performing primary
- LVRT regulation
- Primary Frequency
response Fast and smooth transition Improved overall generation system efficiency
- Virtual Inertia between operation modes Very high converter efficiency exceeding
98,7%
Standard Hydro equipment incl.
First in class reliability advanced Frequency Converter
- Modular Solution up to for max. flexibility, reliability and
300+ MW revenues
- High Reliability with inbuild Low maintenance cost
redundancy
Retrofit friendly
CFSM variable speed solution – The Pumped Hydro technology for today and tomorrow Power Grids
January 20, 2020 Slide 21
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Reference Project Grimsel 2
A Milestone in the Alps – 100 MVA Full Converter
Slide 22 20, 2020
January
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Grimsel 2 Power Plant
Project introduction
Grimsel 2 Pumped Storage Power Plant – Group 1 (existing)
Unit type Synchronous ternary group
BBC Generator / Motors
Rated values 100 MVA / 13.5 kV
Rated power ~80 MW / ~90 MW
turbine- / pump mode
Rated speed 750 rpm
Rated head 400 m
Block transformer 100 MVA, 220 kV / 13.5 kV (existing)
Construction 1973 - 1980
January 20, 2020 Slide 23 Confidential – For Discussion only
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Grimsel 2 – Variable Speed Pumped Storage CFSM
Project introduction
Simplified project requirements
KWO has to produce power control
Power control in pump mode is not possible with fixed speed machines
– Only achievable by generating with valuable water from another
machine
Power control in pump mode only possible with variable speed
operation
Variable Speed not necessary for Turbine operation
January 20, 2020 Slide 24 Confidential – For Discussion only
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Grimsel 2 – Variable Speed Pumped Storage CFSM
Full Converter - Operation Modes
Variable speed Grimsel 2
– PCS 8000 converter rated power : 100 MVA
– Pump power variation: 60…100 MW
– Start-up in pump mode via frequency converter
– Unit breaking via frequency converter
Possible operation modes
– Turbine mode (without converter)
– Pump operation with / without converter
– Static reactive power source ±100 Mvar (Converter)
System in commercial operation
– Variable speed pump operation ~40%
– Reactive power compensation ~16%
January 20, 2020 Slide 25 Confidential – For Discussion only
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Grimsel 2 – Variable Speed Pumped Storage CFSM
A Milestone in the Alps, A Reference for the World
Summary and conclusion
– KWO does not waste valuable water for generating primary control
energy
– Energy efficient operation of pump
– Reference for pumped storage solutions of the future
– Contributes to stabilizing the net
– Optimal back-up solution for integration of renewable energy sources
– Dynamic support of voltage and frequency will become more
important
January 20, 2020 Slide 26 Confidential – For Discussion only
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Reference Project Malta Oberstufe - Austria
Entrance in a New Era – Scalable and High Efficient MMC Converter Technology
Slide 27 20, 2020
January
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Reference – Malta Oberstufe, Austria
Retrofit for variable speed operation with CFSM – 2x 80 MW
Customer needs
Maximal operation flexibility
Removal of energy consuming hydraulic short circuit
Fulfillment of new grid code requirements
High system efficiency, reliability and availability
Start of operation scheduled Q1/2021
Customer’s benefits
Maximized operation flexibility and participation to highly dynamic
market
Support of Integration of Renewables in Germany
Extended revenues with provision of primary control even in pump
mode
Increased operation efficiency
Grid Code Fully fulfilled
Redundancy in converter for safe operation during winter
January 20, 2020 Slide 28
January 20, 2020 Slide 29
