The Application of Power Electronics to the Alberta Grid

Transcription

1 The Application of Power Electronics to the Alberta Grid Peter Kuffel, Michael Paradis ATCO Electric APIC May 5, 2016

2 Power Electronics Semiconductor devices used in power transmission systems Types: Thyristor Insulated Gate Bipolar Transistor (IGBT) Applications: Flexible AC Transmission Systems (FACTS) High Voltage Direct Current (HVDC)

3 Distinguishing Properties Diode Turn On => Positive Voltage (uncontrolled) Turn Off => Negative Voltage (uncontrolled) Thyrsitor Turn On => Positive Voltage & Gate Pulse(controlled) Turn Off => Negative Voltage (uncontrolled) IGBT Turn On => Positive Voltage & Gate Signal(controlled) Turn Off => Negative Voltage OR Removal of Gate Signal (controlled)

4 Applications FACTS Increase the reliability of AC grids, improve efficiency and reduce power delivery costs. fast voltage regulation, increased power transfer over long AC lines, damping of active power oscillations, control of power flow in meshed systems. Configurations: Shunt connected: Static Var Compensators (SVC) Static Compensators (STATCOM) Series connected: Thyristor Protected Series Capacitors (TPSC) Thyristor Controlled Series Capacitors (TCSC)

5 Static Var Compensator (SVC) Variable shunt impedance Basic electrical components: Coupling transformer Thyristor Controlled Reactor (TCR) Thyristor Switched Capacitor (TSC) Harmonic Filters, required if TCR used Thyristor Switched Reactor (TSR)

6 Static Var Compensator (SVC) Control features: Voltage control Reactive power control Power oscillation damping

7 Static Compensator (STATCOM) Voltage Source Converter (VSC) based device Electrical similarities to synchronous condenser Converter has both capacitive and inductive capability Basic electrical components Coupling transformer Phase reactor IGBT modules

8 Static Compensator (STATCOM) Controllable voltage behind a reactance Voltage source is created by charging/discharging capacitors using the IGBTs Amplitude of voltage behind the reactance greater than system voltage => capacitive Amplitude of voltage behind the reactance is less than system voltage => inductive Fast switching and precise control of IGBTs provides response times better than SVC

9 Applications - HVDC Bulk power transfer Interconnection of asynchronous grids Interconnection of grid of different frequency Fast accurate control of power flow Configurations: Line Commutated Converters (LCC) => Thyristor based Voltage Source Converters (VSC) => IGBT based

10 Line Commutated HVDC

11 Commutation Thyristors are series connected to create a valve Thyristor valves are arranged in groups (6- pulse groups) R S T U d Each valve is turned on (fired) in sequence When a valve is fired it begins to conduct and current is transferred (commutated) from the outgoing vale to the incoming valve. R S T U d By firing in sequence, the ac is converted to dc (rectifier) or the dc is converted to ac (inverter) By controlling the precise time that each valve is fired, the DC voltage across the group is varied R S T U d

12 HVDC Power Flow Rectifier Inverter UdR Id R UdI The DC current flowing between rectifier and inverter is only a function of the difference between the two DC voltages (UdR and UdI) and the resistance between them (dc line resistance R) The DC power at the rectifier is UdR * Id To control DC power flow, need to control the voltage at the two terminals

13 LCC HVDC Characteristics Current flow is unidirectional Power reversal => Voltage polarity flip Conversion process generates harmonics AC & DC filters required Commutation process requires an ac voltage Commutation becomes more difficult as strength of the ac system (short circuit level) decreases SCR <2.0 deemed low

14 Voltage Source Converter (VSC) Two Level Converter Topology Many series connected devices connected All devices in one arm must switch simultaneously PWM switching Filtering required Higher losses

15 VSC Modular Multilevel Converter Topology

16 VSC HVDC Characteristics Can be operated in AC grids with extremely low short-circuit levels Passive systems Black start capability. Independent control of active and reactive power Flexible with respect to reactive power and can provide AC voltage control. No harmonic generation No AC or DC filters required Current flow through converter is bi-directional

17 Power Electronics in Alberta Grid HVDC EATL 1000 MW/500 kv WATL 1000 MW/500 kv McNeill 150 MW/40 kv Conventional SVC 7 In Service 1 Planned STATCOM 3 In Service

18 SVCs North West +/- 30 MVAR SVCs for local area stability Cranberry Lake, High Level, Arcenciel Northeast weak 144 kv network Local large industrial loads -60 MVAR TCR, + 30 MVAR static filter +/- 100 MVAR SVC Little Smoky Northeast 240 kv grid area support -200 MVAR TCR, +100 MVAR static Filters

19 SVCs- South East +200/-100 MVAR SVC Hansman Lake, Lanfine Combination of TSC/TCR, allows more capacitive range Large motor loads in the area

20 STATCOMs 3 MMC STATCOMs, in service 2015 Provide HVDC Support Relatively weak southern grid requires extra reactive power support for HVDC converter stations Filter Switching Reactive Power consumption of inverter Voltage support to prevent commutation failure of HVDC

21 EATL Newel

22 HVDC EATL and WATL 1000 MW, 500 kv monopoles Connect generation in the north to load in the south

23 Thyristor Valves

24 Thyristor Valve Module

25 Converter Transformers

26 HVdc Wall Bushing, Smoothing Reactor

27 SVC Plus

28 Valve Hall and Control building

29 AC Yard Filter Banks

30 HVDC Tower Testing

31 McNeill Back to Back Connects Alberta to Sask 150 MW Back to back - no DC line, 40 kv, c Asynchronous grids Weakest network to have HVDC installed (ESCR=1.8)

32 McNeill Overview

33 Control of Power Electronics Modern microprocessor control devices Flexible, powerful, high speed Network Connected, complex, integrated

34 High Speed Control Flexibility to add compensating functions, speed up responses to specific events Eg: EATL DC Line Fault Recovery, SVC dispatch Easily port studies and design concepts to implementation Challenges with testing, complex software Debugging

35 EATL DC Line Fault Recovery Required SVCs to be positioned prior to recovery Implemented fault detection function and set SVC closed loop control to pre-arm SVCs for recovery All performed by Software within a few ms of the fault occurring

36 DC Line Fault Video DC Line Fault Test Video

37 Line Fault Recovery 90 ms < 0.05 pu SVC Assist

38 Complex Software = Complex Testing

39 Old - Analog Hard wired only limited, but simple Hard Wired indication Yard devices

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41 Modern Control Systems Challenges: Security, CIP Compliance Network integration issues Vendor inter-operability Future Development More seamless integration Plug and Play Better protocol definition Less proprietary software and protocols

42 Future FACTS in Alberta EATL and WATL Stage 2 Bipole 2000 MW VSC? Stage 3 Parallel Bipole 3000 MW Ultimate Multi-Terminal Multi- Terminal Stage 1 Stage 3 Stage 3 Stage 2

43 Future FACTS in Alberta Thickwood SVC +200/-100 MVAR SVC Fort McMurray area Possibility of STATCOM, TCR/TSC, or combination

44 Questions?