docDynamic Fault Studies of an Offshore Four-Terminal
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Dynamic Fault Studies of an Offshore Four-Terminal
POEM 2013 Dynamic Fault Studies of an Offshore Four-Terminal VSC-HVDC Grid Utilizing Protection Means Through AC/DC Circuit Breakers Nicosia, 7-8 October 2013 Melios Hadjikypris (PhD) Prof. Vladimir Terzija Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 1 Contents 1. HVDC Fundamentals 2. Multi-terminal DC Networks 3. Simulation Studies: Four Terminal VSC-HVDC Network 4. Conclusions Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 2 1. High Voltage Direct Current High voltage direct current (HVDC) is a transmission technology based on high power electronic converters used in power networks for the bulk transmission of electrical power. • Transmission of large amounts of power over long distances (>600km) • Underground/Submarine cable connections (>30km) • Link between asynchronous AC grids Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 3 HVDC Configurations Monopolar Bipolar Homopolar Back-to-back (return path) Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 4 VSC-HVDC Technology VSC-HVDC is an innovative DC transmission technology utilizing Insulated Gate Bipolar Transistors (IGBT) in combination with Pulse Width Modulation (PWM) technique. Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 5 VSC Technology: Benefits • Independent control of active and reactive power • Faster power control due to increased valves switching (1-2kHz) • AC grid voltage control through reactive power support • No commutation failures • No need for a communication link between rectifier and inverter to coordinate their control action • Independent synchronous controllable voltage source feeding islands and passive networks • Multi-terminal DC (MTDC) networks application Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 6 2. Multi-terminal DC Networks By the year 2050 Europe will share its electrical energy needs through a giant MTDC network also known as the Supergrid. The technology used to support the power transfer operations will be based on VSC-HVDC technology. Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 7 DC Grids Configurations Constant voltage parallel scheme Converters are connected in parallel and operate at a common voltage. One converter establishes the DC voltage and the rest operate at constant current control mode. Constant current series scheme Converters are connected in series with a common DC current flowing through all converter terminals. One converter controls the DC current whereas the rest of them control the active power flows. In practice only the parallel scheme has been widely applied due to fewer line losses, better controllability and flexibility of future extension. Most suitable transmission technology for the parallel scheme is VSC-HVDC. Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 8 3. Simulation Studies: Four Terminal VSC-HVDC Network Q-Vdc AC1 AC1 Bus P-Q CB11 VSC1 10.95 MW CB12 VSC2 CB51 AC2 CB22 10 MW CB41 ne 5 CB24 P-Q AC2 Bus Line 2 Li Line 4 AC3 Bus Line 1 P-Q AC4 Bus CB43 AC3 VSC3 Line 3 CB33 10 MW CB54 VSC4 AC4 CB34 10 MW VAc=400kV (Line-Line) Vdc=320kV (Line-Ground) Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 9 Case Study 1: Permanent DC Fault CB11 VSC1 AC1 Line 1 VSC2 CB51 AC1 Bus CB12 AC2 CB22 CB41 AC2 Bus ne Line 2 Li Line 4 permanen t 5 CB24 AC3 Bus AC4 Bus CB43 Line 3 7.50 1.25 5.00 1.00 2.50 0.00 VSC1 VSC2 VSC3 VSC4 -2.50 -5.00 AC4 CB34 DC Voltage (p.u.) Active Power (MW) CB33 VSC4 DIgSILENT VSC3 AC3 CB54 0.75 0.50 VSC1 VSC2 VSC3 VSC4 0.25 0.00 Time (s) -7.50 1.0000 1.4000 1.8000 2.2000 2.6000 [s] 3.0000 Time (s) -0.25 1.0000 1.4000 1.8000 2.2000 2.6000 [s] 3.0000 MTDC Simulations Date: 11/02/2013 Annex: Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 /1 10 Case Study 1: Permanent AC Fault permanent CB11 VSC1 AC1 VSC2 CB51 AC1 Bus CB12 Line 1 AC2 CB22 AC2 Bus CB41 Line 2 Li ne Line 4 5 CB24 AC3 Bus AC4 Bus CB43 Line 3 CB33 VSC4 AC4 CB34 37.50 DIgSILENT VSC3 AC3 CB54 1.05 1.00 DC Voltage (p.u.) Active Power (MW) 25.00 12.50 0.00 -12.50 -25.00 VSC1 VSC2 VSC3 VSC4 -37.50 1.0000 1.4000 0.95 0.90 0.85 Time (s) 1.8000 2.2000 2.6000 [s] 3.0000 VSC1 VSC2 VSC3 VSC4 0.80 1.0000 1.4000 Time (s) 1.8000 2.2000 2.6000 [s] 3.0000 MTDC Simulations Date: 11/02/2013 Annex: /1 Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 11 Case Study 2: Transient AC Fault 200ms, 0+j0 ohms CB11 VSC1 AC1 VSC2 CB51 AC1 Bus CB12 Line 1 AC2 CB22 AC2 Bus CB41 Line 2 Li ne Line 4 5 CB24 AC3 Bus AC4 Bus CB43 Line 3 1.20 12.50 1.10 0.00 -12.50 -25.00 VSC1 VSC2 VSC3 VSC4 -37.50 1.0000 1.4000 1.00 0.90 0.80 Time (s) 1.8000 2.2000 2.6000 [s] 3.0000 AC4 CB34 25.00 DC Voltage (p.u.) Active Power (MW) CB33 VSC4 DIgSILENT VSC3 AC3 CB54 VSC1 VSC2 VSC3 VSC4 0.70 1.0000 1.4000 Time (s) 1.8000 2.2000 2.6000 [s] 3.0000 MTDC Simulations Date: 12/02/2013 Annex: /1 Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 12 Case Study 2: Transient DC Fault CB11 VSC1 AC1 Line 1 VSC2 CB51 AC1 Bus CB12 AC2 CB22 200ms, 0 ohms CB41 AC2 Bus Line 2 Li ne Line 4 5 CB24 AC3 Bus AC4 Bus CB43 Line 3 9.00 1.25 6.00 1.00 3.00 0.00 -3.00 VSC1 VSC2 VSC3 VSC4 -6.00 0.75 0.50 0.25 VSC1 VSC2 VSC3 VSC4 0.00 Time (s) -9.00 1.0000 AC4 CB34 DC Voltage (p.u.) Active Power (MW) CB33 VSC4 DIgSILENT VSC3 AC3 CB54 1.4000 1.8000 2.2000 2.6000 [s] 3.0000 Time (s) -0.25 1.0000 1.4000 1.8000 2.2000 2.6000 [s] 3.0000 MTDC Simulations Date: 12/02/2013 Annex: /1 Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 13 4. Conclusions • First attempt on exploring the dynamic behaviour of a VSC-MTDC network under AC/DC faults, i.e. experimentation of the degree of propagation of AC/DC disturbances on the DC/AC sides of the network respectively, and the effects these could have on its overall performance. • Additionally, this work tested the performance of DC-CBs integrated in a hybrid AC/DC network. The DC-CBs verified assistance in system’s protection and stability recovery. • Characteristic dynamics of system behaviour (AC/DC currents, voltages) under faulty conditions have been recorded which can further being used as a basis platform for the future development of a fault detection and location algorithm in VSC-MTDC networks. Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 14 Thank You Any questions? Melios Hadjikypris | The University of Manchester | POEM 2013| Nicosia October 2013 15
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