May 4 Comparison of the Behaviour of Wind Farms and Conventional Power Dr. Martin Janßen APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT
Overview Introduction Grid Faults Requirements for Grid Stability Fault Clearance Measurement Characteristics of Generating Units Synchronous Generator Fully Fed Synchronous Generator Doubly Fed Induction Generator Simulation Simulation Model Simulation Results Conclusion 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be
Introduction The effect of wind power cannot be neglected anymore Grid operators expect wind farms to behave like conventional synchronous generators: Fault Ride Trough Voltage Control Frequency Control New Grid Connection Conditions How do wind farms behave during grid faults? Does this behaviour cause any problems? 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 3
Grid Faults Requirements for Grid Stability High short circuit current for triggering of circuit breakers Delivery of reactive current during the fault Fast recovery of active power after fault clearance 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 4
Grid Faults Fault Clearance A fault on a transmission line is connected to the grid by the two ends of the line The circuit breakers nearest to the fault open within 1 ms The circuit breakers at the other end open 4 ms after the first The individual phases of the circuit breakers open sequentially, typically 5 ms apart 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 5
Grid Faults Measurement Tree phase fault on a 75 kv transmission line Phase Voltage [kv] Fault Duration 33.5 kv (15.8 % of V nom ) 5 Phase A Phases B and C see similar voltage depressions to Phase A Phase B Phase C 8 ms 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 6
Characteristics of Generating Units Synchronous Generator High short circuit current Reactive current provided during grid faults Fast recovery of active power, but high oscillations Danger of tripping if fault lasts too long 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 7
Characteristics of Generating Units Fully Fed Synchronous Generator Variable speed generator Generator decoupled from grid, behaviour determined by the converter Low transients Limited short circuit current Reactive current provided by converter Fast recovery of active power possible Turbine High voltage High voltage Transformer ~ ~ SG 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 8
Characteristics of Generating Units Doubly Fed Induction Generator Most common variable speed wind turbine design High voltage dynamic leads to over current of the generator High short circuit current but low a.c. component Reactive power provided by generator and converter Fast recovery of active power possible Transformer DFIG High voltage High voltage ~ ~ 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 9
Simulation model Transformer HV - MV Transformer MV - LV ~ = Pro Wind = ~ Z G 11 % u k 6 % u k Generator u Grid ~ Z F u PCC u Gen M Turbine n Crowbar 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 1
Simulation 3-Phase Fault with U PCC = 15 % U N Synchronous Generator U Gen / U N U / U N U PCC / U N 1.5 6 4 i a, i r I Grid / I N - 4 - -4-1 1 3 4 t [s] 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 11
Simulation 3-Phase Fault with U PCC = 15 % U N Synchronous Generator U Gen / U N U / U N U PCC / U N 1.5 6 4 - -4-6 4 - -4 -.1.1..3.4 t [s] 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 1
Simulation 3-Phase Fault with U PCC = 15 % U N Fully Fed Synchronous Generator U Gen / U N U PCC / U N U / U N 1.5 1-1 - i a, i r I Grid / I N 1-1 1-1 -1 -.9 -.8 -.7 -.6 -.5 t [s] 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 13
Simulation 3-Phase Fault with U PCC = 15 % U N Doubly Fed Induction Generator U Gen / U N U PCC / U N U / U N 1.5 - i a, i r I Grid / I N - - -.1.1..3.4 t [s] 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 14
Simulation 3-Phase Fault with U PCC = 15 % U N DFIG + Fully Fed SG U Gen / U N U PCC / U N U / U N 1.5 - i a, i r I Grid / I N - - -.1.1..3.4 t [s] 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 15
Conclusion Wind farms can have a similar characteristic as conventional synchronous generators All types of generators have different advantages / drawbacks regarding short circuit current / reactive power / active power With an appropriate design and control wind farms can help to stabilize the grid 5.4 APCG / 4MJA5_Wind-Farms-IEEE_13-5-4_EN.PPT/ Dr.JANSSEN / Be 16
www.alstom.com