Impact of Drivetrain on Wind Farm VAR Control - Upwind

More documents

Recommendations

Info

UPWIND Table 4-12. Summary results <strong>of</strong> test cases for VAR control with brushless excitation <strong>of</strong> synchronous WTG implementing reactive power control Scenario Case SCR MVA base P WTG1 WTG1 (MW) (MW) Initial Q WTG1 (MVAR) Initial voltage WTG1 (pu) Load applied impedance (pu) Q final WTG1 (MVAR) Settling time (sec) 1 1 20 360 324 5.261 1.026 -0.5 -156.693 6 1 2 5 360 324 5.261 1.026 -2 -40.637 5.9 1 3 3 360 324 5.261 1.026 -3.5 -21.323 5.3 2 4 20 360 162 -3.743 1.017 -0.5 -155.807 999 2 5 5 360 162 -3.743 1.017 -2 -51.356 3.8 2 6 3 360 162 -3.743 1.017 -3.5 -31.284 3.7 3 7 20 180 162 8.851 1.029 -0.5 -78.288 999 3 8 5 180 162 8.85 1.029 -2 -38.3 6.5 3 9 3 180 162 8.851 1.029 -3.5 -18.576 6.3 4 10 3 360 324 5.261 1.026 -3.5 Settings <strong>of</strong> SCR 20 were -21.33 1.8 applied to SCR 3 4 11 5 360 324 5.261 1.026 -2 Settings <strong>of</strong> SCR 20 were -40.639 2 applied to SCR 5 4 12 20 360 324 5.261 1.026 -0.5 Settings <strong>of</strong> SCR 3 were -116.49 999 applied to SCR 20 5 13 20 360 162 41.945 1.043 -0.5 Higher initial WTG terminal -141.907 9.5 voltage *Settling time <strong>of</strong> 999 sec indicates inability to recover the POI voltage to the steady state value Deliverable D5.9.1 64 Notes
UPWIND 5. Summary Wind farms can be utilized to provide voltage control to the connected network using a supervisory VAR control. This work has presented the development <strong>of</strong> the VAR control for a large-scale wind farm to control the voltage at the point <strong>of</strong> interconnection (POI) with the electric grid. Different types <strong>of</strong> wind turbine generators (WTGs) have been considered to accommodate present and possible future drivetrain technologies. • The first type has power electronics interfaces with the electric grid. It includes the doubly fed induction generator (DFIG) machine type (GE 1.5/3.6 MW), which has a partially rated converter. It also includes the synchronous WTG machine (GE 2.5 MW), which is connected to the grid through a full converter. This type <strong>of</strong> power electronics interface with the grid features fast dynamic response <strong>of</strong> the WTG voltage. • The second type is the conventional synchronous machine type, which is directly connected to the grid. It has a longer excitation time constant and therefore, the WTG terminal voltage time response is slower. This type <strong>of</strong> machine can be implemented with future variable speed drivetrain technologies. For synchronous machine WTG types, two different excitation systems were investigated. The first one is the static excitation system and the second one is the brushless excitation system, which has a relatively slower time response. Two VAR control strategies were investigated. • The first strategy had only a WTG voltage control loop. The design does not take into account the machine reactive power capability, which can be exceeded particularly with higher SCR systems. It is worth mentioning that the control parameters should not make the VAR control response faster than that <strong>of</strong> the WTG excitation system to the extent that can cause voltage collapse with system disturbances, and in these cases the control parameters should be carefully chosen. This is important particularly with the brushless excitation system, which has a slower time response. • The second VAR control strategy included an additional reactive power control loop, which is vital to respect the machine reactive power capability. The VAR control design guidelines for each WTG type have been discussed. Test cases have been conducted to show the response <strong>of</strong> each WTG technology. A criterion for performance evaluation was developed. The main factors affecting the wind farm VAR control were investigated in detail with the following findings: • The grid short circuit ratio (SCR) level has a major impact on the control design and response. • Monitoring the number <strong>of</strong> connected WTGs is important for updating the control parameters. With over 50% <strong>of</strong> connected WTGs online, the impact is relatively insignificant. However with lower fraction <strong>of</strong> WTGs online, adapting the control scheme parameters is recommended for more robust control and for achieving roughly the same VAR control time response with different numbers <strong>of</strong> connected WTGs. • With well-tuned control parameters, the VAR control performance with the conventional synchronous machines could have similar time responses to that obtained with the DFIG machine type with power electronics grid interface or full power converter interfaces. Deliverable D5.9.1 65
Page 1 and 2:
Project UpWind Contract No.: 019945
Page 3 and 4:
UPWIND Contents Executive Summary .
Page 5 and 6:
UPWIND Figure 4-21. System response
Page 7 and 8:
UPWIND Glossary DFIG Doubly Fed Ind
Page 9 and 10:
UPWIND conventional synchronous mac
Page 11 and 12:
UPWIND dynamic model basis as in th
Page 13 and 14: UPWIND available wind power is less
Page 15 and 16: UPWIND Table 2-2. Wind farm system
Page 17 and 18: UPWIND 3. Wind Farm VAR Control for
Page 19 and 20: UPWIND 3.1.3 Wind Farm VAR Control
Page 21 and 22: UPWIND SCR:20 SCR:5 y-axis (min) y-
Page 23 and 24: UPWIND SCR:20 SCR:5 SCR:3 Figure 3-
Page 27 and 28: UPWIND +/- 10% of
Page 29 and 30: UPWIND Scenario Case SCR MVA base W
Page 31 and 32: UPWIND Table 4-1. Parameters <stron
Page 33 and 34: UPWIND Magnitude (dB) Phase (deg) 2
Page 37 and 38: UPWIND 20 3 0.2 1.65 3.3 5 3 0.49 0
Page 39 and 40: UPWIND 4.1.5 Results Summary and Co
Page 41 and 42: UPWIND Table 4-4. Summary results <
Page 43 and 44: UPWIND Given knowledge of</
Page 45 and 46: UPWIND reactance (Xgrid). The ratio
Page 49 and 50: UPWIND Table 4-7. Summary results <
Page 51 and 52: UPWIND Magnitude (dB) Phase (deg) 6
Page 55 and 56: UPWIND Vreg_ref + - K K i p ( 1+ s)
Page 57 and 58: UPWIND • Scenario 3: With half po
Page 59 and 60: UPWIND 4.2.4 Wind Farm VAR Control
Page 63: UPWIND 4.2.5 Test Cases and Results
show all

Impact of Drivetrain on Wind Farm VAR Control - Upwind

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?