Three‐stage robust voltage/var optimal control of wind farms at multiple time scales

Abstract

In wind farms, the uncertainty of wind power and the incoordination of multiple time scales increase the difficulty of voltage/var control (VVC), and result in the reactive power output of VVC devices becoming unreasonable. This will decrease the power quality and even cause the voltage collapse of wind farms at large voltage deviations. For these problems, hierarchical control of VVC devices is a promising solution, as VVC devices can adjust the reactive power output in different control strategies. Therefore, this paper proposes a three-stage robust voltage/var optimal control strategy for wind farms. The robust optimization model is introduced to solve the VVC problem caused by the uncertainty of wind power in this strategy. Besides, compared with traditional VVC strategies, the proposed strategy can coordinate different control stages and VVC devices at multiple time scales by combining centralized and local VVC strategies, which achieves voltage/var optimal control objectives. Simulation results demonstrate the good performance of the proposed strategy in mitigating system voltage violation rate and power loss of the wind farm.