Distributed Voltage Control Based on ADMM for Large-Scale Wind Farm Cluster Connected to VSC-HVDC

A distributed voltage control (DVC) scheme based on the alternating direction method of multipliers (ADMM) is proposed for the large-scale wind farm cluster (WFC) connected to a voltage source converter-high voltage direct current system. The proposed scheme coordinates the reactive power output among several wind farms, and wind turbines (WTs) within each wind farm. This keeps the collector bus voltage of each wind farm and WT terminal voltages within the feasible range, and minimizes active power losses. First, a distributed reactive power control scheme based on the consensus ADMM is designed for the WFC, which can achieve fair reactive power sharing among wind farms with the optimal reactive power utilization ratio, to regulate the collector bus voltage close to the rated voltage. Second, a decentralized reactive power control scheme based on the standard ADMM is designed for each wind farm, which can effectively regulate reactive power outputs of all WTs within the wind farm. The ADMM algorithm is used to reduce the calculation burden of the wind farm controller. Moreover, the proposed decentralized control scheme coordinates the voltage regulation and economical operation. The DVC is able to effectively reduce the computation burden of the WFC and wind farm controllers, and the communication cost is reduced. A WFC with eight wind farms was used to validate the proposed DVC scheme.