Analysis of Voltage Control Strategies for Wind Farms

PCC voltage control is an important key to deal with upcoming challenges of large-scale wind power integration into electric grid. In this paper, based on the derived transfer functions of the plant and controllers, the dynamic performance of three voltage control strategies (centralized, decentralized, and distributed control) is evaluated in terms of robustness to variation of short-circuit ratio (SCR), disturbance rejection (DR), and impact of communication delay. After showing shortcomings of each strategy, an improved voltage control strategy with lower sensitivity to SCR variation and higher capability on grid voltage DR as well as on reactive current dispatch is proposed. The theoretical analysis is validated by simulation results in MATLAB. Finally, a small wind farm is modeled and simulated in RTDS to demonstrate the possible control interaction and reactive current sharing performance of the studied control schemes.