Adaptive secondary voltage control for grid interface of large scale wind park

Large scale, doubly-fed induction generator (DFIG) based wind power plants (WPP) are being designed to support grid voltage regulation. Based on the transmission level interconnection, this paper proposes a novel adaptive secondary voltage control (ASVC) strategy to improve network voltage profile and transient response performance. The control strategy combines algorithms for reactive current division, automatic gain controller and online voltage tracking scheme. The control strategy is tested in a system consisting of DFIG based Wind Park and conventional generation units, such as hydro and diesel synchronous generators, connected to a weak grid. Network voltage profile improvement achieved by ASVC is verified by simulation and compared with the conventional line-drop Secondary Voltage Control (SVC) and Primary Voltage Control (PVC). Since the system relies on the measurement and communication network, the time delay is modeled and considered. Improvement of the transient response of the controller is verified by simulation and comparison with a system without automatic gain control algorithm. Furthermore, the proposed control strategy is tested in both steady-state and under extreme system contingencies.