Online Supervisory Voltage Control for Grid Interface of Utility-Level PV Plants

Large-scale photovoltaic (PV) plants are being designed to support grid-voltage regulation. Based on transmission-level interconnection, this paper proposes a novel online supervisory voltage control (OSVC) strategy to improve network voltage profiles. The system structure includes the algorithms for reactive power allocation and online voltage tracking. The effectiveness of the proposed OSVC that improves the network voltage profile is verified by simulation in comparison with the conventional line-drop secondary voltage control and primary voltage control. Since the application relies on the measurement and communication network, the time delay is considered. Based on the available bandwidth of the wide-area measurement systems (WAMSs), the simulation shows the feasibility and success of utilizing the OSVC for real-world implementations. The study also indicates the transient response can be improved further by the proposed solution when high-bandwidth WAMS infrastructures are available in the future. Furthermore, the proposed control strategy is tested in a weak power network with the low-short circuit ratio and failure of communication.