A two-level system-wide automatic voltage control system

A two-level system-wide AVC system based on optimal reactive power flow (ORPF) is proposed. The architecture of this two-level system-wide AVC system is different from the popular three-level hierarchical structure in that it is implemented centralized. One distinguished feature of the described AVC system is that it does not require the need of performing zone division and it can automatically adapt to structural changes in power systems. Another feature of the described AVC system is that it works even when the state estimation function of the underlying control center fails. To achieve a close-loop automatic voltage control, the two-level system-wide AVC system has two optimization-based voltage control modules: an optimal reactive power flow module and a corrective voltage control (CVC) module. At present, the proposed AVC system has been commissioned and put into a close-loop mode in four provincial power grids in China. The performance of the two-level system-wide AVC system has been very encouraging.