The Grid Avc Several Key Issues Discussed

Voltage is a very important index of electrical power system. Appropriate voltage level can ensure the security and stability of the system. At the same time, it is important to reduce the loss and improve the benefit of the system. Automatic Voltage Control (AVC) is an effective measure for improving voltage level and benefit. Its advantage is obvious, but its implementation is very complicated because of the nonlinear characteristic of voltage and reactive power. With the technology development of computer, communication and internet and the popularization of integration automation of power plant and substation, it is possible to implement AVC for power system. So AVC has been focused in research since 1980's. In this paper, on a macroscopical view, the implemental model of AVC is discussed according to the theory of decomposition and coordination and the project of AVC in Shandong power system. The design of AVC frame is proposed based on decomposition and coordination in space and time. In this AVC model, two concepts—general plant and substation, support capability of voltage and reactive power, are proposed; at the same time, the method of reactive power decomposing and coordinating optimization is suggested based on the subsystem of plant and substation and the main system of transmission net. A new hierarchical voltage control model which consists of tertiary voltage control, secondary voltage control and primary voltage control is conceived based on decomposition and coordination theory. This model is easy to cooperate with frequency control, expand AVC function, embed in EMS, and it also take in the advantages of AGC. The examples of reactive power decomposing and coordinating optimization of Shandong 500kV power system prove the effect and feasibility of this model.