A Hybrid Predictive Control Strategy for the Coordinated Voltage Control in Substation

The substation is one of the most important nodes for the power system voltage control. Its dynamic behavior is usually characterized by the interaction of dynamic load models, describing continues variables governed by differential equations, and of discrete controllers and coordinated logic, describing symbolic variables governed by discrete behaviors, logic rules and switching mechanisms. Therefore, the operation and control of the substation is a typical hybrid dynamic system. To make an effective voltage coordinated control in substation, this paper proposed a hybrid predictive control strategy. First, the discrete-time hybrid automata model was given for describing the hybrid voltage control system in substation. Then, by using the voltage-security control constrain instead of the goal of voltage-security control, the voltage coordinated control problem can be converted to a minimization cost problem on the premise of the voltage-security control, based on the technology of the MPC. And, for the discrete control characteristics and different control delays of multi-controllers, a branch and search algorithm was designed to solve the hybrid predictive control problem. This proposed algorithm is suitable for the voltage predictive control of substation, which have less control variables and different controllers' delays. Finally, the coordinated controller was designed on Dymola. And the example of BPA test system three generations and ten buses included was given for simulation analysis and the verification by the proposed approach for substation coordinated voltage control. The results of simulation showed that the proposed control strategy in the paper is feasible.