Cooperative Voltage Control For Multi-area Power Systems Based On Dynamic Game Theory

With the rapid development of large-scale interconnected power network,the coupling among regional power grids is getting stronger and stronger. The voltage level of the adjacent areas will be affected, while a certain area tries to stabilize its voltage level through various voltage control means. The voltage controls of each area must be coordinated, in order to obtain a better control performance. This paper focuses on the coordination problem of voltage controls among multi-area power systems to do the research work as follow.Firstly, this paper introduces some basic concepts of voltage stability and voltage control of power system, as well as summarizes the domestic and foreign research of coordinated voltage control in current. After determining the long-term voltage stability as the research object, a detailed mathematical model of the power system under the framework of long-term voltage stability is established in this paper.Secondly, the phenomenon of multi-area voltage control is analyzed, and then the dynamic game theory is introduced into voltage control. Thus a multi-area cooperative voltage control method is proposed in this paper. Based on the existing optimal coordinated voltage control model, the dynamic game model of multi-area cooperative voltage control is established in the form of non-zero sum, non-cooperative, non-linear and quadratic. The proposed voltage control method can achieve two levels of coordination: on the one hand, it can coordinate the actions among the different voltage controllers inside the region, on the other hand, it can also coordinate the voltage control among different areas.Thirdly, the algorithm of solving the multi-area cooperative voltage control is explored. On the foundation of comprehensive analysis of the mathematical characteristics of the model and the characteristics of the multi-area power systems, the multi-area cooperative voltage control model is transformed into a simpler model which is easier to solve, after a series of transformation. Combining the distributed algorithm and the optimization algorithm, a twolayer iterative algorithm based on Ward equivalent and the primal dual interior point method is proposed for solving the problem. Then a detailed introduction of the algorithm principle and the calculation steps is also given in this paper.Finally, New England 10-machine 39-bus system and a 78-bus system, which is constituted by two 39-bus systems, are chosen for case study. The Nash equilibrium strategy of multi-area cooperative voltage control is obtain through the proposed two- layer iterative algorithm. Three voltage control methods are compared in this paper, which are the optimal coordinated voltage control of single area, the optimal coordinated voltage control of the whole system, and the cooperative voltage control of multi areas. The simulation results show that the multi-area cooperative voltage control based on dynamic game theory can effectively improve the long-term voltage stability of power system, with its own advantages compared with the other two control methods. The control strategy can coordinate the voltage control of all areas, and is has also powerful persuasion for each area, so that all areas will execute the control strategy faithfully, verified the effectiveness and superiority of the proposed voltage control method.