Researches On Risk Assessment And Preventive Control Of Static Voltage Stability Of Power System

The security operation of power system involves many factors, most of which we can't get their rules accurately, and these random factors result of various faults in power system directly or indirectly. In recent years, the security evaluation based on the risk of power system takes more attention. Different from previous analysis method, it considers the randomness and the severity of the damage of the fault in the system, which provides a more powerful guarantee for the safe and economic operation.The research of voltage stability is an important content of the security assessment of power system. As the power demand increases unceasingly, the state of power system is close to its limit, so the studies based on risk in voltage stability is very crucial. This paper analyzed the problems exist in static voltage stability comprehensively, and proposed the risk indexes and method of the analysis of static voltage stability combining with the theory of risk analysis method. Considering the limitations of the evaluation indexes in traditional static voltage stability, this paper used four indexes to evaluate the risk of power system which called static voltage instability probability, expectations cutting load index, load margin at risk and conditional load margin at risk. These indexes took the probability and consequences of the fault into account, and reflected the distance to the state of the instability point quantitatively. A calculating method was discussed on the basis of these indicators which combined of cutting load optimization model based on interior point algorithm, minimum eigenvalue analysis and continuous power flow analysis of static voltage stability. Considering the effects of the maximum output growth pattern of generators to load margin, the paper proposed a preventive control model which made the maximum load margin as the objective function to reduce the risk of the system after the risk of static voltage stability was acquired, realizing the optimal preventive control of the system. And a method to solve the model was investigated, too. Finally the research was summarized, and the further research work and research directions were pointed out.