Comparison of load margin analysis for steady state voltage stability

Voltage stability becomes an increasing severe problem as the power systems become more complex and heavily loaded. Voltage problems have been a subject of great concern during planning and operation of power systems due to the significant number of serious failures believed to have been caused by this phenomenon. Therefore, how to develop an efficient research technique is one of the issues which the researchers most care about. For steady state voltage stability assessment, there are kinds of powerful methods can be used, which are continuation power flow (CPF), interior point method (IP method), sensitivity analysis and so on. However, the CPF and IP methods are based on margin analysis. Margin analysis for voltage stability is an efficient approach to evaluate steady state voltage stability, which can indicate the distance between operating point and collapse point of power system. There are two main ways to deal with margin evaluation problems of voltage stability: CPF method and primal-dual interior point method (PDIP method). In this paper, both an IEEE 118-bus system and a real power grid in China are analyzed in order to compare CPF method with PDIPM to find out the differences between the two methods. The contrastive result of algorithm on accuracy, reliability and flexibility shows that the CPF method is more preponderant than the PDIP method. Moreover, the CPF proposed in this paper considers the opening operation of transmission line, which promises that the result makes sense.