Studies On Fast Determination Of Practical Dynamic Security Region

Dynamic security problem of power system is becoming more and more important due to worldwide deregulation and interconnection of bulk power systems. Dynamic security region (DSR) is a more scientific and effective method for real-time security monitoring, assessment and control of power systems, compared with traditional"point-wise"approaches. In order to reduce the computation burden of determination of practical dynamic security region (PDSR), intercept method is proposed based on DSR theory, then a software is developed for dynamic equivalents of large scale power systems.Firstly, we propose intercept method for determining PDSR. In the basis of the intercepts of the hyper-plane with the decisive variables'maximum and minimum values, the ratios of the critical hyper-plane's coefficients are derived. The coefficients can be calculated based on these ratios and a critical operating point obtained by numerical simulation. In the same time, we analyzed association function of the method, which, according to the known PDSR corresponding to one fault, is used to quickly calculate PDSR corresponding to another fault. With the method's advantages of effectiveness and fast speed, a software for determination of PDSR is developed then applied in a practical Dynamic Security Regions Based Probabilistic Security Analysis System.In the basis of previous work, we develop a GUI software on UNIX platform for dynamic equivalents. It can be applied to reduce bulk system with 1000 generators, 10000 buses and 10000 transmission lines to a simple equivalent system so that the computation burden of determining PDSR is largely diminished. It is very simply to be operated due to creative design of the interface.Two practical means are adopted in the software. One is that multiple faults share one common equivalent system, which facilitates the data management. The other is to separated generators in each coherent group into several sets according to their initial angles and then ignore the admittance to ground generated in the aggregation process, so that we solve the problem that the calculation of power flow of equivalent system can't be calculated while maintain the precision.