Analysis Of Power System Protection Modeling Based On PSASP Software

Relay protection is an important part of power system, its function is not confined to the rapid removal of the fault components only, it also plays a more important role in guaranteeing the safe and stable operation of the whole grid system.When we discuss the causes and process of the accident in power system, and analyze the stability problem of power system long dynamic process, the dynamic characteristics of protection is not allowed to ignore. So we can use power system dynamic simulation program to simulate the process of relay protection and analyze the whole process of power system stability based on the characteristics, which has important significance to avoid large area blackout accidents and study the effective measures to prevent them.First, the thorough review to the relay protection modeling is conducted to show imperfection of the present situation of power system simulation software., UD(user-defined) modules are used in the integrated power system analysis program (PSASP) to model power system transmission line protection according to different types of protection principle (including current protection, distance protection et al).The IEEE-39 and WEPRI-11 system are taken for simulation example to verify the effectiveness of the modeling method. Then, the causes and characteristics of hidden failures are analyzed. Aiming at three zone distance protection, several kinds of protection hidden failure mode of improper setting value of relay protection are analyzed in detail and simulation is carried on to show the effects of misoperation and nonoperation characteristics of protection to power system for subsequent optimization of fixed value. Finally, based on the Markov state space method, in view of two sets of main protection and backup protection of distance protection in high voltage transmission network, a detailed line-protection state transition model is presented to calculate the protection misoperation and nonoperation probability, thus an optimization method of setting value is given to achieve proper setting of protection, example is taken to verify the rationality of the method.