Reliability Evaluation Of Power System Based On Markov Theory

With the development of electricity markets, the stability of the power supply receives great attention. In order to ensure the safe and stable operation of the power system, power system reliability evaluation is becoming more and more important. Power system consists of generators, transformers, transmission lines, electricity consumers and other components. Therefore, through the analysis of the reliability of electric components and analysis of system reliability. Markov method has been adopted to effectively assess the reliability of electrical components and systems. This paper choose typical radial transmission lines and distribution systems as an example to illustrate.Transmission lines, whose main function was to transfer electric energy, was the core of power transmission system. Because of the long-term exposure in the field, widely distributed, electric transmission lines was affected by the sundry complex geographical environment, climate environment, and was interfered frequently by snow, lightning, wind, dust pollution, bird, fog, rain, external damage and other factors when it was running, which could cause the fault at any time, and even lead to blackout widespread. Distribution system is an important part in electrical system, lies in the end of the power system. As a part connected directly to users, the reliability of distribution system directly affects the normal power users. Therefore, it plays an important role in the safety, reliability and economy of power supply. According to various statistics show, the fault probably caused by power distribution systems, which account for 80% user outage. Therefore, it needs to create a simple and effective way to assess the reliability of transmission lines and distribution system.This paper proposes a mathematical model of reliability of the transmission lines and distribution based on theory of Markov. First of all, it should consider objects during operation may be in the State. Include intact condition, defects and fault State. The State of Markov models were established according to the transmission lines or distribution system. The transfer rate can be obtained by the average of the historical operation data and equivalence principle. Using state transition matrix and the current operating of transmission or distribution system, resolve to get transmission lines or distribution system running state changes the probability of future time and reliability index. Finally a case study of transmission lines and typical radial distribution systems, it illustrates the practicability of the method.