Typical Hidden Failure Of Relay Protection Monitoring And Precaution

The role of the power system's protection schemes in the wide-area disturbances is critical. Incorrect operations of power system's protection schemes have contributed to a spread of the disturbances. This research defined hidden failures of protection schemes and showed that these kinds of failures have contributed in the degradation of 70-80 percent of the wide-area disturbances. It was found that hidden failures in protection schemes caused the disconnection of power system elements in an incorrect and undesirable manner contributing to the disturbance degradation.This paper introduces the problem of hidden failures in relay protection of power systems. Based on the concept and characteristics of hidden failures, the method to evaluate the hazard of hidden failures is put forward. The supervision and control of hidden failures will lower the occurrence of hidden failures, consequently the chances of the wide area system failures are reduced.The problem of power system security is described. The concept of vulnerability, main sources of power system vulnerability and vulnerability index are expounded in detail. This vulnerability usually causes catastrophic consequences in power system. With the measurement and current technology, how to prevent or decrease the power system vulnerability is expounded too.Based on analyzing all kinds of factors affecting distance protection in theory, this paper analyzes the effect of these factors concretely by simulation. Then a new-style adaptive distance protection principle is proposed. It improves the shortcoming of traditional relay protection. The multi-agent theory is applied in the adaptive distance protection, and the architecture of MAS is built in it. Through the cooperation among agents, the adaptive distance protection can adapt protection to various changes of power system automatically and intelligently. The problem of realizing adaptive distance protection can be solved by using agent. More useful information can be gained by using mobile agent. The cooperation between back-up protection and primary protection can be achieved. And also the hidden failures of power system can be supervised and controlled.