Transmission Network Reliability Evaluation Considering Protection Failures

The reliability evaluation of the relay protection and large-scale power networks are two hot topics of current research on power system reliability. In view of the existing problems related to the current research, the failure rate estimation of relay protection and transmission network reliability evaluation considering protection failures were studied in this paper and some results are obtained. The main research contents and achievements of this paper are as follows:A novel evaluation method combining statics and state score was presented to calculate the failure rate of the protection. The method of calculating protection components statics failure rate was first proposed based on alarm information; secondly, by building the scoring model and modeling the map between state score and failure rate, the components' failure rate of operation is calculated on the basis of the status messages. Finally, the failure rate of each component was obtained by weighting both the failure of first class and second class, and then the integrated failure rate of system was gained through weighting all the failure of components. The calculation results of alarm information and operation state information of relay protection operation in a provincial power system show that, the method proposed is accurate and valid.Based on the analysis of line outage under the two types of protection failures, the failure of circuit breaker and cooperation of protection system in between, a new reliability analysis approach on transmission system is presented based on the complete Markov model of line states and sequential Monte-Carlo simulation. A complete Markov model is established first for transmission lines considering failures of protection and circuit breaker. Then simulation of system states resulted from primary equipment and secondary equipment are carried out by sequential Monte Carlo method and reliability indexes are calculated, thus realizing the reliability analysis of a whole power system.A novel identification method for critical protection was proposed based on reliability and risk assessment. Important index of protection operation were first created based on risk evaluation method, achieving failure risk and importance of each protection. Then Monte Carlo method was introduced to analysis the aftereffects of protection failure. Eventually, importance index of each protection was calculated based on failure probability computation through protection reliability analysis.