Power System Reliability Evaluation Considering Protection Miscoordination due to Topology Change

Document Type : Original Article


1 Department of Electrical and Computer Engineering, University of Birjand, Birjand, Iran

2 Department of Electrical Engineering, University of Zanjan, Zanjan, Iran


Protection system operation has a vital role in power system reliability. The protection system failure and incorrect operation may cause cascading outages. In case of fault, one of the effective causes of protection system mal-operation is the change in network topology. Network topology changes due to scheduled and unscheduled outages of power system components and dynamic changes in topology cause a change in the short circuit current of the network. The change in short circuit current affects protection relay operation and can lead to protection miscoordination which results in an outage of some loads and degradation of power system reliability indices. This paper proposes a novel Markov model including the miscoordination of the protection system due to component outages. In addition, a new index is proposed for protection miscoordination. A sequential Monte Carlo simulation approach is used to implement the proposed Markov model on a 24-bus IEEE reliability test system. The reliability indices, such as loss of load probability (LOLP), loss of load expectation (LOLE), expected frequency of load curtailment (EFLC), and expected energy not supplied (EENS), are obtained for four scenarios with different miscoordination levels and compared to show how the protection miscoordination degrades the reliability indices.


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