Critical Protection Assessment Based On Risk Theory

Studies have shown that the occurrence of blackout is closely related to the incorrect operation of protection relay. Upgrading protection system is an important way to reduce the probability of blackout and enhance the reliability of interconnected power systems. How to upgrade protections and which protection devices need to be improved is an imperative problem to be solved. Therefore, an effective method to assess the critical protections is proposed in this thesis. Firstly, a protection action event tree is established under the incorrect action probability models and the action logic of protection; and then the index for measuring the importance of a protection is defined according to the contribution to the integrated system risk caused by the incorrect action of protection. The Monte Carlo method is used to simulate the operation process of protection. The importance sequence and critical protections are obtained by this method. It is prerequisite and basis for the rational and economical protection upgrading strategy. Finally, an effective solution is studied to enhance the reliability of protection systems. The simulation results on IEEE 39 bus test system illustrate the validity of this methodology.