Study On Backup Protection Operational Risk Assessment Of The UHV Transmission Line

Relaying protection is an important part of the power system, whether it can correct operation directly influence the safe and stable operation of the power system. Along with the development of electric power system, the scale and structure of power grid become more complicated, along with the the constant change of power grid operation pattern one fault may cause protection device error act, which direct influencing safety and reliability of power supply of the power equipment. It will cause damage to the power grid stability and large-scale power supply blackout without effective control. Therefore, backup protection operation risk assessment of the UHV transmission line have very important meaning to provide basis for decision-making for the operation dispatchers.This paper expounds the necessity of establishing the model of backup protection operation risk assessment of the UHV transmission line, detailed analysis of the movement characteristics of starting element and phase selection components and distance protection components and zero-sequence current protection components of microcomputer protection. Combined with operation risk assessment method base on the principle failure, derived the operation failure probability calculation formula of start component and phase selection components and distance protection components and zero-sequence current protection components, and a computer program is developed. Establish the risk indexes of operation risk assessment, according to the Logic relationship with the microcomputer relay protection, evaluate the backup protection on CEPRI36v6system, verify the correctness of this method.The mothod of backup protection operation risk assessment of the UHV transmission line considering both the movement characteristics of the protection components and operating environment which has great influence on protection components, through the principle of protection derived failure probability of the protection components, then conducting risk assessment, which effective reflects the operation risk of relaying protection.