Test And Research On The System Of Relay Protection Of Power Transmission Line Fault

With the continuous expansion of network scale, the structure of the network is getting more and more complex, transmission lines of system is increasing, and the failure probability is more and more big, so the different types of short circuit fault is the most dangerous and common fault. Relay protection can be cut off the short circuit fault as soon as possible in, and reducing the damage of the equipment with maximum possibility. However, traditional power frequency variation in the longitudinal direction pilot protection is using full wave Fourier algorithm to calculate the fault state of the system under the process variable phase, and through different phases of the voltage and current phase can discriminate the fault direction, the action time of protection algorithm is more than a power cycle, while there is lacking of high speed and high sensitivity, the fault source cannot be removed promptly, it will cause a large number of casualties and economic loss.Point to this situation, come up with a positive sequence reactance speed directional protection method, it can solve the traditional power frequency variation in the longitudinal direction connection protection problem of lacking the rapidity and sensitivity. The research content is as follows:In the analysis of electric power system fault and positive sequence fault based on the superposition principle, the SRF: Synchronous reference frame, is a synchronous coordinate transform method, high speed calculation method is presented for a power system fault state of process variables are, in the fault system can be calculated protection device installation position of the fundamental positive sequence process variables phase in a very short time. Solving the problem of the traditional power frequency is sudden variable direction longitudinal joint protection.In view of the problem of traditional longitudinal joint protection with inadequate sensitivity, the method is based on process variable reactance of the directional protection. Through the process of variable reactance of the symbols can be in various practical condition reliably distinguish fault direction. Solving the problem of lacking of sensitivity of the traditional method.A lot of simulation experiments and theoretical analysis results show that the proposed high-speed algorithm can quickly and reliably judge the asymmetric fault direction, its performance is not affected by the fault resistance and system parameters, and can be better used in the high voltage transmission line protection.