Researches And Design On Distance Relay Protection Of Transmission Line Based On RBFN

Good relay protection devices and reliable relay protection technology are important guarantee for safe operation of power system. The conventional relay protection technology can not satisfy the requirements of continuous developing power system. Therefore, the artificial neural network in the application region of relay protection has been researched recently, being a new hot researching topic.The conventional distance relay protection of transmission line is the main protection way in the high voltage transmission line network, for it is less affected by the structure of power system network and the operation mode. However, because of fault resistance, system oscillation and other factors, it will change the range of distance relay protection action, make the impedance relay disoperation, affect the performance of distance relay protection and threaten the safe operation of power system.The distance relay protection method of transmission line based on artificial neural network and digital signal processor (DSP) technology were studied in this paper by analyzing fault resistance and system oscillation carefully. Compared with back propagation (BP) network, radial basis function network (RBFN) model was chosen to study this distance relay protection of transmission line. The neural network model designed in this paper contains three sub-networks: identifying oscillations sub-network, fault detection and phase selection sub-network, and fault location sub-network. Integrated output of the sub-networks was used to identify the status of power system. The 500kV transmission line was simulated by using the alternative transients program (ATP). RBFN model was trained and detected using the simulated results which is handled. The detecting results show that this new type of distance relay protection mode of transmission line is able to identify various types of failures correctly, and it also can eliminate the impact of fault resistance and system oscillation.The hardware frame and part software to achieve the main functions of the protection system are designed in this paper. Taking TMS320F2812 DSP chip as the core, the device has the functions as follows: input signal processing, fault judging, sending control signal, data communication, real-time dynamic monitoring, failure alarm, etc.