High speed digital distance protection-real time simulation and hardware development

The authors present the development of a high speed digital distance protection scheme based on the finite Fourier transform algorithm. Techniques on cutting down on-line calculation are introduced. Real-time simulation shows that all the relay processing functions can be completed within one sample interval based on a 4 kHz sampling rate. A multi-processor hardware scheme is developed. Test results show that the protective relay possesses very fast operation with high sensitivity and selectivity