The Analysis and Application of Practical Criterion for Single-Phase-Ground Fault in Ungrounded Power System

In ungrounded power system, single-phase-ground fault is the frequent fault, and has much influence on the safety and stability of power system. This paper analyzes the fault system, and generalizes the determining methods of fault phase and fault line. On this basis, DSP (digital signal processor) intelligent protection device is built. The DSP device can search for fault phase and line rapidly and accurately according to the system structure and operating characteristics. It is shown that the reliability of the power supply can be ensured and integrated automation level of substation improved.