A new integration method of fault line detection in resonant earthed system based on instantaneous real power and instantaneous virtual power

The accident transition information is not only complex but also enrichment when single-phase-to-ground fault occurs in resonant earthed system. A new integration method of fault line detection based on instantaneous real power and instantaneous virtual power is proposed in this paper. Not as health lines, when single-phase-to-ground fault occurs in resonant earthed system, the grounded current of faulty line contains distinct transition damping oscillation direct current component with the compensation of arc suppressing. The damping oscillation direct current component shows the characteristics obviously of damping oscillation of industrial frequency through the analyses of instantaneous real power and instantaneous virtual power. Here, the characteristic frequency of 50 Hz in instantaneous power theory is defined. By calculating the instantaneous real power and instantaneous virtual power respectively of each line after single-phase-to-ground fault occurred, the oscillator components can be decomposed. Through comprehensively analyzing the value of oscillator components with the characteristic frequency of instantaneous real power and instantaneous virtual power, the integration algorithm of fault line detection can be established. The new method makes full use of transition information without considering phase position and multiple distinguish. Large amount of simulation results shows that the proposed method is accurate and reliable.