Grounding faulty line selection in non-solidly grounded systems using transient energy

A new transient energy based principle for single-phase grounding fault protection in non-solidly grounded networks is proposed in the paper by analyzing the frequency response of zero sequence networks when the fault occurred. The transient energy function is defined as the integral of the derivative of transient zero-sequence voltage multiplying transient zero-sequence current. In the selected frequency band, whether the line is faulty or healthy is determined by the magnitude of the transient energy function, if it is less than zero, the line is faulty, else is healthy. The forming scheme and algorithm of the faulty line selection device is also presented in the paper. The demand for sampling frequency of the scheme is not very strict. Moreover, the direction comparison is between the derivative of transient zero-sequence voltage and transient zero-sequence current of the line, so it will require less analog quantity input path and does not need synchronous sampling.