Abstract
Under single-line-to-ground (SLG) faults, the voltages and currents in resonant grounded systems will inevitably be distorted. To locate the faults quickly and accurately, this paper proposes a location method based on fault distortions. The faulty phase is firstly detected according to the first SLG fault feature below, and then the faulty feeder and section are detected according to the second feature below. 1) On the bus, one of the following distortions occurs. One dropped faulty-phase voltage (FPV) and two raised normal-phase voltages (NPVs). One dropped FPV and two NPVs (in which one rises and the other drops), where the product of FPV amplitude distortion and its phase-angle distortion is unique among three phase voltages. 2) On the faulty phase, the current on faulty feeder upstream rises, while the currents on faulty feeder downstream and normal feeders drop. Compared to existing methods, simulation tests show that the proposed method is robust under high impedance faults, and has a simple algorithm and easy engineering implementation. Also, it is effective under harmonics, three-phase imbalance, and different fault positions.
Highlights
SLG faults are the fault type with the highest incidence in distribution networks, accounting for more than 80% [1]
Chen et al.: Single-Line-to-Ground Fault Location in Resonant Grounded Systems Based on FDs
When a SLG fault occurs at the phase A on FFFFFFFFFFFF(nn) and the system enters into a steady state, it is equivalent to connecting a fault impedance ZZff in parallel with the phase A
Summary
SLG faults are the fault type with the highest incidence in distribution networks, accounting for more than 80% [1]. To ensure user safety and power supply reliability, the 6-66 kV distribution networks in China mainly use the resonant grounded system (RGS). If the system runs with the faults for a long time, it will threaten personal and equipment safety, and lead to more serious phase-to-phase short circuit faults. Many distribution departments in China still use the traditional “pull-feeder” method, which detects the faulty feeder by disconnecting feeders in turn and observing whether the fault indication signal disappears. This traditional method causes unnecessary power loss to users, and is not conducive to personal and equipment safety, and cannot further locate the faults. Chen et al.: Single-Line-to-Ground Fault Location in Resonant Grounded Systems Based on FDs
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