Simulation and Experiment Analysis of 10 kV Flexible Grounding Device

The traditional 10 kV distribution network grounding system has some disadvantages, such as small grounding current and poor arc extinguishing effect, thus, hindering the detection of high-resistance grounding fault. Therefore, this paper studied the flexible grounding system consisting of small-resistance and active inverter in parallel. The control system comprises the compensation current calculation module, the fault detection module, and line protection strategy. During a single-phase grounding fault, the device is designed to inject a current of a given amplitude and phase into the neutral point to effectively suppress fault-point voltage and current and, meanwhile, quickly identifying the fault line or the busbar fault and then systematically protecting the distribution line. In addition, a large number of simulations have performed based on three grounding faults (metal, low-resistance, and high-resistance) and two modes (ungrounded and small-resistance grounding). The device can all be functional. Finally, a 400 V-level experimental prototype was built, and the experimental results are consistent with the simulation results, which can verify the effectiveness and feasibility of the flexible grounding device.