Neutral non-effectively grounded systems and resonant grounded systems are widely adopted in power distribution networks in China, and the phase-to-earth fault happens most frequently in power distribution networks. Since the line voltage is still symmetrical under fault conditions, the systems can keep operating for one or two hours. However long-time earthing operation will result in two-point, more seriously, multipoint earthing fault as well as ground arcing fault caused over voltage. It will destroy the systematic safe operation. Thus how to detect the fault line quickly and accurately is an important issue in power system protective relaying, which has not been solved completely.
This article introduced in detail the neutral point earth system characteristic, does not construct the electrical power distribution system using MATLAB which 10kV the neutral point does not earth, carries on the breakdown simulation experiment, and has made the massive simulations to each kind of breakdown situation, has fully studied 10kV earth fault each kind of characteristic, therefore, the this article obtained conclusion to does not have the monitor and the trouble shooting with the neutral point earth system which the single-phase earth short-circuits has the important reference value.
Key words:Single-phase earth fault, neutral point earth system, breakdown, MATLAB simulation software