Study Of Neutral Grounding Modes In Medium Voltage Distribution Networks

In this dissertation, the different power system simulation models of different voltage levels are established, through using the power system toolbox of MATLAB simulation platform. Power line faults of medium voltage distribution networks of different voltage are done for digital simulation.The parameters of transmission lines are the resistance, the reactance, the susceptance and the conductance. The transmission line whose parameters are uniformly distributed is composed of the numerous small pieces. The transmission line equivalent model is described in detail.Three different neutral grounding modes of medium voltage distribution networks are introduced, which include insulated grounding mode, resistance grounding mode, arc-suppression coil grounding mode. When single-phase ground fault occurs, the fault is analyzed for state and transient according to the diagram of medium voltage distribution network of different neutral grounding modes and the zero-sequence equivalent circuit diagram.When single-phase to ground fault occurs waveforms and multiple data are generated, through MATLAB simulation and program. Application range of three grounding modes is known in 10kV and 20kV distribution networks, through comparison and analysis for waveforms and multiple data.Theoretical analysis and model simulation shows that for the medium voltage distribution networks, especially cable distribution networks, the arc-suppression coil grounding mode should be considered,when the capacitive current is 10A-150A. Between 100A～1000A, the low-resistance grounding mode should be considered. The three grounding modes have Advantages and disadvantages of themselves. Selecting the appropriate grounding mode should combine with specific conditions through comparison and analysis.