A Hybrid Flexible Arc Suppression System For Single-phase Ground Fault In Distribution Network

With the continuous expansion of the scale and capacity of the distribution network,the lines for residential electricity consumption are gradually increasing,the insulation of overhead lines and the cableization of urban roads,and the gradual increase of nonlinear loads.In a huge distribution network system,when a transient single-phase grounding fault occurs,the fault current contains large active components and harmonic components.Conventional arc suppression coils cannot fully compensate for this current component,so that the voltage and current at the fault are still large.The existing arc suppression method fails to compensate for the residual current of the fault,so that the fault arc cannot be extinguished,and then a large number of personal electric shocks and various fire accidents will occur,which will seriously threaten property and people.In this paper,a kind of voltage residual current compensation technology caused by ground fault is studied in depth,so as to improve the ability of the distribution network to restore the normal operation state.This paper expounds the advantages and disadvantages of the existing passive and active arc suppression methods,and analyzes the steady-state and transient characteristics of the neutral point ungrounded system and the resonant grounded system when a single-phase ground fault occurs.Arc technology provides a theoretical basis.Based on the existing voltage arc suppression technology,a hybrid flexible arc suppression method for single-phase-to-ground fault in distribution network is proposed.After a singlephase ground fault occurs in the distribution network system,the power source conversion module is used to clamp the neutral point voltage inversely to the power supply voltage of the faulty phase,and the amplitude and phase of the two offset voltages are accurately compensated by the active inverter.,so that the voltage at the fault point is much smaller than the arcing voltage,so as to achieve rapid arc suppression of single-phase grounding faults.The method not only has the characteristics of full compensation,but also has the characteristics of low cost and high reliability.Matlab/Simulink simulation tool is used to build a single-phase-to-ground fault simulation model of non-effectively grounded distribution network.First,the effectiveness of the pre-adjusted arc suppression coil used in the system is verified,and then the arc suppression effect and reliability when the system only has a power source conversion module are simulated.Since the fault point voltage is still very large when the high resistance is grounded,on this basis,a hybrid flexible arc suppression system with a power source conversion module and an active inverter is simulated and analyzed,and the system can be verified under different transition resistances.Arc ability and correctness.The results show that the flexible arc suppression system can completely compensate for the residual current and residual voltage at the grounding point,and at the same time greatly reduces the capacity of the active inverter.Using the real-type test site of the distribution network,the ability and correctness of the flexible arc suppression system composed of the power source conversion module and the active inverter for single-phase grounding faults are verified.The results show that the arc suppression system is reasonably designed,achieves the expected purpose,and can improve the reliability of the distribution network operation.