| The rapid and high-quality economic growth has also ·t forward higher requirements for power supply.The neutral point grounding method of my country’s power distribution network mainly uses arc suppression coil grounding.Among them,single-phase grounding faults account for more than 80% of the fault types,and the residual current after the arc suppression coil compensation at this stage is still relatively large,which can no longer meet the needs of the power grid..Therefore,the active monitoring of single-phase grounding faults is very important to the safety of the power grid.This paper analyzes several important concepts in the normal operation state and singlephase ground fault state when the arc suppression coil is grounded.It is hoped to find the influencing factors of the current stage fault from the theoretical level,mainly involving the principle of voltage resonance of the power grid,The source and influence of voltage and residual current are balanced,and the formation and characteristics of arc faults in singlephase ground faults are analyzed.In order to improve the active detection ability of faults and make active compensation work with traditional arc suppression coils,accurate active compensation requires accurate measurement of the capacitance current of the system.The principle,advantages and disadvantages of the existing capacitance current measurement methods are analyzed in this article.An improved capacitive current measurement method with variable inductance and damping is proposed.The characteristics of the single-phase grounding permanent fault of the distribution network grounded by the arc suppression coil are analyzed,and it is found that the arc fault and the permanent fault have different fault current characteristics after active compensation.In order to quickly identify the single-phase grounding permanent fault,a Actively compensated single-phase grounding permanent fault identification method of distribution network.After several cycles of active active compensation for arc faults,the fault current shows arc current characteristics until finally disappear;while for permanent faults,the fault current only gradually decreases after active active compensation,and finally the fault current stabilizes at a smaller amplitude.Periodic change characteristics.This paper presents a method for judging the permanent single-phase grounding based on active compensation.Single-phase grounding faults are often accompanied by the generation of arcs.The harm caused by arc burning can damage the line insulation level and even cause disconnection faults.Therefore,if the arc always exists,it will cause great harm to the safe operation of the power grid.After analyzing two theories of AC arc extinguishing and reignition,combining the two theories believes that the extinguishing of arc faults needs to take arc extinguishing measures from the two stages of arc occurrence.An arc extinguishing method for distribution network based on active intervention is proposed.In the initial stage of an arc fault,for personal safety,the current at the fault point can be reduced through active compensation,and the current can be continuously injected to compensate for the capacitive current of the fault,so that the development of the arc is A relatively safe situation.Then with the development of the arc,the arc impedance becomes larger and larger.If you want to further reduce the fault current,the neutral point of the active device needs to withstand a very large voltage,which requires higher power electronic equipment,so it can pass the second stage of development.The intermittent power supply sets the voltage of the inverter so that the voltage at the fault point can be effectively reduced,so that the fault recovery voltage is always lower than the recovery speed of the medium,destroying the arc reignition condition,until the arc is automatically extinguished.An arc fault model was built on the simulation software PSCAD platform to verify the feasibility of this method. |
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