Research On Compensation Of Active Component To The Single-phase Ground Fault Residual Current In Resonant Grounding System

Resonant grounding system is neutral point ground system that is used widely tothe medium and low voltage distribution network in China.It is able to improve powerquality and grid operation safety and reliability.In current, one central issue ofresearch in resonant grounding system is how to further reduce the ground residualcurrent of system in order to ensure ground Arc not rekindle.In previous studies ofresonant grounding system, the arc suppression coil loop was able to be used tocompensate capacitive reactive component of the ground current when single-phaseground fault occurs and not able to compensate active component of the groundcurrent.With the expansion of the distribution network, the extensive use of powerelectronic devices and nonlinear loads increasing, the active component of the groundcurrent will increase substantially.However, the increasing of active componentcurrent is not conducive to extinguish ground arc, if the large active componentcurrent is probable to cause arc to and system will emerge overvoltage and otheraccidents.Simultaneously,we discovery the ground residual current has a greatrelationship with the ground resistance and the changing of damping rate to thesystem also influences neutral point displacement voltage, the ground residual currentand fault recovery phase voltage.The paper uses the active inverter technology andcalculates command current of prediction to be used as the reference signal to controlinverter, in oder to achieve compensation to active component of the ground residualcurrent.Simultaneously, we also analysis and research the influence of system causedby the change of the damping rate.Firstly, the paper introduces and deduces the basic theory of resonant groundingsystem,analyses neutral point displacement voltage, the ground residual current andfault recovery phase voltage of the system caused by the damping ratechange,describes the source of the active component to ground current in brief,contrast the measurement method about active component to ground current andpresents measurement method in this paper-the neutral point displacement voltagemethod. Then direct how to achieve compensation to the active component of theground residual current to conduct derivation and research. Simultaneously, contrastsand describes the most widely used current tracking control method in thecurrent(Including hysteresis control, triangle wave comparison, fixed switchingfrequency).By building the relevant model in Matlab/simulink, the simulation, verify the correctness of the theory of the previous and also while active currentcompensation conducts analysis and research of Flexible control about arcsuppression coil loop. Finally, analyses and describes element needed for experimentplatform, designs hardware and software for the control circuit, and use the result ofexperiment certificates the impact of the system caused by the change of damping.