Research On Full Compensation Technology Of Ground Residual Current In Distribution Network Based On Controllable Reactor

With the increasing scale of the distribution network,the short circuit current increases sharply after the occurrence of single-phase ground fault in the distribution network.The existing arc suppression coil compensation has capacity bottleneck,and the increase of nonlinear load in the system and the use of a large number of power electronic components make the active component and harmonic component of the short circuit current increase,further restricting the ability of the traditional arc suppression line to compensate for the short circuit current,After compensation,large residual current can easily cause arc grounding overvoltage expansion faults,seriously endangering the safety of the power system.Therefore,it is necessary to conduct in-depth research on the full compensation technology for grounding residual current in distribution networks.This paper mainly studies the active full compensation technology for single-phase ground residual current in distribution networks based on controllable reactors,including the measurement of system to ground capacitance parameters,the study of full current compensation control algorithms,the study of fault recovery detection algorithms,the design and experimental analysis of full compensation systems.Firstly,the principles of three methods for measuring ground capacitance parameters of distribution network lines,the three frequency method,the frequency division method,and the frequency sweep method were analyzed.The measurement effects and applicability of these methods were compared through simulation,and the frequency sweep method was determined as the ground capacitance parameter detection algorithm used in the full compensation technology for ground residual current in this paper’s distribution network.Then,the control principles and implementation methods of two active arc suppression control algorithms,current method and voltage method,were studied.The residual current compensation accuracy and residual current control time of the two methods under different transition resistors and fault positions were compared and analyzed through simulation,their applicable transition resistance boundary values were obtained.Based on this,a current voltage combined compensation method was proposed to achieve full compensation control of grounding residual current within the full transition resistance range.Finally,a residual current compensation active exit method for real-time detection of ground fault recovery using active damping current injection was proposed.The theoretical analysis of the calculation basis for the active damping current value was conducted,and the effectiveness of the detection control method was verified through simulation.Based on the theoretical research of the full compensation technology mentioned above,this paper designs the software and hardware system of the fully compensated controllable reactor,and builds a hardware in the loop simulation platform based on the RT-LAB real-time simulation machine and controller.The proposed full compensation control strategy is tested through hardware in the loop simulation testing and 10 k V real type test field testing,and the results verify the feasibility of the residual current full compensation technology proposed in this paper.