Research On The Operation Control Techniques In Arc-overvoltage Suppressor Grounded Power System

In distribution networks，70 percent of the faults are single-phase grounding faultsand most of them are transient arc grounding faults. In order to eliminate the arcover-voltage, the neutral point ground method with arc suppression coil is adopted.With the expansion of the distribution network scale, capacitive current has greatlyincreased. When the grounding fault occurs, the capacity of arc-suppression coil mustbe increased to compensate the grounding point current. The cost is significantly raised.However, arc-overvoltage suppressor costs less and is not affected by ground current.And complicate tracking and compensation calculation of capacitive current can beleave out. In particular, when the faults happen in transformer and high-voltage motor,arc-overvoltage suppressor is operated which will bring about short circuit of thetransformer internal windings.An operation control theory is proposed in the thesis to solve the applyingproblem of arc-overvoltage suppressor technology existing in low and medium voltagedistribution networks. By combining with the advantages for these two faultrecognition technology and adopting information fusion technology to compensate theweakness of the two different faults, the operation and control techniques is proposedbefore the action of arc-overvoltage suppressor. Considering about the effects ofasymmetric system, all kinds of disturbances and the probable wrong recognitionmaking the arc-overvoltage suppressor act, the sequence current in the whole systemshould be analyzed for different faults after the action of arc-overvoltage suppressor tomake sure whether the action is right or not. Then the arc-overvoltage suppressor canbe properly controlled. The damage accidence of the transformer will be avoided inarc-overvoltage suppressor grounded power system.The proposed novel arc-overvoltage suppressor operation control theory caneffectively identify single-phase grounding faults, transformer internal faults and loadtransformer internal faults. The arc over-voltage suppressor and transformer protectionare controlled to work. Transformer burning resulting from wrong operation of arcover-voltage suppressor is avoided. It is verified by MATLAB and EMTP simulation.