Study On Auto-Tuning Of Arc Suppression Coil And Ground Fault Detection For Non-Effective Grounded Power System

Single-phase to earth fault is the most frequently happened fault form in different kinds of power system . The probability is up to 70 percents in all forms of faults. Since no short-circuit loop is formed so that the fault current is small and the three phase line to line voltages are still symmetric when single-phase to earth fault occurs in a non-solidly earthed network, the load can be in normal operation for a period of time . But after the fault, the non-faulted phase voltage would increase and intermittent arc grounding would lead arc over voltage, therefore, the insulation would be damaged in long time running leading more serious phase-to-phase voltage. So single-phase to earth fault should be removed as soon as possible, In case of the fault can't be removed immediately, the fault line and fault path should be found automatically. The fault should be removed manually after the necessary load transferring.For the distributed capacitance of the network is the main cause of the fault current, it can be compensated and reduced by installing arc suppression coil(ASC). Especially when the ASC is auto-tuning, the capacitive current of the power system can be totally compensated by automatically regulating ASC's inductive current. Using the function of tracking compensation, the fault current could be reduced to a small active current and the arc can't maintain and will go out soon. Tracking compensation, which could remove the transient grounding fault automatically and greatly reduce the damage of the permanent grounding fault, is a kind of chief technical measures to reduce the loss caused by ground fault.The automatic fault line selection and fault location of single-phase to earth fault which could find the fault line and fault path quickly could be good for the reduction of the running time of system with fault and also be an important technical measure of reduction of the grounding damage.Given the previous research, this paper proposed a new approach oriented the auto-tuning of ASC and fault line selection and fault location of single-phase to earth fault and develop new automation equipment to resolve technical problems. The new approach is combined with modern analysis methods and new techniques according to the requirements of the distribution system. The details of the research work as follows:(1) Bring forward a new integrated design idea synthesizing three kinds of technology including auto-tuning of ASC, the fault line selection and fault location of single-phase to earth fault in non-solidly earthed network, which could not only simply the hardware architecture and wiring of equipment and also help the cooperation of different technical and functions to obtain optimum performance.(2) Put forward a calculation method of the value of the distributed capacitance to lay the foundation of the tracking compensation by collecting and calculating a signal of constant frequency injected to the power system through the secondary coil of the ASC. There's no necessary to have any operation of the ASC or regulation of the signal source. It has feature of easy to operate, high calculation accurate, fast response and having no any adverse impact to the system. In the above...