Line-break Fault Detection And Location Of10kV Distribution Line

With the improvement of the distribution automation level and electricity demand growth, there is a growing emphasis on power quality and power supply reliability. lOkV distribution line runs on complex environment and is prone to line-break fault. There are many reasons to produce line-break fault. Line-break fault has a great impact on the grid, which can directly affect the safe and stable operation of the grid and even endanger the personal safety. So people should need to pay more attention to line selection and localization research of the line-break fault.In this paper, symmetrical component method and compound sequence network are used to analyze the electrical quantities of a single-phase line-break fault. Negative sequence current after single-phase line-break fault has a bigger mutation than the normal line, and basically an opposite direction to negative-sequence current of the other non-fault line. So it can be used as the fault line selection criterion condition. The characteristic of the positive sequence current change is also evident. The fault phase current reduces to zero, the other non-fault phase currents drop to equal size and opposite direction, which can distinguish line-break fault from TA break fault. The phase voltage changes on the both sides of fault location are different,so the zero-sequence voltages are. Similarly current and voltage variation summary are summarized on the branch line single-phase line-break fault.The wire landing on the both sides of fault location can form a line-break with ground complex fault. This paper analyzes single-phase line-break fault with power side ground and single-phase line-break fault with load side ground. The single-phase line-break fault with ground has the same current variation with the single-phase line-break fault. The phase voltage changes on the both sides of fault location are different,so the zero-sequence voltages are. This paper makes a theory analysis on the electrical quantities variation of multiphase phase line-break fault or multiphase phase line-break with ground fault which may occur, the three-phase currents are all zero, and there is no sequence current, the phase voltages and zero-sequence voltages on the both sides of the fault location also have their own characteristics.Negative sequence current and positive sequence change current are proposed as single-phase line-break fault and break with ground protection criterion based on the previous theoretical analysis.Negative sequence current and positive sequence current change may appear on asymmetric short-circuit and TA break fault, so phase current change amount is proposed as an auxiliary criterion, which can be used to detect the single-phase line-break fault and avoid protection misoperation on asymmetric short-circuit and TA break. Two judgment methods are raised on B phase with TA or not. Positive sequence current changes are proposed as multiphase line-break fault protection criterion, phase current values after fault are used as an auxiliary criterion to detect the multiphase line-break fault.Segmented to get the voltage is used to observe whether the phase voltages change trend are same on two neighboring nodes, if yes, then it is the fault area between two neighboring nodes. TV open delta voltages value on two neighboring nodes are also used to locate the fault area, the fault type can be judged with the phase voltages and TV open delta voltages of power side.10kV distribution line simulation model is structured to simulate various fault types and analyze the variation of the voltage and current by PSCAD/EMTDC and MATLAB software. It need to calculate the phase and zero sequence voltages of two sides, phase currents and the sequence currents, which can prove the voltage and current theory analyses are correct, and the negative sequence currents and positive sequence currents as protection criterion have a higher sensitivity, using the amount of change of phase currents as auxiliary criterion also has a high accuracy and using the voltages of two sides to locate fault area and judge fault type is feasible.