Wind farm collecting power line single-phase grounding fault distance measurement method

Abstract

The invention discloses a wind farm collecting power line single-phase grounding fault distance measurement method. The fault phase voltage, the phase current and the zero-sequence current at a wind farm collecting power line protection mounting place are measured as input values; based on an equipartition principle, the branch current after each fan fails is solved; based on the actual wiring topology of each fan on the collecting power line, a line description equation between the protection mounting place and a fault point is written out, measurement values are substituted into the equation sequentially, the initial value of a fault section is assumed, fault distances are searched and calculated step by step, and when the distance measurement result for the fault distance value obtained through calculation is just located in the assumed fault section, the searching is over, and the fault distance value at the time is the distance measurement result. The feature that the high voltage side of a fan box transformer adopts delta connection and thus, the zero-sequence current can not pass is made full use of, by only using the current measurement at the collecting power line exit, the current of each fan branch can be obtained approximately, a new measurement device does not need to be mounted, the cost is low, and the practical value is high.

Description

technical field [0001] The invention belongs to the field of fault detection and protection of power systems, and in particular relates to a single-phase grounding fault ranging method of a wind farm collector line. Background technique [0002] Wind power has become the third largest power source in my country. The rapid location and repair of faults in wind farms is of great significance to the safe operation of grid-connected power systems. However, wind farms are mainly distributed in the pass and canyon parallel to the main wind direction, plateaus and terraces, relatively prominent ridges and peaks, coasts and islands, such as windward and crosswind angles and other geographical locations with higher average wind speed, which are affected by factors such as the natural environment. impact, the failure probability of the collector line is high, especially when the fan branches on the collector line are connected to the T connection, multiple power sources will feed out ...

AI Technical Summary

Problems solved by technology

The traveling wave method realizes the fault location by measuring the time of the traveling wave head going back and forth between the observation point and the fault point, but the collector line has many wind power branches T-connected, resulting in many discontinuous points between the observation point and the fault point. Therefore, it is difficult to accurately identify the reflected wave head from the fault point, which makes the single-ended traveling wave method unable to be applied to the collector line

The impedance method describes the collector line equation between the observation point and the fault point, uses the outlet of the collector line to measure the voltage and current, and calculates the equivalent impedance between the observation point and the fault point, so as to realize fault location; the method applies When it comes to the wind farm power collection line, the main difficulty is that after the failure, the fan branches connected to the power collection line are all power supply branches, and they all inject fault current into the fault point, and the fault current of each branch cannot be measured, so that the direct The ranging accuracy of the impedance method is unreliable

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