Route selection method suitable for arc suppression coil earthing electric network

Abstract

Disclosed is a line selection method which is applied to an arc suppression coil earth power system. Firstly, the zero sequence current of each feed line and the compensation current of the arc suppression coil can be sampled synchronously, and the zero sequence current of each feed line sampling value is added to the compensation current of the arc suppression coil sampling value point-to-point, and then a quarter of cycle (5mS) is moved forwards, furthermore, the signal is multiplied by the zero sequence current of corresponding feed line sampling value, and the algebraic mean value of a cycle can be obtained. Providing that only one value is negative and the others are positive numbers among the algebraic mean values, and the corresponding feed line with the negative value is the malfunction feed line; if all the algebraic mean values are positive numbers, the main line has malfunction. Because only the zero sequence current is used in line-selecting judgment and the zero sequence current is the zero sequence current of the feed line, the judgment is not affected by the angle error between the zero sequence voltage transformer and the zero sequence current transformer, and also is not affected by the dispersion characteristic of the zero sequence current transformer which has weak excitation (small current), and the line selection accuracy is high.

Description

technical field [0001] The invention relates to a small-current grounding line selection method for a power grid substation, which is especially suitable for a power grid whose neutral point is grounded through an arc suppression coil, including undercompensation, full compensation, overcompensation, and arc suppression coil parallel resistance or series resistance grounding power grid. The utility model belongs to the technical field of electric power automation. technical background [0002] Most of the 3~35kV medium voltage distribution network in my country adopts the small current grounding method. With the rapid development of the economy, the expansion of the scale of the power system, the increase of the length of the power system line and the increase and lengthening of the power cable line, the capacitance current of the power grid to the ground has increased significantly, and many power grids have exceeded the standards stipulated by the state. The neutral point...

AI Technical Summary

Problems solved by technology

When a single-phase ground fault occurs, the transient component of the ground capacitance may reach ten times or even dozens of times of the steady-state component, but the polarity establishment time that satisfies the first half-wave direction method of the transient current is very short; When the fault occurs at the zero-crossing point of the fault phase voltage or the excessive resistance of the fault point is large, the transient current is very small, and the method of the first half-wave direction of the transient current will fail at this time

Images