Method for calculating integrated three-phase imbalance degree of multi-circuit transmission lines

Abstract

The invention provides a method for calculating the integrated three-phase imbalance degree of multi-circuit transmission lines on the same tower or in parallel. The method comprises the following steps: S1, finding out a three-phase imbalance degree r(i) of each single-circuit transmission line, wherein i represents a circuit number; S2, setting weight ci according to characteristics of each single-circuit transmission line; S3, setting a penalty function f[r(i)] according to the three-phase imbalance degree r(i) of each single-circuit transmission line and a critical value delta of the three-phase imbalance degree; and S4, calculating an integrated three-phase imbalance degree n of the multi-circuit transmission line, wherein n represents the sum of circuits of the multi-circuit transmission line. In the method, the weight is set according to the characteristics of each single-circuit transmission line, and the penalty function is set according to the three-phase imbalance degree of each single-circuit transmission line and the critical value of the three-phase imbalance degree, so that the calculated integrated three-phase imbalance degree can reflect the characteristics of phase sequence arrangement of the multi-circuit transmission line more exactly, thereby providing more reliable evaluation indicators for planning and designing the transmission line and for the optimal phase sequence selection of the transmission line in an operating stage.

Description

technical field [0001] The invention relates to a method for calculating the three-phase unbalance degree of a transmission line, in particular to a method for calculating the comprehensive three-phase unbalance degree of a multi-circuit transmission line on the same tower or a parallel transmission line with a short distance in the same transmission corridor. Background technique [0002] With the rapid development of power grid construction, transmission line corridors are becoming more and more dense, and multiple transmission lines or parallel transmission lines are erected on the same tower. The resulting complex alternating electromagnetic field environment may lead to serious three-phase lines between lines. Parameter imbalance problem. The unbalance of three-phase line parameters will cause three-phase current asymmetry. In severe cases, the current value of one-phase line is several times that of the other phase, which greatly reduces the transmission capacity of th...

AI Technical Summary

Problems solved by technology

The unbalanced parameters of the three-phase line will cause the asymmetry of the three-phase current. In severe cases, the current value of one phase line will be several times that of the other phase, which will greatly reduce the transmission capacity of the line, increase the loss of the line, and easily cause the zero-sequence current of the line to be too large. , resulting in zero-sequence protection action and line tripping

[0006] The traditional three-phase unbalance degree index is only for the three-phase power system of single-circuit transmission lines, but does not comprehensively consider the overall situation of three-phase unbalance of multi-circuit transmission lines

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