Line protection method

Abstract

The invention provides a line protection method. The method comprises steps that, (1), three phase currents and voltages IA, IB, IC, UA, UB and UC of a protection mounting line are acquired, positive / negative / zero sequence currents and positive / negative / zero sequence voltages are calculated and are Imu1, Imu2, Imu3, Umu1, Umu2 and Umu3 respectively, values of the mu are A, B and C respectively; Umu1COSphimu1 and a current asymmetry degree m are calculated, wherein m=(|Imu2|+|Imu0|) / |Imu1|, phimu1=arg(Umu1 / Imu1)+90DEG-phil, phil is a line impedance angle; (2), fault types are determined according to relations among p1, Umu1COSphimu1 and p2, the p1 is not smaller than -0.3 and is not greater than -0.1, the p2 is not smaller than 0.5 and is not greater than 0.6, various overloads are identified, the line under the overload situation can be protected through a blocking distance, under the fault situation, distance protection is opened, anti-transition resistance capability of line distance protection is greatly improved, the overload and fault identification algorithm does not require manual tuning and is realized through a device internally, the method is suitable for 220kV and higher voltage grade power transmission lines, a problem of distance protection overloading misoperation can be effectively solved, and accident scope enlargement is prevented.

Description

technical field [0001] The invention belongs to the field of relay protection, and in particular relates to a line protection method. Background technique [0002] In a large-scale blackout accident, the distance protection is affected by the overload and malfunctions to trip the non-faulty line, causing load transfer to cause cascading tripping of the non-faulty line, expanding the scope of the accident, and affecting the safe and stable operation of the power grid. [0003] At present, the setting value of load limit line in line protection needs to be set by the operator, but the setting value is set according to the possible maximum load during line operation, which affects the operation performance of distance protection and limits its ability to withstand transition resistance, that is, the line When a fault occurs through the transition resistance, the distance protection does not operate. However, the above-mentioned measures cannot prevent the distance protection f...

AI Technical Summary

Problems solved by technology

[0002] In a large-scale blackout accident, the distance protection is affected by the overload and malfunctions to trip the non-faulty line, causing the load transfer to cause cascading tripping of the non-faulty line, expanding the scope of the accident, and affecting the safe and stable operation of the power grid

[0003] At present, the setting value of load limit line in line protection needs to be set by the operator, but the setting value is set according to the possible maximum load during line operation, which affects the operation performance of distance protection and limits its ability to withstand transition resistance, that is, the line When a transition resistance fault occurs, the distance protection does not operate

However, the above measures cannot prevent the distance protection from malfunctioning during the accident overload

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