A method of line protection

Abstract

The invention provides a line protection method, which includes the following steps: (1) collect and protect the three-phase current and voltage IA, IB, IC, and UA, UB, UC of the installed line, and calculate the positive sequence, negative sequence and zero The current and voltage of the sequence are Iμ1, Iμ2, Iμ0, and Uμ1, Uμ2, Uμ0, respectively, and the values ​​of μ are A, B, and C; calculate and current asymmetry m, where is the line impedance angle; (2) According to The relationship between p1 and p2 determines the fault type: Among them: ‑0.3≤p1≤‑0.1, 0.5≤p2≤0.6; identify various overloads, in the case of line overload, reliable blocking distance protection, in case of faults, Open distance protection greatly improves the transition resistance resistance of distance protection in line protection. The overload and fault identification algorithm does not need to be manually adjusted, and is realized inside the device; it is suitable for 220kV and above voltage level transmission lines, and can effectively solve the overload of distance protection. Misoperation, limiting the expansion of the scope of the accident.

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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