Unbalanced protection method and device for high-voltage serial connection compensation capacitor group

Abstract

The high-voltage series compensation capacitor group unbalance protection device is related to the relay protection of high-voltage transmission lines, and solves the problems of few functions and low sensitivity of the existing protection devices. Including the A/D conversion module, which converts the current generated by the capacitor bank current transformer D and the unbalanced current transformer E into digital quantities, and the data judgment and calculation module, which converts the current Ic of the capacitor bank, the unbalanced current ΔI, and the current of the capacitor bank A Threshold current Imk, capacitive reactance change rate Kx of the original H-arm capacitive reactance, reliability factor Kk to calculate the number of faulty capacitor units, storage module, storage threshold current Imk, capacitive reactance change rate Kx, reliability factor Kk, faulty The number of times and calculation results are used to protect the output module, and the judgment result of the calculation module is judged according to the data to alarm or trip protection.

Description

Technical field: [0001] The invention relates to a relay protection device and method of a high-voltage transmission line, in particular to the protection and protection method of a series capacitor compensation device in the transmission circuit. Background technique: [0002] At present, the 500kV AC transmission system is one of the main means to realize large-capacity long-distance power transmission in my country. The series capacitance compensation technology of transmission lines can effectively shorten the electrical distance between the head and the end of the transmission line. Therefore, the series capacitance compensation technology of transmission lines is an effective means to improve the transmission capacity of 500kV AC transmission lines. [0003] In the high-voltage power line, the series compensation device is used to perform series compensation on the power network. The compensation method is single-phase compensation, and each phase is a capacitor bank....

AI Technical Summary

Problems solved by technology

[0009] 1) The protection sensitivity is low, and the unbalanced current proportional coefficient setting value is relatively large in the unbalanced protection setting value, and its protection method cannot reflect a single capacitor fault

Generally, multiple capacitor units (more than 3) are faulty, and the faulty capacitor unit must develop in the direction of increasing unbalanced current before alarming, otherwise the unbalanced current cannot accurately reflect the fault degree of the capacitor

[0010] 2) Existing protection methods cannot reflect the symmetrical fault of successive capacitors

[0012] Therefore, unbalanced current protection cannot reflect the symmetrical faults of capacitor units occurring successively.

[0013] Since the high-voltage series compensation capacitors are generally inspected once a year, if there are multiple symmetrical faults in the capacitor bank and multiple symmetrical capacitor unit failures, the unbalanced current is still small, and the original protection cannot be judged; the operating personnel cannot judge whether There is a capacitor unit failure

This is extremely detrimental to the safe operation of the series capacitor bank

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