Contrable metal oxide arrester in use for transmission system in supervoltage, extra high voltage

Abstract

The controllable arrester in metal oxide includes control part and fixed part connected in series. In normal operation of system, the control part and the fixed part together bear system voltage. When amplitude value of system over voltage exceeds prearranged threshold value, the fixed part bears system over voltage. Combining power electronic device in large power with arrester in metal oxide (MO), the invention puts forward concept and designing idea of controllable arrester for aiming at issue of over voltage protection for transmission system in super voltage, extra high voltage. Based on condition of maintaining invariable performance parameters of MO resistance piece, the invention reduces residual voltage of arrester effectively by using characteristics: quick response speed of power electronic device, steady operation, and flexible adjustment so as to raise protection level for arrester.

Description

Technical field [0001] The invention relates to an overvoltage protection device for an ultra-high voltage power transmission system, and more specifically, to a controllable metal oxide arrester for an ultra-high voltage power transmission system. Background technique [0002] Starting from the ultra-high voltage (330kV~750kV) transmission system, the operating overvoltage has already played a control role in the insulation level of the power transmission and transformation equipment. As the system voltage level increases, the impact becomes greater and greater, and the operating overvoltage must be multiplied The limit is getting lower and lower. In the UHV (1000kV) power transmission system, the operating impulse discharge voltage of the air gap presents saturation characteristics, and the operating overvoltage level has a greater impact on the cost and manufacturing difficulty of power transmission and transformation equipment. Therefore, the operating overvoltage multiples s...

AI Technical Summary

Problems solved by technology

[0007] However, these two measures still have major deficiencies in terms of operational reliability and economy:

[0008] (1) In the UHV transmission system, the residual voltage of the arrester is required to be low. According to the performance of the existing resistor, it can only be realized by increasing its operating charge rate; in addition, the height of the arrester is large, and the influence of stray capacitance on the ground makes the resistor The unevenness of voltage distribution increases, and the charging rate of some resistors increases further

These two factors cause the aging speed of the arrester resistor sheet to accelerate under normal operation, and reduce the reliability margin of the arrester compared with the EHV system

[0009] (2) After the circuit breaker is equipped with a closing resistor, the mechanism is complicated. A large number of operating experience of the ultra-high voltage system shows that in the circuit breaker damage accident, the breaking of the closing resistor and the failure of the operating mechanism are the main reasons. The power system caused by the damage of the circuit breaker Accidents are dangerous

Since the 1980s, researchers at home and abroad have discussed and studied the situation of the series and parallel discharge gaps of metal oxide arresters, but it is difficult to solve the dispersion of the gap discharge voltage, and the reliability of the arrester is poor.

During the 1990s, researchers in the United States conducted theoretical research and simulation calculations on surge arrester shunt thyristor devices in order to suppress the operating overvoltage requirements caused by reactive power compensation capacitor switching, but no actual products came out.

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