特高压交流变电设备相间操作冲击的放电特性

Phase-phase Switching Impulse Discharge Characteristic of UHV AC Substation Equipment

为取得特高压交流输变电工程的设计依据,结合晋东南—荆门百万伏级交流输变电示范工程,研究了交流变电设备的相间操作冲击电压特性。用电压分别为5400、3000kV的冲击电压发生器联合进行相间试验,通过适当调整时延实现相间试验时2台冲击同步;采用升降法获得5～9m距离的环、管型母线、4分裂导线相间操作冲击电压放电特性曲线;通过计算得到其相间操作冲击的间隙系数k,并分析电压分配系数α对相间50%操作冲击击穿电压U50的影响。试验表明,U50随着α增大而增加,且通过长间隙放电理论中临界电荷法解释相间绝缘的U50随着α增大而增加的原因,试验结果与IEC等国外类似试验相接近,证明本次试验的可比性和可靠性。

In accordance with the project of UHV AC transmission and substation to be constructed , this paper researches the switching impulse discharge characteristic curve of 1 000 kV AC substation equipment air gap, based on the 1 000 kV AC power transmission ＆ transformation project from the southeast in Shanxi province to Jingmen of Hubei province. Two sets of impulse voltage generators are used to experiment conjointly, whose voltages are respective 5 400 kV and 3 000 kV. By adjusting the time delay unit to make the two impulse generators in synchronism. The test uses up and down method to obtain the discharge characteristic curve under switching impulse between the ring phases, the tubular bus phases and the 4 multiple conductor phases which have 5 - 9 m distance. Then base on IEC standard, gap coefficient k of phase to phase is get. At the same time, the influences of coefficient of voltage distribute and the wire layout to 50% switching impulse discharge voltage U50 of phase to phase insulation are tested and analyzed. Discharge voltage U50 rise along with the rise of coefficient of voltage distribute. Based on discharge theory of air gap, the method of critical charge is applied for explaining the relationship between coefficient of voltage distribute a and discharge voltage U50 of phase to phase. The test results are closed to those of the similar experiments of IEC and others, which showed the reliability and comparability of this test.