新疆750kV交流输电系统电磁暂态分析

Electromagnetic Transient Analysis on Xinjiang 750 kV AC Transmission System

结合新疆地区乌北—吐鲁番—哈密750 kV输变电工程,研究了线路各种运行情况下的潜供电流、恢复电压,验证了高抗中性点小电抗取值的合理性。对于同杆架设双回路段,计算了正常运行线路对另一回检修线路的感应电压和感应电流。研究了各种运行方式下的工频过电压以及合闸操作过电压,同时分析了合闸空载变压器的过电压和励磁涌流。最后计算了光纤复合架空地线(optical power ground wire,OPGW)采用分段绝缘单点接地方式时的感应电压。电磁暂态程序(EMTP)的仿真计算表明,潜供电流、恢复电压数值不大,高抗中性点小电抗取值合适。同杆双回路接地刀闸电气参数符合要求。线路两端装设高抗后,工频过电压符合我国关于超高压线路工频过电压的要求。线路三相合闸、单相重合闸操作过电压不高,而且对金属氧化物避雷器(MOA)热容量要求不高。合闸空载变压器过电压和励磁涌流较小。OPGW感应电压不大,数值和分段长度基本成正比,采用分段绝缘单点接地方式利于减小线路电能损耗。

It is necessary to study the electromagnetic transients of 750 kV transmission line so as to provide reasonable reference for Insulation Coordination.Combined with Xinjiang 750 kV transmission system,the secondary arc current and the recovery voltage were studied.For the double circuit transmission line,the induction voltage and current were calculated.Moreover,the power frequency over-voltage and switching over-voltage,as well as the inrush currents and the over-voltages of closing no-load transformer,were studied.The induction voltage of optical fiber composite overhead ground wire（OPGW） was calculated,which was sectionally insulated and unilaterally grounded.The theoretical analysis and simulated results of Electro Magnetic Transient Program（EMTP） show that the value of neutral reactance is selected suitably.The earth switch satisfied the requirements of withstanding the induction voltage and the induction current.The power frequency over-voltages are under the concerned regulations of our country owing to the reactors connected to the line.MOA is a good measure to limit switching over-voltage without high requirement on thermal capacity of MOA.The inrush current is low and will not threaten the transformer insulation.The induction voltage of the sectionally insulated OPGW will increase with the increasing of subsection length,and can obviously reduce the power loss.