基于时域解析法的电容式电压互感器铁磁谐振分析与抑制

Analysis and Suppression of Ferroresonance of Capacitive Voltage Transformer Based on Time Domain Analytical Method

高压、特高压输电线路多采用电容式电压互感器(capacitance voltage transformer,CVT)进行电压变换,随着运行年限增长后运行参数发生变化,线路投切短时极易引起CVT参与的铁磁振荡事故发生。针对该问题,基于一起CVT分频铁磁谐振的实例,简述了振荡过程,建立CVT并网参与铁磁谐振的振荡理论模型,采用中间变压器励磁特性分段线性化等效方法,实现CVT内部铁磁谐振的分段线性时域解析分析,结合仿真及原件参数实地测量的方式找到CVT铁磁谐振发生原因,并提出相关抑制措施,为CVT的运维检修提供了依据。

The high voltage and ultra-high voltage transmission lines mostly use capacitive voltage transformer(CVT)for voltage conversion.With the growth of operation years,the operation parameters change and the short-time line switching is very easy to cause the ferromagnetic oscillation accident participated by the CVT.To solve this problem,based on an example of frequency division ferroresonance of the CVT,this paper briefly describes the oscillation process and establishes the oscillation theoretical model of CVT grid-connection participating in ferroresonance.It also adopts the piecewise linearization equivalent method of excitation characteristics of intermediate transformer,realizes the piecewise linear time domain analytical analysis of ferroresonance in CVT,and finds the cause of CVT ferroresonance by means of simulation and field measurement of original parameters.Finally,it proposes relevant suppression measures,which provides a basis for operation and maintenance of the CVT.