励磁涌流引起换流变瓦斯继电器误动的振动及油流特性研究

Study on vibration and oil flow characteristics of gas relay in converter transformer caused by inrush current

在实际直流输电工程中,换流变压器在空载合闸时产生的励磁涌流导致其瓦斯继电器误动的事故频发,由于对励磁涌流下换流变压器振动及其油流特性的研究不足、故障机理不明确,瓦斯继电器误动等事故时有发生。为此,本文以某实际换流站中换流变压器网侧绕组空载合闸为例,搭建换流变压器励磁涌流电磁暂态模型,分析不同剩磁及合闸角下的换流变压器励磁涌流波形;搭建换流变压器电磁-力-流耦合的有限元模型,研究涌流作用下换流变压器的振动特性,箱体及油管内油流压强及流速特性。研究成果可为换流变压器瓦斯继电器在励磁涌流下的误动故障机理的分析提供有效参考。

In actual DC transmission projects,gas relay misoperation accidents occur frequently because of the inrush current generated by converter transformer during no-load closing.Due to insufficient research on the vibration and oil flow characteristics of converter transformer with inrush current and unclear fault mechanism,it is difficult to restrain the misoperation accidents of gas relay.Therefore,this paper takes the no-load closing of the side winding of the converter transformer in a real converter station as an example to build the electromagnetic transient model of the transformer’s inrush current and analyzes the waveform of the transformer's inrush current under different remanence and closing angles.The finite element model of electromagnetic-force-current coupling of converter transformer was established to study the vibration characteristics of converter transformer under inrush current,and the characteristics of oil flow pressure and velocity in tank and tubing.The research results can provide an effective reference for the analysis of the fault mechanism of the rheo-changing gas relay under inrush current excitation.