基于频响法的电力变压器剩磁检测技术研究

Ｒesearch on Ｒesidual Magnetism Detection Technology of Power Transformer Based on Frequency Ｒesponse Method

摘要:

特高压交直流互联大电网是未来电网的发展方向,当换流站附近的大容量变压器带剩磁投入时,会出现较大励磁涌流,可能造成交直流电网故障。在长线路弱联系电网中,投带剩磁变压器产生的励磁涌流及和应涌流,会导致变压器差动保护误动和长时间的谐波电压,是电网安全稳定性的重要隐患。因此有必要对电力变压器剩磁的产生机理进行分析,探索剩磁检测方法,消除剩磁对电网的影响。对变压器进行去磁后,基于绕组的频率响应开展剩磁检测方法研究。研究结果表明,通过对一定扫频范围的频率响应进行对比,能准确地判断出变压器是否含有剩磁及剩磁含量的大小。

Abstract:

UHV AC/DC interconnected power grid is the main form of power grid in the future，and large capacity transformers are widely used． When the main transformer of a new substation is put into operation or put into operation after maintenance， large inrush current will appear in the transformer with residual magnetism，which has an important impact on AC and DC power grid． In the long － line weak － link power grid，the inrush current and sympathetic inrush current generated by the transformer with residual magnetism will lead to the disoperation of the transformer differential protection and the harmonic voltage for a long time，which is an important hidden danger of the security and stability for power grid． Therefore，it is necessary to analyze the generating mechanism of residual magnetism in power transformer，explore the detection method of residual magnetism，and eliminate the influence of residual magnetism on power grid． The demagnetization test is carried out for the transformer，and based on the frequency response of winding，the residual magnetism detection method has been studied． The research results show that: by comparing the frequency response in a certain sweep frequency range，it can accurately determine whether the transformer contains residual magnetism，and can determine the magnitude of the residual magnetism content of the transformer．