变压器漏感参数的计算

由于变压器内部磁路本身的特点和励磁涌流波形受多种因素的影响,使得变压器差动保护存在多种误动的可能。功率差动原理、磁通特性识别法、等值电路参数鉴别法及基于变压器的回路方程法等摆脱了励磁涌流及过励磁的影响,实现了与差动保护不同的保护思路,但都要求预知原副边绕组电阻和漏感参数。绕组电阻可以通过测量得到,关于漏感尚无精确的求取方法。鉴于此种情况,本文提出了一种参数辨识方法,通过测量稳态瞬时电压和电流,利用最小二乘法能够快速准确辨识出原副边绕组漏感,为新型保护原理的推广奠定了基础。并且讨论了不同采样频率和截止频率下辨识结果的误差。通过电磁暂态仿真程序EMTP仿真和实际的变压器试验,验证了该算法的正确性,误差很小,具有极好的应用价值。

Calculation of the leakage inductances of Y/? transformer

The characteristics of internal magnetic circuit of transformer and the inrush current waveform affected by many factors make the possibilities of malfunction of the transformer differential protection exist.Power differential principle,the identification of magnetic flux characteristics,identification of equivalent circuit parameters and the algorithm of loop equation based on the transformer avoid the impact of inrush current and over-excitation and implement different protection ideas from the differential protection.However,they all require knowing predictably the winding leakage inductance and resistance of each winding of the transformer as priori parameters.Coil resistance can be measured,there is no precise method for the computation of leakage inductance.Given such circumstances,this paper proposes a parameter identification method by measuring the steady-state transient voltage and current.Using least-squares method it can identify the winding leakage inductance and resistance of each winding quickly and accurately and lay a foundation for the promotion of new types of protection principle.At the same time,this paper has discussed the errors of identification results at different sampling rates and the cutoff frequency,verified the correctness of this algorithm by the simulation of electromagnetic transient simulation program EMTP and the experiment of real transformer and had an excellent applicable value.