摘要
基于电阻和电容并联或串联等效电路模型提出了一种在非整周期情况下仍有较高精确度的介损数字化算法。测量电容型设备绝缘上的电压和泄漏电流信号后使用傅里叶算法或加窗插值傅里叶算法和修正理想采样频率法获得信号的谐波分量,分别根据阻容并联/串联等效电路模型以及电压信号对电流信号进行拟合,并将拟合模型中的变量进行适当的转化后使模型由非线性最小二乘变为线性最小二乘,直接计算获得电阻、电容进而得到介损和拟合泄漏电流信号,从而简化了计算。对仿真信号和实测信号的处理结果表明:阻容并联和阻容串联模型均能较好拟合电流信号,前者精度稍高;根据等效模型算法拟合后的电阻、电容计算所得介损在不同信号频率下仍有较高精确度,且该方法可获得绝缘的等效电阻和电容。
A dielectric loss digital algorithm based on parallel or series equivalent circuit model of resistance and capacitance is proposed,and the algorithm still has high accuracy in non-integer periods sampling.In the paper,the voltage and leakage current signal of capacitive electrical equipment insulation are measured,and those signal harmonics are obtained by the Fourier algorithm or the windowing and interpolation Fourier algorithm and modified ideal sampling frequency method. The leakage current signal is fitted by the parallel/series equivalent circuit model and the voltage signal.In the meantime,variance of the model is transformed to make the model turn from a non-linear least square model into a linear least square model,which has less calculation work,then the resistance and capacitance of the circuit model is calculated directly.After then,the dielectric loss and the fitted leakage current signal of the capacitive equipment are obtained.The above algorithms are used to process the simulated and real measured signals,and the result indicates that the leakage current signal can be fitted well by parallel or series equivalent circuit model,and the former has higher fitting accuracy;the dielectric loss calculated by the proposed algorithms is accurate in different signal frequencies,in the meantime the algorithm can give equivalent resistance and capacitance.
出处
《电力系统保护与控制》
EI
CSCD
北大核心
2011年第11期74-78,共5页
Power System Protection and Control
基金
国家重点基础研究发展计划项目(973项目)(2009CB724508)
关键词
电气设备
电介质
介质损耗
等效电路模型
最小二乘
频率
electrical equipment
dielectric
dielectric loss
equivalent circuit model
least square
frequency
