分压电路、电流互感器(TA)的比例误差和电流互感器的相角误差是谐波电能计量装置误差的主要来源。本文在分析谐波电能计量的电压、电流信号采集与调理等效电路基础上,建立了谐波条件下的电能计量比差、角差的误差模型,提出了谐波电能计量的比差与角差修正方法;针对宽量程仪用电流互感器的非线性误差,通过多项式曲线拟合得到了修正模型,据此提出了选取曲线拐点作为电能计量校准点的比差、角差分段线性化校正方法,提高了全测量范围内的谐波电压、谐波电流和谐波电能计量准确度。在本文算法基础上研制的三相多功能谐波电能表的基波有功误差≤0.2%,基波无功误差≤1%,2-21次谐波电压测量误差≤2%、谐波电流测量误差≤5%、谐波相位测量误差≤5。,满足GB/T-14549-93的A类谐波测量仪器要求。
Ratio errors of voltage-dividing circuit and current transformer (TA), and phase error of current transformer together constitute an important error source to harmonic energy measurement device. Based on some analysis upon the equivalent circuits for signal sampling and conditioning circuits of both voltage and current, the error mod- els of ratio error and phase error in energy measurement are established for signals containing harmonic components. A segment linearization correction method for ratio error and phase error is presented by choosing the turning points of the polynomial fitted curve as the calibration points to obtain the correction model, due to the nonlinear error of wide- range instrumentation current transformer. The metering accuracies of voltage, current and energy in the full measurement range can be improved. The three phase multi-functional harmonic energy meter based on the algorithm proposed in this paper has the following performance: the error of fundamental active power measurement is less than 0.2% , the error of fundamental reactive power measurement is less than 1% , the amplitude error of harmonic voltage is less than 2% , the phase error of harmonic current is less than 5% , and the phase angle error between harmonic voltage and current is less than 5 ^o. Above test results meet the accuracy requirement for the class A harmonic measurement instruments according to GB/T-14549-93.