基于无相位实测数据的系统侧谐波阻抗估计方法改进

An Improved Utility Harmonic Impedance Estimation Method Based on Measurement Data without Phase Angle

当实测数据相位角缺失时,现有计算谐波阻抗方法通常失效。由此,该文提出一种无需测量数据相位角而仅需测量点谐波电压、电流幅值及其相位差的系统侧谐波阻抗计算新方法。所提方法首先依据系统短路容量估算系统侧谐波阻抗初值并反解出相应的背景谐波电压,再排序分段该背景谐波电压。据此,依据各段背景谐波电压与相应测量数据之间的弱相关性计算各段数据对应的谐波阻抗,并根据谐波阻抗波动最小准则求取真实谐波阻抗。所提方法不依赖于阻抗初值的选取,当用户侧谐波阻抗非远大于系统侧谐波阻抗且背景谐波波动较大时,所提方法仍能取得好的评估效果,有效解决了实测数据相位缺失时系统侧谐波阻抗计算难题。仿真和实测数据验证了所提方法的有效性。

When the phase angle of the measured data is missing,the existing method of harmonic impedance estimation usually fails.Therefore,this paper presented a new method to calculate the utility harmonic impedance,which is no need to measure the phase angle of the data but only needs to measure the amplitude of harmonic voltage/current and their phase differences.The proposed method first estimated the initial value of the utility harmonic impedance based on the short-circuit capacity of the system and reversely solved the corresponding background harmonic voltage,and then sorted and segmented the background harmonic voltage.According to the weak correlation between the background harmonic voltage of each section and the corresponding measured data,the harmonic impedance corresponding to each section of the data was calculated,and then the true harmonic impedance was calculated according to the minimum principle of harmonic impedance fluctuation.The proposed method does not depend on the selection of the initial value of impedance.When the harmonic impedance of the customer side is not much greater than that of the system side and the background harmonic wave is large,the proposed method can still achieve good evaluation results,and effectively solve the problem of calculating the utility harmonic impedance when the phase of measured data is missing.The effectiveness of the proposed method was verified by simulation and field data.