基于最小范数的系统侧谐波变阻抗求解技术

系统侧谐波阻抗计算对新型电力系统的安全稳定运行有至关重要的意义。在谐波阻抗估计算法中，通常假设谐波测量阻抗、电网侧电压在测量周期中恒定不变。实际上电网为动态的网络，电网运行方式时常发生改变，从而导致谐波阻抗大小呈现波动的状态，电网侧电压也随着负荷的变化而不断变化。因此，谐波阻抗以及电网侧电压也是随时间不断变化的，但相邻采样时间内变化并不大。本文提出了一种新的系统侧谐波阻抗估算方法，以测量周期内相邻采样时间的阻抗变化量和电压变化量的最小范数为标准来估算谐波阻抗。在测量周期内建立目标函数，通过最小化目标函数获得谐波阻抗。通过仿真和现场实际案例分析，验证了该方法在高谐波背景和用户侧谐波阻抗小于电网侧谐波阻抗的条件下的准确性和可靠性。

Solution technology of system side harmonic variable impedance based on minimum norm

The calculation of system side harmonic impedance is of great significance to the safe and stable operation of the new power system. In the harmonic impedance estimation algorithm, it is usually assumed that the harmonic measurement impedance and grid side voltage are constant during the measurement period. In fact, the power grid is a dynamic network, and the operation mode of the power grid often changes, resulting in the fluctuation of the harmonic impedance, and the voltage on the power grid side also changes with the change of load. Therefore, the harmonic impedance and the voltage on the grid side also change with time, but the change is not large in the adjacent sampling time. This paper presents a new method for estimating the harmonic impedance of the system side. The harmonic impedance is estimated based on the minimum norm of the impedance variation difference and voltage variation difference between adjacent sampling times in the measurement period. The objective function is established in the measurement period, and the harmonic impedance is obtained by minimizing the objective function. Through simulation and field case analysis, the accuracy and reliability of this method are verified under the condition of high harmonic background and the harmonic impedance on the user side is less than that on the grid side.