基于电网谐波阻抗估计的并联电容器组优化配置方案

采用先投入高串抗率电容器、后投入低串抗率电容器这种单一配置方案，导致变电站出现高串率电容器频繁投切、寿命降低和无功容量浪费问题。为了解决这些问题，提出一种基于阻抗估计和多电能质量约束的变电站电容器组优化配置方法。首先，获取电容器投切后公共连接点母线电压电流数据；其次采用小波最大最小阈值去噪，通过Prony算法得到暂态电压、电流数据来估计系统谐波阻抗，最后结合AVC下达的调度指令和目标函数在满足电网电能质量约束条件下对电容器组进行优化配置。结果表明，在满足电能质量约束和AVC调度指令下，优化配置后高低串抗率配置频次均有所改善，高串抗率电容器组投入频次下降32%,低串抗率电容器组投入频次由26%提高至58%。由系统谐波数据、谐波源和电容器等元件组成的谐波阻抗模型，以及基于谐波谐振机理设计的电容器组配置方案，能够提高数据分析的准确性，减小电容器损坏以及解决无功容量损失问题，提高供电质量，可为变电站电容器组的配置提供借鉴。

Optimal configuration of parallel capacitor banks based on grid harmonic impedance estimation

In order to improve the problems of frequent switching, lifetime reduction and reactive power capacity waste of high-series capacitors caused by the single configuration scheme of putting in high-series capacitors first and low-series capacitors later in substations, an optimal configuration method of substation capacitor bank based on impedance estimation and multiple power quality constraints was proposed. Firstly, bus voltage and current data of common connection point was obtained after capacitor switching, the wavelet maximum-minimum threshold was used to denoise, the transient voltage and current data were obtained by Prony algorithm to estimate system harmonic impedance, and the configuration of capacitor banks under the grid power quality constraints was optimized, combining with the scheduling instructions from the AVC (automatic voltage control) and objective functions. The results show that, under the condition of satisfying the power quality constraints and AVC dispatching command, the frequency of both high and low series impedance configuration is improved after the optimized configuration, and the frequency of high series impedance capacitor bank input decreases by 32%, while the frequency of low series impedance capacitor bank input increases from 26% to 58%. The harmonic impedance model consisting of system harmonic data, harmonic sources and capacitors, and the capacitor bank configuration scheme designed by the harmonic resonance mechanism improves the accuracy of data analysis, reduces capacitor damage and reactive capacity loss, and improves the quality of power supply, which can provide reference for the configuration of substation capacitor banks.