含ＳＶＧ 的光伏场站阻抗建模与高频振荡风险分析

mpedance Modeling and Risk Analysis of High Frequency Oscillations of Photovoltaic Stations with Static Var Generator

摘要:

基于级联H桥电路的静止无功发生器（SVG）具有快速的动态无功支撑能力，是大型光伏场站常用的无功补偿设备。同时，由于SVG的控制带宽相对较大，控制作用所影响频段范围相对较宽，SVG在千赫兹以上的高频段仍可能具有负阻特性，使得含SVG的光伏场站面临更高频段范围的高频振荡风险。然而，现有研究重点关注新能源在2.5 Hz～1 kHz频段范围内的阻抗特性，无法评估1 kHz以上的高频振荡风险。同时，多种高频段附加控制策略和多种运行方式使得光伏场站的高频振荡分析进一步复杂化。首先，围绕含SVG的光伏场站高频振荡问题，建立了计及多类型附加控制策略影响下光伏机组和SVG的高频通用阻抗模型；进而，深入分析了光伏场站的高频段阻抗特性及其高频段负阻尼的影响因素，提出了含SVG的光伏场站面临的典型高频振荡风险；最后，针对四川某光伏场站开展电磁暂态仿真，对所做研究内容进行了验证。

Abstract:

The static var generator (SVG) is based on a cascaded H-bridge circuit, and has fast dynamic reactive power support capability, which is commonly used as a reactive power compensation equipment in large photovoltaic (PV) stations. Due to the large control bandwidth of SVG, the affected frequency range is relatively wide, SVG can still have negative resistance characteristics in high frequency range above kHz, which makes PV stations with SVG face the risk of high frequency oscillations in the higher frequency range. However, the existing researches focus on the impedance characteristics of renewables from 2.5 Hz to 1 kHz, which cannot evaluate the risk of high frequency oscillations above 1 kHz. Meanwhile, various high frequency additional control strategies and a variety of operating conditions make the analysis of high frequency oscillations of PV stations further complicated. So the high-frequency universal impedance model of PV units and SVG is established considering the influence of various additional control strategies. Furthermore, the high frequency impedance characteristics and the influence factors of high frequency negative damping of PV stations are analyzed, and the typical high frequency oscillation risk of PV stations with SVG is proposed. Finally, the electromagnetic transient simulation of a PV station in Sichuan is carried out to verify the proposed research contents.