含SVG的双馈风场风速变化条件下高频谐振问题分析

Analysis of high frequency resonance problem in doubly-fed wind field systems with SVG with wind speed variation

大规模风电并网导致宽频谐振问题日渐凸显,业内多认为电缆电容效应、控制器参数变化等是导致谐振的主要因素,而关于静止无功发生器(static var generator, SVG)、风功率变化与高频谐振内在因果关系研究尚未展开。针对低风速风场系统高频谐振问题,首先基于谐波线性化理论,考虑功率外环作用,建立SVG和双馈风机(doubly-fed induction generator, DFIG)的序阻抗模型。其次将风速变化纳入风机变流器建模,并建立空载电缆投入时风速变化与SVG阻抗的联系。然后利用阻抗交互揭示风机变流器阻抗变化对SVG阻抗特性的影响机理,指出区域内空载电缆投入后,低风速不仅降低系统在高频的鲁棒性,而且扩大了SVG高频负阻尼范围,导致系统高频谐振风险增加。最后,基于STARSIM-HIL搭建含SVG的双馈风场电磁仿真模型,并进行软硬件在环实验。实验结果证明了理论分析的正确性。

The large-scale integration of wind power into the grid has led to increasingly prominent broadband resonance problems.Industry experts believe that cable capacitance effects,controller parameter changes,etc.are the main factors causing resonance.However,research on the inherent causal relationship between the static var generator(SVG),wind power changes,and high-frequency resonance has not yet been conducted.This paper focuses on the high-frequency resonance problem of low wind speed wind field systems.First,based on harmonic linearization theory and considering the effect of the power outer loop,the sequence impedance models of an SVG and a doubly fed induction generator(DFIG)are established.The wind speed changes are incorporated into the modeling of the wind turbine inverter,and the relationship between wind speed changes and SVG impedance is established when the no-load cable is put into operation.The impedance interaction is used to reveal the mechanism of the influence of wind turbine inverter impedance changes on SVG impedance characteristics.It is pointed out that after the deployment of unloaded cables in the area,low wind speed not only reduces the robustness of the system at high frequencies,but also expands the negative damping range of the SVG at high frequencies,leading to an increase in the risk of high-frequency resonance in the system.Finally,a doubly fed wind field electromagnetic simulation model containing an SVG is constructed based on STARSIM-HIL,and software and hardware in-the-loop experiments are conducted.The experimental results proved the correctness of the theoretical analysis.