基于特征值指标的光伏并网系统静态电压稳定性

Static voltage stability of photovoltaic grid-connected system based on eigenvalue index

随着可再生能源的持续发展,光伏电站呈规模化并网趋势,但光伏并网的无序发展会诱发光伏并网系统静态电压失稳问题。基于此,文中首先利用光伏的等效导纳构建光伏规模化并网系统的等效模型,将光伏并网对静态电压稳定性的影响量化为光伏等效导纳对导纳矩阵特征值的影响,得出导纳矩阵最小特征值减小会恶化光伏并网系统的静态电压稳定性的结论。随后,提出基于特征值-有功灵敏度的光伏并网系统静态电压稳定性评估指标,并且考虑导纳矩阵与光伏并网系统网络拓扑间的强相关关系,进一步分析网络拓扑对静态电压稳定性的影响,从交流和直流2个角度提出提升静态电压稳定性的光伏并网方案,得出合理改变输电网络拓扑能够提升光伏并网系统静态电压稳定性的结论。最后,基于IEEE 14节点系统算例验证了文中提出的特征值指标和光伏并网方案有利于保障光伏规模化并网系统的静态电压稳定性,推动光伏有序并网。

With the continuous development of renewable energy,photovoltaic power stations show a trend of large-scale grid connection,but the disorderly development of photovoltaic grid connection induces the static voltage instability in photovoltaic grid-connected system.Firstly,an equivalent model of photovoltaic large-scale grid-connected system using the equivalent admittance of photovoltaics is constructed in this paper,and the impact of photovoltaic grid-connected system on static voltage stability is quantified as the impact of photovoltaic equivalent admittance on the eigenvalue of the admittance matrix.It is concluded that the decrease of the minimum eigenvalue of the admittance matrix reduces the static voltage stability of photovoltaic grid-connected system.Further an evaluation index for static voltage stability of photovoltaic grid-connected system based on eigenvalue-active power sensitivity is proposed.Considering the strong correlation between the admittance matrix and the network topology of photovoltaic grid-connected system,the influence of the network topology on static voltage stability is analyzed.Photovoltaic grid-connected schemes which can improve the static voltage stability are proposed from AC and DC perspectives,and it is concluded that changing the topology of the transmission network reasonably can improve the static voltage stability of photovoltaic grid-connected system.Finally,based on a IEEE 14-node system example,the eigenvalue index and the photovoltaic grid-connected scheme proposed in this paper is validated to ensure the static voltage stability of large-scale photovoltaic grid-connected systems and promote orderly grid connection of photovoltaic system.