网间规模化光伏并网对系统阻尼的影响及优化措施

Study on the influence of large-scale PV grid-connected systems on the oscillation damping characteristics and optimization measures

电力系统受到大扰动后,其振荡中心电压大幅波动,受此影响,其近区规模化光伏汇集线功率会出现显著波动,加剧光伏与电网交互作用。文章基于光伏暂态仿真模型,分析了并网电压低频跌落或回升过程中,光伏并网系统暂态功率特性;基于等面积原理,分析了不同控制方式下光伏并网系统等值电纳Bpv的Us-Bpv轨迹及其对振荡的影响,并据此揭示了光伏并网系统对电网振荡阻尼的作用机制。通过两区域四机系统受扰时域仿真,验证了基于光伏并网系统Us-Bpv轨迹特征,评估其对系统阻尼影响的有效性,在此基础上,指出利用附加阻尼控制的SVG具有增强系统正阻尼作用。

After large disturbances, there is large fluctuation in the voltage of oscillation center of power grid. Affected by this, photovoltaic grid-connected system adjacent to the oscillation center will appear significant fluctuations, which will increase the interaction between it and the power grid. This paper is based on photovoltaic transient simulation model, in the process of low frequency drop and recovery of grid voltage, the transient power characteristics of photovohaic connected system is analyzed. According to the equal area principle, when scale PV grid- connected system is under different control modes, the influence of the Us-Bpv trajectories on the oscillation damping is analyzed, and the effect mechanism of photovohaic system on the oscillation damping is revealed. In this paper, the two-zone four-machine system disturbed time domain simulation is taken as an example. The effectiveness of influence on the system damping evaluated according to the Us-Bpv trajectories characteristic of photovoltaic grid connected system is verified. On this basis, the damping optimization measure of the photovohaic grid connected system with SVG additional damping control is proposed.