考虑LVRT特性的规模化光伏并网系统频率响应建模方法

The paper proposes a frequency response modeling method for large-scale PV systems incorporating Low Voltage Ride-Through (LVRT) control. It characterizes the active power–frequency response path during severe voltage dips, establishes an equivalent time-domain active power expression for PV plants using capacity-weighted parameters and two-stage ramp fitting, and integrates LVRT-induced active power changes as segmented disturbances (step/ramp) into traditional frequency models to analyze RoCoF, nadir, and steady-state deviation.

含低电压穿越(LVRT)控制的光伏单元在电压大幅跌落时将采用无功优先原则,从而呈现有功出力变化,进而参与系统频率响应.为此,提出一种考虑规模化光伏LVRT特性的系统频率响应建模方法.首先,基于传统频率响应模型分析光伏规模化接入对系统的惯量水平、一次调频的影响,刻画电压大幅跌落场景下光伏电站控制切换行为引发的有功功率-频率的响应路径.然后,考虑光伏电站中单元众多、特性各异特点,归类3种典型LVRT有功特性并建立其划分边界,采用容量加权法计算光伏等值单元参数,并基于两阶段斜坡方法拟合非线性恢复集群的有功特性,建立光伏电站LVRT全过程的等值有功时域表达式.进一步地,将光伏电站LVRT有功变化量作为扰动激励引入传统频率响应模型,根据LVRT有功变化量时序特点,将其分段表征为阶跃、斜坡等形式,进而获取频率响应解析解,并由此分析LVRT特性对最大频率变化率、频率最大偏移和准稳态频率偏差等指标的影响.最后,在含光伏电站的5节点测试系统中验证所提建模方法的准确性和有效性.