基于惯性自适应的并网逆变器虚拟同步发电机控制

Virtual synchronous generator control of a grid-connected inverter based on adaptive inertia

虚拟同步发电机(Virtual Synchronous Generator,VSG)控制方法下的并网逆变器(Grid-Connected Inverter,GCI)在电网工况突变情况下存在输出功率和频率的超调和振荡现象。为改善GCI的动态性能,提出一种基于惯性自适应的VSG控制方法。该方法直接对采用VSG控制方法的GCI的功角曲线和输出特性曲线进行分析,推导出GCI的输出功率和频率变化率之间的关系。通过利用GCI虚拟输出功率和参考功率的偏差判断系统的四个加减速运行区间,避免对输出频率变化率的依赖。构造惯性自适应控制算法,通过参数的连续平滑调节,抑制GCI的输出功率和频率的波动。与现有方法相比,该方法不需要对频率直接微分,避免引入系统噪声;同时惯性参数能够连续调节,且变化范围更大。仿真结果验证了所提方法的正确性和有效性。

A grid-connected inverter(GCI)based on a virtual synchronous generator(VSG)control may cause overshoot or oscillation of output power and frequency under fluctuation conditions.A VSG control method based on an inertial adaptive algorithm is proposed to improve the dynamic performance of a GCI.This method directly analyzes the power angle and output characteristic curves of a GCI based on VSG control,and deduces the relationship between the output power and the frequency change rate.By judging the four acceleration and deceleration operation intervals of the inverter,the deviation between the virtual output active power and reference power is employed to avoid dependence on the change rate of the output frequency.With an adaptive control algorithm,the parameters can be adjusted continuously and smoothly,so that the frequency and output power fluctuations of the GCI can be restrained.Compared with existing methods,the proposed method does not require frequency differentiation directly.This avoids the introduction of system noise.It can also achieve a wider range of continuous adjustment of inertial parameters.Simulation results verify the correctness and effectiveness of the proposed method.