School of Electrical Engineering, North China University of Water Resources and Electric Power

目的目的为解决当前大规模新能源发电并网后电力系统低惯量运行的问题,方法方法对并网逆变器惯性特性进行分析,并对提升并网逆变器惯性水平的方法进行研究。首先分析电力系统中惯性的本质,推导出并网逆变器惯性水平与自身器件参数的关系,利用根轨迹法绘出以直流侧电容为变量的直流电压控制环根轨迹,结合根轨迹和不同电网工况场景对逆变器惯性水平的需求优化直流侧电容取值;然后在并网逆变器直流侧电压控制环中引入频率反馈环节,提出一种改进的逆变器直流侧电压控制策略和逆变器调制策略,进而提升并网逆变器的瞬时惯量水平,使直流侧电容根据电网频率波动情况进行充放电,抑制电网频率瞬时变化率;最后,使用MATLAB/Simulink搭建仿真平台对所提惯性提升策略进行验证。结果结果结果表明,当直流侧电容取0.4F,虚拟惯性时间常数为5s时,与未使用本文所提控制策略相比,本文策略的系统频率跌落最大偏移量减小了0.11Hz,平均跌落速率减小了0.035Hz/s。结论结论所提策略能有效提升并网逆变器惯性水平,抑制电网频率瞬时变化。

Objectives To address the problem of low inertia operation in the power system caused by the in‑tegration of a large-scale new energy source, Methods the inertia characteristics of grid-connected inverters were analyzed and methods of improving their inertia level were studied. Firstly, the essence of inertia in the power system was analyzed,and the relationship between the inertia level of grid-connected inverters and their device parameters was derived. The root locus method was used to plot the root locus of the DC-side voltage control loop with the DC-side capacitance as a variable. The value of the DC-side capacitance was optimized based on the root locus and the requirements for inverter inertia level under different grid conditions. Then, a frequency feedback loop was introduced into the DC-side voltage control loop of the grid-connected inverter, and an improved control strategy for the DC-side voltage and modulation strategy for the inverter were proposed to enhance the instantaneous inertia level of the grid-connected inverter. This allowed the DC-side capacitance to charge and discharge according to the fluctuation of the grid frequency, suppressing the instantaneous rate of change of the grid frequency. Results The proposed inertia enhance‑ment strategy was validated using MATLAB/Simulink simulation platform. It was found that compared with the proposed strategy not used, when the DC-side capacitance was set to 0.4 F and the virtual inertia time constant was 5 s,the maximum deviation of the system frequency drop was reduced by 0.11 Hz,and the average drop rate was reduced by 0.035 Hz/s. Conclusions The proposed strategy could effectively improve the inertia level of grid-connected inverters and suppress the instantaneous variation of the grid frequency.

国家自然科学基金资助项目(U1804149)

李继方,韩爱山.并网逆变器惯性特性与提升策略研究[J].河南理工大学学报(自然科学版),2025,44(1):134‑144.

LI J F, HAN A S. Research on inertia characteristics and lifting strategy of grid-connected inverter[J]. Journal of Henan Polytechnic University (Natural Science),2025,44(1):134-144.