摘要
并网逆变器通常使用锁相环获取电网电压同步信息。在弱电网中,电网阻抗不可忽略,公共耦合点处的电压扰动使得锁相环输出相角存在偏差,从而影响对并网电流的控制,不利于并网逆变器的稳定运行。为抑制锁相环引入的扰动、增强并网系统的稳定性,提出一种基于非理想广义积分器的改进小信号补偿控制方法。首先,在dq坐标系下建立考虑锁相环影响的LCL型三相并网逆变器小信号模型。然后,分析加入小信号补偿前后并网逆变器等效输出阻抗的变化特征,针对小信号补偿方法对稳定裕度的提升效果随频率升高减弱这一问题,在小信号补偿的基础上加入微分补偿通路,微分项由非理想广义积分器等效替代。在电网阻抗宽范围变化时,采用所提方法可以确保并网逆变器始终保持良好的稳定裕度,增强了并网逆变器的稳定性和动态性能。最后,通过实验验证了理论分析的正确性和所提方法的有效性。
The grid-connected inverter usually uses the phase-locked loop(PLL) to obtain the grid voltage synchronization information. In a weak grid, the grid impedance cannot be ignored. The voltage disturbance at the common coupling point leads to the output phase angle deviation of the PLL, and then affects the control of the grid-connected current, which is not conducive to the stable operation of the grid-connected inverter. In order to suppress the disturbance introduced by the PLL and enhance the stability of the grid-connected system, an improved small-signal compensation control method based on a non-ideal generalized integrator is proposed. First, the small-signal model of an LCL three-phase grid-connected inverter with the influence of the PLL is established in the dq coordinate system. Then, the variation characteristics of the equivalent output impedance of the gridconnected inverter with and without small-signal compensation are analyzed. For the problem that the improvement effect of the small-signal compensation method on stability margin declines with the increasing frequency, a differential compensation path is introduced based on the small-signal compensation, in which the differential term is equivalently replaced by a non-ideal generalized integrator. When the grid impedance changes in a wide range, the proposed method can ensure a good stability margin for the gridconnected inverter, and enhance the stability and dynamic performance of the grid-connected inverter. Finally, the correctness of the theoretical analysis and the effectiveness of the proposed method are verified by experimental results.
作者
姜云龙
司鑫尧
史鸿飞
竺明哲
葛乐
JIANG Yunlong;SI Xinyao;SHI Hongfei;ZHU Mingzhe;GE Le(Electric Power Research Institude of State Grid Jiangsu Electric Power Co.,Ltd.,Nanjing 211103,China;School of Electric Power Engineering,Nanjing Institute of Technology,Nanjing 211167,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2022年第24期113-120,共8页
Automation of Electric Power Systems
基金
国家自然科学基金资助项目(51707089)。
关键词
并网逆变器
弱电网
锁相环
非理想广义积分器
稳定裕度
grid-connected inverter
weak grid
phase-locked loop(PLL)
non-ideal generalized integrator
stability margin
