基于LCL滤波器优化的微电网多逆变器稳定运行控制系统

Control System for Stable Operation of Multiple Inverters in Microgrid Based on Optimization of LCL Filter

为了有效控制逆变器谐振现象,保障逆变器稳定运行,设计基于LCL滤波器优化的微电网多逆变器稳定运行控制系统。依据LCL多逆变器拓扑结构,创建LCL滤波器三相微电网多逆变器的状态空间数学模型。依据该数学模型,分析滤波器的谐振特性,采用2个互相独立的单相逆变器实现对平衡三相LCL逆变器中谐振控制,利用单相LCL逆变器完成控制策略研究;利用被动阻尼策略,通过电容支路串、并联阻尼法对LCL滤波器的逆变器进行振荡控制优化;利用主动阻尼策略,在不添加其他传感器和控制闭环的条件下,运用2对零极点使闭环系统中全部的主导极点都在垂直平面单位圆中,抑制LCL滤波器谐振问题,以实现系统稳定运行控制优化。实验表明,该方法通过主动阻尼和被动阻尼控制策略对LCL滤波器进行优化,能够确保微电网多逆变器的母线电压以及暂态波形的稳定,控制效果好。

To effectively control the resonance of an inverter and ensure its stable operation,a control system for the stable operation of multiple inverters in microgrid based on the optimization of an LCL filter is designed.According to the LCL multi-inverter topology,a state-space model of multiple inverters in the LCL filter three-phase microgrid is established.Based on this model,the resonance characteristics of the filter are analyzed,two independent single-phase inverters are used to realize the resonance control of the balanced three-phase LCL inverter,and the single-phase LCL inverter is used to complete the control strategy.Under the passive damping strategy,the capacitor branch series and parallel damping method is used to optimize the control of oscillations in the LCL filter inverter.Under the active damping strategy,without adding additional sensors or closed-loops,two pairs of zero-poles are used to ensure that all the dominant poles in the closed-loop system are in the vertical plane unit circle,thus suppressing the LCL filter resonance problem to achieve the optimization of system stable operation control.Experimental results show that by optimizing the LCL filter through the active damping and passive damping control strategies,the proposed method can ensure the stability of bus voltage and transient waveform of multiple inverters in microgrid,indicating a satisfying control effect.