改善微电网电能质量的分层控制策略研究

Hierarchical control strategy on improving power quality of micro-grid

微电网技术具有许多优点,但分布式电源的不稳定性将导致微电网不易运行控制,对微电网的电能质量产生不利影响。针对此问题,提出了分层控制策略,以改善和提高微电网的电能质量。分层控制包含上下2层,通过上层将控制信息发送到下层实现。其中,初级控制采用下垂控制方法,提出了基于电压外环、电流内环和功率环的反馈控制器。二级控制(secondary control)通过向初级控制(primary control)反馈二级控制后控制逆变器的输出电压幅值和频率,使之重新达到平衡,实现系统运行的稳定性。利用Matlab/simulink仿真结果表明:该分层控制策略对改善微电网电能质量是有效的。

Micro-grid technology has many advantages,however,the instability of distributed generations makes micro-grid difficult in operation and control,producing adverse effects on the grid＇s power quality. To improve power quality of the micro-grid, the hierarchical control is proposed. The hierarchical control contains two levels：the upper level＇s output control signal will be set as input control signal of the lower level. In this control system,the primary control adopts droop control method to propose feedback controller based on voltage outer loop,current inner loop and power loop etc. The secondary control uses the output voltage magnitude and frequency fed back to the primary control to control the inverter,making these signals balanced again,keeping the system stable. The results of simulation in Matlab/simulink show that the hierarchical control is effective to improve power quality of micro-grid.