微电网电压分层控制与补偿机制研究

Study on hierarchical control and compensation mechanism of micro-grid voltage

微电网技术具有许多优点,然而微电网中的分布式电源自身的不稳定性会导致微电网的运行控制困难,特别是公共连接点处会出现电压不平衡。为了补偿此不平衡电压,提出了分层控制方法。该方法将电网运行控制分为上下2层,由上层控制发送控制信号,并由下层控制来实施,此控制信号与正序电压分量和负序电压分量有关;在dq旋转坐标下,依靠同步坐标系锁相环(SRF-PLL)和解耦的双同步坐标系锁相环(DDSRF-PLL)等并网同步技术将微电网同步地接入电网,并通过控制逆变器得到电压幅值。仿真结果表明:分层控制方法能够较好地实现对微电网的控制。

Micro-grid technology has many advantages. However,the instability of distributed generations in the micro-grid will lead to difficulty in operation controlling of the grid,especially the voltage at the point of common coupling (PCC) could be unbalanced. Consequently,the hierarchical control method is proposed to compensate this unbalance voltage. In this control method,the hierarchical control structure is composed of two levels. The upper control level sends control signals to control the lower control level. These control signals are the positive- and negative-sequence components of the unbalanced voltage. Micro-grid adopts rotating dq frame based synchronization technology,such as synchronous reference frame phase-locked loop (SRF -PLL)and decoupled double synchronous reference frame phase-locked loop(DDSRF- PLL)etc.. The micro-grid is synchronously connected to the electricity grid,and gains voltage magnitude by controlling the inverter. Matlab/Simulink software is used to set up the simulation model of connecting micro-grid to the main grid. The simulation results show that the hierarchical control method is effective to implement micro-grid control.