含多种分布式电源的微电网控制策略

针对微电网的并网与孤岛运行方式以及2种运行方式之间的转换,提出了一种含多种分布式电源的微电网控制策略。该控制策略中微电网中心控制器连续监测微电网和大电网的运行状态并对微电网进行统一的协调控制:对于并网运行的微电网,当检测到孤岛状态时立即切换到孤岛运行控制方式;对于孤岛运行的微电网,通过选择主调频电源实现微电网频率的无差调节,避免了下垂控制产生的频率偏差;微电网重新并网时,通过采用电压灵敏度分析方法调节并网接口处的电压幅值并监视与大电网的电压相位差,实现微电网运行方式的平稳切换。采用PSCAD/EMTDC软件对含多种分布式电源的微电网进行仿真分析。仿真结果表明,提出的控制策略能够维持微电网的稳定运行,并能实现微电网并网与孤岛运行方式的平稳过渡。

Control strategy of microgrid with different DG types

According to the grid-connected and islanded operating modes of microgrid and the changeover between them,a control strategy of microgrid with different kinds of DG(Distributed Generation) is proposed,which monitors the operating states of both microgrid and power network and provides the unified coordinating control by the central controller of microgrid.When the islanded operating state is detected,the microgrid is changed over from grid-connected control mode to islanded control mode immediately.In islanded mode,a DG is selected as the master for no-error frequency regulation of microgrid to prevent the frequency error caused by droop control.The voltage amplitude of the connecting point is adjusted by the voltage sensitivity analysis and its phase deviation from power grid is monitored for the re-connection of microgrid to power network.Results of simulation with PSCAD/EMTDC demonstrate that,the proposed strategy keeps the stable operation of microgrid and implements the bumpless changeover between two operating modes.