基于线性自抗扰的微电网平滑切换控制策略

Control Strategy for Microgrid Seamless Switching via Linear Active Disturbance Rejection

实现微电网并网/孤岛运行模式平滑切换是保证微电网安全可靠运行的前提。提出了基于线性自抗扰控制(linear active disturbance rejection control,LADRC)技术的微电网运行模式平滑切换控制策略。以主从结构的微电网为研究对象,将主控单元电压外环控制器设计为LADRC控制器,采用扩张状态观测器(extended state observer,ESO)对扩张状态(未知过程扰动、系统未建模摄动及dq轴通道耦合)进行在线实时估计,并将扰动估计主动补偿于主控单元的电流内环设定值中,从而达到快速消除扰动、平缓切换过程的效果。推导出一阶LADRC及主控系统的传递函数并进行幅频分析,结果表明所提方案具有良好的设定值跟踪性能和扰动抑制性能。动态仿真结果表明,所提控制策略能够有效平滑微网由并网切换至孤网模式产生的暂态振荡,同时对从控部分的扰动具有较好的鲁棒性,并且算法简单、调试容易。

A novel seamless switching strategy for microgrid operation between grid-connection and island modes was proposed based on its essential premise of microgrid security and reliability.Taking a microgrid with master/slave control mode as research object,the outer voltage controller of the master control unit was designed based on principle of linear active disturbance rejection control（LADRC）.Since extended state observer（ESO） estimated the total real-time disturbances by taking them as an extended state,these disturbances can be compensated actively to the settings of inner current loop,resulting in quick disturbance elimination and smooth transition operation.The transfer functions of the first order LADRC and master control system were deduced and amplitude-frequency analysis demonstrated superiority of the proposed strategy in setting tracking and disturbance rejection performance.Simulation results show that it can smooth transient oscillation during switching process effectively and possesses strong robustness;and it is easy to tune and implement.