微电网多逆变器运行的自适应下垂控制新策略

摘要

Due to the island operation of low voltage micro grid is affected by the influence of such factors as the non-consistence of line impedance,the traditional droop control can't distribute power according to the unit capacity of the distributed power (DG) reasonably,therefore this paper proposes a new self-adaptive droop control strategy.The paper analyzes the electrical characteristic of inverters in parallel operation and in the mode of the island operation and virtual impedance technology and the traditional droop control strategy.Then,it designs the virtual impedance and P-U droop control loop of inverter and remains traditional Q-f droop control loop unchanged.The principle of designing P-U droop control loop is based on utilizing the integral of active power P to lock the voltage difference and using sine function to solve the problem of output voltage falling over time caused by the integral,in the mean time,utilizing linear differential adjustment of traditional P-U droop control droop to improve the speed of adjustment and the design and distributes the active power P effectively.The simulation results show that,comparing with the deviating regulation of traditional droop control strategy,the proposed strategy can realize zero error output adjustment and not be affected by the changing of output impedance and line impedance.%由于低压微电网在孤岛模式下受线路阻抗不一致等因素的影响,传统的下垂控制无法按分布式电源(DG)单元容量合理均分功率,为此提出了一种新的自适应下垂控制策略.文章分析了微电网孤岛模式下逆变器并联运行的电气特性、虚拟阻抗技术以及传统下垂控制策略,重新设计了逆变器的输出阻抗和P-U下垂控制环,不改变传统的Q-f下垂控制环.P-U下垂控制环的设计原理是根据有功功率P的积分来锁定压差,通过正弦函数解决积分项引起输出电压随时间不断下降的问题,同时利用传统P-U下垂控制环的线性有差调节项提升调节速度,最终使有功功率P得到有效均分.通过仿真结果表明,与传统下垂控制的有差调节相比,该策略可实现无差调节且不受输出阻抗和线路阻抗变动的影响,实现功率的合理均分.