【摘要】 对于采用主从控制策略的微网系统,如何实现并网/孤岛工作模式之间的无缝切换是一项亟待克服的技术难点。首先介绍微网系统的基本结构和工作模式,结合微网系统并网/孤岛工作模式切换时的工作特征,提出一种改进的电压环调节器结构。即根据能量守恒原则,在工作模式切换前预先估算并设置调节器的输出需求,可较好地解决切换过程中微网母线电压的震荡和电流冲击等问题。其次,提出一种适合微网的软件锁相方法,保证各种切换条件下微网母线电压相位的连续性和平顺性,为不同工作模式间的无缝切换奠定基础,并对储能变流器的控制参数进行了优化设计。最后,建立微网系统的仿真模型和完善的实验验证平台,仿真和实验结果共同验证了所提控制策略和锁相方法的有效性和优越性。更多还原

【Abstract】 For microgrid(MG) system with master-slave control strategy, seamless transfer between grid-connected and islanding operation remains a technical barrier, which needs to be solved urgently. In this paper, the structure and operation principle of the MG was firstly investigated. According to the dynamic behavior exhibited in the mode transfer process, an improved proportional-integral(PI) controller for voltage-loop was proposed. By using energy conservation theorem, the output value of the new PI controller can be calculated and preset for next operational mode before mode transfer. Thus, the vibration and overshot problem of local AC bus could be well reduced, even eliminated. Also, a novel phase-locked loop(PLL) for MG application was presented. The phase angle of AC bus can be maintained smoothly and successively during different kinds of mode transfer condition, which makes the seamless transfer between grid-tied and islanding operation possible. Then, optimized parameters of the controller were derived for main converter with mathematical model and engineering experience. Both simulation and experimental platform were established, simulation and experimental results verify the effectiveness and superiority of the proposed strategies.更多还原