Dynamic Stability of an Autonomous Microgrid Considering Active Load Impact With a New Dedicated Synchronization Scheme

Abstract

Similar to distributed generation inverters, active load has to use a dedicated synchronization unit such as a phase-locked loop (PLL) to get the reference voltage of the microgrid. To avoid PLL drawbacks, a new method is proposed to track the microgrid reference voltage for active load synchronization. An autonomous microgrid is modeled and designed. Additionally, the impact of active loads on the dynamic stability of the autonomous microgrid is investigated. An optimal design is performed to obtain the optimal controller parameters. Based on the time-domain simulation, the control design problem is optimally solved by minimizing a weighted objective function to limit the error in the dc voltage and the measured active power. Different step change disturbances are applied to examine and verify the effectiveness of the new synchronization method and the proposed controllers. Finally, a comparison between the proposed synchronization scheme and the traditional PLL is provided to prove the superiority of the proposed technique. It is concluded that the proposed synchronization method has a potential to enhance the microgrid stability efficiently. With the proposed method, PLL disadvantages such as design complexity, bad accuracy, nonlinearity, tuning difficulties, slow response, and negative impact on the control performance can be avoided.