Dynamic performance improvement of an inverter-based grid-connected microgrid

In this paper, a new control technique for stability improvement of the grid connected microgrids is proposed. Grid connected microgrid including voltage source inverter (VSI), PLL, coupling inductance, LC filter as well as power, and current controllers is modeled. PI power and current controllers are optimally designed to improve the stability response of the grid connected microgrid. The power controller is designed to determine the reference current using the measured dq voltage and current while the minimizing of the error between the measured output and reference currents is the aiming of the current controller. The design of the power and current controller parameters as well as LC filter components and damping resistance is formulated as an optimization problem where particle swarm optimization is employed to solve the design problem. For dynamic enhancement of the grid connected microgrid, an objective function of the nonlinear time domain simulation is considered. The power exported response of the grid using the optimal parameters is checked using a step (up and down) change disturbance in the injected active and/or reactive powers. The effectiveness of the proposed approach for the microgrid stability enhancement is shown in the results.