Decentralized Dynamic Disturbance Compensation Control Strategy for Multiple Parallel Inverters in Microgrid

In order to enhance the anti-disturbance capability of voltage fluctuation, circulating current, harmonics and three-phase unbalance during microgrid island operation, a decentralized dynamic disturbance compensation control strategy for multiple inverters in parallel based on robust residual generator was proposed. First, considering the circulating current effect of parallel inverters, a parallel state space model of multiple inverters with line parameters under quasi-stationary line conditions was established, on the basis of droop control, the voltage fluctuation, circulation, harmonic, three-phase unbalance and power fluctuation were analyzed based on the inverter model. Secondly, for the double closed loop control structure of the inverter, a dynamic compensation controller Q(s) was designed from the perspective of disturbance cancellation, and its control signal was applied to the input terminal of the current loop to realize superposition with the original system current given signal, so as to achieve the effect of joint compensation for disturbance signals. This method simplified the structure of the current loop secondary dynamic compensation control, and realized the low-order theoretical derivation of Q(s). Then, a robust residual generator and a dynamic compensation controller Qi(s) were added to each parallel inverter, and the parameter expression of Qi(s) was derived based on local information to realize mutual influence among multiple inverters further decoupling. Finally, hardware-in-the-loop experiment on three inverters in parallel were designed on the RTDS platform to verify the effectiveness of the proposed strategy. © 2021 Chin. Soc. for Elec. Eng.