A Modular Adaptive Robust Nonlinear Control for Resilient Integration of VSIs into Emerging Modernized Microgrids
IEEE Journal of Emerging and Selected Topics in Power Electronics
And uncertainties, disturbance observer, emerging grids, grid-connected voltage-source inverters (GC-VSIs), Lyapunov stability, mismatched disturbances, multi-infeed ac/dc (MIACDC) grids, phase-locked loop (PLL), sliding mode control (SMC)
Nowadays, emerging modernized microgrids (MMGs) have significantly employed the voltage-source inverters (VSIs). VSIs are enabling technologies to form multi-infeed ac/dc (MIACDC) power systems integrating a variety of generation units and different loads into one coherent grid. In emerging MMGs, the frequency-dependent dynamics of multiple components affect the PQ-controlled, grid-connected VSIs (GC-VSIs), particularly when integrated into a weak network. In order to address this challenging problem, the full integration of the dynamics of the phase-locked loop (PLL) into those of GC-VSIs is accomplished in this research via an innovative modular structure to improve the VSI's performance. This action is expected to significantly reduce the effect of the ac-side dynamics on the control of GC-VSIs. In addition, there are uncertainties associated with the parameters in the system. Accordingly, mismatched disturbances and uncertainties (both matched and mismatched ones) will appear in a nonlinear dynamic problem, and therefore, from the standpoint of control theories, mismatched disturbances and uncertainties should be overcome. Satisfying them is a difficult task in control of nonlinear systems. Therefore, one of the main contributions of this work is finding an appropriate mathematical model of GC-VSIs in the dq -frame for the problem under study. Afterward, in order to control both active and reactive power independently, this article presents a novel two-degree-of-freedom (2DoF) methodology with an enhanced modular design. It combines the sliding-mode control with a 'new sliding manifold' and a disturbance observer with a 'new adaptation rule' taking care of uncertainties and mismatched disturbances. Those disturbance signals may be generated by the PLL dynamics or voltage signals affecting the GC-VSI's dynamics. Through providing mathe- matical analyses (including stability assessments via various theorems using Lyapunov stability criterion), simulation results, and experiments, this article demonstrates the effectiveness of the proposed control methodology. The industrially accepted GC-VSI equipped with an LCL -filter is used here.
Davari, Masoud; Aghababa, Mohammad Pourmahmood; Blaabjerg, Frede; and Saif, Mehrdad. (2021). A Modular Adaptive Robust Nonlinear Control for Resilient Integration of VSIs into Emerging Modernized Microgrids. IEEE Journal of Emerging and Selected Topics in Power Electronics, 9 (3), 2907-2925.