TY - JOUR
T1 - A Modular Adaptive Robust Nonlinear Control for Resilient Integration of VSIs into Emerging Modernized Microgrids
AU - Davari, Masoud
AU - Aghababa, Mohammad Pourmahmood
AU - Blaabjerg, Frede
AU - Saif, Mehrdad
PY - 2021/6
Y1 - 2021/6
N2 - 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.
AB - 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.
KW - Disturbance observer
KW - emerging grids
KW - grid-connected voltage-source inverters (GC-VSIs)
KW - Lyapunov Stability
KW - mismatched disturbances
KW - multi-terminal ac/dc (MIACDC) grids
KW - phase-locked loop (PLL)
KW - sliding mode control (SMC)
KW - uncertainties
U2 - 10.1109/JESTPE.2020.2984231
DO - 10.1109/JESTPE.2020.2984231
M3 - Journal article
VL - 9
SP - 2907
EP - 2925
JO - I E E E Journal of Emerging and Selected Topics in Power Electronics
JF - I E E E Journal of Emerging and Selected Topics in Power Electronics
SN - 2168-6777
IS - 3
M1 - 9050724
ER -