Finite-Time Large Signal Stabilization for High Power DC Microgrids With Exact Offsetting of Destabilizing Effects

Abstract

The interleaved dual boost converter (IDBC) is a promising topology to interface high power solar photovoltaic (PV) generation or energy storage systems to dc microgrids (MGs). It provides a high boost ratio for voltage transformations and helps significantly to reduce ripples in the currents drawn from dc sources. However, the conventional control methods of IDBC cannot guarantee system stability in the presence of tightly regulated and rapidly varying power electronic loads which behave as constant power loads (CPLs). Moreover, the uncertainties of converter systems may further affect the stability of MGs. In this context, a large signal stabilization scheme, which comprises finite-time observers (FTOs) and a finite-time controller (FTC), is proposed. By considering CPLs and parameter dispersions as system disturbances, FTOs are able precisely observe the disturbances in finite time. Then the FTC exactly offsets the estimated values and stabilizes all system states at their designated points in finite time. By doing so, the finite-time large signal stability can be obtained and the corresponding results are proved with Lyapunov theorems. A detailed control parameter selection guideline is provided for practical applications. Simulations show that the proposed method gives a wider stability margin than the conventional PI (proportional-integral) control. Furthermore, experiments verify its effectiveness and feasibility.