Robust Decentralised Voltage Control Strategy for DC Microgrids Considering Disturbances and Polytopic-Type Uncertainties

Abstract

Constant power loads (CPLs) may cause voltage oscillations or even endanger the stability of the entire DC microgrid systems due to their negative impedance characteristics. For this reason, this paper investigates the issue of DC microgrid voltage control in the presence of uncertain CPLs. A robust decentralised voltage controller for an autonomous DC microgrid is proposed in this paper. The proposed controller ensures the DC microgrid stability and furnishes the desired operation in the presence of different sources of uncertainty and disturbances. To that end, the polytopic state-space model of the system is developed. Then, an output feedback controller is designed to dynamically control the voltage of an autonomous DC microgrid. The main contributions of the proposed voltage controller can be highlighted as follows: The proposed controller is fully decentralised; it requires only voltage measurement and does not require additional state measurements or state estimators; due to the robust performance feature of the proposed approach, it does not require pre-filter design; the proposed linear matrix inequality condition is less conservative. All these, in turn, reduce the computational burden and complexity. Various scenarios have been conducted in MATLAB/Simscape Electrical Toolbox to investigate the effectiveness and efficiency of the proposed control framework.