Dynamic Compensation Control Strategy of DC Microgrid Bus Voltage Based on Disturbance Observer

Abstract

To solve the problem of bus voltage dynamic response under the droop control method in DC microgrid, a parallel dynamic compensation structure of converter based on disturbance observer was proposed. Firstly, the problems existing under the traditional DC droop control are analyzed. The state space model is established for the parallel models of multiple converters in the DC microgrid. The current changes caused by the common load switching in the parallel state are analyzed. The synchronous measurement method (PMU) is applied to the disturbance current. The measurement distribution is carried out. According to the left and right mutual decomposition theory and the Youla parameterized stability controller theory, the parallel dynamic compensation structure of the converter based on the disturbance observer is obtained. The model matching algorithm is used to obtain the Youla parameterization matrix Q(s). The current loop compensation structure M(s) is designed to counteract the effect of the compensation signal on the current loop. Simulation results show that the structure can accelerate the dynamic response speed of DC bus voltage when the common load is switched. At the same time, the structure can suppress the double frequency disturbance of DC bus voltage caused by an unbalanced load and keep the bus voltage stable.