An Adaptive Control Strategy for Energy Storage Interface Converter Based on Analogous Virtual Synchronous Generator

Abstract

In the DC microgrid, the lack of inertia and damping in power electronic converters results in poor stability of DC bus voltage and low inertia of the DC microgrid during fluctuations in load and photovoltaic power. To address this issue, the application of a virtual synchronous generator (VSG) in grid-connected inverters control is referenced and proposes a control strategy called the analogous virtual synchronous generator (AVSG) control strategy for the interface DC/DC converter of the battery in the microgrid. Besides, a flexible parameter adaptive control method is introduced to further enhance the inertial behavior of the AVSG control. Firstly, a theoretical analysis is conducted on the various components of the DC microgrid, the structure of analogous virtual synchronous generator, and the control structure's main parameters related to the DC microgrid's inertial behavior. Secondly, the voltage change rate tracking coefficient is introduced to adjust the change of the virtual capacitance and damping coefficient flexibility, which further strengthens the inertia trend of the DC microgrid. Additionally, a small-signal modeling approach is used to analyze the approximate range of the AVSG's main parameters ensuring system stability. Finally, conduct a simulation analysis by building the model of the DC microgrid system with photovoltaic (PV) and battery energy storage (BES) in MATLAB/Simulink. Simulation results from different scenarios have verified that the AVSG control introduces fixed inertia and damping into the droop control of the battery, resulting in a certain level of inertia enhancement. Furthermore, the additional adaptive control strategy built upon the AVSG control provides better and flexible inertial support for the DC microgrid, further enhances the stability of the DC bus voltage, and has a more positive impact on the battery performance.