Investigation of active voltage support control approach of DC distribution networks based on virtual inertia coordination

DC distribution networks (DCDNs) possess the advantages of high power efficiency, low operation loss, and favourable control flexibility, and are regarded as an essential form of future power distribution systems. In order to increase the voltage transient performance of DCDNs against disturbances, this paper proposes a methodology for realising the active voltage support control of DCDNs based on virtual inertia coordination. Firstly, the impact of the inertia of DCDNs towards the transient voltage change is analysed, and the active voltage support mechanism considering the variable droop inertia control and virtual DC motor inertia (VDCMI) control is explored. Then, a time sequence coordination strategy based on the voltage grading of DCDNs is developed, and an adaptive inertia coefficient is designed to achieve the inertia adjustment in terms of the voltage sag and recovery processes. Using MATLAB/Simulink, a detailed model of the double-terminal DCDNs is created to check the efficacy of the proposed approach. Different voltage disturbance scenarios are imitated, and the comparative simulations demonstrate that the proposed approach can fully utilise the inertia potential of the DCDNs to suppress the voltage sag and smooth the voltage recovery procedure. The proposed method's validity and feasibility can be well validated.