Study on the Organization Scheme and Voltage Sag Mechanism of PEDF Distribution System

Because of a high proportion of renewable energy sources (RESs) access, the establishment of a “photovoltaic, energy storage, DC, flexible” distribution system (PEDFDS) has great value, such as reducing power loss and saving construction costs. This paper investigates the organizational scheme of the PEDFDS and its voltage sag mechanism. First, the fundamental functions and control strategies of crucial components in the PEDFDS are elucidated. Then, the voltage sag mechanisms are studied by various transient disturbances, and the propagation characteristics of the voltage sags under different voltage levels are explored. Finally, a detailed simulation model of the PEDFDS is built in MATLAB/Simulink, and the goal is to analyze the voltage sag mechanisms caused by the instantaneous load change and single-pole grounding faults. From the simulation results, the voltage sag-blocking effect of the DC solid-state transformers (DCSSTs) can be confirmed, and the correctness of the theoretical analysis is verified.