Simulation of voltage control processes in low-voltage microgrid nodes with renewable energy sources and energy storage system

Introduction. The development of low-voltage microgrids (LV MG) with renewable energy sources requires effective control of their operating parameters, in particular voltage. The problem of voltage control in MG is exacerbated by the practical use of remote control systems for grid-forming inverters (GFIs) under conditions of limited data transmission speed. Goal. Identification of the features of local voltage control in LV MG nodes connected to distribution systems using reactive power of GFIs, in particular to assess the dependence of the droop-control coefficient on network parameters and to determine quasi-stationary time intervals. Methodology. The study was carried out using a newly developed imitation model in the PowerDynamics.jl environment for analyzing the dynamics of LV MGs, which are characterized by predominantly active feeder resistance and take into account the specific operating features of GFIs. Results. It has been established that the operating modes of LV MG connected to the distribution system can be considered quasi-stationary over intervals longer than 60 s, which allows the use of static control characteristics without taking into account fast transient processes. The operation of the model was analyzed under conditions of reactive power reduction at the MG input using a PI controller and maintaining a specified value of GFI reactive power. Scientific novelty. A new computational model has been developed which, unlike existing ones, enables comparison of different methods of reactive power distributing among a group of distributed energy sources and investigation of the features of voltage regulation using GFIs. Practical value. Using the developed model, an analysis was performed and the dependence of the voltage droop-control coefficient on the GFI reactive power was determined. Quasi-stationary intervals for power and voltage in LV MGs were established. The developed model confirms the effectiveness of voltage control through GFI reactive power in different MG operating modes. Practical recommendations for setting GFI parameters and information transfer speed in LV MG control systems were formed. References 56, tables 2, figures 7.