Dynamic Simulation of Low-voltage Distribution Grid with Integration of Power Electronics coupled Loads and Generators

More and more active components, i.e. renewable generators, controllable loads, and storages, were integrated to low-voltage distribution grids. They were often interfaced with power electronics and their active participation in the power system may lead to voltage instabilities and power quality problems. Therefore, one research topic was to analyse the dynamic interactions between these active components, and to develop appropriate control architecture and techniques, which are able to avoid the corresponding instabilities and improve the power quality in the low voltage grids. One challenge of such dynamic simulation was to simulate the interacted system with time resolution of millisecond and to ensure the synchronization between them. In this paper, the suitable dynamic models of single-phase power electronic load and three-phase power electronic generator were conducted. These dynamic models were simulated and validated by the voltage-step-response, respectively. The voltage unbalance was used to quantify the interactions between the dynamic models and grid. In the steady state, the power electronic load induced less voltage unbalance comparing to the conventional passive load, because the power electronic load had better power factor. In certain dynamic processes, with the higher penetration of PE components in the LV grid, we observed the significant increase of voltage unbalance, which was induced by the interactions between the controllers of the active components. Such effects should be considered in the design of low-voltage gird system and its components.