Research on the Impact of the Interaction Between Renewable Energy and Loads on the Voltage Characteristics of Receiving-End Grids and Control Strategies

As large-scale renewable energy sources are integrated into the receiving-end grid, their interaction with load demands careful examination. This paper begins by analyzing the characteristics of active and reactive power fluctuations in renewable energy sources during low-voltage ride-through (LVRT). For a typical single-machine system connected to the grid, the mathematical relationship between the output power of renewable energy sources and the voltage at the point of common coupling is derived, determining the operating range without entering the LVRT state. By incorporating load models into the mathematical analysis, it is shown that the correlation between active power and voltage varies according to the load proportion. This leads to the identification of two types of “repeated LVRT” mechanisms dominated by either active or reactive power. Furthermore, considering the dynamic load model, motor slip is shown to affect the stable operating range of renewable energy sources, contributing to LVRT phenomena. Finally, from the perspective of the relationship between the operating point of renewable energy and the LVRT threshold curve, optimization strategies are proposed to address several types of new voltage stability issues caused by the interaction of various loads. The feasibility of these voltage phenomena and control strategies is validated using a simulated model.