Small-Signal Stability Analysis of Grid-connected Converters with Different Reactive Power Control

Renewable energy Grid-Connected systems are confronted with complex stability issues. Meanwhile, the diversification of control strategies further increases the difficulty of stability analysis. Grid-connected converters have various reactive power control (RPC) methods, which are summarized as constant voltage control (CVC), constant reactive power control (CRPC), and reactive power-voltage droop control (QVC) in this paper. To explore the impact of the aforementioned three different RPC methods on system stability, this paper establishes a small-signal model of the system under different control methods and analyzes its smallsignal stability using the state space analysis method. During the analysis, it is acknowledged that the impact of phase-locked loops (PLL) on stability has been researched. Thus, in this paper, we further simplify the complex system by neglecting the dynamic effects of the PLL, focusing instead on the selection of RPC methods and the setting of control parameters and their influence on system stability. This work provides a framework for stability analysis, control structure selection, and parameter design of grid-connected converters. The validity of the work presented is confirmed through simulations in DlgSILENT PowerFactory.