考虑完整低电压穿越过程的SG-DFIG并联系统暂态同步稳定性分析
Transient Synchronization Stability Analysis of SG-DFIG Parallel System Considering Complete LVRT Processes
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中文总结 AI 辅助
研究考虑完整LVRT过程的SG-DFIG并联系统暂态同步稳定性，基于DFIG的LVRT划分暂态过程阶段并建模，推导GSE，提出改进等面积准则方法，为混合系统TSS机制提供清晰物理图景，紧密联系传统SG主导电力系统暂态稳定性。
中文摘要 AI 辅助
尽管已有大量工作致力于含可再生能源设备和同步发电机（SG）的混合系统暂态同步稳定性（TSS）的详细电磁暂态仿真，但考虑可再生能源设备完整低电压穿越（LVRT）过程的潜在机制仍有待研究。本文以SG与双馈感应发电机（SG-DFIG）并联系统为研究对象，基于DFIG的LVRT将其暂态过程分为四个阶段，建立描述完整4阶段LVRT过程的暂态模型。研究发现多数故障会使DFIG进入LVRT并使并联系统呈现顺序切换特性，推导了不同阶段的统一广义摇摆方程（GSE），并提出考虑频率跳变和非线性阻尼的改进等面积准则方法评估TSS，理论分析结果得到硬件在环实验和仿真支持。
英文摘要
Although a large amount of work has been devoted to detailed electromagnetic transient simulation in analyzing transient synchronization stability (TSS) of hybrid systems containing renewable energy equipment and synchronous generator (SG), the underlying mechanism considering complete low-voltage ride-through (LVRT) processes of renewable energy equipment remains to be studied. Taking the SG and doubly fed induction generator (SG-DFIG) parallel system as an objective, this work divides its transient processes into four different stages: pre-fault (stage 1), during-fault (stage 2), early post-fault (stage 3), and late post-fault (stage 4), based on the LVRT of the DFIG, and establishes a transient model to describe the complete 4-stage LVRT processes. By studying the condition for entering the LVRT, it is found that vast majority of faults can cause the DFIG to enter the LVRT and make the parallel system exhibit the sequential switching characteristics. Similar to the SG-SG parallel system, which can be reduced to a single SG and described by a second-order swing equation, a unified generalized swing equation (GSE) under different parameters for different stages 1, 2, and 3 is derived. Therefore, the transient stability of the parallel system can be dealt with easily, and further, an improved equal area criterion method considering two additional effects of frequency jump and nonlinear damping is proposed to evaluate the TSS. These GSE-based theoretical analysis results are all supported by extensive hardware-in-the-loop experiments and simulations. Obviously, this work provides a clearer physical picture for the TSS mechanism of the hybrid system considering complete LVRT processes, and makes a closer connection with the transient stability of traditional power systems dominated by SG.
