跨大区互联电网与省级电网大扰动振荡耦合机制

Study on the Oscillation Coupling Mechanism Between Interconnected Power System and Provincial Power Grid

华北电网与华中电网特高压交流互联后,位于华中电网西部末端且与互联通道电气距离最远的四川电网,其网内枢纽电站及其出线故障将会引发特高压通道功率大幅涌动,并成为约束南北电力互济的重要因素之一。首先分析了华北—华中特高压互联电网网架拓扑结构与转动惯量分布特征;基于所定义的广义驱动能量,揭示华中不同省级电网故障扰动后,特高压通道华中侧落点电网的注入能量差异;通过理想主导振荡模态及大电网仿真轨迹分析,指出过渡期电网固有结构所决定的振荡机群同调性和振荡耦合叠加性,是导致四川网内故障激发大区振荡首摆驱动能量和反摆制动能量显著增大,进而引发特高压通道功率大幅涌动的根本原因。基于广义驱动能量的影响因素分析,提出相应的缓解措施。该研究可提升特高压大电网动态行为机制的认知能力和大电网安全稳定运行的驾驭能力。

After the interconnection of North China Power Grid （NCPG） and Central China Power Grid （CCPG） by UHVAC, a short-circuit fault of Sichuan network may trigger a substantial power surging through UHVAC channel and will restrict the transmission capacity. In this paper, the characteristics of network structure and rotational inertia distribution, were analyzed for CCPG firstly. Based on generalized driving energy, the divergence of power surge peak caused by faults happened at different provincial grids is revealed. By the ideal oscillation mode and grid simulation trajectory analysis, the paper points out that the two dominant oscillation frequency closing to 1：2 determined by the inherent structure of the UHVAC transition period is the primary cause for significant power surging of UHVAC channel. Furthermore, the influence factors of generalized driving energy are studied and corresponding mitigation measures are put forward. Conclusion drawn by this paper is important to enhance the cognitive abilities of the dynamic behavior and the control abilities of stable operation for UHVAC interconnected gird.