中文摘要：

针对某些情况下互联电网边缘地区故障会导致特高压联络线功率振荡甚至失稳解列的现象,将电力系统描述为端口互联结构,引入端口供给能量概念分析系统中各端口之间的能量流动。基于端口供给能量的分配定义支路暂态能量概念,推导出端口供给能量分配与线路电抗成反比,支路暂态能量大小与联络线功率振幅成正比的规律。对华中华北互联电网的仿真验证了上述规律,并在此基础上解释了扰动冲击在电网中传播进而影响系统稳定性的机理：由于发电和负荷比例悬殊,故障后产生的大量暂态能量难以就地耗散;又因为特高压联络线阻抗较小,暂态能量主要通过特高压联络线向周边区域转移,造成特高压联络线较其他超高压线路功率振荡幅度更大。仿真分析结果表明,利用所提出的端口供给能量方法能够清晰地阐述故障后系统中暂态能量的产生和流动过程以及特高压电网扰动冲击传播机理。

英文摘要：

It is found that some faults in distant area may cause power oscillations on the ultra-high voltage（UHV） tie-line and result in instability and separation under some circumstances. To elucidate the mechanism of the phenomenon, we described the power system as the port-based interconnected structure, and introduced concept of energy supply on port（ESP） and analyzed the energy flow between the ports. Based on the distribution of ESP, the concept of branch transient energy is defined. Furthermore, we deduced that the distribution of ESP is inversely proportional to the reactance of tie-lines and the quantity of branch transient energy is in proportion to the power amplitude of tie-lines. Simulations on the Central China and North China interconnected power grid are carried out to verify the above fules. On the basis, disturbance impact propagation mechanism on power system transient stability is explained as follows. Large amount of transient energy after disturbance cannot dissipate locally because of the disparity between generation and load, moreover, due to the small reactance of the UHV tie line, the transient energy transfers to the surrounding area mainly through the UHV tie line, which results in large power oscillations on the UHV tie line. Simulation and analysis results indicate that transient energy generation and flow and disturbance impact propagation mechanism on ultra-high voltage power system can be described by the proposed methodology of ESP.