中文摘要：

目前针对电压源型高压直流输电（VSC-HVDC）系统控制特性的研究仅限于联接到等值交流系统的情形,建立VSC-HVDC系统联接到含惯量的交流系统的模型,研究弱系统条件下交流系统内部参数与VSC-HVDC系统的相互作用有重要意义。利用同步发电机（SG）模拟含惯量的交流系统,首先建立了连接到SG的VSC-HVDC系统的小信号模型,并验证了模型建立的正确性;利用参与因子法分析了特征根与状态变量的关联程度。采用特征根分析和仿真验证结合的方法,分别研究了线路阻抗、SG的惯性常数、阻尼系数的参数变化对系统特征根的影响规律;最后研究了VSC控制器参数对系统稳定性的影响作用。结果和结论证明,系统小信号稳定性随着系统线路阻抗角减小、短路比（SCR）的降低而降低;当惯性常数取值〉1.2 s时系统小信号稳定性先增强后减弱但不会失稳,当阻尼系数D在0~0.5范围内变化时,系统小信号稳定性先增强后减弱,VSC控制器参数对系统小信号稳定性影响也较大,在一定范围内调整SG惯性常数、阻尼系数和VSC控制器内外环参数值可以提高系统小信号稳定性。

英文摘要：

Research on control characteristics of voltage source converter--high voltage direct current （VSC-HVDC） system is currently limited to the connection to the equivalent AC grid, thus, the model of VSC system connected to AC system with inertia should be established, and the analysis on interaction between internal characteristics of AC system and VSC is of important significance. Firstly, we used a synchronous generator （SG） to simulate the AC system with inertia so as to propose a small signal model of VSC system connected to synchronous generator, and verified the validity of the established model. Secondly, we analyzed the degree of correlation between eigenvalues and state variables with par- ticipation factor method. Thirdly, combining with eigenvalue analysis and simulation, we studied the influences of parameters on the characteristic roots of the system, respectively, such as the transmission line, inertia constant of syn- chronous generator, and damping coefficient. Finally, we analyzed the influences of VSC controller parameters on the stability of the system. The results have proved that the small signal stability of the system will decrease with the decrease of short circuit ratio（SCR） and the decrease of impedance angle of line. When the inertia constant is greater than 1.2 s, the small signal stability of system will enhance and then decrease but will not lose stability. When thedamping coefficient of SG ranges from 0-0.5 pu, the small signal stability of system will enhance and then decrease, and the controller parameters also affect the small signal stability of system, so stability will be optimized by adjusting these types of parameters within limits.