由直流输电引起的次同步振荡的阻尼特性分析

直流输电系统在次同步频率范围内的数学模型较难获得，这使得采用解析方法计算系统阻尼变得十分困难。文中采用时域仿真实现的复转矩系数一测试信号法，对直流输电系统的次同步振荡问题进行研究，通过频率扫描计算出了发电机组在次同步频率范围内的电气阻尼特性曲线，并同时考察了机组耦合程度、直流功率水平、触发角以及控制器参数等因素对电气阻尼的影响。还分析了直流输电换流器逆变运行时对附近发电机组次同步振荡阻尼的影响。表明由直流输电引起的次同步振荡问题只需要考虑整流站附近的发电机组，而不必考虑逆变站附近的发电机组。

DAMPING ANALYSIS OF SUBSYNCHRONOUS OSCILLATION CAUSED BY HVDC

In the subsynchronous frequency range, the difficulties in modeling HVDC converters make it almost impossible to calculate the system damping by an analytical method. In this paper the complex torque coefficient method realized by time domain simulation-the test signal method, is adopted to study the stability of SSO caused by HVDC systems. A series of test signals spanning the subsynchronous frequency range are injected to the studied unit to calculate its electrical damping in the subsynchronous frequency range. The impacts of the unit interaction factor (UIF), the DC power level, the firing delay angle and the parameter settings of the HVDC controller on the electrical damping of a unit adjacent to a rectifier are systematically studied. The electrical damping characteristics under inverter operation are also studied. It shows that the units adjacent to the inverter have no potential SSO danger.