改善暂态稳定性的HVDC非线性控制策略

提出了一种新的高压直流输电系统的非线性紧急控制策略。首先建立包括HVDC联络线在内的交、直流互联电网的观测解耦状态空间模型，根据该模型，只需要当地信号实施控制, 驱动子系统到达局部平衡点，就能使全系统达到稳定，然后应用非线性最优变目标控制策略推导出HVDC系统的控制规律。用3机系统进行数字仿真的结果表明，该方法能够在大干扰和紧急状态下充分利用HVDC的快速响应和短时过载能力，提高交、直流互联系统的暂态稳定性和对功率突然严重缺额的地区进行紧急功率支援。

A NONLINEAR CONTROL STRATEGY OF HVDC FOR IMPROVING TRANSIENT STABILITY OF POWER SYSTEMS

A novel nonlinear emergency control method of transmission systems is presented in this paper. First, an observation decoupled state space model of AC and DC interconnected power systems is developed. Based on this model, local information is only needed to drive the subsystems of a system to reach their local equilibrium points, and then the total system is stable. Then the nonlinear control rule of HVDC links is derived using optimal-variable-aim strategy (OVAS). The simulation results of a three machines system show that the proposed method can make good use of the fast response and short-time over load capability of HVDC links to improve the transient stability of interconnected systems, or to support emergent power to the districts suddenly seriously short of power. This project is supported by National Key Basic Research Special Fund of China (No. G1998020311).