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研究了交直流互联系统采用变结构控制策略提高系统的暂态稳定性问题。以一单机无穷大系统为研究对象，并以交直流互联系统的动力学方程、发电机的电磁功率方程和高压直流输电直流功率调制规律方程为基础，建立了发电机励磁与高压直流输电综合控制的非线性数学模型。采用滑膜变结构控制策略设计了发电机励磁和高压直流输电的综合控制器，该控制器采用先设定系统的滑模运动方程，再求取等效系统，最后求取切换面的方法来得到控制规律。在交流输电线路发生故障时，采用常规的控制策略和文章提出的控制策略对系统进行了仿真，仿真结果表明，采用该控制策略能够显著提高输电系统的暂态稳定极限及暂态稳定性。“,”To improve transient stability of AC-DC interconnected power system by variable structure control strategy, taking signle machine infinite bus system as research object and based on dynamical equation of AC-DC interconnected power system, electomagnetic power equation of generator and the equation for power modulation of HVDC transmission system, a nonliear mathematical model for comprehensive control for HVDC power transmission and generator excitation is built. A comprehensive controller for HVDC power transmission and generator excitation is designed by sliding mode variable structure control strategy. The control law for the designed controller is achieved by following procedures： firstly a slide mode motion equation for the control system is set; then an equivalent system is attained; finally the control law is obtained by solving the switching surface equation. The proposed control system is simulated by conventional control strategy and the proposed control strategy respectively, and simulation results show that both transient stability limit and transient stability of AC-DC interconnected power system can be evidently improved by use of the proposed control strategy while fault occurs in AC power transmission line.