| The unified power flow controller(UPFC) is one of the flexible AC transmission systems(FACTS) which can control power-system parameters such as terminal voltage,line impedance and phase angle to control power. flow,voltage,transient stability,damping oscillation etc.The UPFC is a multiple functional FACTS,so as its concept had been just put forward it attracted a growing interest in studying .The dissertation regarded studying the dynamic characteristic of UPFC as the main goal,it developed the research in three aspects: mathematical model,the reciprocity of internal controllers and the ability to damp system oscillations.First the dissertation summarized the research on current situation of UPFC and FACTS and its application situation in the project,and also introduced the research background of this subject.Then set up the dynamic model and power flow model of UPFC that can reduce the reciprocity of internal controllers of single UPFC.Put forward the control strategy of UPFC internal controllers,and proposed holding the active power P_b as the standard to minimize the mutual influence between controllers. Have derived the mathematical model of the single machine infinite bus power system installed with an UPFC. Designed the controller within UPFC and carried on simulation analysis at the same time, the result indicated that there is negative interaction among UPFC different controllers.In order to find the reason that caused the reciprocity among different channels,the paper proposed a criterion of judging and proved it with simulation analysis.Set up the Phillips-Heffron model of the single machine infinite bus power system installed with an UPFC, Utilize damping torque analysis analyzed mechanism of damping torque that UPFC offered to system,and used the phase compensation method to design the UPFC damping controllers. The result show that the UPFC damping controller designed either had fine and robust effect in single machine infinite bus or four machine two regional systems. |
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