Study On Small Signal Stability Of Power System Containing Flexible Devices

Flexible AC Transmission Systems (FACTS) compatible with the existing power system and can be achieved on flexible control, effectively solve the current problems of power system development bottlenecks. In recent years, the problems of Small Signal Stability about power system which containing FACTS devices has attracted increasing attention to electricity workers in countries, and more new research results are emerging. But most of these study are based on the expand Phillips-Heffron model, and the Phillips-Heffron model does not strictly consider the role of damper winding. Then the results of the analysis will inevitably be some deviation in some cases. Recently, although there have been more detailed visual linearized model of power system include FACTS devices, it is directly applied to the form of the expand Phillips-Heffron model and not perfect.Based on the linearized model considering the effect the damper windings (single-machine c₁～c₁₂ model, multi-machine c₁～c₁₈ model), the correspondingresearch about power system which containing FACTS devices have been done in this thesis. Main achievements are as follow:In this thesis, the linearized model of single-machine-SVC-TCSC-infinite-bus system is established with the effect of damper windings, namely extended c₁～c₁₂ model. Based on this model, the expression of the total damping torque of SVC and TCSC is given, and the relevant factors that affect the damping characteristics of SVC and TCSC are discussed. The research indicates: the damping effectiveness of SVC and TCSC will go up along with active load increasing. The damping effectiveness is weaker, when active load and damper gain of TCSC is low, but is positive. Moreover, the total damping of SVC and TCSC is closely with the line parameters, TCSC compensation degree and the controller parameters and so on. In order to get good control effect, they need coordinate and optimal design when SVC and TCSC are in Joint operationThe expand Phillips-Heffron model is established containing SVC and TCSC in the article. Based on this model and considering the generator parameters and the operating Conditions, there is such possibility: The damping effectiveness is negative, when active load and damper gain of TCSC is small, this is different from the result with extend c₁～c₁₂ model. In view of this, the in-depth research should be used detailed model to minimize bias in the future. For multi-machine power systems, extended c₁～c₁₈ model incorporating SVC and TCSC is established in this thesis. This model is more Flexibility and practicality compared to some of the existing model. Then, the promotion model of multi-machine system with more than one SVC and TCSC has been given. Finally, extended c₁～c₁₈ model has been used for small signal stability analysis. The results show that SVC and TCSC can effectively co-operation to enhance system stability in the multi-machine systems.