Transient Stability Analysis Of Power System With TCSC

With the persistent increasing power demand and the stress of the grid in these decades,the problem of power system stability emerges prominent.The occurance of several systematic contingencies due to transient failure suggest it expedient to find measures to improve the stability.To implement bulk power transmission over large distance and the new resource grid-connection,the flexible AC transmission system(FACTS)elements based on the power electronic technology,such as the thyristor controlled series compensator(TCSC),is finding more applications and presents a challenge for transient stability analysis.The TCSC uses thyristors to control the AC line impedance continuously within a relatively large range.It has found wide applications and is one of the most successful FACTS.It can promote the transmission capacity of the corridor,dampen the power oscillations,and improve the transient stability.In the research of the dynamic behavior of TCSC and its impact on the power system,there are mainly two kinds of methods:the time domain simulation and the direct method,but these two methods have many difficulties,such as accurate modeling of time domain modell,effective simulation method and construction of energy function needs to be further research.The main work of this paper is as follows:(1)Establishing the mathematical model of the power system with TCSC,which includes the generator,load,network structure preserving model and the TCSC control model.(2)Considering the single-machine infinite-bus system and the multi-machine system,the power flow calculation and time domain simulation of power system with TCSC are implemented.(3)The energy function construction of power system with TCSC based on network structure preserving model is described in this paper.Introduces the methods and steps of constructing the energy function,and prove that the monotonic decreasing of the energy function for the power system with the static TCSC model.The energy function of single-machine infinite-bus system and multi-machine system considering dynamic TCSC model is calculated and is verified by the non positive characteristic of the time derivative.The calculation results show that,TCSC can suppress the system oscillation and improve the transient stability of the system.The energy function considering the static characteristics of TCSC proposed by this paper meets the requirements for a qualified energy function.The transient stability analysis of the TCSC dynamic energy function method is still needed to be further studied.