Research On UPFC And Its Application In Improving The Available Transfer Capability Of Transmission Line

As the national modernization developing, electricity consumption of industry and civilianis growing fast, so does the total installed capacity. Because the cost of building new powerplant and transmission line is high, the focus of modern power system is how to improveavailable transfer capacity (ATC) and control system flow reasonable under the existing system.This paper design control strategies through analyzing UPFC and factors limiting ATC.The basic structure and operating principle of UPFC is analyzed by this paper firstly, andthe mathematical model under steady-state and transient is obtained. There’re four basic controlmethods for UPFC to change the load flow by adjusting all parameters of transmission line. Theanalysis and designs of series and shunt control systems are done to ensure the stable operationof UPFC, so does the power coordination design. In chapter four, factors of limiting ATC isanalyzed, and the improving methods are given. According to different factors of limiting ATC,pertinence control strategies of UPFC are designed.Control strategies are tested and verified in chapter five. The factors of limiting ATC arefound by analyzing system operation state after calculating load flow distribution of IEEE30-bus system by P-Q decomposition, and the access point and relative control strategy aredetermined. Then, simulation model is built in MATLAB/Simulink to verify that UPFC canadjust the load flow distribution and stabilize the system voltage by adopting appropriatecontrol strategies, thereby it can improve transmission line ATC in the running state.