The New Solid-state Current Limiter Control System Improvements

With the continuous expansion of power system's scale and capacity, short-circuit capacity becomes a significant constraint factor to the development of power system. Therefore, taking rapid measures to limit the short circuit current is required to reduce the damage to the power system which is caused by the short circuit fault. The traditional methods to limit the short circuit current have many shortcomings. So new current limiting technology turns into one of the hot research spots at home and abroad.Along with the development of power electronics technology, the Solid State Fault Current Limiter (SSFCL) has broad prospects for development. The new type SSFCL has many advantages such as a simple structure, flexible application, good current limiting performance and low wastage. On the basis of former research on the new type SSFCL, this paper further analyses and discusses the improvement on the control system and performance. Moreover, it dose preliminary study on the achievable structure and working principle of the current-limited United Power Flow Controller(UPFC),which is brought forward in the lab and simulates the operation as well.The first two chapters mainly introduce the background and research status of SSFCL, expatiate the topology and control strategy of the new type SSFCL, and briefly present the principle of the current-limited UPFC.The third chapter elaborates the improvement on the structure and the optimization performance of the 10kV/600A/10kA industrial prototype's control system developed on the laboratory. Meanwhile, it specifically introduces the realization and circuit design of the control system, which is controlling the alternation and isolation between the site monitoring and control module and the core monitoring platform through optical fiber. Finally the corresponding circuit board is built.The forth chapter briefly describes the structure and working principle of the current-limited UPFC. What's more, it also introduces the realization of specific functions and the switching between different operating modes when UPFC combines with the new type SSFCL. Based on the controlling method of cross decoupling the realization of UPFC's power flow control function is simulated and analyzed by the simulation tool in Matlab software.Finally, the paper summarized the work and the existing application problems of the new type SSFCL is analyzed.