Research On Application Of New Bridge Type High-Tc Superconducting Fault Current Limiter

The short-circuit capacity of power grid and the magnitude of short-circuit current increase continuously with the growth of power system's capacity. Short-circuit current will directly influence the choice of electric equipments and stable operation of power grid. There are great demerits in traditional short-circuit limiters, and it is an urgent task for us to design new current limiting schemes and devices.In this paper, the history and recent development of high-Tc Superconducting Fault Current Limiter (SFCL) are firstly overviewed. Based on the classification, working principle and characteristics of several typical limiters are introduced. Research situations of bridge type SFCL are particularly generalized.Common bridge type SFCL could not limit the steady-state value of the short-circuit current. In order to solve this problem, new bridge type SFCL with a demagnetize loop is studied. Its limiting theory is made in-depth research. Simulation results prove that the peak and steady-value of short-circuit current can be well limited by this type SFCL. Then simulations further discuss the impact of three key parameters on limiting effect. This settles a theoretical foundation for choosing parameters in practical application.Control strategy of the new bridge type SFCL is studied for the control system's designing. Limiter's feedback signals are choosed. These control feedback signals are made numerical treatment by different method. According to changing characteristics of these feedback quantities in the short-circuit process, two comparison control algorithms are designed. In practice, we can choose control algorithm for different precision requirment.The new bridge type SFCL is combined with the distribution network of Tianjin Pipe Corporation. After choosing reasonable short-circuit occurring time, a variety of short-circuit faults in the system are analyzed by computer simulation software. Compared with normal bridge type SFCL, new bridge type SFCL's respond for double fault is studied. The simulation results demonstrate that the new bridge type SFCL has good limiting effect and response ability for single fault and double fault in distribution network system. And the bus voltage drop can also be well limited by it.For power semiconductor devices, there may be voltage, current capacity constraints in high voltage transmission and distribution network. Combined with practical example, overvoltage and overcurrent protections of power devices are preliminarily discussed. Then series-parallel circuits are theoretical designed for power devices.The actual application of new bridge type SFCL is promoted.In this paper, the application of a new bridge type SFCL is studied. The research has laid a theoretical foundation for its device. With the development of high-Tc superconduting technology and power electronics technology, high-Tc SFCL will be more extensive.