The Research On Influence Of SFCL On Power System Transient Stability

With the rapid development of the power system, capacity of short-circuit and short-circuit current level is also rising. Traditional measures to limit short-circuit current has been unable to effectively deal with the increasing short-circuit current. Special current-limiting device conbined with the superconducting technology (superconducting fault current limiter) is self-examination, self-riggered and self-operation, can effectively limit the short circuit current and reduce the design capacity of various electrical equipment in power system, which has a very wide range of applications.Firstly, this paper summarizes the existing current limiting technology and research status of superconducting fault current limiter, introduces the basic properties of superconducting materials and basic working principle and topological structure of some commonly-used SFCL. Their characteristics including advantages and disadvantages are compared. Mathematical models of typical limiters such as the resistive-type and the brigde-type SFCL are introduced.After that we introduce the basic working principle and topological structure of core controlled fault current limiting device with series compensation. The influence of air gap on FCL is analyzed. DC control system and test system of FCL are designed to test the performance of short ciruit current limit and series compensation.Finally, based on a single-infinite model system, the transient stability due to introduction of SFCL has been analyzed. The impact of limiting impedance to the transient process and transient stability of the single machine infinite bus system is discussed. Then take induction machine connected to simplified system with FCL for example, the faulted network is simplified according to Thevenin’s theorem and the mathematical equation of the Thevenin voltage is derived when resistive-type FCL or SICSFCL is used. The transient process of induction machine is analyzed in detail. A power system model is built to verify the impact of R-type SFCL and L-type SFCL to transient stability of single-infinite model system or induction machine simulated by PSCAD/EMTDC software.