Research Of The Coupling Transformer In The Solid State Fault Current Limiter System

With the development of the society, the demand of the electrical energy isgrowing fast and the power system is gradually expanding. As a result,the rapidlyincreasing level of the short-curcuit current threats to the power network security andstability operation.In the recent years,many countries from all of the world put in a lotof manpower and resources to research the technology of short-circuit current limitingand FCL development.Zhejiang University has been in-depth study on the currentlimiter applicable to the AC power system and has won a number of patents andself-owned intellectual property rights since the research of the solid short-circuitcurrent limiter in the last century mid-1990s that has been nearly a decade history.However, a large number of short-circuit fault current limiters are still in theexperimental and testing stage.And the great weight, large volume and high cost ofthe current-limiting equipments become the main obstacles of the FCL application.This paper, according to the special bridge-type SSFCL's requirements to the couplingtransformer,proposes a field-circuit coupling method that analyses the couplingtransformer's operational characteristics to reduce the weight, volume and cost of theFCL devices and make the short-circuit current limiter technology to application.Chapter 1 summarizes the power system's development status and the powernetwork's demand to the short-circuit current limite.At the same time,based on theextensive literature,chapter 1 intoduces the present short-circuit current limitingtechnology.Chapter 2 introduces the new type SSFCL's research status mainly, and thendetails the working principle and the topology of SSFCL.At last,chapter 2 studies thesaturated coupling transformer's operation state in the power network.Chapter 3 is based on the chapter 2.It mainly analyses the on-line transformer'selectromagnetic properties and establishes the corresponding mathematicalmodel.Meanwhile,chapter 3 analyses the transformer's operation state with FEA.Thispaper proposes the field-circuit coupling method that analyses the transformer'scharacteristic and uses the energy perturbation method to calculate transformer'sequivalent inductance.Finally, in the last section of this chapter, the design requirementis fixed on through test analyses.Chapter 4 uses the Ansys to simulate the whole SSFCL system and the chapter 5uses the Matlab to simulate the whole SSFCL system.At last,in the chapter 6,theremakes the research summarization and proposes the problom that has not beensolved,and meanwhile proposes the direction in the future.