title: Method to eliminate flux linkage DC component in load transformer for static transfer switch.
abstract: Many industrial and commercial sensitive loads are subject to the voltage sags and interruptions. The static transfer switch (STS) based on the thyristors is applied to improve the power quality and reliability. However, the transfer will result in severe inrush current in the load transformer, because of the DC component in the magnetic flux generated in the transfer process. The inrush current which is always 2 ~ 30 p.u. can cause the disoperation of relay protective devices and bring potential damage to the transformer. The way to eliminate the DC component is to transfer the related phases when the residual flux linkage of the load transformer and the prospective flux linkage of the alternate source are equal. This paper analyzes how the flux linkage of each winding in the load transformer changes in the transfer process. Based on the residual flux linkage when the preferred source is completely disconnected, the method to calculate the proper time point to close each phase of the alternate source is developed. Simulation and laboratory experiments results are presented to show the effectiveness of the transfer method.
authors.affiliation: State Key Laboratory of Advanced Electromagnetic and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Yu
authors.identifier: 0000-0003-4864-9952
authors.initials: Y
authors.lastname: He
authors.affiliation: State Key Laboratory of Advanced Electromagnetic and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Chengxiong
authors.identifier: 0000-0002-0482-8783
authors.initials: C
authors.lastname: Mao
authors.affiliation: State Key Laboratory of Advanced Electromagnetic and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Jiming
authors.identifier: 0000-0002-0853-7385
authors.initials: J
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Advanced Electromagnetic and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Dan
authors.identifier: 0000-0002-6440-8529
authors.initials: D
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Advanced Electromagnetic and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Bing
authors.identifier: 0000-0002-7322-465X
authors.initials: B
authors.lastname: Tian
mesh_terms: D004581:Electronics / Q000295:instrumentation / Q000379:methods*