Abstract:

As a power flow control device, Sen transformer changes the amplitude and phase of voltage and current at both ends of the access line through gear adjustment to achieve power flow regulation. However, due to its complex and compact wiring form and internal structure, Sen transformers have more complex fault characteristics than ordinary power transformers, which brings difficulties to their ontology protection configuration. In order to solve this problem, this paper analyzes the topology of Sen transformer and establishes a differential protection scheme based on physical principles such as Kirchhoff's current law and electromagnetic induction law. The scheme installs TA at the input end, output end of Sen transformer and the end section of the winding of the excitation unit, and by configuring the Sen transformer with balance differential protection and magnetic balance differential protection, it can reflect the turn-to-turn fault and turn-to-turn fault of each winding of Sen transformer, as well as the short circuit fault of the leads between the windings, which effectively solves the problem of difficult protection configuration for Sen transformer body. Finally, the PSCAD/EMTDC simulation platform is used to verify the feasibility of the proposed scheme, which provides a theoretical support for the subsequent in-depth research and engineering application of Sen transformer.

Key words: Sen transformer, magnetic balance differential protection, electric balance differential protection