A High-Voltage “Sen” Transformer: Configuration, Principles, and Applications

Abstract

As is well known, the high installation and operational costs of the unified power flow controller (UPFC) restrict its widespread applications in power grid. An economical "Sen" transformer (ST) that is composed of a three-phase four-winding transformer and three sets of tap changers provides similar power flow control functionality as the UPFC. Unfortunately, the ST is not suitable for high-voltage systems because of its high-voltage insulation requirement on all secondary windings and tap changers. To overcome this problem, a high-voltage "Sen" transformer that consists of a three-phase two-winding transformer and two sets of tap changers is proposed in this paper. In high-voltage power system applications, the high-voltage "Sen" transformer (HVST) offers several advantages over the ST, such as fewer windings, fewer tap changers, bigger phase-shift range, and larger power flow control region. This paper focuses on the configuration, principles, and applications of the HVST. The contrastive simulation results in a two-area test system and an IEEE 39 bus system prove the validity and advantages of the proposed HVST. Moreover, a 10 kV HVST device and a corresponding experiment platform are developed to verify the feasibility and effectiveness of the HVST. The HVST can provide a flexible voltage and power flow control.

A Comprehensive Review of Power Flow Controllers in Interconnected Power System Networks

“…The ST deals with the full rated voltage and full fault current. The cost of insulation and machining difficulty will considerably increase when it is used for the EHV and UHV grids [91], [92]. Also, it is challenging to handle system imbalances.…”

Performance Evaluation and Reliability of Flexible Asynchronous AC Link and LCC–HVDC Link Under Fault Conditions

“…The ST uses a three-phase four-winding transformer along with a three sets of tap changers which injects a voltage of variable magnitude and phase angle. The ST independently control the active and reactive power flow through the transmission line [26]. However, operation is step-wise due to use of tap changers in ST [27].…”