In this paper, design of a compact high frequency four-port transformer for a Solid-State Transformer (SST) arrangement is presented. Unlike other SSTs, the four-port system integrates three active sources and a load port with galvanic isolation via a single transformer core. In addition to this feature, one of the three source ports is designed to operate at Medium Voltage (MV) 7.2kV for direct connection to 4.16kV AC grid, while other ports nominal voltages are rated at 400V. The transformer is designed to operate at 50kHz and to supply 25kW/port. Thus, the proposed system connects the MV grid, Energy Storage System (ESS), PV, and DC load to each other on a single common transformer core. Based on the system power demand and availability of renewable energy resources, utility and energy storage ports can either supply or draw power, while PV port can only supply power, maintaining the required demand for the load. This work focuses mainly on the High Frequency Transformer (HFT) design. An extensive study is carried out to obtain the optimal, compact, cost effective, and high efficiency model. Modeling, mathematical, and simulation results are derived and presented to demonstrate the viability of this design.
Design of Nanocrystalline Medium-Voltage Medium-Frequency Three-Phase Transformers for Grid-Connected Applications
This paper presents the design of a three-phase three-limb high-efficiency medium-voltage medium-frequency transformer with an integrated leakage layer using ribbon-based nanocrystalline cores for three-phase grid-connected applications. The design methodology is based on a custom-core approach developed by a series of design equations that allow the user to select a design that best fits the transformer specifications. A 150kVA 10-kHz 5-kV-to-400-V three-phase three-limb transformer is designed to validate the proposed design method. In addition, a series of experimental characterisation tests are conducted to measure the performance of the design according do the theoretical performance.
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- IEEE Energy Conversion Congress and Exposition (ECCE)
- Sponsoring Org:
- National Science Foundation
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