Nonlinear Magnetic Equivalent Circuit-Based Real-Time Sen Transformer Electromagnetic Transient Model on FPGA for HIL Emulation

Strategic power-flow control using a Sen transformer (ST) can be a robust and cost-effective solution to relieve grid congestion due to increased installation of renewables. The ST consists of a multiwinding transformer and tap changer that can regulate the power flow through a transmission line by injecting a series-connected controllable voltage. This paper develops a real-time high-fidelity magnetic equivalent circuit-based electromagnetic transient model for the ST on the field-programmable gate array (FPGA) for hardware-in-the-loop applications. This geometry-based model was developed to depict the major flux paths in the transformer core, and complex nonlinear phenomena, such as saturation, hysteresis, and eddy currents. The entire real-time ST model and other power system components are emulated by hardware description language, employing the 32-b floating point precision on the FPGA chip. A fully paralleled and pipelined hardware architecture is developed to achieve accurate real-time emulation as well as the lowest latency and smallest hardware resource consumption. The real-time results are validated against 3-D finite-element simulation using JMAG software.