Super Conducting Magnetic Energy Storage DVR based on Diode Clamped Modular Multilevel Converters

Abstract The superconducting magnetic energy storage system (SMES) has been emulated by a high-current inductor to investigate a system employing both SMES and battery energy storage system (BESS). A series-connected three phase voltage source inverter used to regulate ac voltage, and two bidirectional dc/dc converters used to control energy storage system charge and discharge. “DC bus level signaling” and “voltage droop control” have been used to automatically control power from the magnetic energy storage system during short-duration, high-power voltage sags, while the battery is used to provide power during longer term, low-power under voltages. The SMES-BESS hybrid dynamic voltage restorer (DVR) can support both short-term high-power voltage sags and long- term under voltages with significantly reduced superconducting material cost compared with an SMES based system. The DVR is a fast and efficient solution to voltage sag problems. Here we use a new configuration of DVR which is based on the parallel diode- clamped modular multilevel converter (DCM2C). Where the capacitor voltages distributed in the sub-modules can be balanced automatically without any balancing control algorithms. Keywords— Super Conducting Magnetic Energy Storage, Dynamic voltage restorer, voltage sag, modular multilevel converter.