Methods and Systems for Operating Superconducting Magnetic Energy Storage Devices

A method for controlling charging and discharging of a superconducting magnetic energy storage (SMES) device, comprising:

• connecting a three phase input terminal of a power conditioning system to a three phase power system, wherein the power conditioning system includes an AC/DC converter and a plurality of selectable switches;
• connecting an input terminal and an output terminal of a superconducting coil of the SMES device to the power conditioning system;
• receiving, by the SMES device, a DC current from the power conditioning system, wherein the SMES device includes a magnet surrounded by the superconducting coil, wherein the superconducting coil is configured to store the DC current in a magnetic field of the superconducting coil;
• connecting a cryogenic refrigeration system to the SMES device;
• connecting a control system to the power conditioning system, the cryogenic refrigeration system and the SMES device, wherein the control system includes a memory storing an equivalent circuit model of the SMES device and program instructions including a Perovich special trans function and Lambert's W equation, and at least one processor configured for executing the program instructions for:
• deriving, by the control system, a set of transcendental equations for a voltage across the superconducting coil and the DC current stored in the magnetic field of the superconducting coil based on the equivalent circuit model;
• and
• solving, by the at least one processor, the set of transcendental equations to predict a voltage VL across the superconducting coil and the DC current IL stored in the magnetic field of the superconducting coil using the Perovich special trans function theory and Lambert's W equation;
• actuating, by the control system, the plurality of selectable switches based on the predicted voltage and the predicted DC current to perform one of:
• charging the superconducting coil with the DC current and storing the DC current in the magnetic field of the superconducting coil;
• and
• discharging the superconducting coil to generate a discharge DC current, converting the discharge DC current to AC power in the power conditioning system, and transmitting the AC power to the three phase power system.