Grid

SixPoint Materials and Texas Tech University will develop a photoconductive semiconductor switch (PCSS) that will enable low-cost, fast-acting, high-efficiency, high-voltage HVDC circuit breakers. SixPoint will develop the key material, bulk crystals of semi-insulating gallium nitride (GaN), and Texas Tech will design the device structure and fabricate a 100 kV PCSS. Combining the GaN PCSS with a conventional mechanical switch will create a hybrid HVDC circuit breaker suitable for a multi-terminal HVDC grid.

Virginia Polytechnic Institute & State University (Virginia Tech) will demonstrate a new concept to enable a compact, flexible, scalable, and adaptable medium-voltage (MV) distribution network for growing and changing electricity sources, demands, and usage patterns. The team will combine power electronics and MV cable benefits to create a cohesive structure that can replace bulky substation components while enhancing functionality.

GE Grid Solutions plans to develop a SF6-free high-voltage AC outdoor dead-tank power circuit breaker. The circuit breaker will be rated at 245 kV and will also provide the basis for a two-break 550 kV rated design. It will use g3 TM gas mixture for current breaking and dielectric withstand. This project is a critical step in launching a range of products that meet U.S. energy industry requirements without using SF6 technology. These products are essential to reduce the bulk electric system’s carbon footprint and greenhouse gas emissions.

The University of Connecticut proposes to develop a life-cycle management framework to accelerate and safeguard the transition of the U.S. power grid toward a sulfur hexafluoride (SF6)-free green power network. Although SF6 has several positive properties, it also has a global warming potential (GWP) 25,200 times that of CO2. Studies suggest the alternative environmentally friendly gas mixture g3TM as a promising potential replacement for SF6.

Advanced Conductor Technologies will develop two-pole, high-temperature, superconducting DC power cables and connectors with a power rating of up to 50 MW to enable twin-aisle aircraft with distributed electric propulsion to reduce carbon emissions. The cables and connectors will contain insulation independent of the cryogenic medium used as coolant and allow an operating voltage of 10 kV. Because they have intrinsic fault current limiting capabilities, the cables can protect the power distribution network from over-currents.

The average age of large power transformers (LPTs) currently operating in the U.S is 40 years, with 70% older than 25 years. Insulation failure contributes to more than 60% of LPT failures, costing the U.S. over $18 billion annually. To improve transformer life, GE Research will develop a long-term stable nanofluid dielectric to double the service life of current LPTs to at least 80 years. GE’s TiO2-based nanofluid will replace the conventional transformer insulating fluid and is expected to improve thermal conductivity by >25% and enhance dielectric strength by at least 50%.

To make the power density of electric aircraft closer to conventional aircraft, an electric power system (EPS) with high power delivery and low system mass is necessary. As an essential component of aircraft EPS, cables are necessary to transmit power from one node to another. Virginia Tech will develop a high-power density, cost-effective ±5 kV cable for twin-aisle all-electric aircraft.

Fault protection must be provided for future turboelectric aircraft’s medium-voltage direct current power systems, but not necessarily from conventional circuit breakers. Illinois Institute of Technology will develop a 10 kV/150A superconducting momentary circuit interrupter (SMCI) to provide fault protection with ultralow power loss (<1 W), ultrafast response (<10 μs or ten millionth of a second), and high-power density. The architecture comprises an SMCI with a fast mechanical disconnect switch.

GE Research will develop a safe, lightweight, and altitude-capable megawatt power cable system with electromagnetic interference shielding capability for large aircraft. The proposed 10 MW cable system is expected to achieve ten times greater power density than conventional technology without degradation by partial discharge and is fire safe and oil resistant.

There are two key engineering challenges in the development of 10 kV, 10 MW electric power distribution cables for double-aisle passenger aircraft. One is providing sufficient electrical insulation at high voltages and the second is transferring heat away from the conductors.