Hybrid inverter integrates distributed power sources – grid-independent power independence

Researchers at Oak Ridge National Laboratory have developed a smart power electronic inverter platform that can connect locally located energy resources such as solar panels, energy storage and electric vehicles together and seamlessly interact with the power grid.

Inverters convert electricity from the direct current generated by power sources into alternating current, which is used in households and in the electricity grid. Today's inverters face additional challenges: They adapt the power supply to the consumers and serve as the primary source of energy conversion between increasingly popular, but occasionally occurring power sources from renewable sources such as sun and wind as well as connection to energy storage devices, electric vehicles and intelligent devices on site. The hybrid inverter platform can do all of this while interacting with the larger power grid. For more information, see the IDTechEx report on Energy Harvesting Microwatt to Gigawatt: Opportunities 2020-2040.

ORNL researchers have embedded the computing power in the hybrid inverter platform and support real-time communication and decision-making between various control systems and the power electronics-based inverter hardware. The platform using open source software is designed to work universally with any control system – what the industry calls plug and play.

"Every company that offers solar energy, smart devices, electric vehicles, etc. usually has a different control system for their products. We want to create a way to integrate all of these systems through a common platform and function smoothly. Autonomous, distributed energy system" said Madhu Chinthavali, head of the ORNL group for electrical power systems integration. The platform encourages the installation of cleaner, more energy-efficient distributed resources while minimizing the cost of multiple devices in a home, he added.

Research enables a smart grid – a system that works autonomously with real-time monitoring and immediate power management to ensure better system stability and immunity to interference.

The platform started with the open source software VOLTTRON, which was created by the Pacific Northwest National Laboratory with funds from the Building Technologies Office (BTO) of the US Department of Energy (DOE). As a result, the ORNL scientists developed a new software agent that can communicate between various control systems, including power electronics-controlled inverter hardware.

"We've made our own component-level hardware and that's a strength we're bringing to the table," said Chinthavali. "We designed from the ground up and built our own platform from the ground up to accommodate the impact of the control panel down to the switch. This helps us design an overall more integrated system." The project is supported by the DOE's BTO and Office of Electricity programs through the Grid Modernization Laboratory Consortium (GMLC). GMLC is bringing together national laboratory resources with DOE program offices to modernize the country's power grid.

Next, the technology will scale to higher voltage systems. While households run on 120 volts, expanding the platform to 240 volts and then 480 volts allows it to be used in a commercial setting such as a factory. By further scaling the technology up to 13.8 kilovolts, the researchers can use medium-voltage applications in the larger power grid.

This scale-up work under the GMLC medium voltage hub is carried out in the ORNL Grid Research Integration and Deployment Center. The research facility GRID-C is dedicated to the development and evaluation of advanced components for a safe and resilient power grid, including the creation of scalable devices and controls for power electronics to support an autonomously functioning power grid.

"Autonomous systems for the power grid can be compared to the development of the auto industry," said Chinthavali. "The switch from manual to automatic transmission enabled a system that required less effort on the part of operators, especially in congested areas. Today, this automatic transmission system supports the transition to autonomous vehicles. The hybrid inverter platform is a similar building block for the smart, autonomous one Network of the future. "

Source and top image: DOE / Oak Ridge National Laboratory

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