NREL builds national capacity to reduce risk of major changes in grid infrastructure

NREL’s Power Electronic Grid Interface (PEGI) platform will quickly take power grid innovations from prototype to the field

As the power grid makes a historic transition to renewable and distributed energy, even its organizing principles are changing. Incoming power electronics, such as inverters that interconnect solar panels and battery systems with the grid, could drive a large-scale shift in grid technology from electromechanical to electronic, and rigid physics to programmability. This transition requires a thorough examination of how to develop, control and deploy future power electronics devices for energy systems, which is now possible with NREL’s Power Electronic Grid Interface (PEGI) platform.

PEGI is part of NREL Advanced Research Platform on Integrated Energy Systems (ARIES), the nation’s leading research site for proving advanced energy system concepts. ARIES allows research platforms to be combined for almost unlimited scope, allowing PEGI to explore the various impacts of power electronics on the network, including everything from consumer electronics like modern refrigerators and electric vehicles, to inverter-based resources like wind, solar PV, and battery systems, and the next generation of grid technologies that are revolutionizing medium and low voltage power systems.

NREL hosts 20MW of wind, solar, hydrogen, vehicle, storage and other resources, all of which exist on the PEGI research platform, and can be used to emulate a wide range of events and electrical system configurations. Photo courtesy of NREL.

“We are seeing a wave of interconnected power electronic devices at all levels of the power grid, and we have no precedent that can tell us exactly how to do this,” said Barry Mather, head of power electronics research. devices and systems integrated into the NREL. “This is a critical time for industry and network planners to understand the technologies shaping their systems and find solutions to their specific needs. PEGI is above all an asset for partners to experiment in a realistic and risk-free environment.

Megawatt Scale Plug & Play

A defining aspect of PEGI is the freedom to model megawatt-scale network scenarios. PEGI focuses specifically on grid stability issues such as control of inverters forming the grid, operating the grid with large amounts of inverter-based resources, and interconnecting wind and solar power plants.

PEGI has a dedicated power system: when electricity is hardwired into NREL campuses from the local utility, it first passes through a controllable network interface that allows researchers to customize power conditions. food. At this interface, researchers can invent network scenarios: an outage, an outage, or a 100% renewable energy system, for example. Downstream of the network interface, the PEGI equipment then evaluates the responses and controls the interactions of the power electronic devices under test.

NREL’s PEGI framework provides a customizable power grid environment, enabling megawatt-scale experiments for power electronics devices. Photos by Werner Slocum, NREL.

PEGI provides users with a power systems sandbox to read device operations for any power technology, in any scenario, or with any system design. It provides a very realistic environment to minimize the risks of future technology and its effects on network stability, interactions with other devices, and overall performance. PEGI can transport technologies into the future by bringing to life network configurations that do not yet exist in lab security.

Core PEGI assets

  • A 2 MVA PV inverter to represent inverter-based resources and quickly prototype controls
  • A dynamometer driven 2-MVA synchronous machine to represent conventional generation and operate as a synchronous condenser
  • A medium-voltage impedance network to reproduce the fast time-scale dynamics of power systems
  • Connect to real-time digital simulation capabilities for advanced hardware experiments in the power loop.
  • Connecting to megawatts of various distributed energy resources: multiple energy storage technologies, electric vehicles and chargers, electrolyzers, etc.
  • A pad dedicated to partner equipment to install and interface with the PEGI platform

In addition to walk-in technology validations, PEGI is a unique space to tackle one of the thorniest issues in renewable energy and power electronics: How to best integrate inverter-based generation for different systems? PEGI offers answers to this looming question by allowing researchers to adjust the share of traditional or renewable resources, and experience its impacts at an industry-relevant power level.

Entering an era of inverter-based resources

“If they aren’t already, many operators will soon be faced with questions about how to maintain system stability as renewable energy mandates lead to a greater share of inverter-based resources. But realistically, there is no single answer other than every system is different. The special role of PEGI is to show very precisely how a system would perform under future scenarios and future mixes of renewable and conventional resources. Mather said.

Power electronics is a type of generation fundamentally different from the old electromechanical machines. An advantage of such power electronics is that engineers can program and access a wide variety of commands, which are currently being explored for inverter-based resources in a global consortium.

the UNIFI (Universal Interoperability for Grid Forming Inverters) Consortium co-led by NREL addresses this topic by bringing together more than 40 organizations from industry, academia, utility and government to share knowledge and reduce risk at the border of network support controls. PEGI plays a leading role in this effort by enabling collaborators to quickly develop and demonstrate inverter controls in many operational environments. Among other projects, the UNIFI consortium will use PEGI to validate specifications that ensure interoperability requirements for grid-forming inverters from various manufacturers.

“There are so many types of network commands for inverters that we need to know which commands are best in which situations,” Mather explained. “With PEGI, we have a great place to assess controls, such as the next grid formation methods, as well as other resources and controls. It’s a unique environment to replicate the mess and diversity of the real network to see what actually works.

As an example of PEGI in action, NREL has pioneered and proven grid formation controls in several applications. NREL and GE used PEGI to demonstrate the first ever type 3 wind turbine grid formation operation— wind technology that can now provide fundamental stability to the power grid.

Another PEGI first app will be support the island of maui, where the instantaneous share of renewable energies tends towards 100%. NREL has created a tool, the integrated dynamic and scheduling model on several time scales (MIDAS), to help operators manage the scheduling and stability of renewable resources. After validating basic aspects of the tool, researchers will now deploy it to a system-wide scale using PEGI, with support from the DOE Solar Energy Technologies Office, as part of the SAPPHIRE project. PEGI will represent Maui’s 300 MW of renewable assets, which will soon exceed 300 MW, in combination with other generation, to show that MIDAS can inform operations when renewables represent a larger share of the generation mix.

NREL researcher Jin Tan leads the MIDAS project, which provides multi-timescale analysis of dynamics and planning for highly renewable systems. MIDAS will now use PEGI to test the software on a replica of the Maui power grid.

Research capacity for urgent action

Like the growth of distributed energy resources looks decidedly positive for the years to come, all eyes are on infrastructure and operations, and how to reliably manage so many new resources when they present such fundamental changes to the underlying network. More than ever, the power grid needs research that rapidly validates new solutions for various situations.

PEGI is an original research space with the latest power grid infrastructure and emulation capabilities, with the ability to streamline the transition to a more modern grid by subjecting new concepts and technologies to the rigors of real-world operations. For a future grid dominated by power electronics devices, PEGI is America’s most advanced platform for evaluating stable, resilient, and low-cost power grid solutions.

Partners interested in learning more about the possibilities of using PEGI can contact Barry Mather.

Learn about the research challenges that are addressed by NREL’s Power Electronics Network Interface.

Article courtesy of National Renewable Energy Laboratory



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