Grid Compliance Tests

Introduction

Today’s power grid infrastructure is going through a significant revolution. No longer are traditional, large, ‘centralized’ power generators (e.g., coal-fired, hydroelectric, or nuclear power plants) able to supply the continuously increasing energy demand in the 21st century. A major contributor to this challenge is the growing trend of mass electric vehicle (EV) adoption and widespread proliferation of EV charging infrastructure. Utility companies face the coming challenge of accommodating large, unpredictable loads for EV charging. This is further complicated by the growing adoption of variable renewable energy sources like wind and solar.

Inverter-based distributed energy resources (DERs) with interoperability and grid support capabilities are key technologies not only for generating the electricity needed for mass EV adoption, but also for ensuring reliability and resiliency of power grids. With vehicle-to-grid (V2G) investments ramping, electric vehicles (EVs) are thought of as mobile power sources, allowing additional flexibility in supplying peak power to the grid. Of course, with this flexibility comes increased complexity in controlling grid’s balance of supply and demand.

Variable renewable energy (VRE) and inverter-based distributed energy resources (DERs) in the form of solar, wind, battery storage (ESS) and EV charging stations (EVSE) are key technologies/devices to supply additional, distributed power. New DER capabilities and grid support functions (e.g., Volt-VAr, High Voltage Ride Through - HVRT) will provide a more resilient grid but will also add to the complexity of grid controls needed. Standards organizations across the globe (IEEE, IEC, UL, EN, GB/T, etc.) are scrambling to keep up with the exponential growth of DERs and their rapidly changing grid support capabilities.

Grid Compliance Around the World

Grid compliance standards vary around the world from country-to-country, region-to-region and possibly even utility-to-utility. To maximize the revenue for their R&D investments, DER manufacturers will need to test to and comply with multiple standards.

North America

IEEE 1547-2003 has long served as the most widely applied standard in utility grid codes across the U.S. It was published with the intent of institutionalizing a “get out of the way” relationship between DERs and the power grid, i.e., disconnecting a DER from the power grid whenever the grid’s voltage or frequency exceeded nominal operating conditions. However, due to increasing penetration of DERs, IEEE 1547 has undergone drastic revisions in recent years to promote advanced functionalities and communications[1]based features in DERs for participating in active regulation of the power grid rather than simply disconnecting. This led to the publication of IEEE 1547-2018 (Test Procedures included in IEEE 1547.1-2020), which has evolved to become the leading standard in the U.S. for Interconnection and Interoperability of DERs with the power grid.

UL 1741 SA was created with knowledge that the massive update to IEEE 1547 was coming, but that DER technology and renewable energy penetration levels were moving too fast to wait for IEEE 1547 revisions to be published. So, UL 1741 SA was published in 2017 concurrent with an update to California’s grid code (Rule 21) to serve as a stop gap standard until IEEE 1547-2018 and IEEE 1547.1-2020 could be completed.

Subsequently, UL 1741 SB was created to provide a certification path referencing IEEE 1547-2018 and IEEE 1547.1-2020 test requirements, effectively moving most of the UL 1741 SA test standards to IEEE 1547-2018. UL continues to update UL 1741 SB to clarify requirements until the next revisions of IEEE 1547 and IEEE 1547.1 are completed (estimated for the 2025 and 2027 timeframe, respectively. DC[1]V2G is already possible today in the U.S. by following the UL 1741 SB certification path.

In addition, there is a working group developing UL 1741 SC, focused on including enabling AC-V2G in coordination with SAE J3072. SAE J3072 Interconnection Requirements for Onboard, Utility-Interactive, Inverter Systems was published in March 2021 and incorporated requirements outlined in the IEEE standards above, and IEEE 2030.5 (see below) in addition to other supporting standards.

1547.2018 is technology agnostic and thus applies to all types of DERs (e.g. Fuels Cells, Photovoltaics, Energy Storage, Dispersed Generation) and includes both Type Tests (Section 5 of IEEE 1547.1-2020) and Interoperability Tests (Section 6 of IEEE 1547.1-2020). Type Tests provide information that is used to verify if the DER’s interconnection system provides the proper physical response to deviations in voltage and/or frequency on the power grid based on requirements specified in the standard (e.g. HVRT – see Figure 3 below). The Interoperability Tests check the DER’s ability to communicate and exchange information with a “DER Managing Entity” (e.g. Nameplate information, adjustable settings, management information, etc.). The Management information section of the interoperability works together with many of the type tests, enabling control of the DER configuration options (e.g. set PF=0.9) through the communication interface. Nineteen states are inquiring or have plans for adopting IEEE 1547-2018, with enforcement dates having started at the beginning of 2023.