Growing penetrations of highly variable renewable energy sources, most notably distributed solar photovoltaics (PV) are leading to concerns about grid voltage and frequency deviations. Inverters and power conditioning systems (i.e., batteries) have the ability to help stabilize the grid, and functional definitions were standardized in the International Electrotechnical Commission (IEC) Technical Report 61850-90-7. A growing number of jurisdictions are mandating their use, but certification laboratories, utilities and other stakeholders need a test procedure to ensure inverters and other connected devices perform appropriately.
To serve a basis for international certification standards for several of the functions defined in IEC 61850-90-7, Sandia National Laboratories (U.S.) created “Test Protocols for Advanced Inverter Interoperability Functions”. Several SIRFN participants across the U.S., Europe and Asia have since exercised and evaluated the protocols to compare results across different grid environments. The protocol assessment has been shared with key stakeholders, such as California’s Smart Inverter Working Group, and presented in papers and conferences. This work will not only improve the test protocols for adoption by code-making bodies, but also identify opportunities to improve the design and operation of smart grid test beds. SIRFN is now expanding the work to test protocols for energy storage.
Driven by new requirements in Europe and the United States, PV inverters, power conditioning systems (PCSs), and other distributed energy resources (DERs) will provide a wide range of advanced functions to support the electric grid voltage and frequency. It is the goal of this project to compare, improve, and harmonize national and international certification procedures by developing DER testing protocols for advanced interoperability functions. To begin the process, SIRFN is working with the standardized set of functions defined in the International Electrotechnical Commission (IEC) Technical Report 61850-90-7. In November 2013, Sandia published a set of draft test protocols for the IEC TR 61850-90-7 functions to validate interoperability and functionality; these protocols have acted as the starting place for the SIRFN testing. Ultimately, the project is designed to improve the test procedures and incorporate them in national and international standards by:
- Building test-beds for advanced interoperability DER testing in SIRFN laboratories
- Coordinating the experimental testing of DER devices in the U.S., Europe, and Asia to ensure the protocols are robust to a range of electric grids and test equipment
- Comparing results from advanced DER function experiments
- Revising the test protocols to prepare it for adoption by code-making bodies
The test labs are exchanging technical information on the design and operation of the advanced DER test beds and software for executing interoperability testing, providing refinements to the test procedures and test parameters, and comparing results for different DER sizes and designs on grids with different frequencies and voltages. SIRFN laboratories including Sandia, AIT and TECNALIA have performed round robin tests using the Sandia Test Protocols on residential inverters. Through this process, the test protocols were refined and are now acting as the basis for American certification procedures in Underwriters Laboratories (UL) 1741.
As part of this effort, Sandia National Laboratories has been working with the SunSpec Alliance to create a versatile hardware/software test harness called the System Validation Platform (SVP)Nationally Recognized Testing Laboratories (NRTLs). More information on this software will be provided when it is released in April 2015.
The next phase of the project is to expand the certification protocols to energy storage system (ESS) capabilities. Currently SIRFN labs from the US, Japan, Austria, and Italy are working on this project and building certification tests for ESS grid code requirements.