Inadvertent open phase condition is a concern for distributed energy resources (DER) integration, due to the unregulated voltage on the opened phase. Although IEEE 1547–2018 standard mandates DER to detect and trip for open phase condition at its reference point of applicability (RPA), it may be challenging for DER to detect a feeder (high side of interconnection transformer) open phase condition. This paper presents an improved feeder open phase detection (OPD) method that only utilizes the solar photovoltaic (PV) or energy storage inverter's onboard resources. Controller hardware-in-the-loop (CHIL) results are shown to demonstrate the effectiveness of the proposed OPD algorithm. It is found that the OPD method can successfully detect a feeder open phase condition for $\Delta/\mathbf{Yg}$ , YgNg, and $\Delta/\Delta$ transformer, but not with $\mathbf{Yg}/\Delta$ transformer.

Grid codes around the world are requiring grid-support functions (GSFs) and standardized interoperability interfaces for distributed energy resources (DERs) to address the rapid increase of renewable energy. However, these new GSFs need to be assessed to ensure the desired power and communication capabilities exist in the field. The IEEE 1547.1 standard outlines the conformance test procedures for DER devices and is currently undergoing a major revision to align it with IEEE 1547-2018. Once it is published (anticipated in mid-2020), GSFs in commercial PV inverters in USA and Canada will be certified to the IEEE 1547.1 conformance test procedures. Several international research laboratories are collaborating to develop a versatile open-source DER testing platform that performs automated testing of DER devices. This community of laboratories is developing open-source IEEE Std. 1547.1 test scripts to lower barriers to DER vendor internal equipment evaluations, ease product compliance testing at certification laboratories, and provide research institutions a tool to study DER behaviors. In this work, test scripts were used for test verification of GSFs, including limit active power, constant reactive power, active power-reactive power (watt-var), and prioritization of GSF response for several DER devices. Sample test results for these DER GSFs and test protocol recommendations are presented in this paper.

This paper describes the application of controller hardware-in-the-loop (C-HIL) methods within an integrated design framework consisting of power electronics hardware, controller board and software, and high level management system where the grid code compliance of Smart Grid converter systems is pre-evaluated. This framework is used to evaluate a distributed energy resource (DER) converter design to grid code compliance prior to full hardware implementation. The advantage of this approach is that software errors can be identified earlier in the design process, thereby reducing the time to market.

Grid operators are increasingly turning to advanced grid-support functions in distributed energy resources (DER) to assist with distribution circuit voltage regulation, bulk system frequency control, and power system protection. The U.S. DER certification standard, Underwriters Laboratories (UL) 1741, was revised in September 2016 to add test procedures for multiple grid-support functions. Sandia National Laboratories, SunSpec Alliance, and growing community of collaborators have undertaken a multiyear effort to create an open-source system validation platform (SVP) that automates DER interconnection and interoperability test procedures by communicating with grid simulators, photovoltaic (PV) simulators, data acquisition systems, and interoperable equipment under test. However, the power hardware required for generating the test conditions may be untenable for many organizations. Herein, we discuss development of the SVP testing capabilities for UL 1741 tests utilizing a controller hardware-in-the-loop testbed that precludes the need for power hardware using a 34.5 kW Austrian Institute of Technology smart grid controller. Analysis of normal ramp rate, soft start ramp rate, specified power factor, volt-VAr, and frequency-watt advanced grid functions, and the effectiveness of the UL 1741 test protocols are included.

Several international research laboratories are collaborating under a Smart Grid International Research Facility Network (SIRFN) project to develop certification procedures for advanced distributed energy resources (DER). To effectively evaluate interoperability and grid-support functionality in DER equipment, test permutations across the full range of modes and parameters are required. It is impractical to complete these experiments manually so the project team is working to develop a software tool, associated abstraction layers, and hardware drivers to execute the experiments autonomously using the same opensource test logic. This software can then be programmed to complete interoperable DER certification experiments at DER vendor facilities, certification laboratories, or research institutions. By sharing the codebase with all institutions, barriers to adoption steadily decrease. To demonstrate the approach, Underwriters Laboratories 1741 Supplement A volt-var and specified power factor test results from multiple laboratories are presented and compared.

With increasing penetrations of inverter-based, renewable energy resources on electrical grids around the world, new distributed energy resource (DER) interconnection and interoperability requirements have been introduced to address emerging power system operator needs. The inverter-based power conversion systems are capable of communicating with grid operators, providing voltage and frequency support, and supporting the grid during faults. However, DER vendors are under pressure to quickly and reliably update the interoperability and electrical capabilities of their equipment for different jurisdictions with the rapidly changing landscape of disparate codes and standards. The necessary power hardware required for testing power systems under the wide variety of operational conditions may be untenable for many organizations. Therefore, we introduce an approach for the concurrent development of controls and application software through a controller hardware-in-the-loop (CHIL) testbed integrated with an automated testing platform that allows for the cost-effective, flexible evaluation of advanced grid support functions without the need for large and expensive power hardware. We show this CHIL capability through the demonstration and automation of interconnection tests with a 34.5 kW Austrian Institute of Technology (AIT) smart grid converter (SGC) connected to a Typhoon HIL system. We have demonstrated the CHIL system with regards to connect/disconnect, active power curtailment, fixed power factor, reactive power control, volt-var, and frequency-watt advanced grid functionality tests. For all tests, the automated CHIL testing protocols for advanced functions were sufficient to demonstrate and evaluate the grid support behavior of the equipment under test.