UL 1741 BULLETIN

Abstract

Scope: These requirements cover grid support utility interactive inverters and converters. This Supplement to UL 1741 is intended to validate compliance with grid interactive functions which are not yet covered in IEEE 1547-2003. These grid support functions may include but are not limited to voltage and frequency ride through and active and reactive power control. These Grid Support Functions may impact an inverter’s anti-Islanding functionality; therefore Anti-islanding testing will be conducted with these functions enabled as described in the applicable sections below. The intention of this supplement is to define the evaluation criteria for utility interactive inverters with grid support functions that are rated and specified as “Grid Support Utility Interactive Inverters”. This new nomenclature is intended to differentiate these products from “utility interactive inverters.” The test requirements and protocols within this section are written to allow for the testing of multiple operational parameter sets of limits and times in an effort to accommodate the needs of different grid interconnection requirements. These functional requirements will be defined in a source requirements document (SRD). This Supplement is intended to validate compliance of a EUT with a stated SRD(s) across the range of EUT operation. Multiple SRDs may be encompassed by the range of operation and or addition of functions. Where there are conflicting requirements between SRD(s), additional testing may be needed to evaluate the specific functional requirements of each SRD The requirements in this supplement are in addition to the other applicable requirements for utility interactive inverters and other applicable requirements within this standard. Following the procedures described herein, manufacturers may rate their units to a variety of different regulatory requirements or have adjustable ranges of operation that will address the needs of a variety of different regulatory requirements. The test procedures are not written with a specific regulatory regime in mind. These requirements and tests are intended to establish the template for the identified performance functions and allow for validation of conformance with specific specified performance parameters that can be used to demonstrate compliance with local requirements.  The manufacturer will utilize the ratings to state the settings for which the unit will be tested. Products shall be provided with ratings shown in SA16 including all of the defined parameters and settings in order to validate compliance.  This Supplement for Grid Support Utility Interactive Inverters was drafted using the “special purpose utility interactive inverter” CRD that allowed for manufacturer defined grid interconnection protection functions. While the Grid Support utility interactive inverters share some similar functionality with the previously defined special purpose utility interactive inverters that have potentially variable compliance requirements, the Grid Support Utility interactive inverters are required to and shall comply with the following defined requirements before they can be marked as a Grid Support Utility Interactive Inverters. Some of the requirements in this supplement are defined as optional, see Frequency-Watt (FW) – Optional, Section SA14, and Volt-Watt (VW) – Optional, Section SA15, and are not required to be included or complied with as part of the evaluation. Functions specified in this document as optional shall be evaluated if provided. The tests in this supplement verify the performance of a single unit when connected to an area EPS. The single unit may include multiple pieces of equipment. Any additional equipment necessary for the proper functioning of the EUT shall be included in the test. Performance of systems of multiple units is beyond the scope of this document. Within this supplement, the pass fail criteria is expressed mathematically or with defined limits and or time responses. Figures in this supplement are considered to be informative with exception of the test waveforms or if otherwise noted in the text.