The Phase 1 workshop report identified a wide variety of benefits that a smart inverter is capable of providing to the grid including voltage ride-through, islanding, and providing reliability or resilience services when needed by the distribution grid operator. However, these active services were specifically prohibited by the existing standards, because the distribution grid operator wanted to ensure that when a line went down, no electricity was flowing over it. In other words, during any system emergency or event, the standard (and interconnection rule) required that the distributed generation be shut-down.
UL 1741 is the standard that ensures the safe operation and installation of the inverter and smart inverter in conjunction with IEEE 1547. Working together, these standards strived to limit the potential negative impacts of distributed resources, such as rooftop solar; in the same vein, these standards are being updated to allow for these new active services to work with the distribution grid in a way that optimizes the abilities of the smart inverter while also keeping the distribution grid operating safely. A key component of that is recognition of the benefits of a smart inverter in meeting local and grid reliability needs and services. Both standards developed interim solutions to meet the requests of California. Furthermore, the standards development organizations are working to update the whole package of standards to support more widespread use and adoption of smart inverters.
Additionally, the SIWG identified that communications between and with the smart inverter are vital to the smart inverter responding to grid conditions, messages, and signals from the distribution grid operator. As part of that effort, IEC 61850 joins the discussion as the common language for this interaction. IEC 61850 is a key standard supporting the development of the smart grid generally; a part of that standard is a communication standard for devices utilizing 61850 . Recognizing the importance of a common language, that language in 61850 is a vitally important part of any communications between a grid operator and the technology.
When these standards are fully updated and complete, the engineering and physical support for smart inverters beyond California will be ready. Existing interconnection standards across the country will need to be updated to reflect these new functionalities, and new benefits and services can be realized simply through the availability of these standards. Smart inverters, and the work to update the standards, show how important standards are to integrating new distributed resources in a way that doesn’t disrupt or harm the distribution grid, but also doesn’t disrupt the on-going development of rooftop solar, or other distributed energy resources that seek to interconnect with the distribution grid. By allowing for the use of smart inverters to provide these active services, the distribution grid operator has greater certainty that the input of poor quality electricity will be minimized at the source, which relieves the pressure on the transformer, thus, it wrings more efficiency out of the grid and extends the life of the transformer.
On the customer side, the smart inverter reduces utility uncertainty about the customer’s equipment interconnecting with the grid, ensures that total costs will be lower, and has the potential to provide additional services to the distribution grid operator, such as voltage support, helping the distribution company come back up from and outage, and other reliability services. This has the ability to be a true win-win-win for all involved- all enabled by the standards.
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