Simplify the exchange of DER settings using a standard file format
By AHM Jakaria, engineer/scientist III, Electrical Energy Research Institute (EPRI)
Distributed energy sources (DER), including solar photovoltaics (PV), battery energy storage (BES) and electric vehicles (EV), are playing an increasing role in decarbonising the electric sector. In recent years, DERs have expanded their capabilities, including grid-supported smart inverter functions. However, greater DER capability means greater complexity.
In 2018, the Institute of Electrical and Electronics Engineers (IEEE) released a standard that is central to solar and battery storage systems. The standard, IEEE 1547-2018, applies to all types of DER and defines grid support functions and standard communication capabilities that aim to increase deployment without causing voltage, thermal or other violations to the power grid. As interconnection codes are updated, states and utilities typically require these new capabilities.
The functionalities defined in IEEE 1547-2018 include a large number of settings – the parameter values that are programmed into an installation or device to set them. An example is a feature called Volt-Var Control. As illustrated in Figure 1, this function defines how the reactive power of the installation (Vars) should automatically adapt as the local voltage varies. The settings for this function include a set
While grid support offers many benefits, it also poses the challenge of increased complexity and the additional steps required to (a) receive settings from the local utility, (b) program devices, and (c) provide proof that the process has been completed correctly .
Depending on the situation in a particular region, the required settings for all DERs may be the same or may differ depending on the DER size, type or the feeder to which they are connected. In some cases, unique settings can even be determined for each DER during the interconnection request process.
As the amounts of DER increase, it is critical that the settings are correct. However, with manual processes and high complexity, many errors occur. Detecting and correcting these errors can be expensive and cause delays in commission testing. Doing them incorrectly could result in damage to consumer equipment or the grid itself.
The diversity of institutions is exacerbated by the variety of ways in which they are exchanged between parties. There are thousands of utilities in the US and until recently, each had to come up with its own format when sharing required settings, such as an Excel spreadsheet or PDF document. Not only are the file types different, but the way the information is organized in the file, the names used to identify each setting, and the format of numbers can vary from company to company. This makes it challenging to interpret the specified settings and configure a DER site correctly.
It’s not just a one-way problem. When developers return evidence of configured settings to tools, how should they report it? Some use a series of photos taken from inverter displays. Others use specific files from the drive supplier that contain hundreds of parameters with unrecognized labels so that utilities can determine which are the required items. These verification processes are time-consuming and error-prone, resulting in additional costs and delays for all parties.
Two years ago, EPRI and industry stakeholders wanted to solve this problem. An open working group was formed with experts from academia, consultancies, utilities, DER manufacturers and national labs. The group met weekly, discussed options and found consensus on how to tackle the problem.
The solution was to define a common file format for exchanging and storing configuration settings for DER. The chosen format is human readable for inspection without special tools, but can also be used electronically by software systems that automatically generate, exchange and apply settings without human intervention. The file format is designed to serve three main uses:
- Utilities that pass the required DER settings to developers
- DER developers provide proof of as-programmed settings to utilities
- Store and track DER settings in software systems
The new file format is designed to be consistent, as far as possible, with the certification results reporting format identified in IEEE 1547.1-2020, which defines a test procedure for DER based on the IEEE 1547-2018 standard. Two aspects were kept consistent:
- A comma separated values (CSV) file format was used. A CSV file is lightweight in terms of size and the processing required to parse it. CSV can be opened or created by almost any text editor or Excel.
- Parameter labels, data types, units and possible value options in the new settings file format were kept as consistent as possible with the performance indicators identified in IEEE 1547.1.
The specification for the standard file format is free to download here. The document explains the criteria needed to create a DER settings file in the standard format. Developers, installers, and utilities are encouraged to use this specification to create DER settings files for sharing with other parties.
How can companies benefit from this development? Let’s look at some application examples:
Application example 1: Settings specified by the utility
A new solar or storage device is connected and the local utility company must advise the developer what settings are required. Whether these settings are system-wide or site-specific, the need is the same. The utility provides the developer with a CSV file via download, for example from an online application management system.
The utility created the file in the standard format. This eliminates ambiguity regarding the contents of the file, the labels for each parameter, the units for each value, etc.
When the developer receives the file, they understand the content because they are familiar with it. It is the same format used by utilities everywhere. Because the format is widely used, the developer’s software systems and site programming tools load, parse, and apply it to DER. Employees can view the file, but the programming of settings in the DER is done electronically and automatically.
Application example 2: Settings applied by the developer
During commissioning testing, or at any time afterward, a developer will want to read out the configuration of a solar or storage DER so that it can supply it to the utility. The developer connects his field tool to the communication interface of the DER and reads the settings. The tools save or export these settings in the standard CSV file format that is later uploaded to the tool’s online application management system.
When the utility receives the file, its contents are understood because they are familiar with it. It is the same format used by developers everywhere. The utility’s software systems can electronically handle the file and immediately compare the applied settings with what is specified, to make sure everything is correct. Ideally, the entire process of DER configuration, readout, and verification by the utility could take place in seconds.
Although the main purpose of the standard file format is the error-free exchange of settings, it can also be used as the native save format in systems-of-record for utilities or developers. For example, a developer may maintain a database of all DERs they have deployed, including the settings they have applied to each DER. If there is a need to revise this information in the future, it can be opened in CSV format and shared directly with others.
AHM Jakaria works as an engineer/scientist III at the EPRI in the Distributed Energy Resources (DER) group. Smart DER configuration settings and DER management systems (DERMS) are some of his areas of research and can be reached at email@example.com. The outcome of this work will contribute to future developments of the IEEE 1547 standards.