While we are told about the need for a “smart grid,” we don’t hear as much about what’s actually being done to make it smarter. Advanced distribution management systems (ADMSs), a leading technology being explored at the local level, can help utilities better understand and control their increasingly complex grids.
Deploying an ADMS can be a very complicated process, and utilities fear the unintended consequences that could end up damaging performance instead of improving it. A facility at the National Renewable Energy Laboratory (NREL), Golden, Colo., is helping companies address these fears by providing a testing platform to emulate how distribution systems will react to an ADMS implementation before it’s put into place.
ADMSs are still very new, and the term can be defined variously, depending on who is using it. In general, these packages can incorporate all or part of what we now know as existing outage management, distribution management and supervisory control and data acquisition systems. While major players such as ABB, GE, Schneider Electric and Siemens offer comprehensive solutions that encompass all current functionalities, most current utility customers adopt a module-by-module approach. Voltage management, which enables grid operators to keep voltage levels closer to what they actually need during peak demand periods, is a popular first step.
The ADMS Testbed incorporates hardware and software to realistically represent a power distribution system for evaluating ADMS performance in real-world situations. It adds new functionality to NREL’s Energy Systems Integration Facility, opened in 2013, which incorporates a megawatt-scale electricity, heating, cooling and fueling grid to enable integrated experiments that aren’t feasible in real-world conditions.
“The ADMS Testbed represents a leap in ESIF capabilities,” said Murali Baggu, NREL’s laboratory program manager for grid integration. “We are not just evaluating a device or system, but we are evaluating a system of systems in a real-world utility environment.”
A recent evaluation for Xcel Energy helped the utility understand the level of effort required to properly integrate an ADMS-enabled voltage-control program. An ADMS uses its own virtual model of a distribution system to automate grid operations. However, that model is only as accurate as the data it receives from the utility infrastructure.
A process called “data cleansing” helps ensure accuracy by identifying incomplete or inaccurate parts of the data and then replacing, correcting or removing it, as needed. Because this is an expensive, time-consuming process, Xcel’s managers wanted to know just how much data cleansing they needed to do to ensure a successful voltage-control implementation.
The testbed was integrated with an ADMS from vendor Schneider Electric, Baggu said. Preliminary results from the simulation showed that an ADMS model fed with lower-quality data resulted in voltages higher than necessary along with multiple added utility-equipment operations. The highest quality model resulted in significant reductions on both and showed increased energy savings.
For the small Colorado utility Holy Cross Energy, the testbed was able to verify the ability of real-time optimal power flow (RTOPF) control algorithms—also developed by NREL—to regulate the distribution voltages of a range of distributed energy resources (DERs) throughout the Basalt Vista Affordable Housing Community. Homes in this small residential community are all equipped with DERs, including solar panels, storage batteries and heating systems that create their own local grid, capable of sharing electricity between neighbors.
To create this network, NREL programmed the RTOPF algorithms into controllers within the homes. Holy Cross Energy was able to successfully deploy various control techniques locally. The testbed was used to evaluate how well those local controls would interface with Holy Cross Energy’s ADMS (provided by Survalent), which also controls older equipment, including a load tap changer at the substation and line voltage regulators. The ADMS proved capable of making automatic changes to boost the contribution of DERs within the Basalt Vista grid, reducing the community’s demand on the larger system.
“We demonstrated how the DERs can be controlled at an aggregate level, enabling the ADMS to use the DER assets without having to exert direct control,” Baggu said.
With these two successful applications, and a positive partnership studying solar integration with Xcel Energy and Hawaiian Electric Industries Inc., Baggu and his team are looking to develop additional use cases for the testbed.
With the well-established testbed, Baggu said, “We can really help to de-risk the technology and understand the optimal benefits of different ADMS applications for specific utility needs.”