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Energy Systems Integration Newsletter October 2018

NREL and SDG&E Scale Up Microgrid Study, Torres Testifies on Blackstart, and NREL Launches Residential Storage Research with Arizona Utility

Solar panels in front of a mountains, clouds and a rainbow.

NREL, SDG&E Collaboration Scales Up Microgrid Study in Borrego Springs

Borrego Springs, a remote and weather-battered town northeast of San Diego, is the proving ground for next-generation microgrid control. To be sure, the proving ground actually exists on a simulated copy of the town in the Energy Systems Integration Facility’s computers and grid simulators. Here, NREL and San Diego Gas & Electric Company (SDG&E) hope to understand microgrid control and operation for the at-risk community.

NREL’s multimegawatt grid simulation capabilities can scale up the microgrid research to the size the city needs. With approximately 30 MW of rooftop solar, there are questions about microgrid control that Borrego Springs will be better able to answer in a risk-free environment.

The collaboration with SDG&E will help more than only the fire- and storm-prone California community. Technical and economic lessons learned from the research will serve utilities and microgrid developers hoping to deploy at a similar scale. The work has also helped establish standards around microgrid controller testing. Read the full story about expanding resiliency for Borrego Springs.

NREL and Arizona Utility Start Large-Scale Residential Battery Study

With home battery energy storage systems (BESS) gathering market momentum, residents and utilities worldwide are weighing the benefits of storage. To understand this emerging technology, one utility in central Arizona is collaborating with NREL to launch one of the largest BESS studies to date, with the potential to reach up to 4,500 of its customers.

Salt River Project (SRP), a major utility in one of the sunniest locations in the United States, is providing qualified customers financial incentives to purchase a residential BESS. Customers can be selected to participate in a research study that provides a large-scale analysis of the benefits and impacts of BESS technologies. NREL will assist the utility throughout the 3-year program by evaluating battery technologies and interpreting data about customer battery use.

The initial phase of the project will use research capabilities found only at NREL, including the Energy Systems Integration Facility’s high-performance computing to manage the millisecond-to-minute resolution data and advanced battery testing in the Thermal Test Facility. Subsequent phases might use data from customer battery use and BESS performance, allowing NREL researchers to develop modeling and simulation tools to assess the customer benefits and distribution network impacts of BESS.

With energy storage technologies gaining importance, this study is a landmark effort to understand the value that BESS technologies will have for both customers and utilities. The breadth and resolution of data combined with the modeling and scenario analysis performed by NREL will constitute a critical look at the foreseeable impacts of the storage industry.

Read Utility Dive’s coverage of the collaboration.

Torres Testifies on Blackstart at Senate Committee Hearing

"You don't want to imagine it, but there's probably enough movies that are out there that we don't need to imagine anymore," Sen. Lisa Murkowski began as she brought to order a hearing of the U.S. Senate Committee on Energy and Natural Resources on October 11. "A system-wide blackout is mostly the stuff of nightmares and Hollywood thrillers, but it's also a high-consequence threat that our nation must be prepared to respond to. The question we have to be able to answer is: Should all of the grid go down, how will we restart our generating stations, repower the lines, and safely deliver electricity to homes and businesses?"

NREL Associate Laboratory Director for Energy Systems Integration Juan Torres provided testimony to help answer that question.

After the Northeast Blackout of 2003, Torres oversaw researchers assigned to investigate its cause. This experience led him to recognize that “the economic and social impacts of a major system outage can be catastrophic" and to develop "a keen appreciation of the role blackstart concepts may play in the operation of a safe, reliable, and resilient electric grid."

What is a blackstart? If, for example, the United States' Eastern Interconnection—one of the largest coordinated power systems in the world—were to experience a system-wide blackout, the process that grid operators would use to return energy to the grid is, fittingly, called a "blackstart."

“The blackstart process relies on an established process for coordinating the restarting of specifically designated resources to energize the transmission system, bring on other generators, and get the entire system back up and running," Torres said.

For this to work, he explained, the right resources need to be available in the right locations on the grid—but the chances of this happening depend on the nature of the disaster. "History has shown severe weather or other events may cause the simultaneous loss of more than one major grid element, potentially complicating a blackstart restoration," Torres said.

And what about renewables? The evolution of the grid to a more dynamic system with distributed generation, variable resources, and energy storage makes the system more complex, but according to Torres, the good news is that these resources might offer new options to help restore the grid in the case of a major blackout.

"While the concept of blackstart is well established, considerable research is needed to ensure that blackstart functionality is appropriately considered as the grid architecture, technology, operations, and generation portfolio continue to evolve," he said.

Read Torres's full testimony, which also touches on grid modernization, microgrids, and cybersecurity as well as procurement and workforce issues. You can also watch the full video of the hearing on the Committee's website (Torres's testimony begins at approximately 40 minutes).

NREL Veteran Supports Air Force Resilience Efforts

Veterans Day is on the horizon, and for many years NREL has been supporting U.S. Department of Defense (DOD) energy initiatives through a large and growing body of partnership work. Resilience, in particular, has become an increasing priority for DOD, and NREL is uniquely poised to support the military’s goal of enhancing installation resilience.

One man who played a key role in this mission is Tony Jimenez, a recently retired Army Reservist of 25 years who spent nine months working as an NREL employee embedded with the U.S. Air Force Office of Energy Assurance where he conducted assessments of installation resilience projects. Read the full story of Jimenez’s contributions to U.S. Air Force resiliency.

IEEE Article Chronicles NREL and Hawaiian Electric Work on Grid-Support Functions of Advanced PV Inverters

On the most populous Hawai’ian island of O’ahu, installed photovoltaic (PV) capacity totals nearly half of the annual peak load for the entire island. Half of that PV capacity is located on private rooftops. With PV capacity continuing to grow, NREL and Hawaiian Electric teamed up to better understand how advanced PV inverters could help provide grid-support functions.

To study the ability of advanced inverters for voltage regulation, the team modeled O’ahu distribution feeders with high PV penetrations and simulated advanced inverter features. This work demonstrated that a critical mass of PV systems with inverters enabled with grid-support functions are needed to improve the overall voltage profile in distribution feeders and that activating voltage-regulation grid-support functions in new PV systems had no adverse impact on the utility’s voltage-regulation equipment.

Another team simultaneously investigated the frequency-support grid-support function through bulk system dynamic simulations, conventional hardware testing, power-hardware-in-the-loop testing, and a small field deployment. The team found that current PV inverters are able to respond quickly enough to mitigate realistic frequency events.

Both studies found that the impacts of grid-support function on energy production were negligible for the vast majority of customers, even in future cases with PV penetrations beyond the already-high present-day scenarios.

Learn more in a recent article in IEEE Power and Energy Magazine coauthored by NREL and Hawaiian Electric researchers.

Q&A with Bryan Palmintier: Pulling Together the Pieces with Systems Thinking

Principal Research Engineer Bryan Palmintier is a leader in grid science at NREL. Through his broad scientific career and life-lessons gained in the backcountry, Palmintier has applied his Swiss army skill set to many topics in ESI. Read our conversation with Palmintier to learn about the work he's leading in grid modernization.

NREL Leads $5 Million Initiative to Electrify and Boost Efficiency for Global Transportation Hub

NREL will lead a team of researchers—in partnership with Dallas Fort Worth International (DFW) Airport, one of the busiest airports in the world—to identify new transportation technologies that could dramatically improve energy use, convenience, and affordability for a difficult-to-decarbonize energy sector.

Working with DFW Airport and the surrounding region, NREL and Oak Ridge National Laboratory will identify technology approaches that maximize mobility energy productivity—or the overall quality of mobility with respect to time, cost, and energy—of passenger and freight options in this major transportation hub. Read the full story.

New Software for Forecasting, Visualizing Wind Power

Power system operators can welcome a new tool for visualizing wind power forecasts and pertinent wind power information. WindView is a visualization software for power system operators who will typically have many displays to look at, the wind power forecasting display just one of them. WindView is the first of its kind to provide a good display in this space and to get users started. WindView comes with a publicly available, 6-hour ahead, machine learning forecaster of wind power, called M3, which can provide a forecast to be displayed on top of an interactive map. Data in M3’s base model integrated in WindView is provided by NOAA, but users can upload both their own data, or their favorite forecaster, within the software. 

The beta release of WindView will be available on GitHub soon, and will be capable of displaying up to 200 wind farms, as well as comparison of recent forecasts to actual outputs. To learn more, visit NREL’s wind forecasting page.

Five New Pubs in ESI

A review of the potential impacts of climate change on bulk power system planning and operations in the United States – This Renewable and Sustainable Energy Reviews paper assesses how a changing climate will impact power system operations. Following a review of the relevant literature, the authors conclude that each component of the U.S. bulk electric power system will be impacted. The effects from increasing demand, increasing curtailments of thermal generation and transmission capacity, decreasing summertime hydropower generation in some regions, and decreasing wind and solar resources in some regions, will influence future power system planning and operations.

Hardware-in-the-Loop Test Bed and Test Methodology for Microgrid Controller Evaluation – In the nascent stage of microgrid technologies, controller evaluations are an important first step before field deployment. In this paper, researchers present a test bed and methodology for a proposed microgrid at the Buffalo Niagara Medical Campus. Within the ESIF’s microgrid testbed, the researchers used both controller-hardware-in-the-loop evaluation with the actual controller hardware, and power hardware-in-the-loop evaluation with battery inverter hardware, to study the survivability, economic operation, and environmental performance of the controller. This work proposes an approach for evaluating microgrid controller performance, with particular importance to microgrid controller standards, which are currently in draft form.

A New Approach for Short-Term Solar Radiation Forecasting Using the Estimation of Cloud Fraction and Cloud Albedo – This isn’t the first effort by ESI researchers to cut through clouds for solar radiation forecasting, but this report further advances the field by presenting a new model for short-term solar forecasting, the Physics-Based Smart Persistence Model for Intra-Hour Solar Forecasting (PSPI). PSPI builds off and exceeds previous models in accuracy of forecast and computation time, while incorporating cloud conditions. The PSPI model is designed to be part of a bigger grid integration software platform that produces fast and reliable forecasts.

An Assessment of Flexibility Reserves in Stochastic Modeling at Multiple Timescales – Power system operators have historically managed uncertainty with the use of operating reserves. However the landscape of today’s power systems introduces new uncertainties from variable generators, demand response from customers, and unpredictable demand profiles from emerging technologies. Advanced modeling in the form of stochastic optimization is an alternative to operating reserves, but can be computationally intensive. This CSEE Journal of Power and Energy Systems article proposes a hybrid, operating reserves/stochastic optimization model that builds off recent technological and algorithmic progress.

Capacity Market Model Considering Flexible Resource Requirements – Uncertainties from increased variable generation imply a need for flexible resources that can respond quickly to power system variability. Those flexible resources, however, are imperfectly compensated for their services in current market designs. The capacity market is especially important for attracting new flexible resources into the system. This paper proposes a capacity market model that includes flexible resource requirements, and evaluates the proposed method with case studies.

NREL Experts Contribute to Online Course on Energy Systems Integration

Businesses and institutions all over the world are facing critical energy challenges, especially from the rising costs of energy and threats to energy security from natural and human-caused events. With support from EIT InnoEnergy and the Energy Systems Integration Group, NREL experts are contributing to KU Leuven’s online course, “Energy Systems Integration: A Trend or a Revolution,” set to launch in late November 2018. The course is designed to help both students and professionals across the globe take a multidisciplinary approach to understanding how various energy systems interact—and how different areas of expertise can relate to the wider framework of the energy transition. Watch the trailer and learn more about course instructors, what you’ll learn, and how to enroll.