By Bradley Williams, Oracle Utilities
The electric distribution grid is changing rapidly, with a pronounced shift favoring the decentralization of electricity generation. Residential and business customers are taking advantage of decreasing technology costs and favorable government policy to adopt distributed energy resources (DER), including solar photovoltaic (rooftop solar), wind turbines, diesel generators, energy management systems, electric vehicles and energy storage. These rapidly proliferating resources have the ability to affect grid reliability and performance, pointing toward growing risk for utilities oriented only toward traditional, centralized distribution.
Risk or Opportunity?
Traditional grid systems were not built for the complex processes needed for managing energy resources at the edge of the grid. It’s not just the architecture of the distribution grid that is changing: Shifting business models and processes, adoption of new regulatory models, and rapidly evolving technology, communication and controls all anticipate a future grid that is multi-directional in scope.
Challenges lurk in all of this. The influx of distributed renewable generation, which is intermittent in nature, creates variability in energy supply. As consumers connect more and more DER into the grid, the intermittency of the DER creates real risks to reliability and grid health.
To further complicate matters, much of this new energy supply is beyond the view of traditional distribution grid operators-at the grid’s edge, at or near the end user. Traditional SCADA, used by utility grid operators to monitor the distribution grid, was built for a rigid operating environment, not for the level of data-driven processes required for modern, edge-of-grid generation and distribution. The lack of real-time visibility into these resources, combined with generation intermittency inherent in renewable resources, can jeopardize grid stability.
Nevertheless, empowered by technology innovation and supported by changing regulatory policies, consumers are choosing to adopt DER in record numbers and at a pace far faster than anticipated. These resources are pushing massive amounts of real-time data back onto the distribution grid, whether utilities are ready for it or not.
Forward-looking utilities and public utility commissions alike are exploring and integrating new approaches, new processes and new technologies, both to protect and to enhance reliability and service quality.
Breaking Down the Pieces
Modern distribution management requires a data-centric approach to monitoring, control and optimization of both traditional distribution and edge-of-grid needs. This begins with the ability to model the generation output profile of each and every distributed energy resource, accounting for location, condition of use and other attributes unique to each asset. For example, when looking at each rooftop solar resource, the ability to account for clear or cloudy skies, latitude, time of day, day of year and direction and pitch of panels are all important factors.
DER assets like rooftop solar, wind turbines, fuel and batteries are each different. So, too, are their impacts on the distribution grid. By being able to more accurately model generation output profiles and forecast where and how DER growth will impact the grid, utilities can realize a number of mission-critical benefits, including:
“- Reducing the capacity for intermittency to cause disruption and safety issues
“- Eliminating the need to bring additional, costly generation resources online
“- Minimizing customer minutes of interruption via improved generation output profiling
“- Improving resource planning to support DER growth
Reducing Intermittency Disruption and Safety Issues
The addition of large amounts of distributed generation to the traditional electric grid can threaten system balance. If distributed generation exceeds load at the substation level, it can cause unusual distribution flow patterns, or reverse flow, with power flowing from the substation into the transmission grid. This, in turn, can produce high-voltage swings, which can harm customer equipment. High levels of distributed generation also can add stress to circuit breakers, making the distribution system complicated to operate, particularly during both planned and unplanned outages, according to a Massachusetts Institute of Technology study.
Historically, supervisory control and data acquisition (SCADA) systems have been the foundational tools used to provide utility real-time operations with the ability to control the movement of energy around the generation-to-distribution grid. Typically, though, utility monitoring and control stopped at the substations or, in some cases, some of the distribution feeders just beyond the substation. So, most DER falls outside of the utility’s direct monitoring and control, leaving substations and equipment susceptible to the situations described above.
For utilities to better manage these issues, it is becoming increasingly necessary that their advanced distribution management systems or network management systems have end-to-end visibility, right down to the individual DER. Being able to monitor and model swings in distributed generation and balance that with consumption patterns will allow for more efficient control of this new network design.
Eliminating the Need for Costly New Generation Resources
One of the biggest utility benefits of DER is its potential ability to allow the utility to be more proactive in its use of energy and, at the same time, more inclusive of its customers. As the total megawatts of DER generation available at the edge of the grid increase, the revenue loss to utilities created by more consumer-generated power and the cost of more inclusive monitoring technologies can be mitigated by the decreased need for the utility to finance and build costly new central generation resources. In an era of declining utility revenues, increasing environmental regulations and consumers asserting their energy independence, this is a win-win-win for all parties.
Minimizing Customer Interruptions via Better Load Profiling
While utilities can’t control how or when consumer DER are connected, they can use their advanced distribution management system and analytics to reduce the risks DER pose through better modeling of generation output profiles.
Here is how advanced distributed grid (DG) modeling-at every transformer or LV/secondary load point, rather than at the substation or feeder level-works: A true generation output model is derived from aggregated net-metered AMI (advanced metering infrastructure) loads minus the sum of the DG generation output modeled forecast. Each type of DER has its own generation model or schedule, derived from customer DER records and specific class models. Modeling photovoltaic (PV) generation is particularly challenging, as the generation values of a PV system are dependent on many changing factors including latitude, time of day, day of the year, direction and pitch of the solar panels, and current weather conditions.
Advanced DG modeling, along with the automated business processes to keep these models current, is critical to managing the granularity of customer DER on the distribution grid. Failing to adequately manage and model this DER generation output can put an increased strain on the distribution grid-in particular, distribution protection and voltage regulation. Equally important, this type of modeling needs be scalable, enabling the utility’s critical operational systems to effectively manage its distribution system even for the worst possible weather events.
Improving Resource Planning to Support DER Growth
The ability to more accurately model generation output profiles, as previously described, combined with analytics that take into account geographic locations and a number of other demographic factors, can greatly aid a utility in proactive advanced resource planning.
By more accurately modeling generation output profiles and forecasting where and how DER growth will impact the grid, utilities will be able to improve their own long-term resource planning.
The traditional, mono-directional grid is evolving-by utility vision, customer choice and regulatory support-and the outlier growth of DER is going to continue. By applying proactive business processes and edge-of-grid technologies to the issue, utilities have the opportunity to remain engaged and relevant in the emerging 21st century grid.
Bradley Williams is vice president of industry strategy, Oracle Utilities. Williams is responsible for Oracle’s smart grid strategy as well as utility solutions for outage management, advanced distribution management, mobile workforce management, work and asset management and OT analytics. Williams has spent the last 30 years driving innovation in the utility industry in roles, including T&D power system engineering, technology development, asset management, and industry analyst.