A recurring theme in this Straight Talk column has involved the amount of change and the pace of change many utilities have undergone to deal with the markets, aging assets and so forth. Over the past 35 years, we have seen the T&D network evolve. Automation of meter reading and of grid operation has led to a gradual convergence of what used to be a set of unique operational technologies and information systems. More recently, there has been growth in the installation of sensor-based systems and supporting networks, such as phasor measurement units on the transmission system and advanced metering infrastructure (AMI) on the distribution system. And even more grid-connected sensors and intelligent devices are expected to provide improved data to enhance distribution system operations. As we see the growth of these systems, we see a continued convergence of the supporting information technologies and operational technologies (IT/OT).
The converged IT/OT system seems to have tremendous potential to revolutionize power delivery and could support many new services, provided the proper regulatory environment exists to catalyze these services.
One such new service area supported by this convergence is the integration of distributed energy resources (DERs) at a scale not previously supported, including energy storage. However, empirical operating experiences and industry research have noted that traditional control techniques are challenged by high-penetration DERs, and while current centralized solutions have made progress, the very nature and architecture of energy management systems and distribution management systems (DMS)-based solutions may be limited in terms of the types of performance they can achieve as the number of points to control moves into the millions.
When microgrids or large numbers of DERs are integrated into the grid, multiple control processes are typically operating in parallel and are not always coordinated; and in these cases, a centralized control approach may not be sufficient as differing subsystems may unintentionally compete with each other.
To better understand the challenge, organizations such as the U.S. Department of Energy (DOE) have researched the level of DER penetration that would likely become an operational problem. Simultaneously, utilities such as Duke Energy, City Public Service of San Antonio, Toronto Hydro and others have looked to address the operational challenges by applying distributed intelligence at the edge of the grid to locally control certain assets in a decentralized approach. Early work has shown significant promise, and the North American Energy Standards Board and the Smart Grid Interoperability Panel are working with industry partners to bring a reference framework for applying distributed intelligence in an interoperable fashion to the industry. However, it is not yet a complete substitute for a centralized approach, and current thinking is leaning toward the deployment of a hybrid approach to better control the grid, a mix of centralized management and decentralized control functions. What remains a challenge is how to apply both approaches in a way that they cooperate to provide a consistent and coordinated control approach to the T&D system.
The Pacific Northwest National Laboratory (PNNL) has made substantial progress in determining what the next generation of control strategy should be for the T&D system. Earlier this year, PNNL published its reports on grid architecture, which were funded by the DOE’s Office of Electricity Delivery and Reliability. PNNL describes how concepts such as ultra large-scale systems, network utility maximization and layered decomposition can be mapped onto the physical grid structure and simultaneously allow for overall system control, while allowing for localized optimization, including functions such as microgrid islanding and reconnection.
Now that we have a proposed approach, how do we get to where our control strategies can keep up with the new assets and technologies being installed on the T&D system? Will our progress keep pace with the needs of the renewables mandates?
Similar to the recent progress in implementing distributed intelligence at the edge of the grid, a reference architecture or framework is also needed for the overall T&D system that addresses coordination and control. It seems feasible that this new control approach could be overlaid on the existing system, but applications need to be developed and tested. It appears to be an ideal area for federal and collaborative research and development to address. However, in contrast, several utilities have only implemented a minimal set of features of their DMS, outage management system or advanced DMS, and AMI data collected today is a fraction of what could be collected.
At a panel session at the recent CEATI conference, attendees were asked about their interest in distributed intelligence and interoperability; only approximately 30% expressed strong interest. So we could see a disconnect between emerging technologies and acceptance for some time. But in many ways, after 35 years of effort, it could be the industry transformation is just beginning.
Wade Malcolm is president of Laminar Energy Solutions, LLC, a start-up focused on bringing emerging technologies to the utilities market and related segments.