Managing the Operational Challenges of the Distribution Grid

The proliferation of Distributed Energy Resources (DER), including renewable sources of energy such as wind and solar, and the growing capabilities of consumers to control and manage their own demand, is having a profound impact on the electric power industry. As these two elements increase, distribution infrastructure is being exercised in ways that it was not designed for.

Two-way flows of energy, voltage surges, and circuit phase imbalances are three examples of the challenges that the distribution system operator has to deal with. As more of these resources are added, the inherent mass and inertia in the system is diminished, resulting in larger frequency deviations and instability in the system.

Dealing with the increase in operational challenges will require the distribution system operator to have more visibility to these resources and the ability to control them in real-time to support grid operations. Furthermore, the operator will need the ability to analyze the impacts of these resources on the distribution grid and to schedule their operation, while taking into consideration the capabilities and limitations imposed by the grid.

Conventional Distribution Management Systems (DMS) provide visibility and control down to distribution substations, feeders, and some primary circuits. They utilize traditional, mathematical, model-driven methods, such as state estimation and power flow calculation, to analyze the grid and determine operational strategies and schedules to ensure the reliable operation of the system. The problem with these methods is that the mathematical circuit model data (such as line impedances) for the last miles of the grid—as well as the secondary and tertiary circuits (where most DERs and Demand Response (DR) capabilities are located)—are not readily available. As such, the reach of most DMS installation is limited to substations and primary circuits, for which model data is available.

A modern Distributed Energy Resource Management System (DERMS) overcomes this problem by utilizing data-driven grid analysis tools, where there is abundance of field data, as collected by Advanced Metering Infrastructures (AMI), smart devices, and  conventional Supervisory Control and Data Acquisition (SCADA) systems. These tools utilize field data along with basic topological connectivity information, as obtained from Geographic Information Systems (GIS), to calculate and analyze grid conditions. The DERMS augments the DMS by extending its reach to the customer-side of the meter and to customer owned load, generation, and storage assets.

Other basic functional capabilities of a DERMS include:

• Collecting real-time data from field assets
• Analyzing the current state of the distribution grid and identifying bottlenecks and operational issues
• Calculating the current and forecasting future capabilities of DER and DR assets
• Calculating the optimal operating schedules while addressing distribution grid limitations
• Dispatching and controlling field assets in real-time
• Performing what-if analysis and studies
• Monitoring performance of field assets
• Ensuring cyber security down to customer-side of the meter
• Calculating incentives and billing determinants and settling with customers

As the use of renewable resources continues to rise, the Distributed Energy Resource Management System will provide the various communications, control, and analytical capabilities to enable the distribution grid operator to address operational challenges. With proper visibility and situational awareness to all distributed generation and load assets, along with the capability to analyze the distribution grid circuits and conditions, the grid operator will be able to address operational issues using the vast capabilities provided by DERs, DR, and smart field devices to accommodate the increased levels of these resources in the system.

About the author:
Dr. Farrokh Albuyeh has more than 30 years of experience in the electric power industry, developing and implementing power system applications and systems, as well as managing and delivering projects. In his role as Senior Vice President Smart Grid Projects at OATI, he is involved in the development and delivery of solutions and services for wholesale energy markets, applications for scheduling and managing DR and DER, as well as the development and delivery of solutions to support distribution grid renovation. Dr. Albuyeh has specific experience with technical analytical studies, application software development, providing consulting services, managing, and delivering large-scale projects.