Smart Grid

Open Field Message Bus (OpenFMB™)

Interoperability between devices, systems and applications is important for several reasons:

• Industry-changing activities such as distributed energy resources (DER), microgrids and advanced demand response (ADR) require disparate field devices to work together remotely with little delay.
• It is key to the operation of a more efficient, cost-effective and secure grid. Successful interoperability allows utilities to leverage existing grid network infrastructure and underutilized assets.
• It reduces the effort in device configuration, management and commissioning.
• The expected and growing implementation of DER and microgrids will require distributed analytics and operations. Equipment and application interoperability will gradually reduce the hidden costs and inefficiencies with siloed, single-function solutions through the use of an OpenFMB.

What is OpenFMB?

OpenFMB is a reference architecture and framework for allowing distributed intelligent nodes to interact with each other. These nodes manage distributed resources that communicate via common semantics and federate data locally for control and reporting. The benefits of OpenFMB include:

1. Supports field-based applications that enable scalable peer-to-peer publish/subscribe architecture using distributed logic as well as centralized logic.
2. Data-centric rather than device-centric communication including support for harmonized system and device data.
3. Reduces latency and creates distributed intelligence opportunities to manage local grids in the most efficient way based on local resources and conditions.
4. Enables grid devices to speak to each other, e.g. meters, relays, inverters, cap bank controllers, etc.
5. Allows legacy equipment to be retrofitted for new capabilities, features, and extended life.
6. Facilitates data integration across previously siloed domains within the utility. Standards for OpenFMB are being developed through SGIP, and led by utilities (largest IOU, Muni and Co-op) based on their priorities and interoperability demonstration experience. It is important to the utility industry for several reasons:
   • Accuracy: Provides accurate control and alleviates intermittency of distributed energy resources
   • Scalability: Provides the ability to scale independently, as needed, without needing a system wide rollout
   • Reduced Costs: Takes cost out of the business by reducing integration time and effort
   • Security: A distributed grid is more resilient and can be made more secure

Duke Energy is proud to be an innovator and participant in SGIP with the development of OpenFMB standards. The results of these efforts are in operation at our Mount Holly facility.

Mount Holly Use Cases

The OpenFMB framework supports a variety of business cases that require a high-performing and secure field bus to interconnect field devices in peer-to-peer networks as well as existing field device to central control centers. The following are the initial use cases being tested at the Mount Holly facility: 

Microgrid Optimization Use Case

When the microgrid operation is in either grid-connected or islanded mode, optimal schedules are needed to be generated and dispatched to the active distributed energy resources and other controllable load assets. The optimization algorithms utilize inputs from weather, time-of-use rates, interchange requirements and emission targets to influence its short-term and long-term forecasts of its available resources on the microgrid. These microgrid dispatch schedules can be integrated into the back-office SCADA (supervisory control and data acquisition) systems (i.e. EMS, DMS) and administered by its utility operators. 

Unscheduled Islanding Transition Use Case 

In order to ensure a seamless transition from grid-connected to islanded mode of the microgrid when the state change is unplanned, the triggering event (i.e. grid outage, security event, grid stability issue) must be detected by intelligence at the point of coupling (PCC) to initiate the island recloser (or switch) to open and start the use case. Upon the abrupt opening of the recloser at the PCC, the battery inverter will receive the open status message and automatically switch the battery system from current source mode to voltage source mode. Additionally, the microgrid optimization application and the back-office SCADA systems will receive the PCC’s open status and battery’s voltage source mode notifications to update their models and confirm the successful unscheduled island transition operation. 

Island to Grid Connected Transition Use Case

This scenario deals with successfully resynchronizing and safely reconnecting the operating microgrid island back to the main power grid without a black start condition. Distributed intelligence within the battery energy storage system must choreograph its dispatching resources on the microgrid to balance the voltage, frequency and phase-angle performance of the main power system. Upon power being restored to the main grid and permission granted from the back-office SCADA systems and/or utility operator, the island recloser (or switch) will initiate the synch-check activity, which will only close and reconnect the PCC to the main grid when sufficient conditions are met. Following successful reconnection, the battery inverter is returned to current source mode, the back-office SCADA systems receive the status updates, and the microgrid optimization application is reinitiated with its changed state.