Design Distribution Automation Systems With a Unified Architecture to Maximize Efficiency in Utility Operations

by Lance Irwin, Schneider Electric, and Michael Dulaney, Cisco Systems

You’ve heard the hype around the end of the electric utility business model as it exists. Much like the global warming debate a few years ago, whether you believe the hype or not, your business will be affected by the changing views of your customers and regulators. The pace of change has been accelerating for utilities for several years, but the ability to match pace has been a concern for executives and shareholders. Akin to a runner’s wearing a suit of armor, utilities are clad with an existing electrical network that bounds the limits of their pace and sometimes forces the direction they can run.

Enter automation to save the day. Utilities cannot shed the iron jumpsuit to run the race faster, but they have found a new hope in an old friend. Distribution automation promises to make utilities better at keeping the lights on, more efficient in their operations, prepared to incorporate new sources of energy and more engaging to their customers. Figure 1 emphasizes some of the low-hanging fruit automation looks to pluck.

Adding automation comes with its own concerns. What is the appropriate level of automation? Is this just adding more weight or am I really going to be faster? Will this investment lock me into a particular vendor or limit my choices later? Approaching the automation question with a unified operations and information technology (IT) architecture will address these concerns.

A unified architecture is an open-standards and Internet Protocol (IP)-based architecture that provides network connectivity between field devices in the distribution grid to the control centers. The unified architecture is therefore flexible enough to adapt to the varying needs across the distribution network while robust enough to meet the stringent performance requirements of the utility industry.

Utilities maintain various distribution and control equipment in the field such as distribution switchgear, automated switches and reclosers. The unified architecture allows for a migration path from decentralized or centralized intelligence to a hybrid approach using centrally coordinated distributed intelligence nodes. Control equipment can provide intelligence capabilities to monitor grid state, identify and sense grid conditions and select optimal operations based on current grid state. This equipment can be connected to a field-area network (FAN) through integrated communication.

Utilities have deployed distribution automation applications, such as supervisory control and data acquisition (SCADA) headends, in central locations (the control center). Applications enable continuous monitoring and automatic control of distribution devices in the field. As automation increases, utilities deploy more sophisticated applications. Installing applications in a point solution manner adds to the complexity of the integration and limits the functionality of the total solution. Utilities should use software solutions that allow them to stand up new applications without having to do new integration each time. Often this platform is an advanced distribution management system that combines SCADA, outage management system (OMS) and distribution management system (DMS) applications. The unified architecture does not limit the architecture to a centralized intelligence; rather, it allows fluid migration toward a distributed intelligence approach as the system complexity grows.

Communications networks enable network connectivity between the control center applications and field devices, as well as between field devices themselves. In most cases, the communication network will be a combination of multiple technologies based on existing installed equipment and current application requirements. A well-designed communications network will ensure reliable and timely data delivery.

The key features of the unified architecture are:

Communications- and field device technology-agnostic and layered network services. The layered capabilities of IP-based architectures separate the application layer from the underlying communication. Similarly, standards-based smart controllers and devices separate the control algorithms and logic from the hardware and allow standard definitions and portability.

Standards-based integration of legacy assets. Whether the field asset uses serial or IP-based protocols, the unified architecture should consider translating or tunneling these over the network with high availability, security and quality. Likewise, most protocols that are supporting IP have been developed for IPv4. With the growth of standards-based (lEEE 802.15.4 and IEEE 1091.2) IPv6 networks, transporting IPv4 traffic over IPv6 network is required. A unified FAN architecture enables this using the Mapping of Address and Port using Translation (MAP-T) protocol, under development as part of the IETF Soft Wire working group.

Figure 2:  Unified Architecture

Network security and compliances. The smart grid is a critical infrastructure asset. Therefore, adding networking capabilities must integrate security mechanisms for access control, monitoring, threat mitigation and grid protection. The unified architecture considers standard methods such as IEC62351 to deploy communications, software and hardware security that do not limit the choice of vendor for the utility, allows for use of standard IT solutions and enables utilities to use their existing IT risk management processes.

Enabling high availability and disaster recovery architecture. Availability is critical. The level of availability depends on architecture design, products and network links. Consideration should be given to redundant control centers, chassis-level redundancy with seamless failover and backup power redundancy. Also, dual backhaul communications capability, dynamic IP routing and hardened hardware to industrial standards such as IEC61850-3/IEEE1613 should be preferred in cases where link failure is critical.

Enabling ease of use to reduce total cost of ownership. Deployment and maintenance costs are the biggest factors to consider. Consider devices and standards that allow automatic authentication based on device credentials and predefined configuration file download to eliminate field technician wait time or programming errors. Implement a network management system that allows for visualization on a geographic information system (GIS) map view and integrates with other control center applications (e.g., SCADA or ADMS) to share service-specific network data.

Scalability and interoperability between the control center to the end devices. Consider the tools used to manage and configure devices. These may be standards that are employed for security (such as IPSEC) or configuration software. These tools might be successful in a small-scale pilot, but they might not scale well. A detailed scalability design up front for all headend components and applications is required.

Distribution automation encompasses a wide range of possible applications, each with its own specific requirements. Specific distribution automation application requirements, objectives and planned implementation will determine the overall communications needs. Using the concept of a unified architecture for IT and operations technology (OT) systems provides utilities with many benefits compared with proprietary or stand-alone architectures.

Among the benefits is the ability for utilities to choose optimal technology based on specific application and deployment requirements, as well as to deploy a single converged IP-based architecture. Utilities also are provided with a graceful migration road map for grid modernization that eliminates millions of dollars of Capex spend associated with rip and replace of deployed legacy assets. Unified architectures eliminate additional cost, time and risks associated with design, deployment and operations of proprietary procedures for security, high availability, quality of service (QoS) and other functionality and new IT and security architectures and software applications.

In addition, unified architectures for IT and OT systems reduce operations and maintenance costs and streamline operations based on IT best practices and eliminate the need for proprietary architectures. It also enables quick and cost-effective turn up of future applications. Multiservice capabilities such as QoS and network segmentation are core to the unified FAN architecture and enable utilities to extend other applications on the same communication architecture. This reduces the costs, time and risks associated with deploying new applications.

Utilities should consider the benefits of distribution automation to ensure efficient operations. A unified approach to operations and IT architecture brings additional benefits that allow utilities to match the pace of change in the industry and incorporate new sources of energy.

Authors

Lance Irwin leads Schneider Electric’s feeder automation practice focused on delivering solutions to utility automation challenges. He previously worked for an electric utility in roles ranging from transmission and distribution line design to managing the utility’s meter engineering and operations groups.

Michael Dulaney is the utilities vertical solutions lead for Cisco’s Internet of Things business unit. Prior to Cisco, he was a senior vice president at Duke Energy International, holding executive responsibilities for the company’s operations in Latin America.

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