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Converged field area networks enhance smart grids

As electric utilities move to modernize their distribution systems, converged field area networks (FANs) are needed to deliver the full potential of distribution automation. With a converged FAN, utilities can monitor, control and automate distribution systems, enable distributed grid intelligence for faster response and higher reliability, and lay the groundwork for future Internet of Things (IoT) applications.

Moving to a converged FAN can be achieved by leveraging standards-based IP/MPLS and wireless networking technologies.

With LTE and IP/MPLS, converged FANs can deliver the necessary network services, security, quality of service (QoS), resiliency, and scalability throughout the distribution system. They serve as the foundation for the delivery of new grid applications and for the extension of service to users anywhere.

Why a converged FAN?

Two major trends have created a need for converged FANs.

As part of grid modernization efforts, many utilities have started to implement distribution automation (DA) in medium and low voltage grids. With automation, utilities hope to improve electricity reliability and quality, enhance operational efficiency, and optimize grid performance.

At the same time, the way energy is generated and consumed is changing. The rapid development of new technologies, such as distributed energy resources (DER), energy storage, microgrids, and electric vehicles create a bi-directional energy flow. This flow requires new approaches to power grid operation and management.

To address these changes, many electric utilities are enhancing their grids for more intelligent operations. They are adopting grid applications to monitor, control, and automate grid functions. These applications collect, process, and communicate power line data, such as frequency, voltage, and current levels. In some cases, they may also send command and control signals. All this communication must be supported by seamless and secure connections between intelligent electronic devices (IEDs) in the field, and information and control systems.

Many utilities have already deployed new wide area networks (WANs) based on packet technology, such as IP/MPLS, to support substation automation. But to address the new trends, some utilities have also deployed multiple FANs to support different grid applications (Figure 1).

For example, utilities may deploy one FAN for advanced metering infrastructure, another for power quality monitoring, and a third for protection. Each FAN may be based on a different networking technology and require its own specific maintenance and support.

Unfortunately, this approach cannot scale cost-effectively.

Figure 1: Multiple distribution FAN networks

 

Multiple independent FANs create inefficiencies

The current approach to FAN deployment leaves utilities with multiple discrete networks that must be managed and maintained independently. This leads to higher operational and maintenance costs. It restricts control, co-ordination, and communications between grid applications, it becomes a barrier to application integration, and it stalls future innovations.

More importantly, as applications become increasingly intelligent, the volume of grid information to be collected and processed increases significantly. This exposes the many limitations of the underlying network technologies used today, which make them unsuitable to continue providing the necessary communications, as can be seen below:

  • Some are becoming obsolete (analog phone lines, DS0 leased circuits)
  • Some are narrowband technologies with limited bandwidth (e.g., IEEE802.15.4g, satellite service), which makes them adequate for reading meter data, but not for more advanced applications, such as distribution automation
  • Some require line of sight (e.g., microwave), which requires extensive RF link design and hinders a utility’s ability to move and add new field devices
  • Some use unlicensed spectrum (e.g., IEEE802.15.4g), which is vulnerable to interference
  • Some have limited telecommunications industry acceptance (e.g., WiMAX) or are proprietary and do not provide an evolution path

Given the limitations, the current approach to FAN silos and their underlying technologies do not offer a path towards more intelligent grid operation. In fact, they may become a choke point in smart grid communication.

Converged FAN enables intelligent automation

A converged FAN architecture eliminates these challenges. It brings secure and cost-effective segregated broadband connectivity with QoS assurance and resiliency to all field devices, control systems, and application servers in substations and operation centers (Figure 2).  It also enables open but secure interconnection to other IP networks, if necessary.

Figure 2: Converged FAN architecture for segregated, secure, application-specific communications

 

To deliver this functionality, the converged FAN is built on two proven technologies:

  • The end-to-end network and services layer is created with IP/MPLS
  • The everywhere broadband connectivity is provided by LTE

Why IP/MPLS?

Many utilities worldwide have already deployed IP/MPLS to build their mission-critical WANs. The reasons and choices for selecting IP/MPLS in the WAN are similar to the new communications requirements emerging in the FAN. WAN deployments capitalize on the flexible Layer 2 and 3 virtual private network (VPN) capability of IP/MPLS, as well as its rigorous security, SONET-SDH like resiliency, and deterministic QoS to consolidate all critical grid communications. These advantages directly apply to the FAN as well. A Layer 2 multipoint VPN, also known as Virtual Private LAN Service (VPLS), could be particularly important when more grid applications adopt a distributed model and use GOOSE protocol[1]. And IP/MPLS is versatile enough to ride on top of different transport mediums, including wireless. Utilities can now bring the power of their mission-critical WAN to their mission critical FANs.

With IP/MPLS, utilities get highly scalable end-to-end managed services and reliable data transport with QoS and security. Each application is bound to a custom MPLS service that connects field devices in the FAN with servers in the operation centers, IEDs in substations and other FAN devices as required and with high flexibility. With the anticipated multitude of connected devices, a highly scalable network services platform with capabilities such as zero touch provisioning, FAN/WAN service integration and end-to-end service assurance is also crucial. 

Why LTE?

With its global deployment and wide industry acceptance, LTE provides the economies of both scale and wide ecosystems that enable cost-effective deployment and ongoing network maintenance. LTE’s flexible channel size allows it to cater to different bandwidth requirements, ranging from hundreds of megabits per second to tens of kilobits per second. And its advanced QoS capabilities, which include a dedicated bearer, enable utilities to provide specific QoS levels to different applications.

As LTE operates in licensed spectrum, it is not susceptible to interference. Also, it does not require line-of-sight paths, allowing utilities to reach everywhere economically with the necessary bandwidth and QoS for intelligent operations. Moreover, LTE is based on IP transport, so its backhaul fits seamlessly into the IP/MPLS WAN.

Converged FAN available today

AT&T and Nokia have introduced a private, converged FAN solution for US utilities. This new offering addresses the need for a next-generation FAN. It combines Nokia LTE network and IP/MPLS technology with a dedicated 2.3 GHz spectrum from AT&T[2]. This combination delivers the full broadband capacity, interference free wireless reach, end-to-end security, and IP/MPLS services continuity utilities need for today and tomorrow’s critical grid applications.

Readying for the future

A converged FAN built with LTE and IP/MPLS can be the communications foundation for utility modernization efforts. Optimized for anywhere-to-everywhere communications, it allows utilities to provide broadband data connectivity inside the FAN, between the FAN and substations, and between the FAN and an operations center. Once deployed, it can be an integral part of the future IoT framework. It can also be the platform on which distribution automation and distributed intelligence can continue to develop for many years to come.

For more information about the converged FAN, read the Nokia white paper “Rethinking the FAN for grid automation”.

 

[1] Generic Object Oriented Substation Event (GOOSE) protocol is used for utility substations communications and is defined in the IEC 61850 standard suite.