O&M

The future grid wavelength: Migrating SDH to Internet Protocol

The future grid wavelength: Migrating SDH to Internet Protocol

By Dominique Verhulst, Global Energy Practice Leader, Nokia

The longevity of Plesiochronous Digital Hierarchy/Synchronous Digital Hierarchy (PDH/SDH) communications networks in the utility industry is remarkable.

Used for decades to monitor and control the grid, there has been an understandable reluctance to replace them. Highly reliable and secure, they also represent a sunk cost that has repaid itself many times over.

For many  reasons, however, the time has come to retire them. Given the forces now transforming the utility industry, Internet Protocol/Multiprotocol Label Switching (IP/MPLS) is the right technology for replacing SDH/PDH. The choice of the top 20 U.S. utilities, IP/MPLS is a well-proven technology with the capabilities needed for future expansion and transformation.

The utilities industry is currently a locus point of several technology trends. The biggest influence is the shift from centralized fossil fuel-based generation to distributed and intermittent renewables. Grid management is becoming much more complex with the introduction of bi-directional energy flows that come with rooftop solar, wind farms, grid-scale battery storage and micro generation. No longer static, the grid needs communications that are more flexible and can accommodate rapid additions and changes to nodes and connections.

The digital transformation of grid management is another big trend supporting the move from PDH/SDH to IP/MPLS. Legacy serial communications were designed to support analog control systems, whereas today’s digital systems are designed to communicate using IP. There is a growing range of devices that use IP to communicate, and the communications network has to support them all. There are also more recent power utility protocols such as IEC104 and IEC61850 used in applications such as Supervisory Control and Data Acquisition (SCADA) and synchro phasers.

As new digital applications proliferate, utilities need to build on the original investment in SDH/PDH by using the installed fiber more effectively. Dense Wavelength Division Multiplexing (DWDM) systems can expand the capacity of the fiber, but IP/MPLS has the flexibility and scalability to use that capacity most efficiently. It can provide highly granular control of protection systems or synchro phasers, as well as new IP-based applications such as video and augmented reality; which are transforming everything from the training and support of linemen in the field, to drone and CCTV surveillance. Much of the Operational Technology (OT) environment is being virtualized, with virtual Intelligent Electronic Device (IED) functions, Phasor Measurement Unit (PMU) instances and protection functions.

There are certainly aspects of IP/MPLS that have to be considered carefully as you plan for their deployment. Cybersecurity is at the top of most lists. Any network or device connected to an IP-based network is exposed to cyber threats in a way that PDH/SDH synchronous networks are not. And there have already been enough cyber incidents, such as the Ukrainian attack in 2016, that this isn’t just idle speculation.

Fortunately, IP/MPLS can be secured. There are many infrastructure industries currently using IP/MPLS for mission-critical applications without security concerns. And the utility industry has developed critical infrastructure protection (CIP) standards, such as the North American Electric Reliability Corporation CIP in North America, NIS 2 and the Critical Entities Resilience (CER) directive in Europe, that establish reliability standards for grid operators, including for cybersecurity.

Teleprotection is one of the key systems for protecting the integrity of high voltage grids and is considered to be the most challenging application to migrate to packet-based networks. Early laboratory testing and validation at the University of Strathclyde in 2013 showed that IP/MPLS networks can mitigate jitter and cyber-risk, and are more than ready to support the demanding communications requirements of teleprotection systems with reliability and security. More recent testing by Siemens has confirmed this.

IP/MPLS has sophisticated techniques to ensure quality of service, scalability, availability, reliability and security. It allows transmission of various types of communication, such as serial communications, using separate virtual paths that make the network as connection-oriented, predictable and deterministic as any Time-division Multiplexing (TDM)/PDH/SDH network. There are also advanced Quality of Service (QoS) capabilities to ensure the stringent QoS required by teleprotection systems is met constantly. The best support available uses highly granular QoS traffic engineering at the ingress to the packet network as well as the egress.

The ability of IP/MPLS to overcome multiple failures in a particular network path is especially important for mission-critical networks. With IP/MPLS, it is easier to achieve network resilience by, for instance, using equal-cost multi-path (ECMP) routing. It is also completely flexible in terms of the topology of the network. It can be based on rings, star and full mesh without restrictions, allowing maximum flexibility. Because the power utility network is no longer a static environment, this ability to be able to dynamically add mode nodes, links and interconnections is becoming more important than before.

The PDH/SDH equipment is, at the same time, getting harder to service. Many of the vendors supplying this equipment have sun-setted the equipment and stopped supporting it. As the technology ages, inevitably the engineers and IT personnel who built, maintained and operated these systems will also age and retire. Arranging service contracts from third-party vendors is increasingly difficult. In a few years, these systems  – although still as dependable as ever  – may represent a serious liability for those power utilities that still have them.

Given this situation, it is important for utilities to take a proactive approach. The day is not far off when failing SDH/PDH components will simply not be obtainable. Instead of waiting for the crisis that this situation will create, utilities need to begin now to plan for the replacement of this equipment. Major outages could potentially lead to serious operational expenditure budget hits, which could rate base repair projects. As a result, it’s better to set up a capital expenditure project that is carefully planned and tested – and regulator approved.

If IP/MPLS sounds more complicated than your old PDH/SDH network, it is true that for many staff there is a learning curve. However, the technology has now been around long enough that there are many resources available to help with the transition  – which has many advantages. In exchange for some of the extra complications, for example, IP/MPLS provides a platform for a host of new devices, virtual functions and the power of cloud and edge computing to transform the intelligence, resilience and agility of the grid.

IP/MPLS is also well-established in the telecoms industry. It has been used in 4G/LTE networks for a decade and will be the key transport and routing layer for 5G and future communications technologies. It is likely to have as long a future as has been enjoyed by SDH/PDH. It is worth the investment in making the transition, because it will ensure that the next generation of engineers are trained and ready for the communications technologies of the future. Once IP/MPLS is established as the base technology for the grid, OT teams will find that there are so many new things the network can do, the sky is the limit.

About the author: Dominique Verhulst currently heads up the Global Energy Practice at Nokia. Leveraging Nokia’s full portfolio of Fixed, Mobile, IP&Optical, Applications & Analytics and professional services products including Bell-Labs consultancy, Dominique and his team provide complete end to end solutions to Utilities, Oil&Gas and Mining companies. He is the author of the “Teleprotection over Packet Networks” e-book available on the iTunes bookstore, and co-author of several publications from the University of Strathclyde.

He has over 30 years of experience in the telecommunications networking industry, holding senior sales and marketing positions at Nokia, Alcatel-Lucent, Newbridge Networks, Ungermann-Bass and Motorola.