Overcoming IIoT, Edge Networking Challenges

As power plants and substations become more connected, the need for rugged networking equipment built to withstand tough conditions is amplified. The military has already gone through the growing pains, so utilizing technology designed to survive on the battlefield is a great option for power generators. Machined parts and stress-tested modules offer assurance that networks will be safe, secure, and reliable when deployed.

The unprecedented convergence of forces reshaping the electric power industry-from moderating demand and aging infrastructure to environmental mandates and the expansion of distributed energy resources-depends on flexible and robust grid and powerful internet protocol (IP)-based communication networks. The industry is evolving from a one-way system, where power flows from centralized generation stations to consumers, to a platform that can detect, accept, and control decentralized consumption and production assets so that power and information can flow as needed in multiple directions.

A big component of this digital transformation is the rapidly advancing Industrial Internet of Things (IIoT) and the development of sophisticated software that can take full advantage of massive volumes of data to make the grid smarter, greener, and more secure and reliable than ever. But as the number of intelligent devices that rely on the IP protocol for communications steadily increases, so too does the need for highly reliable and rugged networking devices that can withstand the tough environmental conditions found in substations and power plants.

To move forward, energy providers are actively mapping out initiatives to upgrade their equipment and integrate remote networking capabilities into headquarters-based networks. The ultimate goal is to create an automated smart grid built on intelligent electronic devices, protection relays, and IP-based networking. For these applications, the IP-based network requires far more than centralized servers and routers sitting in a secure, air-conditioned office-high-performance networking equipment such as GigE capable routers, servers, and other gear must be directly situated in the substation and power plant environment.

Plants and substations often represent a worst-case scenario for networking equipment. Environmental challenges are a major factor, because the pristine, temperature-controlled conditions generally required for sensitive, high-performance networking components are often not available. Enterprise devices are also not designed to meet highly space-constrained installation locations. Often, industrial installations of network equipment in the power industry, such as in a wind turbine, have little available room for additional equipment.

Military Grade

To solve these issues and enable deployment of enterprise information technology communications equipment where it's needed, electric utilities are starting to adapt military-grade equipment to meet specific industry needs. For the past 15 to 20 years, the U.S. Department of Defense (DoD) has been procuring rugged, compact and easily transportable IP-network technology for use by warfighters in the field and in vehicles.

For these applications, the DoD requires the best available size, weight, and power, as well as security and ruggedness-making these systems also well-suited for energy industry applications. As shown in Figure 1, these small servers and routers are designed with a modular enclosure architecture, so that the modules can be easily transported and then operated right out of their chassis, together with full power conditioning and uninterruptible power supply backup. These systems are significantly smaller than typical network servers intended for rack-mounted deployments.

1. Modular architecture. The PacStar 300 series is an example of a compact, rugged, enterprise-class router module based on Cisco technology. Courtesy: PacStar

There are several approaches to ruggedizing technology that the industry has adopted, some involving the use of proprietary network technologies. For most energy applications, the preferred approach is systems that incorporate commercial off-the-shelf (COTS) technology from vendors such as Cisco, Aruba, Haivision, Riverbed, Brocade, and so on-the top makers of secure, interoperable, enterprise-class technology.

The advantage of using enterprise COTS technologies is that energy companies have already standardized and deployed these technologies into their corporate environments. This means they don't have to change their existing environment and can take advantage of the wealth of trained experts that they already have in-house. Hardware reliability means fewer repairs and less maintenance, but perhaps more importantly, it gives power companies the confidence that their modern IP networks will be safely, securely, and reliably deployed.

Solid Chassis

The heart of any rugged module is its chassis. Because rugged equipment must be able to withstand dust, cooling fans are not an option, even though heat is the mortal enemy of electronics. In a fanless environment, efficient heat transfer is vital to ensuring durability. In the best modules-those that have been proven in military operations-the chassis is actually computer numerical control (CNC) machined from a solid piece of aluminum, and the components are solidly screwed into it. In less expensive alternatives, the chassis is made from cast material, which is weaker and more porous. Consequently, a cast chassis does not transfer heat as effectively and is not as durable as a CNC chassis. In addition, a CNC-machined chassis does a better job of absorbing vibration.

Given the central role rugged network components play in monitoring and automating power distribution, modules should not just be designed and specified to handle temperature extremes-each unit should undergo testing. An example of an environmental stress screening (ESS) chamber is shown in Figure 2. In this chamber, the modules are set up and subjected to a heavy operating load, like what they would see during a period of peak activity. They then must operate in this manner in the chamber at elevated temperatures for three days.

2. Stress test. An environmental stress chamber is used to screen out modules that can't handle environmental extremes and heavy loads. Courtesy: PacStar

As could be expected, not all units survive ESS testing. The infant mortality rate, which can vary depending on product and configuration, tends to be about 5%. The ESS step in the manufacturing process is critical, because without it, a large number of units would end up in service and fail once extreme conditions, like those simulated in the ESS, were reached.

One fundamental question is whether the manufacturer or the plant should bear the cost of stress testing. To cut costs, many vendors skimp on stress testing, passing risk on to their customers, with predictable results.

A rugged module by itself is not of much use without cables to move bits in and out. Cabling is another area that is often overlooked. Top manufacturers subject cables used inside components as well as cables supplied to customers to rigorous testing to ensure integrity and performance. Rugged systems also benefit from precise assembly, which ideally should be performed by senior assemblers. Lower cost modules typically involve outsourced assembly and looser oversight. This can result in assembly errors that can go unnoticed-right up until the unit fails in the field.

Shaking and Cooking

To avoid leaving anything to chance, it's advisable to work with suppliers whose product designs have been tested by independent labs for "shaking and cooking," and have results that have been published and are available upon request. To reduce expenses, some vendors perform their own testing in-house, and often they do not complete the full range of tests. For ultimate confidence, independent testing is an expensive, but necessary step.

Beyond the physical design, rugged modules can vary significantly in the way they condition power for their internal components. The product design must be able to deal with poor power quality and deliver a dependable flow of information even if the external power is inconsistent.

As utilities seek to improve service and take advantage of IIoT technologies, a reliable communication network infrastructure opens the door to a flexible, more modern and robust grid. Therefore, it's critical for power generators to evaluate rugged equipment-and its manufacturers-closely to ensure networks on the edge of the grid will be able handle the often-challenging conditions they regularly face. a-

-Steve Bowenis senior commercial business development manager at PacStar (www.pacstar.com).

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