By Miguel Bengla, Advanced Control Systems
|Leagacy substation remote terminal unit (RTU) installation.|
When you, the substation expert at your utility, enter an aging installation and see a 40-year old transformer, 30-year old circuit breaker or the 50-year old fence that is falling apart, the old remote terminal unit (RTU) sitting in a corner might not be your first concern.
Some of the thoughts that run through your head might be: “I know the original vendor is no longer in business, so there is no one to call for support”; “There is no way I can get parts for it”; “I can’t do any IED integration or open communication protocols”; or, “But it still works and I certainly don’t have the time, budget or people to replace that old thing.”
This is not an isolated engineer in an isolated substation at an isolated utility. As Figures 1 and 2 (provided from 2014 Newton-Evans Research©) illustrate, the number of transmission and distribution substations in operation with little or no automation in the U.S. is by far larger than the number of fully automated substations. With all the available technology, one might ask how can it be that we still have non-automated substations? Isn’t this supposed to be the smart grid era?
To answer this question, technology leaders must realize that if it was simple to do, it would already be done. In addition, they must understand that while there might be hundreds of items to consider when contemplating substation control center modernization, that list of items can usually be reduced to just three: cost, people and time.
Is it possible to address these three items and optimize a substation? A state-of-the-art substation controller can be installed in an old substation at a reasonable cost, while reducing the number of people involved in the change. In addition, open TCP/IP communications, IED integration, real automation and NERC CIP compliance can be integrated into the old substation in just one day.
Legacy RTU Replacement Might not be the Answer
Most people who work in the substation automation industry know what it takes to replace an old RTU. It is much more than budgeting for a new substation controller. Most time is spent on field installation and rewiring (with all the associated testing), substation wiring diagram revisions and, in some cases, making changes to the existing SCADA master databases and displays. This often makes it prohibitive for a utility to upgrade to existing modern technology and all the possibilities it unleashes, or simply prevent the utility from losing a substation and living through all the consequences that loss brings to it, as well as the community it serves.
Industry leaders, therefore, must explore different solutions for these problems. If the solutions being offered don’t address utilities’ needs, a new solution other than replacing the legacy RTU must be found.
The Power of Upgrading
Upgrading is a solution. An upgrade delivers superior modern technology by replacing only the legacy RTU logic, control cards and processor, along with the old power supply. Existing control relays and wiring, digital and analog input termination modules, field wiring, and SCADA master database and displays, if working properly, all can be retained and left untouched. This solution results in real and significant time and cost savings and brings smart grid to the substation. It is an opportunity for today’s technology to work in last century’s installations.
This upgrade solution exists today and many utilities have already implemented it and seen proven results.
Cleco Corp. is one of those utilities. It is a public utility holding company based in Pineville, Louisiana, that has been in business since 1935. It employs approximately 1,200 people, serves approximately 286,000 retail customers in Louisiana and supplies wholesale power in Louisiana and Mississippi. Its legacy RTU upgrade has become routine for Miles Dupuis, a principal engineer at Cleco with 20 years of experience in SCADA equipment and 33 years total at the utility.
|Substation remote terminal unit (RTU) installation after upgrade.|
“There is no comparison (with a full RTU replacement). Using a vendor that allows us to retrofit RTUs in one day while using only one person in the field is far less costly than what other vendors offer,” Dupuis said. “Some solutions offer the option to replace old, outdated RTUs with replacements to modernize your substations; however, it usually takes three people and two to three days to complete the task, at a much more significant cost.”
Xcel Energy is also discovering how simple, fast and cost-effective an RTU upgrade can be when compared with a full replacement.
“We now have the ability to modify aged RTU designs that have little to no replacement parts into a modern RTU,” said Mitchel Wilkinson, an Xcel Energy engineer in Minneapolis with seven years of substation engineering and design experience. “This solution leaves all existing wiring in place while upgrading CPUs so that data can be gathered and sent, using modern communication protocols. These modifications can be done for a fraction of the engineering and construction time required for a complete replacement. This is a great option as we upgrade our aging system.”
The Future is Today
Technology constantly evolves and infinitely more possibilities will exist tomorrow than exist today. New features and products should never exist, however, only for the sake of creating something new. They must provide answers to real concerns, challenges and problems.
The legacy RTU upgrade is a solution to a real problem. It can, in many cases, be a better choice than RTU replacement when modernizing the substation control center. It addresses the three major constraints utilities face: budget, time and people.
Miguel Bengla is substation automation product manager at Advanced Control Systems (ACS). He has been working in substation management for 10 years.