There are several hundred peaking power plants in the US equipped with OEM gas turbines. Operators of these plants face an aggravating inability to diagnose and correct system issues due to the tightly closed architecture of the original control system. Facility owners have long been interested in a more-open system that would enable them to view live system data and quickly respond to process issues. Owners and operators of OEM gas turbines are now facing the decision of how best to upgrade their turbine control systems, and should realize they have new options in the form of third party, open systems. These solutions provide the owner/operator with the tools and data necessary to become a self-maintainer: troubleshooting, tuning, repairing and improving independently.
Read more on the case for an open control system here
Here are the top three questions I hear when asked about turbine control system retrofits.
How does a turbine control retrofit investment compare to buying a new turbine?
Revitalizing an older turbine control system with a mechanical overhaul is a less expensive path compared to buying a new turbine. Some situations may require replacing an existing turbine. Plant owners should consider the past performance of the unit, the annual maintenance costs and fuel efficiencies. A new turbine may offer higher heat rates, better emissions and overall more MW output than older systems; however the return on investment for a new turbine would take many years to recover. With a newer control system, opening the code to the owner, adding instrumentation, and expanding the I/O provides more flexible operational options than operators previously had. A new control system on an older unit allows the flexibility to add redundancy in I/O, a communication network and controllers thus ensuring the reliability of the unit will not be faulted by the control system itself. Operational awareness is increased by features such as monitoring areas, alarming and informational items allowing operators to report degradation of the unit so that preventative maintenance can be done to maintain availability.
What is the typical lifetime extension of a standard turbine?
It is difficult to put a number to the years of added life. Some PLCs (such as those used to control a turbine) have limited support, and once installed, they are no longer supported and need to be replaced in a matter of 12-15 years. As technology continues to improve at a very fast pace, the installed system can quickly become obsolete. ABB’s philosophy of “Evolution without Obsolescence” provides a control system for the life of the asset. As I/O modules improve, controller speeds and memory increase, the same logic that was delivered for the control system can be reused with the newer hardware. ABB R&D develop the next generation of modules with this in mind. A customer can replace the older version of the I/O or controller with the latest version as they deem necessary. For over 30 years some plants are still operating older INFI 90 DCS platforms and simply replace I/O modules as needed with the latest Symphony® Plus offering. Once a customer invests in the architecture, the future costs to maintain is easily done within an operational budget without the need for a control system rip-and-replace capital expenditure.
Do you perform audits to assess the feasibility of having this done at my plant?
Great question! ABB has vast experience on a number of different turbines. You can contact the ABB office and we'll get you in touch with a local sales rep who will help get the appropriate person assigned to conduct an audit. We'll provide you with a report of findings and outline the ABB DCS offerings that will get you the most reliable system for your needs.
If you have more questions about a turbine control system retrofit and how it might help you improve performance and productivity in your facility, I'd be glad to try to answer them.
Kevin Kochirka is a Consulting Application Engineer with ABB Inc. Process Automation Power Generation business. Mr. Kochirka is responsible for the development, enhancement and delivery of the Combustion Turbine Control System. Kevin has a BS degree in Electrical Engineering Technology and has over 25 years of experience with combustion turbines as a Controls Engineer, Project Supervising Engineer, and Field Service Commissioning Engineer. His experience is on various models of combustion turbines (ABB GT11s; GE Frame 5 & 7; Westinghouse 191, 251, 501; Siemens V84.2; Pratt & Whitney Power Pac and Twin pac FT4 and FT8 engines; and Rolls Royce Avon units).