Digital control not only increases efficiencies in power stations, but brings tighter environmental control and lower overall costs. As the 'brains' of the modern power-generation facility, an integrated, digital control architecture is integral to providing power producers with the necessary insight into equipment and processes on not only a unit or plant level, but across an entire fleet. Armed with this insight, power producers are able to make informed decisions about how best to manage competing environmental, operational and financial objectives.
The introduction of intelligent field devices and digital bus technology in more recent years represents another step forward for the industry. With these technologies and the wealth of data they deliver, plant-wide asset management systems have become an integral part of the digital plant architecture, allowing power generators to proactively – rather than just reactively –respond to changing plant conditions. Wireless technologies are only driving these capabilities further.
Emerson, with its PlantWeb® digital plant architecture, is one of the leading suppliers of digital automation solutions to the power generation industry. The company's vice-president of sales and marketing, Bill Brownlee, discusses the latest developments in digital control, the advantages they bring to power generators and where the technology is headed in the future.
Mitch Beedie: How do you think overall digital control has progressed in the last few years?
Bill Brownlee: The introduction of a digital bus-based control and automation architecture – which consists of high-speed communications networks, intelligent field devices, asset management software and bus I/O technologies – has been a step change for the power generation industry.
At the time Emerson formally introduced its PlantWeb digital architecture to the power generation industry, it had already been proven in a number of process industries including chemical, pulp and paper and oil and gas. Despite its successful track record the power generation industry was initially cautious about adopting this approach.
How did you overcome this cautious approach by the industry?
This was not unexpected, as traditionally, the industry has been slower to adopt new technologies due to the criticality of the power generation process. However, in just five short years the tide has turned, as power generators have become more aware of the benefits these technologies provide. For example, during the plant construction and start-up/commissioning phase, these technologies help lower wiring costs and streamline device installation, communications verification and troubleshooting. Over the long term, the wealth of information made available by digital bus-based technologies and intelligent field devices can be used to optimise plant operations and maintenance activities, as well as avoid costly unplanned outages.
Now, the majority of new units Emerson has been selected to automate around the world are deploying digital bus-based technologies.
What are the latest developments in digital power plant control?
The next technological revolution that will impact plant performance is wireless – a technology that will have further implications on reliability and availability. A wireless solution cost-effectively extends the full benefits of a digital bus-based plant architecture to locations that were previously inaccessible. Going wireless can eliminate the need for drilling through concrete decks, installing conduit and cable trays and pulling wires.
Even more importantly, data from wireless devices can be seamlessly integrated into the control system, offering insight into additional plant and process data for control and asset optimisation. This translates into further operational efficiencies and performance improvements.
How do you envisage wireless being used in the power plant?
Wireless devices employ self-organising mesh networks in which each device can act as a router for other nearby devices, passing messages along until they reach their destination. If there is an obstruction, transmissions are simply re-routed along the mesh network until a clear path to the gateway is found.
As conditions change or new obstacles are encountered in the plant, such as temporary scaffolding, new equipment or a parked construction trailer, these wireless networks simply reorganise and find a way to deliver the data. All of this happens automatically, without any involvement from the user.
Is the size of implementation an issue with wireless?
From an implementation standpoint, wireless is flexible and scalable. Power producers can adopt this approach wherever it makes sense for their plant. By picking an application – even a small one – users can achieve improvements that would not be possible in a traditional plant configuration.
Overall, how advanced is the technology today?
Power generators are just now beginning to implement this technology. Applications include monitoring pressure relief valves, monitoring the corrosion in pipelines and vessels, monitoring temperatures at pre-heaters and pumps in order to improve thermal efficiencies, and freely deploying vibration analysers – even when the equipment itself is rotating. As was the case with digital bus-based technologies, the use of wireless will steadily increase as the power industry becomes better acquainted with the benefits this technology offers.
Emerson has been winning a notable amount of contracts for its digital automation of power plants in recent times. Where are you finding the strongest market demand?
Emerson is installing its PlantWeb digital bus-based architecture based on the Ovation expert control system at numerous new coal plants being constructed around the world.
The US has been a strong market: Emerson is deploying digital bus-based technologies for the majority of the 17 new coal-fired plants it is automating in the US alone. These plants will go into commercial operation within the next few years to help meet the country's growing demand for power. Emerson control systems are already installed in plants representing more than 350,000MW of generating capacity in the US.
The Asia-Pacific region, in particular, has been booming, as countries focus on building the electrical infrastructure needed to support their burgeoning economies. Emerson has won contracts to install its automation technologies at approximately twenty 1,000MW units in China alone, many of which are utilising digital bus-based technologies to monitor and control critical processes and equipment.
What are the main advantages of adopting a digital bus-based architecture for existing power plants?
Greater reliability, availability and profitability. The technologies of a digital automation architecture work together to provide valuable, actionable insight into plant operations. Smart devices such as transmitters and actuators can measure and report more than one variable from the process, while also providing that data at much higher resolution than possible with conventional field devices.
By constantly performing self-diagnostics and reporting on their health, they have become part of a powerful asset management system that alerts operators to emerging problems before they impact the process.
Consequently, power generators are able to proactively – rather than just reactively – respond to changing plant conditions. Over the long term, the wealth of information being delivered from the digital bus can be used to optimise plant operations and maintenance activities, as well as avoid costly unplanned outages.
Simply put, smart devices and digital bus technologies are two of the most significant advancements in the industry's ongoing quest for improved plant reliability and availability.