Finely tuned

The increasing demand for high efficiency, low emission power generation technologies is driving an evolution in power plant control technology. While control systems become increasingly robust and complex, market forces are driving the convergence of plant control and asset management.

Siàƒ¢n Green

“With economic growth strong and electricity demand growth high across [Asia], the pressure to deregulate in order to provide infrastructure and investment is strong,” said Roy Adair, CEO of Singapore’s Senoko Power, at Power-Gen Asia last month. GE’s Magued Eldaief, who spoke of the combined pressures of a growing world population, fuel sourcing complexities, environmental requirements and escalating security concerns, echoed his vision of the pressures faced by the industry.

According to the US Department of Energy, the world’s population will grow by 20 per cent by 2020, while energy consumption in the same period will double. World net electricity consumption is forecast to double from 14 275 billion kWh in 2002 to 26 018 billion kWh in 2025. Some 59 per cent of the projected growth in electricity demand will occur in emerging economies, where electricity use will increase on average by 4 per cent per year from 2002 to 2025, compared with 2.6 per cent per year worldwide.

This demand translates into capacity additions of 75 GW annually worldwide for the next 20 years. Coal and natural gas are expected to remain the most important fuels for electricity generation, accounting for 70 per cent of capacity additions and just over 60 per cent of the energy used for electricity production in 2025.

Capacity demand, environmental considerations, fuel price and resource issues as well as deregulation are in turn driving demand for higher efficiency in power generation and consequently more advanced power generation technologies. This trend is seen in the development of highly advanced gas turbines, supercritical and ultra-supercritical coal fired power plants as well as improved renewable and distributed generation technologies.

According to Samir Pandya, business development manager of Emerson Process Management, China is a case in point: the country is power hungry and focusing on the addition of new nuclear and fossil-fired capacity. New coal plant in the country is predominantly supercritical or ultra-supercritical, for example the 2 x 1000 MW Yuhuan ultra-supercritical plant currently being developed in southern China.

While there is no clear definition of ‘ultra-supercritical’ conditions, they are generally taken to mean supercritical pressure and main and reheat steam temperatures of about 600à‚°C. Siemens can today supply steam turbines capable of operating with maximum steam parameters of 300 bar/600à‚°C main steam and 620à‚°C reheat steam. “The thermal efficiency of this cycle is 51 per cent,” says Dr. Andreas Wichtmann, steam turbine product manager at Siemens Power Generation. “This gives a net efficiency of 46 per cent. The outlook for the future ࢀ¦ is the 700à‚°C power plant which gives a thermal efficiency of 56 per cent or a net efficiency of 51 per cent. The realization of a test unit operating at the conditions is to be seen beyond 2015.”

The use of advanced materials and designs are therefore helping operators to push the efficiency boundaries in power generation and meet the challenges of the market. However they are also placing pressure on power plant control systems to be more robust and accurate than ever before to help power generators optimize operation of the plant.

“In today’s market, operation of advanced technology means more risk,” says Michael Chilton, president and CEO of GE Energy Control Solutions. “The consequences of equipment failure or error are high, both in terms of the safety of people and in financial terms. Equipment failure can leave a power plant – a highly valuable asset – not generating for several weeks or even months.”

Control solution providers must therefore accept that the increasing use of advanced power generation technologies puts an additional burden on plant control systems, and they must adapt their systems accordingly, says Chilton.

This view is echoed by Pandya of Emerson Process Management, whose Ovation control solution is to be installed at the Yuhuan plant in China. “High availability and precise control systems will protect operators’ investments. While the Ovation control system itself has not needed to change due to the use of advanced power generation technologies, the control applications on it has.”

Power plant challenge: handling different data sources and formats. Source: Siemens
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Specifically, some of the functions of Emerson’s SmartProcess advanced control and optimization software have been embedded into the Ovation distributed control system (DCS). Using fuzzy logic, neural networks and model-based predictive controls, SmartProcess identifies the precise control settings for continuous optimal performance, and incorporates self-learning features that enable it to adapt to long-term changes in the plant. In doing so, plants are able to balance conflicting objectives – for example, achieving lower NOx levels while improving boiler efficiency.

“For example, sootblowing is one of the main control applications that needs to be tightly controlled in these advanced coal-fired plants. It is a non-linear application that SmartProcess handles quite well,” says Pandya. “Such applications are becoming standard features of the DCS in order to support the complex operational goals of power plants.”

According to Pandya, on a larger scale, fleet-wide optimization multiplies the value of this information by facilitating the exchange of real-time data among corporate offices, regional plants and individual operating units, allowing plant owners and operators to make better and more informed decisions regarding fleet deployment.

Another key feature demanded by operators today is an open platform. “The days of proprietary closed systems are gone,” says Chilton. “Operators need to be able to integrate and add loops from various manufacturers. Scalability is also critical as many operators want to take an incremental approach to the DCS over time to fit their budget needs.”

Chilton’s comments give clues to GE Energy’s approach to plant DCS products as it prepares to launch its power plant control product range. The launch – planned for early 2006 – will make GE a DCS provider, filling a gap in the company’s considerable power industry product range. The DCS product was acquired in March this year when GE bought a majority share in China’s Xin Hua Control Engineering Co. Ltd.

GE plans to take Xin Hua Control’s platform – which has been widely deployed across China – and market it across the world. However, Chilton is aware that competition in the DCS market is strong and that GE must be able to differentiate itself to stand out above others. “Operators today need much more than the ability to just start and stop,” says Chilton. “They need data and analytics to help them optimize their assets as well as on-line information such as spark spread and predictive maintenance.”

GE recognises that today, many utilities want to transfer plant operational data into their ERP system in order to get a total picture of their assets and manage them accordingly. “In this sense we are seeing a convergence of plant control and asset management,” comments Chilton. This convergence is occurring mainly in deregulated, competitive markets such as Europe and the USA. Other markets are less profit-orientated and continue to focus on reliability, says Chilton. “So geography plays an important part, and the DCS needs to be flexible.”

Integration of plant control systems with ERP is already taking place in the power sector. According to Andreas Schimanski, general manager of IT power solutions at Siemens Power Generation, the challenge for power generators today is to collate and analyze critical information that is distributed among different databases, files and applications, and to make sure that this information is available to the right individuals for decision-making purposes. With this in mind, the company has developed Cockpit, a power plant information system that integrates plant control technology with other software systems such as ERP systems to create a uniform work tool for the business.

“Complex calculation models process data from all the systems making it possible to get a clear and comprehensive picture of the plant’s status and its possibilities at any given time,” said Schimanski. “Cockpit provides reliable information on availability and generation costs, generates forecasts on load capability and demand, and even provides market and contract data.”

According to Siemens, the integration of plant control systems with ERP systems provides utilities with several benefits, including the facilitation of company-wide fleet management and production control, and the creation of cross-site strategic plans for fleet expansion and maintenance measures. The transparency created through system integration helps to generate best-practice sharing and standardized benchmarks.

The first Siemens Cockpit system has been installed at Guohua Electric Power Corporation (GEPC) in China, where data from three power plants is assessed at the company’s headquarters in Beijing. The system will eventually be used across the company’s entire fleet of 14 power plants. “The Cockpit provides a holistic overview of the performance of the company’s power production business, from energy demand to power output and from maximum load to production costs,” says Schimanski.

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