Towards Digitalisation

Advances in BTG equipment to improve generation efficiency

Digitalisation is gathering momentum in the power generation industry as more companies realise the need to upgrade conventional power plants to meet the emerging market requirements. A digital power plant offers efficient and cost-effective power generation, reduces maintenance expenses and enables quick load adjustment. This gives such plants an edge over traditional power plants. Digitalisation can bring flexibility in power plant operations to accommodate the growing renewable energy sources, along with keeping a check on emission and water consumption levels with an advanced tracking system.

Drivers

Globally, companies are launching digital initiatives that encompass not only critical assets such as boilers, turbines and generators (BTGs), but also smaller balance of plant systems that can significantly influence plant operation.

The digitalisation of BTG equipment in a power plant entails the use of sensors, actuators, digital controllers and supervisory computers. With the use of feedback control loops, plant processes and performance can be monitored and appropriate control actions can be taken to maintain optimum conditions despite system disturbances such as changes in coal quality or load demand. With the use of analytics and information and operational technology solutions, meaningful insights can be derived from operational data, and corrective measures can be taken to maintain plant performance, reduce unplanned outages and downtime, and extend the operational lifetime of assets. With digitalisation, power plant operations can be remotely monitored and modified based on performance parameters. Further, remote monitoring and external support can address key human resource and knowledge retention issues.

The growing share of renewable energy in the power generation mix requires flexible operations of conventional power generation assets. Besides, conventional power plants have to operate at a lower plant load factor to accommodate renewable energy sources. With digital solutions that provide an enhanced view of a plant’s health, operators can get a clear sense of asset flexibility. Asset performance management during cyclic and flexible loading is one of the key benefits of power plant digitalisation. The use of sensors in various BTG components helps in closely tracking plant performance. The data gathered from these sensors can be used for improving the operation of power assets and reducing expenses. It is transformed into actionable intelligence by combining robust analytics with domain expertise, thereby moving from reactive and preventive maintenance to predictive maintenance. Further, with historical forensic analysis, anomaly detection and asset condition monitoring, the life of the machine and equipment can be prolonged.

Further, the increasing cost of complying with environmental regulations is creating additional operational complexity and straining operating margins. Digital solutions can support and facilitate this transition through asset optimisation strategies that take into account emissions, abatement costs and equipment life.

Digital solutions in BTG

The deployment of digital solutions in power plants can help in addressing several issues and challenges pertaining to plant performance. Sensor data gives the ability to predict plant performance, evaluate different scenarios, understand trade-offs and enhance efficiency.

One of the digital solutions adopted at power plants is the blade vibration monitoring system (BVMS). It prevents last-stage blade failure in turbines, which occurs as a result of electrical corrosion, corrosion fatigue, stress corrosion, water corrosion and equipment fatigue caused by material quality issues, load variation, etc. BVMS tracks the performance of turbines and helps in improving plant availability and reducing unplanned shutdowns.

Another digitalisation solution useful in the power generation segment is 3D printing, which helps in maintaining spare readiness with additive manufacturing. Minimising the lead time for spare part manufacturing is particularly important, since a loss in generation time would translate into a significant financial loss. The 3D printing of spare parts significantly reduces the lead time needed for spare part manufacturing. Besides, it is cost effective, easy to revise and easy to use.

A useful digital solution that facilitates flexible operations of the plant is condensate throttling. It provides quick-response load change capabilities. Full condensate throttling helps quickly increase the power output by up to 7 per cent. When the condensate water control valves close, the demand for low pressure heaters reduces and thus extraction steam has to pass through the last turbine stages, thereby increasing the turbine power output. In September 2017, a condensate throttling-based primary frequency control solution was commissioned at NTPC’s Dadri thermal power plant  (Stage 2, Unit 6). Meanwhile, an acoustic steam leakage detection system can help track steam leakages in boilers. In each zone of the boiler, sensors are installed on a sonic tube, which penetrates the boiler casing and terminates at the edge of the boiler water wall tubing. In case the sound of the steam leak exceeds a preset limit, an alarm is raised to the registered contacts.

Another way to digitally operate a plant is by creating its digital twin, which is an organised collection of physics-based methods and advanced analytics used to model the present state of every asset of the plant. The digital twin is used to execute “what if” scenarios and drive outcomes based on analytic models that mirror and predict the functions of the physical assets. The digital twin uses algorithms and models of artificial intelligence to predict the future performance of the plant. These models are continuously updated to accurately represent the “present” state of a plant. Using the digital twin models and state-of-the-art techniques of optimisation, control and forecasting, the applications can accurately predict outcomes along the axes of availability, performance, reliability, wear and tear, flexibility, and maintainability.

Conclusion

As per a 2017 report by technology and consulting firm Capgemini, utility companies are significantly investing in digital enhancements for coal-and gas-fired energy generation in order to increase production efficiency and reduce their generation costs. Over the past five years, firms have invested an average of $330 million in digitalising their power plants. Continued investments will see one in five power plants (19 per cent) becoming “digital plants” by 2025, operating at approximately 27 per cent lower costs, and together contributing to a 4.7 per cent reduction in global carbon emissions from power generation. The report, which surveyed utility leaders across China, France, Germany, India, Italy, Sweden, the UK and the US, found that increased production efficiency due to digitalisation will enable utilities to bring down energy generation costs.

However, while the opportunity in the segment is immense, it has largely not been realised, as data from various sensors has not yet been integrated to provide a more comprehensive view. When such data (both real time and historical) is collated in meaningful combinations, operators and fleet managers can derive significant additional value from it.

To conclude, the digitalisation of operations is essential to maintain the competitiveness of conventional power plants going forward. However, to leverage the benefits of digitalisation, the developers must utilise the plant performance data in every possible way to predict the future scenarios and enhance efficiency. Also, digitalisation makes utilities more vulnerable to cybersecurity attacks. Utilities will, therefore, need to proactively manage risks that data and physical assets face, and adopt best practices to keep systems secure and up to date. Going forward, as utilities decide which digital solutions to invest in, they will also need to review their organisational and technical capabilities and identify the right technology partners.

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