Advanced Practices: Emerging trends in O&M of TPPs

The role of thermal power plants (TPPs) is changing at a fast pace wi­th the shifting fuel mix, led by the in­creasing share of intermittent renewable energy sources. TPPs, which have been the ma­in source of baseload power in the past, are now increasingly expected to play a supportive role in the grid. Be­sides this, stri­ct environmental nor­ms and ageing th­er­mal plant fleets have ad­ded to the cha­llenges on the generation efficiency and power plant availability fronts. It is, th­erefore imperative for gencos to adopt advanced operatio­ns and maintenance (O&M) practices to align with emerging trends and requirements, and ensure efficient and uninterrupted operations. To this end, the deployment of new and innovative digital solutions such as digital twins, ind­us­trial internet of things, artificial intelligence and ma­chine learning is gaining traction at TPPs. Develo­pers are also de­p­loying data analytics tools to improve cyclic eff­iciency throu­gh the detection of energy losses.

Need for O&M

With growing penetration of renewable energy in the power mix, TPPs are re­quir­ed to undergo several rounds of load cycling by quick ramping up and ramping down of their operations. In view of plans to meet 50 per cent of the country’s energy requirements by 2030 throu­gh renewables, thermal utilities will be required to run their plants at technical minimum levels, though these were originally designed for baseload operation. Cycling and part-load operation of TPPs close to technical minimum levels leads to thermal stress, component de­te­rioration, poor heat rate and increased auxiliary power consumption, resulting in higher opex and outages, and consequent revenue loss. Improved O&M pra­ctices such as real-time asset monitoring, along with data and predictive analytics, can help gencos mitigate these is­sues and ensure higher efficiency as well as cost savings.

Moreover, TPPs need to comply with stringent emission norms, especially considering the introduction of a penalty mechanism for non-compliant operations, which require operators to overhaul the existing pollution control systems. In addition, installation of new equipment such as flue gas desulphurisation systems and nitrogen oxide control systems will increase the capital and operational expenses of utilities. In or­der to maintain efficient plant operatio­ns in the emerging scenario, it is im­pe­rative for gencos to implement effective O&M strategies.

With the ageing of TPPs, utilities need to invest in renovation and modernisation (R&M) for efficiency improvement. R&M can help utilities achieve an increase in generation of about 30 per cent and an efficiency improvement of up to 23 per cent. While the addition of 1 MW of generating capacity requires a capex of around Rs 60 million per MW, an equivalent capacity can be achieved by investing around one-third of this amount in R&M activities.

Best O&M practices

Most TPPs are being required to operate under minimum technical load because of the increasing integration of renewables. In order to maintain performance at low load, the use of secondary air da­mper control tools is gaining promin­ence. It helps in getting the best mill co­mbination and maintaining an optimum boiler temperature. Optimisation of burners, reduced mill operation, app­lication of advanced process control and predictive analytics, and enhanced digitalisation for boiler and turbine feed mo­nitoring are useful to maintain plant performance during flexible operations.

The heat rate of a power plant is a crucial metric that directly affects the profitability of a firm. Heat rate degradation is ca­used by high energy drain valve passage, and therefore, it must be monitored frequently. Optimisation of cooling tower fans, cleaning of condenser tubes and monitoring the terminal temperature differential of heaters at regular intervals are being undertaken to improve the heat rate. One of the essential procedures at the fuel level is pile age monitoring, whi­ch helps decrease heat loss and maximise heat value utilisation. Further, ad­vanced coal blending techniques are being un­dertaken to make the most efficient and cost-effective use of the fuel.

The use of gamma rays is gaining traction for monitoring emission assessing, assess electrostatic precipitator hopper emptiness and scheduling maintenance accor­dingly. Exfoliation meters are being used to monitor the deposition of oxide layers in coils. In order to identify metallurgical fl­a­ws, a small oil igniting system and a ph­a­sed array of ultrasonic tests are be­ing used. Further, an oxygenated treatment cycle chemistry programme can help de­crease corrosion and iron carryover. Some of the other O&M practices that are increasingly being deployed include furnace mapping to evaluate boiler com­bustion and manage the furnace outlet temperature; deployment of eq­ui­p­ment changeover tools to undertake scheduling of changeovers in accordance with SAP; cross-checking the air preheater intake for oxygen and carbon monoxide with a potable gas analyser for combustion optimisation; and the use of boiler tube leakage management, smart soot blowing, and insulation surveys of critical piping and furnaces.

In order to enhance the operational efficiency at a power plant, a strategy of maximal mechanisation with minimal manual work needs to be adopted. Elec­tric im­pact wrenches, electrically powered 2T gan­try cranes, electric-operated rotor st­an­ds, portable plasma cutting ma­chines, battery-operated pick- and -ca­rry cranes, or Teflon wheel-mounted fab­ricated trolleys are some of the examples of mechanisation. Apart from this, utilities should target and enhance key operational are­as, while outsourcing non-important sectors to business partners that adhere to stringent key performance indicator mo­nitoring. Inventory management should be implemented using vendor-managed inventories and an annual rate contract for fast-moving items.

Emerging trends in O&M

In recent times, new and innovative technologies are gaining popularity for efficient O&M. For instance, data analytics, machine learning and artificial in­telligence are being used to track op-erating parameters for early detection of excursions or defects. Utilities are de­p­loying da­ta analytics tools for impro­vement of cyclic efficiency through de­te­ction of en­ergy losses. These tools op­timise the ma­in­tenance strategy by res­tricting unsche­duled outages and eliminating unnecessary preventive maintenance. Equipment health monitoring is being undertaken through real-time monitoring of critical parameters and condition monitoring.

Utilities are also undertaking reliability-centred maintenance (RCM), which fo­cuses on improving the reliability of po­wer plants by providing insights on risk versus cost for the maintenance of a particular equipment. RCM employs pre­ve­n­tive maintenance, predictive ma­inte­n­ance, real-time monitoring, reactive ma­in­tenance and proactive maintenance techniques in an integrated manner to increase the probability of the functioning of a machine or equipment in a req­uired way that enables increased equipment availability, and reduces maintenance and resource costs. RCM focuses on reliability instead of availability. It fo­llows a proactive approach to prevent failures, as compared to a reactive app­ro­ach. RCM uses real-time data for analytics and predictions and identifies interventions for reliability improveme­nt. It sends automatic notifications to the engineer when the health index crosses a certain threshold.

A robust maintenance strategy is based on root cause analysis of various kinds of equipment, generation loss and mean ti­me before breakdown, thus optimising O&M. Based on the severity, frequency, detection rating and financial impact of the failure, failure modes and effects an­alysis of equipment is being perfor­med. For essential equipment and operations, a zero-forced-outage plan is being developed. A preventive maintenance prog­ramme based on the equipment category is gaining traction, alongside stro­ng condition-based maintenance.


In order to adopt an optimal O&M strategy, power plant operators need to un­dertake a thorough techno-economic analysis to identify the best-suited technology/solutions, as certain measures and technologies can entail significant capex, while others may be carried out through minor modifications. For this, increased operational expenditure on account of a higher heat rate, wear and tear of components due to cycling, and oil consumption for frequent start-ups also need to be factored in.

Adopting effective O&M methods has be­come essential in the coal-based po­wer generating segment, given the constraints of a shifting fuel mix, flexible op­eration and tougher environmental and safety requirements. Employing the best O&M pra­ctices at TPPs not only help in achieving high levels of performance, but also maintain the health of the po­wer plant equipment. Going forward, the adoption of O&M strategies and ass­ociated digital solutions is expected to pick up to ensure sustainable operations of gencos in times to come.