The Indian wind power segment has been facing major challenges, particularly in the area of operations and maintenance (O&M). A key problem is the financial distress of original equipment manufacturers (OEMs), which is leading to delays in accessing valuable data. This, along with spare parts unavailability, impacts power generation and revenues for plant owners. Moreover, compliance with the forecasting and scheduling regulations across states is cumbersome. To eliminate these bottlenecks and the overdependence on OEMs, the wind industry is looking at alternatives and deploying advanced monitoring systems. At a recent webinar organised by Renewable Watch on “O&M of Wind Power Plants”, industry executives discussed the key issues and solutions to address these challenges. Edited excerpts…
The Indian wind power segment is facing problems that are akin to the rest of the world. However, one aspect that is peculiar to the country is the dominance of OEMs. We can compare it with North America, which has a very buoyant service market with a lot of independent service providers providing alternative services to OEMs. Many refurbishment jobs are also available that are catered adequately by spare parts availability. This is not the case in India. However, advanced technology can solve all these challenges with a very long lead time in terms of diagnostics. This can help with spare parts availability as with the help of diagnostics it can be predicted which components would fail in 12 to 18 months. This gives sufficient time to source alternative components and reduce plant downtime.
Unfortunately, we have seen a few cases of bankruptcy in the past on the OEM side with the most recent being Senvion that left a lot of owners stranded because they did not have access to data and could not operate their turbines any more. Thus, often investments in advanced technology are also a way for de-risking future operations. Many Indian wind power plant owners have already implemented various digital technologies for diagnostics. While some are standard practices such as SCADA, a few are more advanced such as electrical monitoring. It is very important to look at owners’ returns on investments, the blind spots and assess how technology can minimise the risk exposure. There is very little discussion on the life extension of wind assets in the Indian wind space. The data we can collect now will help going forward. Right now, most of the efforts are concentrated on the monitoring of the gearboxes. Going forward, pitch bearings and blades are going to be the next blind spots as turbines age, and it is important to focus on their diagnostics as well.
Over the past three years, we have witnessed a trend where the forecasts that people use for their financial models have been increased from 20 to 35 years. Thus, a focus on life extension of wind power plants is important and should be a priority for wind asset owners. However, often we see people starting too late. For instance, plant operation life of 15 years or less might seem optimum in terms of planning and collecting enough information about structural elements. It might be a better idea to start this process earlier as components such as gearboxes can be replaced timely and project life can be visibly extended. Often, not much attention is given to replaceable components such as lubrication systems and sensors if the structure keeps operating. However, delaying the replacement of these components can significantly impact life extension and associated costs.
In Europe and North America, people focus more on the integration of different monitoring systems, which gives greater visibility, saves resources and improves the accuracy of prediction. Thus, the next step is to integrate various data sources as a lot of data can get lost owing to different uncoordinated monitoring systems.
NTPC is known for its thermal power generation; however, in the past few years it has managed to carve a place for itself in the renewables space as well. We are mainly active in the solar segment, although we have a presence in the wind segment too. Currently, we have about 25 machines of about 2 MW each, which adds up to a cumulative capacity of 50 MW. This capacity is located at an Inox wind farm in Gujarat in which NTPC has a stake. NTPC is taking various steps to make its energy portfolio greener by adding significant capacities of renewable energy sources. By 2032, the company plans to have a minimum capacity of 32,000 MW through renewable energy sources constituting nearly 25 per cent of its overall power generation capacity.
The major challenges that we are facing include the dependence on OEMs for O&M functions. The machines we own are located within a large farm owned by another party. Thus, maintenance of not only the machine but also of the line and substations becomes complicated as some of the maintenance activities are beyond the generator’s scope. In the wind power segment, there are very few service providers when it comes to OEMs. Further, the availability of spare parts is very specific to OEMs. There is also the issue of forecasting and scheduling. Scheduling is done at the pooling station level and at that pooling station, machines of multiple generators are connected. If there is a deviation settlement mechanism charge, it is borne by the generator and not the entity responsible for operating the grid substation. Thus, the OEMs do not bother to change the available capacity or communicate effectively regarding the actual generation of the plant to change the schedule.
Our machines are relatively new and have been in operation for the past three years. We have a long-term O&M contract under which there is a guarantee from OEMs regarding a certain percentage-based plant availability. We have not directly entered the O&M space as that part of the responsibility lies with the OEM for the plant. From NTPC’s side, there is limited involvement in the O&M of the wind plant as the machines are relatively new and no issues in terms of availability have been faced yet. However, NTPC is involved in the performance monitoring of each machine. There is a central monitoring centre/system where we monitor the machine performance on a regular basis and also have algorithms for finding out the optimum generation depending on wind speeds during the day. We have some set parameters against which we assess performance and coordinate with the OEM in case there is any deviation.
Bharath Kumar Narilla
For wind farms, the weather conditions in each domain are unique. For instance, Rajasthan has a desert environment, Gujarat has a coastal as well as dry environment, Maharashtra has a coastal and humid environment, then there are dry areas in Karnataka and high ambient temperatures in Andhra Pradesh. Such varied conditions call for the upgrading of the turbine to suit multiple environments. Other than regional weather conditions, there are grid challenges, which are unique to each state. Such concerns keep posing challenges to the operating team in terms of maintaining grid reliability and safeguarding turbine components. In India, the real challenge exists in upgrading knowledge, skill and competency in understanding turbine components better.
The wind segment in India is focusing more on availability and reliability, although we also need to look at the best practices being adopted by the wind industry. Practices are evolving and undergoing transformation – for instance, drone inspection of blades is being widely done to inspect the main rotating and power generating components. This also helps in understanding the aerodynamic profile of blades and in implementing reliability measures. Along with forecasting and scheduling, operating performance is improving across the country. Further, there is a transition towards predictive analysis and condition-based maintenance practices.
The two main strategies adopted by the industry are reactive approach and proactive approach. The quality and performance of the asset largely depend on these. An appropriate and adoptable solution must be worked out depending on the operating model of the asset as well as the service need. The industry is now going to experience an ageing fleet. Thus, there are growing concerns to identify the need for part replacements, upgrades, minimising downtime, life extension programmes and disposal of components. The industry needs innovative solutions for the maintenance of gearboxes, generators and other components with a focus on the utilisation of SCADA and turbine controls.
The challenges we face in the O&M space are on account of OEMs. Many OEMs are not doing well financially and this impacts our operations. Therefore, we have started moving towards other alternatives. Another key challenge is the availability of spare parts especially from OEMs that are not doing well. When there is a failure of a critical component, we have to often wait to replace it because the component is not always available with OEMs. This leads to major delays in the replacement of critical components leading to huge losses. In Rajasthan, we have faced issues of blade tip erosion because of sandstorms and this has led to a loss in wind generation. We have to repair such blades frequently. With the ageing of wind assets, we are also facing challenges related to updates and upgrades of SCADA systems. Another key challenge is with respect to forecasting and scheduling as strategies and policies are different across India.
To improve the operational efficiency of wind assets we use central monitoring systems. We have also incorporated artificial intelligence (AI) in our O&M practices. The performance of each turbine is monitored on a daily basis, issues are analysed, then guidelines are passed on to respective site managers to take corrective actions. Also, regular feedback is taken on the issues observed by site managers. These issues are incorporated in the AI and machine learning (ML)-based systems.
We have not yet moved towards condition-based monitoring. As of now we are only using preventive maintenance. Under this, O&M is scheduled at fixed intervals and based on alarms and data, corrective measures are taken. Having said that, we are open to the idea of using sensors and transitioning towards condition-based monitoring. Going forward, we would like to reduce the cost incurred on forecasting and scheduling of wind power and are interacting with various state governments on the same. We have started a pilot project under which we are engaging with a forecaster to gather forecasting data for all our assets. Then, we compare it with the Central Electricity Agency’s forecasts and do the necessary updates. As an IPP and asset owner, we need to find ways to reduce the penalties arising from our end. We are also interacting with various OEMs to improve the efficiency of our wind turbines. In a few regions we have noticed that by using vortex generators we could improve efficiency by 1-2 per cent. Similarly, there are discussions around improving yaw misalignments. Overall, the focus area for us remains reliability of assets which depends on the quality of preventive and predictive maintenance. This, in turn, improves the revenue from assets. The use of innovative technologies in the market is another focus area as this also increases the revenue from wind power projects.
The various challenges that we face with our wind assets are determined by the age of the fleet, the technologies employed, the regulatory environment, and the location. Moreover, with the average age of the fleet being around 10 years, obsolescence is a critical issue to deal with, especially with SCADA that needs upgrading. With regard to regulatory challenges, for example, the new Supreme Court order to move transmission lines underground, many of CLP’s projects with 33 kV lines will need undergrounding, necessitating high unplanned capex. Further, states have specific requirements for forecasting and scheduling. One way by which CLP minimises deviation settlement mechanism penalties is by installing meters at pooling substations. However, there are challenges when the developer doesn’t fully own the entire common infrastructure such as substations. Older wind farms were built with a lot of common supporting infrastructure. In many cases, even feeders are not dedicated, and hence, installing meters and sending the required data to the qualified coordinating agency in a timely fashion requires agreement among many stakeholders.
Maintenance must be shifted from periods of high wind. CLP, in the next few months, aims to implement changes in SCADA at one of its wind farms to adopt energy-based availability. The first point of contact while considering upgrades on a WTG will be the OEM, as in many cases it involves software upgrades at the controller level besides hardware changes. CLP is implementing an annual energy production (AEP) improvement project called Power Boost at its wind farms; it is expected to provide 2 per cent improvement in annual energy production. The company is also implementing an extra power programme at another wind farm, and vortex generator strips retrofit at two of its wind farms, which are expected to give a 1.8-1.9 per cent improvement in the power generated annually. In addition to these initiatives, the company is conducting specific studies to identify the extent of static yaw misalignment and relative blade-pitch misalignment. Other proposed studies include electrical signature analysis where advanced sensors are retrofitted and the high-frequency data generated is analysed and combined with ML to detect torque anomalies and yaw misalignments. These modifications/upgrades and studies are especially important after the machines cross 10 years of their lifespan. Life extension is also something that is on the cards. Different companies have different strategies to deal with this. One of the important questions to be answered is at what stage the company starts implementing actions for this process. In India, the life of a machine is only 20 years and a PPA is signed for 25 years. Not much thought is given to what is required to be done to keep them running for the entire period. Ideally, the planning should begin by year 15 (some software can help predict the expected life). Going forward, CLP aims to alter O&M contracts after the first 10 years so as to meet requirements under a “change” scenario.
O&M can be measured through asset reliability and quality. At the same time, performance should not be allowed to deteriorate in terms of the annual energy production that has been forecast. At the end of 10 years, there is usually a loss of 1-1.5 per cent in the annual energy production which might not have been taken into consideration at the pre-construction stage. There must be plans to compensate for this loss through retrofitting VG strips or some other measures so that the energy production from the fleet is not lost. Among other measures, one way of improving reliability is to prevent fires on turbines; this can be done by retrofitting fire suppression systems since firefighting systems are not supplied as a standard practice and older machines are susceptible to fire. There must also be advanced intruder detection systems for machines installed in remote areas.