Around 90 km away from Madurai, in a little known town called Kamuthi, Tamil Nadu, rises a structure that has the potential to be monumental in its own way.
As the bird flies, the sight of 2.5 million solar modules spread over 2,500 acres of land depicts an ambitious display of the finest solar technology in a remote, agrarian and a non-industrial town like Kamuthi, Tamil Nadu. Leaving aside engineering, procurement, project management and site construction a challenge, building a 648 MW structure in a single location was indeed an unimaginable task to accomplish.
While racing towards a tight deadline, even when Mother Nature decided to throw in a few surprises, the 8,500 pairs of hands were in no mood to let anything eclipse their progress. These personnel worked hard day and night on the herculean task of installing upto 11 MW or 40,000 solar modules every day to set up the plant in the stipulated time.
In 2016, the Adani Group commissioned the world's largest solar plant in a single location, a strong contribution to India's goal of 100 GW of solar power by 2020. Built in Kamuthi, 90 km from Madurai, the Adani solar project surpasses the California-based Topaz Solar farm which has a capacity of 550 MW and completed in about three years. The massive 648 MW Adani solar project, contributes to the country's renewable energy vision, with the overall aim of diversifying the energy mix to meet growing demand, while minimising environmental impact. Strategically, for such mega size solar structure, it demands a huge patch of land, good solar radiation and the proximity with port for logistic purposes. Luck prevails, all these were found at one single location-Kamuthi.
The plant, spread over 2,500 acres, enables clean power supply for around 150,000 households, based on an average national per capita consumption, and accounts for about 10 per cent of India's solar power output. The plant is part of the state government's ambitious yet highly achievable target of generating 3,000 MW as per its new solar energy policy unveiled in 2012. The company sourced equipment and machinery from various parts of the world to set up the entire 648 MW within a record time of eight months.
The massive plant comprises of 3.80 lakh foundations, 25 lakh solar modules, 576 nos of inverters, and 154 nos of transformers. The entire plant was completed and was ready to generate the promised 648 MW of clean and green energy by March 2016, however, due to non-availability of grid connectivity, only 360 MW could be commissioned.
The entire 648 MW is now connected through the Kamuthi 400 kV sub-station of TANTRANSCO making the plant the world's largest solar power plant at a single location.
During the construction period Adani officials had to supervise the simple yet a critical process.
The quality management team had to ensure piles erected pass a pull out test. A pressure of 1,200 kg/sq cm is applied to the pile. And if it stays put, it passes the pull out test, an indication that the pile can survive high wind speed and any other force of nature. Eventually, 25 lakh solar modules were to rest easy on galvanised steel. Around 30,000 MT of galavanised steel were used - one can construct more than four Eiffel Towers with that much steel.
The panels alone occupy an area of 1,270 acres of land, equivalent to 470 football fields. The module mounting structures (MMS) have been grouped into tables with specific capacity i.e. one table can generate almost 50 kW of electricity. The amount of metal that was used to make these piles, tables and towers is mind boggling.
The entire 648 MW of plant is made up of clusters of modules of 4-5 MW each. Inverters are linked to these solar modules. Here, around 144 pre-engineered buildings are made just to house the 576 inverters required for this plant. All this would require a lot of cabling. Wires of different shapes and thickness are connecting the dots in this massive solar puzzle. Almost 7,700 km long! These cables can run all the way from New Delhi to Perth in Australia.
Meanwhile, if it is not a cloudy or rainy day, electricity generation can take a hit if modules are dusty. Luckily, solar power plants are relatively easy to maintain. An average photovoltaic cell may last 25 years if it is regularly cleaned. In Kamuthi, what would otherwise a manual and water intensive job is now being mechanized with state-of-the-art robotic technology from Israel. Here, waterless clean technology is a game changer semi-urban dry region like Kamuthi where it is a scare resource. The robotic solar power cleaning system uses soft micro-fibre on wheels that push dust off the modules. The robotic systems can be remotely monitored, managed and controlled.
Meanwhile, ABB's solutions were roped in for end-to-end power and automation solutions to the solar power plant.
ABB's project scope included the design, supply, installation and commissioning related to the solar plant electrification and automation systems. This included two 230 kV and three 110 kV outdoor switchyards to connect to the local transmission grid. Power equipment from ABB included supply of control relay panels, circuit breakers, current transformers, capacitor voltage transformers, protection systems, fibre optic telecommunication equipment, SCADA system, inverters and power transformers.
The project was completed in a record time of eight months. It involved a high level of sophistication in project management and coordination, right from the engineering stage through to the execution on site. An optimised design was created with a common layout for all the sub-stations, for ease of execution. Multiple teams were deputed to work simultaneously, and as work continued round the clock, a high degree of safety measures was implemented. The sub-stations were completed in March 2016. The plant is a good example of how the Internet of Things (IoT) is executed by ABB. All equipment across the plant is integrated and controlled with ABB's Symphony Plus SCADA system. Symphony Plus, ABB's unified automation platform, forms the digital backbone of the massive solar power plant.
Equipment across the plant, including inverters, switchyard, switchgears and weather stations, are monitored and controlled using sophisticated software from this common automation system.
Due to its large scale, any fluctuation in the plant output power will affect the grid operations. The project works on a first-of-its-kind control philosophy to maintain the power output of the plant at the grid demand.
There are five automation systems ù one for each substation and a central control room. This automation system offers a single view of the plant, enabling plant performance monitoring, enhanced operational efficiency and ensuring grid compliance. The IEC 61850-based automation system facilitates local and remote monitoring and control of the plant and substation assets, and paves the way for adapting IoT-based solutions in the near future.
Symphony with solar
Symphony Plus for Solar employs a SCADA system for monitoring all key plant components, from PV panels (with and without tracking systems) to the inverters, transformers and switchgear, grid connection and meteorological stations. It supports a broad range of communication protocols like Modbus TCP, OPC, IEC 6087-5-104, enabling it to connect and exchange data with all plant components. With a real-time database and a historian, relevant plant data can be acquired and either stored on site, or forwarded to a remote management center.
One of the key differentiators of Symphony Plus for Solar is the capability to monitor and control plant and substation equipment using the IEC 61850 protocol. This enables ABB's solution to integrate generation and electrical components into single information and control system. With the built in interlocking schemes, secure and easy operation of the protection equipment in the plant or at the grid connection is achieved, from site or remote.
Remote management of PV plants
For this project ABB has provided SCADA solutions that enable remote management of the plants. The solution integrates, monitors and manages all generation assets into a single system, independent of the plant technology or provider. The flexible and versatile SCADA system built on a hierarchical architecture allows for effective management of only a few or hundreds of plants. The remote management system is based on the same Symphony Plus technology, therefore the HMI, the power management module and the forecasting application can easily be deployed also at enterprise level.
The power production of the entire fleet can be controlled in real time and scheduled for intra-day planning. This facilitates the virtual power plant concept and allows renewables to participate in energy markets.
The Adani Group is in a phase of revolutionizing the renewable energy ecosystem of India by building solar power plants, solar parks and manufacturing facilities with seamless integration. Setting up of the 648 MW solar power plant in Tamil Nadu is a step in this direction.
- Rahul Kamat