Solar Journey

Adani’s Tamil Nadu plant sets an example

A Renewable Watch team recently visited Adani Power’s 648 MW solar power plant in Tamil Nadu, accompanied by Jose Joseph, senior vice-president, transmission and distribution infrastructure and grid integration solutions, power grids, ABB. The following are the highlights of the plant visit.

The two-hour-long drive from Madurai to Kamuthi was fairly uneventful, save for an elephant nearly hitting our car. The village road ended abruptly and up ahead, all we could see was endless miles of solar modules that extended to as far as the eye could see.

Adani’s modern, world-class 648 MW solar power plant stands in stark contrast to the dilapidated villages of Sengapadai, Pudukottai and O’Karisalkulamin taluka, Kamuthi. Spread across 2,500 acres, the plant has been developed by the Adani Group with balance of system (BoS) technology provided almost entirely by ABB India Limited (ABB). About 2.5 million solar modules have been procured from eight different suppliers across the globe, while the civil works, which included the construction of about 380,000 foundations for the installation of solar modules, have been carried out by different agencies engaged by the Adani Group. The plant incurred a total cost of about Rs 45 billion.

Located in the south-western region of Tamil Nadu, the plant was fully commissioned on September 21, 2016. It has five separate units, each with a dedicated substation – three units with a capacity of 72 MW each and two of 216 MW each. The plant was built in a record time of eight months, with about 8,500 personnel working day and night with floodlights illuminating the area. The extreme heat and humidity conditions pose a major challenge in operating the plant. The plant achieved 10 million safe working man-hours and holds the distinction of being the largest accident-free project.

Technology

ABB is one of the primary technology partners for the plant with complete automation of the solar plant, which extends to about 18 square km. The developers have used ABB’s Symphony Plus solution for the monitoring and control of the plant. This enables the plant to be controlled at various levels, from the inverter to the substation. In addition, the solution controls the associated dimensions of panel position as well as power management. Also, ABB has provided half of the inverters required at the plant through 288 inverters. ABB has also implemented the supervisory control and data acquisition (SCADA) solution, part of the Symphony Plus package, to enable remote operations and management of the system, especially required for such a large-scale solar power plant. The vastness of data management and operations required can be gauged from the data pouring in on multiple screens inside the SCADA room. The SCADA system connects the panels, inverters, transformers, switchgear, substations and the grid, along with the meteorological stations, to provide a single-window holistic view of the performance of the entire plant.

Pointing to the red blinking lights on the screen, the person manning the SCADA system explained the role of the unique integrated alarm system that ensures quick and speedy identification of relevant plant issues. This helps ensure timely diagnostics and optimum power generation at all times. An exact replica of the SCADA output is provided to the client at the head office in Ahmedabad for easier multi-level decision-making.

Operations and maintenance, particularly of such a huge plant, is challenging. However, with relevant data displayed on the screens in real time, operators have access to the key parameters at all times. Generation data from each inverter, which connects a number of modules, is displayed on the screens. The fluctuating numbers show real-time generation as per the ambient conditions on the ground.

To achieve multi-level operational efficiency, individual SCADA rooms and supervisors are stationed at each unit of the plant. This helps the operations team to be aware of a non-performing panel, the reasons for low generation and the maintenance required for the panels. For instance, if a panel is recording less than optimum generation as opposed to others, a probable cause could be dust that can be washed away immediately.

A consolidated view of the system enables improved plant performance monitoring, which enhances operational efficiency and grid compliance. The IEC 61850-based automation system provides greater multi-faceted control of the plant and equipment, while also facilitating better integration of advanced technologies such as internet of things in the near future.

The design, supply and installation of the plant provided by ABB also include outdoor switchyards that connect the plant to the local transmission network. A total of five switchyards have been used, two rated at 230 kV each and the other three with a rating of 110 kV each. Other equipment provided by the company includes control relay panels, circuit breakers, current transformers, capacitor voltage transformers, protection systems, fibre optic telecommunication equipment and power transformers.

The 648 MW solar plant feeds a large amount of power into the grid, significantly affecting operations at the transmission network level. However, the technology provided by ABB works on the principle of maintaining output from the plant as per the requirements at the grid, akin to coal-based power generation. Also, the system constantly interacts with changes in weather conditions to adjust the inverter set-points and maintain the power output.

Challenges

Executing such a large-scale project in extreme weather conditions has its own set of challenges. Joseph explained that one of the most crucial challenges experienced by ABB was the timeline. The plant was to be installed and commissioned within a short duration. And while heat and humidity posed a constant challenge for the 8,500 workers, floods inundated the area with knee-high water, stopping all work for a period of about two months. Also, to ensure timely completion of the plant, day-like work conditions had to be created at night for the personnel, for which floodlights were installed at the site.

Conclusion

The 648 MW Adani solar power plant generates smart electricity as it has the ability to adapt to its environment and ambient conditions at the grid. It also marks the achievement of various milestones for developers and technology providers with regard to the execution timeline and scale of operations and maintenance.

The plant has given the Indian solar energy segment a number of best practices and project management and execution goals to follow, as the country aims to deliver 100 GW of solar power by 2022. This includes a number of solar parks and ultra mega solar power plants that would require greater technology, resilience and efficiency as displayed in this solar power project.

The challenging conditions in which the plant was built and is being operated can only be experienced first-hand, as I did. The world’s largest single-location solar power plant has set high standards in technology, project execution and operations, paving the way for future large-capacity solar power projects.

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