L&T OMAN’S LARGEST GRID STATION, DELIVERED WELL AHEAD OF TIME.
NAHADAH 400/132 kV, 2×500 MVA TRANSFORMERS GRID STATION
The Nahadah 400/132 kV, 2×500 MVA Transformers Grid Station, the largest executed by L&T Oman, has set new standards for swift execution. Little wonder that it bagged the Timely Delivery Award 2022! Located near the Petroleum Development Oman (PDO) Booster Station in the Ad Dakhiliyah Governorate, Oman, the Grid Station will, on one hand, meet the growing loads in the area and, on the other, create a unified National Electricity Grid to connect Oman’s north and south grids. It will also cater to PDO’s electrical load by interconnecting the PDO network with that of the Oman Electricity Transmission Company (OETC).
The scope for the Nahadah Project involved the construction of a Grid Station consisting of 14 bays of 400 kV GIS associated with control and relay panels. The incoming 4 OHL feeders tap from the existing 400 kV Ibri–Izki OHL, and the outgoing transformer feeders (400/132 kV, 500 MVA power transformer) feed the PDO loads through 10 bays of 132 kV GIS. Another two 400 kV OHL feeders connect to other regions.
“This project is the first node in the Rabt Phase-I Project (Oman Vision 2040), and the Grid Station serves as the heart of the network expansion from Ad Dhakhiliyah to Dhofar regions to ensure maximum power transmission efficiency,” explains Ravi Raikar, Project Manager, who is all smiles for winning the Timely Delivery Award. “The original contractual completion date was 29th April 2022, while a delay in events and additional scope shifted the date to 23rd September 2022. However,” he adds, raising a finger emphatically, “our actual completion date was even earlier than
the original one.”
“The original contractual completion date was 29th April 2022, while a delay in events and additional scope shifted the date to 23rd September 2022. However, our actual completion date was even earlier than the original one.”
Ravi Raikar
Project Manager
“Right from Day 1 of the project, our goal was set to complete the project 3 months ahead of schedule, and this timely completion award was targeted on Day 1 itself,” confirms Construction Manager, Natti Venkat Raman. “This was cascaded to all the team members, and they were boosted through various meetings and interactions to have a clear mindset to complete the project ahead of schedule.”
“Eight 132 kV GIS bays were installed and tested in a record time of 21 days, while the fourteen 400 kV GIS bays were completed in less than 6 months, which was crucial for the early completion of the project.”
Natti Venkat Raman
Construction Manager
Delays follow one after the other
Awarded in March 2020 during the peak of the pandemic, and with the inter-governorate lockdown and international travel ban imposed by the Oman Governorate, mobilization, procurement, and authority approvals proved to be uphill tasks. “With the uncertainty in the market, vendors were withdrawing their tender offers and increasing prices, which delayed the procurement process,” recalls Planning Manager, Mohamed Itries. “Procuring major equipment such as the 400 kV & 132 kV GIS and 500 MVA transformers was possible only in June, which further delayed mobilization, manufacturing, and engineering schedules.”
OETC’s normal practice warrants a mobilization audit before execution. Unfortunately, a storm just a week before the planned audit with the client blew away the entire set-up, delaying the mobilizing audit, and thereby construction,
by one month.
Adding to their timeline woes was the Suez Canal blockade by the Ever Given container ship, which delayed the arrival of the 400 kV GIS. “Although we had successfully overcome manufacturing delays and ensured the timely delivery of most equipment, due to the Suez Canal issue, our 400 kV GIS shipment took nearly 66 days to arrive at the site, as opposed to the originally planned 40 days,” Mohamed Itries moans.
“Although we had successfully overcome manufacturing delays and ensured the timely delivery of most equipment, due to the Suez Canal issue, our 400 kV GIS shipment took nearly 66 days to arrive at the site, as opposed to the originally planned 40 days.”
Mohamed Itries
Planning Manager
During the second wave of the pandemic, as fatalities soared, the government imposed strict rules in May 2021, including one on international travel. “The team was prepared to install some major equipment,” he points out, “but the equipment supervisors were unable to travel. The ban was lifted only in September 2021, and the equipment erection commenced only 60 days after the originally planned date.”
Adapting to changing scapes
Based on the soil investigation report, the initial design for the plot required a retaining wall with a total fill height of 13 m. To reduce the cost, and after considering various alternatives, it was finally proposed to reduce the size of the plot, which was well received by the client as it saved both capital investment and rent. “To tackle the uplift pressure of soil, void former with sacrificing material was implemented for the first time in an OETC Grid Station project,” adds Siva Kumar, Civil Manager.
“To tackle the uplift pressure of soil, void former with sacrificing material was implemented for the first time in an OETC Grid Station project.”
Siva Kumar
Civil Manager
Further changes to the scope were forthcoming just as most of the engineering work had been completed and piling work was underway. “We were eight months into the project when the client requested changes to the control philosophy, ownership, and segregation,” frowns Gopalkrishna Kamath, Senior Engineering Manager. “We proposed an alternate solution to address these changes, which, however, delayed the SCMS design and delivery, and the entire process had to be started all over again.”
“We proposed an alternate solution to address these changes, which, however, delayed the SCMS design and delivery, and the entire process had to be started all over again.”
Gopalkrishna Kamath
Senior Engineering Manager
The external road profile was redesigned to avoid the PDO gas pipeline crossing. “To achieve ground clearance for the 132 kV OHL PDO line, we redesigned the road gradient, which avoided the diversion of the OHL and reduced cost,” explains Siva Kumar.
The existing optical ground wire (OPGW) was rerouted during the initial stage, which reduced the shutdown time. With summer approaching, a 7-day shutdown was proposed for each circuit instead of the original plan of 30 days. “Based on their previous experiences with other contractors, the LDC department of OETC were concerned that the work would not be completed within 7 days,” reveals N V Raman. ”The CEO, COO, and CTO of OETC were explained about the shutdown plan. They were convinced by our proposal and approved the 7-day shutdown, which we completed for each circuit as committed,” he adds with a proud smile.
Delivering promises, and then some
The project recovered from the initial delays through effective catch-up plans executed by a committed team. “By expediting design approvals/MFC, we received the equipment two months ahead,” begins N V Raman as he lists out the team’s achievements in meeting schedules. “495 piling works were completed one month in advance. Eight 132 kV GIS bays were installed and tested in a record time of 21 days, while the fourteen 400 kV GIS bays were completed in less than 6 months, which was crucial for the early completion of the project.”
In addition, the team also overcame several cost challenges during the execution:
- The original bid included a single-break GIS system, but the client requested a double-break system without any additional cost implications.
- The price of the transformer increased by 30% during the pandemic. An alternative vendor with a better offer was proposed, though a 12% impact on the cost had to be absorbed.
- The contract value was also affected by 3.5% due to currency fluctuations.
“Despite all these challenges, we still maintained the targeted gross margin and tried every bit to improve it as much as possible,” reveals R B Satish, Accounts Manager.
“Despite all these challenges, we still maintained the targeted gross margin and tried every bit to improve it as much as possible.”
R B Satish
Accounts Manager
With due consideration, the client had granted a time extension of 147 days from the original contractual completion date. The Grid Station was, however, energized prior to even the original date – a testament to the Nahadah Project team’s competency and persistence!
“We had the Quality Award in our sights, having won the Quality Trophy at the PT&D IC level. This Timely Delivery Award at the organization level is clear evidence of our team’s sheer grit and determination, and an inspiration to all of us to continue our journey forward in high spirits!” remarked Ravi when receiving the award from SNS, gushing
with pride.