The Huangang wind farm is one of seven projects developed by Jiangsu Longyuan Wind Power company, a subsidiary of Beijing-headquartered Longyuan Power Group. It is one of the earliest large-scale wind farms developed in China and has received many visitors, including high-profile government officials. The most prominent of them is perhaps former Chinese president Jiang Zeming, who toured the wind site in May 2008.
The site includes a building with two transformer substations and working and accommodation space for the team of workers, charged with operating and maintaining the 105 GE 1.5MW wind turbines.
Round-the-clock monitoring of the turbines is carried out inside the main control room, where seven computers and a screen on the wall display real-time performance of turbines set in two rows. The wind farm is located on a narrow strip of land about 60 kilometres long and just a few hundred metres from the sea.
Most of the operations are controlled remotely by an all-weather round-the-clock system, developed by the Longyuan Group. After much negotiation, GE agreed to share its machine codes, allowing project director Yang Fan and his team to remotely monitor and control the turbines. Field work is carried out for regular maintenance checks or when there is a fault.
The remote system shows live conditions of the entire wind farm and each individual turbine: wind speed, wind-power predictions and energy capture, as well as the state of transformer substations. There are plans to upgrade the software to provide data analysis, to be able to give technical advice on specific turbine issues by involving a taskforce of senior technicians, and to create a training centre to further the competence of the workers.
The headquarters of Jiangsu Longyuan in Nantong City has a main control room (pictured) that runs a similar monitoring system looking after the operations and maintenance (O&M) of all seven wind farms under its care. This 24/7 system alerts the individual power stations should they spot any problems. The control centre of Jiangsu Longyuan serves as a double check and, especially at night, relieves the burden of night shift workers on project sites, allowing them to get some sleep.
Until recently, Yang Fan maintained the site with a team of 13 technicians, with additional help from Longyuan Power Group's specialised maintenance firm based in Jiangsu. But the group recently resolved to scrap its maintenance firm, and Huangang has accepted eight additional technicians as permanent staff.
The 21-strong crew work will work on a seven days on, seven days off cycle, with three shifts in a 24-hour day. Every technical worker is assigned a number of turbines for at least a year and is responsible for the well-being of his machines. He also takes care of other turbines when necessary. Appraisals are conducted the end of the year. "The practice enhances the sense of responsibility and helps lift working standards," Yang Fan says.
A typical day begins with a morning meeting, where the group leaders and maintenance-company worker report on work from the previous day, and Yang comments and then briefs them on the tasks for the day.
A group of three workers perform weekly maintenance on the lower part of a turbine - mainly the computer, convertor and cooling system, and twice a month, two workers check the nacelle. Each turbine is cleaned and has oil replenished every six months. On an annual basis, 10% of the turbines are selected to check the state of the oil and bearings, and are tested on performance such as yawing and abrupt stop and corrected on centering.
Huangang welcomes suppliers of major parts such as electric motor, gearbox, blade and bearing to come and check their products. The companies are usually happy to do so, because it generates business if they spot any problems.
Huangang has turned a profit over the past few years - being a state-level project in a good local economy it does not suffer from the grid or curtailment problems that plague many wind developers, including fellow Longyuan companies. The project is in a category IV wind region, with relatively low wind speeds. Compared with other coastal provinces in the south, Jiangsu is less prone to devastating typhoons, which caused a grid outage of nine turbines in 2013. Accidents are more frequent at the two main substations, each boosting electric pressure from 35kv to 110kv. And minor instances such as tripping are difficult to prevent, Yang Fan says.
So far, the GE turbines have performed well. But the profit margin narrowed in 2014 because the wind was slower, and conditions last year were similar. Profits will inevitably fall as machines age, capturing less energy, and maintenance costs rise with the replacement of old parts, says Yang Xifeng, director of the planning and development department at Jiangsu Longyuan.
Early in 2015, Huangang adopted GE PowerUp software for capacity enhancement. The program claims to boost the capacity of a 1.5MW turbine to 1.68MW. Revenues from related additional output will be shared with GE.
To further enhance output, Huangang has considered lengthening the LM 37.3-metre rotor blades, but the cost would be high and it would only be plausible if the replaced blades are sold on at a good price for reuse. There are currently no plans to replace the present GE machines with larger turbines, according to Yang Fan.
The turbines have a 15-year lifespan, but Longyuan expects the machines to run 20 or 25 years. Component and parts supply may prove a problem later, and already Huangang has had to use some non-GE approved parts to fix failed turbines, which means rewriting part of the machine codes and extra costs.
A small stock of spare parts is kept on site, and when Huangang needs a part that is not available in the warehouse, it contacts GE or other Longyuan wind companies. Longyuan Power shares its inventory among the group, and, being the largest wind developer in China, it has other projects with GE turbines.
The warranty period for the GE turbines in the first two phases was three years, but Jiangsu Longyuan chose a one-year warranty period for the third phase turbines. Knowing the turbines, they felt confident that they could handle the maintenance work, and so took advantage of GE's flexible post-sale package. As the warranty periods finished, Yang Fan's team took on the operation and maintenance role. They now have responsibility to operate and maintain all the turbines, including problem solving, fixing and change of parts.
Life on a remote wind farm is unusual. The Huangang station is situated in a rural coastal area. The nearest urban community, in Rudong County, is about 20km away. The average age of Yang Fan's technicians is 26. Eight of them are unmarried. And most of the married men have families living in Nantong City, which is about 100km away. For the unmarried young men, dating opportunities are limited and life outside work can be monotonous. The company compound has a basketball court and there is a reading room, a gym and a snooker table inside the building.
Yang Fan himself had worked as a technician at Jiangsu Longyuan after graduating from university in 2007 with a degree in mechanical and electrical integration, before joining Huangang in December 2012 as its fourth director. His wife works at Jiangsu Longyuan headquarter in Nantong. They have a two-year-old daughter. To the little girl, daddy just disappears mysteriously most days.
As director, Yang Fan (left in picture) says he might not be able to work to the double-seven-day rhythm. He has lots of obligations to fulfil during the work day: coordinating issues involving local communities, receiving visitors, checking on security operations, to name just a few.
The day shift ends around 7pm after the team reviews the work done during the day in a final 30-minute meeting.
AT A GLANCE — HUANGANG WIND FARM
- Coastal site on a narrow stretch of plain terrain, with local average annual wind speeds of 6.9 metres per second and around 2,200 annual hours of wind available
- Project capacity 157.5MW, made up of GE 1.5MW turbines
- First phase of 39 turbines was commissioned in 2007 as a state-franchised project. The second and third phases added another 66 turbines by 2011
- Project generated 250 gigawatt hours of electricity in 2014, sold to the local operator of the State Grid Corporation, via a grid feed-in contract signed every five years. The 20-year FIT rates per kilowatt hour are CNY 0.519 ($0.153) for the first phase, and CNY 0.61 ($0.093) for the rest. As the local economy is fairly strong, power demand is high and the wind farm does not suffer from curtailment.