“...we chose DEIF because they seemed most committed to support us.” says General Manager of Dongfang
In 2010, the high runner in the turbine portfolio of Chinese wind turbine manufacturers Dongfang Steam Turbines (DFst) was a license manufactured original Repower 1 .5MW doubly fed design. The turbine was manufactured by the thousands and for various reasons DFst wished another maker of the main control system for the turbine.
DEIF Wind power Technology designed a complete electrical design for the machine – turnkey-ready control switchboards to replace the original design. The control strategy was developed using advanced modeling and simulation. The modeling was based on the specific aerodynamics of the blades of the MD70-turbine and therefore allowed for development of an ideal pitch strategy.
Two major goals for the pitch strategy were pursued:
- Fast but smooth regulation at rated maximum power production. Keeping the turbine at maximum rated power production applying a minimum of mechanical force was a major concern in order to minimise the fatigue loads on the entire construction.
- Maximisation of yield at any operation below maximum power production. Full utilisation of the wind power potential is a crucial factor still with due considerations regarding the overall mechanical stress of the entire construction.
The control solution prototype was manufactured and shipped off to DFst’s manufacturing site in Chengdu where the Factory Acceptance Test was carried out in a close cooperation between DFst engineers and DEiF engineers who were on-site from HQ in Denmark and from DEIF China in Shanghai.
The general Manager of DFst says: "We could have chosen several different manufacturers of our new control solutions – but we chose DEIF because they seemed most committed to support us. In that respect, it was also important to us that DEIF has a local R&D and service organisation in China. The commitment of DEIF to support us became crucial when we wished to take over the production of the control switchboards. DEIF sent all relevant staff on-site to help us implement the design in our production and everything went smoother than we could have hoped for.
We are now far beyond 1,000 control solutions delivered from DEIF’, the GM of DFst says. ‘That is why we can say without hesitation that DEIF is as a very reliable and committed supplier’. No matter where the solutions have been deployed, they have provided reliable performance.
With other equipment, we have had to deal with issues regarding temperature and mechanical robustness – that is not the case with the controllers from DEIF – they work when we receive them – and they keep on working", the GM concludes with a smile.
Maintenance Minimising control Strategy
Aspiring to achieve a maximised yield at any given wind condition implies a relatively regulation-intense control of the blades of the turbine. Apart from yield-maximisation, this control strategy implies an advantage in terms of early fault detection as each blade is moved very frequently, thus providing a continuous monitoring of the function of the pitch system components (drives, bearings, etc.).
In other terms, error detection carried out by a control system relying on continuous regulation is more likely to happen during low-wind conditions compared to systems relying on a less frequent regulation.
Increased Power Production
The first site with DFEIF 1 .5MW turbines equipped with DEIF Wind power Technology control equipment was Mao Ming counting 33 turbines. To measure the efficiency of the applied control solution, the individual production of each turbine was monitored and compared with the power curve of the original design. The resulting calculated difference appears from the below diagram for each turbine. Except for three poorly adjusted turbines, the diagram shows a significantly increased production compared to the original design.
The measurements and calculations indicate that a DEIF-controlled turbine will produce approx. 5% more energy than the original design, equaling 6 million kWh annually for the Mao Ming wind park.