wind turbine construction materials
Transformers are wind-Step Up the weak link of the wind energy supply chain
In the race for cash Wind Energy, developers are often the first trading costs low for the higher total costs of ownership to be supported later by the owners and operators of wind farm
Converting wind energy to energy Power is the fastest growing segment of the U.S. energy sector. Today, wind energy represents less than 5% of electricity production in the United States and aims to reach 20% in the foreseeable future. To do this, new sites must be developed Despite a downturn in the economy running.
Fort dollars available federal stimulus, we are witnessing a virtual day Modern Land Rush '. In the words of an industry leader, "if there is a site that has a viable wind profile, access network connections, and access for delivery of materials, and we do not develop it, someone else will. "
The long head nail to install wind turbines increasingly exceeded the normal development curve for learning, where new technologies mature through a process of trial and error, resulting in the definition of equipment suitable for the job hand.
The additional economic pressure on the market today made an already competitive market even more demanding. It has, in the opinion of many industry insiders, helped in the purchasing decisions of equipment based largely on the lowest cost initial solutions and not solutions that provide the best choice in terms of total cost of ownership, network stability, less time and revenue losses From high maintenance issues. This is nowhere more apparent than in the case of wind turbines (WTG) processors.
Historically Wind turbines that function of the transformer has been treated by conventional off the shelf distribution transformers, but the relatively high number of recent failures suggests strongly that the WTG transformer drawings must be made much more robust. The practice of using traditional "off the shelf" distribution transformers as a low cost solution is madness. In some cases, the site operators are maintaining a quantity of spare transformers to fight against the frequent breakdowns caused by transformers standard distribution used where they are not suitable.
The role of wind Turbine Generator (WTG) processor in this process is essential and as such, its design must be carefully considered and analyzed and evaluated.
Transformer Loading:
Wind turbine output voltages ranging from 480 volts to 690 volts. The output of the turbine is converted by the transformer WTG to a collector voltage of 13,800 to 46,000 volts. The turbines are heavily dependent on local climatic conditions, and this may result in average annual load factors only 35%. Loading relatively small wind turbine transformer has a positive effect on the life of isolation, but introduces two unique and functionally important problems.
The first problem is a light load or idling losses become more important basis so economic losses coil or coils become less important. Typically used the formula for determining the costs apply not in this scenario. NEMA TP1 DOE and efficiency are not modeled for the scenario of operation where the average load is about 30-35% and therefore should be carefully applied when calculating the total cost of ownership for transformers of wind turbines.
The second problem is that the transformer wind turbine is subjected to frequent thermal cycles for different loads of the turbine. This causes repeated thermal stress on the winding, clamping structure, and joints. Repeated thermal cycles causes of nitrogen gas to be absorbed into the hot oil, then released as the oil cools, forming bubbles within the oil can migrate insulation and windings to create hot spots and partial discharges can damage the insulation. The thermal cycle may also cause accelerated aging internal and external electrical connections.
Harmonics and non-sinusoidal loads:
Transformers WTG are put in a solid state controls to limit inrush currents. Although potentially help in the development initial tension, these electronic controls contribute damaging harmonic voltages which, when combined with non-sinusoidal waveforms by wind, can not be ignored from the point of view of heating. When the system of a chopper rectifier / is used, the transformer WTG must be designed for harmonics similar to rectifier transformers, taking into account the additional load and provide electrostatic shields to prevent the transfer of harmonics between the primary and secondary windings.
Transformer sizing and voltage variation:
WTG transformers are designed so that the voltage is adapted to the output voltage of the wind exactly. It is not designed "over-voltage capacity to overcome the voltage fluctuations that are a common problem with wind turbines. At the same time, the generator output current is monitored on a millisecond and operational limits allow a maximum of 5% over current during 10 seconds before it is removed from the system. Therefore, the WTG transformer is designed to match the output without overloading the generator sizing and design of wind turbine transformer must be unique robust to function without it.
Obligation to withstand fault currents:
In general, conventional distribution transformers, power transformers, and other types of transformers step-up "abandonment" when subjected to a fault. Once the fault has cleared the distribution transformer is brought back online. Wind turbine generators, on the other hand, to maintain the stability of the network are not allowed to disconnect from the system due to system disturbances, except in certain guidelines developed for power production. The length of the generator is necessary to remain online may vary. Meanwhile, the generator will continue to deliver a voltage transformer to the abnormally low WTG. Therefore, defects in the transformer may be necessary as low as 15% of nominal voltage of a few cycles, then ramp back up volts full seconds after fault clearing. The WTG transformer must be designed with only enough of the "robustness" to withstand full short circuit current during the first few cycles when the maximum mechanical forces exerted on the windings of transformers of wind turbines.
Conclusions
The role of transformers of wind turbines in the system today Wind generation is unique, the design must also be unique and robust. Do not trade long-term reliability and reduce total cost property for a low initial cost.
Pacific Crest Transformers is a leader in the design and construction of target = "_blank"> distribution transformer. Learn more about target = "_blank> Transformers," target = "_blank"> WGT Transformers and information relating to the PCT.
About the Author
Mike Dickinson began his carrier in transformer industry in 1972 at Pacific Crest Transformers. Currently Mike is in charge of Business Development at PCT .
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