In the rush to collect the wind energy developers are behind too low commercial cost of higher total cost of ownership later by the wind farm owners and operators.
Production of wind energy into electrical energy is the fastest growing segment of the energy sector of the United States. Today is the energy of wind is less than 5% of U.S. electricity generation and is expected to reach up to 20% in the near future. For this to happen, new sites are being developed, despite a lowTurning to the economy.
Supported by decree of the U.S. dollar federal stimulus, we see a virtual "land rush" modern. In the words of an industry leader, "if it is a site that has a viable wind profile, access to network connections and access for delivery of materials, and we develop is someone else."
This head-long rush of wind turbines ever installed has the usual learning curve of development, where new technologies mature through a process of trial exceededand errors, such as the definition of appropriate equipment for the job at hand.
The additional economic pressure on the market today is already competitive market even more difficult. This has, according to many experts, led in large part in the decision to purchase the equipment at lower cost solutions and not solutions, the best choice in terms of total cost of ownership, network stability, provides time downtime and lost revenue base by highMaintenance problems. Nowhere is this more evident than in the case of wind turbines (WTG) processors.
WTG transformer function historically has been treated by the conventional "off the shelf" distribution transformers, but the relatively high number of recent failures strongly suggest that it would designs WTG transformer must be made more robust. The practice of using conventional "off the shelf" distribution transformers as a cost-effective solution is madness.In some cases, site operators to maintain a quantity of spare parts of transformers for the frequent interruptions that are used by the standard distribution transformers which are not suitable for combat.
The role of the wind turbine generator (WTG) transformer in this process is of paramount importance, and as such should be the design, carefully and thoughtfully analyzed and evaluated.
Transformer loading:
Wind turbine output voltages ranging from 480 volts to 690 volts. The turbine performanceWTG transformed by the transformer, a collector voltage of 13,800 to 46,000 volts. The turbines are highly dependent on local climatic conditions, and this can result in a lower average annual use of 35%. The relatively light load of WTG transformer has a positive influence on the life of isolation, but provides two unique and functionally significant problems.
The first problem is when a light load or idle, core losses become a major economic factors, whileWinding losses are becoming less important. Usually used in price evaluation formula does not apply to this scenario. NEMA TP1 DOE and efficiencies are not responsible for the operational scenario is modeled in which the average speed of about 30-35% and therefore should be used cautiously in the calculation of the total cost of ownership for WTG transformers.
The second problem is that the WTG transformer is subject to frequent changes in temperature according to the differentTurbine loads. This leads to repeated thermal stress on the structure of tightening spiral, seals and gaskets. Repeated fluctuations in temperature causes nitrogen gas into the hot oil to be absorbed and then released as the oil cools, forming bubbles in the oil can migrate in isolation and winding hot spots, and partial discharges that can damage the insulation . The change in temperature can also cause accelerated aging of the electrical connections inside and outside.
Harmonicsand non-sinusoidal loads:
WTG transformers were switched to solid state controls to limit inrush currents. Although potentially help the initial excitement to wear the same electronic control damaging harmonic voltages, which, coupled with the non-sinusoidal waveforms of the turbines, not ignored from the point of view can be heated. When a rectifier / chopper system is used, the WTG transformer for harmonic rectifiers and transformers are designed similarbe considered under the additional weight and to avoid providing electrostatic shielding for the transmission of harmonic frequencies between the primary and secondary windings.
Of the transformer and the voltage variation:
WTG transformers are designed so that the voltage is regulated for the accuracy of the wind turbine output voltage. There is no capacity for intervention, voltage fluctuations, which are a common problem with wind turbines over trained 'in'. At the same time,The weather is monitored, the output current from the generator of milliseconds, allowing the limits of up to 5% surge for 10 seconds before being removed from the system. Therefore, the WTG transformer designed to match the generator output without overloading the size, design and WTG transformer must clearly robust to function without them
Obligation to withstand fault currents:
In general, the traditional distribution transformers, transformers andother types of transformers step-up 'drop out' when exposed to a fault. Once the error is corrected, the distribution transformer is brought back online. Generators for wind turbines to separate from the other side, to maintain the stability of the system does not allow it, developed from the system due to network problems, except in some guidelines for the generation of plants. The period of time the generator must remain on the line can vary. During this time, the generatorstill an unusually low voltage transformer supply to the WTS. Therefore, errors in the transformer, the design for the lowest 15% rated voltage for several cycles and then raised again to full voltage for a few seconds of an outage can be. WTG transformer must be clearly designed with enough "strength" to withstand a short circuit current during the first complete cycle in which the mechanical forces exerted on the transformer maximum WTGWindings.
Conclusions:
The role of transformers in the system WTG wind energy today is unique, its design must be unique and robust. Do not trade long-term reliability and reduce total cost of ownership at low cost.
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