Wind Farm Transformer Design Considerations
Posted: Apr, 27 - 2011
Published: Apr, 29 - 2011
Format: application/msword
No Of Pages: 10 pages
Language: English
Abstract
Wind Turbine Step-up Transformers that boost turbine outputs from a few hundred volts to medium voltage distribution levels are failing at an alarming rate. This trend affects both liquid filled and dry type transformers. The purpose of this paper is to discuss the most likely causes of wind turbine step-up transformer failures experienced by developers and operators of utility scale, wind farm projects throughout the industry. Further, this paper will illustrate that wind turbine step-up transformers are unique enough in their requirements that conventional distribution transformers are not optimally suitable for this application.
INTRODUCTION
Since the earliest of times, mankind has harnessed the power of wind to perform work. Ancient explorers and seafarers were the first to recognize that by capturing the wind they could expand their horizons and extend their known trade routes into heretofore unimaginable and distant places. Those who stayed at home also used this new technology to do difficult, heavy and arduous work. The first known application was in Persia between 500 and 900 AD where vertical axis wind mills were developed to grind grain and pump water. Since this was an adaption of the mariner’s sails, the blades for the first mills used a similar construction. This was such a giant leap in technology that it spread throughout the known world and in 1219 AD the first documented wind mill was operating in China. Early agrarian projects in Crete demonstrated that when combined with other mills large irritation projects were possible. By the 14th century, the Dutch were using wind powered pumps to drain water from the lowlands of the Rhine River delta.
In modern times windmills, or turbines, are used primarily for generating electrical energy. The first wind powered generators usually served a local need, often supplying power for isolated equipment. However, today wind generated electrical energy provides a few percent of the United States’ national energy needs with plans to reach 20% in the near future. For this growth to happen, the power output from wind turbines needs to be gathered, stepped up to transmission voltage levels and passed across the nation’s interconnected power grid to the end users.
Large scale wind farms, with many wind turbines connected together, are becoming a common sight in our 21st century world. We are bombarded with images of wind turbines in all forms of print, broadcast and electronic media. The present expansion of wind farms is similar to the meteoric growth of Co-Generation plants a few decades ago. Unfortunately, this rush to install wind turbines has outstripped the usual equipment developmental learning curve, one in which new technologies mature by trial and error and equipment is developed over time that is well suited for the job at hand. In this modern day land rush to cash-in on wind energy, developers are often opting for lowest initial equipment cost rather than considering total cost of ownership. The failure of inappropriately specified equipment raises the cost of ownership and this cost is borne by the wind turbine owners and operators rather than the original developers. Nowhere is this more evident than in the wind turbine generator step-up transformers.
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