The EW15 wind turbine consists of a 15 meter rotor which produces 50 kW at an 11.3 m/s wind speed (60 Hz model). The turbine was developed in conjunction with the U.S. Department of Energy and the National Renewable Energy Laboratory (NREL) under their Advanced Wind Turbine (AWT) Program. The goal of this cost shared program was to produce economic wind generated electricity in a moderate average wind resource. This was achieved with simplicity in design, high availability and failsafe reliability.

The philosophy of Atlantic Orient Corporation is reflected in every stage of machine development. We have taken a long term view of our market and product development. Each component of the machine was designed and tested to ensure that actual field performance meets or exceeds design specifications. We have successfully designed a state-of-the-art wind turbine generator and have proven results from our current installations.

The EW15 wind turbine was developed with a series of R&D cost-shared contracts administered by the National Renewable Energy Laboratory to comply with International Electro-Technical Commission standards. The Dutch Laboratory ECN has conducted a Failure Modes Effects Analysis (FMEA) on the EW15 wind turbine. Field testing continues in several locations in the United States and Canada, as well as component qualification testing in our Fairlee, Vermont and Prince Edward Island, Canada facilities.

U.S. Department of Agriculture Test Site Bushland, Texas

National Wind Turbine Test Center Boulder, Colorado

Atlantic Wind Test Site Prince Edward Island, Canada

Greek National Laboratory (CRES) Near Athens, Greece

One of the most important safety criterion in the design of the EW15 is the ability to safely control the wind turbine in normal and extreme conditions. This has lead to the development of redundant failsafe control mechanisms. The ultimate goal above and beyond low cost and high reliability is the protection and safe operation of the wind turbine in all specified conditions

In conjunction with the U.S. Department of Energy and the National Renewable Energy Laboratory's (NREL) Advanced Wind Turbine Program, Atlantic Orient Corporation developed a next generation 50 kW wind turbine based upon the concept of simplicity. By adhering to a design philosophy, this turbine produces energy at competitive rates for distributed generation, village electrification, diesel based utilities and purchased power displacement for agriculture, industry and municipalities.

From 1982 through 1986 approximately 750 Enertech wind turbines, designated as the E44 series, were installed in wind power stations throughout the United States and several other countries (most of them are still operating today). Atlantic Orient Corporation evaluated the historic performance of a significant number of the E44 series wind turbines. Problem areas were identified and rank ordered according to their contribution to turbine downtime. Specific potential solutions to downtime related problems were conceptualized and the impact of the various options was evaluated on an economic and risk basis to further define the benefits of each candidate improvement.

As a result of this analysis, Atlantic Orient Corporation developed the preliminary design of a 50 kW wind turbine designated the EW15. The results of this effort were so encouraging that final design and prototyping of the EW15 were initiated under separate NREL contracts. The Dutch National Laboratory for Renewable Energy (ECN) performed an independent reliability analysis and concluded that the EW15 was of fundamentally sound design.

Turbine and Component Qualification Testing

After an extensive review and analysis of the operating history of existing wind turbines, AOC's design team incorporated many design features in the EW15 which enhance energy production. These features include the following:

• Advanced Modified NREL Thick Airfoils
• High Strength to Weight Ratio Wood/Epoxy Blades
• Electromagnetically Controlled Tip Brakes
• Single Piece Hub Casting
• Innovative Split Core Rotary Transformer to transfer power to the Tip Brakes
• Integrated Gearbox with Improved Internal Components
• Totally Enclosed Generator
• Single Piece Cast Tower Top with Larger Yaw Bearings
• Uniformly Tapered Galvanized Lattice Tower
• Enhanced Dynamic Brake
• Advanced Controller based upon a Programmable Logic Controller

R&D Undertaken with NREL/DOE for 15/50

The 15/50 designation refers to the 15-meter wood/epoxy rotor and its rated output of 50 kW at 11.3 m/s wind speed in the 60 Hz version.

The tower top casting provides a rigid, low cost solution to interfacing the gearbox with the tower. The low speed shaft has sufficient diameter and material strength to accommodate the structural and fatigue loads. The hub consists of a single piece casting, again, focusing on design simplicity.

Our design team has fulfilled the goal of design simplicity. The heart of the design is the integrated gearbox, which consists of a single piece, cast housing. The generator is flange-mounted to the planetary gearbox with the parking brake directly coupled to the totally enclosed generator. There is no nacelle.

The design of the dynamic brake is based upon the proven design used on the Enertech E44 turbines. However, brake design has been significantly enhanced through our use of the Alternative Transient Program (ATP), software that models electromagnetic transients. This design package has been validated through extensive bench testing. A passive resistor-capacitor network is connected to the output of the generator. The brake is operated from the control system and is triggered by either detection of faults or by high wind speed. As the result of our control strategy, the frequency of operation of the dynamic brake is greatly reduced which decreases the resulting stresses on the generator and transmission.

The EW15 aerodynamic tip brakes are electromagnetically latched and released based upon instructions from the control system. In the normal stopping mode, both the dynamic brake and the tip brake are deployed simultaneously. All components are designed for fail safe operation. A spring/damper is incorporated to soften deployment of the tip brakes.