Technologies That Really Capture Wind Energy

Energetic Drives sees lots of promise and potential in the Wind Energy sector.  With a flood of companies trying to produce small wind turbines for residential use and a few select giants staking out the turf from 1.5 MW and up, there is a large niche in the middle that is being ignored.  Using efficient technology solutions with new or refurbished wind turbines, Energetic Drives is positioned to provide quality electricity at affordable prices.  

Energetic Drives entered the medium-sized Commercial/Industrial wind turbine sector after noticing this segment provided the perfect opportunity to highlight our permanent magnet motor/generator and Grid-Tie inverter technology.

The traditional wind turbine converts the kinetic energy captured by the blades, causing rotation on the main drive shaft of the wind turbine. This shaft is coupled to an induction generator via a large ratio, multi stage gearbox (see Figure 1 above).

This is necessary in order to achieve the rotation speed on the generator to produce power at 50 or 60 hz dependent upon which country you are in.  

Traditional induction generators require the generator to be running 900, 1200, 1500 or 1800 rpm at the generators shaft and, with some conditioning by the control electronics, 50 or 60 hz can be produced over a small range of speeds.  Due to this inherent limitation, these turbines are commonly known as "fixed speed" turbines.

Another method used to maintain these fixed speeds are the introduction of variable pitch blades that manipulate the efficiency of the blades thus keeping the RPM's in a suitable bandwidth over a wider range of wind speeds.

With the introduction of the Energetic Drives, grid-tie inverter, the induction generator is able to take a very large envelope of wind speed and continuously produce 60 hz power, perfectly synchronized with the grid power at 60 hz. This is achieved by introducing an inverter and converter to the electrical generation circuit grid-tie inverter (see Figure 4).

 

The converter takes the grid power from the input line and converts/charges the DC bus voltage to a base level and, while doing this, the converter also monitors the cycles of this incoming voltage.   At the same time, the inverter powers the generator and presets multiple current limits to the generator. Once the kinetic energy produced by the wind turbine exceeds the preset limits throughout the wind turbines range, AC energy is produced by the generator. Immediately, the inverter takes this energy and charges the DC bus.  The converter senses the increase in the DC bus and immediately converts this energy to 480 volt 3 phase AC.  This energy is synchronized to the incoming AC Power and switched onto the grid.  Due to this process, 480 volt 3 phase energy at 60 hz is produced throughout the operating range of the wind turbine, thus erasing the fixed speed limitation.

Note there is a cube function that applies to the wind energy presented to the turbine and the power produced by the induction generator.

 

Adding a grid-tie inverter increases the power generated over a given period of time with a unity power factor.  Add to this the IEEE 519 compliant Total Harmonic Distortion (THD) at less than 3%, and you will agree that the introduction of the grid-tie inverter into your traditional schema will keep the clean power police at arms length and stop you from getting penalized for producing reactance power (KVARS).  IEEE 1547 compliance was just granted to this grid-tie inverter design. 

A fully integrated solution for your consideration comprises of the Grid-Tie Inverter and the introduction of our Permanent Magnet AC Generator (PMAC).
 
 The PMAC is a motor with 24, 36 or 48 poles and base speed ratings of 60-500 rpm. When this generator is employed with the Grid-Tie Inverter it affords us the luxury of removing the multi-stage high ratio speed multiplier gearbox. The ratio necessary for implementing the PMAC generator is only 3.866:1.

There is a noticeable absence of audible noise coming from the Nacelle. You will also note the PMAC generator is substantially smaller in size than the equivalent induction generator (compare Figures 7 & 8 to Figure 9) and is clearly better matched to the rotational specifications of the wind turbine itself.
 The core of the generator is of a rare earth magnet construct which produces large magnetic flux density in the stator that, when coupled to the turbine rotor, provides a substantial increase in power realized at all given speeds of the wind.  When a cooling system is applied to the generator in the form of a glycol cooling jacket the constant ratings of 110-120% are realized.  The ability to overdrive the generator at optimum wind speeds, results in greater power production, providing a greater return on investment for a given power size.  For those momentary gusts of winds, the PMAC generator is able to withstand 180% of the rated power without tripping out the grid tie inverter. 

On systems over 400 KW and up to 1.5 MW, Energetic Drives has designed a special “sun gear” implementation, courtesy of our Chief Engineer Semion Stolyar, PhD, holder of over 70 patents world-wide.  This design allows a single turbine rotor shaft to rotate up to four generators at a time.  The generators are coupled to the shaft through this gearbox, providing up to a 1.5 MW power generation system for most medium size wind turbines.  The total noise produce by our multiple generator technology is less than 100 decibels.

The net result, is a power electrical generation system that produces unity power factor energy throughout a larger wind speed range.  Utilizing reduced ratio gearboxes coupled to the PMAC generators has a profound effect on the mean time between failure (MTBF) of the wind turbine mechanical components.

When the Grid-Tie Inverter is introduced into your system with an existing induction generator or a PMAC generator, the grid feeder lines are completely isolated against any reactance from the generator.

At any time the generator can be switched to a motor control function where the system can implement a controlled deceleration to a parked condition as sensors dictate, thus reducing the massive stresses incurred during emergency stop procedures.