Renewable energy technologies have seen consistent development so that today, it is a part of mainstream power generation. Apart from being ‘clean’ and ‘green’, renewable energy has also proven to be reliable and cost-effective. Wind energy, along with solar energy, has seen immense growth over the last decade and dominated renewable energy generation.How is Wind Power Generated?
Wind power is generated using wind turbines. A simple wind turbine is made up of three essential parts:
1. Blades: The blades of a rotor are moved by wind, causing them to move. Thus, energy is passed on to the rotor.
2. Shaft: The rotor is connected to a shaft which also spins when the rotor moves.
3. Generator: The shaft moves transfers the rotational energy to a generator which produces electricity. The three types of generators that can be used for wind power generation are - DC generators, AC synchronous generators, AC asynchronous generators.
To get the most out of wind power generation, larger and larger turbines are being used. Several wind turbines are installed in open spaces which are at a higher altitude in order to get unobstructed wind to power these turbines.
Design considerations for Wind Turbine Generators.
Some of the considerations while designing a wind turbine generator are as given below:
Turbines can be fixed-speed or variable-speed. It makes sense to run turbines at variable speed, even though the capital costs may be higher. Operating the turbine at variable speed gives the flexibility to run the turbine efficiently even when the wind is at below the rated speed. Variable speed also has the below advantages:
- Reduces aerodynamically generated noise
- Reduces the risk of physical damage and fatigue in the system
- Reduces mechanical stress fluctuation on the machine shaft
- Enables separate control of active and reactive power and power factor
For operating at variable speeds, differential gear boxes are used. Alternatively, continuously-variable transmission systems are employed.
Drive of the Turbine:
The drive of the turbine can either be direct or geared. Direct drives are preferred since they offer better reliability in addition to avoiding the need for having gears. However, direct-drive turbines result in low operating speeds.
In geared drive, the generator speed depends on the gear ratio. But, this drive is prone to failures, especially if the wind turbines are in harsh environmental conditions.
Topology – Brushed or Brushless:
Brushed topology warrants more efforts towards maintenance. Since wind turbines are located at remote locations that are difficult to access, systems that do not require much maintenance are preferable. It also offers better reliability.
The Converter Type:
The three types of converters used in wind power generation are:
Two-level converter:They use two voltage source inverters and a DC capacitor. But these converters are expensive and suffer from high switching loss.
Multi-level converters: They use more than two voltage levels. They have lower switching loss compared to two-level converters. They also provide better voltage capacity.
Matrix converters: They are best suited for AC to AC conversion without the need to have a DC stage in between. This means they are lower in size as well as cost. They also offer reliability, even though the conducting power loss is on the higher side.
The trend towards generating more power through renewable sources and the growing demand for power in the world has brought wind power generation into the limelight. Today, wind power generation systems are robust, more efficient, and efforts are on to make it more economical.
From power generation to making the power available for use, large cable assemblies are used. With the use of cables, comes the need for high-quality connectors. Since the connectors are used in outdoor conditions they are exposed to harsh environmental conditions. Also, the remote location of wind power generators means that connectors that are reliable and require less maintenance are preferred.