Metro Power company ltd Project
Wind Turbine Generator "WTG"
Metro Power Project consists of 20 Wind Turbine Generator units with the following design parameters:
| WTG Make / Model | Nordex N100 |
|---|---|
| Name-Plate Capacity of each WTG | 2.5 MW |
| Name-Plate Capacity of the Wind Farm | 50 MW |
| Turbine Class | IEC Class II A |
| Net Annual Energy Production | 142GWh |
WTG System Specifications
Each WTG comprises of the following components
1 - Rotor
| Diameter: | 100 m |
| Swept Area: | 7857square meters |
| Number of Blades: | Three |
2 - Blade
The WTG consists of three blades made of glass fiber-reinforced polyester; the length of the blades is 48.7meter. The blades are directly bolted to the hub.
3 - Hub
The hub is fixed to the rotor shaft which drives the generator through a gearbox. The blades are directly bolted to the hub and hence are controlled by the help of motors installed inside the hub.
4 - Gearbox
Main WTG gearbox is a planetary helical type.
5 - Yaw system
The yaw drive is an important component of the horizontal axis wind turbines’ yaw system.
The yaw system comprises of geared motors and brakes. The yaw drive is used to keep the rotor facing into the wind as the wind direction changes.
6 - Nacelle
The nacelle is made of fiber-reinforced plastic and designed in a way to protect internal components against various ambient conditions. It also ensures adequate noise dampening.
7 - Tower
The tower height of every WTG is 80 meters, equipped with internal tower ladder along with safety harness & elevator. The tower supports the nacelle assembly which holds the hub along with the blades.
8 - Generator
Type description Double-fed asynchronous (induction) generator, wound rotor, four-pole
| Rated power | 2500 kW |
| Voltage (stator) | 660 V (phase to phase) |
| Frequency | 50 Hz (48.5 – 51.5 Hz) |
| Stator& rotor winding | Star |
| Protection class (Generator) | IP54 |
| Thermal classification | Class F |
Auxiliary Plant Facilities
Metro Power Project consists of 20 Wind Turbine Generator units with the following design parameters:
a - Grounding System
The Grounding system is erected together with the foundation. The foundation grounding is designed in accordance with IEC 61024. Safety for persons: The ring grounding reduces the shock hazard voltage for persons being near the tower foundation during a lightning stroke. Operational safety: The deep grounding guarantees a low and stable earth resistance for the whole grounding system.
b - Lightning Protection
The lightning and overvoltage protection for the overall system follows the concept of lightning protection zones and is based on the standard EN 62305 The wind turbine is equipped with a complete external and internal lightning protection system considering a direct lightning stroke. The external lightning protection system is connected to the foundation ring grounding system and thus guarantees that any lightning currents are safely deflected to the ground.
c - Fire Protection
Most components of the wind turbine generator system are predominantly metal. This applies, for example, to the tower, the machine supports, shaft, gear unit, hydraulic unit, brake, generator, clutch, drives, etc.
A temperature sensor is installed in the machine house and measures the temperature inside the machine house. If a certain limit value is exceeded, a warning message is sent automatically to the remote monitoring office and the system is automatically shut down.
Environmental Requirements
Metro Power Project complies with the environmental requirements of the Sindh Environmental Protection Agency (SEPA). Nordex N100 state-of-the-art turbine technology particularly ensures that the noise generated by the Wind Turbine Generator System is within regulatory limits.
d - Electrical Layout:
The installed Wind turbines use Asynchronous generator whose shaft relates to a gear box which is coupled with Hub blades. The WTG produce 660 Volts, which after synchronization thru a frequency converter is stepped up to 22kV thru Generator step up transformer installed with each turbine.
All 20 WTGs are divided into Four WTG groups, each group consisting of 5 WTGs. Each WTG is connected with its own Ring Main Unit switchgear. The voltage produced by each WTG is fed into system thru Ring Main unit switchgear is interconnected with other RMUs by underground power cables and fed into MV substation at the site.
The 22Kv is then stepped up thru two power transformers up to 132kV & then power is evacuated into 220/132kV New Jhimpir Grid station at inter-connection point.
e - Anemometry System
The anemometry system comprises of two Wind Masts, installed at wind power plant site, one wind mast is situated at the South-East side and the other at North-West of the wind farm.
Each Wind Mast is 80 meters high, which is equivalent to the turbine height and is mounted with two Data loggers These data loggers are calibrated in accordance with applicable standards; the main function of the anemometry system is to accurately measure and record Wind Speed, Wind Direction, Ambient Temperature, Humidity and other necessary information relevant to the site conditions. This information is monitored and transmitted at the same time to many set locations.
Condition Monitoring System
Each Wind turbine generator is equipped with a condition monitoring system, consisting of a set of vibration and speed sensors installed at critical locations in the WTG like gear box, generator shaft, generator and rotor bearings. Inputs from these sensors are fed in to a controller, which compares the instantaneous measured data with set point values, recorded during initial months of WTG operation, and generates alarm signals in case of deviation to prevent possible future wear and errors.
All the measured data from sensors is archived in a database for post analysis of WTG condition.