Anatomy of Modern Wind Turbine & Wind farms -II P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Arganons of a Machine to Generate Lift for Power generation

General Configurations of Horizontal-Axis Wind Turbines

The Power-Train Subsystem Speed-increasing gearboxes remain the dominant design approach for large-scale HAWTs.

The Nacelle Structure Subsystem Bed plate assembly HAWT nacelle structure is the primary load path from the turbine shaft to the tower. Enclosure yaw drive mechanism

General Configuration of a Vertical-Axis Wind Turbine

The Turbine Rotor Subsystem : VAWT Blades are shaped to approximate a troposkien (from the Greek for “turning rope”) This shape generates zero bending stress.

The Power Train Subsystem : VAWT VAWT power-train components are located at or near the ground. The VAWT turbine shaft assembly carries axial and torque loads only with no bending loads. VAWT gearboxes, generator-drive shafts, and generators have the same general configurations as HAWT power-train components.

Layout of A Wind Farm

Structure of Wind Farm: HVAC Macro Structure of A Wind Turbine Macro Structure of A Wind Farm (HVAC)

Structure of Wind Farm: HVDC

The power in the wind The power in the wind is proportional to: the area of windmill being swept by the wind the cube of the wind speed the air density - which varies with altitude The formula used for calculating the power in the wind is shown below: where, P is power in watts (W) ρ is the air density in kilograms per cubic metre (kg/m3) A is the swept rotor area in square metres (m2)

Vertical Profiles of the Steady Wind Logarithmic/Linear Law for Vertical Profiles of Wind Speed U* = friction velocity (m/s)  = von Karman constant, approximately equal to 0.4 z = elevation above ground level (m) z0 = empirical surface roughness length (m) s( ) = atmospheric stability function dependent on z/Ls (m/s) Ls = Monin-Obukhov stability length

Aerodynamics for Selection of Tower Height

Distribution of Wind Speed Two probability distribution functions are commonly used for wind speed. The simpler of the two is the Rayleigh distribution which has a single parameter c. c = Empirical Weibull scale factor (m/s) The Weibull distribution shown below has two parameters k and c. The Rayleigh distribution is actually a special case of the Weibull distribution with k = 2.

True Wind speed duration curves

True Functions to Model Distribution of Wind Speed The Rayleigh distribution is a special case of the actual wind distribution. Duration curves for several real site wind profiles may be obtained by using a factor k . The range from 1.5 to 3.0 for k includes most site wind conditions. The Weibull distribution has two parameters k and c. The Rayleigh distribution is actually a special case of the Weibull distribution with k = 2.

Wind speed duration curves according to the Weibull distribution model

Most probable value of velocity For the Rayleigh distribution the single parameter, c, relates the three statistical properties:

Wind turbine performance An actual wind turbine is only operated in a range between a minimum velocity, called the cut-in velocity, and a maximum velocity, called the cut-out velocity. The power coefficient, cp, is defined as the fraction of the wind power that is actually captured. If the potential output power of the wind turbine is more than the maximum input power to the generator, the turbine is controlled to produce only the maximum generator power. Average power output from the wind turbine, for a given probability distribution.

Distribution of Wind Turbine Power

Wind Power generation for developing countries Unlike the trend toward large-scale grid connected wind turbines seen in the West. The more immediate demand for rural energy supply in developing countries is for smaller machines in the 5 - 100 kW range. These can be connected to small, localized micro-grid systems and used in conjunction with diesel generating sets and/or solar photovoltaic systems. The main area of growth being for very small battery charging wind turbines (50 - 150 Watts). In Inner Mongolia there are over 30,000 such machines used by herders for providing power for lighting, televisions, radios, etc. Other applications for small wind machines include water pumping, telecommunications power supply and irrigation.

Smart Grid India

Some key features of a smart grid are Self-healing: sophisticated grid monitors and controls anticipate and instantly respond to system problems in order to mitigate outages or power quality problems. Secure from natural and man-made threats: smart-grid technologies will facilitate identification of and response to deliberate or natural disruptions. Enhanced control by customers: a smart grid allows consumers greater control of the appliances and equipment in their homes and workplace by interconnecting the energy management systems in smart buildings and thus enables consumers to lower their energy consumption. Asset optimization: Smart grid optimizes assets while minimizing the cost of operation and maintenance.

Cost Analysis of A Wind Turbine Aerodynamic modeling is used to determine the optimum tower height, control systems, number of blades and blade shape. Conventional horizontal axis turbines can be divided into three components. The rotor component, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low speed rotational energy. The generator component, which is approximately 34% of the wind turbine cost, includes the electrical generator, the control electronics. The structural support component, which is approximately 15% of the wind turbine cost, includes the tower and rotor yaw mechanism.

Reality of Capacity Vs Size