Small wind turbine and hybrid system

SMALL WIND TURBINE AND HYBRID SYSTEM

SMALL WIND TURBINES AND HYBRID SYSTEM

Upswing for last two or three years

Main drivers to its growth are:

– Demand supply gap in energy;– Increase in fossil fuel prices;– Diverse applications for which it can be used both for standalone and grid tied.

Useful for powering small loads at remote locations particularly having weak or no grids.

Useful for commercial application – Telecommunication towers

Can serve as miniature power plants

SMALL WIND TURBINES/AEROGENERATORS

• Based on rotor swept area

• Based on axis of rotation

• Based on direction of wind

• Based on forces acting on rotor

CLASSIFICATIONS:


Rated power (kW) Rotor swept area (m2)

Sub-category

Prated < 1 kW A < 4.9 m2

(1.25m Dia)Pico wind turbine

1 kW < Prated< 7 kW A < 40 m2

( 3.6m Dia) Micro wind

turbine

7 kW < Prated< 50 kW A < 200 m2

( 7.9m dia)Mini wind turbine

or SWT

Based on rotor swept area:

Standard referred IEC 61400-2 – Design requirements of small wind turbines.

- Defines small wind turbines as systems with rotor swept area smaller than 200 sq.m, generating at a voltage below 1000 V a.c or 1500 V d.c.


Based on axis of rotation

Horizontal Axis Wind turbine

• Propeller type rotor is mounted on a horizontal axis.

• The rotor is positioned into the wind direction by means of a tail wane or active yaw motor

Vertical Axis Wind turbine

• Omni directional • No yaw mechanism required • Gearbox and electrical generator housed

near the ground• Requires guy wire support• Power output cannot be controlled during

high winds by changing the blade pitch

Darrieus Type Savonius Type

Horizontal Axis Wind turbine

http://www.symscape.com/node/403

http://www.symscape.com/node/403

Upwind Machine


Based on direction of wind:

• Rotor faces the wind • Avoid wind shades behind the tower

Downwind Machine• Rotor is placed on the lee side of the tower• Can be built without yaw mechanism• Rotor is more flexible and has less weight• Better structural dynamics

• Based on forces acting on wind turbine

• Lift Type • Drag Type

- If the tip speed ratio (TSR) > when then SWT has some amount of lift- If TSR < 1 then SWT is drag type

- Savonius rotors are drag type machine - Darrieus rotors are lift type turbine

Global Scenario:


In the year 2008, the total number of small wind turbine spectrum was 19000 units amounting to 33.6 MW installations.

Application World total by 2008

No. % kW %

Off-grid 13,902 73.48 7,536 22.5

On-grid 4,992 26.42 26,065 77.5

Total 18,89

4 100

33,601

100.0

Distribution of SWT installations in 2008, by applications


Indian Scenario

Total cumulative capacity of hybrid system is about 1110 kW

SMALL WIND TURBINES/AEROGENERATORSShares of States in Wind-Solar-Hybrid systems

SMALL WIND TURBINES/AEROGENERATORSOff-Grid / Standalone systems

Control schemes for variable speed operationConstant tip speed ratio scheme

T.S.R = ωR/V

• Wind speeds are measured locally and optimal rotor speed is computed using reference TSR.

• Optimal rotor speed is compared to the actual rotor speed and the electrical loading is adjusted to correct the difference.

Maximum power extraction using the constant tip speed ratio scheme


Control schemes for variable speed operationPeak Power Tracking scheme dP ---- = 0 dω

Maximum power extraction using the peak point extraction scheme

• Rotor speed is incrementally varied by small amount and by evaluating dP/dω the peak power tracking scheme continuously tracks the optimal operating point and adjust rotor speed accordingly


Photovoltaic System

Peak power tracking photovoltaic module


Peak Power Tracker

I-V Curve

Power output of the PV module is P = V · I watts. Operation moves away from the above point, such that the current is now I +∆Ivoltage is V +∆V, the power output will be

P + ∆ P = (V+∆V).(I+∆I)∆P = ∆V.I+V. ∆I At the peak point, ∆P = 0

is the dynamic impedance, and is the static impedance of the source

http://engnet.anu.edu.au/DEpeople/Andres.Cuevas/Sun/image/IVcurve.gif


Charge ConverterBuck Converter Step down DC to DC

converter

Voltage across the inductor

During ON time, ∆ IL. L = (Vin- Vout).Ton

During OFF time, ∆ IL. L = Vout .Toff

Vout = Vin.D

Where D is the duty cycle

D = Ton/T and T = Ton + Toff

Out put voltage is always < that of the input voltage


Charge ConverterBoost Converter

Step up DC to DC converter

Voltage across the inductor

During ON time, ∆ IL. L = Vin .Ton

During OFF time, ∆ IL. L = (Vout – Vin).Toff

Vout = Vin/1-D

Where D is the duty cycle

D = Ton/T and T = Ton + Toff

Out put voltage is always > that of the input voltage


Charge ConverterBuck Boost Converter

Buck and Boost converter combined together in cascading is the buck boost converter.

Buck boost converter used for variable speed wind machines for battery charging either by stepping up or stepping down the voltage


Battery

• Energy storage option used for standalone system

• Consists of electro-chemicals cells connected in series-parallel combination

to achieve the desired operating voltage and current.

• Cell capacity measured in Ah• Battery rating in specifically in terms of average

voltage during discharge and its Ah capacity.

• Charging a 600 Ah battery at C/10 rate means charging at 60 A.• Discharging that battery at C/2 rate means draining 300 A• Preferred batteries used for wind-solar-hybrid systems:

• Lead-acid (Pb-acid). • Nickel-metal hydride (NiMH).• Nickel-cadmium (NiCd).

SMALL WIND TURBINES/AEROGENERATORSGRID CONNECTED SYSTEMS

Grid connected wind system Grid connected PV system

ROLE OF C-WET

To evaluate the performance of the small wind turbines based on the following tests:

1. Power performance measurement 2. Duration test 3. Safety and function test

To empanel the small wind turbines with MNRE based on an evaluation of their safety philosophy, engineering integrity, quality assurance and results of the type tests (if conducted).

TYPE TESTING OF SMALL WIND TURBINES/AEROGENERATORS

TYPE TESTING

SAFETY AND FUNCTION TEST

POWER PERFORMANCE

TEST

DURATION TEST

OTHER TESTS(EMC,

ENVIRONMENTAL)

TYPE TEST CONFORMITY STATEMENT

The objective of the type test is to provide data needed to verify aspects which are vital to safety and therefore need additional experimental verification, and aspects which cannot be reliably evaluated by analysis.

SMALL WIND TURBINE TESTING SET UP

POWER PERFORMANCE TESTThe Power Performance is carried in accordance to the IEC standard, Wind Turbine Generator Systems, Part 12: Power performance Measurement Techniques, IEC 61400-12-1 DC power output of the turbine will be

measured. Wind speed Vs DC Power to be plotted. Power curve validates the manufacturer’s

performance claims over a range of wind speeds, aggregated over time.

Estimation of annual energy production helps in determining the amount of energy likely to be generated per annum, for a specific average wind speed.

0 2 4 6 8 10 12 14 16 180

100

200

300

400

500

600

700

Wind Speed (m/s)

Elec

trica

l Pow

er (W

)

2 4 6 8 10 12 14 160

0.02

0.04

0.06

0.08

0.1

0.12

Wind Speed (m/s)CP

DURATION TEST The purpose of the duration test is to investigate Structural integrity and material degradation Environmental / dynamic behaviour of wind turbine

Criteria satisfying the duration test as per IEC 61400-2 reliable operation during the test period for a minimum

period of 6 months of operation;

at least 2 500 h of power production in winds of any velocity; at least 250 h of power production in winds of 1.2 Vave and

above; at least 25 h of power production in winds of 1.8 Vave and

above.

SAFETY AND FUNCTION TEST The purpose of safety and function testing is to verify

that the wind turbine under test displays the behavior predicted in the design and that provisions relating to personnel safety are properly implemented.Power and Speed control – turbine has blade angle of 150 which regulates the speed of turbine• Yaw control - to check yawing / yawing movement

starts at a given wind speed• Loss of load – to check when the loads are removed

suddenly whether the turbine current reduces to zero.

• Over speed protection – to check how it regulates the speed of rotor. Turbine status will be sensed to verify if dump load switches on for RPM > 200.

• Start up – To check the automatic start up operation at a cut in wind speed of 2.5 m/sec.

• Shutdown above design wind speed – at 7 m/sec the machine starts furling.

• Emergency stop under normal operation – Time series of DC power, RPM, Turbine status signal will be plotted.

0

10

20

30

40

50

60

TimePo

wer

12 13 14 15 16 17 18 19400425450475500525550575600625650

Wind speed [m/s]

Max

pow

er

shut down above design wind speed

power and speed control

Wind Solar Hybrid Systems installed at C-WET

Small wind turbines in conjunction with solar photo voltaic system can be used in remote places( with weak grids and high winds) not connected to the grid, to meet the basic power requirements

Systems installed at C-WET Wind at C-WET : 4.0 m /s annual average Solar insolation : 700 W/ sq.m

(1) 25 kW Wind Solar Hybrid system(2) 5 kW wind Solar DG Hybrid System using intelligent

controller

25 kW Wind Solar Hybrid System Specifications:

15 kWp solar photovolatic system5 kW small wind turbines, 2 nos.Grid supported system288 V, 600 Ah battery back upAverage load 10 kWCost of the system : Rs 100 lakhs

Single line diagram of PCU

5 kW Wind-Solar-DG Hybrid System 5 kW Wind-Solar-Diesel Hybrid System- Proof of concept to provide uninterrupted power through intelligent, economical and optimized renewable sources - To monitor the generation, consumption and performance parameters through GPRS based remote monitoring.

Specifications: - Solar panel capacity: 1.8kW (peak)- Aerogenerator : 3.2 kW - Battery capacity: 48 Nos. of 600 Ah- DC link voltage : 48 V- DG set: 5 KVA- Cost of the system : Rs 20 lakhs

• Traditional megawatt power production in electricity is insufficient both for industrial growth and higher living standards.

• Micro-generation can act as a catalyst for cultural changes in consumer attitude.

• Output of solar photovoltaic system can be more reliably predicted, say 4 units/ day for 1 kW system.

• Small wind turbines need to be installed after a careful evaluation of the wind at the site, predicted output for the particular site and information on performance of the particular model.

CONCLUSION

THANKS

Small wind turbine and hybrid system

Technology

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