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Smoothing of Wind Farm Output using Short-Term ahead Wind Speed Prediction and Flywheel Energy Storage System

ROHITH PAULS7 FROLL NO: 46

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CONTENTSo INTRODUCTION

o NEED FOR SMOOTHING

o MODEL SYSTEM

o DIFFERENT MODELS OF SYSTEM

o SMOOTHING OF OUTPUT POWER

o WIND SPEED PREDICTION

o CONCLUSION

o REFRENCE

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INTRODUCTIONo Wind energy is now considered to be the world’s fastest growing renewable energy

o A Renewable Non-Polluting Resource

o Intermittent nature of wind speed makes a big issue in the generation of wind power.

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NEED FOR SMOOTHINGo Beneficial for power grid management

o Stabilization of power system

o Matching demand and supply

o To reduce frequency deviation in the grid

o Remove restrictions to install new wind farms.

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METHODSo Smoothing of output power of wind farm is achieved by:

Battery energy storage system (BESS),

super conducting magnetic energy storage systems (SME)

energy capacitor systems (ECS)

flywheel energy storage system (FEES)

o Forecasting of the wind speed using different techniques

linear regression analysis,

time series,

linear regression method

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MODEL SYSTEM

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DIFFERENT MODELS OF SYSTEM1. A. Wind Turbine model

2. Double Fed Induction Generator Model

3. FESS

4. Rotor Side Converter(RSC)

5. Grid Side Converter(GSC)

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WIND TURBINE MODELo Consists of an Induction Generator and a wind turbine

o The reference power of the WF is adjusted according to the availability of the stored energy in

the FESS

o Wind turbines produce electricity by using the power of the wind to drive an electrical

generator

o Wind turbine extracts kinetic energy from the swept area of the blades

o Generated power is fed to the supply system when the IG is run above synchronous speed

o Generated power is

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DOUBLE FED INDUCTION GENERATOR MODEL

o Modelled in the direct (d) and quadrature (q) axis reference frame,

FIG 2.

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Contd…o DFIG supplies the real power and it can compensate reactive power

o when rotor speed is greater than rotating magnetic field from stator, the stator induces a

strong current in the rotor

o power will be transferred as an electromagnetic force to the stator

o converted to electricity which is fed to the electric grid

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ROTOR SIDE CONVERTER(RSC)o Control the active and reactive power control of the stator side

o control the wind turbine output power and the voltage measured at the grid terminals

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GRID SIDE CONVERTER(GSC)o keep the DC link voltage constant at 1 p.u

o Supply additional reactive power into the grid

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FESSo DFIG with secondary excitation system is considered as FESS

o mechanical energy storage system where energy is stored in the form of kinetic energy.

o maximum and minimum energy that can be stored in the FESS is limited to ± 30% of

the rated energy

o The reference of the output power for the secondary excitation circuit is adjusted

according to the availability of the stored energy in FESS and predicted wind speed data.

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ADVANTAGES OF FESSoReliability

olong life

o large energy storage capacity,

oless overall cost

opower compensation is very effective.

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SMOOTHING OF OUTPUT POWER BY USING FESS

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Contd…o reference output (P_ref_1) is generated using low pass filter function

o When the output of the IG is higher than the final output power reference, FESS is in

charging mode and absorbs the active power from the grid.

o when the generated output is lower than the final output power reference, FESS is in

discharging mode and supplies active power to the grid.

o By controlling the rotor speed of FESS in different operating regions, the stored energy in

FESS is utilized to smooth the output power fluctuation

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WIND SPEED PREDICTION BY USING LINEAR REGRESSION

MODELo Wind speed data is predicted using short-term ahead linear regression model

o The prediction model has been implemented using MATLAB.

o Predicted power is given by:

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Contd…o If predicted power (P_Predict) - actual power (P_IG) is small output power reference remain

unchanged

o P_ref_2 is corrected if the actual stored energy of FESS is not in a range of (45-85)%

o this control scheme will prevent the system from reaching instability

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FLOWCHART

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Contd…o Flowchart is used to modify the final output reference (P_ref_final)

o if the rotor speed of the FESS (W) is ≥1.3 p.u. or it is ≤ 0.7 p.u ,no power will be absorbed or

supplied by the FESS.

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CONCLUSIONo Proposed a new control strategy of FESS to mitigate the fluctuation in the output power of the

grid

o It has been shown that prediction of the wind speed and modification of the output power

reference accordingly makes the FESS more effective and reduces the fluctuation of output

power efficiently.

o The system cost can also be kept minimum by optimum use of small capacity flywheel energy

storage system

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REFRENCESo “ A New Control Strategy for Smoothing of Wind Farm Output using Short-Term Ahead Wind Speed Prediction

and Flywheel Energy Storage System” Farzana Islam1, Hany. Hasanien2, Ahmed Al-Durra1, S.M.Muyeen1

o X. Wang, G. Siderators, N. Hatziargyrion and L. H. Tsoakalas, “Wind Speed Forecasting for Power System

Operational Planning,” International Conference on Probabilistic Methods applied to Power System, pp 470-474,

o S.M. Muyeen, M.H. Ali, R. Takahashi, T. Murata and J. Tamura,“Wind Generator Output Power Smoothing and

Terminal Voltage Regulation by Using STATCOM/ESS

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