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Simulation Model of with Induction Generator

1 2 Lie Jasa , Mochamad Ashari1, Ardyono Priyadi2, Mauridhi Hery Electrical Engineering Department Purnomo3 1 Udayana University Electrical Engineering Department Bali, Indonesia 2 Sepuluh Nopember Institute of Technology Sepuluh Nopember Institute of Technology Surabaya, Indonesia Surabaya, Indonesia 1 2 1 2 [email protected], [email protected], [email protected], [email protected] [email protected]

Abstract—Conventional energy sources used these days comes developed in various studies and experiments [1], [6], [11]. On from the limited energy resources that will be exhausted in the this paper, the simulation of Matlab showed a wind turbine near future. Research on wind energy as one of the renewable connected to an induction generator with characteristics of energy sources has been promoted by researchers in many wind speed (V-wind), Pitch lade (β), blade speed ratio (λ), countries around the world. Wind energy approach is a potential performace coefisien turbine (Cp), mechanical power output resource of energy and environmentally friendly. However, the main constraint in studying it is the wind cannot be regulated (Pm), the current output (I2C), and power generator output because it changes in speed at all times in accordance with the (Pw). wind guts. The present study aimed to determine the characteristics of wind turbine that were connected with II. PLANTS MODEL induction generator by applying simulation technique using A. Wind Turbine. Matlab. The results showed that by using the maximum wind speed of 12 m/s with the pitch angle β = 0 degree, the mechanical Wind turbine is a turbine that is used to convert kinatic energy output power (Pm) is 25513942.39 watt. When the pitch angle β of wind into electrical energy. Theorerically, the stronger the was increased up to 11o with the maximum wind speed, the Pm wind blows, the greater the was generated dropped to 10168366.36 Watt. Moreover, the induction generator [12, 13, 14]. When the mechanical energy is connected to an output current of I2C with the maximum wind speed and at λ induction generator, the rotation of wind turbine rotor will value of 8 is the maximum current produced by the generator. move from induction machine and will produce an output The computing processes and outputs, and the stages of wind voltage in the known as electrical energy. Wind turbine energy installation are discussed in details. is originally created to meet the needs of farmers in making Keywords – Wind turbine, Renewable, Wind energy, blade. rice mills, agricultural irrigation purposes and etc. Many wind turbines that are known to many people over the years are built in Denmark, the Netherlands and other European countries called as the windmill [12, 13]. I. INTRODUCTION

The energy crisis faced by all countries in the world nowadays Wind turbine is windmill that is used to generate electrical is due to the limitations of conventional energy sources such energy. Due to the limited energy resources such as oils and as oils, and gases that have been used. The excessive coal, wind turbines are developed to accommodate the energy use over the years gives impact on air pollution, global electrical energy needs of the community. Water, wind and warming and climate change. Almost all countries in the sunlight are sources and the sources are not world today are competing to conduct research on wind limited [12, 14, 15, 16, 17]. Although to date the construction energy that is used as one of the policy option in the future of wind turbines has not been able to compete with energy development. Besides, it is an environmentally conventional power plants, studies on wind turbine are being friendly, green, unlimited and renewable energy sources, the developed by scientists because of the realization that in the wind energy is less cost competitive. This was proven when near future humans will be faced with the problem of shortage the installation of wind turbines in parts of the world increased of natural resources to generate electricity. by 30% and wind turbine generator industries like in china have more than 80 producers [1], [2], [3], [4], [5].

The main problem faced by researchers in the world today is the nature of the wind always changes and the speed can not be regulated. Consequently, the sustainalibility of wind energy resources is still not able to compensate for conventional energy generation. The wind energy therefore should be

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There are two types of wind turbines [13,14,15]. (1) Propeller where Pm is the mechanical power output of the turbine, Cp is wind turbine with horizontal axis. This wind turbines should the performance coefficient of the turbine, λ is the ratio of the be directed in accordance with the highest wind direction speed of the rotor blade to the wind velocity, and β is the blade speed, and (2) Darrieus wind turbine is a type of vertical axis pitch angle (degrees). Coefficients C, then respectively are C1 wind turbine discovered by GJM Darrieus in 1920. The = 0.5176, C2 = 116, C3 = 0.4, C4 = 5, C5 = 21, and C6 = advantage of this type of wind turbine is around the turbine 0.0068 [12]. Cp-λ characteristics, for the pitch angle β, is does not require mechanisms on wind direction [14]. assumed to be lower. The maximum value of Cp is 0:48 (CPmax = 0.48), for β = 0 ° and for λ = 8.1. The main supporting components of a wind turbine that can By connecting between λ and β, and λ –next values of λ- lamda generate electrical energy, are as follows [14]. (a) Gearbox: i values will change and keep changing in every moment. The serves to change the low round on the mill into high rotation; equation is expressed by: (b) Brake System: is used to keep the rotation on the shaft after the gearbox in order to work safely at the point when a large wind speeds, to avoid overheating, breakdown rotor, 1 1 0.035 wires at the generator end; (c) Generator: is used to convert   3 (4) the kinetic energy into electrical energy; (d) : i   0.08  1 serves as back-up electrical energy when the load increases or the use of electrical power when the wind speed of a region is diminishing; (e) Rectifier-inverter: rectifier can rectify B. Generator Induksi. Induction generator sinusoid wave (AC) produced by the generator into a wave The working principle of the equivalent circuit is to use DC while Inverter has the opposite function; (f) Sensors: wind electromagnetic induction [15]. Primary and secondary turbines can be used to direct the wheel position (blade) in the sections can be described by an equivalent circuit as shown in direction of the wind, so the windmill rotates though the wind Figure 1. is always changing; and the last (g) Wind turbine safety system: is a lightning rod that serves as a protection from R' R X 2 X ' lightning strikes 1 1 2 I  I'2 The formula of the power of wind turbine input is given by X 1 S Rc m R'2 ( ) [12]: S 3 Pm = 1/2 ρAV wind (1) where Pm is the power generated by wind, ρ (Rho) is the air density (kg/m3) and is of 1255 kg/m3, A is the area of a circle Figure 1.Equivalent circuit of induction generator in the wind turbine blade (m2), and Vwind is wind speed in m/s. By using Thevenin's theorem, the voltage at point X and Y

generates equation V1 = Vt - Io (R1 + jX1), so a substitute While the equation for the wind turbine output [12] is that a circuit can be illustrated as Figure 4. model of wind turbine connected to an induction generator is theoretically generate output equation as shown in equation R' R X 2 X ' (2): 1 1 2

I I' 3 2 Pm = Cp(λ,β) 1/2 ρ A V wind (2) 1 S R X R' ( ) -C5 c m 2 C S Cp(,) = C ( 2 - C  - C )e i  C  1  2 4 6 i (3)

Figure 2. Substitute circuit of induction generator

I2C current flowing through R2 'and X2' with R2 load changes will directly be related to the slip that occurs between the rotor and stator of an induction generator [15]. Connected flow equation is shown in formula 5.

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Figure 4. Parameter input of wind turbine model V I  1 2 c R 2 c 2 2 ( R 1  )  ( X 1  X ' 2 ) Maximum mechanical power turbine will be simulated using S (5) Matlab software.

The output power of induction generator is a square of output III. METHODOLOGY current with I2C on the load resistance value R2C, so the power out equation becomes equation 6. To compute a simulation using Matlab, this study proposed the stages for calculating the maximum mechanical power output of wind turbine, as follows: 2 1 S Pm  3(I 2c ) R2c ( ) (6) S Based on the major and supporting components of wind 1. Analyzing the process of wind turbines, V-wind, pitch turbine, and the formula 1 to 6 discussed above, the present angle (β), the turbine swept area (A), and the wind researchers proposed a model wind turbine with induction density (ρ). The wind turbine work is based on wind generator as shown in Figure 3. speed to be converted into mechanical energy.

2. Breakdown the wind turbine with the radius of turbine, which is wind density (rho) = 1225 kg/m3, and the area A = 12.5663 which the radius is assumed 2 meters, the value of the equation (4) parameter of C1 = 0.5176; C2 = 116; C3 = 0.4; C4 = 5; C5 = 21; C6 = 0.0068 3. Analyzing the output of equation (2), (3) and (4) to obtain the value of mechanical power output (Pm) of the turbine, then Pm will be entered into the equation (5) of the equation of induction generator. 4. Having inserted the value of Pm, then the value I2C can be calculated by the equation (5). Having the value I2C, the output power then can be calculated by the formula Pout = (I2C) 2 R2C in equation 6.

IV. SIMULATION RESULTS Figure 3. Model of wind turbine with induction generator control Simulation model of wind turbines in this study uses Matlab Wind turbine model in Figure 3 uses the parameters of R2009b. Performance coefficient (Cp) was computed by the wind speed (V-wind) that always changes; pitch angle (β) is the value of λ from 0 to 15 and the value of β from 0 to 20 as in blade angle that can be changed to compensate for wind speed; Figure 4. Cp with a value of β 0.5, 10, and 15 is shown turbine swept area (A) is the area while it rotates blade area , separately in Figure 5. and the wind density (ρ). All the parameters are used as input to obtain the turbine mechanical power (Pm) as shown in As can be seen, Figures 4 and 5 show that the greater the angle Figure 4. β, then the output Cp will decrease. Cp would be maximized when β = 0. It means that the speed of the wind that blows all of them converted by wind turbines, without being reduced by the rotating blade pitch. This is the ideal condition of a wind turbine. Blade pitch goal is to reduce the wind speed is converted by the turbine in case of very strong wind speed suddenly causing a wind turbine spinning beyond its limits.

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Figure 4. Characteristic of wind turbine λ vs Cp β ranging 0-20 Figure 7. Characteristic of wind turbine Vwind averaging (■-β=0 ▲-β=5 □-β=10 ∆- β=15 ○- β=20)

Figure 8 and 9 showed that the simulation results of equation (2) with a wind speed variable V-wind that changes V-fox with a constant value of β. In the simulation, the wind speed was varied from 0 -12 with a variation of the value of β = 0, 5, 10 and 15. Figure 8, 9, 10 and 11 show that when beta = 0 and the maximum wind speed = 12 pm, the largest value obtained is Pm = 25513942.39, and at the lowest value of β = 15 Pm with a maximum wind speed = 12 obtained the value of Pm = 10168366.36 watt

Figure 5. Characteristic of wind turbine λ vs Cp (■-β=0 ▲-β=5 ∆- β=10 ○- β=15)

In order to obtain the mechanical power output, Pm was computed by the value of λ from 0 to 15 and the value of β from 0 to 20 as in Figure 4. Cp with a value of β 0, 5, 10, and 15 is shown separately in Figure 7.

Figure 6 and 7 showed that by using equation (2), and Cp values were entered in accordance with equation (3), then output the results obtained showed that the maximum Pm obtained when β = 0 and the lowest when β = 20. This means Figure 8. Characteristic Pm vs V_wind with β=0 that with maximum wind gusts, maximum Pm obtained with λ = 8, whereas when the wind speed decreases, the value of λ will grow along with increasing the value of β.

Figure 9. Characteristic Pm vs V_wind with β=5

Figure 11 showed that when the angle β was increased up to 15 degrees with a maximum wind speed, the smaller Pm obtained and the value of λ would also be decreased by Figure 6. Characteristic of wind turbine Vwind averaging β 0-20

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themselves from 15 to 12. The maximum power generated is equal to 10168366.36 Watt, with a value of λ = 8, although the angle β =0.

Figure 13. Characteristic 3D I2c vs V_wind with β=0-11.

Figure 10. Characteristic Pm vs V_wind with β=10

Figure 13. Characteristic 3D Pout vs V_wind with β=0-11

V. CONCLUSION

From the simulation result above, it can be concluded that tha Figure 11. Characteristic Pm vs V_wind with β=15 maximum mechanical power obtainde from a wind turbine is at a maximum wind speed at 12 m/s with a pitch angle β = 0 and value obtained for 25,513,942,39 watt.However, if the angle β Figure 12, 13 and 14 showed the simulation results of equation is increased to 11 degrees with the maximum wind speed, it (5) and (6) with a variable speed wind-wind V-fox that drops to 10168366.36 Watt. While the output current of an changed with the average value of β. In the simulation, the induction generator I2C when the maximum wind speed wind speed was varied from 0 -12 with a value of β = 0, the obtained with the value of λ = 8 and for all variants of the maximal flow I2C generated of wind speed 12 m/s. vlaue of β, the range of λ value ranged in number 8.

ACKNOWLEDGMENT The Authors convey gratitude to the Ministry of Culture and Education, Indonesia, that has provided scholarships through the program of BPPS and National Strategic Research funded in 2010.

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