Post-graduate student N.V. Pronin

 

South Ural State University, Russia

 

The basic principles simulation of WPU-3 (Wind Power Unit)

 

 

In the present time, one of the most pressing problems of modernity is the problem of energy saving. The level of economic development is the main indicator of need for its speedy resolution.

The use of renewable energy with energy efficiency equipment can provide significant economic and ecological effects. Typically, in such systems a source of energy (heat or electricity) is a kind of device that converts wind, solar, water energy etc., necessary for us kind of energy.

Wind Power Unit -3 produced by "SRC-Vertical" (Miass, Russia) as a transmitter "the wind - electricity," uses the rotor WPU with blades and synchronous generation on a permanent magnet with axial gap (Fig. 1) [1].

Figure 1 –The basic elements of WPU

General characteristics of WPU are presented in Table 1. Considered source of electrical energy can be paired with a variety of potentially low-power and energy efficient consumers, such as infrared heating systems, pumps, and any appliances. No less interesting is the opportunity to work with both the overall network, as well as with other energy sources. In all these systems as a source of electrical energy can be used WPU-3. Therefore, a comprehensive study of this source, common to different systems, will enable its wide application in many fields.

 

Table 1 – General characteristics of WPU

Rated power of generator, kW

3

Rated wind speed, m/s

10,4

Starting wind speed, m/s

1

Range of wind speeds, m/s

4–45

The maximum wind speed, m/s

60

The range of speed, rev/min

60–200

Rated speed, rev/min

180

Number of blades, p

6

The diameter of the rotor (wheel), m

3,4

The height of the rotor, m

3,8

Swept area, m2

12,92

The height of mast, m

8­­–20

 

The mathematical model of WPU-3, which is presented in Figure 2 was constructed by using the software package MATLAB.

The model consists of the following components [2]:

Ramp – generate constantly increasing or decreasing signal. The desired growth rate of 0.1 m/s2 winds ranging from 1 m/s;

Saturation – limit range of signal. The specified speed limits 0 and13 m/s;

Math Function – perform mathematical function, provides a quadratic dependence of the output parameter of the input;

Gain – multiply input by constant, takes a value multiplier – 1.97676;

Permanent Magnet Synchronous Machine – model the dynamics of three-phase permanent magnet synchronous machine with sinusoidal or trapezoidal back electromotive force. The mode of operation is dictated by the sign of the mechanical torque (positive for motor mode, negative for generator mode).

Universal Bridge – three-phase rectifier diode;

Powergui – graphical user interface;

RLC Branch – consistent RLC circuit simulates the work of the rectifier smoothing filter;

Display – digital Display;

Voltage Measurement – voltmeter.

Figure 2 – Model wind turbine WPU-3

 

The general principle of the mathematical model is:

To block Permanent Magnet Synchronous Machine supplied a negative torque, which is determined by wind speed.

The torque applied to the generator turbines, depending on the wind velocity is equal to [3]:

                                                                                               (1)

where  - coefficient of torque, ;

 - density of air, ;

 - wind speed, ;

- swept area, ;

- radius of rotor WPU, .

The coefficient of torque  is determined at the maximum coefficient of using wind energy and rapidity(Fig.3), which is defined as [3]:

                                                                                     (2)

where,  - linear velocity of rotation, m/s;

 - wind speed, m/s.

Thus, the control system supports the rapidity , while providing maximum efficiency of use of wind energy , with coefficient of torque .

Determine the torque applied to the rotor generator:

.

Therefore, the torque applied to the rotor of the generator, is directly proportional to the square of wind speed.

With the help of blocks Ramp, Math Function, Gain describes the impact torque   on the generator.

Operation generator Permanent Magnet Synchronous Machine is described along the following lines of equations associated with the rotor [2]:

                                                             (3)

where  - q and d axis inductances;

 - resistance of the stator windings;

 - q and d axis currents;

 - q and d axis voltages;

 - angular velocity of the rotor;

 - amplitude of the flux induced by the permanent magnets of the rotor in the stator phases;

 - number of pole pairs;

 - electromagnetic torque;

 - combined inertia of rotor and load;

 - combined viscous friction of rotor and load;

 - rotor angular position;

 - shaft mechanical torque.

Figure 3 ­– The coefficient of wind energy  and coefficient of torque  from the rapidity

 

Block parameters are presented in Table 2.

The generator is a current source, alternating in phase, frequency and amplitude, which is difficult to use for the needs of the consumer. Therefore, the voltage applied to the three-phase uncontrolled rectifier bridge Universal Bridge. To smooth the ripple is the RC-filter with a time constant much larger than the oscillation period of the current in the coil.

 

Table 2- Parameters of the block Permanent Magnet Synchronous Machine

The form of the current

sinusoidal

Stator phase resistance Rs, Îhm

2,7

Stator inductances [ Ld Lq ], H

0,009

Flux linkage established by magnets, Wb

0,5

Inertia J, kgm2

1118,43

Friction factor F, Nms

0,85

Pole pairs

25

 

The measuring the output voltage with a voltmeter is V1, the frequency of the rotor with test port m block of Permanent Magnet Synchronous Machine.

Figure 4 shows the dependence of the rectified voltage from the rotor speed at idle mode , obtained by the simulation WPU-3 at package MATLAB.

 

Figure 4 – Characteristics of the idle mode WPU-3, resulting at MATLAB

 

Figure 5 shows the characteristics of idling mode, measured during testing of the prototype generator.

 

Figure 5 -Characteristics of the idle mode WPU-3, taken experimentally

 

Considered the generator produces a nominal power of 3 kW at nominal 180 rev/min. These values​​ must be achieved at a wind speed 10.4 m/s. As a result of calculations performed by the mathematical model presented in Figure 6 shows that when the wind velocity 10.43 m/s was recorded speed of 180 rev/min, load current 9.8 A, the rectified voltage at the load of 309.8 V, power 3036 watts, which confirms the close correspondence to the real parameters of the model calculation model.

 

Figure 6 –Model of WPU-3 at work on the load

 

Conclusion:

1)                We can talk about the behavior of the mathematical model under the real WPU-3;

2)                This model can be used in the simulation of wind turbine control systems, modeling of energy systems based on wind turbines.

3)                This material shows the operation of WPU-3 and is applicable in the study of this installation as visual aids.

 

References

1.                 Solomin, E.V. Production / E.V. Solomin // Web-site «SRC-Vertical». –htttp://www.src-vertical.com – Chelyabinsk: 2007. – 1 p.

2.                 Chernykh I.V. Simulation of electrical devices in MATLAB, SimPowerSystems and Simulink / I.V. Chernykh, 2008. – 288 p.

3.                 Kirpichnikova, I.M. The transformation of energy in the wind power plants / I.M. Kirpichnikova, A.C. Martyanov, E.V. Solomin // Alternative Energy and Ecology, 2010. – ¹1. – p. 93–97.