Asynchronous Machine with Wind Turbine IRFO Control

A. ALAZRAG, L. SBITA

University of Gab´

es, National engineering school of Gab´

es (ENIG),

Process laboratory, Energetic, Environment and Electrical system, TUNISIA

Energy has become a fundamental element because of our

different demands in many domestic and industrial terms.

This prompts us to always think about new techniques for

producing this energy. Since the dawn of humanity, the pro-

duction of energy has been based largely on fuels such as

as well as the reduction of nature reserves. So, we need to

look for other alternatives to fossil fuels to produce elec-

tricity from renewable sources that are non-polluting and

more economical by making good use of the elements of

nature such as water, sun and wind. This is the goal of our

These wind turbines have a nominal power between 5KW

machines in their different variants. Among all the renew-

able energies contributing to the production of electricity,

wind energy currently holds the star of renewable for re-

gions and countries with enormous wind potential. It is

study focuses on the Asynchronous Machine with indirect

orientation of the rotor flux which is the heart of a large part

other electromagnetic actuators. Dynamic management of

interconnected grid-connected wind farm storage systems

the efficiency of renewable energy sources. Stochasticity of wind speed and reliability of the main system components are

considered. The grid-side converter controls the DC bus voltage and the reactive power in order to accomplish the grid

codes. Speed control using flow directional control, indirect conventionally uses proportional integral (PI) type current

regulators, which achieve satisfactory objectives on torque and flow dynamics. The objective of this article is to present an

indirect vector control strategy with oriented rotor flux using current regulators of the proportional integral (PI) type,

applied to an asynchronous machine supplied by a voltage inverter, capable of supplying during restrictive stresses, more

satisfactory torque and flux responses. The obtained simulation results upon simulation tests of the global system are

developed under the MATLAB / Simulink environment and are satisfactory .

Keywords: Renewable Energy,Wind Turbine, Asynchronous machine (SCIG),Battery storage ,Indirect Rotor flux

orientation(IRFO),PI, electromagnetic torque, axis d,q.

control can be implemented using different approaches :

scalar or vector control, direct or indirect field orientation,

rotor or stator field orientation [12][13]. Scalar control [15]

is simple to implement, but easily unstable. A better per-

formance is obtained with direct vector control, requiring

sensed flux values to define and control the field orientation

references. This, however means that it is necessary to use

hall-effect sensors, which, inpractise, is problematic, and

expensive,[14][16]. The indirect field-orientation method is

modeling of the wind turbine connected to the grid as well

as a modeling in a two-phase reference frame (the adapted

model is based on the Park transformation) linked to the ro-

verters. of the double feed asynchronous machine. The Sec-

tion III,study of storage system. The Section V implements

the indirect vector control of the squirrel cage asynchronous

generator based on a PI (Proportional Integral) regulator,

Section IV the control ensures the decoupling of the d and q

important to point out that there are more elements, e.g. a

back full power converter.

generator, so the turbine is one of the most important el-

ements in wind turbine. In order to better understand the

process of wind energy conversion, descriptions of the ma-

be written as :

Where : S : Blade swept area (m2), ρ: Specific density of

Vv: wind speed (m/s), Cp(λ,β): Power coefficient, λ:

speed ratio, β: pitch angle With :

obtained from the following equation :

With :

a function of λfor different values of β. The maximum is

speed λopt =0 .

Where: J is the total inertia brought back to the generator

shaft, including the inertia of the turbine, the gearbox and

coupling is the sum of all the torques applied to the rotor:

chronous machine according to the axis q.

tor is expressed as a function of the axis sizes d, q:

It breaks down into three series of terms: *.Power dissipated

in Joule losses:

rd +i2

**. Power transmitted to the rotor in the form of a variation

of magnetic energy :

given by the expression:

Cem =P

Then the scalar expression of torque :

Cem =p.(φsd isq −φsqisd )(II.22)

neous torque by using the stator flux expressions:

Cem =p.M

And :

Active and reactive power, provided by the grid-side con-

verter, can be expressed as:

ampere-hours (Ah) that can be extracted from the battery,

for given discharge conditions.

• The state of charge “SOC” (State Of Charge): This is

capacity Qn, is :

If SOC=1 the battery is totally charged and if SOC=0 the

battery is totally discharged.

(En). The charge and discharge equations are given as fol-

lows [7]:

*Discharge :

*Charge :

charge and discharge the battery.

Figure 9: Circuit of the DC–DC bidirectional converter

the battery storage. Figure shows the circuit of the boost

The buck mode is applied for the charging process of the

the lower voltage side . The averaged large signal inductor

given by the system of equations below

The three-phase voltage inverter allows the exchange of en-

tive load [2].

switches of three legs in inverter controlling the phase volt-

vectors [0, 0, 0] through [1, 1, 1].

Table 1: the phase-to-phase and phase to phase voltages of

the inverter according to the states of the switches

given by the following equations:

(IV.3)

Then :

VB=Vdc

(IV.7)

Where Te is the sampling period.

nitude of the rotor flux but simply its position calculated

indirect vector control with oriented rotor flux of an asyn-

chronous machine.

solve the following system of equations:

the two regulators are identical. The current regulation loop

respectively Isd and Isq can be represented by the figure :

With :

Isd (s)

The characteristic closed loop equation looks like this:

ured in order to control the DC bus voltage and the reactive

the grid side. The DC bus voltage reference and the grid

figure 16 depicts the block diagram of grid side control.

Figure 16: Block diagram of grid side converter control

The PLL is used to provide a unity power factor operation

PLL structure are calculated in such a way that we can set

directly the settling time and the damping factor of this PLL

structure. The principle of the PLL is depicted in figure 18.

equal to zero, which allows the decoupling of the active and

changed between the network and the DC bus is given by

terised by :

Nominal power : Pn=2500000 W;

Nominal voltage : Vn=690V;

Table 2 : Characteristic of asynchronous machine .

uated using the software MATLAB / Simulink.

This parameter depends on the blade number of the wind

that varies with the wind speed.

Figure 19: Wind speed evolution

have a Cpbetween 0.35 and 0.45. Cpis specific to each