DETERMINAREA SOLENAIEI DE EXCITAIE A UNUI GENERATOR SINCRON PE CALE MATEMATIC
Buletinul AGIR nr. 4/2012 octombrie-decembrie 1
DETERMINADETERMINADETERMINADETERMINATION OF THE TION OF THE TION OF THE TION OF THE SOLENASOLENASOLENASOLENATION OFTION OFTION OFTION OF EXCITAEXCITAEXCITAEXCITATIONTIONTIONTION OF A OF A OF A OF A SYNCHRONOUS GENERATOSYNCHRONOUS GENERATOSYNCHRONOUS GENERATOSYNCHRONOUS GENERATORSRSRSRS, , , , BY THE MATHEMATICS BY THE MATHEMATICS BY THE MATHEMATICS BY THE MATHEMATICS
METHODMETHODMETHODMETHOD
PhD, Prof. Eng. Ec. Ion PIROI, Lecturer PhD Student Eng. Elisabeta SPUNEI
University Eftimie Murgu from Reia
Faculty of Electrical Engineering and Informatics
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1. INTRODUCTION
In the category of renewable energy sources,
established by CE, is the electricity produced in the
MHC with less than 10 MW power [3].
The majority hydroelectric power plants are equipped
with synchronous generators. They must meet users requirements for power, speed, operating mode
(autonomous or connected to the network), but not
every time these requirements can be met by large
manufacturing companies, which typically have lower
limited power. This is the reason why the authors of this
paper have proposed optimal designing of a
synchronous generator, designed to equip a small
hydro. In doing this we faced with problems related to
the excitation winding.
In the case of a synchronous generator designing,
especially low-power, solenaion excitation at rated load has a significant importance. At low power
generators there is a risk of insufficient space for
winding excitation is.
2. DETERMINATION OF THE EXCITATION AT RATED LOAD BY GRAPHICAL METHOD
The solenaion excitation is determined after the
construction of the partial characteristics of the
synchronous generator, represented in Figure 1.
Fig. 1. The characteristics of the synchronous generator.
The partial magnetic characteristics are:
- the operation in no load, ( )HUf= ;
- of the stator, ( )1djHUf = ;
- of the rotor, ( )HrUf= ; - of the flow of dispersion between the poles,
( )1djH
Uf = .
The operation in no load characteristc, ( )HUf= , represents at a different scale, the characteristic
)( Ee IfU = .
Buletinul AGIR nr. 4/2012 octombrie-decembrie_____________________________________________________________________________________
47
NATIONAL CONFERENCE OF ELECTRICAL DRIVES CNAE 2012
Buletinul AGIR nr. 4/2012 octombrie-decembrie 2
For the representation of the characteristics, all voltages
and magnetic flux values are transformed into relative
units (ur), and in Figures 1 and 2 these are symbolized
with tilde.
FIG. 2. The constructions necessary for the determination solenation excitation at rated load.
The excitation solenation at rated load is determined
by graphics constructions related the high
characteristics and presented in Fig. 1., construction
that are presented in Fig. 2.
3. DETERMINATION OF THE EXCITATION SOLENATION AT RATED LOAD BY MATHEMATIC METHOD
Because of the errors which can occur in raising
construction related graphics, the graphic method is not
always an accurate method of showing the correct value
of excitation solenation.
To eliminate this inconvenience, we developed a
computer program using Mathcad software, through
which, the excitation solenation at rated load can be
determined more quickly and accurately.
Next well present in short the methods used to determine the analytical excitation solenation at rated
load. The graphs used below, are conceived by us.
The magnetic air gap voltage, U'H, in relative units, is the relation between the magnetic air gap voltage, UH, at load operation and the magnetic voltage of the
synchronous generator, UH0, at no load operation, that is:
0
H
H
H
UU
U
= [u.r.] (1)
Depending on the magnetic air gap voltage, the
corresponding flow, ' , in relative units is determined (see Fig. 3).
Knowing the operating power factor of the generator,
imposed by the designing theme, follows the angle in degree and r in radians.
With this value of the angle r, and knowing the resistance of the Indus phase, r1 [u.r.], is calculated the large side U1a, of the triangle, which is the other side U1
respectively r1, in relative units, Fig. 4., with the relation:
( )2 21 1 1 1 12 cosa rU U r U r = + [u.r.] (2)
Fig.3. The variation of voltage flow depending on the the magnetic
air gap.
I
U1
r1U1a
x1
E1
O
Eq0
D
o
E1d
F
B
Fig.4. Explanations necessary of application
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