Download PARMENANT MAGNET SYNCHRONOUS GENERATOR

PARMENANT MAGNET
SYNCHRONOUS GENERATOR
BY
JA’FAR R.A. AZIM
Assem M.A. Al ighrair
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The modern history of permanent magnets stared about
1940 with the introduction of Alnico. Before this, the use of
permanent magnets was limited to a few applications such
as the compass and magneto whose very function
depended on the permanent magnetic properties. With the
introduction of Alnico, it became possible to replace
electromagnets with permanent magnets and the use of
magnets started to become widespread devices such as
motors, generators and loud-speakers.
History of Permanent Magnets
A permanent magnet synchronous generator is a generator where
the excitation field is provided by a permanent magnet instead of
a coil.
 Synchronous generators are the majority source of commercial
electrical energy. They are commonly used to convert the
mechanical power output of steam turbines, gas turbines,
reciprocating engines, hydro turbines and wind turbines into
electrical power for the grid. They are known as synchronous
generators because the speed of the rotor must always match the
supply frequency.
 In a permanent magnet generator, the magnetic field of the rotor
is produced by permanent magnets. Other types of generator use
electromagnets to produce a magnetic field in a rotor winding.
The direct current in the rotor field winding is fed through a slipring assembly or provided by a brushless exciter on the same
shaft
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Introduction
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They do not require an additional DC supply for the
excitation circuit.
The permanent magnet synchronous generators avoid the
use of slip rings, hence it is simpler and maintenance free.
Condensers are not required for maintaining the power
factor in synchronous generators, as it is required in
induction generators.
The generator is a brushless.
higher efficiency, as the copper losses in the rotor
disappear.
Advantages of PMSG

Large permanent magnets are costly.
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Uncontrolled air-gap flux density leads to over voltage and
poor electronic control reliability.
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A persistent magnetic field imposes safety issues during
assembly, field service or repair, such as physical injury,
electrocution, etc.
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High performance permanent magnets, themselves, have
structural and thermal issues.
Disadvantages of PMSG

Uncontrolled air-gap flux density leads to over voltage and
poor electronic control reliability.

A persistent magnetic field imposes safety issues during
assembly, field service or repair, such as physical injury,
electrocution, etc.

High performance permanent magnets, themselves, have
structural and thermal issues.
Disadvantages of PMSG
Structure of the Permanent
Magnet Machine
This model is similar to the conventional equivalent
circuit of the synchronous machine, except there is no
leakage inductance on the field.
EQUIVALENT CIRCUIT MODEL OF
THE PMSG
This model is similar to the conventional equivalent
circuit of the synchronous machine, except there is no
leakage inductance on the field.
EQUIVALENT CIRCUIT MODEL OF
THE PMSM
The demagnetization
curve of the magnet
that can be divided
into three regions by
three lines, called:
no load, rated-load
and excessive-load
lines.
We always try to not
enter the excessive
load region;
otherwise the
magnet is in danger
of being damaged.
Demagnetization curve
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Small-Scale Wind Power Generation System
Wind power is an energy source whose industrial application in the
world has grown at the fastest rate in the last 10-15 years.
Installed capacity of wind power plants is continuously growing at
a level of annual rate exceeding 30%. The European power
market has been the main driving force in development of wind
power industry for many years. In EU countries, a record
installation of more than 6 180 MW new wind power generators
was achieved in 2005. By the end of 2005, the capacity of wind
energy generation reached a level of more than 40 500 MW in
Europe and more than 59 300 MW worldwide. In Europe, the
current targets of using wind capacity are 75 000 MW by 2010,
180 000 MW by 2020, and 300 000 MW by 2030.
Applications

. A small-scale wind power turbine of the capacity 0.2-30
kW, with rotor diameters from 1 m up to 15 m may be
used as a flexible and vital alternative for local power
demand in isolated regions or locations.
Small-Scale Wind Power
Generation System

Permanent-magnet (PM) synchronous
generators are one of the best solutions
for small-scale wind power plants. Lowspeed multipole PM generators are
maintenance-free and may be used in
different climate conditions. It is possible
to combine PM wind generators for hybrid
technologies such as wind-diesel, windphotovoltaic etc.
Why PMSG

Traditionally wind turbine generators have used
gearboxes and pitch control to allow constant
high-speed generation under varying wind speed
conditions. In recent years contemporary power
electronics of high efficiency, high reliability and
decreasing cost offers the option to change the
power frequency out of the generator to match
the system frequency, which leads to the idea of
variable speed direct-drive generators.
Why PMSG

Traditionally wind turbine generators have used
gearboxes and pitch control to allow constant
high-speed generation under varying wind speed
conditions. In recent years contemporary power
electronics of high efficiency, high reliability and
decreasing cost offers the option to change the
power frequency out of the generator to match
the system frequency, which leads to the idea of
variable speed direct-drive generators.
Why PMSG

Compared to a conventional gearboxcoupled wind turbine generator, a directdrive generator has reduced overall size,
lower installation and maintenance cost.
Why PMSG