30-05-2012, 04:09 PM
Fundamentals and Advancements in
Generator Synchronizing Systems
[attachment=23581]
Abstract
Synchronizing a generator to the power system
must be done carefully to prevent damage to the machine and
disturbances to the power system. Traditionally, power plants
include a synchronizing panel to indicate what adjustments the
operator should make to the governor and exciter and when it is
acceptable for the operator to close the breaker. In many cases,
the process is automated using an automatic synchronizer with
manual control available as a backup.
INTRODUCTION
Synchronizing a generator to the power system must be
done carefully. The speed (frequency) and voltage of the
isolated generator must be closely matched, and the rotor
angle must be close to the instantaneous power system phase
angle prior to closing the generator breaker to connect the
isolated generator to the power system.
CONSEQUENCES OF FAULTY SYNCHRONIZATION
Potential Damage to Generator and Prime Mover
A synchronous generator is an electrical-mechanical
system. Three-phase voltages of the power system, when
applied to the stator windings of a generator, create a rotating
magnetic field that rotates at synchronous speed. Synchronous
speed is determined by the number of poles wound on the
stator. The rotor has a fixed magnetic field that creates a
rotating magnetic field when the rotor is turning and a field is
applied. When the stator is connected to the power system, the
rotor and stator are linked by the rotating magnetic field, and
the rotor must turn at synchronous speed.
SYSTEM DESIGN
Synchronizing systems for major generators must be
designed for high reliability. It is important that the system
provides accurate and safe synchronizing every time. There
should be no single points of failure that prevent placing a
generator into service. There should be no common-mode
failure mechanisms between control functions and supervisory
permissive functions that allow a faulty synchronization.
CONCLUSIONS
Synchronous generators must be connected to the power
system only when the slip (speed difference), voltage
difference, and angle difference are within acceptable
parameters. Faulty synchronizing can damage the electrical
and mechanical generating system, cause disturbances to the
power system, and cause the unit to trip offline.
Synchronizing systems include controls to adjust the
frequency and voltage of the incoming generator to the
running bus and instrumentation to allow operators to monitor
the critical synchronizing measurements to determine when to
close the breaker. The synchronizing process can be either
manual or automatic or some combination of both.
Generator Synchronizing Systems
[attachment=23581]
Abstract
Synchronizing a generator to the power system
must be done carefully to prevent damage to the machine and
disturbances to the power system. Traditionally, power plants
include a synchronizing panel to indicate what adjustments the
operator should make to the governor and exciter and when it is
acceptable for the operator to close the breaker. In many cases,
the process is automated using an automatic synchronizer with
manual control available as a backup.
INTRODUCTION
Synchronizing a generator to the power system must be
done carefully. The speed (frequency) and voltage of the
isolated generator must be closely matched, and the rotor
angle must be close to the instantaneous power system phase
angle prior to closing the generator breaker to connect the
isolated generator to the power system.
CONSEQUENCES OF FAULTY SYNCHRONIZATION
Potential Damage to Generator and Prime Mover
A synchronous generator is an electrical-mechanical
system. Three-phase voltages of the power system, when
applied to the stator windings of a generator, create a rotating
magnetic field that rotates at synchronous speed. Synchronous
speed is determined by the number of poles wound on the
stator. The rotor has a fixed magnetic field that creates a
rotating magnetic field when the rotor is turning and a field is
applied. When the stator is connected to the power system, the
rotor and stator are linked by the rotating magnetic field, and
the rotor must turn at synchronous speed.
SYSTEM DESIGN
Synchronizing systems for major generators must be
designed for high reliability. It is important that the system
provides accurate and safe synchronizing every time. There
should be no single points of failure that prevent placing a
generator into service. There should be no common-mode
failure mechanisms between control functions and supervisory
permissive functions that allow a faulty synchronization.
CONCLUSIONS
Synchronous generators must be connected to the power
system only when the slip (speed difference), voltage
difference, and angle difference are within acceptable
parameters. Faulty synchronizing can damage the electrical
and mechanical generating system, cause disturbances to the
power system, and cause the unit to trip offline.
Synchronizing systems include controls to adjust the
frequency and voltage of the incoming generator to the
running bus and instrumentation to allow operators to monitor
the critical synchronizing measurements to determine when to
close the breaker. The synchronizing process can be either
manual or automatic or some combination of both.