PSG COLLEGE OF TECHNOLOGY ME – Power Electronics & Drives Dept. of EEE STATIC EXCITATION OF SYNCHRONOUS GENERATOR -BY R.RAMESH BABU(10MQ10) J.NETTIKANTAIHA(10MQ04) RAJESH KUMAR(10MQ38)
Aug 17, 2014
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
STATIC EXCITATION OF SYNCHRONOUS GENERATOR
-BYR.RAMESH BABU(10MQ10)
J.NETTIKANTAIHA(10MQ04)RAJESH KUMAR(10MQ38)
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEESynchronous Machines
Synchronous generators or alternators are used to convert mechanical power derived from steam, gas, or hydraulic-turbine to ac electric power
Synchronous generators are the primary source of electrical energy we consume today
Large ac power networks rely almost exclusively on synchronous generators
Synchronous motors are built in large units compare to induction motors (Induction motors are cheaper for smaller ratings) and used for constant speed industrial drives
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
Number of Poles:The number of poles on a synchronous generator
depends upon the speed of rotation and desired frequency
P=120*f/n f = frequency of the induced voltage (Hz)p = number of poles on the rotorn = speed of the rotor (rpm)
3
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
1.Dynamic excitation-by using auxiliary generators
a) Dc excitation systemb)Ac excitation systemc)brushless excitation
2.Static excitation system-by using power electronics devices
Types of excitation
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
DC exciter: A DC generator mounted on the main shaft may be of either the shunt-wound or the separately-excited type. The output current is fed to the rotor of the synchronous machine through slip-rings.
AC exciter: The AC exciter is mounted on the main shaft. Its field is fed from a pilot exciter, The AC exciter output voltage is rectified and fed to the field of the synchronous machine via slip-rings.
Brushless excitation system:An exciter of rotating-armature type is mounted on the main shaft. The AC output is converted to DC by means of a rotating rectifier. The direct current is fed directly to the field winding of the synchronous machine.
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEEExcitation system
From excitation generator
To main generator
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
primover
generator
gridPower electronic converter
Firing pulse generator
C
vact
vref
Step down
T/f
Firing angle
controller
verrά
Primover
contoller
Cfgrid
fact
Micro processor
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEEFullwave rectifier
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEEControlle stategy
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEESemi converter
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
PSG COLLEGE OF TECHNOLOGYME – Power Electronics & Drives
Dept. of EEE
Advantages: Can be operated at desired power factor - Source of
reactive power Constant speed (motor) / frequency (generator)
with load changes High efficiency - Brushless applications – reliable
operation