EXCITATIONSYSTEMS

Presented by Satish Chand

142118222

Arpit Gupta

142118224

1

1:-Excitation current determines the strength of the magnetic field of the coil (along with speed of the rotor). This magnetic field then induces voltage at the generator terminals.

2:-If the generator is not connected to the load , there is no power flow, but voltage is even established with this magnetic field.

3:-The generator voltage will be strictly a function of rotor speed and excitation current .

4:- When load is connected, the generator voltage drops, with the increasing load.

5:-Voltage regulator however will increase excitation current to maintain constant generator voltage .

Introduction of synchronous generator excitation 2

http://control.com/thread/1360687812

FUNCTIONS OF EXCITATION SYSTEMS

Provide direct current to the synchronous generator field winding,

Perform control and protective functions essential to the satisfactory operation of the power system

The performance requirements of the excitation system are The performance requirements of the excitation system are determined bydetermined byA )Generator considerations:supply and adjust field current as the generator output varies within its continuous capability

respond to transient disturbances with field forcing consistent with the generator short term capabilities

rotor insulation failure due to high field voltage

rotor heating due to high field current

))

3

Lec-15 Excitation Systems-Part-2 nptel

contribute to effective control of system voltage and Flow of reactive power

Maintain the power systems stability with (PSS)

Elements of an Excitation System1.Exciter:

2.Regulator

3.Terminal voltage transducer and load compensator::

4.Power system stabilizer::

5.Limiters and protective circuits

4

5

Lec-15 Excitation Systems-Part-2 nptel

Classified into three broad categories based on the excitation power source:

1.DC excitation systems

2.AC excitation systems

3.Static excitation systems

4.Digital excitation systems

Type of excitation systems6

Lec-15 Excitation Systems-Part-2 nptel

DC excitation system with amplidyne voltage regulators

DC excitation systems

Lec-15 Excitation Systems-Part-2 nptel

7

AC Excitation SystemsAC Excitation Systems::

Field controlled alternator rectifier excitation system

8

Lec-15 Excitation Systems-Part-2 nptel

AC Excitation SystemsAC Excitation Systems

: Alternator supplied controlled-rectifier excitation system

9

Lec-15 Excitation Systems-Part-2 nptel

AC Excitation SystemsAC Excitation Systems

: Brushless excitation system

10

Lec-15 Excitation Systems-Part-2 nptel

Static Excitation Systems:

Potential-source controlled-rectifier excitation system

11

Lec-15 Excitation Systems-Part-2 nptel

GENERREX compound-controlled rectifier excitation system

Static Excitation Systems: 12

Lec-15 Excitation Systems-Part-2 nptel

www.

DECS-2100 system

Dual DECS-250

Single channel DECS-400

DIGITAL EXCITATION SYSTEMS

www.basler.com

13

DIGITAL AVR

The digital AVR is based on the analog AVR’S control functions and makes use of the advantages of digital equipment such as easier processing ,transmission and recording of information . Its hardware being compact the digital AVR has high reliability equal to that of the analog AVR.

FUNCTION: The digital AVR function is same as the analog AVR that is has AVR to

control generator voltage ,UEL(under excitation limit),OEL(over excitation limit) and PSS. as to the maintenance service functions, the digital AVR has such function as operation /fault status indication, self diagnostic generation of generator reference voltage setter step signals for verification of dynamic characteristics and recording of transient. It is possible to calculate bode diagram indicate transient responses and calculate rise times by feeding the recorded transient data to a personal computer via RS232C.

14

0-20A DECS-250N

 0-2,500Adc DECS-400

 0-10,000Adc DECS-2100

Benefits

The DECS family product line offers many integrated features and functions for regulation, limiting, protection, and data analysis to make your product selection easy.

DECS products are available for standard or custom solutions to be utilized on pan chassis or in cubicles as part of a complete system to

fit in your application.

EXCITATION CURRENT IN SPECIAL DECS MODALS 15

BE1-40Q Loss of Excitation Relay

Protection of loss of excitation

These relays provide protection for synchronous generators from extensive damage by detecting loss-of-field excitation.

BENEFIT Accurate protection provided by true var measurement.Minimized CT and PT costs as a result of low sensing burden.Reduced battery load with low burden power supply.Accurate, repeatable, and reliable operation.Simple HMI provides clear and intuitive settings for easy configuration.LED targets provide clear annunciation of status.Easily perform in-case system and device tests using test paddles.

www.basler.com/Products/Protective

15

Excitation System Application:Digital Exciter has Replaced of Brushless Exciter

Digital Exciter has Replaced of Shunt Exciters

Digital Exciters Replacement for ALTERREX

Digital Exciters have very high response that way systems is more stable

Have very less rotating part for controlling side that way less rotational loss

16

Reference

www.cigre.org.br/archives/pptCigre/02-2_Excitation

www.electricneutron.com/generator-2/types-of-excitation-system.com

www.nptel.ac.in/courses/108106026/chapter4

www.02abb.com/global/.../Brushless+Excitation

www2.emersonprocess.com

17

THANK YOU