Barzam A.B. Automation in Electrical Power Systems (Системная автоматика)

CEAPTER ONE

.A'UTOMATIC

CONIROL

OF S}"I{CHRONOUS

GENERATON

EXCITATION

Sometimes

tbe voltage relay is corDected

to

a separate

voltage

tr8lslorEer

: I-3,

Excitation

Compoundiaq

with

Cuqulative

which

is

LqBd only

by

the etcitation iegul4ting device apd it has

po

fuses and

i

Connertinn

.'t tr'.lectropq-gn€tic

Vellag€

circuit

breakers iD

the

E*suring

circuit.s. The circuits oJ tbe exoitation lorcing

Corlector

devices

ean

be also contro]]ed

by

blocking blown

fuses

in a

way

similar to the

remote-control

protection

of

transmission

lines.

To

improve

the

efficienc-v oi

the

excitation

forcing

devices, the

voitage

relays

are connected

to a forward

sequence

voltage filter

(Fig.

1-6a).

Often

this

II

vl

llf

-l

Ir

I

rsl

43

.t!

Generator

compounding,

i.e.,

changing

the

current

floq,in

the fieid

coil

as dictated

b-r' the

current,

florn' in

the statoi

with

a

view

to

improving

tbe

g.or-

rator

external

characteristic

is

accomplished_

b-v rectifying

and

add"ing tJ

the

fieid

current

(Fig.

1-7)

a

current.

proportionai

to

the

statoi

curent.

u8

uC

h)

ac

I

_J

k)

Fig. t-6. Ercitation

forcing with

the

aid

of relay

sequence

iilter

ia)

excitation

forcing circuit:

(b)

internal

connections

onnliaa*inn af lrralrwar^-.cdrrpnnp vn)trtp

'tn

lilt.cr' /rt)

oP'"veu'v"

"*'- "-ifi;a-i'e-ffince

voiiiee'to

filter

is

of

the

resistance-capacilance

t-rrpe

(Fig.

also

potential diagrams of

the fiiter,

when

it is

connected through forward-

of

filter;

(c)

diagram

sholving

dirqrem shn*'inr annlieation nf

til

ter

1-6b). Shou'n in

the

Figure

are

at

the

forward

and backward-

sa tis-

(1-s)

of the

-->

Iph

conl

/. I

'

tDj

sequence

voltages.

It is clear

from the

diagram

that if the impedance of the

filter

arms

fies

tle

condition

R1: rs1: frcz:

R2:

+

,

+

tlre filter output

voltage at the

positirre

phase

sequence is 150

per

cent

rated

interphase

voltage.

The

excitation

forcing device

must

be furnished with switches

to

allor*'

attending

personnei

to remove

the

device

from

operation. Because of

the simple

conslruction

of

the

relay-type

excitation

forcing

system, its application is

liitel--v

to be usefui for all

senerators

and synchronous capacitors.

whaLever

the

automatic

excitation regulation devices

enployed

by these

machines.

I

tnmP

/ \

ta)

Fig. 1-7.

Compounding

device

principle

(o)

full current

compoundingl

(b)

pbaee

compounding

With

combined

use

of

a-compounding

device and

an eJectronagnetic

voltage

corrector, two

systems

fo-r

excitation

compounding

of geierators

miy

he

employed.-_These

are

't'ull

current

contpoundtng

and,-phast

io*pounding.

I;

the

case

of

ful]

current

compounding

the

actions

proportional

to the

stator

cur-

rent

and the generator

voltage-fed

from

the

iuitrument

current

aud

voitage

transformers

are

summed

up

.after

rectification

of

the

currents.

In the

caEe

of

phase

copPou-nding-this

is-done

before rectification

of

the

currents,

i.e.,

on

the

a.c.

side, which

allou's

the. effect

of the

phase

angle

between

the

stator

current

and the voltage

to

be taken

into

account.

n

In,

x

t,

B

.r','h\,>-

\

oo7

'i^,/

r\z-

V

,rrl

AT

L-i

s

I

rt

.cntnl,

[-:

,-T4

iu,

I

L-.

Qu

*i

't 't

't

I -

=

t_

+

!

t

-L

'.pn.

cpmp

CHAPTER

ONE

..

As_compared to

the

fuli

current

compounding

device,

the

phase

compoun-

d-ing

tievice

:laintains

the

generator

terminal

voltage

more preciseiy.'More

thal that, the voltage

corre-ctor

intended

for

holding

the

specified

-r,oltage

ievel uses

significanti,v

smalier

power.

\lTiiolrr rrcorll {^. or.aifo*i^- -^-"1^+.:^* ^-a ^--^rr^a:-- ---a--rr-- -

.,r

ruuvr.Y

spvq

rvr e^v^!curuu

reEul.clUIul!

alrt; V^(rl[.aLfU!

GOIlL.fOllgfS'WIln

COnt-

rolled

phase

compounding.

Let ul

consider the

action

of this

deviee

in

more

detail.

With no

compounding

and with

the

resistance

of

the

stator v-indings

negiected.

the

voltage

across

the generator

terminals

in

con-

formitl'

with

Fig.

7-2a

tt(*'ilh f

=0)

I,(nith 9=0)

Us:Es-jrcle

(1-10)

If the emf

and

the vaiue

of. z

r

are

con-

stant.

the external

characteristic

oI the

Eene-

rator

is

determined

by the

straight

line

I in

Fig.

{-8.

The voltage

decreaies

u,itb

an

increase

in the

stator

current.

To

keen

the

Fig.

1-9. Ciiaracteristics

oI

compounded

generator

(o)

geDerato!

emf Es

versus

Ioad angie

I

when

Uo

is

constant;

(b)

external

characterjstrcs

of

generator

coropbunded by

ful}

current.rvith..diflerent

cos

g;

point

a stands

for

tbe

eom-

pounding

thresboid

It(vith

f

=

90")

k)

f

-1

(b)

Fig.

1-8.

External

characteristics

of

generator

must be

able

ro

increase

tbe.JTf*:

constant

(line

2)'

the

contro]

db'ice

A,E:

jccl

e

(t-11)

+

I

varvins thp trensfnrirre ti nn i" +l^ ;i ;i." l;;;1;J;;*---

-.:,;;-;::";::-:;:::6^':

As

shown

in

Fig. 1-10

the

current

transformers

are

counected

to

phases

I

and

C

and

thg

e.r:rrent

in

the

sgries

s'indinc, ?

pmrqlq

{ha rva++n. iiffo*o--.-,

berween

rhe

seconaary

curr."tr

riiLr;;#E..

rll-#rrit

i,

iilT ##'dr,r?";

Fig.

{-1.0.

AEC

circuit

with

coutrolled phase

compounding

Lt

u

I

'I

I

I,9AT

I

'+,

tl

T'

,_j

Il

I

t

I

tFP **1 il r;

aa" L.

tt

-t

T-

\r.clArr,E;ft

uJ\-!.i

of traasformer

TM

musl have

such

a

phase

current

of the generator

and

the

current

in.the

?

windins

leads

the

The

above-mentioned.requirement

is

mr

to

tire

voltage

U",

deveioped

across

instrument

transformer

p'ith

delta-star

The

reactance

coil

(ftC)

makr.

tn.

.

dent

on

the

voltage

imposed.

The

react

AU?OI'ATIC

CON?AOL

OF

SYNCERO^.OUS

GENERA"OR

EXCITATION

+t

regulator

must

maintaiu.

z.

{

4

3_

ao,

un

Fig.

1-12.

Characterjstic

of

masnetic

amplifier

in

controlleci phase'-"om-

pounding

device

regulation

at

no-Ioad

and

smallload

of the

winding

I

is sm.all.

The

autotrar

supply

voltage

so that

the

impedance

portionaiity

between

the

current

in

t]:

such

a

voltage

increase

materiallv

decre

capacitor

C

u-sed

to

decrease

the

load

:

For

biasing

the transformer

fiy'.

use

to the.output

of

the

magnetic

ampiifier

the

voltage

transformer.

-The

intermediate

amplifier

is

controlled

from

a three-

pha:g

measuring

element

a1d

together

n'irh

it

makes

"p

iu*.

;;il;"

correcror.

The

noeasuring

element

/1

has two

windings.

Tirerfl.

"

prt*?r,

winding

used

as

a non-linear

eiement

which

feeds

plwefto

one of

irt.

*igr"iic

amplifier

winding,s (winding

tr)

th"ough

the

ooo-lio*rr

element

r."tit-i...

NER

and

a secondary-

winding

feeding

{he

tWn winding

^L

(linear

element)

r.ia thp renri_

fiers.LE.H.

The

1-rlltill

effecr

produced.lv

Cl,

*"lorti.

it";;;'"-;;;;.;;;

currents

.It

and

-I,

in the

magnetic

amplifi6r

is

dete]rminea

ly-

in*

currenl

dif-

O

and

rectifiers

Sn).

i.e..

*itn

ifr.

;;:;;:?

Fig..1_1,3.

Outputcunenrof

excjrarjon

flowing

in

the

excit,ation

winding

of

the

i"E"r"t",

*ilt'.;;;;;iird

phase

conr-

exciter'

The

other,

u'inding

^9C

is

}ed

with

p-oundirg

"*r".

[*.."to,

voliage

the

stator

rectified

".rrr"o..,T

;i^". t,^r.,^

controiled

bv tho

";"t";:

-

""""

YqruE

rs

50oz;

generator-toaii

witn'*=r-ip'ti,5!i't6

i

the

l-

?Gil#J#i.?dT[

a-"t"sy,r

li

i

Iorl's

ormer

to

be

reduceri

about

2

times.

F.

at

the

output

of

tlie

magnetic

an:pji_

correctol.

the

excitation

eircuit either

by

connec_

r

the

manner

shown

in

Fig.

f_10

or to

rse

is

made

of

_a

separate

eiciting

u,ind_

m

the

AEC

device.

device

is

dependent

on

the

frequencv.

rakes

the voliage-var_]r

b-v

1.0

to'f.5

pir

tut

650

W.

At-the

2O_[f

capacirance

num

feed

current

from

the

thiee_phase

thirdphase.A*he;+"ilfr

";;H;:;F",il"":l;:J#:ff

Sii,'.;l;$f,ii"n:

formers

is

abour

200

volts-'iutr

*it-g"

d;.;;;.;r"*tro

decreasing

ourput

po$Ier

Fig.

1-11.

Characterisrjc

of

AEC

mea-

suring

element

ir I

I'n.e i

I!

Set/

-

holatng

onc'

manu1l

resel

tircat !s

Ciosure

c!

conloctcr

$C

thPo

and

generolor

s*'ilcn

lurning o11

fDC

n^.^;nh nl rnnlnrlnr S( vhen

lhe

voltope

ii"ii'i'ti

ttiii,t

Circuil

of lhe

rclenoid

closing

SC

tlosure

o!

circuil..2

whcn

eircuil

.

bred*e'-

CB

it--[tt:t

"t

lrfun

lhe

roltage

loi!J-

lo circuits

f-4

ot

llA'l

and

l'lA-2

Err- t -t t A F(1 snrt cvcir'or.ion forcinp devices,

twe

S[IA-3258

for high-frequency

r

rE' r-

r='

""

""iii*tifr

o"

g"o"ttiors,

"series

T B

B-i

50

and

rB

B-300

_(a)

scbematic

diagram:

(b)

variant

of automatic

Ewitching

for starting

period

(6)

-.'a

AuToMATre

eoNTRor,

oF

s:nsc4oNoTts

GENE.EATOR

ExciTATiori

4g

of the

device.

The

output power

capacity

of the

device

is sufficient

to ensure

the

regulation

of

lLt^:qlt_qge

of the g-eneralors

whose

exciters

have

an

excitation

power

not

above

1,000

kW

at

the rafed

load

of the generators.

When

use

is

nade

of

greater

excitatior

powers,

two

sets

of.

EAC

d&'ices

must

be emploi"a,-""

exampl-e

being

h-vdraulic^generators

eguipped

n'ith

exciiers

whose

fi;id

t;*;;

ranges

from

1,000

to

2,000

kW.

One

"olage

corrector

which

is

ioonected

to

the

series-connected

control

coils

of two

TM

transformers

may

be usea

in this

e"eni.

1-4.

Exeitation

Controllers

of

Generators,

Series TV\/.

with

a

High-Fregueney

Exeitation

Systcm

The

TV\i series

generators

u'ith

a

high-frequency

excitation

systern

are

furnished

urith

excitation

control

devices,

type-EPA-B?tp

(?qA-8258)

(Fig.

1_ia)ti-al.

This

device

includes

an

automatic

excitation

controller

(aPC).

of

tbe

propbitio"nai

iyie, q"irf-".iion

excitarion

forcing

device

(QFD)

and

a

forcins

limiter

unii

tFtil_-'

forcing

device

(QFD.)

and

a

forcing

limiter

unii

titil.

The rotor

rrindins ,]?o is srrnnlied ntit.h a ro.rifio.l ^,',,

The rotor

uindins

fio

is

sunolied

Tvith

a rectified

cur"ent

frop the

high-freguency

gene-

rator

flFG

baving

three

fleld

(ercitation)

windinss:- n

pi-ir,iin;,

fi.Id liif

?i%i're4ed

in

series

The EFC-?

coil

is.connected

to

the

MA-2

amplifier

of the

AEC

device.

The fieid

buiit

up bl,

the

EFCjl

ioil

exceeds

tbe vaiue

needed

for

normal

dperation

of the

EFi

generator,

the

excessive

amount

of

field beins

comDen_

sated

for

by the

efiect

of

current

flowing

in ihe

niC-S

coil.

- .Figure

1-15

shos'-q the

output

current

characteristics

I

of the.magnet,ic

amplifiers

employed

by the

automaric

An

;;:.ii:'ii; o'f\'iftn;iii ,q:::\-:*il:.;-i:*r::, i:l:ilq

Fic.

i-15

characterisricsor ARC

oI

lne

non-llnear element.

T'he use of

direct

feedback

compensates

for

the

magnetizat"ion

effect

of the

magnetic

amplifier

MA-z, caused

by the

currenf

trom the-cooi"otll."o,."ifri;;

I

-2076

-r-

I

AUTOMATIC

CON?ROL

OF

SYNCERONOUS

GENERATOR

EXCITATION

51

utlAHltl-t{. t t\tt

in

tte

z'rc-s

Coil,

ii""t"n

iiJi,

mplifier

Nn:Z),

a

cunen"t

app_

and

in

the

EFC_]

coil.

After

a

opening

of the

linear

element

c

rator

is

Decessary

to

limit

the

vo

the

starting

conditions

to

0.5

of

th

The

SrIA-3258

regurator

assembrl,

incorporates

an

excita-

tion

rorcing

limfter

and

deexcitation

rinits.

r[.

.r"it"iloi

ror"_

ing

limitei

employs

magnetic

element.

g,irh

fhp vrr tnat-

current

flou'in

tbese

windings

is

c<-rnrr"ii"E

t" il';"';;'"T;:",'"F;: .i!j^!',! -!

{f

ie'

1-14).

The

lo

flt'U

exctler

-----"1

l+

LIP

Fig.

1-16.

Excitation

forcing

limiter

of

SIIA-3258

device

of

the fVP

generator.

.'

'_ ';;""\;?

Ji..-i;y'q

.9{f":!r_l!:

t"l:l_q:-"_d),,y:"{*g:^9l,tl._"T.""s-:",T"-"111}j:::

MA-l

ale

supplle0

lrom

lne trrgl]-IrequerlcJ'B'elrc.raluI

If f trr

wIU.t_t_Yr-uo6',rr--'"

-'"

;i f;;.iil

t.'rffia""r

a

positivEfeeddack

efiEct,

i.e.,

to

provide

ad-ditional.gain.

When

start-

i;b,

;i';""*;d;;;;sc;fi;;d'

on*"-ih.

MA4

po*.i

wiirdings

to be

supplied

from

the high-

l-5.

Overaction

Excitation

Controllers

The

quick

action

of the

controllers

of

the

type

under

consideration

and

the

accuracy

with

which

they

maintain

the

controiied

variable

are

attainable

not

oniy

by

accomFlishing

the

control-pto"*-i"-r"-prir"*-ilh

ih*

ouri"tious

of

the

value

un{-er

c6ntrol,

but

alio

*iin

tit.

?t.

and

acceleration

of

these

variations (accordine

to

the first,

and S€ennd dori,,ori-,^.r

rnr-,-

:=---.

gualitv

is possible

i'irh

"o

"n"it"ntr

-.r"it"i;;;'r-;'r"r#.;ffr':ff;::

;"f,?fl1

speed volrage

rise

across

rhe

roror

windinl

i.r*ir.ri

or-tne-|eolii.o..

4*

CEAPTE.R ONE

AIITOMATIC

CONT&OL

OF

SYNCENONOUS

GENERATOR

EXCITATION

To

improve

the

stability

of

generators

operating

in

parallel

as

foilows

from

(1-3)

and

Fi.g.

1-2,

it

would be

.good

practice

to

accomplish

tle

control

process

by

ihe angla

6. However,

to take measurements

of

the

-ang-Ie

6 between

the eml

vector

of the

generator and

the

voltage

vector

of

the

busbars

of the receiving

s-ystem

}ocated

at

a

great

distance, often calls for

the use of

telemetering

means.

The

use

of remote

control

equipment

for the control

purposes

complisates

the

device

and

lowers.operation

reliability.

With

networks

of

simple

configuration

which use,

for

instance,

a

generator-

transforrner-transmission

line-receiving

system

set,

the angle

6 can

be determi-

ned

with the

aid of

the

so-called

phantom

diagrams

(see

Chapter

4)

which simu-

Iate the

impedance

from

the

point

of

the

geaerator emf

application

to the

P.oint

of

voltage measurement,

and

to the busbars

of

the

power roceiving

system-(this

impedance

opposes

the stator culrent,

tbe

corresponding

voltage drops

being

veCtor added

to

the stator

termiual

voltage).

However,

such

a measuring

technigue

has

not found

wide

application.

Moit

often

used

are overaction

excitation

controllers

which

perform the

contro]

fuuction

by

eiectrical

variables

dependent

upon the angle

6,

namely

by

the

value of ourrent

in

the transmission

line and

the voltage

at

the

line

point

ttnder measurement.

To

make

the control

process

more

rapid

and

stabie,

the

first

and

the second

derivatives

of

the

above-mentioned

guantities

are

intro-

duced

into

the

controi

equation,

or

the

value

of frequency

variation

and

the

,lerlvative of

this

variation, as

the

frequency

variation is

propor-tionai

to

the

first derivative

of

the

6

angle

variation,

whiie-the

ireguency

variation derilA-

tive

is

in

proportion

to its

second

deriva*uive.

The matLematical

expression

defining

the control

equation may

be

written

as

,d-n.'dnz

lJ

-

li6fi-r

lit

.--':-

i

ti.,t

--=-

'dt

'diL

ristics

are

plotted

for

a

generator

whose

ving

svstem

over

a long

transmission

line.

The

stabie

zone

of control

varies

s'ith

-,he

value

of the

init,ial

angie

of

transmission

(60).

The

control

coeffici-

enis

are

seiected

so t,hat

the

controi

proces-c

is

stable

for

any

value

of

angle

6-0.

When

changing

over

to

control

by

tbe

current

and

its

derivatives

or bv

the

voltage

and its

derivatives,

th;

Fargin

of the

controi

stability

varies;

however,

the

character

of the

nrocess

and

thus

the

possibility

of

chooslng the

optimum li,

and k,

coef.f.icients

remain

the

same (Fig.

1-19).

Overaction

controllers

can be em-

plo-ved

-both

by

hydroelectric

genera-

tors

and

turbogenerators.

In

the

majo-

rity

of

cases

the

controllers

are

used

in

conjunction

rr"ith

a

gr

tube (tl-r'rirl"tl

excitation

termining

control

c'oefficients

compared

with

proporrion

fiiilf"lll:.",ni'#:i"1iH"t:

plc;red

bi.

the

n:acirines

wj

sbaded)

the

USe

Of

Overa.tiOn

AE(

re

Dean.

coordinatF

ot

points

lo-

nes

furnished

with

"-!rr-,

n tire

sta-ble operation

re5:ion

tube

excitation

s)'stern

ma1.' raise

the-steady-stat,e

stability iimits

by

10

to

30

per

cen'r,

and

the

trinsient

stability

iimits,

b],

6

"to

l0

per

cerrt.

output

power

is transmitted

to

a

recei-

rrrhere P

rln - [Zn

z.*and6.

hunting.

The-optimum

coeffioients

are

dependegt

upon

the_power

system configura-

tion and

also

upon

the

direction

of and

relationships

between

.the-

power

flows

over

the

transmission

]ines connecting

the

powcr station,

at

which the

genera-

tor excitation

control

is

performed, to

the other

units of

the

system.

Figure

{-tB

shows

the

characteristics

which

determine

the

margin

of stable

opr."iioo

of

a controller

accomplishjng

tbe controi

operatio_n

by

the angle 6 and

its

first and

the

secoDd

derivatives

for

various

k,

and ft,

values.

These

characte-

(1-12)

:

Dararnoter of operation

b-v

which the

control

is

performed

:

absoiuie

vaiues of

the coniroi

parau.ete-r

varia-uion

anri

'uhe

first and

second

derivatives

of

this

variati.on, respectively

(")

Fig'

1-19.

Typicai

changes

in

s_table

control

regions

with

different

control

.

cobfficients

/r,

and A,

-

(a)

power

tranrmissionrcircuit;-l?)

J""""l3tT'r"L"l"t'rxo#.gl*l?t'

'r

-

ansle

6

control;

One

model of

the

overaction

controllers

developed

by the

AII-Union

Electri-

cal

Engineering

,inst,ituteit-5i

proviries

resultanl

effects

on

the

excitation

system

by the

following

factors:

I

AuToIvrATrc

coNTRoL

oF

syNcERoNous

ctNERAToR

ExcrrATroli

55

il0v

4S0Hz

ttOV,450Hz

GCSII

-W

J{

CEIAPTER

ONE

(a)

By

the voltage departure

A

U

from the

rating,

v'ith

the

coefficient

a ?A

excit. unit

fi6U:

Cr-;5i15;if

the voltage

derivative

(by

the

voltage

variation

rate)

da

a

dI

dt

(b)

BV

the

value

of

with the

coefficient

(c)

By

the

variation

I

7, n

excit. unit

rig,:

g

trg ,

Tit.

uoitl,

oJ the

value

of

stator

current with

the

coefficient

kr:o

to,

excit'

unit

cur.

unit

(d)

BV

the

value

of

stator

current

derivative

(by

the

current variation

rate)

with the

coefficient

k't,:o

to

8.r

l-l!i',,],lll

cur. unrt/s

(e)

B-v the

vaiue

of

the second

stator

current,

derisative

(b1'

the

current

variation

rate acceleration)

ffi

w'Lth

the

coefficient

k'i,:0

to

1"rr;

"'!ii'il:=YI,t

-"--

cur.

unitlss

(f)

By

tlie

value

of the

rotor current derivative

(bv

the

current

variation

speed)

u'ith the

coefficient

ki,

,ot:

0

to

Z.

z

--era!-lntl-

rot..

cur. unjt.is

The

nominal

values

of current

and

voltage

are assumed as excitation

urril.-s.

The optimum

gain

factors

for various

channtls are

determined for

eacir

device

b5r

means

of

precalculation

and

actual tests in the

po\r,er

s_vstems.

In order

to

make

the

external links

of

the

regulator

more simple. the effect

produoed by tiie freguency

and its derivative

may be used instead

of that

pro-

duced by

the

derivative of

line

current. Experiments

on mathematical

models

have shown,

however,

that system

hunting ma]'

occur,

when power

close

in

vaiue to

the

steadv-state

stability limit

is transmitted. In addition,

anaJyses

of a series

of

emergency

situatious

have

shou'n that undesirable

falls

in the

busbar

voltage

of the station

occurred due to the

use of

frequenc-v

channel,

when

an

active

power

shortage

arose at that

portion

of the

power

s_vstem

u'here

[he station furnished v'ith

a

AER

was located.

Because of

this

the frequency

controi channel

is

mostly

used

for control

of synchronous capacitors.

The overaction controller

includes voltage

unit

7U, current

compounding

unit

CCU

rtith

an

intervening

current

transformer

ICT and

an

operational

unit OU

(Fig.

1-20).

Tbe

voltage

unit

includes

a

control motor CAI,

receiver

synciuo RB,

different,ial

synchro

DB, mechanical differential

MD, rectifier

luoffi,l

i

"

l'.il I

--l

|

,;o*

f

r-

I

trtttn/

iDct\

iL

t

Tcr

lr

I

t,

I

l

IL

I

t"*t,

l

rnrr F1----.l-_

- -:-.l

ll I I

I

l'--rll

rrrJ

ll I I

|atttt

i

T

L-----J

, ,,

(or'circ

I I I | |

j

.t.r.ttov

i-{il{-i il

I i

,

,,

._f,Fl

ll

I Wrqrhl4,il-{=-+--.1 rr

i

soHzt_r4souzlll

>=-

Arr.fr

I I

rl

lr

lL

vi

Ftg.

I-24,

Circuit

of overaction

AEC.

Symbol

F447

stands for

a

device used

to

translorm

380

V

50

Hz

power

into

110

V 450

Hz

power

I

:

I

CHAPTER

ONE

tion unit

AIEa

which is

fed

from a

d.c.

transformer

(DCT),

and

the feedback

unir FB-U*

which

is acted upon,

depending

on

the

value

of the exciter

voltage

U

rot.

The output

eircuits

of the

operational unit

are

connected

to the u'indings

oi t,he

summing

ryagnetic

amplifiel

,4.I

s'hich

serves

as the first

amplifier

s"uage.

The

second

amplifierstage is implemented

by the

magnetic

amplifiers

AII-W

^-l I f T fi mL^ -^*-^- *-:-l:-- ^--*^-r ^! rL^ t rf tr: - -- t.!. . .r

tJuu

Att-r. rus

Fowsl'

wr.u(rrug

gurrEJr.L

ur LIIe

AtI-

yl'

arrt.pluler

acIS

upon

tne

semiconductor

grid

control

svstem of the working

group

valves

GCSII-I|i,

while

the

current of

the power

winding

of the

AII-F amplifier

influences

the

AU?OMATIC

CONTROL

OF

SYNCERONOUS

GENERA"OR

EECI"ATIOIIi

semiconductor

grid

control

svstem

of

tbe

forc-

ing

group

valves

GCSII-F.

The action is eff-

ected

through

output filters

F

which

reduce

the

a.c. component

of the

outpur

voltage

to

150

m\r. Figure 1-21

shows

the

diagram

o1

the

fil ter.

Marked

IE

on

tbe structural

diagram

of

the

reguiator

(Fie.

{-20)

is

sas-discharge tube

minate tbe

obiectionable effect

of this signal.

1-6.

Conclusions

3

Proportional

excitation

controllers which

respond

to

variations

of the

absolute

values

of the

controlled variable

are built

mainly in the,forn

of

com-

pounding

devic,es

with

an electromagnetic

voltage

corrector.

4. Overaction

controllers

react

noi;

only

to variations

in the

absoiute

values

of

the

variables

being

controlled,

but to its derivatives

as well.

This adds to

the

sp-eed.of

response

and

accurac-v_of

the

controi

(regulation)

process.

The

most

effective

control

i:

lv the

angle

6 and

its

derivativel.

l"

pti"[i..

the

controliers

accomplish

control

to

values

dependent

generator

staior

or

in

the

line, to

the

first

and the

second

derivative-q

oi

ing-of

their

windings,

must

be

provided

and

duration

of forcing,

and

also

with

age

to'

the

exciter

and the

excitation

uctor

elements,

because

of

intolerabie

rg

dut5.

1-7.

Review

Questions

1'

wh-v

does,

the

t::?ll:i

operation

stabilitl,

of

slnchronous

senerators

increase,

n,hen

use

is

made

of

AEC

der.ipes?

o.ti"2uJll,liil

t:r*:;#Ir"J'i"J'reiav

forcing,

,n'he,

I compouDding

tievice s'ith

an

erecnomag-

3' Hthat

is tbe

difference

between

tlre

proportional

tl,pe

excitation

controljers

and

the

overaction

controllers?

iog

f"

J:rtT

is the

purpo'se

of

relay

forcing

wben

a controller

r.'ith

controlled

phase

compound-

5'

what

are

the

operating

p.rinciples

of the

}inear

and

norr-linear

elements

emplol,ed

in

tbe

peasuring

compoi-ents

oi'tir",ioir";;

;rgui;;ilo'"devices?

6'

what

ls

tlLe

iottu"o""-oi

Jy-n"Lrooous

machine

excitation

controllers

orr rrrp vnrrqoo

iesi.oring,;-ro::"=.,fFl

i-s6isrjng

a

;h;;t*i.;It"

i""ftf^

;!',!g6c

machine

excitation

controllers

on

the

sbort_

overactjon

controllers?,

Erplain

the purpose

rs

into

the

control

equation.

tlastic

feedback

fiom

iotor

currerrt

variations

Lem

turned

on,

t,.ben the automalic

excitation

lt'

what

js

the.purpose.of

resistors

r,

tbrough

rs

in

the

devices

of the

EpA-szsB

[3111

?:ifi)

automatii

coltiolle.;

*;;

ror

[ererat6rs

rurnlshia

"'iiiii,i]hlirrsu.o"s,excirers

{2'

Hos'is

the

setting.of

tbe

voltage

relay

of

the

excitation

forcing

de.r,jce

se}ected?

lvbv

is

it

desirabte.

tor

ti,is-r;i;r";;

h:q;r-"

i,gi,.i'

rJset-to-pickup

ratio?

13'

!t?hat

are

tbe

actions

oi'attendinq

personnel

.".h;o'"o;t;;;iios".r";itrtion

forcrng

devices

of

generators

provided

o'it[-

ortu"a]l

irnd

forced

eooling

of

.t-h-e

rotor

u.indings?

14'

How

can

a

sigial

proportioo"f

io-tt"

;fi";;i;;

of

tbe

variable

under

m€asureme'r

be

formed?

"

r--r-'

15'

What

is the-purpoi;g

of

the

individual

units

employed

in

tbe

oreractjon

controller

designed

bv the

All-u;ioi

eteii.i."t

b;;i;;il;s

iir:tiiiliii

ro.

the

diagram

of rrre

con*oller

see

Fig.

1-20.

0./77F

58

CEAPTER ONE

U,

=

Arc

Uo=

U"a

Fig.

1-22.

Explanatory

diagrams

vector difference

between

the

currents

in

phase

,{

and

phase

C.

The

magnetic

flux

built

up

bv this cupent

in

the

?

v,inding is

{ba

-hyl7.

As the

Z

winding--is in

opposition.to

the

tV

winding,

the flux

direction

oriented

relative

to the

direction

of

the

llux

burlt up

,by lPe

current

fio*' in

the

ff v'inding

is

of

the opposite

polarity

and is determined

in

space

by

tbe

oertor

Oi".

The

primary

windings

of the

PZ

transforrner

are

connected

to

tbe

interphase

voitages

!Oryr,!^r^r,,|?d,,gqn

These

volrages.co*e,qpond_ro

the

volrages

i^r-,-i;.;"d

ii.

on

the

star

side of the

7?

transformer.

The

n winding

of

the

iransioriler

?"lit

is"connected

to

the

vector

difference

between

the

voltag".

u6.

-

ab

-

u"

The

cunent

^r^*

determining

tbe

direction

of

the

flux

<iro

lags

the

u6. voltage

vector

by 60

deg.

Ii

is seen

f.rom

Fig.

t-Zzb

that,

as

this

happens,

the

flux

O*

will

iag

the

fiux

Oi

lV

g0

deg.

Tbe

resultart

ifu

A"".

(Fig'

t-22c)

determined

by the

vector

sum

of the

flures

<bn,

and

cD7

will

be

at

its

minimum.

with

an

increase

in-the

angle.,g,the

dbsolute

value

of

the

itux

rir"".-

rir..

".ra

*,ill

be

at

its

maximum

at

the

an^cl9_e-l-

90'deg.

It

is seen

fron

iir"tia.gram

in Fig.

i-10

that

the

rotor

current

is

dependent

on'the

magnitude

of the

flux

o;*-;'i"iil-i-*i'oTing'ir

the

transfor_

mer

TM.

AUTOMATIC

CONTRO!

OF

SYNCERONOUS

GENERA?OR

EXCIIATION,

59

F

{')

Startor circait

Resullan[

effeet

on

rolor

circui{

Iltrou"oh lll

\

s

q

\

q

e

R

\,

t

(c)

AUTOMATIC

VOLTAGE

REGULATIONChapter

Tuto

AUTOMATIC

VOLTAGE REGULATION

2-1.

General

h{aintaining

the

normal

voltage

in

a

power system

is one

of the

basic

ways

of

assuring

itJ

proper

performance. The

State

Standardt2-tl

specilies

that

the

maximum-permitted

voltage variation

at

the

load

terminals shouid

not

exceed

:t5

per

cent

of

the

rated

value.

Voltage

drop

beyond

t,he

specified

limits

mal

resuit

in

excessive

slippage

of

asyncbronous

motors with

resuitant

reactive

current

overload

of

the feeding

elements

and decreased

}uminous efficiency

of

:r=rlir"-"i

oo*ito*as

+-o

the

s5rstem

fle.ding

elsmsnt,s,

proper

loading and

unioad-

ing of individual

transmission

lines

and

appropriate selection

of

transformation

raiios

for step-up

and

step-down

transformers)

and also b1'

joint

operation

of

automatic

exlitation

controllers

of

asynclrronous

generators and

synchronous

eapacitors,

devices

which automatically

change,

when under

load,

the

trans-

foimation

ratios

of

power

transformers, remote

transformer

boosters

and

devices

*,!,iaI" o::*nnnofincllrr eu'itnh !1a-7or

flT e-nntinttorrslt;

rJeT\-r

t.hg canaCitivg

IOad

yvIlIU.ll

cLLIUlruouIwqlrJ

onrovu v

rer

vv!vrsqvqerJ

of

static balancers.

2-2. Use

of

AEC

Devices

Automatic, excitation

controllers

are used

to

maintain

the voltage

in

com-

pliance

with

the specified

characteristic

and

distribute

the

reactive

load

between

the

power

sources

under normal

operating

conditions

of

power

systems.

When

generators and

synchronous capacitors

are equipped

with AEC

apparatus,

a cbange

in

the

required

voltage

setting

is

accompijsLred by

special

automatic

devices,

i.e.,

voltage

controllers

or through

setting

devices

operated

by

attend-

ing

personnsl.

To

dccrease

the

voltage

ae.ross

the

terminals

of

a

generator

or

a synchronous

;:t1"j'i,::":':*i*"::f:T'ji:*::.:::'.l: :.':I 11

*'-'-"

th'

;."f9,s""pprieJ

geqr

eresEuuo

vl

r,trt

yuroage

gorrgcf,or.

In

tnr_s

casg

thg

output

current

of

the

corrector

oecreases.

To

increase

the

termiaal

voltage

of the generator

or synchronous

capacitor,

the.

voltage

imposed

on the

lineir

and

noilio""t

Li.*."ir

or

tu!1"rtif.

"".1

rector

must

be

decreased.

This

decrease

is permissible

up

.to

a

-certain

limit

6t

Fig.

2-1.

Parallel

operation

of

ge.nerators

connected

into

common

voltase

busbars

dictated

by

the

value

of

tire

maximum.

output

current

of the

yoltage

corrector.

The

output

current

of the

corrector

is

indiiated

on

a

control

p"ori'instrument.

_

The

problem

of

voltage

and reactjl'e

p.ower

reguia!o^n-i;;;;*.,

sv-srem,

however,

oannot

be completely

solved

b-v'the

nr.

If

egCae'ic.Ilo

generators

and synchroDous

capacitors

without

inteivention

by

duty

t;r;;;uj.

Considered

belou'

are some

examnles which e,ler.ift-, r.prt.*in n-i-^i*-!^-

=-=^r^-r-

o

r AE

c

d e v i

ces r;

;;;

;" t

i"s iil.

";i

;"g;;d

;

^:;

ffi

'#;A

i

l":",ii

Ii lf"

;T

J::

in

power

systems.

The

generators,

oyergle

in

ryyallel

into_the

generator

uoltage

busbars.

Each

generator

ts

furni'shed

with

an

AEC deuice.

The

bisbar

uoltage

*|,tt-Ut

mai,ntained.

at

a specifi,ed

ualue

(Fig.

2-1).

By

convention,

the

regulation

proc

range. For

the

AEC's,

the

regulating

ra

region

in

which the

exciter

operates

u

determining

a

critical

exeitatibn

amoul

by

the

exciter

design

(its

electromag!

Barzam A.B. Automation in Electrical Power Systems (Системная автоматика)

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