power system stability prime mover-governor

8/9/2019 Power System Stability Prime Mover-governor

1/27

IEEEG1

• A common stream turbine model, is the IEEEG1,originally introduced in the below 1973 paper

1IEEE Committee Report, “Dynamic Models for Steam and Hydro Turbines in Power System Studies,Transactions in Power !pparatus " Systems, #olume $%, &o' (, &o#')Dec' *$+, pp *$-./*0

In t1is model 23*)RIt can be used to represent

cross/compound units, wit1

1i41 and low pressure steam

5o and 5c are rate

limits


2/27

IEEEG1

• Blocks on the right model the arious steam stages• About 1!" o# $E%% goernors are currently IEEEG1s

• Below #igures show two test comparison with this

model with one matching well and one not

!Ima4e Source6 7i4s %/., %/( of IEEE PES, 8Dynamic Models for Turbine/9o#ernors in Power System Studies,8 :an %-*


3/27

Deadbands

• Be#ore going #urther, it is use#ul to brie#ly considerdeadbands, with two types shown with IEEEG1 and

described in the !&13 IEEE 'E( Goernor )eport

• *he type 1 is an intentional deadband, implemented to

preent e+cessie response

–ntil the deadband actiates there is no response, then

normal response a#ter that- this can cause a potentially

large .ump in the response

–Also, once actiated there is normal

response coming back into range

–sed on input to IEEEG1

3


4/27

Deadbands

• *he type ! is also an intentional deadband,implemented to preent e+cessie response

–/i##erence is response does not .ump, but rather only starts

once outside o# the range

• Another type o# deadband is theunintentional, such as will occur

with loose gears

–ntil deadband 0engages0

there is no response

–nce engaged there is

a hysteresis in the

response

2


5/27

Deadband Example: ERCOT

• 'rior to oember !&&4, E)%* re5uired that thegoernor deadbands be no greater than 68 &&3: ;<

• A#ter 113&4 deadbands were changed to 68 &&1:: ;<

=

%--; did1a#e

two

mont1s

wit1 t1e

lower #alues

Ima4e Source6 Sydney &iemeyer, &R9, %)$)*- presentation to TeT?


6/27

Gas Turbines

• A gas turbine >usually using natural gas? has acompressor, a combustion chamber and then a turbine

• *he below #igure gies an oeriew o# the modeling

:Ima4e from IEEE PES, 8Dynamic Models for Turbine/9o#ernors in Power System Studies,8 :an %-*

HRS9 is

t1e 1eat

reco#ery

steam

4enerator =if it is a

combined

cycle unit?


7/27

GAST Model

• @uite detailed gas turbine models e+ist- well .ustconsider the simplest, which is still used some

7

It is somew1at similar

to t1e T9>@*' T*

is for

t1e fuel #al#e, T%is for t1e turbine, and

T is for t1e load

limit response based

on t1e ambient

temperature =!t?A

T is t1e delay in

measurin4 t1e e


8/27

Play-in Playba!"# Models

• #ten time in system simulations there is a desire to testthe response o# units >or larger parts o# the simulation?

to particular changes in oltage or #re5uency

–*hese alues may come #rom an actual system eent

• 0'lay8in0 or playback models can be used to ary anin#inite bus oltage magnitude and #re5uency, with data

speci#ied in a #ile

•'ower$orld allows both the use o# #iles >#or sayrecorded data? or auto8generated data

–achine type GE%C(D'CABA%F can play back a #ile

–achine type In#initeBus(ignalGen can auto8generate a

signal 4


9/27

Po$er%orld In&ini'e (us

Si)nal Genera'ion

• Below dialog shows some options #or auto8generationo# oltage magnitude and #re5uency ariations

9

S'ar' Time tells w1en to startA #alues are

t1en defined for up to fi#e separate time

periods

*ol' Del'a is t1e ma4nitude of t1e pu

#olta4e de#iationA *ol' +re, is t1e

freBuency of t1e #olta4e de#iation in H

=ero for dc?

Speed Del'a is t1e ma4nitude of t1efreBuency de#iation in HA Speed +re, is

t1e freBuency of t1e freBuency de#iation

Dura'ion is t1e time in seconds for t1e

time period


10/27

Example: S'ep Can)e *ol'a)e

Response

• Below graph shows the oltage response #or the #our bus system #or a change in the in#inite bus oltage

1&

@ =pu?us us %gfffff @ =pu?us us .ffffff

*-$;+(0.%*-

*'*%0

*'*%

*'**0

*'**

*'*-0

*'*

*'-$0

*'-$

*'-;0

*'-;

*'-+0

*'-+

*'-(0

*'-(

*'-00

*'-0

*'-.0

*'-.

*'-0

*'-

*'-%0

*'-%

*'-*0

*'-*

*'--0

*

Case name6 .Si4nal9enIEEE9%


11/27

Simple Diesel Model: DEGO*

• (ometimes models implement time delays >/EG? –#ten delay alues are set to


12/27

DEGO* Delay Approxima'ion

• $ith */ set to &= seconds >which is longer than normal

in order to illustrate the delay?

1!

Transien' S'abili'y Time S'ep Resul's *ariables

9en us . F* States of 9o#ernorG!ctuator

9en us . F* >t1er 7ields of 9o#ernorGEn4ine

Time

0.';.'(.'..'%.';'('.'%%';%'(%'.%'%%*';*'(*'.*'%*-';-'(-'.-'%-

@ a l u e s

*'%

*'*$

*'*;

*'*+

*'*(

*'*0

*'*.

*'*

*'*%

*'**

*'*

*'-$

*'-;

*'-+

*'-(

*'-0

*'-.

*'-

*'-%

*'-*

*


13/27

.ydro /ni's

• ;ydro units tend to respond slower than steam and gasunits- since early transient stability studies #ocused on

.ust a #ew seconds >#irst or second swing instability?,

detailed hydro units were not used

–*he original IEEEG! and IEEEG3 models .ust gae the linearresponse- now considered obsolete

• Below is the IEEEG!- le#t side is the goernor, right

side is the turbine and water column

13

7or sudden c1an4es

t1ere is actually an

in#erse c1an4e in

t1e output power


14/27

+our (us $i' an IEEEG0

• Graph below shows the mechanical power output o#gen ! #or a unit step decrease in the in#inite bus

#re5uency- note the power initially goes downH

12Case name6 .Si4nal9enIEEE9%

Speed9en us % F*gfffff Mec1 Input9en us . F*ffffff

*-$;+(0.%*-

(-

0$'$0

0$'$

0$';0

0$';

0$'+0

0$'+

0$'(0

0$'(

0$'00

0$'0

0$'.0

0$'.

0$'0

0$'

0$'%0

0$'%

0$'*0

0$'*

0$'-0

0$

*+0

*+-

*(0

*(-*00

*0-

*.0

*.-

*0

*-

*%0

*%-

**0

**-

*-0

*--

$0

$-

;0

;-

+0

+-

(0

P1ysically t1is iscaused by a transient

decrease in t1e water

pressure w1en t1e

#al#e is opened toincrease t1e water

flow


15/27

IEEEG

• *his model has a more detailed goernor model, but thesame lineariresulting in less o# a power change?

1=

ECC 1as

about *- of

t1eir 4o#ernorsmodeled wit1

IEEE9s


16/27

%asou' +il'ers

• A washout #ilter is a high pass #ilter that remoes thesteady8state response >ie, it 0washes it out0? while

passing the high #re5uency response

• *hey are commonly used with hydro goernors and >as

we shall see? with power system stabili


17/27

IEEEG +our (us +re,uen!y Can)e

• *he two graphs compare the case response #or the#re5uency change with di##erent ) temp alues

17

Speed9en us % F*gfffff Mec1 Input9en us . F*ffffff

*-$;+(0.%*-

(-

0$'$0

0$'$

0$';0

0$';

0$'+0

0$'+

0$'(0

0$'(

0$'00

0$'0

0$'.0

0$'.

0$'0

0$'

0$'%0

0$'%

0$'*0

0$'*

0$'-0

0$

*-+

*-('0

*-(

*-0'0

*-0

*-.'0

*-.

*-'0

*-

*-%'0

*-%

*-*'0

*-*

*--'0

*--

$$'0

$$

$;'0

$;

$+'0

$+

Rtemp 3 -'0, Rperm 3 -'-0

Speed9en us % F*ffffff Mec1 Input9en us . F*ffffff

*-$;+(0.%*-

(-

0$'$0

0$'$

0$';0

0$';

0$'+0

0$'+

0$'(0

0$'(

0$'00

0$'0

0$'.0

0$'.

0$'0

0$'

0$'%0

0$'%

0$'*0

0$'*

0$'-0

0$

**+

**(

**0

**.

**

**%

***

**-

*-$

*-;

*-+

*-(

*-0

*-.

*-

*-%

*-*

*--

$$

$;

$+

Case name6 .Si4nal9enIEEE9%

Rtemp 3 -'-0, Rperm 3 -'-0


18/27

(asi! 2onlinear .ydro Turbine Model

• Basic hydro system is shown below –;ydro turbines work be conerting the kinetic energy in the

water into mechanical energy

– assume the water is incompressible

• At the gate assume a elocity o# , a cross8sectional penstock area o# A- then the

olume #low is AJ@-

14Source6 $'%, 2undur, Power System Stability and Control , *$$.


19/27


• Krom ewtons law

• As per LaM paper, this e5uation is normali


20/27


• $ith h base the static head, 5 base the #low when the gate is

#ully open, an interpretation o# *w is the time >in

seconds? taken #or the #low to go #rom stand8still to #ull

#low i# the total head is h base

• I# included the head losses, hloss, ary with the s5uare o#

the #low

• *he #low is assumed to ary as linearly with the gate

position >denoted by c?

!&

or

2q

q c h hc

= = ÷


21/27


• 'ower deeloped is proportional to #low rate and head,with a term 5nl added to model the #i+ed turbine >no

load? losses

–*he term At is used to change the per unit scaling to that o#

the electric generator

!1

( )m t nl P A h q q= −


22/27


23/27

4ineari5ed Model Deri6a'ion

• *he preiouslymentioned

lineari ?

> ?

And #or the lineari


24/27

+our (us Case $i' .3GO*

• *he below graph plots the gate position and the poweroutput #or the bus ! signal generator decreasing the

speed then increasing it

!2

Mec1 Input9en us . F*gfffff

States of 9o#ernorG9ate9en us . F*ffffff

*-$;+(0.%*-

**%

***

**-

*-$

*-;

*-+

*-(

*-0

*-.

*-

*-%

*-*

*--

$$

$;

$+

-'$(

-'$00

-'$0

-'$.0

-'$.

-'$0

-'$

-'$%0

-'$%

-'$*0

-'$*

-'$-0

-'$

-';$0

-';$

-';;0

&ote t1at Lust

lie in t1elinearied

model, openin4

t1e 4ate

initially

decreases t1e

power output


25/27

PID Con'rollers

• Goernors and e+citers o#ten use proportional8integral8deriatie >'I/? controllers

• 'I/s combine

–'roportional gain, which produces an output alue that is

proportional to the current error

– Integral gain, which produces an output alue that aries with

the integral o# the error- this will eentually drie the error to


26/27

PID Example: Posi'ion Con'rol

• (ay we wish to get an ob.ect to a position in 18dimensional space by controlling its acceleration >#orce?

–Error is distance #rom desired position

–%ontrol is speed

• $ith .ust proportional control, acceleration will bedecreasing, but wed reach ma+imum speed at the

desired point, oershooting

•$ith deriatie control, well be slowing down,aoiding the oershoot

• *he integral term will make sure we stay at the desired

point

!:


27/27

.3G

• *he ;G3 models either a 'I/ or a double deriatie

!7

Noos more

complicated

t1an it is

sincedependin4

on cfla4

only one of

t1e upper pat1s is

used

power system stability prime mover-governor

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