zahids presentation (2)

7/25/2019 ZAHIDS Presentation (2)

1/22

Study of SMES Technology & its Integration to AGC

Introduction:

Power-system stability is a term applied to alternating-current electric power systems,

denoting a condition in which the various synchronous machines of the system remain in

synchronism, or "in step," with each other. Conversely, instability denotes a condition

involving loss of synchronism, or falling out of step."

Fig. 1 eactance model of a simple power system

!enerator, otor reactance into a single reactanceX, we have an electric circuit consisting

of two constant-voltage sources,EgandEm, connected through Consider the simple power

system of Fig. 1, consisting of a synchronous generator supplying power to a synchronous

motor over a circuit composed of series inductive reactance XL. #ach of the synchronous

machines may be represented, at least, by a constant-voltage source in series with a constant

reactance. $hus the generator is byEgandXg; and the motor, byEm andXmupon combining

the machine reactance%s and the line. eactance & ' XG (XL(XM. )t will be shown that the

power transmitted from the generator to the motor depends upon the phase difference of the

two voltagesEgandEM. *ince these voltages are generated by the flu+ produced by the fieldwindings of the machines, their phase difference is the same as the electrical angle between

the machine rotors.

P=EgEmsin/X 1

Page 1


2/22

$he ma+imum power that can be transmitted in the steady state with the given reactance

& and the given internal voltagesEgandEM . )f a large increment of load on the motor is

added suddenly, instead of gradually, the motor may fall out of step even though the new

load does not e+ceed the steady-state stability limit. $he reason is as follows /hen the large

increment of load is added to the motor shaft, the mechanical power output of the motor

greatly e+ceeds the electrical power input, and the deficiency of input is supplied by

decrease of 0inetic energy. $he motor slows down, and an increase of the displacement

angle and a conseuent increase of input results. )n accordance with the assumption that the

new load does not e+ceed the motor slows down, and an increase of the displacement angle

and a conseuent increase of input results. )n accordance with the assumption that the new

load does not e+ceed the steady-state stability limit, increases to the proper value for steady

state operation, a value such that the motor input euals the output and the retarding torue

vanishes. /hen this value of torueis reached, however, the motor is running too slowly. )ts

angular momentum prevents its speed from suddenly increasing to the normal value. 2ence

it continues to run too slowly, and the displacement angle increases beyond the proper value.

3fter the angle has passed this value, the motor input e+ceeds the output, and the net torue

is now an accelerating torue. $he speed of the motor increases and approaches normal

speed. 4efore normal speed is regained, the motor input decreases to a value less than the

output. )f this, the net torue changes from an accelerating torue to a retarding torue. $he

speed, which is still below normal, now decreases again, and continues to decrease during

all but a small part of each slip cycle. *ynchronism is definitely lost. )n other words, the

system is unstable. )f, however, the sudden increment in load is not too great, the motor

will regain its normal speed before the displacement angle becomes too great. $hen the net

torue is still an accelerating torue and causes the motor speed to increase and thus to

become greater than normal. $he displacement angle then decreases and again approaches

its proper value.

3gain it overshoots this value on account of inertia. $he rotor of the motor thus oscillates

about the new steady-state angular position. $he oscillations finally die out because of

damping torues, which have been neglected in this elementary analysis. 3 damped

oscillatory motion characteri5es a stable system ./ith a given sudden increment in load,

there is a definite upper multi machine systems..ost power systems have many generating

Page 2


3/22

stations, each with several and many loads, most of which are combinations of synchronous

motors, synchronous condensers, induction motors, lamps, heating devices, and others. $he

stability problem on such a power system usually concerns the transmission of power from

one group of synchronous machines to another. 3s a rule, both groups consist predominantly

of generators. 6uring disturbances the machines of each group swing more or less together7

that is, they retain appro+imately their relative angular positions, although these vary greatly

with respect to the machines of the other group. For purposes of analysis the machines of

each group can be replaced by one euivalent machine. )f this is done, there is one

equivalent generator and one euivalent synchronous motor, even though the latter often

represents machines that are actually generators. $he important discussion lies in the power

system stability. 3utomatic generation control 3!C, is a ma8or control function within a

utility9s energy control center, whose purpose is the trac0ing of load variations while system

freuency, net tie-line interchanges, and optimal generation levels close to specified values.

/hen several utilities are interconnected, each will perform its 3!C independently of the

others. $his decentrali5ed control system has wor0ed uite well since its in the fifties, in

spite of the fact that at that time, the only control theory tools available were those of

classical freuency-domain, single-input single-output, systems. $hus 3!C is a true

predecessor of the much highlighted recent approaches of hierarchical modern control

theory. $he success of 3!C may be attributed to two important considerations. $he first is

related to the fact that feedbac0 controlwill almost always tend to stabili5e and regulate the

system being controlled. 3nd the second is due to the clever design of 3!C by its

originators in a manner that guaranteed the correct steady-state response of the entire

system.

*ince the transient response will depend on the dynamics of generators, loads, and

feedbac0 control parameters, the original designers of 3!C had to depend on highly

simplified models at the design stage, and on actual system response, in order to tunethe

control system parameters.

Page 3


4/22

Fig. : !eneral 4loc0 6iagram for a Power !enerating *ystem

$he )ssues *ingle !enerator and )ts response figure above provide a general bloc0

diagram for a generating system. $he turbo-generator receives two 0ey input uantities

mechanical power inputPM in the form of rotating shaft power from the turbine7 and field

voltageEFDfrom the e+citer. $he 0ey outputs are a the generated electric power PG+ ;

b terminal voltage Vt, and c angular speed w. $hese outputs are measured sensed by

appropriate devices, and then used, in a feedbac0 fashion, to control the system. $he angular

freuency wis compared with the rated or desired freuency wo. $he resulting freuency

error isthen amplified in the turbine-governor feedbac0 loop by the factor 1= R and from

the esire real power generation P9

*imilarly, in the e+citer feedbac0 loop, the error signal is an input to the e+citer. 3

supplementary error signal is sometimes used to influence the output of the e+citer for the

purpose of damping slow power oscillations. $he bloc0 P**in Figure refers to the so-called

Power *ystem *tabili5er4y itself, this bloc0 diagram should tell us a few important things.

>nder steady-state conditions one would e+pect all error signals to be 5ero implying that

>nder dynamic conditions, it implicitly shows that the control of generated power and

freuency will be accomplished mainly by the governor-turbine system and secondarily by

the e+citer. ?n the other hand, the main role of the e+citer is to control the terminal voltage,

with a secondary role in stabili5ing power oscillations. /ithout going into the detailed

models themselves, some 0ey facts are in order. 4asically, the governor-turbine system is

slow reactingwhen compared with the e+citation system, which is fast reacting.3s a result,

fluctuations in voltage can be corrected by the e+citation system, very uic0ly typically

within 1@ to A@ m sec

Page 4


5/22

Fluctuations in generated power or freuency are corrected slowly, in the time framewor0

of .A-1@ sec. Bow since governor-turbine control has little on the terminal voltage, one can

decouple the governor- loop from the e+citation loop. )n essence, one can study the governor

turbine control loop with its influence on and freuency under the assumption that terminal

voltage is maintained at its value always. For short in the order of a fraction of a second, one

may also decouple the governor-turbine control loop and study e+citation system responses.

>nder these conditions, the mechanical power Pis 0ept constant at its nominal value P9.3

longer-term e+citer response will, however, reuire the inclusion of both control loops in the

study model. *ince 3!C is primarily concerned with the real power=freuency behavior of

the system, the e+citation system model will not be reuired. $his important simplification

paves the way for the governor turbine model shown in Figure below. )n this model, the

governor is represented by a bloc0 with one time constant $!, which is typically in the range

of @.1-@.: sec. $he turbine, by a bloc0 with the time constant $$, which is typically about

sec.7 and the generator inertial response by the swing euation where M is the machine9s

inertia constant, andD is a damping coefficient

Fig. *imple !enerator 4loc0 6iagram with 3ssociated !overnor turbine odel

Page 5


6/22

Fig. D*imple !enerator 4loc0 6iagram of 3ssociated !overnor turbine odel with speed

droop characteristics

' @

EPC 'P P@

EP6 ' P6 - P@

!

:

3nd freuency, one may define the incremental uantities where P6 is the load. $he

conseuence is shown in the bloc0 diagram of Figure for the so-called incremental

generator model. )n that figure, the following state variables are identified as indicated is

the output of the governor bloc0 valve displacement to inlet steam to turbine. )n state

Gariable form, the state euations the system are given by-

Page 6


7/22

Fig. A Humped 4loc0 6iagram of 3ssociated !overnor turbine odel with speed droop

characteristics

d x1

dt =

1

M(D x

1+x

2P)

d x2

dt =

1

TT(x

3x

2)

d x3

dt =

1

TG(x3+ PC x1R )

)n this system of euationsPDrepresents an input disturbance associated with load changes,

whereas .P! represents the increment in thes"ee !#angerposition which controls increases

or decreases in power demand. $he following e+ample should illustrate some of the 0ey

issues.

Load Model

*ince many loads are freuency-sensitive, the incremental change in load will have a

freuency-dependent part, i.e., where,

EP6' EP@ ( D

D= PD

Page 7


8/22

x1=

'1

D+D+1 /R P D D

epresents the sensitivity of the load to freuency changes at the nominal value of the load

3 0ey conclusion from the above steady-state analysis is that the inverse of the regulation

constant R is li0e a am"ing !oe$$i!ient. $his is also true of the coefficient D% of load

freuency sensitivity. )n fact, it is easy to show that, in the steady-state .

Integral Control:

)n order to eliminate the freuency steady-state error, the loo" may be closed on the speed

!#anger inputP!. Hetting ID be a new state variable which is the integral of the freuency

error, i.e.

d x4

dt=x

1

$henP! will become a$ee&a!' signal given by

EPC' K

Ix

4 A

/here()is a feedbac0gain constant. )n order to determine the steady-state response to a

step-input in the load, we set all first order time derivatives to 5ero. From the above

definition of ID, one easily concludes the fact, it should be clear that as long as ID is part of

the feedbac0 control signal e.g., it may be combined linearly with other variables in the

feedbac0 loop, then the -state error is 5ero.

Response to a Random istur!ance:

)n the previous analysis, the assumed disturbance was aste" in"ut in the load. )n reality,

system load disturbances are uite comple+ and random in nature. $ypically, load variations

comprise a slowly changing tren component over which are superimposed fast random

fluctuations. *tep load inputs will occur only occasionally as a result of special

circumstances li0e the loss of a generating unit, the switching of a large electric arc furnace,

Page 8


9/22

and the li0e. *ince the incremental generator model used above is linear, one may study

system response to every !om"onent of the load disturbance, and then employ the principle

of superposition to obtain a realistic idea about the overall response. )n this section we shall

investigate the single generator response to a stochastic w#ite noise load disturbance. )n

order toJ do so, an important result from stochastic control theory.

!eneration and distribution of electric energy with good reliability and uality is very

important in power system operation and control. $his is achieved by 3utomatic !eneration

Control 3!C. )n an interconnected power system, as the load demand varies randomly, the

area freuency and tie-line power interchange also vary. $he ob8ective of Hoad Freuency

Control HFC is to minimi5e the transient deviations in these variables and to ensure for

their steady state values to be 5ero. $he HFC performed by only a governor control imposes

a limit on the degree to which the deviations in freuency and tie-line power e+change can

be minimi5ed. 2owever, as the HFC is fundamentally for the problem of an instantaneous

mismatch between the generation and demand of active power, the incorporation of a fast-

acting energy storage device in the power system can improve the designing for controllers

based on these techniues, the perfect model is reuired which has to trac0 the state

variables and satisfy system constraints. $herefore it is difficult to apply these adaptive

control techniues to 3!C in practical. )n multi-area power system, if a load variation

occurs at any one of the areas in the system, the freuency related with this area is affected

first and then that of other areas are also affected from this perturbation through tie lines.

/hen a small load disturbance occurs, power system freuency oscillations continue for a

long duration, even in the case with optimi5ed gain of integral controllers. *o to damp out

the oscillations in the shortest possible time, automatic generation control including *#*

unit is proposed.

$herefore, in the proposed control system, with an addition of the simple *#* controller,

a supplementary controller with K is designed in order to retain the 3 superconducting

magnetic energy storage system is a 6C current device for storing and instantaneously

discharging large uantities of power. $he 6C current flowing through a superconducting

wire in a large magnet creates the magnetic field. $he large superconducting coil is

contained in a cryostat consisting of a vacuum vessel and a liuid vessel that cools the coil.

3 cryogenic system and the power conversion=conditioning system with control and

Page 9


10/22

protection functions are also used to 0eep the temperature well below the critical

temperature of the superconductor. 6uring *#* operation, the magnet coils have to remain

in the superconducting status. 3 refrigerator in the cryogenic system maintains the reuired

temperature for proper superconducting operation. 3 bypass switch is used to reduce energy

losses when the coil is on standby. 3nd it also serves other purposes such as bypassing 6C

coil current if utility tie is lost, removing converter from service, or protecting the coil if

cooling is lost LFigure below shows a basic schematic of an *#* system >tility system

feeds the power to the power conditioning and switching devices that provides energy to

charge the coil, thus storing energy. /hen a voltage sag or momentary power outage occurs,

the coil discharges through switching and conditioning devices, feeding conditioned power

to the load. $he cryogenic refrigeration system and helium vessel 0eep the conductor cold

in order to maintain the coil in the superconducting state.

Fig. M *#* system >tility

$here are several reasons for using superconducting magnetic energy storage instead of

other energy storage methods. $he most important advantages of *#* are that the time

delay during charge and discharge is uite short. Power is available almost instantaneously

and very high power output can be provided for a brief period of time. ?ther energy storage

methods, such as pumped hydro or compressed air have a substantial time delay associated

Page 10


11/22

with the conversion of stored mechanical energy bac0 into electricity. $hus if a customer9s

demand is immediate, *#* is a viable option. 3nother advantage is that the loss of power

is less than other storage methods because the current encounters almost 5ero resistance.

3dditionally the main parts in a *#* are motionless, which results in high reliability.

3lso *#* systems are environmentally friendly because superconductivity does not

produce a chemical reaction. )n addition, there are no to+ins produced in the process. $he

*#* is highly efficient at storing electricity greater than NO efficiency, and provide

both real and reactive power. $hese systems have been in use for several years to improve

industrial power uality and to provide a premium-uality service for individual customers

vulnerable to voltage and power fluctuations. $he *#* recharges within minutes and can

repeat the charge=discharge seuence thousands of times without any degradation of the

magnet. $hus it can help to minimi5e the freuency deviations due to load variations.

2owever, the *#* is still an e+pensive device.

SMES for Load "re#uency Control application:

3 sudden application of a load results in an instantaneous mismatch between the demand

sudden and supply of electrical power because the generating plants are unable to change the

inputs to the prime movers instantaneously. $he immediate energy reuirement is met by the

0inetic of the generator rotor and speed falls. *o system freuency changes though itbecomes normal after a short period due to 3utomatic !eneration Control. 3gain, sudden

load re8ections give rise to similar problems. $he instantaneous surplus generation created

by removal of load is absorbed in the 0inetic energy of the generator rotors and the

freuency changes. $he problem of the freuency from normal value under such

circumstances is 0nown as t#e loa $requen!y !ontrol "ro&lem. $o be effective in load

freuency control application, the energy storage system should be fast acting i.e. the time

lag in switching from receiving charging mode to delivering mode should be very small.

For damping the swing caused by small load perturbations the storage units for HFC

application need to have only a small uantity of stored energy, though its power rating has

to be high, since the stored energy has to be delivered within a short span of time. 2owever,

due to high cost of superconductor technology, one can consider the use of non-

superconducting of lossy magnetic energy storage *#* inductors for the same purpose.

Page 11


12/22

*uch systems would be economical maintenance free, long lasting and as reliable as

ordinary power transformers.

$hus a *#* system seems to be good to meet the above reuirements. $he power flow

into an energy storage unit can be reversed, by reversing the 6C voltage applied to the

inductor within a few cycles. 3 1:-pulse bridge converter with an appropriate control of the

firing angles can be adopted for the purpose. $hus, these fast acting energy storage devices

can be made to share the sudden load reuirement with the generator rotors, by continuously

controlling the power flow in or out of the inductor depending on the freuency error

signals.

$he *#* inductor converter unit for improvement in power system HFC application

essentially consists of a 6C inductor, an ac=dc converter and a step down Q-Q=E transformer.

$he inductor should be wound with low resistance, large cross-section copper conductors.

$he converter is of the 1:-pulse cascaded bridge type shown in Fig. :, connected to the

inductor in the 6C side and to the three-phase power system bus through the transformer in

the ac side Control of the firing angles of the converter enables the 6C voltage applied

Gsm to the inductor to be varied through a wide range of positive and negative values as

shown in Fig. . !ate turn off thyristors !$?.

Page 12


13/22

Fig O #ffect of inductor voltage, Gsm )sm

c'@.@@ R

c'@.@A R

c'@.1@ R

/ith the variation of firing angle of 1:-pulse converter allow us to design such type of

converter. /hen charging the magnet, a positive 6C voltage is applied to the inductor. $he

current in the inductor rises e+ponentially or linearly and the magnetic energy is stored.

/hen the current reaches the rated value, the applied voltage is brought down to low value,

sufficient to overcome the voltage drop due to inductor resistance. /hen the e+tra energy is

reuired in the power system, a negative 6C voltage is applied to the inductor by controlling

the firing angles of the converter. $he losses in the *#* unit would consist of the

transformer losses, the converter losses, and the resistive loss in the inductor coil. $he

inductor loss can be 0ept at an acceptable level by proper design of the winding.

6ue to sudden application or re8ection of load, the generator speed fluctuates. /hen the

system load increases, the speed falls at the first instant. 2owever, due to the governor

action, the speed oscillates around some reference value. $he converter wor0s as an inverter

Page 13


14/22

N@ ST S:O@ when the actual speed is less than the reference speed and energy is withdrawn

from the *#* unit . 2owever, the energy is recovered when the speed swings to the other

side. $he then wor0s as a rectifier -N@ ST SN@ and the power P becomes positive. )f the

transformer and converter losses are neglected, according to the circuit analysis of

converter, the voltage Gsm of the 6.C side of the 1:-pulse converter under eual-T when a1

' a:' T mode is e+pressed by

2

C

cos1+ cos=2v smocos2ISMR

VSM=VSMO

M

/here G* is the 6C voltage applied to the inductor

)smis the current through the inductor

smis the euivalent commutating resistance and Gc is the ma+imum open circuit bridge

voltage of each M-pulse bridge at T '@@.

/hen the inductor is charged initially, the current build up, e+pressed, as a function of

time with Gsm held constant, is given as where H and

sm=

VSM[1R! t

! ]R!

I

O

/here H and are the inductance and the resistance of inductor respectively.

?nce the current reaches its rated value ) it is held constant by reducing the voltage to a

value Gsm enough to overcome the resistive drop. )n this case

VSM=I

SMOR

!

U

/here, 3s this value of Gsm@ is very small, the firing angle will be nearly N@

. 3t any instant of time the amount of energy stored in the inductor is given by

Page 14


15/22

SM="SM0+

t

t

Psm

d#

"

N

is the initial energy in the inductor.

/here,

SMo=1

2

"H I

2

?nce the rated current in the inductor is reached, the unit is ready to be coupled with the

power system application. $he freuency deviation Ef of the power system is sensed and fed

to the *#* unit as the error signal. EG is then continuously controlled depending on

controlled depending on this signal. /hen there is a sudden increase in load in the powersystem, the freuency falls and a negative voltage, e+pressed by euation

$ VSM=K0 $% 1@

is impressed on the inductor. $he converter bridges maintain a unidirectional current flow

and as the circuit is inductive the current does not change instantaneously. )n this mode of

operation, a positive converter voltage produces positive power, which means charging the

coil, and a negative converter voltage produces a negative power and discharges the

inductor. /hen the freuency dip in the power system causes a negative voltage to be

applied to the inductor, power flows from the inductor into the power system, sharing the

sudden load reuirement. $he reverse process ta0es place when there is a sudden load

re8ection in the power system. $he freuency increase causes a positive voltage to be

impressed on the inductor and the *#* unit absorbs the e+cess power from the power

system. $he conceptual diagram of active and reactive power modulation under eual mode

is shown in figure below

Page 15


16/22

Fig U conceptual diagram of active and reactive power modulation

and as the circuit is inductive the current does not change instantaneously. )n this mode of

operation, a positive converter voltage produces positive power, which means charging the

coil, and a negative converter voltage produces a negative power and discharges the

inductor. /hen the freuency dip in the power system causes a negative voltage to be

applied to the inductor, power flows from the inductor into the power system, sharing the

sudden load. $he reverse process ta0es place when there is a sudden load re8ection in the

power system. $he increase causes a positive voltage to be impressed on the inductor and

the *#* unit absorbs the e+cess power from the power system.

)n actual practice the inductor current should not be allowed to reach 5ero to prevent the

possibility of discontinuous conduction in the presence of the large disturbances )t is

desirable to set the rated inductor current ) such that the ma+imum allowable energy

absorption euals the ma+imum allowable energy discharge .$his ma0es the *#* eually

effective in damping swings caused by sudden increase as well as decrease in load. $hus, ifthe lower current limit is chosen at @., the upper inductor current limit, based on the eual

energy absorption=discharge criterion becomes 1.U ). /hen the current reaches either of

these limits, the dc voltage has to be brought to 5ero.

3s the inductor has a finite inductance and hence a finite amount of energy stored in it, the

Page 16


17/22

Current in the inductor falls as energy is withdrawn from the coil. $his deviation in the

inductor current is e+pressed as

ISM=$ VSM

R!+S &! 11

Prior to the load disturbance, let the magnitudes of voltage and current are Gsm@ and )sm@

nominal values. $hus the initial power flow into the coil can be e+pressed as

EP*@ ' G*@.)*@ 1:

E P* ' )*@.EG* ( )*@.H.E)*. (E G*..E )* 1

)n response to the load disturbance the incremental change of power flow into the coil canbe e+pressed as following a sudden increase in load in the power system, the incremental

power e+pressed by euation is discharged into the power system by the energy storage unit

to share with the generator rotor, the e+tra load demand.

Integration of SMES $ith t$o%area po$er system

Figure shows the proposed configuration of *#* units in a two-area power system. $wo

areas are connected by a wea0 tie-line. /hen there is sudden rise in power demand in a

control area, stored energy is almost immediately released by the *#* through its power

conversion system PC*. 3s the governor control mechanism starts wor0ing to set the

power system to the new condition, the *#* coil stores energy bac0 to its nominal level.

*imilar action happens when there is a sudden decrease in load demand. 4asically, the

operation speed of governor-turbine system is slow compared with that of the e+citation

system. 3s a result, fluctuations in terminal voltage can be corrected by the e+citation

system very uic0ly, but fluctuations in generated power or freuency are corrected slowly.

*ince load freuency control is primarily concerned with the real power=freuency behavior,

the e+citation system model will not be reuired in the appro+imated analysis .$his

important simplification

Page 17


18/22

Configuration of *#* in a two-area power system

Fig N Configuration of *#* in a two-area power system

$he basic ob8ective of the supplementary control is to restore balance between each

areaload and generation for a load disturbance. $his is met when the control action

maintains the freuency and the tie-line power interchange at the scheduled values. $he

supplementary controller with integral gain K is therefore made to act on area control error

3C#, which is a signal obtained from tie-line power flow deviation added to freuency

Page 18


19/22

8'1 where the suffi+ i refer to the control area and 8 refer to the number of generator. 3ll

parameters are same as those used in where the suffi+ i refer to the control area and 8 refer to

the number of generator.

'CEi=

(=1

n

$ Pti )i (

+*i$ %

i 1D

ptimi'ation of integral gain( ):

Figure below shows the freuency deviations for different values of K for a specific load

change. )t is observed that a higher value of K) results in reduction of ma+imum deviation of

the supplementary control results in reduction of ma+imum deviation of the V: system

freuency but the system oscillates for longer times. 6ecreasing the value of K yields

comparatively higher ma+imum freuency deviation at the beginning but provides very

good damping in the later cycles. $hese initiate a variable K, which can be determined from

the freuency error and its derivative. ?bviously, higher values of K ) and freuency bias

factors, V is needed at the initial stage and then it should be changed gradually depending on

the system freuency changes.

Page 19


20/22

Fig N freuency deviations for different values of K for a specific load

Page 20


21/22

C*C+L+SI*:

$he chapter discussed about the simulation studies that have been carried out on a two-

area power system to investigate the impact of the proposed intelligently controlled *#*

on the improvement of power system dynamic performances. $he results clearly show that

the scheme is very powerful in reducing the freuency and tie-power deviations under a

variety of load perturbations. ?n-line adaptation of supplementary controller gain associated

with *#* ma0es the proposed intelligent controllers more effective and are e+pected to

perform optimally under different operating conditions. $he results clearly show that the

scheme is very powerful in reducing the freuency and tie-power deviations under a variety

of load perturbations. ?n-line adaptation of supplementary controller gain associated with

*#* ma0es the proposed intelligent controllers more effective.

Page 21


22/22

References

1. ufti, . >.7 3hmad Hone, *.7 *hei0h, ;. ). W )mran, . :@@O. )mproved Hoad Freuency

Control with *uperconducting agnetic #nergy *torage in )nterconnected Power *ystem,

*EE) ransa!tions on Power an Energy, Gol. :, pp. UO-NO.

:. Banda, ;.7 angla, 3 W *uri, *. :@@M. *ome Bew Findings on 3utomatic !eneration. ?. 1. #lgerd,Ele!tri! Energy ystem #eory- n *ntrou!tion, c!raw 2ill, Bew Qor0,.

D. 3. . 4ergen,Power ystem nalysis, Prentice 2all, #nglewood Cliffs, B. ;., 1NUM.

A. #dward /ilson Kimbar0 )### 9P#**/. odern Power *ystems Control and ?peration by 3tif s. 6ebs Georgia o$ e!#nology

O. /u, C. ;. W Hee, Q. *. 1NN1. 3pplication of *uperconducting agnetic #nergy *torage to

U. )mprove the 6amping of *ynchronous !enerator,*EEE ransa!tions on Energy 0onversion,

Gol. M, Bo. D, pp. AO-AOU, 6ecember 1NN1.

N. 4aner8ee, *.7 Chatter8ee, ;. K. W $ripathy, *. C. 1NN@. 3pplication of agnetic #nergy

*torage >nit as Hoad Freuency *tabili5er,

1@.*EEE ransa!tions on Energy 0onversion, Gol. A, Bo. 1, pp. DM-A1, arch [email protected]. 4en8amin, BB. W Chan, /C. 1NOU. ultilevel Hoad-freuency Control of )nter-Connected

1:. Power *ystems,*EE Pro!eeings, Generation, ransmission an Distri&ution , Gol. Bo.1:A,

pp.A:1A:M.

zahids presentation (2)

Documents