Upload
sarala-kumari
View
216
Download
0
Embed Size (px)
Citation preview
8/19/2019 Chapter Content Final
1/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
CHAPTER 1
INTRODUCTION
GENERAL
In the year 2012, 44.8 GW of new wind energy conversion systems were
installed worldwide. The trend has been toward increasingly larger trbine si!es,
clminating in the installation of off"shore wind #ar$s that are located far from the
load centers . This can lead to rather large distances between generation and load in
the electricity sector. The trans#ortation sector reveals an even larger disconnect
between the locations of fel #rodction and consm#tion. The energy system
#ro#osed in this #a#er see$s to address both isses related to electricity and
trans#ortation sectors. %ne #otential soltion is a microgrid that can be vertically
integrated with a high"rise bilding as fre&ently encontered in rban areas. The
harvesting of renewable wind and solar energy occrs at the to# of the bilding.
There of to# generation connects to the grond level via a microgrid where
electric vehicle '()* charging stations are s##lied, and a battery s##orts
maintaining the balance of s##ly and demand. The #otential vale of an rbanintegration within bildings as considered here comes from the sage of roofto#
energy resorces, the storage of the latter for offering () fast charging at the grond
level, the contribtion to emission"free () trans#ortation in rban areas, the co"
location and integration of generation and load in rban areas, and the grid"friendly
integration of the microgrid with the rest of the #ower system main grid
SCOPE OF THE PROJECT
The combination of wind and solar energy resorces on a roofto# was also
investigated in. It was veri+ed that the combination of wind and solar energy leads to
redced local storage re&irements. The combination of diverse bt com#lementary
storage technologies in trn can form a mltilevel energy storage, where a
s#erca#acitor or ywheel #rovides cache control to com#ensate for fast #ower
ctations and to smoothen the transients encontered by a battery with higher
energy ca#acity. -icrogrids or hybrid energy systems have been shown to be an
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 1
8/19/2019 Chapter Content Final
2/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
effective strctre for local interconnection of distribted renewable generation, loads,
and storage
1.3 EXISTING SYSTEM
arge"scale se of wind #ower raises many &estions in integration into the e5isting
electric #ower grid. Wind #ower is an intermittent energy sorce which mst be sed
when available. If a large fraction of a system6s energy is to come from wind #ower,
#rovisions mst be made to s##ly load dring days with low wind. These #rovisions
might ta$e the form of s#inning reserve already allocated in the system, start"# of
stand"by #ower #lants, or interconnections to other areas that can ta$e # the load.
1.4 EXISTING SYSTEMS TECHNIQUE
ecase grid o#erational strategies are designed for traditional dis#atch able energy
sorces li$e coal, integrating wind energy into the tility grid can be #roblematic.
Within the #ower grid, there mst be balance between load and generation, economic
and #olicy incentives, cost"effective storage, and robst and distribted control.
1.5 LITERATURE SURVEY
(5#lains 7hotovoltaic ystems '7)* can be easily integrated in residential
bildings hence they will be the main res#onsible of ma$ing low"voltage grid #ower
flow bidirectional. ontrol isses on both the 7) side and on the grid side have
received mch attention from manfactrers, com#eting for efficiency and low
distortion and academia #ro#osing new ideas soon become state"of"the art. This
#ro9ect aims at reviewing #art of these to#ics '-77T, crrent and voltage control*
leaving to a ftre #a#er to com#lete the scenario.7resents the develo#ment of
renewable energy sorces is becoming more and more attractive. This #a#er first
reviews both the wind #ower and #hotovoltaic '7)* #ower generation techni&es and
their ma5imm"#ower"#oint trac$ing '-77T* methods. Then, a new stand"alone
wind:7) hybrid generation system is #ro#osed for a##lication to remote and isolated
areas. ;or the wind #ower generation branch, a new dobly e5cited #ermanent"
magnet brshless machine is sed to ca#tre the ma5imm wind #ower by sing
online fl5 control. ;or the 7) #ower generation branch, a single"ended #rimary
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 2
8/19/2019 Chapter Content Final
3/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
indctance converter is ado#ted to harness the ma5imm solar #ower by tning the
dty cycle.
7resents 7ower electronic Grid"onnected onverters 'Gs* are widely
a##lied as grid interface in renewable energy sorces this #a#er #ro#oses an e5tended
8/19/2019 Chapter Content Final
4/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
1. PROPOSED SYSTEM
ecent research has considered the o#timi!ation of the o#eration on one hand and the
sage of dc to lin$ the resorces on the other. The dc lin$ voltage was shown to be
maintained by a droo# control that relates the dc lin$ voltage to the #ower ot#t of
controllable resorces. In this #a#er, it is #ro#osed to set the droo# as a fnction of the
e5#ected state of charge '%* of the battery according to its o#erational o#timi!ation
set #oint verss the actal realtime %.
The #ro#osed o#erational o#timi!ation is frther distingished in that it &anti+es the
ncertainty associated with renewable generation forecast, emission constraints, and
() fast charging. ;ollowing this introdction, an otline of the #rinci#le of a dc
microgrid is given in ection II. In ection III, a method is develo#ed for &antifying
the aggregated wind and solar #ower forecast ncertainty, the reslting re&ired %
of the battery, and the o#erational o#timi!ation.
1.! PROPOSED SYSTEM TECHNIQUES
> voltage sorce converter ')*"based T%- is connected to a three
#hase ac mains feeding three #hase linear?nonlinear loads with internal grid
im#edance which is shown in ;ig. The #erformance of T%- de#ends #on
the accracy of harmonic crrent detection. ;or redcing ri##le in com#ensating
crrents, the tned vales of interfacing indctors '* are connected at the ac ot#t
of the ). > three #hase series combination of ca#acitor 'f * and a resistor 'ff*
re#resents the shnt #assive ri##le +lter which is con" nected at a #oint of common
co#ling '7* for redcing the high fre&ency switching noise of the ). The
T%- crrents 'i abc* are in9ected as re&ired com#ensating crrents to
cancel the reactive #ower com#onents and harmonics of the load crrents so that
loading de to reactive #ower com#onent? harmonics is redced on the distribtion
system. ;or the considered three #hase nonlinear load with a##ro5imately 24 @w
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 4
8/19/2019 Chapter Content Final
5/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
1." ADVANTAGES OF PROPOSED SYSTEM
The real"time o#eration of the microgrid in the interconnected and atonomos
modes is stdied. In the interconnected mode of o#eration, an ada#tive droo# control
is devised for the (. The ada#tive droo# characteristic of the ( #ower
electronic converter is selected on the basis of the deviation between the o#timi!ed
and real"time % of the (, as calclated in ection III.
8/19/2019 Chapter Content Final
6/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
CHAPTER $
PROJECT DESCRIPTION
$.1 GENERAL
> wind trbine or wind #ower #lant is a device that converts $inetic energy
from the wind into electrical #ower. > wind trbine sed for charging batteries may be
referred to as a wind charger the reslt of over a millennim of windmill develo#ment
and modern engineering, today6s wind trbines are manfactred in a wide range of
vertical and hori!ontal a5is ty#es.The smallest trbines are sed for a##lications sch
as battery charging for a5iliary #ower for boats or caravans or to #ower traffic
warning signs. lightly larger trbines can be sed for ma$ing small contribtions to a
domestic #ower s##ly whilst selling nsed #ower bac$ to the tility s##lier via the
electrical grid.
>rrays of large trbines, $nown as wind farms, are becoming an increasingly
im#ortant sorce of renewable energy and are sed by many contries as #art of a
strategy to redce their reliance on fossil fels.Wind trbines, also called windmills,
harness the #ower of the wind to #rodce electricity. When sed commercially, gro#s
of wind trbines are erected to form a wind farm ca#able of #owering entire
neighborhoods. The amont of energy generated de#ends on the si!e of the wind
trbine and the wind s#eed in the area.
$.$ MODULES NAME
• Wind 7ower
•
tand >lone Generators
• 7ermanent -agnet ynchronos Generator '7-G*
• > to
8/19/2019 Chapter Content Final
7/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
$.3 MODULE DESCRIPTION
W%&' P()*+
The global ado#tion of wind energy as a reliable sorce for clean energy isrising. It has become more im#ortant for com#onent manfactrers and trbine
integrators to increase com#onent #rodction rate, im#rove system reliability, and
overcome grid integration challenges to im#lement faster ado#tion of wind energy
and ltimately global inde#endence from oil" and coal"based energy sorces. > shift
toward im#roved technology for atomated com#onent testing, online condition
monitoring, and grid integration control can hel# solve these challenges.
S,-&' A(&* G*&*+-,(+/
If yo have a large hose or a large family, and wish to #ower as mch as yo
can in a blac$ot, yo will want a standalone nit. (ven this will #robably not #ower
yor whole hose, bt certainly a lot more than most #ortable nits. t they can be
e5#ensive and re&ire s#ace to be installed. They can be &ite large. If yo live in an
area that gets a lot of wild weather, from rain and hail, to snow and ice, then yo will
en9oy the l5ry of a standalone generator.
(ven if yo choose a standalone nit, it always #ays to have a #ortable on hand as
well. Cst becase yo live an area that has mild weather, yo never $now when the
#ower will go down. (arth&a$es as well as rolling blac$ots and brownots are a
#ossibility. #ermanent magnet synchronos generator is a generator where the
e5citation field is #rovided by a #ermanent magnet instead of a coil. ynchronos
generators are the ma9ority sorce of commercial electrical energy. They are
commonly sed to convert the mechanical #ower ot#t of steam trbines, gas
trbines, reci#rocating engines, hydro trbines and wind trbines into electrical #ower
for the grid.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 7
8/19/2019 Chapter Content Final
8/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
They are $nown as synchronos generators becase f, the fre&ency of the indced
voltage in the rotor 'armatre condctors*, is directly #ro#ortional to 7, the nmber of
#ermanent magnet stator #oles 'almost always an even nmber*. The constant of
#ro#ortionality is, where 7- is the revoltions #er minte of the rotor 'or anglar s#eed* in a #ermanent magnet generator, the magnetic field of the rotor is #rodced by
#ermanent magnets.%ther ty#es of generator se electromagnets to #rodce a
magnetic field in a rotor winding. The direct crrent in the rotor field winding is fed
throgh a sli#"ring assembly or #rovided by a brshless e5citer on the same shaft.
7ermanent magnet generators do not re&ire a #ersistent
magnetic field im#oses safety isses dring assembly, field service or re#air. /igh
#erformance #ermanent magnets, themselves, have strctral and thermal isses.
Tor&e crrent --; vertically combines with the #ersistent fl5 of #ermanent
magnets, which leads to higher air"ga# fl5 density and eventally, core satration. In
these #ermanent magnet alternators the s#eed is directly #ro#ortional to the ot#t
voltage of the alternator.
AC ,( DC C(&8*+/%(&
The tas$ of trning alternating crrent into direct crrent is
called rectification, and the electronic circit that does the 9ob is called a rectifier. The
most common way to convert alternating crrent into direct crrent is to se one or
more diodes, those handy electronic com#onents that allow crrent to #ass in onedirection bt not the other.
>lthogh a rectifier converts alternating crrent to direct crrent, the reslting
direct crrent isn6t a steady voltage. It wold be more accrate to refer to it as
D#lsating lthogh the #lsating voltage thatFs fed into the rectifier.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 8
8/19/2019 Chapter Content Final
9/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;or many
8/19/2019 Chapter Content Final
10/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
Grid energy storage a##lications se rechargeable batteries for load leveling, where
they store electric energy for se dring #ea$ load #eriods, and for renewable energy
ses, sch as storing #ower generated from wind based 7-G dring the normal
s#eed to be sed at low s#eed condition. y charging batteries dring #eriods of lowdemand and retrning energy to the grid dring #eriods of high electrical demand,
load"leveling hel#s eliminate the need for e5#ensive #ea$ing #ower #lants and hel#s
amorti!e the cost of generators over more hors of o#eration.
$.4 P+(9(/*' /%&* 9-/* /,-&' -(&* )%&' ,+:%&* 0('*
;
ig.2.4#ro#osed single #hase standalone wind genarator model
;ig .2.2 simlation design of wind based 7-G
The #ro#osed stand"alone wind #ower system s##lies single"#hase
consmers at 20 )?H0 /!. It is designed for a residential location, and it is based on
a 2"$W wind trbine ';ig. 2.1*, e&i##ed with the following=
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 10
8/19/2019 Chapter Content Final
11/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
1* > direct"driven 7-G
2* >n ac?dc converter 'diode rectifier bridge B boost converter* for the trac$ing of the
ma5imm #ower from the available wind resorce
* > > storage device
4* >n inverter
H* > transformer
J* esistive loads.
The wind #ower is converted into the mechanical rotational energy of the wind
trbine rotor. > wind trbine cannot Dcom#letelyE e5tract the #ower from the wind.
Theoretically, only HKL of the wind #ower cold be tili!ed by a wind trbine, bt for
the 2"$W wind trbine system analy!ed in this #a#er, the real #ower coefficient is
KL.The wind trbine rotor is connected to the wind generator, ths converting the
mechanical energy into electrical energy. The generatorFs ac voltage is converted into
dc voltage throgh an ac?dc converter. The rectifier is matching the generatorFs ac
voltage to the dc voltage, while the boost converter #rovides the re&ired level of
constant dc voltage. The dc ot#t voltage is fed to the battery ban$ and throgh an
inverter frther to the load.
The voltage shold stay constant for varios wind s#eeds. When the wind
s#eed is too high, the #ower e5cess s##lied by the wind trbine is stored in the
battery. When the wind s#eed is low, the generator, together with the battery ban$, can
#rovide sfficient energy to the loads.The dc loads are s##lied directly from the dc
circit. >t high s#eeds, the trbine control system sto#s the energy #rodction. The
same #rotection is activated also in the case when the battery is flly charged and
energy #rodction e5ceeds consm#tion.
>t low wind s#eeds, load shedding is sed to $ee# the fre&ency at the rated
vale. The storage system is com#osed of a > and a fll"bridge single"#hase
inverter that converts the dc voltage of the battery to ac voltage. ;rthermore, this
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 11
8/19/2019 Chapter Content Final
12/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
voltage is a##lied to a single #hase transformer, which boosts # the voltage to 20 ).
The inverter controls the #ower transfer.
SUPER CAPACITOR
#er ca#acitors merged with batteries 'hybrid battery* will become the new
s#er battery. Cst abot everything that is now #owered by batteries will be im#roved
by this mch better energy s##ly. They can be made in most any si!e, from #ostage
stam# to hybrid car battery #ac$. Their light weight and low cost ma$e them attractive
for most #ortable electronics and #hones, as well as aircraft and atomobiles.
The new ones are fle5ible and biodegradable and can be #owered by body flids.
'ince body flids can act as an electrolyte, the battery can be sed for medical
devices and cold be installed into a #atient flly charged bt dry and feed off bodily
flids to allow it to re"#ower and discharge energy. The ftre of the battery is here.
)irtally nlimited life cycle " cycles millions of time "10 to 12 year life
ow im#edance
harges in seconds
o danger of overcharge
)ery high rates of charge and discharge
/igh cycle efficiency 'KHL or more*
#er ca#acitors and ltra ca#acitors are relatively e5#ensive in terms of cost #er watt
#erca#acitors or 3ltra a#acitors were initially sed by the 3 military to start the
engines of tan$s and sbmarines. -ost a##lications now are in small a##liances,
handheld electronics and hybrid electric vehicles.
>> has a research #ro9ect to se s#erca#acitors in an electric bs called
the /ybrid (lectric Transit s. The energy sed to start the engine and accelerate the
bs is regenerated from bra$ing.
8/19/2019 Chapter Content Final
13/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
s#erca#acitors, each of them weighing 2 $g and releasing energy of H0 $C at 200 )
managed to rn for for miles.
In most hybrid vehicles, 42 ) s#er ca#acitors are sed. General -otors has
develo#ed a #ic$# trc$ with a )8 engine that ses the s#erca#acitor ? ltra
ca#acitor to re#lace the battery. The efficiency of the engine rose by 14L. The
s#erca#acitor s##lies energy to the alternator. Toyota has develo#ed a diesel engine
sing the same technology and it is claimed to se 9st 2.M liters of fel #er 100 $m.
PHOTOVOLTAIC CELLS AND ARRAY R ESEARCH
7hotovoltaic cells are devices that absorb snlight and convert that solar
energy into electrical energy. olar cells are commonly made of silicon, one of the
most abndant elements on (arth. 7re silicon, an actal #oor condctor of electricity,
has for oter valence electrons that form tetrahedral crystal lattices.
The electron clods of the crystalline sheets are stressed by adding trace amonts of
elements that have three or five oter shell electrons that will enable electrons to
move. The nclei of these elements fit well in the crystal lattice, bt with only three
oter shell electrons, there are too few electrons to balance ot, and N#ositive holesN
float in the electron clod. With five oter shell electrons, there are too many
electrons. The #rocess of adding these im#rities on #r#ose is called Ndo#ing.N When
do#ed with an element with five electrons, the reslting silicon is called "ty#e 'NnN
for negative* becase of the #revalence of free electrons. i$ewise, when do#ed with
an element of three electrons, the silicon is called 7"ty#e. The absence of electrons
'the NholesN* define 7"ty#e.
The combination of "ty#e and 7"ty#e silicon case an electrostatic field to
form at the 9nction. >t the 9nction, electrons from the sides mi5 and form a barrier,
ma$ing it hard for electrons on the side to cross to the 7 side. (ventally
e&ilibrim is reached, and an electric field se#arates the sides. When #hotons
'snlight* hit a solar cell, its energy frees electron"holes #airs. The electric field will
send the free electron to the side and hole to the 7 side. This cases frther
disr#tion of electrical netrality, and if an e5ternal crrent #ath is #rovided, electrons
will flow throgh the #ath to their original side 'the 7 side* to nite with holes that the
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 13
8/19/2019 Chapter Content Final
14/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
electric field sent there, doing wor$ for s along the way. The electron flow #rovides
the crrent, and the cell6s electric field cases a voltage. With both crrent and
voltage, we have #ower, which is the #rodct of the two. Three solar cell ty#es are
crrently available= monocrystalline, #olycrystalline, and thin film, discerned bymaterial, efficiency, and com#osition. y wiring solar cells in series, the voltage can
be increased or in #arallel, the crrent. olar cells are wired together to form a solar
#anel. olar #anels can be 9oined to create a solar array.
MODULES NAME
• 7) >rray
• -77T
• 7W-
• onversion
• oost onverter
MODULE DESCRIPTION
PV A++-2
The (lectrical (ngineering
8/19/2019 Chapter Content Final
15/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
The amont of sefl snshine available for the #anels on an average day
dring the worst month of the year is called the Dinsolation valeN. The worst month is
sed for analysis to ensre the system will o#erate year"rond. In >ssit, average solar
insolation is J.0 hors #er day in
8/19/2019 Chapter Content Final
16/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
shnt resistance of the cell 'in ;ig. *
q
is the electronic charge sc I
is the light"
generated crrent Io is the reverse atration crrent K
is the olt!man constant,
andk
T
is the tem#eratre in K
.
(&ation '1* can be written in another form as PMQ
shs1 *?'"QO1P1R2 R IRV e K I I
mV K
sc +−−=
'2*
where the coefficient1 K ,
2 K and m are defined as
,011MH.01 = K
,*?'42m
ocV K K =
*?*1ln'' 114 K K K +=
,
Q,?**1'lnP'11G scmpp sc
I K I K I K −+=
*?ln'?*?ln' 4G ocmpp V V K K m =
I mpp is the crrent at ma5imm ot#t #ower,
mppV
is the voltage at ma5imm #ower,
sc I
is the short circit crrent andocV
is the o#en circit voltage of the array.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 16
8/19/2019 Chapter Content Final
17/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;ig. 2. (&ivalent circit of 7) array.
;ig. 2.4 )"I and 7"I characteristics at constant tem#eratre.
(&ation '2* is only a##licable at one #articlar o#erating condition of illmination G
and cell tem#eratrecT
.The #arameter variations can be calclated by measring the
variation of the short"circit crrent and the o#en"circit voltage in these conditions
sing the #arameters at the normal illmination and cell tem#eratre. (&ation '2* is
sed for the I-V and P-V characteristics for varios illmination and fi5ed tem#eratre
'QP2H C o
* in ;ig. 2.4.
arrier ased 7W- Techni&es
There are many variations of carrier based 7W-.
• >nalog vs. digital
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 17
8/19/2019 Chapter Content Final
18/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
• ine"triangle vs. s#ace vector 'in reality very similar*
• Trianglar vs. saw tooth carrier
• ymmetric vs. asymmetric 'sam#led once?twice #er triangle*
• 3niform sam#ling vs. natral sam#ling
• 7eriodic vs. a#eriodic carrier.
;or the #r#oses of defining this broad category, carrier based 7W- methods are
those where the switching decisions of the inverter are made for each switching cycle
either at the beginning or dring that switch cycle. That is, the 7W- waveform iscalclated on a cycle by cycle basis, either #lse by #lse, or edge by edge. This
distingishes it from /( and /- 7W-, where mlti#le switching edges are
ma##ed ot for the entire fndamental #eriod or some fraction therein and hysteresis
7W-, where neither edges nor switch #eriod are defined, calclated or even $nown
in advance. > com#arison of waveforms and fre&ency s#ectra of three different
7W- strategies are shown in ;ig below.
;ndamental f
arrier f
ine"sawtooth 7W-
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 18
8/19/2019 Chapter Content Final
19/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
ine"triangle 7W-
/armonic elimination 7W-
/ysteresis 7W-
;rom the to#, wave forms and fre&ency s#ectra of the original sinsoidal
modlating waveform, the nmodlated 7W- s&are wave, sine"saw tooth 'single
edge carrier* 7W-, sine"triangle 'doble edge carrier* 7W-, elective /armonic
(limination '/(* 7W- and /ysteresis 7W-.
The two basic a##roaches sed to generate the 7W- signals for mltilevel inverters
are=b harmonic or b"%scillation carrier based 7W-"modlating waveform
com#arison with offset trianglar carriers.
#ace )ector 7W-"s#ace vector modlation based on a rotating vector in mltilevel
s#ace.These are the e5tensions of traditional two level control strategies to several
levels. The two main advantages of 7W- inverters in com#arison to s&are"wave
inverters are
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 19
8/19/2019 Chapter Content Final
20/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
'i* control over ot#t voltage magnitde
'ii* edction in magnitdes of nwanted harmonic voltages.
Good &ality ot#t voltage in 7W- re&ires the modlation inde5 'm* to be lessthan or e&al to 1.0. ;or mS1 'over"modlation*, the fndamental voltage magnitde
increases bt at the cost of decreased &ality of ot#t waveform. The ma5imm
fndamental voltage that the 7W- inverter can ot#t 'withot resorting to over"
modlation* is only M8.HL of the fndamental voltage ot#t by s&are"wave inverter.
The merits and demerits of these two 7W- techni&es are com#ared nder
com#arable circit conditions on the basis of factors li$e 'i* &ality of ot#t voltage
'ii* obtainable magnitde of ot#t voltage 'iii* ease of control etc. The #ea$
obtainable ot#t voltage from the given in#t dc voltage is one im#ortant figre of
merit for the inverter.arriers considered different methods of dis#osing the many
carrier bands re&ired in mltilevel 7W-.
;or alternative carrier 7W- strategies with differing #hase relationshi#s for a
mltilevel inverter are as follows=
1* In"#hase dis#osition 'I72
* >lternative #hase o##osition dis#osition '>7%
8/19/2019 Chapter Content Final
21/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
ingle #hase ncontrolled rectifiers are e5tensively sed in a nmber of #ower
electronic based converters. In most cases they are sed to #rovide an intermediate
nreglated dc voltage sorce which is frther #rocessed to obtain a reglated dc or ac
ot#t. They have, in general, been #roved to be efficient and robst #ower stages./owever, they sffer from a few disadvantages. The main among them is their
inability to control the ot#t dc voltage ? crrent magnitde when the in#t ac
voltage and load #arameters remain fi5ed. They are also nidirectional in the sense
that they allow electrical #ower to flow from the ac side to the dc side only. These two
disadvantages are the direct conse&ences of sing #ower diodes in these converters
which can bloc$ voltage only in one direction. >s will be shown in this modle, these
two disadvantages are overcome if the diodes are re#laced by thyristors, the reslting
converters are called flly controlled converters.
Thyristors are semi controlled devices which can be trned % by a##lying a
crrent #lse at its gate terminal at a desired instance. /owever, they cannot be trned
off from the gate terminals. Therefore, the flly controlled converter contines to
e5hibit load de#endent ot#t voltage ? crrent waveforms as in the case of their
ncontrolled conter#art. /owever, since the thyristor can bloc$ forward voltage, the
ot#t voltage ? crrent magnitde can be controlled by controlling the trn on
instants of the thyristors. Wor$ing #rinci#le of thyristors based single #hase flly
controlled converters will be e5#lained first in the case of a single thyristor half wave
rectifier circit s##lying an or " load. /owever, sch converters are rarely sed
in #ractice.
;ll bridge is the most #o#lar configration sed with single #hase flly
controlled rectifiers. >nalysis and #erformance of this rectifier s##lying an ""(
load 'which may re#resent a dc motor* will be stdied in detail in this lesson.
S%&* 9-/*
8/19/2019 Chapter Content Final
22/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;ig.2.J. shows the circit diagram of a single #hase flly controlled halfwave rectifier s##lying a #rely resistive load.
>t t U 0 when the in#t s##ly voltage becomes #ositive the thyristor T becomes
forward biased. /owever, nli$e a diode, it does not trn % till a gate #lse is
a##lied at t U V.
8/19/2019 Chapter Content Final
23/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
imilar calclation can be done for i0. In #articlars for #re resistive loads ;;io U
;;vo.
R*/%/,%8*=I&',%8* (-'
;ig 10.2 'a* and 'b* shows the circit diagram and the waveforms of a single #hase
flly controlled half wave rectifier s##lying a resistive indctive load. >lthogh this
circit is hardly sed in #ractice its analysis does #rovide sefl insight into the
o#eration of flly controlled rectifiers which will hel# to a##reciate the o#eration of
single #hase bridge converters to be discssed later.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 23
8/19/2019 Chapter Content Final
24/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
>s in the case of a resistive load, the thyristor T becomes forward biased
when the s##ly voltage becomes #ositive at t U 0. /owever, it does not start
condction ntil a gate #lse is a##lied at t U V. >s the thyristor trns % at t U V
the in#t voltage a##ears across the load and the load crrent starts bilding #.
/owever, nli$e a resistive load, the load crrent does not become !ero at t U Y,
instead it contines to flow throgh the thyristor and the negative s##ly voltage
a##ears across the load forcing the load crrent to decrease. ;inally, at t U Z 'Z S Y*
the load crrent becomes !ero and the thyristor ndergoes reverse recovery. ;rom this
#oint onwards the thyristor starts bloc$ing the s##ly voltage and the load voltage
remains !ero ntil the thyristor is trned % again in the ne5t cycle. It is to be noted
that the vale of Z de#ends on the load #arameters.
Therefore, nli$e the resistive load the average and - ot#t voltage de#ends on
the load #arameters. ince the thyristors does not condct over the entire in#t s##ly
cycle this mode of o#eration is called the Ddiscontinos condction modeE.
;rom above discssion one can write.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 24
8/19/2019 Chapter Content Final
25/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
ince the average voltage dro# across the indctor is !ero.
/owever, I%- cannot be obtained from )%- directly. ;or that a closed from
e5#ression for i0 will be re&ired. The vale of Z in terms of the circit #arameters can
also be fond from the e5#ression of i0.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 25
8/19/2019 Chapter Content Final
26/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
The general soltion of which is given by
(&ation '10.1* can be sed to find ot I%-. To find ot Z it is noted that
(&ation '10.14* can be solved to find ot Z
W%&' S2/,*0
Wind is a highly stochastic energy sorce. There is also a strong
interde#endence between the aerodynamic characteristics of the wind trbine, the
generatorFs rotor s#eed, and the amont of #ower that can be e5tracted from the wind.
/ence, it becomes necessary to im#lement a control method that will enable the
e5traction of the ma5imm #ower from the system nder all #ossible o#eratingconditions. The following sections highlight the ma9or com#onents of a stand"alone
W(
G*&*+- 0('*%& (< )%&' ,+:%&*
Wind trbines are classified based on the nmber of blades and the a5is abot which
they are monted. Ty#ically, the three blade hori!ontal"a5is wind trbine is #referred
de to better #erformance as well as the even distribtion of variations in ind s#eed
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 26
8/19/2019 Chapter Content Final
27/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
from the rotors to the drive shaft. It is also ca#able of achieving better #ower
coefficient
The ot#t mechanical #ower of the wind trbine is given by the cbe law e&ation
where ρ is the density of air 'in $g · m*, Cp is the #ower coefficient, A is the area
swe#t by the wind trbine rotor 'in
s&are meter*, Uw is the wind s#eed 'in meters #er second*. The #ower coefficient is a
fnction of the ti# s#eed ratio λ and the blade #itch angle β . It describes the efficiencyof the wind trbine in converting the energy #resent in wind into mechanical #ower.
The ti# s#eed ratio λ may be defined as the ratio of the s#eed at which the oter ti# of
the trbine blade is moving to the wind s#eed. It is given by the e&ation
The blade #itch angle β is defined as the angle at which the wind contacts the bladesrface. The e5#ression for #ower coefficient is given as
It is valid to assme #itch angle to be !ero for low to medim wind velocities PKQ.
/ence, in this wor$, β U 0◦. To achieve ma5imm e5traction of #ower from the
system, the ti# s#eed ratio and #ower coefficient have to be maintained close to the
o#timal vales and varied according to the variations in the wind s#eed conditions.
The mechanical tor&e of the system is given by the e&ation
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 27
8/19/2019 Chapter Content Final
28/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
Tm U 7m?m ' [ m*. 'H*
C(&WT* and )>WT .
The role of a wind energy system is to ca#tre mechanical energy in the air ow and
convert it to electrical energy. 3sally it consists of a wind trbine rotor, for the
former #r#ose, and an electrical machine wor$ing as generator for the latter. The
variation in the wind s#eed is one of the factors that aff ects the s#eci+cations of wind
energy systems. In other words design of the wind systemsF com#onents demands
s#ecial consideration. The amont of accessible mechanical energy de#ends on the
si!e of the wind trbine and the wind regime of the site.
$.1 W%&' T+:%&* A*+('2&-0%/
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 28
8/19/2019 Chapter Content Final
29/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
The amont of the $inetic energy in the air ow can be determined based on
the si!e of wind trbine and the wind s#eed. The elementary momentm theory gives
an e5#laination of energy conversion in ideal circmstances. The amont of the
$inetic energy of a id mass \ m with a mass density ] , moving at a velocity ϑthrogh the area > is
and the mass ow is
The #ower available in the wind is e&al to the amont of energy yield #assing #er
second.
It is obvios that a small variation in the wind s#eed inences the available wind
#ower drastically. It was +rst in 1K22, the German engineer et! showed that
;igre 2.H. 7ower coefficient verss ti# s#eed ratioQ.
the amont of e5tractable energy from an air stream is limited. It was shown that, in a
free air stream, the ma5imm energy is e5tracted if the wind s#eed is redced by three
times far behind the trbine in com#arison to in front of it. The ma5imm e5tractable
#ower becomes then, 1J?2M of available wind #ower.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 29
8/19/2019 Chapter Content Final
30/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;or steady state analysis of aerodynamic conversion, a #ower coefficient diagram is
sed. >s mentioned, it is not #ossible to ca#tre all the #ower in the air ow as this
wold reslt in air standstill immediately after the wind trbine. >erodynamic
efficiency re#resents a ratio of ca#tred #ower and available wind #ower. In wind #ower terminology, it is more $nown as the #ower coefficient. et! factor is the
ma5imm vale for the #ower coefficient.
The #ower coefficient # is a fnction of the ti# s#eed ratio ^ and the blade #itch
angle Z. (&ation 2. above, is modi+ed according to e&ation 2.4.
where
is the rotor ti# anglar s#eed and r is the rotor #lane radis. lade #itching means
that the rotor blades are rotated along their a5is, in order to control the amont of the
absorbed #ower. In wind trbines which are not e&i##ed with the control of the
blade #itch, #ower coefficient is merely fnction of the ti# s#eed ratio. ;igre 2.H
shows a ty#ical #ower coefficient diagram. 7ower coefficient is ma5imm at the
o#timm ti# s#eed ratio i.e. in order to ca#tre the ma5imm energy, the wind trbine
rotor has to be rn at this ratio. When the wind trbine rotor is rn at other ti# s#eed
ratios, eddies will develo# at the blade ti#. This #henomenon redces the ca#tred
energy and it is called stall. It e5#lains the dro# of the #ower coe fficient at other ti#
s#eed ratios.
It can be observed from the #ower coefficient diagram in ;igre 2.H, that the wind
trbine is not self starting. ;or low vales of the ti# s#eed ratio, the vale of the #ower
coefficient is negative. -any lift based wind trbines re&ire a minimm ti# s#eed
ratio before they can start to absorb the #ower . >ccordingly, in order to start # the
wind trbine rotor, energy has to be s##lied. There are diff erent ways to do so, one is
to tilise an a5iliary self starting trbine li$e for e5am#le avonios wind trbine.
>nother is certain modi+cation in the design of the wind trbine. ;rthermore,
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 30
8/19/2019 Chapter Content Final
31/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
electrical starting of wind trbine is yet another #ossibility. The generator is, then, fed
by the grid for a short dration of time and wor$s as a motor in order to start the wind
trbine. In this soltion the wind #ower #lant cannot o#erate as a stand alone nit.
$.$ W%&' T+:%&*/
Wind trbines are categorised based on two diff erent criteria ;irst de to their
aerodynamic fnction second based on their design. onsidering the aerodynamic
#erformance, wind trbines are divided into drag based and lift based. The rotors
which tilise the drag force of the wind are recognised a slow s#eed trbines.
/owever ,in some trbines, the #ossibility of em#loying the lift force is also #rovided.
The lift based trbines are recognised as high s#eed rotors. These are ca#able of
ca#tring higher amont of the wind #ower com#ared to their drag based conter#arts
and therefore they are the most common soltion today. WT or )>WT.
/>WTs have bene+ted from technological advancements in the aircraft engineering
becase of the blades F#ro#eller li$e design. ;or instance, to achieve more lift forces,
blade sha#esF o#timisation are #ro#osed and a##lied. 7ower coefficients # to 0.H of />WT s have been re#orted. TodayFs )>WT s have reached #ower coefficient # to
0.4 at ma5imm. ;igre 2.J and ;igre 2.M show a / rotor )>WT and an installed
/>WT res#ectively. im#licity of the design of the )>WT s is bene+cial, es#ecially
the #ossibility to accommodate some of the drive train com#onents on the grond
together with absence of the yaw system 2. ome disadvantages of the system are the
lower o#timm ti# s#eed ratio, inability to self start and inability to im#lement blade
#itching for #ower control #r#oses. In some of the researchersF o#inion the )>WT_ #ower coefficient can e5ceed that of />WT sF .
2.2.1 Wor$ing 7rinci#le of )>WT
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 31
8/19/2019 Chapter Content Final
32/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;igre 2.J shows a hori!ontal #lan of a )>WT . The hb is assmed to be located at
the centre of the coordinate system. The area with a #ositive vale on
;igre 2.J. >n / rotor )>WT .
y"a5is in artesian coordinate system is de+ned as # wind region and there maining
area is de+ned as the downwind region. The angle of attac$ is the relative angle
between the chord line of the blade cross section and the wind direction. This angle,
seen by the blades in the #wind region, is negative. ince the angle of attac$ is
negative, the lift force vectors #rodced on the blade section will #oint inwards the
rotor. The force can be decom#osed into two diff erent com#onents, a tangential and a
normal. The former is along the tangent of the blade and the latter is #er#endiclar to
the blade. -oreover, the lift force will be created in downwind region. /ere the angle
of attac$ is #ositive, the conse&ent lift force vectors will #oint otwards the rotor.
Tangential lift forces, originated from #wind and downwind regions, contribte to
the tor&e #rodction in the rotor. The normal force slead to thrst along the wind
direction
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 32
8/19/2019 Chapter Content Final
33/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;igre 2.M. > 4H0 $w />WT with M m rotor diameter 'ons*.
;igre 2.8. /ori!ontal #lan of a )>WT
$.3 M*-&%- D+%8* T+-%&
The term Nmechanical drive trainNstands for all rotating #arts of the wind
system from the rotor hb to the rotor of the generator. In conventional #ower #lant
technology, two re&irements by mechanical drive are met= ;irst e&ity of in#t
#ower to the generator with the amont of needed #ower by the load econd
matching the s#eed levels of the #rime mover with the s#eed of the generator. In wind
systems, however, mechanical drive train does not meet neither of these re&irements.
The #ower #rodction de#ends on the available wind resorce which is not
controllable. ;rthermore, wind s#eed is far from rated s#eed of the conventional
generators. The drive trains are classi+ed according to im#lementation of a wind
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 33
8/19/2019 Chapter Content Final
34/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
system in order to com#are their characteristics. (ach drive ty#e #ossesses s#eci+c
advantages and disadvantages, sch as aerodynamic and dynamic #erformance,
controllability, reliability, maintenance , etc.
$.3.1 F%>*' S9**' (+ V-+%-:* S9**'
In +5ed s#eed wind systems, the rotor s#eed is determined by the
grid fre&ency and its variation is limited to arond `1L of the nominal s#eed.
3sally, the +5ed s#eed wind systems is designed in sch a way that it has its
o#timm wind s#eed e&al to site mean wind s#eed. o means for #ower control is
a##lied and the advantage is sim#licity of o#eration. nother soltion is to have two windings with
diff erent #ole nmbers in the same generator. In )ariable #eed wind systems, #ower
electronics converters $ee#s the rotor s#eed and the grid fre&ency a#art. Therefore it
is #ossible to vary the rotor s#eed inde#endent of the grid fre&ency. /ence, the
variation in the in#t #ower will reslt in the rotor s#eed variation. The ot#t #ower
from wind system will be slightly lower than the in#t #ower which reslts in morestable and smooth delivered #ower to the grid. The #ower &ality of these wind
energy systems is mch better com#ared to their +5ed s#eed conter#arts.
;rthermore, they have lower noise in low wind conditions . In variable s#eed
systems, the wind trbine is o#erated in a wider s#eed range, $ee#ing the ti# s#eed
ratio at the o#timm. The advantage is higher energy ca#tre, however, the
disadvantage is more com#licated control method.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 34
8/19/2019 Chapter Content Final
35/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
$.3.$ G*-+*' (+ D%+*, D+%8*&
Wind energy systems can be distingished based on whether or not they in"
clde gearbo5es. Wind trbine rotors are ca#able of rotating at tens of rotations #er
minte. /owever, the conventional electrical machines rns at mch higher s#eeds
e.g. hndreds of otation 7er -inte 'r#m* . The role of a gearbo5 is to transfer
mechanical energy from low s#eed to high s#eed > ste# # gearbo5 is sed then.
Im#lementation of a gearbo5 has its own disadvantages, e.g. maintenance, installation
com#lication, cost of e&i#ment, adible noise and losses. The gearbo5 is one of the
reasons for adible noise in wind energy systems. The losses in the gearbo5 are
com#arable to the losses in the electric machine. ewly designed wind systems are
sally ada#ted for gearless o#eration. This soltion has become more reliable, more
efficient and less noisy. The main disadvantage is a need for a s#ecial designed
generator which tends to be bl$y.
lthogh the converters
are sorce of losses, controllability is a hge advantage com#ared to the gearbo5es.
@nowledge abot constrction and o#eration of gearbo5es alleviates their after"
math. Gearbo5esaredividedintotwodiff erentcon+grations7arallelshaftors#r gear
which has a sim#ler mechanical constrction and a gear ratio of # to 1 = H in each
stage 7lanetary or helical gearbo5 which has more com#licated mechanical
constrction and a gear ratio of # to 1 = 12 in each stage. />WT s rn ty#ically at
20r#m and sally re&ires more than one stage. Tooth an$ friction and oil ow are
the origins of #ower losses in the gearbo5es. The average amont of losses de#endson the gear ratio and the ty#e of the gear. It is estimated as a##ro5imately 2L of fll
#ower #er stage for #arallel shaft gears and as 1L of fll #ower #er stage for #lanetary
gears. In #ractice #recise dimensioning of gearbo5 is of im#ortance. %therwise
maintenance and o#eration will e5#erience many #roblems and the lifetime will be
aff ected.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 35
8/19/2019 Chapter Content Final
36/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
$.4 O9*+-,%(& S*?*&* -&' C(&,+(
$.4.1 O9*+-,%(& S*?*&*
%#eration se&ence of the wind trbine is determined by means of three
thresh" old #oints.
t in velocity ϑI which is the wind s#eed the wind trbine starts to deliver
ot#t #ower. ;or instance, in )>WT s ca#tred #ower for low wind s#eeds is
negative, and the ct in velocity has to be chosen at vales greater than the wind
s#eed at which #ower coefficient becomes #ositive.
The rated wind velocity ϑ is the wind s#eed at which the ca#tred #ower reachesthe generator rated #ower.
The ct ot velocity ϑ% is the highest wind s#eed at which the wind energy system
is able to o#erate mechanically safe. Ty#ically this is less than 2H m?s .
>s a reslt, o#eration se&ence of a wind trbine is divided into, at least, for
regions.
egion1, at which the wind s#eed is less than the ct in s#eed. In this region,
ca#tred #ower does not sfficient to com#ensate the internal consm#tion and
losses. /ence the trbine is #ar$ed and is not rn.
egion 2, at which the wind s#eed is between the ct in s#eed and the rated s#eed.
It is sometimes called sb"rated region and the wind trbine is controlled sing
-a5imm 7ower 7oint Trac$ing'-77T* in order to achieve the o#timm ti# s#eed
ratio. -77T is introdced thoroghly in sbsection 2.4.2 .
egion , at which the wind s#eed is between rated s#eed and ct ot s#eed. In this
region, there are varios control o#tions, namely constant rotor s#eed, constant rotor
tor&e and constant rotor #ower. The +rst two ,comes with the ris$ of tor&e and
crrent overload and they need additional control measres for overload #rotection. In
the latter two, the s#eed does not reach to the rated s#eed, therefore constant rotor
#ower is #ro#osed .
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 36
8/19/2019 Chapter Content Final
37/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
egion 4, at which the wind s#eed e5ceeds the ct ot s#eed and the wind trbine is
sht down.
$.4.$ C(&,+(
The #r#ose of the control is to limiting the tor&e and the #ower e5#erienced
by the drive train in order to increase lifetime. -a5imising the energy yield for
varios conditions.
ngle of attac$ 'blade #itching*
;low velocity 'variable s#eed rotor*
lade si!e 'variable blade length*
lade section aerodynamics
The +rst two methods are im#lemented in most of all modern />WT s and the wor$
#rinci#le behind the control of the #ower coefficient. They are introdced in the
following sbsections.
The wor$ing #rinci#le behind the variable diameter blade is the control of the swe#t
area that is sefl for minimising the load dring high wind s#eeds. ontrol of blade
section aerodynamics is im#lemented by means of active ow control. This state of
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 37
8/19/2019 Chapter Content Final
38/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
the art method is growing ra#idly and has the #otential to be im#lemented on large
scale />WT s.
Generally, control can be im#lemented in either active or #assive way, de#ending on
tili!ation of e5ternal energy. aw mechanism ,blade #itching and variable s#eed
rotors are e5am#les of contem#orary active control methods.
B-'* P%,%&
In a conventional control method of />WTs the #itch angle of the rotor blade is
changed mechanically. lade #itching means that the blades are trned along their
longitdinal a5is with the hel# of an active mechanical device. In this way, the angle
of attac$ and thereby also the absorbed #ower varies. The angle of attac$ can be
changed in two diff erent ways either by decreasing or increasing it. oth cases redce
the ca#tred #ower, #rovided that the angle of attac$ is in a condition where the
#ower coefficient is at the ma5imm. The former re&ires higher blade #itching for
the same diff erence in the #ower coefficient. /ence, the ot#t #ower is controlled
more #recisely.
;i5ed"s#eed"+5ed"blade )>WTs sff er from high demands on the self stall
reglation #ro#erty. 3sally, small scale )>WT s are not e&i##ed with the blade
#itching control for sim#licity reasons. In +5ed blade )>WTs, at which the rotor
s#eed is $e#t constant, the more the wind s#eed increases, the larger the angle of
attac$ becomes. Ths the amont of stall will increase as well. In +5ed s#eed wind
systems, which are connected to the grid directly, the rotor s#eed is constant and
accordingly the self reglatory stall is always #resent.
;rom the wind system com#onentsF #oint of view, there are several demand #ointswhich are listed below
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 38
8/19/2019 Chapter Content Final
39/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
CHAPTER 3
DEVELOPMENT OF PROPOSED DC MICROGRID
F%. 3.1. L-2(, (< ,* DC M%+(+%'.
> schematic of the dc microgrid with the conventions em#loyed for #ower is
given in ;ig..1. The dc bs connects wind energy conversion system 'W(*, 7)
#anels, mltilevel energy storage com#rising battery energy storage system '(*
and s#erca#acitor, () smart charging #oints, () fast charging station, and grid
interface. The W( is connected to the dc bs via an ac:dc converter. 7) #anels are
connected to the dc bs via a dc:dc converter. The ( can be reali!ed throgh flow
battery technology connected to the dc bs via a dc:dc converter. The s#erca#acitor
has mch less energy ca#acity than the (. ather, it is aimed at com#ensating for
fast flctations of #ower and so #rovides cache control as detailed in P1KQ. Than$s to
the mltilevel energy storage, the intermittent and volatile renewable #ower ot#ts
can be managed, and a deterministic controlled #ower to the main grid is obtained by
o#timi!ation. 7roviding ninterr#tible #ower s##ly '37*
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 39
8/19/2019 Chapter Content Final
40/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;ig. .2 %verview of o#timi!ed schedling a##roach.
ervice to loads when needed is a core dty of the rban microgrid. () fast
charging introdces a stochastic load to the microgrid. The mltilevel energy storage
mitigates #otential im#acts on the main grid. In bilding integration, a vertical a5is
wind trbine may be installed on the roofto# as shown in ;ig..2. 7) #anels can be
co"located on the roofto# and the facade of the bilding. ch or similar
configrations benefit from a local availability of abndant wind and solar energy.
The fast charging station is reali!ed for #blic access at the grond level. It is
connected close to the ):-) transformer to redce losses and voltage dro#. ()s
#ar$ed in the bilding are offered smart charging within ser"defined constraints
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 40
8/19/2019 Chapter Content Final
41/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
3.1 OPERATIONAL OPTIMI@ATION OF MICROGRID FOR
RENEWABLE ENERGY INTEGRATION
The algorithm for o#timi!ed schedling of the microgrid is de#icted in ;ig..2.
In the first stage, wind and solar #ower generation are forecast. The ncertainty of the
wind and solar #ower is #resented by a three"state model. >n e5am#le of sch a
forecast is shown in ;ig. tate 1 re#resents a #ower forecast lower than the average
#owerforecast. This state is shown by the #ower forecast of P 1 with the forecast
#robability of pr 1 assigned to it. The average #ower forecast and the #robability of
forecast assigned to it give state 2. tate re#resents a #ower forecast higher than the
average #ower forecast. Then, wind and solar #ower forecasts are aggregated to
#rodce the total renewable #ower forecast model.
This aggregation method is formlated in ection III">. The aggregated #ower
generation data are sed to assign horly #ositive and negative energy reserves to the
( for the microgrid o#eration. The #ositive energy reserve of the ( gives the
energy stored that can be readily in9ected into the dc bs on demand. The negative
energy reserve gives the #art of the ( to remain ncharged to ca#tre e5cess
#ower on demand. (nergy reserve assessment is #erformed according to the
aggregated renewable #ower generation forecast. In order to com#ensate for the
ncertainty of the forecast, a method is devised to assess #ositive and negative energy
reserves in ection III". ;inally, the emission constrained cost o#timi!ation is
formlated to schedle the microgrid resorces for the day"ahead dis#atch. The
o#timi!ed schedling is formlated in ection III".
3.$. AGGREGATED MODEL OF WIND AND SOLAR POWER
FORECAST
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 41
8/19/2019 Chapter Content Final
42/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
where pr > ,m is the forecast #robability of renewable #ower at the aggregated state
m, and prl,m is the forecast #robability of renewable #ower at the combined state l
within the aggregated state m. The average #ower of each aggregated state is
calclated by the average weighting of all #ower ot#ts in the aggregated state m
where P > ,m is the #ower forecast of renewables at the aggregated state m,
and Pl,m is the #ower forecast at the combined state l within the aggregated state m.
In the e5am#le shown in Table II, the combined model is redced to a three"state wind
and solar #ower forecast model. (m#loying '1* and '2*, the calclation is shown for
aggregated state 1 in the following=
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 42
8/19/2019 Chapter Content Final
43/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
In the e5am#le shown in Table II, the combined model is redced to a three"state wind
and solar #ower forecast model. (m#loying '1* and '2*, the calclation is shown for
aggregated state 1 in the following Wind and solar #ower generation forecast
ncertainty data are made available for the rban microgrid. #ecifically, as shown in
;ig. 4, the ot#t #ower state and the #robability assigned to that state are available.
In the three"state model, the nmber of individal states is K U . > sam#le of forecast
data of the wind and solar #ower generation is #rovided for 1 h, as shown in Table I.
;or e5am#le, at a #robability of H0L the wind #ower will be H0 $W in state 2.
The aggregation of ot#t #ower states of the wind and solar #ower is formed as
follows. >s the microgrid has two generation resorces with three individal states, K
U , the nmber of combined states is U K 2, which is e&al to nine in this case. The
combined states in the forecast ncertainty model of wind and solar #ower are shown
in ;ig. H. In each combined state, the #ower of those individal states is smmed #,
and the #robability of a combined state is the #rodct of the #robabilities in individal
states assming that the individal states are not correlated.
;or the wind and 7) #ower forecast shown in Table I, nine combined states are
defined. Those states are #rovided in Table II. The combined states, as shown by the
e5am#le in Table II, shold be redced to fewer re#resentative states. To aggregate the
combined states, ! aggregated states are defined. In this e5am#le ! U . Those statesare shown in Table II and denoted by m. The borders between aggregated state m
states are determined based on the borders between individal states in Table I. The
average renewable #ower of individal states 1 and 2 is J2.H $W and gives the border
between aggregated states 1 and 2. i$ewise, the average renewable #ower of
individal states 2 and gives the border between aggregated states 2 and . If an
aggregated state m covers a nmber of combined states ", the #robability of having
one of those aggregated states is the sm of the #robabilities of those combined states.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 43
8/19/2019 Chapter Content Final
44/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
3.3.ENERGY RESERVE ASSESSMENT FOR OPERATION OF MICROGRID
Ta$ing into accont the aggregated wind and solar #ower forecast model
develo#ed above, an illstrative e5am#le is #rovided to show how the energy reserve
is assessed. In Table I), an aggregated three"state #ower forecast model for three
continos hors is assmed. The aggregated #ower forecast for hor 1 is ta$en from
the e5am#le solved in ection III">. The aggregated #ower forecast of hors 2 and
is calclated by the same method. >s shown in Table I), the #robability of having
real"time #ower ot#t at state 1 in three continos hors is e&al to the #rodct of
the #robabilities in state 1 for those three hors. This #robability is ths e&al to
0#18MH U 0#00JHK. This is also the same #robability for having state in three
continos hors. The #robability is very small. Therefore, the ( has enogh
negative energy reserve to cover for ncertainty for three sccessive hors if the
following condition is met=
7ower at aggregated state re#resents the #ower forecast higher than average, state 2.
Therefore, the negative reserve that is sed to ca#tre e5cess energy is calclated by
smmation of the energy #ertaining to state mins the energy #ertaining to state 2 in
a "h window.
This means that the microgrid has, at the high #robability of 1A0#18MH, the
free ca#acity in the ( to ca#tre the e5cess of renewable energy for a "h window.
imilar to the negative energy reserve assessment, the #ositive energy reserve is
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 44
8/19/2019 Chapter Content Final
45/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
assessed. In order to calclate the #ositive energy reserve for the e5am#le shown in
Table I), energy of state 2 is sbtracted from energy of state 1 for all three hors, and
the reslts are smmed #. 7ositive energy reserve is the stored energy in the (
ready to be in9ected into the dc bs to mitigate less renewable #ower generation thane5#ected
imilar to the e5am#le solved for 1 h in Table III, the aggregated model shold
be develo#ed for the whole dis#atch #eriod. ;or instance, if the schedling hori!on is
24 h, a window swee#s the hori!on in 24? bloc$s. Ths, eight bloc$s of reserve will
be determined. oth #ositive and negative energy reserves are considered in the (
energy constraint. ased on the o#eration strategy, ( storage ca#acity allocation
is shown in ;ig. J. The de#th of discharge '
8/19/2019 Chapter Content Final
46/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
microgrid. In this ob9ective fnction, P G and P () are to be determined by
o#timi!ation. The first term in the ob9ective fnction above e5#resses the energy cost,
the second term defines the cost of () smart charging, and the third term describes
the emission cost.
>s shown in ;ig. 1, for #ositive vales of P G, the microgrid draws #ower
from the main grid, and for negative vales of P G the microgrid in9ects #ower into the
main grid. The emission term #enali!es #ower flow from the main grid to the
microgrid. If the microgrid draws #ower from the main grid, the microgrid wold
contribte to emissions of the #ower system. %n the other hand, as the microgrid has
no nit that #rodces emission, when the microgrid retrns #ower to the main grid, it
contribtes to emission redction. The o#timi!ation #rogram determines a soltion
that minimi!es theo#eration cost of the dc microgrid. Ths, a monetary vale
isassigned to emission redction by this a##roach. This ob9ective fnction is sb9ect
to the constraints as follows.
1* 7ower limitation of the grid interface introdces a bondary constraint to the
o#timi!ation
where P GA is the lower bondary of the grid #ower, and P GB is the ##er bondary
of the grid #ower.
2* The ( #ower has to be within the limits
where P (A is the lower bondary of the otgoing #ower from the ( to the dc
bs, P ( is the ( #ower to the dc bs, and P (B is the ##er bondary of
the ( #ower
* The availability of () and charging #ower limits shold be met
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 46
8/19/2019 Chapter Content Final
47/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
where P () is the () charging #ower, P ()B is the ##er bondary of the ()
charging #ower, and T () gives the hors in which ()s are available for smart
charging.
4* The #ower balance e&ation has to be valid at all simlation time ste#s
where P > ,2 is the average #ower forecast of renewable energy sorces wind and
solar at aggregated state 2, and P (); is the () fast charging #ower forecast.
H* The ob9ective fnction is also sb9ect to a constraint of the % of the (. In
order to inclde 37 service, the formlation of the o#timi!ation is modified.
>##lication is to s##lying loads by the microgrid for a de+ned time s#an in
the case of a contingency. It is devised so that the microgrid #rovides bac$# #ower
for a commercial load sch as a ban$ branch or an of+ce dring wor$ing hors.
where & (A is the lower bondary of energy ca#acity of the (,
& ("0 is the % of the ( at the beginning of the o#timi!ation, )& ( is the
discharged energy from the ( to the dc bs at every minte, and & (B is the
##er bondary of energy ca#acity of the (. The % of the battery at all time
ste#s shold be in the o#eration !one of the (. Therefore, in this e&ation, the% of the battery is calclated and chec$ed to be within the ##er and lower %
limits. antities & (A, & (B, and )& ( are calclated
as follows=
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 47
8/19/2019 Chapter Content Final
48/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
where & (B is the ##er bondary of ( %, &C ( is the energy
ca#acity of the (, and &C "h is the negative energy reserve of the (. The
discharged energy from the ( to the dc bs is calclated by where )& ( is the
discharged energy from the (
to the dc bs in every minte, *dis is the discharging efficiency of the (, *ch is
the charging efficiency of the (, and % min is the time ste# si!e e&al to 1 min.
J* The total re&ired () smart charging energy for the day"ahead schedling is to be
met. This is defined by
;ig..
.
8/19/2019 Chapter Content Final
49/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
where T () is the time that ()s are available for smart charging by the microgrid,
P () is the smart charging #ower of ()s, and &C ()"ch is the total () smart
charging energy forecast for the day"ahead schedling
3.5. ADAPTIVE DROOP CONTROL OF BESS
In this section, the real"time o#eration of the microgrid in the interconnected
and atonomos modes is stdied. In the interconnected mode of o#eration, an
ada#tive droo# control is devised for the (. The ada#tive droo# characteristic of
the ( #ower electronic converter is selected on the basis of the deviation between
the o#timi!ed and real"time % of the (, as calclated in ection III.
8/19/2019 Chapter Content Final
50/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
The first droo# crve, as shown in ;ig, is devised for a case where the real"
time % of the ( is within close range of the o#timi!ed % of the ( from
the schedling calclated in ection III". The acce#table realtime % is determined
throgh definition of ##er and lower bondaries arond the o#timi!ed %. If the
real"time % is within these bondaries, the droo# control of the ( #ower
electronic converter is selected as shown in ;ig.To s##ort the dc voltage. In this case,
the ##er bondary and the lower bondary lead to a symmetrical droo# res#onse. In
the voltage range between V m1A and V m1B, battery storage does not react to the
voltage deviations of the dc bs.
In the voltage range from V m1A to V m2A and also from V m1B to
V m2B, the droo# control of the ( reacts. Therefore, )P ( modifies the
#ower ot#t P ( to mitigate the voltage deviation of the dc bs. ;inally, in the
voltage range from V m2A to V A and also from V m2B to V B, the droo# crve
is in a satration area, and ths the ( contribtion is at its ma5imm and
constant.The second droo# crve as shown in ;ig. 8 is devised for a sitation where
the real"time % of the ( is lower than the o#timi!ed and schedled % of the
(. Therefore, the ( contribtes to stabili!ing the dc bs voltage by charging
at the same #ower as shown in ;ig.
/owever, the ##er bondary of the ( droo# res#onse is redced by the
factor +, and it is e&al to + ・ )P ("
8/19/2019 Chapter Content Final
51/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
bs voltage by discharging at the same #ower as shown in ;ig. M. /owever, the lower
bondary of the ( droo# res#onse is modified by the factor +, and it is e&al to A+
)P ("
8/19/2019 Chapter Content Final
52/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
CHAPTER 4
SIMULATION THEORY
4.1 GENERAL
->T> 'matri5 laboratory* is a nmerical com#ting environment and forth"
generation #rogramming langage. T> allows
matri5 mani#lations, #lotting of fnctions and data, im#lementation of algorithms,
creation of ser interfaces, and interfacing with #rograms written in other langages,
inclding , BB, Cava, and ;ortran. >lthogh ->T> is intended #rimarily for
nmerical com#ting, an o#tional toolbo5 ses the -7>< symbolic engine,
allowing access to symbolic com#ting ca#abilities. >n additional #ac$age, imlin$,
adds gra#hical mlti"domain simlation and -odel"ased T> had arond one million sers across indstry and academia.
->T> sers come from varios bac$gronds of engineering, science, and
economics. ->T> is widely sed in academic and research instittions as well as
indstrial enter#rises.
4.$ MATLAB HISTORY
leve -oler , the chairman of the com#ter"science de#artment at the
3niversity of ew -e5ico, started develo#ing ->T> in the late 1KM0s. /e
designed it to give his stdents access to I7>@ and (I7>@ withot them
having to learn ;ortran. It soon s#read to other niversities and fond a strong
adience within the a##lied mathematics commnity. Cac$ ittle, an engineer, was
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 52
http://en.wikipedia.org/wiki/Numerical_analysishttp://en.wikipedia.org/wiki/Fourth-generation_programming_languagehttp://en.wikipedia.org/wiki/Fourth-generation_programming_languagehttp://en.wikipedia.org/wiki/MathWorkshttp://en.wikipedia.org/wiki/Matrix_(mathematics)http://en.wikipedia.org/wiki/Function_(mathematics)http://en.wikipedia.org/wiki/Algorithmhttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/C_(programming_language)http://en.wikipedia.org/wiki/C%2B%2Bhttp://en.wikipedia.org/wiki/Java_(programming_language)http://en.wikipedia.org/wiki/Fortranhttp://en.wikipedia.org/wiki/MuPADhttp://en.wikipedia.org/wiki/Computer_algebra_systemhttp://en.wikipedia.org/wiki/Computer_algebra_systemhttp://en.wikipedia.org/wiki/Symbolic_computinghttp://en.wikipedia.org/wiki/Simulinkhttp://en.wikipedia.org/wiki/Model_based_designhttp://en.wikipedia.org/wiki/Dynamical_systemhttp://en.wikipedia.org/wiki/Embedded_systemshttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Economicshttp://en.wikipedia.org/wiki/Cleve_Molerhttp://en.wikipedia.org/wiki/Computer_sciencehttp://en.wikipedia.org/wiki/University_of_New_Mexicohttp://en.wikipedia.org/wiki/LINPACKhttp://en.wikipedia.org/wiki/EISPACKhttp://en.wikipedia.org/wiki/Fortranhttp://en.wikipedia.org/wiki/Applied_mathematicshttp://en.wikipedia.org/wiki/John_N._Littlehttp://en.wikipedia.org/wiki/Fourth-generation_programming_languagehttp://en.wikipedia.org/wiki/Fourth-generation_programming_languagehttp://en.wikipedia.org/wiki/MathWorkshttp://en.wikipedia.org/wiki/Matrix_(mathematics)http://en.wikipedia.org/wiki/Function_(mathematics)http://en.wikipedia.org/wiki/Algorithmhttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/C_(programming_language)http://en.wikipedia.org/wiki/C%2B%2Bhttp://en.wikipedia.org/wiki/Java_(programming_language)http://en.wikipedia.org/wiki/Fortranhttp://en.wikipedia.org/wiki/MuPADhttp://en.wikipedia.org/wiki/Computer_algebra_systemhttp://en.wikipedia.org/wiki/Symbolic_computinghttp://en.wikipedia.org/wiki/Simulinkhttp://en.wikipedia.org/wiki/Model_based_designhttp://en.wikipedia.org/wiki/Dynamical_systemhttp://en.wikipedia.org/wiki/Embedded_systemshttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Economicshttp://en.wikipedia.org/wiki/Cleve_Molerhttp://en.wikipedia.org/wiki/Computer_sciencehttp://en.wikipedia.org/wiki/University_of_New_Mexicohttp://en.wikipedia.org/wiki/LINPACKhttp://en.wikipedia.org/wiki/EISPACKhttp://en.wikipedia.org/wiki/Fortranhttp://en.wikipedia.org/wiki/Applied_mathematicshttp://en.wikipedia.org/wiki/John_N._Littlehttp://en.wikipedia.org/wiki/Numerical_analysis
8/19/2019 Chapter Content Final
53/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
e5#osed to it dring a visit -oler made to tanford 3niversity in 1K8. ecogni!ing
its commercial #otential, he 9oined with -oler and teve angert. They rewrote
->T> in and fonded -athWor$s in 1K84 to contine its develo#ment. These
rewritten libraries were $nown as C>@7>. In 2000, ->T> was rewritten to sea newer set of libraries for matri5 mani#lation, >7>@ .
->T> was first ado#ted by researchers and #ractitioners in control engineering,
ittle6s s#ecialty, bt &ic$ly s#read to many other domains. It is now also sed in
edcation, in #articlar the teaching of linear algebra and nmerical analysis, and is
#o#lar amongst scientists involved in image #rocessing.
4.3 SIMULIN
imlin$, develo#ed by -athWor$s, is a commercial tool for modeling,
simlating and analy!ing mlti"domain dynamic systems. Its #rimary interface is a
gra#hical bloc$ diagramming tool and a cstomi!able set of bloc$ libraries. It offers
tight integration with the rest of the ->T> environment and can either drive
->T> or be scri#ted from it. imlin$ is widely sed in control theory and digital
signal #rocessing for mlti"domain simlation and -odel"ased
8/19/2019 Chapter Content Final
54/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
The imlin$ ibrary rowser contains a library of bloc$s commonly sed to
model a system. >s shown in ;ig.4.2, these inclde=
;ig.4.1. ilding a new model
ontinos and discrete dynamics bloc$s, sch as Integration and 3nit lgorithmic bloc$s, sch as m, 7rodct, and oo$# Table trctral bloc$s, sch
as -5, witch, and s elector.
We can bild cstomi!ed fnctions by sing these bloc$s or by incor#orating
hand"written ->T>, , ;ortran, or >da code into the model.The cstom bloc$s
can be stored in their own libraries within the imlin$ ibrary rowser.
_______________________________________________________________________________
/(%3 (GI((IG %(G( Page | 54
8/19/2019 Chapter Content Final
55/80
INTEGRATION OF RENEWABLE ENERGY SOURCES FOR DC MICROGRID APPLICATIONS _______________________________________________________________________________________
;ig.4.2. ommonly sed bloc$s
imlin$ add"on #rodcts let yo incor#orate s#eciali!ed com#onents for aeros#ace,
commnications, 7I< control, control logic, signal #rocessing, video and image
#rocessing, and other a##lications. >dd"on #rodcts are also available for modeling
#hysical systems with mechanical, electrical, and hydralic com#onents.
To bild a model as shown in ;ig.4.1 by dragging bloc$s from the imlin$ ibrary
rowser into the imlin$ (ditor, we then connect these bloc$s with signal lines to
establish mathematical relationshi#s between system com#onents. Gra#hical
formatting tools, sch as smart gides and smart signal roting, hel# we control the
a##earance of the model as webild it. We can add hierarchy by enca#slating a
gro# of bloc$s and signals as a sbsystem in a single bloc$.
The imlin$ (ditor gives a com#lete control over what we see and se within the
model. ;or e5am#le, we can add commands and sbmens to the editor and conte5t
mens. We can also add a cstom interface to a sbsystem or model by sing a mas$
that hides the sbsystem6s contents and #rovides the sbsystem with its own icon and
#arameter dialog bo5.
4.4.$ N-8%-,%& T+( ,* M('* H%*+-+2
The (5#lorer bar and -odel ro