BG Fernandes Department of Electrical Engineering II T - Power ...

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• Start the cycle again after T s when integrator resets • K. M. Smedley & C. Qiao, “Unified constantfrequency integration control of active power filters –steady –state and dynamics” IEEE Transaction on power electronics, vol. 16, No. 3, May 2001 Application of Power Electronics in Power Systems B. G. Fernandes 156/454
1φ AC-DC Control technique (1 − 2D ) V = i m s V R c V m = → Emulated resistance e Application of Power Electronics in Power Systems B. G. Fernandes 157/454
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EE 660 Application of Power Electro
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Books for Reference • T. J. E. Mi
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• Consumption of Electricity are
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• Thermal limit (depends on ambie
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• Voltage profile along the line
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• To control V R & ↑ power tran
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• High ‘V’ & high KVar source
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• What sort of PWM technique to u
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V = V = V = m S R V It can be shown
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Provide • Series capacitive compe
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• Is it possible to change the ph
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• Injecting V in series with line
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• Definite amount of power that s
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• To control the power flow & to
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• Most of the loads are Non-linea
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Current drawn by the load fed from
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Effect of harmonics: A. In the Rota
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Conclusions • Load compensator +
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Notation of quality of supply • H
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Ideal compensator • Correct the p
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Voltage regulation • Which is the
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I L = P L − V jQ L ΔV = ( R + jX
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Vary Q S => ΔV rotates till E = V
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• Approximate relationship for vo
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• If short circuit resistance of
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I a = V R ab Vca − jX VL∠0 V∠
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I b = I c ∠120 ⎛ ⎜ ⎝ 3 2X
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Contd.. • Using passive reactive
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Comments • Branch currents of Δ
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Application of Power Electronics in
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• May not be possible • Most of
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• Can be shown that if V < C1 V S
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• M => Magnitude of sine wave (no
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Review • Linear lagging load can
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Contd.. • If space vector PWM is
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⇒ (n-1) harmonics are eliminated
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• Assume that there are 5 switchi
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• Non-linear transcendental equat
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How to calculate Ref. Var ? i = I m
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Controlled current SLCVC • Compen
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Control strategy -I Application of
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Review • In harmonic elimination
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Contd.. Controlled current SLCVC
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• i S * is in phase with v S •
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• If Inverter i S * is changed in
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• Use two compensators & connect
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• Main compensator ⇒ Voltage co
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i Cm1 = V S −VCm 1∠ −δ Z∠
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• Var calculator determines V * d
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Contd.. • For high power applicat
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[A] [v'] = [z] [A] [i'] [v'] = [A]
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Vector representation of instantane
Page 105 and 106: [ C] t = ⎡ ⎢ ⎢− ⎢ ⎣−
Page 107 and 108: ⎡v ⎢ ⎢ v ⎢⎣ v a b c ⎤
Page 109 and 110: e e i i α β α β = = V V S S cos
Page 111 and 112: Application of Power Electronics in
Page 113 and 114: e . q i * = β α C 3 2 + ( 2 2 ) e
Page 115 and 116: • Frequency of e α , i α , e β
Page 117 and 118: Review Instantaneous real power P =
Page 119 and 120: Contd.. Application of Power Electr
Page 121 and 122: Change of reference frame q S d S d
Page 123 and 124: • Let us assume that v S is along
Page 125 and 126: • AC filtering ⇒ phase shift
Page 127 and 128: • Information about system freque
Page 129 and 130: * x ∫ ω xt () x y n + 1 − Δ t
Page 131 and 132: e α = e a − 1 2 e b − 1 2 e c
Page 133 and 134: e d e d = = = e e s e s α cos( θ
Page 135 and 136: Review • In synchronous rotating
Page 137 and 138: To change MI using harmonic elimina
Page 141 and 142: • 3φ sinusoids which are in phas
Page 143 and 144: • This voltage waveform can be us
Page 145 and 146: 1 1 • = = Switching frequency T T
Page 147 and 148: • Assume that over one cycle V re
Page 149 and 150: Rule to be followed • A term in t
Page 151 and 152: S 4 , S 3 ON for DT S : di L = V s
Page 153 and 154: Aim • i s and V s should be in ph
Page 155: Contd.. • Generate reset pulse at
Page 159 and 160: Alternate Approach DC-DC Converter
Page 161 and 162: • Information regarding V s shoul
Page 165 and 166: Inverter topology for high power ap
Page 167 and 168: • Number of pulse should be high
Page 169 and 170: Switches ON V AX S1, S2 V dc S2, S3
Page 173 and 174: Review • In one cycle control ‘
Page 175 and 176: Contd.. • At any time 2-devices (
Page 177 and 178: 4-level inverter • Number of swit
Page 179 and 180: S2, S3, S4 ON : ⇒ V AX = 2V dc /3
Page 181 and 182: • ‘V’ rating of D B = 2V dc /
Page 183 and 184: Voltage space vectors for 3 level i
Page 185 and 186: ( NNP ) ⇒ ( 001 ) ⇒ ( PPN ) ⇒
Page 187 and 188: C B A O O N O N O N O O C B A O N N
Page 189 and 190: V q ∴V S = = 3 2 V 2 dC ⎡V ⎢
Page 191 and 192: OOP : V AO = V dC /2, V BO = V CO =
Page 193 and 194: OPO : V AO = V CO = 0, V BO = V dC
Page 195 and 196: Medium voltage vectors ONP : V AO =
Page 197 and 198: NPO : V AO = 0, V BO = V dC /2 , V
Page 201 and 202: Contd.. • No. of medium voltage v
Page 203 and 204: Voltage control • Space vector PW
Page 205 and 206: • Unbalances has no effect on loa
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• Passive elements Load compensat
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Shunt Compensation : • Inject cur
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Mid point voltage regulator • Two
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• Reactive power supplied by the
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• Shunt compensator can increase
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Review Mid-point shunt compensation
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Summary • Compensator must remain
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Variable impedance type S.V.C 1. Th
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• ‘i’ is continuous when α =
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2. Thyristor switched capacitor (TS
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3. Fixed Capacitor, Thyristor contr
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• At α = π/2, Q L = Q L(max)
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Control • ‘Q’ is controlled b
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Operating V-I region Application of
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Contd.. T.S.C • Thyristors are tr
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Advantages • Since voltage profil
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Series compensation • Injects vol
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X eff = ( X − X ) L C = ( 1− K
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Q Q se sh = tan ⎛ ⎜ ⎝ 2 δ ma
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Approaches to controllable series c
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• Amplitude of the fundamental V
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(b). Impedance compensation mode: V
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Review GTO controlled series capaci
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Contd.. • Control ‘i’ in ‘L
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Voltage compensating mode : • Rea
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• In FCTCR continuously varying c
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V 2 1 I1 ⎜ Sin X ⎝ π π ⎛
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• If X L (α) < X C , There are t
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• ‘V C ’ gets distorted • I
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• If X TCR = 1.5X C ⇒ Capacitiv
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Modes of operation By pass mode :
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Static Synchronous Series Compensat
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• Voltage across ‘L’ ⇒ V (
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Contd.. • For both region X L < X
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Control range: • Voltage compensa
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• Compensation for both reactive
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• If V S = V R =V Per phase power
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⇒ Reactive VA associated with the
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Voltage & phase angle regulators Vo
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Power flow control : • Optimal lo
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• Basic idea is to keep the trans
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UPFC : • Able to control simultan
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• Independently control the react
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Case1 : Control capabilities ρ = 0
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U.P.F.C : Review • Two VSI connec
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Using UPFC • Active power flow an
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⇒ A common DC-link voltage is reg
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= Ve ⎧V ⎨ ⎩ ( Cosδ 2 − jSi
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• ‘ρ’ can vary from 0 to 2π
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⇒ Shunt current is controlled ind
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FACTS installments in India • TSC
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HVDC • Long distance transmission
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Back to Back : • Chandrapur - Ram
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• ‘P’ through link can not be
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• If alternator-2 generates 1000
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• One conductor (generally -ve)
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• Each terminal has two converter
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Components of HVDC transmission Bi-
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Smoothing Reactor : Large value of
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Reactive power support : • Both c
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• If α 1 is trigger angle for br
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⇒T 1 is turned off at ωt= 30+ (3
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At ωt = 210 o V a = Sin210 = −1
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At ωt = 330 o V a −1 2, V = 1 =
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At ωt = 300 o V − 3 2, V = 0 V =
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Vdc = 2.34V ph. Cosα =1.35V LL .Co
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Contd.. • As α 1 ↑ (AC-DC conv
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Phase relationship between phase V
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As α↑: • V dc ↓ • Displace
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Boundary conditions : At ωt = α,
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∴V 0 = V pn −V mn V = − 2 cn
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Representation of inverter mode of
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Converter α ⇒ delay angle μ ⇒
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V dco = [cos + cos γ ] − − −
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12-pulse converter • Series conne
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V d ⎛ 3 = VdoCosα − Id . B.
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• 24/36 harmonic filter ⇒ 2*80
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Direct current : • Nominal I ⇒
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Basic control : • DC voltage or I
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Basis for selection of control : Fo
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• Denominator is very small • A
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• P.F should be as high as possib
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• γ ⇒ necessary to maintain a
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I d = V dcor Cosα −V R + R + cr
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• Maintains adequate commutation
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• As taps are changed, CEA regula
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Basic control : • DC voltage or I
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Basis for selection of control : Fo
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• Rectifier control ⇒ To preven
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Control of HVDC system Application
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• Quantities forming the co-ordin
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• Rectifier characteristics can b
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• Constant current characteristic
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• After some time, tap changer ch
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• Therefore rectifier characteris
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• At normal voltage , characteris
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• In order to avoid the problem,
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• When inverter is on current con
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When does change over take place ?
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Review Rectifier characteristics Co
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• ‘e’ is -ve, ‘K’ is +ve
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• Due to line fault or during low
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Inverter side : • I d can be ↑
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Mode stabilization : • Intersecti
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• ‘V’ profile is flat • Con
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• V dcoi Cosβ remains constant
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Current limit Maximum current limit
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Voltage depend current-order limit
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• VDCOL characteristics could be
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Contd.. But I ref(R) > I ref(I) I r
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Contd.. Mode stabilization : • In
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Voltage depend current-order limit
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• VDCOL characteristics could be
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Significant aspects of basic contro
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• If there is a ↓ in AC voltage
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⇒ Achieved using by pass valve an
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• For energization of blocked bri
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• Instead use VSI • ‘I’ cou
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• ‘V’ can not reverse, but
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BG Fernandes Department of Electrical Engineering II T - Power ...

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