design and implementation of thyristor switched shunt capacitors a ...

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i + V + T1 T2 - VT Ctsc (V(0) = V co ) (a) Circuit for analysis of TSC in ideal circumstances. 1.2 kV Source Voltage Line Current 1200 A 0.8 kV 800 A 0.4 kV 400 A Source Voltage 0 V -0.4 kV 0 A -400 A Line Current -0.8 kV -1.2 kV 180 ms Thyristor Switch turn-on instant 200 ms 220 ms 240 ms 260 ms 280 ms Time -800 A -1200 A (b) Supply voltage and phase current waveforms after the switching occurs. Voltage 2.0 kV 1.6 kV 1.2 kV 0.8 kV 0.4 kV 0 V -0.4 kV -0.8 kV -1.2 kV Capacitor Voltage Thyristor Voltage -1.6 kV -2.0 kV -2.4 kV -2.8 kV 180 ms Thyristor Switch turn-on instant 200 ms 220 ms 240 ms 260 ms 280 ms Time (c) Capacitor voltage and thyristor voltage waveforms after the switching occurs. Figure 2.13: The behavior of an ideal TSC. Capacitors are initially charged. 32
is known as copper loss of the transformer and for a typical transformer, it is approximately 1% of its power rating. The formula below explain how to obtain the leakage inductance: L tr = V 2 U k 2πfS . (2.20) where U k is the transformer’s short circuit impedance rating (If the transformer’s secondary terminal is short circuited line to line, primary terminal voltage increases from zero volts to a level at which U k V secondary appears at the secondary terminal). The inrush limiting reactor or a filter reactor is determined depending on the tuning frequency and can be calculated by 2.2. In this equation, there are three unknowns. The capacitance is derived from the required reactive power of the system as mentioned in Section 2.2.1. The tuning frequency is chosen according to the system overall frequency characteristics and also explained in Section 2.2.2. From these values, the inductance can be obtained. Its internal resistance can be obtained by 2.21 where Q is called the Quality Factor of the inductor. It can be easily seen that Q represents the ratio of inductive reactance at tuned frequency to its internal resistance. The quality factor of an ordinary inductor can be found in its datasheet. R = wL Q . (2.21) In Figure 2.14(b), the initial condition of capacitor is zero volts. Therefore, thyristor carries only the supply voltage. After switching on, the voltage across the thyristor drops to zero (or almost zero as it has a small internal resistance that creates negligible voltage drop) and, the capacitor and inductor in series start to be charged. However, there is a current flowing back and forth between these two storage devices at the tuning frequency until the stable point is found and current flow becomes smooth (Figure 2.14(c)). The series resistance R L helps this oscillation to damp out and to reach a stable point. If the circuit did not include any resistance, then the oscillations would continue forever. If the nonlinear behavior of thyristor is also taken into account, then some other 33
Page 1 and 2: DESIGN AND IMPLEMENTATION OF THYRIS
Page 3 and 4: I hereby declare that all informati
Page 5 and 6: ÖZ TRİSTÖR ANAHTARLAMALI ŞÖNT
Page 7 and 8: ACKNOWLEDGMENTS I would like to exp
Page 9 and 10: 2.3 Switching Performance of TSC .
Page 11 and 12: LIST OF TABLES TABLES Table 1.1 Cur
Page 13 and 14: Figure 2.9 (a) Equivalent circuit r
Page 15 and 16: Figure 4.8 Resultant line-to-line v
Page 17 and 18: Figure 4.38 3 Phase current wavefor
Page 19 and 20: CHAPTER 1 INTRODUCTION 1.1 Power Qu
Page 21 and 22: this disturbance since they do not
Page 23 and 24: driving algorithm and it has to wit
Page 25 and 26: how to improve the transient respon
Page 27 and 28: From the practical view, the less t
Page 29 and 30: CHAPTER 2 PROBLEM DEFINITION AND PR
Page 31 and 32: as switching devices instead of ant
Page 33 and 34: Directly Connected Clients 35 33 30
Page 35 and 36: 2.2.2 Harmonic Filtration A pure si
Page 37 and 38: components dramatically. The follow
Page 39 and 40: 20A 20A 15A 15A Line Current 10A Li
Page 41 and 42: VS RS XS VL Source Load IL Ic Compe
Page 43 and 44: a couple of cycles. However, at lea
Page 45 and 46: i + + VT - T1 T2 V + VC - L C Figur
Page 47 and 48: 2.15 shows that there are some comp
Page 49: waveform directly follows the sourc
Page 53 and 54: components parallel to the thyristo
Page 55 and 56: Ls Coupling Transformer V TCR TSC L
Page 57 and 58: +1.0 Reactive Power, Q (pu) Inducti
Page 59 and 60: V V max V max = voltage limit I Cma
Page 61 and 62: power system. Voltage source conver
Page 63 and 64: timing of switching must be when th
Page 65 and 66: Table 3.1: Type of the excavators a
Page 67 and 68: 3.3 Selection Criterion of Capacito
Page 69 and 70: minutes should be given to self-dis
Page 71 and 72: possible in order to achieve a tran
Page 73 and 74: advantage. It is not affected by th
Page 75 and 76: (a) (b) Figure 3.7: PSCAD model of
Page 77 and 78: this value is at least twice of the
Page 79 and 80: of the reverse recovery current and
Page 81 and 82: curve in its datasheet should be ta
Page 83 and 84: Figure 3.13: The current distributi
Page 85 and 86: stays in inductive or capacitive re
Page 87 and 88: ”ENB A, ENB B and ENB C” are co
Page 89 and 90: 3.7 Key Points in Design of TSC Cab
Page 91 and 92: chapter, some basic calculations to
Page 93 and 94: CHAPTER 4 EXPERIMENTAL RESULTS 4.1
Page 95 and 96: (a) Contactor Switched Plain Capaci
Page 97 and 98: ated capacitor current. This inrush
Page 99 and 100: current. Line-to-line voltage is al
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(a) Three phase current waveform at
Page 103 and 104:
4.2.2 Contactor Switched Shunt Filt
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to high inrush current causes a con
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(a) Voltage Waveform across the cap
Page 109 and 110:
Page 111 and 112:
This transient has also negligible
Page 113 and 114:
(a) Three phase current waveform at
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Figure 4.17: Resultant 3φ Capacito
Page 117 and 118:
Page 119 and 120:
Figure 4.21: Resultant line-to-line
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Figure 4.24: Firing pulses, voltage
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566 uF 2x6.0 MVA TM 34.5 kV 500 / 5
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Experimental results will be presen
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+1.6 +0.66 Thyristor Voltage (kV) -
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+1.5 +1.0 Capacitor Voltage (kV) +0
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+1.5 +1.0 Capacitor Voltage (kV) +0
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increase in current can be approxim
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would be given to the supply voltag
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250 1 cycle transient fft 200 I Pha
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4.4 TSC Cabinet Interior Equipment
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4.5 Discussion In contactor or thyr
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• Delta-connected TSC topology is
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[13] Tabandeh, M., Alavi, M.H., Mar
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[38] Bilgin, H.F., “Design and Im
Page 149 and 150:
Since the roots of this equation ar
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APPENDIX B DISTINCTIVE CURVES OF TH
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135 Figure B.2: Stored charge and r
Page 155 and 156:
APPENDIX C DETAILS OF THE CONTROL C
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139 Figure C.2: P-CAD 2002 Schemati
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Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
147 Figure C.10: P-CAD 2002 Schemat
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149 Figure D.1: General view of the
Page 169 and 170:
APPENDIX E APPLICATION MODEL OF THE
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153 Figure E.2: 3 dimensional plot
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155 Figure F.1: Installed SVC syste
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157 Figure F.3: Installed SVC syste
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