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voltage and current waveforms are obtained. Figure 2.1: Various configuration of Thyristor Switched Capacitor Circuit (a) Delta Connection, (b) Wye Connection. Figure 2.2: Representation of an ideal TSC branch. Each phase may include more than one thyristor/capacitor combination to increase the reactive power variation. The number of branches depends on the reactive power required. There is one more topology worth to mention since it has some advantages over classical configurations in several application areas. As can be seen from Figure 2.3, capacitor banks are connected in delta. To increase the benefits of this connection type, thyristor/diode or thyristor/GTO pairs are introduced 12
as switching devices instead of antiparallel connected thyristor pairs [26], [27]. However, careful design of its control mechanism is strictly required since there becomes a considerable stress on the capacitors and the semiconductor switches during turn on/off process which also shorten the lifetime of the materials. Otherwise, the whole system might be exposed to an overcurrent in milliseconds which can damage the insulation of the materials. Moreover, in some variations of this configuration, forced commutated semiconductor switch is necessary to achieve a transient free switching which will be described in Section 2.3. This makes the whole control system even more complicated. R S T Figure 2.3: Alternative Arrangement of TSC: Delta Connected Capacitor Banks. In the remaining sections of this chapter, the application areas, especially TSC used for harmonic filtration, will be explained in details. The transient free switching concept and its necessity will be expressed both theoretically and practically. Lastly, the combinations of TSC with other systems which can be frequently seen in industrial applications are mentioned briefly. 2.2 Application Areas When capacitor switching is considered, reactive power control comes to mind at first. Since the use of medium or large size motors and transformers creating lagging reactive power is increased dramatically in industrial areas over years, the need for capacitive reactive power is inevitable. Also the appreciably quick 13
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: CHAPTER 2 PROBLEM DEFINITION AND PR
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 and 50: waveform directly follows the sourc
Page 51 and 52: is known as copper loss of the tran
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
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Figure 3.13: The current distributi
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stays in inductive or capacitive re
Page 87 and 88:
”ENB A, ENB B and ENB C” are co
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3.7 Key Points in Design of TSC Cab
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chapter, some basic calculations to
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CHAPTER 4 EXPERIMENTAL RESULTS 4.1
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(a) Contactor Switched Plain Capaci
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ated capacitor current. This inrush
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current. Line-to-line voltage is al
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(a) Three phase current waveform at
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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
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Page 111 and 112:
This transient has also negligible
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(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
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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
Page 175 and 176:
157 Figure F.3: Installed SVC syste
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