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link [6]. This helps to balance both active and reactive power in the line. 1.3 Thyristor Switched Capacitor Thyristor Switched Capacitor (TSC) System is a type of SVC shunt to the line. Single phase consists of a number of back-to-back connected thyristor pair in series to a capacitor and a reactor as can be seen from Figure 1.1. The number of branches in one phase depends on the required precision of the reactive power. Due to its countless benefits including simple design and installation, TSC is preferred in many application areas. Some of them can be listed as supply voltage support, reactive power compensation, harmonics filtration, etc. Among these application areas of TSC, the most common one is the reactive power compensation. TSC simply provides capacitive reactive power to the main electricity so that it reduces or cancels the reactive power demand of the large industrial loads. LINE TSC Figure 1.1: General structure of TSC. TSC has been used since early 70s [9], [10], [11]. It was the only tool to improve the transient stability and to compensate the inductive reactive power efficiently. After investigating the benefits of TSC, many researches have been done about 6
how to improve the transient response of capacitor switching. Since the capacitor draws too much current from the main supply at the instant of turn-on, many methods were improved to obtain a transient-free switching. Some of the researchers tried to obtain this concept without any reactor in series to the capacitor, instead they preferred GTO-Thyristor pairs as in [12]. However, GTO brought more complicated control mechanism and increased the cost. As a result of these researches, the thyristor pair started to be switched on at the instant where the line voltage is equal to the voltage across the thyristor. For the same reason, some other control techniques that support to charge the capacitors before switching on for a better transient response were improved [13], [14] and new zero-crossing detectors were utilized with the improvement of technology [15]. TSC can be configured in many different topology such as delta connected capacitors, star connected TSC, thyristor-diode pairs, etc. The delta connected capacitor banks with different power semiconductor switches are investigated in [26] and [27]. However, there is no practical benefits of using this topology. In [42], these topologies were compared according to the voltage and current ratings of the components. TSC has been used for many applications in different purposes over the time. With chronological order, it was used for voltage regulation in [16], arc suppression in [17] and reactive power compensation in [18]. Some commercial TSC systems have been built for different purposes in medium and high voltage levels by ABB and Siemens which are the leading companies in application of these system. In these systems, connection to the busbar is generally made through a step down power transformer. The examples of such systems built by ABB and their purpose of installation are listed below. The industry references of Siemens and companies that design commercial TSC systems in low voltage can also be found in Appendix F. • 150 MVAr TSC for system stability improvement in Zimbabwe [19]. • 94 MVAr TSC for voltage and power quality control in wind power appli- 7
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: driving algorithm and it has to wit
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 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
Page 93 and 94:
CHAPTER 4 EXPERIMENTAL RESULTS 4.1
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(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
Page 101 and 102:
(a) Three phase current waveform at
Page 103 and 104:
4.2.2 Contactor Switched Shunt Filt
Page 105 and 106:
to high inrush current causes a con
Page 107 and 108:
(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
Page 115 and 116:
Figure 4.17: Resultant 3φ Capacito
Page 117 and 118:
Page 119 and 120:
Figure 4.21: Resultant line-to-line
Page 121 and 122:
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
Page 127 and 128:
+1.6 +0.66 Thyristor Voltage (kV) -
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+1.5 +1.0 Capacitor Voltage (kV) +0
Page 131 and 132:
+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
Page 151 and 152:
APPENDIX B DISTINCTIVE CURVES OF TH
Page 153 and 154:
135 Figure B.2: Stored charge and r
Page 155 and 156:
APPENDIX C DETAILS OF THE CONTROL C
Page 157 and 158:
139 Figure C.2: P-CAD 2002 Schemati
Page 159 and 160:
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
Page 171 and 172:
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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