Introduction to Static Var Compensator.pdf

To phase a of the svc step down transformer ଵ ? ?

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To phase A of the SVC step-down transformer ܺ ௅ଵ,்஼ோ ܺ ௅ଶ,்஼ோ ܺ ௅ଷ,்஼ோ ܳ ܳ ܳ ܳ ܳ ܳ ܧ ்஼ோ ܫ ்஼ோ To phase C of the SVC step-down transformer To phase B of the SVC step-down transformer
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Main Components of a Static Var Compensator (SVC) Discussion Static Var Compensator (SVC) 15 Figure 15. RMS value of current ࢀ࡯ࡾ,૚ࢌ and reactive power ࢀ࡯ࡾ in the TCR as a function of the firing angle of the thyristor controller. The above figure shows that, when the firing angle ߙ of the thyristors in a TCR is set to a value between 0° and 90°, the rms value of the current ܫ ்஼ோ,ଵ௙ and the reactive power ܳ ்஼ோ are maximal. This is due to the inductive nature of the load connected to the thyristors (i.e., the inductors of the TCR). As the firing angle ߙ of the thyristors in the TCR increases above 90°, the waveform of the current ܫ ்஼ோ flowing through each inductor becomes more and more chopped. Because of this, the rms value of the current ܫ ்஼ோ,ଵ௙ and the amount of reactive power ܳ ்஼ோ decrease rapidly as the firing angle ߙ of the thyristors increases. Thus, by setting the firing angle ߙ of the thyristors to any value between 90° and 180°, it is possible to precisely adjust the rms value of the current ܫ ்஼ோ,ଵ௙ and, consequently, the amount of reactive power ܳ ்஼ோ absorbed by each leg of the TCR. Harmonics generated in the current I TCR flowing in each inductor of a TCR When the firing angle ߙ of the thyristors in a TCR is set to a value between 0° and 90°, the rms value of the harmonic components in the current ܫ ்஼ோ flowing in each inductor of the TCR is minimal. This is due to the fact that, as mentioned in the previous subsection, the rms value of current ܫ ்஼ோ,ଵ௙ is maximal when the firing angle ߙ of the thyristors is set to a value between 0° and 90°, since the waveform of the current ܫ ்஼ோ flowing in each inductor of the TCR remains a sine wave (i.e., the current waveform is not chopped). Consequently, no harmonic components are generated in the current ܫ ்஼ோ . When the firing angle ߙ of the thyristors in a TCR is higher than 90°, however, the waveform of the current ܫ ்஼ோ flowing in each inductor of the TCR becomes chopped. Because of this, harmonic components are generated in the current ܫ ்஼ோ . The rms value of each of these harmonic components depends on the firing angle ߙ of the thyristors. Curves of the rms value of the first seven Reactive power ܳ ்஼ோ (% of nominal value) Firing angle ߙ of the thyristors (°) RMS value of current ܫ ்஼ோ,ଵ௙ (% of nominal rms value) 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 0 10 20 30 40 50 60 70 80 90 100
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Main Components of a Static Var Compensator (SVC) Discussion 16 Static Var Compensator (SVC) harmonic components in the current ܫ ்஼ோ flowing in each inductor of a TCR as a function of the firing angle ߙ of the thyristors are plotted on the graph shown in Figure 16. Note that only odd harmonic components are produced because the
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  • One '14
  • Electric power transmission, AC power, TCR, Static VAR compensator

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