控制电缆烧损事故之分析改善和预防对策.ppt

中正--電力品質實驗室 * 中正--電力品質實驗室 Model 1: a single-phase SVC that includes a fixed capacitor in parallel with the TCR. The power system is represented by its Thévenin equivalent. s is the switching function Model 2: two anti-parallel thyristors are replaced by two time-varying resistors, Rt1 and Rt2. An equivalent resistance, RT, is then used to represent these resistors. RT becomes zero when any of the thyristors is conducted 中正--電力品質實驗室 中正--電力品質實驗室 the first term specifies the characteristic harmonics from a p-pulse converter and the second term represents sidebands of each of the dominant characteristic harmonics, which may not be integers 中正--電力品質實驗室 * 中正--電力品質實驗室 * 中正--電力品質實驗室 * 中正--電力品質實驗室 * 中正--電力品質實驗室 The model is similar to that of the synchronous machines as we previously talked about. 中正--電力品質實驗室 For induction motor, we can generally model it from 2 aspects: under balanced condition and unbalanced condition 中正--電力品質實驗室 * 中正--電力品質實驗室 * 中正--電力品質實驗室 * 中正--電力品質實驗室 中正--電力品質實驗室 * 中正--電力品質實驗室 Figure (a) shows the typical voltage-current characteristics of the furnace arc Figure (b) shows the resulting arc current and voltage when a sinusoidal source supplies the furnace The last figure shows the typical spectrum of arc furnace current. It can be seen that besides integer harmonics, the arc furnace currents are also rich in inter-harmonics. 中正--電力品質實驗室 Although an arc furnace can be modeled simply as an inductor in series with a resistor, many complex models were proposed to more precisely represent its characteristics and to study its impacts on power systems. Here is the list of 7 models to be covered here. Next, we will briefly introduce each one of them. 中正--電力品質實驗室 The simplified V-I characteristics can be modeled into the circuit as shown. Several characteristics are listed. 中正--電力品質實驗室 * 中正--電力品質實驗室 * 中正--電力品質實驗室 Deterministic: Dl is the maximum variation of arc length, and ? is an angular frequency in the range of 0.5 to 25 Hz, which is the popular flicker