چكيده به لاتين
Abstract:
Statistics show that 80-90% of faults on transmission lines are of arcing (or transient) nature, which are mostly single phase to earth type. For such faults, by de-energising the faulted phase for the time enough the arcing to be cleared, a successful reclosing can be achieved. During a single phase auto-reclosing transmission lines can still pass more than 50% of their nominal power, hence improving the system reliability and transient stability.
In the beginning of this dissertation concept and literature of the adaptive single phase auto-reclosing is explained. Then the details of modelling of the simulated power system is presented in chapter 3. In the following, the reference method of this dissertation is studied and analysed. The preliminary results of the reference method was not successful then in order to achieve accurate results, appropriate changes in the reference method has been applied. The main problems of the reference method can be summarized as follows. Inappropriate threshold levels, absence of appropriate margin to determine threshold level, variation of assumptions of reference method with power system condition changing, influence of length of deriving window on results, unsuitable sampling frequency and lack of superior logic to coordinate different parts of algorithm.
In the fallowing the new algorithm to detect secondary arc extinction is presented. First algorithm presents a non-communication based method which using the behaviour pattern of the faulted phase voltage magnitude measured at the near end of the line. The second algorithm is based on first derivation of faulted phase voltage magnitude. These methods does not need a predefined threshold level and the algorithm uses low sampling frequency and is simple and fast. The algorithm can be applied on all transmission line configurations (transposed or untransposed) with different levels of reactive power compensation. To avoid the mal operation of the algorithms the concept of algorithm starting time is identified and calculated adaptively.
Keywords: Adaptive single phase auto-reclosing,Transmision line Secondary arc, Power system protection, Transient fault
