Research On Adaptive Reclosure Using Sensitive Model Parameter Identification

It is well known that autoreclosure technique is an effective action to improve stability and reliability of power system. However, the conventional autoreclosure techniques usually using a fixed time whether in transient faults or permanent faults, may aggravate potential damage to the system and the main power equipments for unsuccessful reclosure in the case of a permanent fault or an arcing transient fault. At the same time, operating overvoltage is produced in the process of tripping, which may bring a serious threat to the safe and stable operation of the important equipment in power system even than that caused by unsuccessful single-phase reclosing. Thus, it is significant to study on autoreclosure aiming to distinguish permanent and transient faults for transmission lines. Moreover, it is important to study on non-fault detection for reclosure techniques aiming to lower blindness reclosing in the case of a permanent or an insufficient transient fault an improve the security and reliability of power system.In view of the fact that the method based on model identification in time-domain method has more excellent performance and applicability than the method based on power frequency, which is not affected by electrical quantities " beat frequency " characteristics, this paper put forward an improved faults nature detection scheme for three-phase reclosure based on mode parameter identification and a novel non-fault discrimination method based on model recognition before three-phase reclosing for transmission lines with shunt reactors. There are two ideas and thoughts as following.1) The method considers the π-type equivalent model in the arc extinct transient fault as the reference to build permanent faults nature identification criterions, which are based on parameters recognition such as the inductances of shunt reactors, neutral reactor and the inductance combined by the former etc. Moreover, on the basis of that, the performance and applicability and sensitivity etc. are analyzed and optimized. For the criterions use the model parameters recognition, which is affected by the direct component and low frequency component etc., the schemes are applicable to the fast reclosure on the transmission lines with shunt reactors.2) The scheme uses the π-type equivalent model in the arc extinct transient faults as the prototype. Either in transient fault without arc or in arcing transient faults even permanent faults, it uses current of shunt reactors with high precision and calculates the sums of the mode component of shunt reactors currents and capacitive currents at both terminals based on the reference. According to phase-model transformation matrix, the formula is developed for summing the currents of shunt reactors and capacitive currents for three-phase to implement non-fault detection. It is noted that the presented non-fault detection is independent on fault phase selection and is able to detect non-fault reliably before three-phase reclosing, which is helpful to avoid blind reclosing and identify the fault phase for arcing faults especially serious permanent faults.In order to verify the validity and correctness of the criterion referred to in this article, using ATP software to simulate and analyze combined with MATLAB. ATP simulation using real transmission line parameter to build simulation models, a variety of simulations under different fault conditions verify the correctness and effectiveness of criterions, which lays a strong theoretical foundation for practical engineering application.