Saturday, March 12, 2011

ABSTRACT, Protection on Transmission Overhead Line Used Distance Relay

   1.   Jafarian, P., Sanaye-Pasand, M., 2011. Weighted least error squares based variable window phasor estimator for distance relaying application. Iet Generation Transmission & Distribution 5, 298-306.
Abstract: This study presents an adaptive data window algorithm for fast and accurate signal phasor estimation. The proposed approach is based on weighted least error squares algorithm as well as variable data window estimation technique. An adaptive model is used for the input signal during the two stages. The first stage is considered to accelerate the relay first zone operation. This is done through applying a forgetting factor in the cost function computation, by which the effect of older samples on the estimation is reduced to decrease the initial inertia of the phasor estimator. The second stage starts one cycle after occurrence of the fault. This algorithm is used to improve the estimation accuracy and helps to obtain better estimation for the fault location. To verify the performance of the proposed algorithm, various simulation studies are carried out. The algorithm is also evaluated using some field data recorded from a high-voltage transmission system. The obtained results confirm accurate, fast and reliable response of the proposed algorithm. It not only accelerates the relay operation but also improves the digital filters' capability of reducing the estimation error because of power system frequency deviation, harmonics, inter-harmonics and decaying dc component

Tuesday, March 1, 2011

ABSTRACT - Expert System Fault Transmission Overhead Line Protection System


   1.   Guo, W.X., Wen, F.S., Liao, Z.W., Wei, L.H., Xin, J.B., 2010. An Analytic Model-Based Approach for Power System Alarm Processing Employing Temporal Constraint Network. Ieee Transactions on Power Delivery 25, 2435-2447.

Abstract: The alarm-processing problem is to interpret a large number of alarms under stress conditions, such as faults or disturbances, by providing summarized and synthesized information instead of a flood of raw alarm data. Alarm timestamps represent the temporal relationship among event occurrences and consist of rich and useful information for alarm processing. However, the temporal information has not been well utilized in existing alarm-processing methods. The temporal constraint network (TCN) is a type of directed acyclic graph suitable for representing temporal logics. Based on TCN, a new analytic model is developed for alarm processing with temporal information taken into account. Three major modules are included in the developed approach or alarm processor (i.e., alarm selection, event analysis, and result evaluation). In the alarm selection module, reported alarms are divided into related