Showing 7 results for Jamali
F. Namdari, S. Jamali, P. A. Crossley,
Volume 1, Issue 3 (July 2005)
Abstract
Current differential based wide area protection (WAP) has recently been
proposed as a technique to increase the reliability of protection systems. It increases system
stability and can prevent large contingencies such as cascading outages and blackouts. This
paper describes how power differential protection (PDP) can be used within a WAP and
shows that the algorithm operates correctly for all types of system faults whilst preventing
unwanted tripping, even if the data has been distorted by CT saturation or by data
mismatches caused by delays in the WAP data collection system.
The PDP algorithm has been simulated and tested on an Iranian 400kV transmission line
during different fault and system operating conditions. The proposed operating logic and
the PDP algorithm were also evaluated using simulation studies based on the Northern
Ireland Electricity (NIE) 275 kV network. The results presented illustrate the validity of the
proposed protection.
H. Shateri, S. Jamali,
Volume 2, Issue 3 (October 2006)
Abstract
This paper presents the effects of instrument transformers connection points on
the measured impedance by distance relays in the presence of Flexible Alternating Current
Transmission System (FACTS) devices with series connected branch. Distance relay
tripping characteristic itself depends on the power system structural conditions, pre-fault
operational conditions, and especially the ground fault resistance. The structural and
controlling parameters of FACTS devices as well as the connection points of instrument
transformers affect the ideal tripping characteristic of distance relay. This paper presents a
general set of equations to evaluate the measured impedance at the relaying point for a
general model of FACTS devices to consider different affecting parameters.
S. Jamali , A. Parham,
Volume 4, Issue 3 (July 2008)
Abstract
This paper presents an algorithm for adaptive determination of the dead time
during transient arcing faults and blocking automatic reclosing during permanent faults on
overhead transmission lines. The discrimination between transient and permanent faults is
made by the zero sequence voltage measured at the relay point. If the fault is recognised as
an arcing one, then the third harmonic of the zero sequence voltage is used to evaluate the
extinction time of the secondary arc and to initiate reclosing signal. The significant
advantage of this algorithm is that it uses an adaptive threshold level and therefore its
performance is independent of fault location, line parameters and the system operating
conditions. The proposed algorithm has been successfully tested under a variety of fault
locations and load angles on a 400KV overhead line using Electro-Magnetic Transient
Program (EMTP). The test results validate the algorithm ability in determining the
secondary arc extinction time during transient faults as well as blocking unsuccessful
automatic reclosing during permanent faults.
M. Jamali, M. Mirzaie, S. A. Gholamian,
Volume 7, Issue 3 (September 2011)
Abstract
The phenomenon of magnetizing inrush is a transient condition, which occurs primarily when a transformer is energized. The magnitude of inrush current may be as high as ten times or more times of transformer rated current that causes malfunction of protection system. So, for safe running of a transformer, it is necessary to distinguish inrush current from fault currents. In this paper, an equivalent instantaneous inductance (EII) technique is used to discriminate inrush current from fault currents. For this purpose, a three-phase power transformer has been simulated in Maxwell software that is based on finite elements. This three-phase power transformer has been used to simulate different conditions. Then, the results have been used as inputs in MATLAB program to implement the equivalent instantaneous inductance technique. The results show that in the case of inrush current, the equivalent instantaneous inductance has a drastic variation, while it is almost constant in the cases of fault conditions.
H. Jamali Rad, B. Abolhassani, M. Abdizadeh,
Volume 8, Issue 3 (September 2012)
Abstract
In this paper, we study the problem of power efficient tracking interval management for distributed target tracking wireless sensor networks (WSNs). We first analyze the performance of a distributed target tracking network with one moving object, using a quantitative mathematical analysis. We show that previously proposed algorithms are efficient only for constant average velocity objects however, they do not ensure an optimal performance for moving objects with acceleration. Towards an optimal performance, first, we derive a mathematical equation for the estimation of the minimal achievable power consumption by an optimal adaptive tracking interval management algorithm. This can be used as a benchmark for energy efficiency of these adaptive algorithms. Second, we describe our recently proposed energy efficient blind adaptive time interval management algorithm called Adaptive Hill Climbing (AHC) in more detail and explain how it tries to get closer to the derived optimal performance. Finally, we provide a comprehensive performance evaluation for the recent similar adaptive time interval management algorithms using computer simulations. The simulation results show that using the AHC algorithm, the network has a very good performance with the added advantage of getting 9 % closer to the calculated minimal achievable power consumption compared with that of the best previously proposed energy efficient adaptive time interval management algorithm.
A. Bahmanyar, H. Borhani-Bahabadi, S. Jamali,
Volume 16, Issue 3 (September 2020)
Abstract
To realize the self-healing concept of smart grids, an accurate and reliable fault locator is a prerequisite. This paper presents a new fault location method for active power distribution networks which is based on measured voltage sag and use of whale optimization algorithm (WOA). The fault induced voltage sag depends on the fault location and resistance. Therefore, the fault location can be found by investigation of voltage sags recorded throughout the distribution network. However, this approach requires a considerable effort to check all possible fault location and resistance values to find the correct solution. In this paper, an improved version of the WOA is proposed to find the fault location as an optimization problem. This optimization technique employs a number of agents (whales) to search for a bunch of fish in the optimal position, i.e. the fault location and its resistance. The method is applicable to different distribution network configurations. The accuracy of the method is verified by simulation tests on a distribution feeder and comparative analysis with two other deterministic methods reported in the literature. The simulation results indicate that the proposed optimized method gives more accurate and reliable results.
M. Najjarpour, B. Tousi, S. Jamali,
Volume 18, Issue 4 (December 2022)
Abstract
Optimal power flow is an essential tool in the study of power systems. Distributed generation sources increase network uncertainties due to their random behavior, so the optimal power flow is no longer responsive and the probabilistic optimal power flow must be used. This paper presents a probabilistic optimal power flow algorithm using the Taguchi method based on orthogonal arrays and genetic algorithms. This method can apply correlations and is validated by simulation experiments in the IEEE 30-bus network. The test results of this method are compared with the Monte Carlo simulation results and the two-point estimation method. The purpose of this paper is to reduce the losses of the entire IEEE 30-bus network. The accuracy and efficiency of the proposed Taguchi correlation method and the genetic algorithm are confirmed by comparison with the Monte Carlo simulation and the two-point estimation method. Finally, with this method, we see a reduction of 5.5 MW of losses.
