Showing 11 results for Kazemi
A. Kazemi, A. Badri, S. Jadid,
Volume 1, Issue 4 (October 2005)
Abstract
In this paper, two vector control systems for investigating the performance of
Static Synchronous Series Compensators (SSSC) in steady state conditions are presented
that are based on famous d-q axis theory. The workability of proposed method to simplify
the SSSC mathematical expressions is shown. The performance of SSSC with two different
vector controllers, first based on d-q line currents(indirect control) and the second a
heuristic vector control based on real and reactive line powers (direct control), are
investigated through simulation. It is found that the new introduced direct control produces
better performance in controlling AC power system. Finally the simulation results of an
elementary two-machine system with SSSC in different cases are investigated.
A. Kazemi, Sh. Jadid, H. Andami,
Volume 3, Issue 1 (April 2007)
Abstract
Transmission loss allocation in very large networks with multiple interconnected
areas or countries is investigated in this paper. The main contribution is to propose a
method to calculate the amount of losses due to activity of each participant in the multi area
markets. Pricing of cross-border trades in Multi area systems is often difficult since
individual countries may use incompatible internal transmission pricing regimes, and they
are usually unwilling to disclose any sensitive information about their own systems.
A new methodology based on the loss formula concept for allocating electric losses to
generators and loads is presented in this paper. The only data required are the power flows
and characteristics of tie-lines and PV Ward equivalent model of area networks from border
nodes point of view. Proposed methodology is tested on the IEEE 118 node network which
is divided into three areas, each with a different internal transmission pricing methodology.
In the proposed methodology no information is required about individual loads, generations
or detailed internal networks. It is also shown to be simple, transparent and very fast and it
can deal effectively with multiple pricing policies.
B. Ghafary, F.d. Kashani, E. Kazemian,
Volume 9, Issue 1 (March 2013)
Abstract
The effects of aberration on the Bit-Error-Rate (BER) and reliability of free- space optical (FSO) communication links are investigated. Based on aberrated divergent rectangular partially coherent flat-topped beam formula on the receiver plane and considering the atmosphere losses due to absorption and scattering, numerical values for Power In Bucket (PIB), Signal to Noise Ratio (SNR) and BER are calculated. Using above mentioned values, the effects of source parameters on link reliability is described. The results are illustrated by graphs obtained by calculation and simulation.
F Dabbagh Kashani, M R Hedayati Rad, E Kazemian,
Volume 9, Issue 4 (December 2013)
Abstract
Study of the beam propagation behavior through oceanic media is a challenging subject. In this paper, based on generalized Collins integral, the mean irradiance profile of Gaussian laser beam propagation through ocean is investigated. Power In Special Bucket (PIB) is calculated. Using analytical expressions and calculating seawater transmission, the effects of absorption and scattering on beam propagation are studied. Based on these formulae, propagation in ocean and atmosphere are compared. The effects of some optical and environmental specifications, such as divergence angle and chlorophyll concentration in seawater on beam propagation by using mean irradiance, PIB and analytical formula of oceanic transmission are studied. The calculated results are shown graphically.
F. Dabbagh Kashani, M. R. Hedayati Rad, E. Kazemian, A. Kahrizi, M. R. Mahzoun,
Volume 10, Issue 1 (March 2014)
Abstract
In this paper, we investigate the effects of auto-tracking subsystem together with different beam divergences on SNR, BER and stability of FSO communication links. For this purpose we compute the values of power, SNR and BER on receiver, based on analytic formula of Gaussian beam on receiver plane. In this computation the atmospheric effects including absorption, scattering and turbulence are considered. Using mentioned computed values, the laser link stability and its reliability in presence of auto-tracking subsystems are evaluated. The results of simulation and computation are shown with the help of figures and tables.
S. Heshmatian, D. Arab Khaburi, M. Khosravi, A. Kazemi,
Volume 14, Issue 1 (March 2018)
Abstract
Wind energy is one of the most promising renewable energy resources. Due to instantaneous variations of the wind speed, an appropriate Maximum Power Point Tracking (MPPT) method is necessary for maximizing the captured energy from the wind at different speeds. The most commonly used MPPT algorithms are Tip Speed Ratio (TSR), Power Signal Feedback (PSF), Optimal Torque Control (OTC) and Hill Climbing Search (HCS). Each of these algorithms has some advantages and also some major drawbacks. In this paper, a novel hybrid MPPT algorithm is proposed which modifies the conventional methods in a way that eliminates their drawbacks and yields an improved performance. This proposed algorithm is faster in tracking the maximum power point and provides a more accurate response with lower steady state error. Moreover, it presents a great performance under conditions with intensive wind speed variations. The studied Wind Energy Conversion System (WECS) consists of a Permanent Magnet Synchronous Generator (PMSG) connected to the dc link through a Pulse-Width Modulated (PWM) rectifier. The proposed algorithm and the conventional methods are applied to this WECS and their performances are compared using the simulation results. These results approve the satisfactory performance of the proposed algorithm and its notable advantages over the conventional methods.
Z. Kazemi, A. A. Safavi,
Volume 16, Issue 3 (September 2020)
Abstract
Kalman filtering has been widely considered for dynamic state estimation in smart grids. Despite its unique merits, the Kalman Filter (KF)-based dynamic state estimation can be undesirably influenced by cyber adversarial attacks that can potentially be launched against the communication links in the Cyber-Physical System (CPS). To enhance the security of KF-based state estimation, in this paper, the basic KF-based method is enhanced by incorporating the dynamics of the attack vector into the system state-space model using an observer-based preprocessing stage. The proposed technique not only immunizes the state estimation against cyber-attacks but also effectively handles the issues relevant to the modeling uncertainties and measurement noises/errors. The effectiveness of the proposed approach is demonstrated by detailed mathematical analysis and testing it on two well-known IEEE cyber-physical test systems.
M. Keshavarz, A. Doroudi, M. H. Kazemi, N. Mahdian Dehkordi,
Volume 17, Issue 2 (June 2021)
Abstract
The droop control strategy is the most common approach for microgrids control but its application is limited due to frequency deviation following a load change. Complementary control strategy has then been proposed to solve the problem using a communication network. However, under this strategy, regular loads profile produces a continuous change of output power of all distributed generators (DGs) and their generation changes seem to be permanent. This also causes continuous data exchange between DGs through communication links. This paper shows the possibility of adapting the droop/isochronous control methodology used by synchronous generators in conventional power systems to provide frequency control and power balance to inverter-based distributed generation power systems. To this end, this paper presents a centralized complementary control framework for the management of power-sharing and sustaining frequency in its nominal range in microgrids using a hybrid droop-isochronous control system. The proposed method is event-triggered based and communication between DGs is only needed when the output power of the isochronous generator exceeds its power limits. The method provides an efficient and reliable control system and has a simple concept, easy, and cost-effective implementation. Simulations in MATLAB/SimPower are performed on a typical microgrid under various conditions to evaluate the performance of the proposed controller.
A. Ataee, S. J. Kazemitabar,
Volume 19, Issue 1 (March 2023)
Abstract
We propose a real-time Yolov5 based deep convolutional neural network for detecting ships in the video. We begin with two famous publicly available SeaShip datasets each having around 9,000 images. We then supplement that with our self-collected dataset containing another thirteen thousand images. These images were labeled in six different classes, including passenger ships, military ships, cargo ships, container ships, fishing boats, and crane ships. The results confirm that Yolov5s can classify the ship's position in real-time from 135 frames per second videos with 99 % precision.
Fatemeh Zare-Mirakabad, Mohammad Hosein Kazemi, Aref Doroudi,
Volume 19, Issue 3 (September 2023)
Abstract
This paper proposes a robust H ∞ -LMI-based primary controller using the Linear Parameter Varying (LPV) modeling for an AC islanded Micro-Grid (IMG). The proposed controller can regulate the frequency and voltage of the IMG under various scenarios, such as load changes, faults, and reconfigurations. Unlike most previous studies that neglected the nonlinearity and uncertainty of the system, this paper represents the system dynamics as a polytopic LPV model in the novel primary control structure. The proposed method computes a state-feedback control by solving the corresponding Linear Matrix Inequalities (LMIs) based on H ∞ performance and stability criteria. The robust primary control is applied to a test IMG in the SIM-POWER environment of MATLAB and evaluated under different scenarios. The simulation results demonstrate the effectiveness and efficiency of the proposed method in maintaining the stability of the frequency and voltage of the IMG.
Robab Kazemi, Zohreh Asadollahzadeh-Zia, Reza Masoumi,
Volume 19, Issue 4 (December 2023)
Abstract
In this work, a broadband dual-channel differential phase shifter is developed with a small phase deviation across a wide frequency range. The design consists of two main lines for 45° and 90° phase shifts, along with a reference line. A prototype is fabricated and measured to validate the performance of the design. Phase shifts of 45° ± 5° and 90° ± 5° over a frequency range of 1.26 GHz - 4 GHz (bandwidth of 104%) are achieved from the channels. The transmission losses of the three lines are less than 0.35 dB and the isolation between the adjacent ports is better than 20 dB. The area of this dual-channel differential phase shifter is 
(14.7 mm × 66.15 mm), where 
is the guided wavelength at the center frequency.
