Journal of Modeling and Simulation in Electrical and Electronics Engineering
Volume:1 Issue: 2, Spring 2021

In this paper an optimal trajectory control strategy is presented for single and multiple unmanned aerial vehicles (UAVs) equipped with received signal strength (RSS) sensors to localize a stationary RF source. The RSS at each UAV is observed in specified time instances. Due to the additive Gaussian noise caused by the non-line of sight (NLOS) propagation condition the location of the source is estimated using the extended Kalman filter (EKF). The objective is to determine the waypoints of the UAVs that minimize the source location uncertainty. The determinant of the Fisher information matrix (FIM) which is inversely proportional to estimation variance is applied to generate UAVs’ trajectories. The FIM is approximated at successive waypoints according to the estimated source location. To compensate the lack of adequate number of sensors when applying one or two UAVs the previous information is included in FIM calculations. The effectiveness of the proposed approach is depicted in simulation examples.

Microgrids are practical views of integration of distributed generations (DGs) into distribution systems. In this regard, utilizing appropriate technologies and accurate recognition of energy generation and storage systems, as well as optimal scheduling for these resources are of the paramount importance in microgrids. Therefore, connection of DG resources and storages to the grid in the form of virtual power plant in order to increase efficiency and owners’ interest has attracted significant attention of researchers and distribution network operators. This research presents a model for optimal day-ahead scheduling of heat-power generation units in a multi-zonal virtual power plant (VPP). This VPP includes a number of combined heat-power generations, distribution network loads, and electrical vehicles with smart charging as well as energy storages. In order to approach the reality of distribution systems, uncertainty related to behavior of electrical vehicles was modeled with Monte-Carlo simulation while uncertainties of generation and electrical/thermal loads were modeled using a probabilistic method. Matlab software and swarm robotics search & rescue (SRSR) has been used as an optimization tool in this paper. The results confirmed the effectiveness of the proposed method.

Market power is a result of anti-competitive behaviors in oligopoly power markets. Ex-ante indices evaluate the potential of market power through the capacity analysis of participants. In this study, structural indices are modified, and new indices are proposed to overcome the shortcoming of market power assessment in electricity markets. In the proposed indices, two types of assessment are considered as deterministic and probabilistic terms. These indices evaluate the incentive of each participant (supplier) to exercise market power. The probabilistic term of these indices considers the stochastic and uncertain nature of renewable energy resources. The Monte Carlo method (MCM) is used for modeling the uncertainty of renewable resources. The impact of each participant's transmission constraints, size, generation cost, and geographical differences in market power assessment are considered. Examination of the results taken from an IEEE 30-bus test system confirms the proposed indices' effectiveness in assessing market power potential.

This paper presents a modified nonabsorptive radar cross-section (RCS) reducer based on previous reports. The design is a flat 4×4 chessboard, followed by two upper and lower dielectrics with the same relative permittivity and thickness. The lower dielectric is metal-backed. The incident wave to the surface of the upper dielectric penetrates through the structure. Some parts of the incident wave is reflected back by the black (metal) sections of the chessboard in the middle, while the remaining parts of the wave penetrates further in the lower dielectric until it is totally reflected by the ground plane. The relative permittivity and dielectric thicknesses are computed analytically to make a 180° phase difference between the two reflected waves. This results in destructive interference and makes a null in the expected angle of reflection. The theory of operation is deduced generally for any angle of incidence as well as both principal polarizations. First, the designing procedure is done with MATLAB, then the practical design is simulated with Ansys HFSS13 and finally, it is fabricated and its monostatic RCS reduction property is measured experimentally. At least 10dB RCS reduction compared to a metal plate of the same size is guaranteed from 8.5 to 17.5 GHz for normal incidence.

Speeding up the system is one of the basic challenges in the real-world applications of Face Recognition (FR), whereas reducing the computational complexity can significantly increase the speed of the system. In recent years, many face recognition methods have been proposed but few of them give attention to this issue. Accordingly, in this article, we take the axis-symmetrical property of faces as a novel idea to speed up the face recognition algorithm as well as to reduce the computational complexity. Taking the axis-symmetrical property of faces leads us to use half of the face image. Proposing a face recognition system using Hidden Markov Model (HMM) as a classifier, we use the Singular Value Decomposition (SVD) to build the observation vectors. Evaluated results of the proposed system on Yale and Faces94 datasets show that the proposed system can achieve a satisfactory recognition rate with a higher speed.

Inverters have evolved significantly in the last decade as a key component in electrical systems. Improving the performance of the inverters is a challenge, leading to many types of researches on topologies and control schemes. Multi-level voltage source inverters are suitable structures to achieve high-power and high-quality output waveforms. Till now, wide studies have been conducted in the field of multi-level inverters used in high-power and voltage applications, which have attracted attention due to their advantages, including less harmonic distortion of output waveforms, less tension of switch voltages, and low electromagnetic interference. In this paper, a sinusoidal pulse width modulation (SPWM) cascade full-bridge single-phase 7-level inverter with phase shift modulation is designed using a suitable voltage control with low capacitance for asymmetric condition and its performance is investigated. The performance of the proposed inverter is investigated under different operational conditions through simulations in MATLAB. Besides, for more investigation, an experimental sample of this inverter is constructed and the practical results are presented. The experimental results show that the output harmonic current of the inverter under symmetric performance of the output current is 1.51%. Although this THD is higher than the value obtained in the simulation results, it complies with the ISIRI 11859 standards for the current THD, which indicates that a THD less than 5% is acceptable.

The grounding system of the step-up transformers is one of the main issues in power plants especially in large industries such as petrochemicals and refineries. In addition to the effects of this system on the fault currents and voltages magnitude, the dynamic behavior of the generators is also affected at fault duration by the neutral grounding impedance. In this paper, at first analytical expressions of some parameters such as current, active power, and power angle of the generator are derived for a phase to ground fault. Then the validation of derived equations is examined by simulation of a real power plant located in a petrochemical complex. At last, these equations will be used to define a new graphic pattern of fault which is the locus of the active power vs short circuit current. The shape of this pattern is related to the type of the fault and grounding impedance. Hence it can be used to identify some faults in the power systems.