نشریه مهندسی برق و مهندسی کامپیوتر ایران
سال هجدهم شماره 3 (پیاپی 57، پاییز 1399)

This paper proposes a preventive and probabilistic–possibilistic framework for day-ahead scheduling of Electric Vehicles (EVs) parking lot and distributed generation in a microgrid. The suggested scheduling is performed in normal and emergency conditions when a natural phenomenon appears and the microgrid is disconnected from the upstream network. Furthermore, the uncertainty of EVs number in a parking lot is considered by Z-number as a probabilistic-possibilistic model. Moreover, the uncertainties of photovoltaic units generation, wind turbine output power, market price, and load demand are modeled by Monte Carlo as a probabilistic method. Furthermore, natural phenomena occurrences are modeled by considering multifarious scenarios according to when the phenomenon unfolds and how much it takes. In the suggested framework, the operation of parking lots is based on the uncertainty and EVs charging/discharging schedule. The operational cost in normal condition and load shedding cost in addition to operational cost are considered as the objective functions of the proposed structure. To evaluate the performance of the suggested structure, the modified 33-bus IEEE distribution network is employed.

The deposited pollution on the insulaters surface in overhead Transmission Lines and also its characteristic is one of the effective factors on insulators electrical behavior. The pollution on insulators surface is Non-uniform due to the wind direction. So, less contamination is in the same direction wind. Also, the pollution is different throughout the insulators length and in near high and low voltage electrodes. Therefore, the deposited contamination on insulators is non-uniform and can be considered two forms of longitudinal and Fan-shaped non-uniform pollutions. In this paper, the influence of uniform pollution and also the effect of three states for pollution expansion (%15, %25, %35) and four states non-uniform contamination degree (1.5, 3, 6, 13) with longitudinal and Fan-shaped, under different humidities, on the flashover voltage different 20 kV silicon rubber insulators, have been studied. According to the obtained results from laboratory tests, the increase of non-uniformity contamination degree has significant effect on the behavior of the insulators under different non-uniform pollution, so that the flashover voltage has decreased between 8.8 to 42.21 percent in all the insulators.

Future cellular networks 5G+ promise high data rates, ubiquitous services everywhere and flexibility. Cooperative airborne relay networks (CARNs) is a promising system architecture that enables network coverage extension and reliability enhancement. This article determined the optimum relay location and allocate optimal power to minimize the average symbol error rate (ASER) of an aerial platform CRS with amplify-and-forward relaying protocol (AF-CRS) in the Nakagami-m fading channel. To achieve this goal, the ASER for the AF-CRS in the Nakagami-m channel for different modulations is calculated firstly. Then, we consider three scenarios. First, the optimal location of the AF relay with a given power allocation for the source and relay is determined. Second, the problem of optimizing power allocation for different relay locations is solved. Eventually, an algorithm for joint optimizing the power-location that leads to more efficient system operation is proposed. Also, we investigate the effect of the path-loss exponent, channel fading parameter, and relay altitude on the optimal relay location in the CARS. Finally, Simulations and numerical results are presented, that confirm the theoretical achievements and simulations show a more than 1 dB gain for the optimized system versus the non-optimized system.

In power systems operation, interruptions occur due to various reasons such as faults and inadequacy of generation. Load shedding allocation with respect to operation costs and security, customers’ type and their behavior is the main challenge of this paper. In this research a new procedure for load shedding allocation with respect to the “load shedding history” of each customer is presented. In this research a new coefficient, called endurance coefficient, is introduced. The customers declare their dependency to electricity via sending their endurance coefficients to the power system operator (ISO).A new method is proposed in this paper in which the customers get paid according to the mentioned coefficient, if load shedding occurs. For validation of the proposed method, different scenarios on IEEE RTS 24-bus test grid is studied and numerical results show effectiveness of the proposed method.

This paper deals with the performance investigation and control of a combined wind-microturbine generation system at off-grid and stand-alone applications. As the novelty, in this paper, the wind turbine does not always work at the MPPT mode, and depending on the available wind power and load demand, two operation modes for the wind turbine are defined: power control mode (MPPT mode) and voltage control mode. At the conditions that the available wind power is less than the load demand, the wind turbine operates at the MPPT mode and microtubule provides the rest of the load power. Once the available wind power goes beyond the load demand, the microturbine can not absorb the additional power, and wind turbine works at load following mode. In this mode, the wind turbine power is less than the available wind power and is identical to the load demand, and the microturbine power is negligible. At the end, by performing simulations at the Matlab-Simulink environment, performance of the study system at different operating conditions is investigated.

Due to the increasing use of compressors in the industry, it is important to determine a mathematical model for the compressor to design a control system, analysis and simulation of the computer. Also, in recent years, smart modeling such as neural network and fuzzy network have been considered by researchers for their more realistic performance, and their types have been used for modeling. Smart methods have high capability to communicate between input and output data. In this paper, modeling of K-250 compressor at Isfahan smelter company based on smart models of fuzzy neural network is presented. The Nonlinear Auto Regressive With exogenous input (Narx) and hierarchical fuzzy network are presented. For modeling, the system has been tested and the input and output data of the compressor using compressor sensors and image processing are used to convert the data into the required data in the modeling, then the above algorithms of the compressor model will be achieved with the help of software, MATLAB. The results of modeling Which NARX performed better than hierarchical fuzzy. Among the two models presented in this paper, the NARX model shows a better response than the hierarchical fuzzy network in all cases and in all aspects of the performance criteria.

Ink-jet printing technology is one of the most promising printing techniques enabling fabrication of conductive patterns in a one-step and direct process. In this study, a microwave transmission line is fabricated on RO4003C substrate using water-based reactive inks and ink-jet printing technique. The fabricated transmission line structure includes an ink-jet printed silver line, a dielectric layer, and a continuous metallic ground plate. The conductivity of the printed line is measured using Four-point probe method. The electromagnetic wave absorption rate of the printed transmission line is simulated according to the measured conductivity, which proves a good agreement with the measured absorption rate at S band (2-4 GHz frequency range).