فصلنامه مهندسی و مدیریت انرژی
سال چهاردهم شماره 1 (پیاپی 50، بهار 1403)

Microgrid is a system of generating and distributing electrical energy. Microgrids include various power systems, each of which has different power capacity and produces different oscillations. By producing reliable and flexible power, microgrids can ensure the safety and electrical reliability of the network and reduce energy costs. A microgrid is a small power system with distributed energy sources and loads, which can work in two modes connected to the grid and island. The controller in a microgrid must provide a seamless transition between different modes of operation. By reviewing the studies, the application of microgrids has expanded to respond to the growing energy demand and solve environmental pollution problems. In this paper, a brief overview of the effectiveness of direct current microgrids in the power system has been provided. Direct current microgrids do not need frequency synchronization and reactive power management, and in terms of stability, flexibility, and complexity, they are superior to alternating current microgrids. The source voltages are the variables that control the direct current microgrid power, so they must be well managed to achieve the desired voltage regulation. Various classifications have been stated for microgrids based on control methods, structures, performance, and other parameters. This review can be considered as an initial platform for research study in the development of direct current microgrids based on centralized and intelligent control.

The aim of this research is to optimize the combined system consisting of solar photovoltaic panels and a diesel generator as two independent decision variables and five responses or the optimization objective function, including system electricity consumption, system gas consumption, diesel fuel consumption, the amount of bio-pollutants reduction. The environment and the return on investment are dependent variables of this research; an optimization method is used to achieve the best possible design in Transis software, and the response level method is used to find the best combination of selected factors in the system. The main purpose of the response surface is to estimate and predict the effect of independent variables on the dependent variable after implementing the system in Transis software and optimizing by the response surface method. The results showed that the area of photovoltaic panels in the optimal state is equal to 11770 square meters and the optimal diesel generator power is equal to 984 kW. Also, in optimal conditions, the system has the best performance, and the combined utility is equal to 0.740, which indicates that the performance of the optimal system is close to the ideal state, i.e., one. In terms of energy consumption, the optimal system achieves a total electricity consumption of 1026860 kilowatts, a total gas consumption of 205182 cubic meters, a total diesel fuel consumption of 1338030 liters, an amount of environmental pollutants of 3693.23 kilograms, and an investment return period of 1.679 years. Also, strategy one, which includes the direct purchase of the total electricity demand from the grid and the direct sale of the total electricity produced by the system to the grid, seems to be economically more economical. The results of the simulation showed that the investigated combined system is a suitable solution to simultaneous energy production. It is electric and thermal, and it is capable of producing electric and thermal energy throughout the year.

Nowadays, with an increasing demand for electrical energy and the high penetration of renewable energy sources, frequency fluctuations pose a significant challenge to power system operators. In this paper, the frequency-load control problem based on the measures of (i) peak overshoot of frequency deviation and (ii) integral of time-weighted absolute error is explored from a new perspective for an interconnected, two-area power system. To this end, the proposed interconnected two-area power system includes thermal, gas, and hydro power generation sources as well as wind and solar renewable energy sources. Additionally, and from a technical perspective, nonlinear factors including dead-band governor and generation rate constraints are also taken into account for the newly developed interconnected two-area power system. To control the frequency, a fractional-order TID controller is widely employed due to its simple structure and high accuracy, the coefficients of which were optimized by a well-adjusted genetic algorithm. For comparison purposes, the performance of the suggested TID controller is compared with a PID controller in terms of dynamic parameters such as frequency deviation range, settling time, and stability speed. Simulation of the proposed interconnected two-area power system in the MATLAB/SIMULINK environment indicates that under various operating conditions the proposed TID controller exhibits better effectiveness and efficiency compared with the PID controller in terms of improving dynamic parameters.

In this paper, a new three-port DC-DC converter is introduced. The designed converter benefits from a small number of elements, and it has a bidirectional port for the battery. This converter can operate in three different operating modes including renewable source-alone mode, battery-alone mode, and battery-charging mode. A prototype of the proposed converter was built and tested in the laboratory. Its dynamic responses to the changes in the input voltage and output load in all three operation modes verified the accuracy of the designed converter.

Transmission networks are always prone to various short-circuit faults in their lines. Fast and accurate fault location is required to improve system reliability by reducing downtime and restoring service. This issue has become more interesting since the advent of wide area communication and measurement technologies. Dependence on the parameter of the protected line, inaccuracy in resistance faults and time-consuming detection of the fault area, and faulty line are among the main disadvantages of the existing methods. This article presents a new integrated fault location algorithm based on differential-impedance calculated from voltage and current phasors collected from two transmission fault terminals. First, the suspected fault line was identified using the differential of the phase angle of the positive sequence current calculated at the two terminals of each line. Then, the exact location of the fault was obtained using the impedance-differential technique. This technique was tested for different types of faults, various locations of fault and fault resistance. The important output of this article is the rapid detection of the fault area, the faulty line, and fault location using a technique based on differential impedance obtained from synchronous measurements on both sides of the line.

In recent years, the Internet of Things (IoT) has emerged as a significant technology in the industrial and academic sectors, particularly in the context of the fourth-generation industry. Encouraging industries, including oil, gas, and electric power sectors to adopt IoT technology expeditiously is crucial due to its numerous advantages. This article focuses on the oil and gas and electric power industry, which is a vital sector in any country, and emphasizes the need for the accelerated implementation of IoT to unlock its potential benefits. Despite the potential of IoT to achieve important and innovative changes in oil, gas, and electric power industries, surveys indicate a slow adoption trend in Iran. Thus, this research aims to identify and model the drivers that influence the implementation of IoT in Iran's oil, gas, and electric power industry supply chain. The research consists of two stages: the identification of drivers through literature review and assessment using the Delphi method and the presentation of a model of drivers using fuzzy total interpretive structural modeling. The results, comprising 75 drivers categorized into 14 general categories, highlight "government regulations" as the most fundamental driver in Iran's oil, gas, and electric power industry supply chain.

Sound produced by vertical axis wind turbines can reduce their popularity for use in urban and residential areas. In order to reduce the produced sound level the acoustic behavior of hybrid rotor is studied in this research with the help of Computational Fluid Dynamics (CFD). In the investigated rotor structure, conventional-type blades were used as the inner rotor, which was connected to the outer rotor at a zero-degree angle. To ensure the modeling, the validation of the results and the measuring of effect of the time step on the output data were undertaken. The purpose of this research was to investigate the effect of a tip speed ratio and free wind speed on the level of sound produced. The results showed that the sound level produced had a direct relationship with a tip speed ratio and the free wind speed in such a way that the lowest sound pressure level in a tip speed ratio of 1.5 and the free wind speed of 5 m/s was reported by the R4 receiver.  Its value was equal to 7.64 dB. Also, by moving away from the rotor, the produced sound level decreasesd.

The sun is a renewable resource that helps reduce carbon dioxide emissions and reduces the impact of industries on nature pollution. In the present study, the effects of using the vortex generator in different geometrical states in the absorber tube of the parabolic solar collector were investigated using the numerical method and with the help of the finite volume method. Vortex generators were modeled with four geometric states, Case A, Case B, Case C, and Case D, and their effect on different parameters in the output of parabolic solar collector was investigated. According to the results, using the vortex generator increased the heat transfer coefficient and the thermal efficiency of the parabolic solar collector. The maximum increase in thermal performance increased by 65.03% compared to when the parabolic solar czollector was a simple.