فصلنامه مهندسی و مدیریت انرژی
سال دوازدهم شماره 2 (پیاپی 44، تابستان 1401)

In this paper, the operation scheduling of Microgrids (MGs), including Distributed Energy Resources (DERs) and Energy Storage Systems (ESSs), is proposed using a Deep Reinforcement Learning (DRL) based approach. Due to the dynamic characteristic of the problem, it firstly is formulated as a Markov Decision Process (MDP). Next, Deep Deterministic Policy Gradient (DDPG) algorithm is presented to minimize total operational costs by learning the optimal strategy for operation scheduling of MG systems. This model-free algorithm deploys an actor-critic architecture which can not only model the continuous state and action spaces properly but also overcome the curse of dimensionality. In order to evaluate the efficiency of the proposed algorithm, the results were compared with the analytical method and a Q-based learning algorithm which demonstrates the capability of the DDPG method from the aspects of convergence, running time, and total costs.

In this paper, a new method for fault detection, location, and classification in multi-terminal DC microgrid (MTDC) is proposed. MTDC grids have expanded due to some issues such as the expansion of DC resources, loads, and aims to increase power quality. Diagnosing the types and location of faults is important to continue the service and prevent further outages. In this method, a circuit kit is connected to the grid. In fault time, the fault in the network is detected by passing the current through the connected kits and measuring the traveling waves derived from the fault current as well as applying it to a mathematical morphological filter. Determining the location of the fault is done using circuit equations and current calculations. Phaselet output and fuzzy inference systems are used to determine the type of faults. The presented method was tested in an MTDC microgrid connected to renewable and energy storages with many faults. The results show the ability of the proposed method. The error of the proposed fault location method is less than 7%. This method is resistant towards the change in sampling frequency (between 500 Hz and 50 kHz), fault resistance (up to 125 ohms), and loading (up to 120% of the nominal load); it acts very well in high impedance faults.

The Microgrid is a small-scale controlled power system, which can be used in islanded mode or in a grid-connected one to provide power. In the islanded Microgrid, the system frequency will be affected severely by the smallest disturbance which can happen due to light inertia in the system. In the independent Microgrid, several generation sources such as solar, wind, and so on can be considered. In addition to these power plants, the discussion of energy conversion as a result of temperature changes can be considered as a thermoelectric converter. In the present article, the effort has been made to propose a microgrid model which incorporates a Thermoelectric Generator (TEG) system. In this system, due to the variety of uncertainties and load variations, an advanced controller must be developed to improve the dynamic stability and reliability of the microgrid system. The Improved Fuzzy Fractional-Order PID is the suggested controller. The proposed controller is applied to a sample islanded microgrid to establish a robust evaluation and to be checked under parametric changes, great demands, and disturbances. The offered controller is compared with those of other PID, FOPID and FPID controllers. The results of simulations reveal that the proposed controller has a proper and robust performance.

An increase in global temperature, the vital need to reduce environmental emissions resulted from greenhouse gases, and the nonrenewablity of those energy resources have led to a change in attitudes and a turn to deploy advanced technologies and renewable energy resources as an alternative in electric power generation equipment. However, renewable energy resources are not reliable. In fact, the non-reliable nature of these resources has caused the deployment of diesel generators as a backup resource to cover loads in emergency situations. Among these non-reliable resources, biofuels as a substitute for fossil fuels in diesel generators not only stop the emissions of pure CO2 and other toxic pollutants in the air but also save money in the future. In this study, it has been tried to preserve technical specifications and the reliability of system by adding a hydroelectric power plant in addition to wind and solar systems. Furthermore, the use of biodiesel (biofuel) as an alternative in diesel generators can help identify an optimized autonomous hybrid system in terms of minimum costs while considering social costs and emission limits by Homer software of. Vanaei village in Lorestan province, Iran, is presented as acase study.

Bus voltage stability is very important factor in power system reliability.Voltage instability and protection system malfunction can lead to voltage collapse. If power systems cannot meet reactive power demands on a bus, voltage starts to drop. Thus, reactive power compensation can reduce the risk of voltage collapse. In this paper, two new indices are introduced for weak bus identification; also, a method is proposed for reducing the collapse probability of placing capacitors. To this end, the networks of 30 IEEE standard buses were studied; buses were ranked according to the weakest bus identification indices. Network probabilities of being in normal, under-voltage, and risk-and-collapse zones were calculated. By the strategic placement of capacitors with PSO (Particle swarm optimization), the algorithm probability of networks in the collapse zone reduced significantly; also, the performance of proposed indices over other methods was illustrated.

One of the common methods of removing iron oxide from the surface of hot rolled steel sheets is to wash the sheet with acid. The most common acid used in steel industry for this purpose is hydrochloric acid. One of the methods of recycling hydrochloric acid from acid leaching effluent used in steel industry is acid recycling method using fluidized bed reactor. To this end, the effect of this method on the reduction of g environmental challenges, an optimal use of energy, and an increase in efficiency and productivity in steel industry was investigated. In this research, the solvent extraction method as well as evaporation and crystallization method for acid recycling was proposed. The results showed that the solvent extraction method has low efficiency, requires strict system control as well as continuous monitoring; however, the evaporation and crystallization method with the least man power, energy consumption environmental pollution as well as with high efficiency has an acceptable preference. In the evaporation and crystallization method, 17.5% hydrochloric acid solution and iron chloride are recycled; such event has many uses and can be sold. The water from the evaporation and crystallization process can also be used as a product in the factory or used to irrigate the green space in the factory.

One of the main problems in using solar panels is dust which reduces their efficiency. In the present paper, the effect of dust and the angle of installation of the photovoltaic panel on its performance loss in the city of Ilam have been investigated. The experiments were performed using two similar panels in the spring by considering different amounts of dust from 0 to 236.94 g/m2. Voltage, current, and power losses were calculated and the effects of dust and panel angle on them were investigated in a multi-factor experiment based on a completely randomized design. The effect of dust on voltage, current, and power loss was significant at 1% probability level, and their losses increased with an increase in the amount of dust. The lowest performance loss was related to voltage which varied between 1.53% at an angle of 4.8° and the amount of dust at 236.94 g/m2 and 7.84 % at an angle of 26.1° and the amount of dust at 72.28 g/m2. The output current has a greater loss than the voltage, and its highest value (87.19%) was observed in the panel at the angle of 26.1° and the amount of dust at 236.94 g/m2and its lowest value (24.8%) at the angle of 26.1°and the amount of dust at 42.85 g/m2. The highest power loss (87.5%) was related to the angle of 26.1°and the amount of dust at 236.94 g/m2, and the lowest loss (26.5%) was related to the angle of 26.1° and the amount of dust at 42.85 g/m2. It was found that the angle determined based on the geographical location (26.1°) has a lower performance loss than the other angles and, therefore, is a more suitable angle for generating electrical energy in the event of dust.

In the present study, the performance of a parabolic trough solar collector using a hybrid nanofluid and its comparison with a mono nanofluid and a base fluid were theoretically investigated based on a thermal model. Therminol VP-1 was selected as the base fluid and Fe3O4 and Nanocomposite Multi-walled carbon nanotubes- Fe3O4 were selected as the nanoparticles. The fluid flow inside the absorber tube of the collector is assumed to be turbulent. The rsults showed that the energy and exergy efficiencies using hybrid and mono nanofluids were higher than the base fluid. However, their amount using of hybrid nanofluid was slightly less than that of mono nanofluid. The highest enhancement in energy efficiency for hybrid and mono nanofluids compared with the base fluid was equal to 2.17% and 2.22% respectively. Also, the highest enhancement in exergy efficiency was 1.49% and 1.58% respectively. On the other hand, the friction factor of mono nanofluid in average was about 7% higher than that of hybrid nanofluid. The results showed that the thermal-hydrodynamic efficiency (performance evaluation criterion) of the collector (performance evaluation criterion) using hybrid nanofluid was higher than that of mono nanofluid.

In this study, the simultaneous effects of fuel injection timing and the use of syngas on the production of pollutants and the performance of a compression ignition engine with controlled reactivity have been investigated. Numerical solution of changing fuel injection timing from 10 to 30 degree before Top Dead Center and fuel compounds in three normal diesel modes, diesels with two ratios of 20 and 40% syngas (including hydrogen and carbon monoxide) are examined in this study while maintaining energy constant for each cycle. The results show that as the ratio of Syngas increases, the pressure and heat release rate into the cylinder increase; it is while, these values with the postponement of fuel injection timing​​have decreased. In addition, nitrogen oxide production is increased by the addition of syngas such as carbon monoxide, while delays in fuel injection timing reduce nitrogen and carbon dioxide oxides and increase carbon monoxide. The contamination of particulate matter has been greatly reduced by the addition of syngas, which continues to decrease with the delay in fuel injection timing. Also, the use of syngas, by delaying the timing of fuel injection, reduces the indicated power and indicated thermal efficiency while it increases the indicated fuel consumption. Finally, a 40% ratio of syngas and fuel injection timing of 10 degree before Top Dead Center is a good strategy to reduce pollutants.

After years from the first day of operating a power plant, it has been seen that the pipes of the high-temperature super heater suffer from damage and failure. In-depth investigations have revealed that the damage has occurred suddenly and remained heavy ruining instrumentations and buildings. Experiments and finite-element numerical simulations are conducted to understand the risk factors. The experiments such as gas flue analysis, hardness test for both intact and damaged tubes, the morphology of the failure part, and the analysis of the sediment inside the tubs are done. The main reasons for the failure of the super heater unit are found to be: striking hot flue gases with temperature of 530° Celsius and the stress of thermal elongation of the tubes .With the obtained results, some remedies such as using soot removal systems, using high-quality fuels, modifying combustion systems for applying fuels out of design, and using adjustable burners can be presented to solve the aforementioned problems. The current results can be valuable for other researchers to prohibit similar phenomena.