Power
Ali Morsagh Dezfuli; Mahyar Abasi; Mohammad Esmaeil Hasanzadeh; Mahmood Joorabian
Abstract
The utilization of distributed generation (DG) in today's power systems has led to the emergence of the concept of microgrids, in addition to changing the mode of generating and supplying the energy required for network electrical loads. When a microgrid operates in the island mode, energy generation ...
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The utilization of distributed generation (DG) in today's power systems has led to the emergence of the concept of microgrids, in addition to changing the mode of generating and supplying the energy required for network electrical loads. When a microgrid operates in the island mode, energy generation sources are responsible for controlling the microgrid’s voltage and frequency. As the microgrid frequency is proportional to the amount of power generated by the DG, the microgrid requires a precise power-sharing strategy. Considering that DGs do not usually have stable output power despite the importance of power stability, the present paper addresses the voltage and frequency control of an islanded microgrid by considering the power generation uncertainties caused by disturbances and the varying power output of DGs. Given that the disturbance on the first DG's input current is 0.2 A, which is approximately 2.2% of the steady-state value, a simulation was performed, and it was observed that the maximum voltage variation of each bus in the worst case was 0.59% for the first bus and 0.53% for the second bus, which means that the controller could control the voltage and frequency values within the permissible range. If the controller is not used, the change in the frequency of each bus will be 10 times, and the voltage change will be 5 times as great as that of the case the controller is used.
Power
Zahra Gholami; Rahim Ildarabadi; Hamed Heydari-doostabad
Abstract
This paper discusses the application of the principle of duality to conventional voltage-based DC-DC converters, such as buck, boost, fly-back, cuk, sepic, and zeta topologies, in order to obtain their current-based DC-DC converters. The duality approach involves finding the dual of a circuit, which ...
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This paper discusses the application of the principle of duality to conventional voltage-based DC-DC converters, such as buck, boost, fly-back, cuk, sepic, and zeta topologies, in order to obtain their current-based DC-DC converters. The duality approach involves finding the dual of a circuit, which is a circuit equivalent to the original circuit but with certain parameters swapped. Therefore, this paper presents a comprehensive study on achieving the most commonly used topologies of DC-DC current converters by applying the duality approach to their DC-DC voltage converters. This approach serves as a solution for applications where a current source is available and there is a need for output current control. An application of these current converters is to power current-based loads, such as light-emitting diodes (LEDs), and to provide conversion for current sources, such as photovoltaics (PV). As an advantage, these converters do not require additional inductors at their input or output terminals. Additionally, the paper provides a detailed explanation of the principle of operation and mathematical analysis of the conversion ratio for the discussed current converters. The proposed current converters and their application as an interface between a PV and a high-power LED were simulated using MATLAB to verify the mathematical equations. Overall, this paper provides a useful study guideline for understanding the principle of duality and the application of DC-DC current converters for current-based loads and sources.
Power
Sajed Derakhshani Pour; Reza Eslami
Abstract
In the last few years, there has been growing attention to isolated DC microgrids (MGs) with robust voltage control and efficient responding to demand in the face of fluctuating demands and supply amounts. This attention is due to significant voltage mismatches originated ...
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In the last few years, there has been growing attention to isolated DC microgrids (MGs) with robust voltage control and efficient responding to demand in the face of fluctuating demands and supply amounts. This attention is due to significant voltage mismatches originated from the sudden transitions of the load demand and the active power of the supplies such as photovoltaic (PV) systems. To address these goals, a novel nonlinear robust voltage control strategy with a cascaded design consisting of proportional-integral (PI) and sliding mode control (SMC) techniques is developed in this research for the battery energy storage system (BESS). Additionally, this research considers a fuel cell as another power supply in addition to a solar PV system. For maximum power point tracking (MPPT) of the PV system, a novel backstepping sliding mode control (BSMC) technique is developed as well. The effective functioning of the suggested cascaded control strategy is examined using MATLAB/Simulink. The outcomes of the simulation represent the effectiveness of the proposed approach in robustly regulating the voltage level of the DC link at 50 V with small deviations in tracking, and quick reaction to fluctuations in both demand and supply sides, as well as guaranteeing an evenly-distributed responding to demand fluctuations from the DC MG.
Power
Ramin Arjmandzadeh; Mahdi Banejad; Ali Akbarzadeh Kalat
Abstract
In conventional power systems, most of the power is produced by synchronous generators in the electric grid that have heavy and rotating rotors. As a result, there is an inherent inertia in the rotor of these generators. The presence of inertia in the grid prevents sudden frequency changes during imbalance ...
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In conventional power systems, most of the power is produced by synchronous generators in the electric grid that have heavy and rotating rotors. As a result, there is an inherent inertia in the rotor of these generators. The presence of inertia in the grid prevents sudden frequency changes during imbalance situations, thus, the frequency stability of the grid is maintained. Today, with the increase of renewable energy sources that are usually connected to the network by power electronic equipment. Such resources do not have rotating materials, therefore, the overall inertia of the grid decreases and the stability of the system deteriorates. To solve the problem of lack of inertia in the power electronic-based grid, the notion of the virtual synchronous generator (VSG) technology has been introduced in recent years. This technology can imitate the behavior of traditional synchronous generators for inverters connected to the grid. In this way, the inverters connected to the grid act like a synchronous generator during imbalance. One of the problems associated with the converters-based microgrid is the existence of DC deviations and additional harmonics, which disrupt the work of the converters. Therefore, in this article, a third-order generalized integrator (TOGI) -based VSG for grid-connected inverters is employed so that the system stability is maintained in the conditions of additional harmonics and DC deviation. To show the effectiveness of the proposed method, time domain simulations have been performed in Simulink/MATLAB software. The results of the simulation verify the performance of the proposed method.
Power
Asaad Shemshadi; Mohammad Reza Khojaste
Abstract
One type of electrical breakdown in solid insulation is electromechanical failure. In mineral processing, crushing rocks is energy-intensive. Rock crushing using high voltage has many advantages, including high stone-breaking efficiency, and is a new and efficient way to break the stone. The shape of ...
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One type of electrical breakdown in solid insulation is electromechanical failure. In mineral processing, crushing rocks is energy-intensive. Rock crushing using high voltage has many advantages, including high stone-breaking efficiency, and is a new and efficient way to break the stone. The shape of the electrode, the amount of applied voltage, and the selection of drilling process parameters are the main obstacles to using this method. In this study, based on the equivalent circuit of high voltage electro pulse failure, a mathematical model of high voltage electro pulse discharge in rock has been developed. Then, a high-voltage simulation model is developed based on the coaxial cylindrical electrode structure. This paper investigates the use of electromechanical failure phenomena for crushing minerals. High voltage pulses are used to crush the rock, then by simulating the relevant circuit, the necessary voltage for crushing three minerals is obtained and the feasibility of using this method is discussed. Finally, using the simulation and the obtained results, the possibility of using this method for crushing minerals has been investigated. This study provides a scientific basis for quantifying and predicting rock crushing using high-voltage technology to improve drilling efficiency and reduce energy loss.
Power
Nicholas Kwesi Prah II; Elvis Twumasi; Emmanuel Asuming Frimpong
Abstract
The Combined Economic Emission Dispatch (CEED) is an important consideration in every power system. In this paper, a modified Mayfly Algorithm named Modified Individual Experience Mayfly Algorithm (MIE-MA) is used to solve the CEED optimization problem. The modified algorithm enhances the balance between ...
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The Combined Economic Emission Dispatch (CEED) is an important consideration in every power system. In this paper, a modified Mayfly Algorithm named Modified Individual Experience Mayfly Algorithm (MIE-MA) is used to solve the CEED optimization problem. The modified algorithm enhances the balance between exploration and exploitation by utilizing a chaotic decreasing gravity coefficient. Additionally, instead of the MA relying solely on the best position, it calculates the experience of a mayfly by averaging its positions. The CEED problem is modeled as a nonlinear optimization problem constrained with four equality and inequality constraints and tested on a grid-connected microgrid that consists of four dispatchable distributed generators and two renewable energy sources. The performance of the MIE-MA on the CEED problem is compared to Particle Swarm Optimisation (PSO), an MA variant that incorporates a levy flight algorithm named IMA and Dragonfly Algorithm (DA) using the MATLAB R2021a software. The MIE-MA achieved the best optimum cost of 11306.6 $/MWh, compared to 12278.0 $, 12875.8$, and 17146.4$ of the DA, IMA, and PSO respectively. The MIE-MA also achieved the best average optimum cost over 20 runs of 12163.48 $, compared to 12555.36 $, 13419.67 $, and 17270.08 $ of the DA, IMA, and PSO respectively. The hourly cost curve of the MIE-MA was also the best compared to the other algorithms. The MIE-MA algorithm thus achieves superior optimal values with fewer iterations.
Power
Elvis Twumasi; Yussif Seini Abdul-Fatawu; Emmanuel Asuming Frimpong
Abstract
The optimal size and location of series capacitors is a critical challenge in a distribution network. In this paper, a novel approach for enhancing voltage stability in distribution networks through the optimal sizing and placement of series capacitors is proposed. The study introduces a technique to ...
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The optimal size and location of series capacitors is a critical challenge in a distribution network. In this paper, a novel approach for enhancing voltage stability in distribution networks through the optimal sizing and placement of series capacitors is proposed. The study introduces a technique to determine the optimal lines for connecting series capacitors based on line reactance and current. A modified Elephant Herding Optimization (MEHO) algorithm was used to determine the reactance sizes of the series capacitors and the best lines to place them for optimum system performance. To evaluate the effectiveness of the proposed method, three series capacitors are placed and sized in the standard IEEE 33-bus radial distribution system for stability enhancement. A comparison is conducted between the proposed MEHO algorithm-based approach, the original Elephant Herding Optimization (EHO) algorithm, and the IGWO-TS-based methods reported in the literature. The evaluation is performed by analyzing the system voltage profile, total system losses, and system voltage deviation index under varying loading conditions of 30%, 100%, and 120% of the system nominal loading. Results demonstrate that the proposed MEHO algorithm-based approach outperforms the other two methods significantly in all the scenarios, highlighting its effectiveness in voltage stability enhancement in distribution networks.
Power
Mohammad Naser Hashemnia
Abstract
Modeling electric machines is crucial for analyzing their behavior and designing controllers. It is of the utmost importance to make use of a consistent equivalent circuit of the Doubly Fed Induction Machine (DFIM) that is applicable to a variety of operating modes. This is because it helps in the calculation ...
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Modeling electric machines is crucial for analyzing their behavior and designing controllers. It is of the utmost importance to make use of a consistent equivalent circuit of the Doubly Fed Induction Machine (DFIM) that is applicable to a variety of operating modes. This is because it helps in the calculation of the machine's steady-state performance, converter ratings, and controller set-points. Traditional models of doubly fed induction machines employ the steady-state equivalent circuit of a wound-rotor induction machine with all rotor parameters referred to the stator through a frequency conversion. The present study investigates the validity of the traditional steady-state circuit model by taking into account the sequence change in rotor voltages and currents at super-synchronous speeds. The validity of phasor diagrams constructed using the traditional circuit is assessed, with a particular focus on super-synchronous operation in both motoring and generating modes. It has been demonstrated that the existing model is applicable to all rotor speeds (whether sub-synchronous or super-synchronous). However, caution should be exercised when utilizing expressions of rotor reactive power that involve dynamic dq and steady-state phasor models. Therefore, modified expressions are developed for rotor reactive power that are applicable regardless of the operating speed. The accuracy of the proposed method for different operating modes is confirmed by comprehensive simulation results developed with Matlab® Simulink. An investigation is also conducted into the sensitivity of rotor reactive power direction to parameter changes, and it is shown that machine parameter changes have a negligible effect on rotor reactive power direction.
Power
Ahmad Ghafari; Mohsen Saniei; Morteza Razzaz; Alireza Saffarian
Abstract
Increasing the penetration level of distributed generation (DG) units in radial power distribution systems can increase the short-circuit level in these networks, which can, in turn, have destructive effects such as exceeding the tolerable current of the equipment and disrupting the protective coordination ...
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Increasing the penetration level of distributed generation (DG) units in radial power distribution systems can increase the short-circuit level in these networks, which can, in turn, have destructive effects such as exceeding the tolerable current of the equipment and disrupting the protective coordination in the network. The active superconducting fault current limiter (ASFCL) is a new device that can limit fault current using voltage series compensation. This paper discusses the modeling of ASFCL and control strategies including fault detection and converter performance in normal and fault modes. Initially, its performance in limiting the fault current is investigated by simulating a sample three-phase system with ASFCL. In the next step, three operating modes including normal mode, upstream fault mode, and downstream fault mode are proposed to achieve an adaptive FCL that solves these problems in grid-connected microgrids. The simulation results confirm the proper performance of the ASFCL modes in both fault current limiting and protective coordination of overcurrent relays in the network.
Power
Nabil Mezhoud; Mohamed Amarouayache
Abstract
This paper presents a solution to the Optimal Power Flow (OPF) problem combined economic dispatch with valve-point effect and Emission Index (EI) in electrical power networks using the physics-inspired optimization method, which is the Gravitational Search Algorithm (GSA). Our main goal is to minimize ...
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This paper presents a solution to the Optimal Power Flow (OPF) problem combined economic dispatch with valve-point effect and Emission Index (EI) in electrical power networks using the physics-inspired optimization method, which is the Gravitational Search Algorithm (GSA). Our main goal is to minimize the objective function necessary for the best balance between energy production and its consumption which is presented in a nonlinear function, taking into account equality and inequality constraints. The objective is to minimize the total cost of active generations, the active power losses, and the emission index. The GSA method has been examined and tested on the standard IEEE 30-bus test system with various objective functions. The simulation results of the used methods have been compared and validated with those reported in the recent literature. The results are promising and show the effectiveness and robustness of the used method. It should be mentioned that from the base case, the cost generation, the active power losses, and the emission index are significantly reduced to 823 ($/h), 6.038 (MW), and 0.227 (ton/h), which are considered 5.85%, 61.61%, and 44.63%, respectively.
Power
Mohammad Afkar; Parham Karimi; Roghayeh Gavagsaz-Ghoachani; Matheepot Phattanasak; Serge Pierfederici
Abstract
In fuel cell systems, voltage balancing is an important consideration. The utilization of a modular construction based on a three-level boost converter was able to balance DC voltage. This paper investigates the effect of parameter variations, such as inductors and capacitors, on the converter's steady-state ...
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In fuel cell systems, voltage balancing is an important consideration. The utilization of a modular construction based on a three-level boost converter was able to balance DC voltage. This paper investigates the effect of parameter variations, such as inductors and capacitors, on the converter's steady-state controllable areas. The plot of the inductor current and the voltages of the output capacitors are illustrated for different scenarios. The system simulation results were performed using MATLAB / Simulink software.
Power
Reza Rostaminia; Mehdi Vakilian; Keyvan Firouzi
Abstract
Partial Discharge (PD) measurement is one of the best solutions for condition assessment of Gas Insulated Switchgears (GISs). For having Condition-based maintenance of GIS, online PD monitoring is of great importance. For this aim, Ultra High Frequency (UHF) PD sensors should be installed inside the ...
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Partial Discharge (PD) measurement is one of the best solutions for condition assessment of Gas Insulated Switchgears (GISs). For having Condition-based maintenance of GIS, online PD monitoring is of great importance. For this aim, Ultra High Frequency (UHF) PD sensors should be installed inside the GIS during the installation. However, in most installed GISs in industries, the internal UHF PD sensors are not installed. In this paper, a new method for online defect type recognition according to external UHF PD sensors and based on the time-frequency representation of PD signal is proposed. In this case, four artificial defect types named protrusion on the main conductor, protrusion on the enclosure, free moving metal particle, and metal particle on spacer are implanted inside the 132 kV L-Shaped structure of one phase in enclosure GIS. The signal energy at each level of the decomposed signal by Discrete Wavelet Transform (DWT) is applied for features of each defect type. The trends of signal energy variations at each frequency range of signal are applied for discriminating between each defect type. The Deep Feed Forward Network (DFFN) classifier is applied for PD pattern recognition. The results show the benefits and simplicity of the proposed method for PD signal classification, independent from the position of the PD sensor, especially in the case of online PD monitoring of GIS.
Power
Saeed Aminzadeh; Mehrdad Tarafdar Hagh; Heresh Seyedi
Abstract
This paper uses the coordination between the reactive power of a solid oxide fuel cell (SOFC) and a battery to control the frequency within an islanded microgrid. By this coordination, the microgrid frequency regulation becomes faster and better during contingencies. Moreover, the energy storage capacity, ...
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This paper uses the coordination between the reactive power of a solid oxide fuel cell (SOFC) and a battery to control the frequency within an islanded microgrid. By this coordination, the microgrid frequency regulation becomes faster and better during contingencies. Moreover, the energy storage capacity, which is usually required for the frequency control of islanded microgrids, has significantly been reduced. Furthermore, there will be no need to consider reserve capacity in renewable sources for frequency control. Therefore, renewable energy sources can be operated at their maximum power point. Also, this paper introduces a new frequency-reactive power control concept and a related coefficient that shows the degree of dependence of the microgrid frequency on the injected reactive power changes at each bus. This coefficient determines the priority of buses for the installation of reactive power control devices to control the frequency of the microgrid. Simulation studies have been performed in the MATLAB/Simulink environment. The results show the applicability and accuracy of the proposed coefficient and demonstrate the effectiveness of the coordinated control of reactive power between the SOFC and the battery for frequency control.
Power
Reza Rostaminia; Mehdi Vakilian; Keyvan Firuzi
Abstract
Partial Discharge (PD) measurement is one of the main methods for condition monitoring of Gas Insulated Switchgears (GIS). Internal Ultra High Frequency (UHF) sensors can be applied for capturing PD propagated electromagnetic signals within the GIS. PD sensor placement inside the GIS is one of the main ...
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Partial Discharge (PD) measurement is one of the main methods for condition monitoring of Gas Insulated Switchgears (GIS). Internal Ultra High Frequency (UHF) sensors can be applied for capturing PD propagated electromagnetic signals within the GIS. PD sensor placement inside the GIS is one of the main challenges for designing the online PD measuring system. For this aim, the impacts of different GIS components on the propagated PD electromagnetic wave should be studied. In this paper, different PD sensor position angles (with respect to PD sensor), are applied for investigating their sensitivity on the measuring PD electromagnetic wave. Two distinguishable parameters from the calculated PD electromagnetic waves, the first rated electric field and the signal’s power over the two frequency ranges (0.3-2 GHz and 0.3-3 GHz) are used for analyzing and quantifying the calculation results. The impacts of different enclosure diameters, different types of spacers, and various disconnector contact gap distances (under different voltage levels) on this wave propagation are studied. Additionally, the two standard GIS busbar profiles, named: L-shape and T-shape; are discussed in this paper. The results of this study show that the attenuation degree of the measured PD EM waves is strongly influenced by the busbar dimensions and its components configurations. The GIS busbar designer can employ these results to select the proper PD sensors and their installation locations.
Power
Ali Rouhipour; Elaheh Mashhour; Mohsen Saniei
Abstract
This paper develops a new model for the optimal placement of switches (both manual and automatic ones) in distribution networks to simultaneously reduce energy loss and improve network security. Expected energy not supplied (EENS) is assumed as the security index, and a method is developed for more exact ...
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This paper develops a new model for the optimal placement of switches (both manual and automatic ones) in distribution networks to simultaneously reduce energy loss and improve network security. Expected energy not supplied (EENS) is assumed as the security index, and a method is developed for more exact calculation of this index regarding drastic climatic changes along with global warming and the resultant effects on both power consumption patterns and power network occurrence. The objective function of the problem is minimizing investment and maintenance costs, the cost of energy loss, and EENS cost. The suggested model can locate optimal places for installing the switches and their seasonal closed and open states so that the total costs can be minimized. The model is implemented on two test networks and evaluated under different scenarios. According to the results, despite the higher costs of automatic switches, the application of automatic switches is more economical in low-security networks for improving network security.
Power
Saeid Hasheminejad
Abstract
This paper presents a novel method to discriminate between the magnetizing inrush and external and internal fault currents in power transformers. Fault type identification and faulted phase selection are also possible by the proposed algorithm. The proposed method has two main parts. First, by means ...
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This paper presents a novel method to discriminate between the magnetizing inrush and external and internal fault currents in power transformers. Fault type identification and faulted phase selection are also possible by the proposed algorithm. The proposed method has two main parts. First, by means of S-transform, which is the most accurate method in the field of signal processing, some useful features are extracted from the input signal. Then, the extracted features are converted to some numerical indices. In the second part, an effective decision maker is needed to classify the input signal. One of the best methods, which have been used for decision-making applications is fuzzy logic. So, the numerical indices are used as inputs for the fuzzy system. The output of the fuzzy system not only can reveal whether the input signal is the magnetizing inrush, external or internal fault, but it can also identify the fault type when there is an internal fault. Finally, the faulted phases can be identified with a supplemental algorithm. To generate the test signals, a three-phase transformer is modeled in PSCAD/EMTDC. Testing the proposed algorithm by different simulated data shows the robustness of the proposed method in the transformer differential protection.
Power
Farhad Amiri; Mohammad Hassan Moradi
Abstract
With the presence of distributed energy resources in the microgrid, the problem of load-frequency control (LFC) becomes one of the most important concerns. With changing the parameters of the microgrid components as well as the disturbances forced to the grid, designing a suitable LFC becomes more difficult. ...
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With the presence of distributed energy resources in the microgrid, the problem of load-frequency control (LFC) becomes one of the most important concerns. With changing the parameters of the microgrid components as well as the disturbances forced to the grid, designing a suitable LFC becomes more difficult. In this paper, the design of a Robust model predictive controller (RMPC) based on the linear matrix inequality as a secondary controller LFC system is discussed for controlling a microgrid on the shipboard. The main purpose of the proposed method is to improve the frequency stability of the microgrid in the presence of disturbances and the uncertainty of its parameters. The proposed controller simulation results, in several different scenarios, considering The uncertainty of the microgrid parameters as well as the input disturbances are compared. The main controllers are the fuzzy proportional-integral type1 and 2, and multi-objective multi-purpose functions optimized with the MOFPI (MBBHA), MOIT2FPI (MBHA) algorithm. The effectiveness of the proposed method in terms of The response speed and reduction of fluctuations and overcome uncertainties of the parameters, as well as robustness to disturbances, are discussed. Simulation is implemented in MATLAB software. The proposed method reduces the frequency oscillations caused by disturbances on the microgrid by 68% (68% improvement over other methods used in this field). Also, using this method, the damping speed of microgrid frequency fluctuations is increased by 53% (performance improvement).
Power
Moaiad Mohseni; Mahmood Joorabian; Afshin Lashkarara
Abstract
Internet of Things (IoT)-based energy management systems (EMSs) are considered a new technology in which consumers can manage their electricity payments according to their preferences, such as reducing costs or increasing satisfaction. Each consumer has its own program for communicating with a central ...
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Internet of Things (IoT)-based energy management systems (EMSs) are considered a new technology in which consumers can manage their electricity payments according to their preferences, such as reducing costs or increasing satisfaction. Each consumer has its own program for communicating with a central control unit. In addition, the central control unit that is responsible for energy pricing can access consumer information and network performance status through the IoT infrastructure. Therefore, technical analysis can be performed using big data to determine the optimal price in order to make a compromise between the buyer and the goals of the distribution system operators. This paper presents a model to accurately assess the impact of pricing on the behavior of IoT-based energy systems. Then, according to the load specifications of each item and the technical limitations of the distribution network, the best time to use pricing is determined. The results show that the higher the price variance, the more discomfort the consumer and the lower the daily payment. Therefore, in this paper, the main goal of energy management is to minimize the total weight of the costs paid and their discomfort level. The paper could facilitate further penetration of IoT-based EMSs into smart grids. The study was performed on an IEEE standard 33-bus network. Optimization was implemented using YALMIP and MOSEK toolboxes. Therefore, it can be concluded that IoT technology allows consumers to enjoy the benefits of the network and makes optimal consumption management possible.
Power
Hamid Radmanesh
Abstract
This paper presents a new algorithm for sizing equations of an Axial Flux Permanent Magnet (AFPM) machine based on an analytical method. To obtain a better performance, the dimensions of the stator and rotor cores are calculated. It is shown that the magnetic flux densities throughout these cores remain ...
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This paper presents a new algorithm for sizing equations of an Axial Flux Permanent Magnet (AFPM) machine based on an analytical method. To obtain a better performance, the dimensions of the stator and rotor cores are calculated. It is shown that the magnetic flux densities throughout these cores remain closed to the flux density of the B-H curve knee point of the ferromagnetic material characteristics. A new algorithm is proposed to determine the dimensions of the different parts of the machine, and it is used to calculate the height of the permanent magnet precisely. To show the effectiveness of the suggested algorithm, a sample AFPM machine is designed based on sizing equations, and Finite Element Analysis (FEA) is employed to validate these design formulas. A complete simulation study is accomplished, and some of the results are presented to confirm the accuracy of the sizing equations.
Power
Mahyar Abasi; Nima Heydarzadeh; Arash Rohani
Abstract
The phenomenon of broken conductor faults (BCFs) in power transmission lines and, consequently, the suspension of the hot-line with no connection to ground, tower, or other conductive/non-conductive bodies is amongst special faults in terms of fault detection and location in the protection industry. ...
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The phenomenon of broken conductor faults (BCFs) in power transmission lines and, consequently, the suspension of the hot-line with no connection to ground, tower, or other conductive/non-conductive bodies is amongst special faults in terms of fault detection and location in the protection industry. Once such a failure occurs, the current of the faulty phase does not increase, which leads to the inability of standard fault detection functions in detecting the event. On the other hand, the variable nature of transmission line parameters due to weather conditions leads to misoperation and malfunction of fault detection and protection schemes of industrial relays in some cases. This paper, for the first time, presents a BCF location scheme without requiring line parameters data and only using magnitudes of current and voltage phasors of a single terminal based on Group Method of Data Handling (GMDH). In this method, a function is interpolated, the inputs of which are the current and voltage of the faulty phase, and its output are the accurate location of the fault. The function can be developed for all topologies of transmission lines. The proposed method is implemented in the MATLAB software and the obtained results verify the solidity and perfect performance of the method for different fault conditions.
Power
Mahyar Tofighi-Milani; Sajjad Fattaheian-Dehkordi; Mahmud Fotuhi-Firuzabad
Abstract
Microgrids, which have newly been included in power systems, have facilitated the management of distributed generations. In this context, the privatization of power systems, as well as flexible sources like electrical vehicles and storage systems, has been enhanced significantly by the advent of microgrids. ...
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Microgrids, which have newly been included in power systems, have facilitated the management of distributed generations. In this context, the privatization of power systems, as well as flexible sources like electrical vehicles and storage systems, has been enhanced significantly by the advent of microgrids. In a microgrid structure, the microgrid’s operator coordinates the agents and ensures the reliability of the network, while the agents manage their local resources independently. Nonetheless, new management methods should be implemented into the multi-agent-structured microgrids to meet their distributed nature. This paper proposes a new peer-to-peer energy market to optimize the operation of a multi-agent microgrid run in the isolated mode. The designed framework facilitates power trading between the system agents and addresses the privacy issues of the network consumers or producers. The proposed scheme is finally simulated on a 15-bus multi-agent-structured microgrid to study its effect on microgrid management in the isolated mode.
Power
Behzad Jaafari; Alireza Namadmalan
Abstract
This paper presents a design procedure and a new control method for power regulation of series resonant Induction Heating (IH) systems using a self-oscillating tuning loop. The proposed power regulator can accurately estimate the instantaneous phase angle and the main parameters of the resonant load. ...
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This paper presents a design procedure and a new control method for power regulation of series resonant Induction Heating (IH) systems using a self-oscillating tuning loop. The proposed power regulator can accurately estimate the instantaneous phase angle and the main parameters of the resonant load. Moreover, the power control algorithm is devised based on a combination of Phase Shift (PS) and Pulse Density Modulation (PDM) methods. For simplicity, the tuning loop utilizes the PS control method for power regulation. Moreover, the Pulse Density Modulation (PDM) and frequency-sweep methods can be used in the proposed tuning loop. The new method is verified by a laboratory prototype with an output power of about 220 W and an operating frequency of about 60 kHz.
Power
Saman Ghahghahzadeh; Mohammad Reza Afsharnia
Abstract
This work proposes a new model for dynamic behavior of hydro-electric turbines on the basis of inlet mechanical power with different loads together with reactions of wicket gates and governor during load rejection. Then, practical experiments are investigated, and their results are compared with simulated ...
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This work proposes a new model for dynamic behavior of hydro-electric turbines on the basis of inlet mechanical power with different loads together with reactions of wicket gates and governor during load rejection. Then, practical experiments are investigated, and their results are compared with simulated results developed in SIMULINK. The results show that proposed modeling satisfies practical behavior of real systems.
Power
Shabnam Rezaei; Ahmad Ghasemi
Abstract
This paper proposes a novel day-ahead energy hub scheduling framework aimed at improving resiliency. Accordingly, an energy hub including combined heat and power (CHP), boiler, electric-heat pump (EHP), absorption and electric chillers, energy storages and renewable sources is considered. This energy ...
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This paper proposes a novel day-ahead energy hub scheduling framework aimed at improving resiliency. Accordingly, an energy hub including combined heat and power (CHP), boiler, electric-heat pump (EHP), absorption and electric chillers, energy storages and renewable sources is considered. This energy hub is equipped with smart grid (SG) infrastructures, making it possible to implement demand response (DR) programs and optimally operate energy storages. The hub is connected to the electricity and natural gas networks. Outage of input energy carriers causes failure of devices in the energy hub, loss of electrical loads, failure in cooling and heating and thus reduced resiliency. Maintaining the security of the hub consumers’ power supply system in the event of such severe disturbances is essential. Therefore, a new strategy based on the use of backup electric energy storages (EES) and DR program is proposed in this paper to improve resiliency. In addition, a numerical index is used to accurately calculate and evaluate resiliency. Numerical studies show that the proposed strategy improves resiliency during the outage of power and gas networks by 12.02% and 14.23% respectively when backup energy storages and DR program are implemented simultaneously.