Journal of Applied Research in Electrical Engineering
https://jaree.scu.ac.ir/
Journal of Applied Research in Electrical Engineeringendaily1Tue, 05 Mar 2024 00:00:00 +0330Tue, 05 Mar 2024 00:00:00 +0330Improving the Performance of a VSG in the Distorted Grid Using Third-Order Generalized Integrator
https://jaree.scu.ac.ir/article_18757.html
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.Voltage and Frequency Control Considering Disturbance in Input Power of DG
https://jaree.scu.ac.ir/article_18861.html
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&rsquo;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.Solving Combined Economic Emission Dispatch Problem Using the Rain Optimization Algorithm
https://jaree.scu.ac.ir/article_19094.html
An obstacle in managing economic dispatch is the integration of diverse factors such as pollution and heat. By introducing the price penalty coefficient, this class of two-objective problems is transformable to a single-objective form. The formulation considers various practical constraints of the system, including non-smooth cost functions, the balance of production, demand, and losses, and the limitation of power generation by active generators. One of the fundamental difficulties in tackling these types of complex problems lies in the algorithms and solvers employed to identify optimal solutions for a range of operation problems. The rain optimization algorithm (ROA) has been utilized in this paper. ROA is derived from the inherent tendency of raindrops to seek out the lowest areas on the earth's surface. This algorithm possesses exceptional efficacy in resolving problems characterized by stringent constraints and is adept at circumventing local optima. To validate the proposed method for cost and emission reduction, the scheme under consideration has been developed using software on standard systems. The implementation of the scenarios has revealed that the limits of the power system have led to a decrease in the overall generation cost of fossil fuel generation units. In this article, the ROA algorithm managed to plan the production with an optimal cost of 38481.54 dollars in case 1, which obtained a more optimal value than all the compared algorithms. This reduction in cost is considered one of the triumphs of the optimization problems. The results showcased and juxtaposed in the software simulation verify the effective performance of the suggested approach in comparison to prior research.Conventional DC-DC Converters Through Duality Approach for Current-Based Applications
https://jaree.scu.ac.ir/article_18987.html
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.Efficient Responding to Demand and Robust Voltage Control of an Islanded DC Microgrid Under Variations in Load and Supply
https://jaree.scu.ac.ir/article_19035.html
In the last few&nbsp;years, there has been&nbsp;growing&nbsp;attention&nbsp;to isolated DC microgrids (MGs) with robust voltage control&nbsp;and efficient&nbsp;responding to demand in the face of fluctuating demands&nbsp;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.Demand Response Design for Healthy Operation of Transformers in Heavy-Load and High-Temperature Conditions
https://jaree.scu.ac.ir/article_19080.html
The healthy operation of high-power transformers plays a crucial role in the reliability of power systems. Given the thermal model of transformers under heavy-load and high-temperature conditions, the hot spot temperature exceeding the maximum allowable value may result in oil dissolution and cascading. This paper uses a thermal model of transformers to analyze the hot spot temperature load level under predicted ambient temperature, which may cross the healthy conditions. Then, an Incentive-Based Demand Response (IBDR) and a thermal model of transformers are used to determine optimal load curtailment. On the other hand, as the paper uses the demand response (DR) for security reasons, the risk of load participation in IBDR programs should be minimized. Hence, a Response Fatigue Index (RFI) is employed to maintain the comfort level of demands participated in DR. Also, the feasible solution area for multi-objective optimization is determined, given costs and RFI, using the sequential solution of a single-objective problem with cost reduction as the objective and RFI as the constraint with different levels of maximum acceptable RFI. The developed model was applied to a real substation in Iran as a test case. The results show that DR can enhance the reliability and life expectancy of the transformer while keeping the comfort level of loads as high as possible.Analysis of the Potential of Different Air Conditioner Brands for Piezoelectric Energy Harvesting
https://jaree.scu.ac.ir/article_19120.html
Piezoelectric energy harvesting from air conditioner compressors is a promising technology for generating renewable electricity. This study comprehensively compares the energy harvesting potential derived from mechanical vibrations in compressors across various air conditioner brands, harnessing piezoelectric systems. Initially, a data collection system rooted in Internet of Things (IoT) technology is employed to capture vibration signals from different branded air conditioner compressors. The acquired data undergoes pre-processing and is subsequently analyzed in MATLAB Simulink to gauge its energy harvesting potential through a piezoelectric framework. Notably, the maximum voltage harvested demonstrated strong positive correlations with both the compressor vibrational frequency (0.7892) and velocity (0.7855), emphasizing their role in determining available mechanical energy for conversion to electrical power. Furthermore, a moderate positive correlation (0.0659) was observed between the harvested voltage and the compressor's rated power, indicating its influence on energy conversion. An additional positive correlation (0.2839) between temperature and harvested voltage was attributed to the increased electrical conductivity of compressor materials at higher temperatures. Conclusively, the compressor's frequency and velocity emerged as primary determinants of the maximum voltage harnessed, with rated power having a less pronounced yet contributory effect. This research provides valuable insights for optimizing energy harvesting from air conditioner compressors, highlighting the pivotal role of operational parameters.Assessing Power System Adequacy and Generation Expansion Planning in the Presence of Wind Power Plants Considering Uncertainties in the DIgSILENT Software Environment
https://jaree.scu.ac.ir/article_19209.html
Renewable energy sources are particularly important in clean energy transitions and must be considered in Generation Expansion Planning (GEP) problems due to low cost, ease of installation, and ability to implement Demand Response (DR) programs. However, challenges such as the stochastic nature of renewable energy sources, consumer unawareness regarding participation in DR programs, and difficulties in integrating some resources have posed challenges to the use of these resources in the GEP problem. This paper addresses these challenges by using the Weibull distribution function to model wind power plants' uncertainty and rewards and penalties to motivate consumer participation in the GEP problem. To achieve these objectives, initially, the adequacy assessment of the generation system is performed analytically using the reliability index, which includes Expected Energy Not Supplied (EENS), considering the forced outage rate of generators in the DIgSILENT power factory through Python programming. Subsequently, an optimized GEP model is presented to enhance the generation system's adequacy against short-term demand for the next year. In this model, wind farms along with the DR program are integrated and optimized using the genetic algorithm, employing Python programming. The genetic algorithm selects the number of existing turbines in the wind power plant and the level of consumer participation needed to reduce the EENS to the desired value at the minimum cost. Validation of the proposed model is conducted on a 9-bus network. The strength of the presented method lies in its applicability to real-world networks modeled in the DIgSILENT power factory.Reliability Evaluation of Power Systems Including Pumped-Storage Generation Units
https://jaree.scu.ac.ir/article_19210.html
In recent years, energy storage systems are increasingly used in power systems to store electricity when the generated power is more than the required load. The advantages of the energy storage systems in the power system include improved reliability, energy storage in non-peak times and production in peak times that results in the peak reduction of the power system, storage at times of low electricity prices, and generate at times of high electricity prices, and storage of the surplus production capacity of renewable energy resources such as wind turbines and photovoltaic systems that their production is not controllable. Among different energy storage systems, pumped-storage generation units can be integrated into electricity networks with high-energy storage capacity and no environmental effects. For this purpose, in this research, the adequacy assessment of power systems including pumped-storage generation units is studied. At first, the paper develops a reliability model for these energy storage systems considering the failure of composed components including the motor-generator, pump-turbine, control, protection and measurement systems, turbine housing, water channel, up and down reservoir and transformer. To consider effect of pumped-storage generation plants on the reliability of the power system, the load duration curve of system is modified. Then, the proposed model is implemented for assessing the adequacy of power systems considering the effect of generation and transmission networks using an analytical method through contingency analysis technique. To study the effectiveness of suggested reliability model, numerical results related to reliability assessment of RBTS and IEEE-RTS are presented. It is concluded from numerical outcomes that pumped storage power plants can improve the reliability indices of the power systems. Integration of understudied pumped storage generation unit into RBTS, system load can increase up to 15 MW.Wide Area Robust Controller Design for SSSC to Improve the Oscillations Caused by the Time Delay of Remote Signals
https://jaree.scu.ac.ir/article_19211.html
The penetration of double-fed induction generators (DFIG) as renewable energy sources (RES) in power systems leads to fluctuations caused by wind energy. Therefore, based on this challenge, a wide area damping controller (WADC) has been designed to compensate the oscillatory modes by a static synchronous series compensator (SSSC). In addition to the design of WADC for SSSC, a parallel compensator in the form of a supercapacitor energy storage system (SCESS) has been used in the DC link of the wind unit so that DFIG can be used optimally to supply the power system. The design method for compensating time delays in WADC is based on free weight matrices (FWM). First, based on the theory of robust control based on delay-dependent feedback, a set of constraints related to linear matrix inequality (LMI) are formulated. In the following, the free weight matrix (FWM) has been used to solve the delay-dependent time problem. The purpose of applying FWM is to extract the most optimal gain for the controller in the presence of time delay. The proposed FWM matrix tries to find the most optimal gain in the controller with the help of an iterative algorithm based on the linearization of conical complement. The simulation results have been implemented in the MATLAB software environment after obtaining the critical modes in the nonlinear time domain on the power system of 16 improved machines. Based on the simulation results, the robustness of the proposed controller under various uncertainties is clearly shown in this paper.Network Virtualization Utilizing Blockchain: A Review
https://jaree.scu.ac.ir/article_19212.html
Network Virtualization (NV) techniques enable high scalability and isolation by abstracting physical resources to provide a logical network representation that can coexist with a physical networking framework. Traditional NV is prone to security attacks and has lower privacy and trustfulness compared to blockchain-established NV. We diagnose the BC-established NV construct under 5 segments and closely appraise the literature in reference to NV technique, virtualization technology, BC-related properties, and network properties. We racked up a starting sample of 85 sources by filtering literary work for qualifying conditions searched from article retrieval platforms, engaging a rigorous and prolonged approach. Anchored from this research, in BC-established NV, we demonstrate that BC can act as a broker/manager for NV, act as a secure storage by preventing double-spending attacks, provide secure virtual network embedding with high fault tolerance, engage BC and smart contacts for resource trading in the process of NV, engage dedicated consensus approaches to reach agreement for NV among multiple parties for reducing security attacks, and establish BC-established access control for NV. Complete interpretation disseminates that from interpreted BC-established NV schemes, 45% engage BC and smart contracts for agreements and resource trading for NV, 95% engage regular BC architecture, Proof-of-Work (PoW) and Practical Byzantine Fault Tolerance (PBFT) being the most frequently used consensus, 80% engage the overlay network concept, and it has been engaged abundantly (27.5%) in 5G networks. Finally, we deliberate the possibilities and obstacles of the framework of blockchain-established NV and then provide suggestions to suppress them.A New Topological Method for Output Voltage Clamping of Immittance-based Constant Current Load Resonant Converters
https://jaree.scu.ac.ir/article_19217.html
In this paper a new improved diode-based circuit is introduced for output voltage limiting of immittance-based constant current Load Resonant Converters (LRCs). The proposed Diode-based Voltage-Limiter (DVL) is very reliable and simple, and also has minimum number of components. Moreover, limiting values are flexible and can be varied according to the design requirements. All of the positive characteristics of the LRC operation are preserved in this technique such as Zero Voltage Switching (ZVS) of the inverter switches and Zero Current Switching (ZCS) of the rectifier diodes. A 150W converter with 300kHz switching frequency is considered as a sample prototype. The circuit simulation is presented based on the real model of the semiconductor devices in the OrCAD environments to have maximum accordance with the real conditions. Simulation results demonstrate an accurate clamping ability of the output voltage for overload conditions without any characteristics variation.Voltage Regulation in Low Voltage Distribution Networks Using Reactive Power Capability of Photovoltaic Inverters (PV) and PID Consensus Algorithm
https://jaree.scu.ac.ir/article_19359.html
The dominant measures taken in distribution networks to solve the problem of voltage instability include feeder reconfiguration techniques, allocation of capacitor banks, use of tap changers, etc. However, these traditional methods suffer from numerous problems. Many studies have been carried out to solve these problems in recent years. Compared with traditional methods, reactive power control (RPC) of photovoltaic (PV) inverters does not require additional investment, and given that PV inverters often function at a capacity below their rated value, the excess capacity can be utilized to assist in supplying reactive power to the grid. However, achieving voltage regulation in imbalanced distribution networks via RPC is a complex issue. Hence, the primary objective of this work is to utilize the reactive power capacity of photovoltaic inverters to achieve decentralized regulation of effective voltage of the network using a consensus algorithm and PID controller in two stages.Optimization of PSS and UPFC Controllers to Enhance Stability by Using a Combination of Fuzzy Algorithm and Shuffled Frog Leaping Algorithm
https://jaree.scu.ac.ir/article_19362.html
Maintaining power system stability can be challenging due to low-frequency fluctuations. Traditionally, power system stabilizers (PSS) and unified power flow controllers (UPFC) have been used to address this issue. This paper proposes a novel approach that leverages both PSS and UPFC simultaneously, controlled by an optimized fuzzy logic system. The proposed fuzzy controller aims to enhance the efficiency of both PSS and UPFC, ultimately boosting system damping. The controller takes two key inputs: changes in angular speed and power angle. To dynamically adjust its response to changing system conditions, a shuffled frog leaping algorithm optimizes the fuzzy controller's gains. To assess the effectiveness of the controller, simulations are conducted across three different loading levels for the studied system. The results are presented for each stage and demonstrate a significant reduction in overshoot and improved overall system damping. Our method achieves a remarkable 43% enhancement in damping compared to PSS, a 45% improvement over UPFC alone, and a staggering 48% advantage over the hybrid PSS-UPFC approach.Economic Analysis of Photovoltaic Systems During Peak Load of the Electric Power Distribution System in the Presence of Electric Vehicles
https://jaree.scu.ac.ir/article_19364.html
Considering the challenges of using fossil fuels including price and pollution and the increasing development of electric vehicles, the energy supply from other sources should be considered. One of the main challenges of electric vehicles is their impact on the distribution network, especially the time of charging and its coincidence with the peak load of the network, which causes an increase in power consumption, double pressure on the network, and more and faster depreciation of distribution network equipment. Also, producing more energy during peak times leads to increased costs and air pollution. In this paper, the use of renewable energy to charge electric vehicles is investigated in such a way that the consumers of electric vehicles use solar panels and batteries to store solar energy so that it can be used for charging during peak times. The costs of installing solar panels, the consumption of electric vehicles, the amount of energy generation, as well as the emission of fossil fuel pollutants that fossil power plants produce at peak times have been investigated. Furthermore, a comparison has been made between the use of renewable and non-renewable energy. Consequently, the proposed method is about 112494 dollars more economical than the system without renewable energy. It is also suggested to consider incentives from the government for the consumer to reduce the capital and operating cost of the photovoltaic system to diminish the investment return time.Improving Power Quality Using a Fuzzy Inference System-Based Variable Forgetting Factor Recursive Least Error Square Control Scheme of DSTATCOM
https://jaree.scu.ac.ir/article_19390.html
A two-layer combined control method is developed for a four-leg Distribution Static Synchronous Compensator (DSTATCOM). The method aims at harmonics reduction, demand-generation equilibrium, power factor modification, voltage adjustment, and neutral current modification in a 3ph 4-wire distribution system. In the first layer, a recursive Least Error Square algorithm (RLES) based on a new fuzzy logic-based variable forgetting factor is used for Real-time estimation of voltage and current signals and their constituting components. The second layer&rsquo;s duty is to extract the reference currents using the outputs of the first layer. Besides the high accuracy and convergence speed, the suggested algorithm is independent of coordinate transformations and complex computation when attempting to derive the reference currents of DSTATCOM. To enhance the dynamic performance of DSATATCOM, an adaptive hysteresis band current controller was utilized to generate switching signals. The effectiveness of the presented control strategy was verified via simulation studies implemented in MATLAB/Simulink environment.Comparative Analysis of Lithium-ion Battery for Long and Short Pulse Discharge Experiments in State-of-Charge Estimation with Extended Kalman Filter
https://jaree.scu.ac.ir/article_19418.html
This paper explores the impact of two types of experiments, known as "long pulse" and "short pulse,"&nbsp; experiments, on identifying models for Lithium-ion batteries. The focus is on improving the estimation of the state of charge (SoC) using an extended Kalman filter. The results consistently demonstrate that applying the extended Kalman filter to models identified through long pulse experiments outperforms those identified through short pulse experiments in estimating battery SoC and terminal voltage. The article delves into the reasons for this improvement from both circuit and electrochemical perspectives, providing insights into the obtained results. Thus, the study advocates for the preference of long pulse strategies to enhance the performance of Lithium-ion batteries, offering insights that contribute to the development of innovative and sustainable energy storage solutions.Improvement of IBC-SHJ Solar Cell Efficiency Based on Back Contacts Geometry Engineering
https://jaree.scu.ac.ir/article_19420.html
In this study, the effect of the width of the n- and p-strips and gap between the electrodes on output characteristics of the IBC-SHJ solar cell including short-current current density, open-circuit voltage, fill factor and efficiency was investigated using Silvaco ATHENA and ATLAS simulation software. In this regard, the efficiency of the IBC-SHJ solar cell was improved by developing the geometry of the back contacts. The values for the short-circuit current density, open-circuit voltage, fill factor and efficiency of the solar cell were analysed using physical phenomena and the distribution of the electric field and electric potential for the aforementioned parameters. The results have shown that the width of the n- and p-strips is one of the most effective parameters for improving the efficiency improvement. Moreover, a maximum efficiency of 23.52% was achieved for IBC-SHJ with improved solar cell parameters, focusing on the elimination of additional ARCs and greater structural periodicity. Thus, a simple structure with no complexity in the fabrication process is proposed. The results show that the best width of the p-strip, n-strip and gap between the electrodes is 400 &mu;m, 80 &mu;m and 30 &mu;m, respectively, to achieve improved efficiency.