فهرست مطالب

  • Volume:15 Issue: 1, 2019
  • تاریخ انتشار: 1397/12/12
  • تعداد عناوین: 13
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  • R. Mohammadi , H. Rajabi Mashhadi * Pages 1-13
    Distribution system reliability programs are usually based on improvement of average reliability indices. They have weakness in terms of distinguishing between reliability of different customers that may prefer different level of reliability. This paper proposes a new framework based on game theory to accommodate customers’ reliability requests in distribution system reliability provision. To do this, distribution reliability equations are developed so that it is recognized how game theory is suitable for this purpose and why conventional methods could not provide customer reliability requirements appropriately. It would be shown that customer participation in distribution system reliability provision can make conflict of interest and leads to a competition between customers. So, in this paper a game theoretic approach is designed to model possible strategic behavior of customers in distribution system reliability provision. The results show that by implementing the proposed model, distribution utilities would have the capability to respond to customers’ reliability requirements, such that it is beneficial for both utility and customers.
    Keywords: Distribution System, Game Theory, Reliability, Smart Grid
  • S. Hajiaghasi*, K. Abbaszadeh , A. Salemnia* Pages 14-28
    Interturn fault detection is a challenging issue in power transformer protection. In this paper, interturn faults of distribution transformer are studied and a new online detection method based on vibration analysis is proposed. Transformer electromagnetic forces are analyzed by time stepping finite element (TSFE) modeling of interturn fault. Since the vibration associated with inter-turn faults is caused by electromagnetic forces, axial and radial electromagnetic forces for various interturn faults are studied. Transformer winding vibration under interturn faults is studied through an equivalent mathematical model combined with electromagnetic force analysis. The results show that it is feasible to predict the interturn winding faults of transformer windings with the transformer vibration analysis method. Simulation and experimentation studies are carried out on 20/0.4 kV, 50 kVA distribution transformer. The results confirm the effectiveness of the proposed method.
    Keywords: Transformer, Vibration, Interturn Fault, Electromagnetic Force.
  • E. Babaei*, M. Shadnam Zarbil , E. Shokati Asl Pages 29-44
    In this paper, a new topology for cascaded multilevel inverter based on quasi-Z-source converter is proposed. In the proposed topology the magnitude of output DC voltage is not limited to the sum of magnitude of DC voltage sources. Moreover, the reliability of the circuit due to capability of short circuit by Z-source network is increased. The quasi-Z- source converter in different modes is analyzed and the voltage gain is obtained. Also, the values of quasi-Z-source network components are designed. In the proposed topology, the number of DC voltage sources, the number of switches, installation area and cost in comparison with conventional multilevel inverters are significantly reduced. Three algorithms to determine the magnitude of DC voltage sources are proposed. Then the optimal structures for the minimum number of switches and DC voltage sources to generate the maximum voltage levels are presented. Moreover, the control method for the proposed topology is described. To verify the performance of the proposed topology, simulation and experimental results of proposed topology are presented.
    Keywords: Z-Source Converter, Quasi-Z-Source Converter, Multilevel Inverter, Shoot-Through, Optimization
  • H. Benbouhenni*, Z. Boudjema , A. Belaidi Pages 45-55
    This article presents an improved direct vector command (DVC) based on intelligent space vector modulation (SVM) for a doubly fed induction generator (DFIG) integrated in a wind turbine system (WTS). The major disadvantages that is usually associated with DVC scheme is the power ripples and harmonic current. To overcome this disadvantages an advanced SVM technique based on fuzzy regulator (FSVM) is proposed. The proposed regulator is shown to be able to reduce the active and reactive powers ripples and to improve the performances of the DVC method. Simulation results are shown by using Matlab/Simulink.
    Keywords: DVC, DFIG, SVM, FSVM, Fuzzy Regulator, Powers Ripples.
  • V. Abbasi*, S. Hemmati , M. Moradi Pages 56-64
    Stress grading (SG) layer in cable terminations limits the critical electric field and properties of SG materials are important issues which have to be considered during manufacturing and selecting procedure. In this paper, two different types of (SG) materials are analyzed by both theory and test. According to the applied theory, important parameters as: electrical resistivity, breakdown voltage and thermal conductivity are determined by experiments. Experimental steps are defined in the paper with which theory and experiments are matched together to complete the investigation. The paper discusses electro-thermal breakdown theory and quality of two different SG layers based on the test results. The theory and experimental procedure can be used for prediction of breakdown voltage in cable terminations. The employed method is useful for qualifying the cable terminations by users who want to buy and install heat shrink cable terminations.
    Keywords: Cable Termination, Stress Grading Tube, Critical Electric Field, Nonlinear Material, Insulation Layers
  • M. Aghamohamadi , M. Samadi*, M. Pirnahad Pages 65-75
    The integration of different energy types and new technological advances in multi-energy infrastructures, enable energy hubs (EH) to supply load demands at a lower cost which may affect the price responsive loads, since the energy could be offered with a lower price at the EH output ports, compared to the upstream energy markets. In this paper a new EH operation model is proposed by which the optimal responsive load modifications against the obtained EH output energy prices as well as the EH schedules are determined. To achieve this goal, a tri-step approach is proposed. At the first step the EH output energy prices are obtained for each energy type in each hour of the scheduling horizon. These energy prices are based on the EH hourly operation and would change as the EH operation changes. At the second step, the optimal responsive load modifications against the obtained EH output energy prices are simulated using the new proposed integrated responsive load model which is capable to model the price responsive loads in multi-energy systems for any type of energy carrier. Since, any changes in load demand (due to its responsiveness) can jeopardize the EH power balance constraint, the obtained EH operation would be infeasible, considering the new modified load pattern. To cope with this interdependency, a new iterative methodology is proposed at the third step in which, the EH optimal operation + EH output energy price determination + responsive load modification is implemented in a loop till the 24 hour aggregated load modification becomes lower than the pre-determined convergence tolerance. Based on the obtained results from solving the proposed methodology through a comprehensive case study, the aggregated supplied energy has been increased by 7.3%, while, the customers payments has reduced by 14.6%. Accordingly, the customer’s satisfaction has increased.
    Keywords: Demand Response, Energy Price, Energy Conversion, Storage, Energy Hub, Energy Internet
  • P. Asgharian , R. Noroozian * Pages 76-86
    Microturbine generation system is one of the most promising and a fast growing distributed generation sources. It is used in various applications thanks to high efficiency, quick start and high reliability. Combination of the microturbine and storage system (e.g. battery bank) is desirable selection to satisfy the load requirements under all conditions and hence the battery bank can play an important role in restoring balance between source and demand. In this paper, modeling of the microturbine with battery energy storage system is presented to supply sensitive loads. Appropriate power exchange between battery and the microturbine is an essential issue so, a new control method is proposed for battery energy storage based on instantaneous value of DC-link voltage. In this new strategy, DC-link voltage as well as battery parameters (current and voltage) are used in order to produce desirable DC-DC switching. A control scheme based on voltage, current and frequency measurement is presented for the corresponding inverter. Simulations are carried out in MATLAB/Simulink software and the results show that storage along with proper control improves system reliability to supply sensitive load. The proposed configuration can be used as a remote power, emergency power and also in micro-grid.
    Keywords: Microturbine Generation System, Battery Energy Storage, New Control Strategy, Isolated Mode, Sensitive Load
  • R. Shariatinasab*, M. Rasuli , J. Gholinezhad Pages 87-93
    In this paper a novel method based on evolutionary algorithms is presented to estimate the harmonic components. In general, the optimization of the harmonic estimation process is a multi-component problem, in which evaluation of the phase and harmonic frequency is the nonlinear part of the problem and is solved based on the mathematical and evolutionary methods; while estimation of amplitude of the harmonic component is a linear issue that is performed by combining the least squares method with the aforementioned approaches. In this paper, firstly, the optimal estimation of integer harmonic components has been introduced based on the improved shuffled frog leaping algorithm (ISFLA) in the presence of two types of noise. The obtained results present the lower error of the proposed method than to IGHS, FBF PSO, GA and FFT methods. Thereafter, the effectiveness of the presented algorithm in optimal estimation of frequency, phase, and amplitude of the integer and non-integer harmonics are investigated. The optimization of the estimation of various harmonic components under different conditions using ISFLA leads to an improvement in the assessment of power quality in power systems especially in the distribution networks, considering a lot of the nonlinear loads and harmonic resources connected to the network.
    Keywords: Harmonic Estimation, Sub-Harmonics, ISFLA, Power Quality.
  • O. Herbadji , L. Slimani , T. Bouktir * Pages 94-113
    In this study, a multiobjective optimization is applied to Optimal Power Flow Problem (OPF). To effectively achieve this goal, a Multiobjective Ant Lion algorithm (MOALO) is proposed to find the Pareto optimal front for the multiobjective OPF. The aim of this work is to reach good solutions of Active and Reactive OPF problem by optimizing 4-conflicting objective functions simultaneously. Here are generation cost, environmental pollution emission, active power losses, and voltage deviation. The performance of the proposed MOALO algorithm has been tested on various electrical power systems with different sizes such as IEEE 30-bus, IEEE 57-bus, IEEE 118-bus, IEEE 300-bus systems and on practical Algerian DZ114-bus system. The results of the tests proved the versatility of the algorithm when applied to large systems. The effectiveness of the proposed method has been confirmed by comparing the results obtained with those obtained by other algorithms given in the literature for the same test systems.
    Keywords: Optimal Power Flow, Multiobjective Ant Lion Algorithm, Algerian Electrical Network, Generation Cost, Environmental Pollution Emission, Active Power Losses, Voltage Deviation
  • S. G. M. Rokni , M. Radmehr*, A. Zakariazadeh Pages 114-125
    In this paper, a new energy management method is proposed for residential consumers based on a distributed algorithm. Consumers could participate in demand response programs by managing their schedulable and deferrable loads as well as using of photovoltaic (PV) systems. In the proposed method, the Alternating Direction Method of Multiplier (ADMM) is used to model the distributed management and scheduling of buildings electricity consumption. By implementing the distributed algorithm, a large number of residential consumers can update their consumption parameters by online communication with the central controller in parallel. The results confirm that residential customers are able to reduce their electricity bill by modifying their electricity consumption patterns without reducing their welfare.
    Keywords: Demand Response, Residential Consumers, Distributed Algorithm, Electricity Bill.
  • A. Younesi , H. Shayeghi * Pages 126-141
    The purpose of this paper is to design a supplementary controller for traditional PID controller in order to damp the frequency oscillations in a micro-grid. Q-learning, which is used for supervise a classical PID controller in this paper, is a model free and a simple solution method of reinforcement learning (RL). RL is one of the branches of the machine learning, which is the main solution method of Markov decision process (MDPs). The proposed control mechanism is consisting of two main parts. The first part is a classical PID controller which is fixed tuned using Salp swarm algorithm. The second part is a Q‑learning based control strategy which is consistent and updates its characteristics according to the changes in the system continuously. Eventually, a hybrid micro-grid is considered to evaluate the performance of the suggested control method compared to classical PID and fractional order fuzzy PID (FOFPID) controllers. The considered hybrid system is consisting of renewable energy resources such as solar-thermal power station (STPS) and wind turbine generation (WTG), along with several energy storage devices such as batteries, flywheel and ultra-capacitor with physical constraints and time delays. Simulations are carried out in various realistic scenarios considering system parameter variations along with changing in operating conditions. Results indicate that the proposed control strategy has an excellent dynamic response compared to the traditional PID and FOFPID controllers for damping the frequency oscillations in different operating conditions.
    Keywords: Mini, Micro-Grid, Q-Learning, Adaptive Controller, Frequency Oscillation Enhancement.
  • M. H. Lazreg*, A. Bentaallah Pages 142-150

    This article presents a sensorless five level DTC control based on neural networks using Extended Kalman Filter (EKF) applied to Double Star Induction Machine (DSIM). The application of the DTC control brings a very interesting solution to the problems of robustness and dynamics. However, this control has some drawbacks such as the uncontrolled of the switching frequency and the strong ripple torque. To improve the performance of the system to be controlled, robust techniques have been applied, namely artificial neural networks. In order to reduce the number of sensors used, and thus the cost of installation, Extended Kalman filter is used to estimate the rotor speed. By viewing the simulation results using the MATLAB language for the control. The results of simulations obtained showed a very satisfactory behaviour of the machine
    Keywords: Double Star Induction Machine, Direct Torque Control (DTC), Five Level Inverter, Artificial Neural Network
  • M. Khodsuz*, S. Seyyedbarzegar Pages 151-160
    The essential role of surge arresters is equipment protection against over-voltages to increase system reliability. Different monitoring techniques have been used to diagnose surge arrester condition. Leakage current analysis methods by the extraction resistive and capacitive components of leakage current are a conventional method for surge arrester monitoring. Insufficient appropriate thresholds are most important restriction of these kinds of methods. In this paper, the impact of pollution, ultraviolet aging and varistors fault on harmonic spectrum of leakage current have been evaluated experimentally. Real tests and examinations have been done on different metal oxide surge arresters to investigate effects of mentioned factors on leakage current harmonics. To show results performance, bees-adaptive network based fuzzy inference system has been applied.
    Keywords: Surge Arrester, Harmonics Analysis, Leakage Current, Diagnostic, Bees-ANFIS