In current study, a method for achieving a load-independent output current with the ability to optimize the parameter tuning, which is applied to wireless power transfer (WPT) systems, is analyzed. The proposed technique is based on the... more
In current study, a method for achieving a load-independent output current with the ability to optimize the parameter tuning, which is applied to wireless power transfer (WPT) systems, is analyzed. The proposed technique is based on the immittance property in a passive resonant network (PRN) with the purpose of transforming a voltage/current resource into a current/voltage resource. This study determines an immittance conditions-qualified family of PRN, which is associated with a more appropriate topological description in WPT applications. Considering the resource and sink type, a comprehensive specification of the coupling coefficient-based design condition and operating point is carried out. Moreover, the parameters of each proposed topology are reconfigured by adjusting the proportion of active power to reactive power ratios as an index to optimize the topology size as well as a reduction of voltage/current stresses on their elements without changing the specified system-level p...
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In a three-phase distribution system, due to unequal distribution of single-phase loads, load diversities, the different consumption patterns, and growing penetration of renewable energy resources in smart grids, the problem of unbalanced... more
In a three-phase distribution system, due to unequal distribution of single-phase loads, load diversities, the different consumption patterns, and growing penetration of renewable energy resources in smart grids, the problem of unbalanced power flow becomes more challenging. In this paper, we propose a new innovative phase imbalance mitigation (PIM) scheme performed by smart meters. With aid of the proposed optimal phase assignment for 3-phase power distribution input feeders known as phase rearrangement (PR), Electrical storages (ES), and the Renewable energy sources (RES), smart meter owners are inspired to assist the distribution system operator (DSO) in diminishing the phase imbalance. This is achieved by employing a proposed connection point assignment system which has the flexibility of selecting the power input among the three phases and management of ESs and RESs. We model this problem into a mixed integer linear program, where smart meter owners minimize their electricity b...
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Nowadays using from wind power plants in power syst em has increased so that in some countries thermal generation stations exchanged with wind power plants. SCIG generator is popular to use in power plants. B ecause it is cheap and does... more
Nowadays using from wind power plants in power syst em has increased so that in some countries thermal generation stations exchanged with wind power plants. SCIG generator is popular to use in power plants. B ecause it is cheap and does not need to extra maintain. Of course cause of working it in fix speed of wind, there is some limitation to use in it. Therefore in location by fspeed of wind, using from SCIG is economic. At this work, a SCIG simulated in MATLAB Simulink and then exercised different value for its rotor resistance and by tak ing its output power and electromagnetic torque, its results compared and its efficiency inv estigated .
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Reconfiguration in power systems leads to entry of distributed generation. According to specifications, operating conditions and placement, DG units play an important role in distribution networks. High costs of network development and... more
Reconfiguration in power systems leads to entry of distributed generation. According to specifications, operating conditions and placement, DG units play an important role in distribution networks. High costs of network development and consequently energy loss and also the quality requirement of distribution network such as voltage sag, unbalance, etc. using DG resources to be considered. Small generation units located close to or in the load centers. One of the most important tasks for electric companies is to supply safe and appropriate electricity to the costumers. In this paper, the prioritization of seven urban areas has been done to install distributed generation using AHP algorithm. Power quality and load growth are the criterion of prioritization. In this study economic factors for DG placement have not been considered. Results are tested on a real medium voltage grid by Digsilent software to verify the efficiency of distributed generation. The results show that DG permits a...
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The complex structure of the power system and the pivotal role of electrical energy in determining the socio-economic indicators of any countries lead the policy makers of power industry to take into account the expansion planning of... more
The complex structure of the power system and the pivotal role of electrical energy in determining the socio-economic indicators of any countries lead the policy makers of power industry to take into account the expansion planning of generation system with high priority. Considering the intense fluctuations of costs in electrical energy generation (particularly due to variation of fuel prices within the recent years in the Middle East), finding an optimal generation portfolio, regardless of the costs variations risk looks impossible. The portfolio theory, as an efficient tool for risk management, provides a proper solution to materialize the optimal generation portfolios with the following properties: maximizing the expected return for any given level of risk, while minimizing risk for every given level of expected return. Determining an optimal generation technologies portfolio in Iran by the above-mentioned theory is the main aim of this study. To do so, two scenarios have been co...
Long interruptions cause no compensable problems to the power systems and decrease the reliability of the system significantly. One of new technologies that decrease the fault time is Static Transfer Switch (STS) with alternative power... more
Long interruptions cause no compensable problems to the power systems and decrease the reliability of the system significantly. One of new technologies that decrease the fault time is Static Transfer Switch (STS) with alternative power supply. In this study an industrial plant with motor loads has been studied with and without use of STS in front of a voltage fault. The simulations have been done to demonstrate the speed of the motors during the faults. As the interruption duration is an important factor in reliability analyzing, some faults with various durations have been applied to the system to study the reliability of the system with and without STS. The results are given to verify the STS efficiency in increasing the system reliability by restoring the motors' speed drop in least time.
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Abstract This paper presents a fast and adaptive method to locate faults in three-terminal transmission lines, based on the synchronized measurements within the half-cycle data window. First, the voltage and current data are processed by... more
Abstract This paper presents a fast and adaptive method to locate faults in three-terminal transmission lines, based on the synchronized measurements within the half-cycle data window. First, the voltage and current data are processed by two sets of half-cycle Fourier filters at three terminals in order to extract the main component of the voltage and current phasors quickly and with a high accuracy using a novel method. The proposed algorithm uses the calculated phasors and works without any need to transmission line’s data or the Thevenin equivalent of the system at each terminal. For making sure of considering the real operation conditions of the network, transmission line’s parameters are determined adaptively using the calculated phasors. The voltage at the tapping point is calculated separately using three-terminal data and consequently the faulty section is identified and then, the precise location of fault in the faulty section is accurately calculated using the nodal current unbalance method. Performance of the proposed algorithm is evaluated under different fault conditions. The simulation results show the high convergence speed and the excellent accuracy of the proposed method under various operating conditions and various fault types.
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Nowadays, due to technical and economic reasons, the distributed generation (DG) units are widely connected to the low and medium voltage network and created a new structure called micro-grid. Renewable energies (especially wind and... more
Nowadays, due to technical and economic reasons, the distributed generation (DG) units are widely connected to the low and medium voltage network and created a new structure called micro-grid. Renewable energies (especially wind and solar) based DGs are one of the most important generations units among DG units. Because of stochastic behavior of these resources, the optimum and safe management and operation of micro-grids has become one of the research priorities for researchers. So, in this study, the optimal operation of a typical micro-grid is investigated in order to maximize the penetration of renewable energy sources with the lowest operation cost with respect to the limitations for the load supply and the distributed generation resources. The understudy micro-grid consists of diesel generator, battery, wind turbines and photovoltaic panels. The objective function comprises of fuel cost, start-up cost, spinning reserve cost, power purchasing cost from the upstream grid and the...
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This study presents the Chance-Constrained Optimization (CCO) model to solve the problem of Economic Dispatch (ED) and the optimal operation of the energy hub. This problem inherently has a nonlinear nature. To have a tractable model, the... more
This study presents the Chance-Constrained Optimization (CCO) model to solve the problem of Economic Dispatch (ED) and the optimal operation of the energy hub. This problem inherently has a nonlinear nature. To have a tractable model, the proposed model is linearized. Cost minimization is considered as objective function of the problem which is subjected to a suit of constraints. Different flexible elements such as energy storage devices and converters are also considered in the structure of the energy hub. The proposed model is tested on a sample energy hub for one year time horizon. Sensitivity analysis is performed based on the chance-constraint parameters. The results are thoroughly analyzed for the different structures of the energy hub. The results show that considering a well-tuned chance-constraint in the model has a direct impact on the final solution in a cost effective manner.
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Abstract Due to importance of duty cycle based model predictive torque control (MPTC), it has been accepted as an effective and common alternative control strategy for industry. Since its major drawback is great dependency on duty ratio... more
Abstract Due to importance of duty cycle based model predictive torque control (MPTC), it has been accepted as an effective and common alternative control strategy for industry. Since its major drawback is great dependency on duty ratio parameter, the robustness and the complexity of control system has been respectively decreased and increased. A duty-ratio set considering limited members can be replaced with continuous and dependent parameters form duty cycle relationship. Hence, this paper proposes a new and applicable discrete duty cycle control strategy to reduce both the torque and flux ripples appeared in MPTC method. In the proposed method, after preselecting around half of all admissible voltage vectors based on the torque sign or speed variation and the stator flux position, two duty ratios have just been selected for the preselected active voltage vectors. These two duty ratios are achieved based on the equivalent voltage concept with independent motor parameter. Then, the model predictive control method is employed to select the optimum active voltage vector and its relevant duty ratio among the reduced feasible voltage vectors which reduces both the flux and torque ripples, especially in low speed ranges. The simulation results have confirmed the performance of the proposed method in order to reduce the torque and flux ripples, and the experimental results have accordingly validated its performance. Since the number of voltage vectors and duty ratios is significantly decreased, the execution time of the proposed method is further reduced, and virtually worked with a constant switching frequency for all speed ranges.
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A framework has been presented in this paper to plan wind unit and distribution static compensator (DSTATCOM) with an energy storage system (ESS) in the distribution system. This framework is based...
In profit-based unit commitment, the objective of programming is to maximize profit and optimize generation. Practically, the gross profit depends not only on the revenue but also on the total expenditures. In this article, an efficient... more
In profit-based unit commitment, the objective of programming is to maximize profit and optimize generation. Practically, the gross profit depends not only on the revenue but also on the total expenditures. In this article, an efficient algorithm is suggested to assess the effect of uncertainties in determining 24-hour optimal strategy of a microgrid (MG) containing wind farms, photovoltaic, fuel cell, combined heat and power units, boiler, and energy storage devices (ESDs). The optimization problem is presented to determine the optimal points for the energy resources generation and to maximize the expected profit considering demand response (DR) programs and uncertainties. The uncertainties include wind speed, photovoltaic power generation (PVPG), market price, power, and thermal load demand. For modeling uncertainties, an effort has been made to predict uncertainties through the hybrid method of wavelet transform (WT)-artificial neural network (ANN)-imperialist competitive algorithm (ICA). In this study, three cases are assessed to confirm the performance of the proposed method. In the first case study, programing MG is isolated from the grid. In the second case study, which is grid-connected mode the WT-ANN-ICA and WT-ANN uncertainties predictions methods are compered. In the third case, which is grid-connected mode the effect of DR programs on the expected profit of energy resources is assessed.
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We propose a novel stochastic consensus-based secondary voltage and frequency restoration scheme with communication delays and noises for islanded microgrids (<inline-formula><tex-math notation="LaTeX">$\\mu... more
We propose a novel stochastic consensus-based secondary voltage and frequency restoration scheme with communication delays and noises for islanded microgrids (<inline-formula><tex-math notation="LaTeX">$\\mu $</tex-math></inline-formula>Gs). Existing distributed methods commonly design restoration layer with the assumption of ideal communication among distributed generations (DGs). Albeit, the communication channels are exposed to delay and noise, whereas any DG receives delayed and noisy measurements from its neighbors due to peripheral noises and communication delays. Delay and noise have a great impact on the control of <inline-formula><tex-math notation="LaTeX">$\\mu $</tex-math></inline-formula>G, which terribly reduce the stability and quality of it. To eliminate the adverse effects of delays and noises, we propose a novel consensus protocols that consider effects of the communication noises and delays simultaneously for complete plant dynamics, and study mean square consensus for frequency and voltage restoration of <inline-formula><tex-math notation="LaTeX">$\\mu $</tex-math></inline-formula>Gs, whereas providing stringent real power sharing. To this end, we derive the mean square consensus restoration proof using rigorous Lyapunov analysis. As a result the suggested method decreases the sensitivity of the system to failures and increases its reliability. Finally, we have done several simulation scenarios in MATLAB/SimPowerSystems Toolbox to verify the proposed strategy performance.
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Wide area power oscillation damping (WAPOD) is a very effective controller to damp out the inter-area electromechanical oscillations in the wide area power systems. This controller requires communication networks to receive the remote... more
Wide area power oscillation damping (WAPOD) is a very effective controller to damp out the inter-area electromechanical oscillations in the wide area power systems. This controller requires communication networks to receive the remote outputs. The use of communication networks causes delays in feedback loops. This delay reduces the controller's performance. Therefore, in order to improve the performance of the control system in the presence of delay, in this paper a WAPOD controller is designed using delay scheduling for the TCSC supplemental control. To select control structure, a method is proposed that allows optimization of stability in the range of delay. To design the controller, the the real part of the rightmost electromechanical mode is minimized. Case studies is based on a four-machine power system. Effectiveness of the proposed WAPOD controller is verified by simulation studies and compared with a conventional delayed design approach.
The continuing efforts to reduce the torque and flux ripples using Finite Set Model Predictive Direct Torque Control methods (FSMPDTC) have been currently drawing great attention from the academic communities and industrial applications... more
The continuing efforts to reduce the torque and flux ripples using Finite Set Model Predictive Direct Torque Control methods (FSMPDTC) have been currently drawing great attention from the academic communities and industrial applications in the field of electrical drives. The major problem of high torque and flux ripples refers to the consideration of just one active voltage vector at the whole control period. Implementation of two or more voltage vectors at each sampling time has recently been adopted as one of the practical techniques to reduce both the torque and flux ripples. Apart from the calculating challenge of the effort control, the parameter dependency and complexity of the duty ratio relationships lead to reduced system robustness. Those are two notable drawbacks of these methods. In this paper, a finite set of the voltage vectors with a finite set of duty cycles are employed to implement the FS-MPDTC of the induction motor. Based on the so-called Discrete Duty Cycle-base...
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In this paper a new idea of direct three-phase to single-phase Z-source matrix converter (impedance-source matrix converter) applicable in stand-alone wind turbine is introduced. In the direct Z-source matrix converter amplitude of output... more
In this paper a new idea of direct three-phase to single-phase Z-source matrix converter (impedance-source matrix converter) applicable in stand-alone wind turbine is introduced. In the direct Z-source matrix converter amplitude of output voltage and frequency regulation are of importance to control system. In wind turbines, input voltage and frequency are usually changing due to wind speed variation that these alterations could be easily regulated by means of a direct Z-source matrix converter. A scheme is also offered to control the proposed direct three-phase to single-phase Z-source matrix converter. the control strategy would be able to adjust the output voltage and frequency at desired value as well as producing low THD (total harmonic distortion) at the output voltage. The proposed structure and the control methodology are simulated using matlab simulink software and results are investigated and discussed to confirm the performance of the direct Z-source matrix converter in w...
The continuous spread of distributed energy resources (DERs) such as combined heating and power (CHP), diesel generators, boilers and renewable energy sources provide an effective solution to energy related problems to serve the power and... more
The continuous spread of distributed energy resources (DERs) such as combined heating and power (CHP), diesel generators, boilers and renewable energy sources provide an effective solution to energy related problems to serve the power and heat demands with minimum cost. Moreover, the DERs may play a significant role for supplying power and heat in rural areas, where grid electricity is not available. Also, some dry areas may face water scarcity and salinity problems. So, one important solution is the use of DERs to drive desalination units in order to solve water scarcity and salinity problems. In this study, the optimal scheduling of DERs and reverse osmosis (RO) desalination unit that feed the required electric, thermal and potable water demands are determined. The present paper describes the operation constraints and cost function of components of the system in detail. Operation constraints of generation units as well as feasible region of operation CHP in dual dependency charact...
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Inertia response is the first reaction of the generator to the frequency disturbance in power system that is so important for the grid. Conventional synchronous generators have a high inertia response inherently and therefore the power... more
Inertia response is the first reaction of the generator to the frequency disturbance in power system that is so important for the grid. Conventional synchronous generators have a high inertia response inherently and therefore the power system by these generators has a high Inertia response. Recently, using the wind turbines by DFIG generators are become popular,consequently, investigation the Inertia response of DFIG is important. At this work the inertia response of a DFIG that is connected to an infinite bus investigated and it is observed that DFIG has a very low inertia response, because its controller takes the slip of machine within fix range.In this paper for studying on effect of the operation speed of the DFIG controller on its inertia response, several different times took for its controller speed.
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As opposed to the existing approaches which recognize communication network time delays, when they are introduced into the feedback signals, as a main cause of instability or poor performance in power system wide-area damping controller... more
As opposed to the existing approaches which recognize communication network time delays, when they are introduced into the feedback signals, as a main cause of instability or poor performance in power system wide-area damping controller (WADC), this paper shows that if time delay in feedback loops is properly determined, the WADC performance to damp out inter-area oscillations will be improved. In other words, in situations where it is not easy to design and implement the WADC for Flexible AC Transmission Systems (FACTS) devices without delay, in order to effectively compensate the delay, in this paper, a new Wide-Area Damping Controller Delay Effect (WADCDE) is designed. First the model of power system with delay as a design parameter is established. Then, the WADCDE based on objective function of the rightmost real part of eigenvalues is designed and the sufficient condition about stability of the closed-loop system is given. A four-machine power system for numerical simulations h...
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This paper proposes an advanced distribution automation planning problem in which emergency-based demand response plans are incorporated during service restoration process. The fitness function of this planning problem consists of various... more
This paper proposes an advanced distribution automation planning problem in which emergency-based demand response plans are incorporated during service restoration process. The fitness function of this planning problem consists of various costs associated with fault occurrence in electric distribution systems consisting of the total yearly cost of customers’ interruptions, the total annualized investment cost of control and protection devices deployment, including sectionalizing switches, circuit breakers, and fuses and the total annual cost of performing emergency-based demand response programs in service restoration process. Moreover, the customers’ behavior in participating in the service restoration process is also modeled through using an S-function. The proposed advanced distribution automation planning method is implemented on the fourth bus of the Roy Bilinton test system in order to evaluate its efficacy. The obtained results show that the reliability indices and the total ...
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With increasing the number of large-scale photovoltaic (PV) farms (LPFs) connected to the power grids in the world, some characteristics of power systems are affected. Studies show that the LPFs could have the negative effect on... more
With increasing the number of large-scale photovoltaic (PV) farms (LPFs) connected to the power grids in the world, some characteristics of power systems are affected. Studies show that the LPFs could have the negative effect on low-frequency oscillation (LFO) relative to their location and size. Considering that the LPFs cannot be located in ideal points and their installation location depends on geographical conditions, it is important to consider an auxiliary controller as a damping controller for them. On the other hand, the new generation of LPFs has a centralized plant controller (CPC) for voltage and power regulation at the point of common coupling (PCC); therefore, it is required to add the damping controller to the CPC. In this paper, the LFO damping by an optimal damping controller (ODC) that implemented in the CPC of LPFs is proposed. The ODC structure is a single input 2nd-order lead-lag controller. A benchmark test system for LFO studies is used to show the performance ...
The quickest solution towards having a smart grid especially with a strong telecommunication infrastructure is to integrate the conventional electricity meters with IoT services. In this paper, proposing a novel IoT based smart measuring... more
The quickest solution towards having a smart grid especially with a strong telecommunication infrastructure is to integrate the conventional electricity meters with IoT services. In this paper, proposing a novel IoT based smart measuring and control systems a non-cooperative game model is developed to implement a sort of load balancing commands as a DR program activity. Depending on the level of the grid imbalanced current, all three phase customers can participate in and take actions from the smart re-phasing program which has been developed into the proposed algorithm. Telecommunications and sharing information between smart meters are essential to the algorithm because of its distributed structure which makes it computationally tractable. The proposed approach provides a new paradigm for modeling and sets different prices which are computed based on the neutral current value to all grids’ nodes. Re-phasing operations can be done where smart meters are installed and hence any cust...
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This paper proposes a non-cascade -single loop- Direct Speed Control algorithm for surface mounted Permanent Magnet Synchronous Motor (PMSM) fed by Matrix Converter. The proposed method uses Finite Control Set Model Predictive Control... more
This paper proposes a non-cascade -single loop- Direct Speed Control algorithm for surface mounted Permanent Magnet Synchronous Motor (PMSM) fed by Matrix Converter. The proposed method uses Finite Control Set Model Predictive Control (FCS-MPC) to manipulate system speed and currents simultaneously. Also, for better performance of the predictive method, an observer designed to estimate mechanical torque and other uncertain parameters of the mechanical subsystem as a lumped disturbance. Simulation results using Matlab/Simulink demonstrate the performance of proposed algorithm.
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ABSTRACT