Journal of Operation and Automation in Power EngineeringJournal of Operation and Automation in Power Engineering
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Feed provided by Journal of Operation and Automation in Power Engineering. Click to visit.Optimal Short-Term Coordination of Desalination, Hydro and Thermal Units
http://joape.uma.ac.ir/article_767_144.html
The fossil fuels consumption is rapidly growing due to increased water and electricity demands. An interconnected water-energy nexus is generally composed of thermal power plants, combined potable water and power (CWP) generation units, and desalination only processes. Hence, participation of hydro power plants in electricity generation facilities not only reduces the total fuel consumption of the thermal generators and CWP units, but also mitigates the greenhouse gas emissions. In addition, CWP producers reduces the fossil fuels consumption of the conventional thermal power plants and desalination only units, especially when the water treatment and the power generation capacities of the desalination only processes and the conventional thermal units are insufficient for satisfying on-peak potable water and electricity demands. Hence, the main objective of the current paper is to schedule the water-power hub networks in the presence of the hydro units. The generalized algebraic mathematical modeling system is used to model the proposed method as the mixed-integer non-linear program. The on/off status of the units, the value of the power generation of the thermal/hydro/CWP units, the volume of the water produced by the CWP/desalination units are selected as the decision variables of the optimization problem. The sum of the fuel cost of mentioned units is minimized as the single objective function. The optimization constraints consist of the ramp up and down rates of thermal units, water and electricity generation capacities, balance constraints, relationship between the water head, spilled and released water of the reservoirs with output power of hydro power plants.Mon, 30 Sep 2019 20:30:00 +0100Multi-objective Grasshopper Optimization Algorithm based Reconfiguration of Distribution Networks
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Network reconfiguration is a nonlinear optimization procedure which calculates a radial structure to optimize the power losses and improve the network reliability index while meeting practical constraints. In this paper, a multi-objective framework is proposed for optimal network reconfiguration with the objective functions of minimization of power losses and improvement of reliability index. The optimization problem is solved by multi-objective grasshopper optimization algorithm (MOGOA) which is one of the most modern heuristic optimization tools. To solve an optimization problem, the suggested algorithm mathematically mimics and formulates the behavior of grasshopper swarms. The modifying comfort zone coefficient needs grasshoppers to balance exploration and exploitation, which helps the MOGOA to find an exact approximation of global optimization and not trapped in local optima. The efficiency of the suggested technique is approved regarding the 33-bus and 69-bus test systems. Optimization results expressed that the suggested technique not only presents the intensified exploration ability but also has a better solution compared with previous algorithms.Mon, 30 Sep 2019 20:30:00 +0100Resilient Operation Scheduling of Microgrid Using Stochastic Programming Considering Demand ...
http://joape.uma.ac.ir/article_769_144.html
Resilient operation of microgrid is an important concept in modern power system. Its goal is to anticipate and limit the risks, and provide appropriate and continuous services under changing conditions. There are many factors that cause the operation mode of micogrid changes between island and grid-connected modes. On the other hand, nowadays, electric vehicles (EVs) are desirable energy storage systems (ESSs) because of clean transportation. Besides, energy storage systems are helpful to decrease power generation fluctuations arising from renewable energy sources (RESs) in new power systems. In addition, both sides (EV and RESs’ owners) can gain a good profit by integrating EVs and RESs. Therefore, in this paper, a resilient operation model for microgrid is presented considering disasters and islands from the grid. In the proposed formulation, microgrid (MG) operator schedules its energy resources, EVs and ESSs in minimum cost considering demand response (DR) program and resiliency of the microgrid to islanding and uncertainties in market price, load, and generation of RESs. The impact of uncertainties is modeled in the scenario based framework as stochastic programming. The efficiency of presented method is validated on IEEE standard test system and discussed in two cases.Mon, 30 Sep 2019 20:30:00 +0100Potentiometric of the Renewable Hybrid System for Electrification of Gorgor Station
http://joape.uma.ac.ir/article_775_0.html
In this paper, an optimal design of the renewable combustion plant has been investigated with the aim of ensuring the required load on the Gorgor station. The purpose of this study is to minimize the cost of the proposed hybrid unit during the period of operation of the designed system simultaneously. Information on the intensity of solar radiation and the intensity of wind blowing in the area are taken and applied in the simulation of the system. The intended target function includes the cost of investment, replacement cost and maintenance cost. After the design phase, the main objective is to check the economic benefits of the project's utilization from the grid and compare it with the renewable electricity system, as well as to calculate the initial investment return in renewable electricity. First, the initial cost of consuming electricity from this project is calculated using a renewable electricity system, and then the cost of project is determined using the national grid. Further, by calculating the annual current cost of each of these combinations, the investment return in each mode is obtained. Various options for the use of renewable energies are surveyed separately and in combination. The technical-economic analysis is done on each of these options and ultimately the best one is presented.Fri, 31 May 2019 19:30:00 +0100A Repetitive Control- Based Approach for Power Sharing Among Boost Converters in DC Microgrids
http://joape.uma.ac.ir/article_770_144.html
In this paper a repetitive control (RC) approach to improve current sharing between parallel-connected boost converters in DC microgrids is presented. The impact of changes in line impedance on current sharing is investigated. A repetitive controller is designed and connected in series with current controller of the boost converters to control the switching signals such that by regulating of the output voltage of each converter, the circulating current is minimized. The performance of the proposed control strategy is validated through simulation.Mon, 30 Sep 2019 20:30:00 +0100Maximum Power Point Tracker for Photovoltaic Systems Based on Moth-Flame Optimization ...
http://joape.uma.ac.ir/article_771_144.html
The performance of photovoltaic (PV) systems is highly dependent on environmental conditions. Due to probable changes in environmental conditions, the real-time control of PV systems is essential for exploiting their maximum possible power. This paper proposes a new method to track the maximum power point of PV systems using the moth-flame optimization algorithm. In this method, the PV DC-DC converter’s duty cycle is considered as the optimization parameter, and the delivered power of the PV system is maximized in real time. In the proposed approach, some schemes are also employed for detecting condition changes and ignoring small fluctuations of the duty cycle. The results of performance evaluation confirm that the proposed method is very fast, robust, and accurate in different conditions such as standard irradiance and temperature, irradiance and temperature variations, and partial shading conditions. The obtained steady-state efficiency and response time for the introduced method under the standard conditions of the test PV system are 99.68% and 0.021 s, respectively. Indeed, in addition to a relatively good efficiency, the faster response of the introduced tracker is also evident in comparison with other methods.Mon, 30 Sep 2019 20:30:00 +0100Electrical Load Manageability Factor Analyses by Artificial Neural Network Training
http://joape.uma.ac.ir/article_772_144.html
On typical medium voltage feeder, Load side management means power energy consumption controlling at connected loads. Each load has various amount of reaction to essential parameters variation that collection of these reactions is mentioned feeder behavior to each parameter variation. Temperature, humidity, and energy pricing variation or major event happening and power utility announcing to the customers are essential parameters that are considered at recent researches. Depends on amount of improvement that each changeable parameters effect on feeder load consumption, financial assets could be managed correctly to gain proper load side management. Collecting feeder loads behavior to all mentioned parameters will gain Load Manageability Factor (LMF) that helps power utilities to manage load side consumption. Calculating this factor needs to find out each types of load with unique inherent features behavior to each parameters variation. This paper and future works will help us to catch mentioned LMF. In this paper analysis of typical commercial feeder behavior due to temperature and humidity variation with training artificial neural network will be done. Load behavior due to other essential parameters variations like energy pricing variation, major event happening, and power utility announcing to the customers, and etc will study in future worksMon, 30 Sep 2019 20:30:00 +0100A Bi-Level Optimization Approach for Optimal Operation of Distribution Networks with Retailers ...
http://joape.uma.ac.ir/article_773_0.html
Distributed energy resources (DERs) including distributed generators (DGs) and controllable loads (CLs) are managed in the form of several microgrids (MGs) in active distributions networks (ADNs) to meet the demand locally. On the other hand, some loads of distribution networks (DNs) can be supplied by retailers which participate in wholesale energy markets. Therefore, there are several decision makers in DNs which their cooperation should be modeled for optimal operation of the network. For this purpose, a bi-level optimization approach is proposed in this paper to model the cooperation between retailers and MGs in DNs. In the proposed model, the aim of the upper level (leader) and lower level (follower) problems are to maximize the profit of retailers and to minimize the cost of MGs, respectively. To solve the proposed multi-objective bi-level optimization model, multi-objective Particle Swarm Optimization (MOPSO) algorithm is employed. The effectiveness of the proposed bi-level model and its solution methodology is investigated in the numerical results.Fri, 17 May 2019 19:30:00 +0100The Effect of High Penetration Level of Distributed Generation Sources on Voltage Stability ...
http://joape.uma.ac.ir/article_776_144.html
Static voltage stability is considered as one of the main issues for primary identification before voltage collapsing in distribution systems. Although, the optimum siting of distributed generation resources in distribution electricity network can play a significant role in voltage stability improving and losses reduction, the high penetration level of them can lead to reduction in the improvement of load-ability. Moreover, the rapid variation and types of loads in distribution networks will have a significant impact on the maximum load-ability across the whole system. In this paper, a modified voltage stability index is presented with regard to distributed generation units (DG) along with two-tier load model. By applying the Imperialist Competition Algorithm (ICA), the best size of DG with corresponding of DG placement is used to improve the voltage stability and reducing the losses. It is shown in the paper that the DG penetration level can have influence on load-ability of the system and also the voltage regulators performance. The simulation results on the standard IEEE-13 Bus test feeder illustrate the precision of studies method and the load-ability limits in the system, taking into account the high penetration level of distributed generation units.Mon, 30 Sep 2019 20:30:00 +0100Stochastic Assessment of the Renewable-Based Multiple Energy System in the Presence of Thermal ...
http://joape.uma.ac.ir/article_778_0.html
The impact of different energy storages on power systems has become more important due to the development of energy storage technologies. This paper optimizes the stochastic scheduling of a wind-based multiple energy system (MES) and evaluates the operation of the proposed system in combination with electrical and thermal demand-response programs and the three-mode CAES (TM-CAES) unit. The proposed wind-integrated MES consists of a TM-CAES unit, electrical boiler unit, and thermal storage system which can exchange thermal energy with the local thermal network and exchange electricity with the local grid. The electrical and thermal demands as well as wind farm generation are modeled as a scenario-based stochastic problem using the Monte Carlo simulation method. Afterwards, the computational burden is reduced by applying a proper scenario-reduction algorithm to initial scenarios. Finally, the proposed methodology is implemented to a case study to evaluate the effectiveness and appropriateness of the proposed method.Fri, 31 May 2019 19:30:00 +0100Selective Harmonics Elimination Technique in Cascaded Full-Bridge Multi-Level Inverters Using ...
http://joape.uma.ac.ir/article_779_0.html
A new optimization method is proposed in this paper for finding the firing angles in multi-level voltage source inverters to eliminate low-order selective harmonics and reduce total harmonic distortion (THD) value of the output voltage. For thid end, Fourier series is used for calculating objective function and selecting specific harmonics. Regarding the nature and complexity of the employed non-algebraic equations in the optimization problem for achieving the optimal angle in the multi-level inverter, a recent developed meta-heuristic method known as Salp Swarm Algorithm (SSA) is presented. In the proposed method, the optimal angles for a given multi-level inverter are obtained based on the objective function such that the magnitudes of the selective harmonics and the THD value of the output voltage are reduced. The method is applied on a cascaded H-bridge type five-level inverter. The simulation results illustrate that the magnitudes of the selective harmonics and the THD percentage of the output voltage have been reduced through selecting the optimal switching angle by the proposed optimization algorithm. The result of this method are compared with those of SPWM method. Moreover, the performance of SSA algorithm with respect to PSO algorithm is compared which shows its rapid convergence speed and less THD value.Fri, 31 May 2019 19:30:00 +0100Analyzing Impacts of FACTS Devices in Dealing with Short-Term and Long-Term Wind Turbine Faults
http://joape.uma.ac.ir/article_780_144.html
More than one hundred countries are using wind energy due to their easy implementation, cheap energy, and high energy efficiency. Implementation of FACTS devices in Wind Energy Conversion Systems (WECS) has been dramatically improved due to cooperative and accurate performance of FACTS devices. However, dealing with wind turbine faults promptly is crucial. Short-term and long-term faults may have excessive voltage changes and inconstant active and reactive power injection into transmission line. In this paper, robustness and flexibility of SSSC, STATCOM, and UPFC FACTS devices connecting to a 9 MW SCIG-based wind farm under different time-domain fault conditions is investigated. Variety of system scenarios under fault conditions are surveyed in order to find the best Fault Ride Through (FRT) scheme for the system. To carry out this study, same rating and capacity is considered for all three FACTS devices which are employed at the grid-connected point of WECS to mitigate FRT problem. Moreover, the best compromised control mode of FACTS devices is sought by a power flow analysis. Additionally, to obtain a more perceivable view over the technical issues related to the voltage sag support, performance of FACTS devices is analyzed and compared with each other through the paper and at the final stage. A complete digital simulation of the system is executed in the MATLAB/SIMULINK environment and the results are presented to authenticate the performance of devices.Mon, 30 Sep 2019 20:30:00 +0100Stabilizing Microgrid Frequency by Linear Controller Design to Increase Dynamic Response of ...
http://joape.uma.ac.ir/article_781_144.html
In this paper, a distributed generation including diesel generators, wind turbines, and microturbines are introduced, and their mathematical model is described using the Taylor expansion method. With the goal of computational complexity eliminating, the reduced order model (ROM) of microgrid components is considered. The results of the studies indicate that the microgrid frequency is unstable. The main purpose of this paper is stabilizing the frequency of the microgrid by design modified linear controller. It is shown that the using proposed linear controller increases the dynamic response of the diesel generator and therefore can be constituted stable microgrid. The results show that the diesel generator can control the frequency of the microgrid in unwanted islanding and load change conditions. To verify the validity and feasibility of the proposed controller, several simulations results have been presented on MATLAB/Simulink software. The simulation results show the appropriate performance of the proposed controller for example in islanding mode, frequency restoration time is less than 1 (s) by using the proposed controller, as a result, the microgrid can be exploited in island mode.Mon, 30 Sep 2019 20:30:00 +0100Optimal energy management of microgrid in day-ahead and intra-day markets using a copula-based ...
http://joape.uma.ac.ir/article_774_0.html
Recently, economic and environmental problems have created a strong attitude toward utilizing renewable energy sources (RESs). Nevertheless, uncertainty of wind and solar power leads to a more complicated energy management (EM) of RESs in microgrids. This paper models and solves the EM problem of microgrid from the generation point of view. To do this, mathematical formulation of a grid- connected microgrid including wind turbine (WT), photovoltaic (PV), micro turbine (MT), fuel cell (FC) and energy storage system (ESS) is presented. Furthermore an improved incentive-based demand response program (DRP) is applied in microgrid EM problem to flatten the load pattern. Comprehensive studying of EM in both intra-day and day-ahead markets is another contribution of this paper. However, the main novelty of this paper is proposing a new uncertainty modeling technique which is based on copula function and scenario generation. This paper tries to optimize operational cost and environmental pollution as the objective functions and solve them using group search optimization (GSO) algorithm. Numerical results approve the efficiency of the proposed method in solving microgrid EM problem.Fri, 17 May 2019 19:30:00 +0100Energy management of virtual power plant to participate in the electricity market using robust ...
http://joape.uma.ac.ir/article_782_0.html
Virtual power plant (VPP) can be studied to investigate how energy is purchased or sold in the presence of electricity market price uncertainty. The VPP uses different intermittent distributed sources such as wind turbine, flexible loads, and locational marginal prices (LMPs) in order to obtain profit. VPP should propose bidding/offering curves to buy/sell from/to day-ahead market. In this paper, robust optimization approach is proposed to achieve the optimal offering and bidding curves which should be submitted to the day-ahead market. This paper uses mixed-integer linear programming (MILP) model under GAMS software based on robust optimization approach to make appropriate decision on uncertainty to get profit which is resistance versus price uncertainty. The offering and bidding curves of VPP are obtained based on derived data from results. The proposed method, due to less computing, is also easy to trace the problem for the VPP operator. Finally, the price curves are obtained in terms of power for each hour, which operator uses the benefits of increasing or decreasing market prices for its plans. Also, results of comparing deterministic and RO cases are presented. Results demonstrate that profit amount in maximum robustness case is reduced 25.91 % and VPP is resisted against day-ahead market price uncertainty.Fri, 31 May 2019 19:30:00 +0100Recognition and Location of Power Transformer Turn to Turn Fault by Analysis of Winding Imposed ...
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Turn to turn fault is one of the major internal failures in the power transformers that if it is not quickly detected, can be extended and led to a complete transformer breakdown. So, the diagnosis and location of the turn to turn fault of the power transformer, as one of the most important equipment in the power system, is the main objective of this paper. For this purpose, a detailed model of a three-phase transformer is presented by the finite element method (FEM) to investigate this fault in the different situations. Accordingly, the number of short-circuit turns as well as fault location, cause to generate the high forces between the short-circuit turns and the other healthy winding turns. Consequently, in this paper an appropriate method based on force analysis of winding turns for detecting, locating and determining fault severity is introduced.Mon, 30 Sep 2019 20:30:00 +0100FOA: ‘Following’ Optimization Algorithm for solving Power engineering optimization problems
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These days randomized-based population optimization algorithms are in wide use in different branches of science such as bioinformatics, chemical physics andpower engineering. An important group of these algorithms is inspired by physical processes or entities’ behavior. A new approach of applying optimization-based social relationships among the members of a community is investigated in this paper. In the proposed algorithm, search factors are indeed members of the community who try to improve the community by ‘following’ each other. FOA implemented on 23 well-known benchmark test functions. It is compared with eight optimization algorithms. The paper also considers for solving optimal placement of Distributed Generation (DG). The obtained results show that FOA is able to provide better results as compared to the other well-known optimization algorithms.Fri, 31 May 2019 19:30:00 +0100Impact of Demand Response Technique on Hybrid Transmission expansion planning and Reactive ...
http://joape.uma.ac.ir/article_777_0.html
In this paper, a model for hybrid transmission expansion planning (TEP) and reactive power planning (RPP) considering demand response (DR) model has been presented. In this study RPP considered by TEP for its effects on lines capacity and reduction of system expansion costs. On the other hand the expansion of the transmission system is an important subject, especially dealing with the new issues of smart networks like as demand response. Demand response program can change the network expansion planning by shifting elasticity loads and reducing of peak load to improve conditions and decrease the costs. To combine demand response model into the transmission expansion planning and reactive power planning, nonlinear mixed integer meta-heuristic optimization algorithm is used. To evaluate the impact of the proposed expansion planning, this model is exerted to the 30-bus test system. Simulation outcomes display the proposed technique considering demand response model reduces the overall cost of the hybrid TEP-RPP.Fri, 31 May 2019 19:30:00 +0100Compensation of Voltage and Current Harmonics in Hybrid Renewable Energy System Using ...
http://joape.uma.ac.ir/article_768_144.html
In this paper, an adaptive control strategy is proposed for the inverters of renewable energy source (RES) to simultaneously control the load voltage, grid current and the amount of instantaneous injected power to the grid in the presence of grid voltage distortions and nonlinearity of load current. In the proposed control strategy, the power quality of the local load can be settled based on the operator command. In order to implement the proposed control strategy, a cascaded framework of power, voltage and current control has been introduced. An efficient and fast response controller is introduced for the voltage loop, aiming to compensate of harmonics without any complex calculations. The proposed cascade framework is simulated with nonlinear load and non-ideal grid conditions. The simulation results show the effectiveness of the proposed control strategy to not only supply the local load on an appropriate voltage and current quality but also maintaining the amount of injected power at the operator’s desired level.Mon, 30 Sep 2019 20:30:00 +0100A Customer Oriented Approach for Distribution System Reliability Improvement Using Optimal ...
http://joape.uma.ac.ir/article_806_144.html
The reliability of distribution networks is inherently low due to their radial nature, consequently distribution companies (DisCos) usually seek to improve the system reliability indices with the minimum possible investment cost. This can be known as system-oriented reliability planning (SORP). However, there can exist some customers that are not satisfied by their reliability determined by adopting the SORP and they may be eager to have a higher level of reliability. Therefore, other planning in addition of SORP is required to concern the customer viewpoint reliability. This paper introduces the customer-oriented reliability planning (CORP) in medium voltage network which is an innovative approach in the context of load point reliability. To this end, first a SORP is conducted to improve the distribution system reliability index. Then the strategy is revised and the CORP is adopted by DisCo considering involving the results obtained in SORP and the customers that have declared to reduce their expected energy not supplied (EENS). Since the surplus investment cost stem from the planning revision is received from the requestor customers, CORP can provide a proper and acceptable mechanism to fairly allocate the surplus cost to those customers. Furthermore, this problem is studied under the probabilistic nature of distribution network. Simultaneous placement of distributed generators (DGs) and automatic sectionalizing switches is implemented too with a new defined load shedding mechanism in order to enhance the reliability level for both mentioned planning frameworks.Mon, 30 Sep 2019 20:30:00 +0100Multi-Area State Estimation Based on PMU Measurements in Distribution Networks
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State estimation in the energy management center of active distribution networks has attracted many attentions. Considering an increase in complexity and real-time management of active distribution networks and knowing the network information at each time instant are necessary. This article presents a two-step multi-area state estimation method in balanced active distribution networks. The proposed method is based on the location of PMU measurements of the network. The network is divided into several sub-areas about PMUs in the first step. A local sate estimation is implemented in each sub-area. The estimated values of the first step along with real measurements are used as measurements for second step estimation. The measurements are located in each sub-area using these values based on the ellipse area method, and the best location of measurements is extracted. Therefore, a second step state estimation including integrated state estimation of the whole network is performed by using the measurements obtained and located from the first step. The estimation results of the first step are used in the second step which improve the estimation accuracy. Simulations are performed on a standard IEEE 69-bus network to validate the proposed method.Mon, 12 Aug 2019 19:30:00 +0100SCA based Fractional-order PID Controller Considering Delayed EV Aggregators
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The EVs battery has the ability to enhance the balance between the load demand and power generation units. The EV aggregators to manage the random behaviour of EV owners and increasing EVs participation in the ancillary services market are employed. The presence of aggregators could lead to time-varying delay in load frequency control (LFC) schemes. The effects of these delays must be considered in the LFC controller design. Due to the dependency of controller effectiveness on its parameters, these parameters should be designed in such a way that the LFC system has desired performance in the presence of time-varying delay. Therefore, a Sine Cosine Algorithm (SCA) is utilized to adjust the fractional-order PID (FOPID) controller coefficients. Also, some evaluations are performed about the proposed LFC performance by integral absolute error (IAE) indicator. Simulations are carried out in both single and two area LFC system containing EV aggregators with time-varying delay. According to results, the proposed controller has fewer frequency variations in contrast to other controllers presented in the case studies. The obtained output could be considered as a solution to evaluate the proposed controller performance for damping the frequency oscillations in the delayed LFC system.Mon, 12 Aug 2019 19:30:00 +0100Congestion Management through Optimal Allocation of FACTS Devices Using DigSILENT-Based DPSO ...
http://joape.uma.ac.ir/article_809_0.html
Flexible AC Transmission Systems (FACTS) devices have shown satisfactory performance in alleviating the problems of electrical transmission systems. Optimal FACTS allocation problem, which includes finding optimal type and location of these devices, have been widely studied by researchers for improving variety of power system technical parameters. In this paper, a DIgSILENT-based Discrete Particle Swarm Optimization (DPSO) algorithm is employed to manage the power flow, alleviate the congestion, and improve the voltage profile in a real case study. The DPSO have been programmed in DPL environment of DIgSILENT software and applied to the power grid of Gilan Regional Electric Company (GilREC), located in north of Iran. The conducted approach is a user-friendly decision making tool for the engineers of power networks as it is executed in DIgSILENT software which is widely used in electric companies for the power system studies. The simulation results demonstrate the effectiveness of the presented method in improving technical parameters of the test system through several case studies.Mon, 12 Aug 2019 19:30:00 +0100Analysis and Design of a New Single Switch Non-Isolated Buck-Boost dc-dc Converter
http://joape.uma.ac.ir/article_810_0.html
In this paper, a new transformerless buck-boost converter based on ZETA converter is introduced. The proposed converter has the ZETA converter advantages such as, buck-boost capability and input to output DC insulation. The suggested converter voltage gain is higher than the classic ZETA converter. In the presented converter, only one main switch is utilized. The proposed converter offers low voltage stress of the switch; therefore, the low on-state resistance of the main switch can be selected to decrease losses of the switch. The presented converter topology is simple; hence, the control of the converter is simple. The mathematical analyses of the proposed converter are given. The experimental results confirm the correctness of the analysis.Mon, 12 Aug 2019 19:30:00 +0100A model-based PDPC method for control of BDFRG under unbalanced grid voltage condition using ...
http://joape.uma.ac.ir/article_826_0.html
Brushless doubly fed reluctance generator (BDFRG) has been recently suggested as a wind generator. Different control methods are presented in literature for the BDFRG, but there is a gap on control under unbalanced grid voltage condition (UGVC). This paper presents a predictive direct power control (PDPC) method for the BDFRG under UGVC. The proposed PDPC method is based on power compensation strategy, and aims to balance the BDFRG current (strategy I), and to remove the electrical torque pulsation (strategy II). The control objectives are defined using the BDFRG positive sequence (PS) and negative sequence (NS) equations. Then, the active power and reactive power variations are predicted to compute the required voltage for the BDFRG control winding. Finally, the BDFRG is controlled by applying the calculated voltage to the control winding. Simulink toolbox of MATLAB software is used to simulate the system model. Both the proposed PDPC method (with strategies I & II) and the original PDPC method (without a compensation strategy) are applied to control of the BDFRG under UGVC, and the results are compared. The results show the good performance of the proposed PDPC method.Tue, 15 Oct 2019 20:30:00 +0100Multi-Objective Stochastic Programming in Microgrids Considering Environmental Emissions
http://joape.uma.ac.ir/article_827_0.html
This paper deals with day-ahead programming under uncertainties in microgrids (MGs). A two-stage stochastic programming with the fixed recourse approach was adopted. The studied MG was considered in the grid-connected mode with the capability of power exchange with the upstream network. Uncertain electricity market prices, unpredictable load demand, and uncertain wind and solar power values, due to intrinsically stochastic weather changes, were also considered in the proposed method. To cope with uncertainties, the scenario-based stochastic approach was utilized, and the reduction of the environmental emissions generated by the power resources was regarded as the second objective, besides the cost of units’ operation. The ɛ-constraint method was employed to deal with the presented multi-objective optimization problem, and the simulations were performed on a sample MG with one month of real data. The results demonstrated the applicability and effectiveness of the proposed techniques in real-world conditions.Sun, 27 Oct 2019 20:30:00 +0100Active Distribution Networks Restoration after Extreme Events
http://joape.uma.ac.ir/article_828_0.html
After extreme events such as floods, thunderstorms, blizzards and hurricanes there will be devastating effects in the distribution networks which may cause a partial or complete blackout. Then, the major concern for the system operators is to restore the maximum critical loads as soon as possible by available generation units. In order to solve this problem, this paper provides a restoration strategy by using Distributed Generations (DGs). In this strategy, first, the shortest paths between DGs and critical loads are identified. Then, the best paths are determined by using a decision-making method, named PROMOTHEE-II to achieve the goals. The uncertainties for the output power of DGs are also considered in different scenarios. The IEEE 123-node distribution network is used to show the performance of the suggested method. The simulation results clearly show the efficiency of the proposed strategy for critical loads restoration in distribution networks.Tue, 19 Nov 2019 20:30:00 +0100Operation Planning of Wind Farms with Pumped Storage Plants Based on Interval Type-2 Fuzzy ...
http://joape.uma.ac.ir/article_829_0.html
The operation planning problem encounters several uncertainties in terms of the power system’s parameters such as load, operating reserve and wind power generation. The modeling of those uncertainties is an important issue in power system operation. The system operators can implement different approaches to manage these uncertainties such as stochastic and fuzzy methods. In this paper, new fuzzy based modeling approach is implemented to develop the new formulation of power system problems under an uncertain environment with energy storage systems. Interval type-2 fuzzy membership function (MF) is implemented to model the uncertainty of available wind power generation and the type-1 fuzzy MF is used to model the other parameters in weekly unit commitment (UC) problem. The proposed approach is applied to two different test systems which have conventional generating units, wind farms and pumped storage plants to consider differences between the type-1 and type-2 fuzzy approaches for uncertainty modeling. The results show that the total profit of UC problem using type-2 fuzzy MF is better than type-1 fuzzy MF.Tue, 19 Nov 2019 20:30:00 +0100Stochastic Short-Term Hydro-Thermal Scheduling Based on Mixed Integer Programming with Volatile ...
http://joape.uma.ac.ir/article_830_0.html
This study addresses a stochastic structure for generation companies (GenCoʼs) that participate in hydro-thermal self-scheduling with a wind power plant on short-term scheduling for simultaneous reserve energy and energy market. In stochastic scheduling of HTSS with a wind power plant, in addition to various types of uncertainties such as energy price, spinning /non-spinning reserve prices, uncertainties of RESs, such as output power of the wind power plant are also taken into account. In the proposed framework, mixed-integer non-linear programming of the HTSS problem is converted into a MIP. Since the objective of the study is to show how GenCosʼ aim to achieve maximum profit, mixed-integer programming is used here. Therefore, to formulate the MIP for the problem of HTSS with a wind power plant in the real-time modeling, some parameters like the impact of valve loading cost (VLC) that are accompanied by linear modeling, are considered. Furthermore, in thermal units, parameters such as prohibited operating zones (POZs) and different uncertainties like the energy price and wind power are included to formulate the problem more suitably. The point that is worth noting is the use of dynamic ramp rate (DRR). Also, the application of multi-functional curves (L) of hydro plants is considered when studying inter-unit scheduling. Finally, the required tests are conducted on a modified IEEE 118-bus system to verify the accuracy and methodology of the proposed method.Tue, 19 Nov 2019 20:30:00 +0100