Behnam Alizadeh; Shahram Jadid
Volume 2, Issue 1 , June 2007, , Pages 1-9
Abstract
This paper presents an application of Benders decomposition to deal with the complexities in the simultaneous Generation Expansion Planning (GEP) and Transmission Expansion Planning (TEP). Unlike the power system operation fields of study, the power system planning methods are not expected to be fast. ...
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This paper presents an application of Benders decomposition to deal with the complexities in the simultaneous Generation Expansion Planning (GEP) and Transmission Expansion Planning (TEP). Unlike the power system operation fields of study, the power system planning methods are not expected to be fast. However, it is always preferable to speed up computations to provide more analysis options for the planner. In this study, Benders decomposition has been applied to solve a mixed integer linear programming formulation of simultaneous GEP & TEP problem. The method has been tested on two test systems: Garver 6-bus system and IEEE 30-bus system. The results are compared to the unified solution of the problem formulation to show the consequent improvements from Benders decomposition.
R. Kazemzadeh; M. Moazen; R. Ajabi-Farshbaf; M. Vatanpour
Volume 1, Issue 1 , June 2013, , Pages 1-11
Abstract
In this paper, a combinational optimization algorithm is introduced to obtain the best size and location of Static Compensator (STATCOM) in power systems. Its main contribution is considering contingency analysis where lines outages may lead to infeasible solutions especially at peak loads and it commonly ...
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In this paper, a combinational optimization algorithm is introduced to obtain the best size and location of Static Compensator (STATCOM) in power systems. Its main contribution is considering contingency analysis where lines outages may lead to infeasible solutions especially at peak loads and it commonly can be vanished by load-shedding. The objective of the proposed algorithm is firstly to prevent infeasible power flow solutions without undesired load-shedding, which is critical in contingency analysis; and secondly to mitigate overall power losses and costs. Moreover, active and reactive powers generation costs are considered in the proposed objective function. Since there are various constraints such as lines outages number, cost and their duration that must be taken to account, Bacterial Foraging oriented by Particle Swarm Optimization (BF-PSO) algorithm combined with Optimal Power Flow (OPF) is used to solve and overcome the complexity of this combinational nonlinear problem. In order to validate the accuracy of the proposed method, two test systems, including IEEE 30 bus standard system and Azarbaijan regional power system of Iran, are applied in simulation studies. All obtained optimization results show the effectiveness of the suggested combinational method in loss and cost reduction and preventing load-shedding.
Application of Automatic Control in Power System
N. Zendehdel
Volume 3, Issue 1 , June 2015, , Pages 1-22
Abstract
This paper presents a comprehensive robust distributed intelligent control for optimum self-healing activities in smart distribution systems considering the uncertainty in loads. The presented agent based framework obviates the requirements for a central control method and improves the reliability of ...
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This paper presents a comprehensive robust distributed intelligent control for optimum self-healing activities in smart distribution systems considering the uncertainty in loads. The presented agent based framework obviates the requirements for a central control method and improves the reliability of the self-healing mechanism. Agents possess three characteristics including local views, decentralizations and autonomy. The message, exchanged among neighboring agents, is used to develop a global information discovery algorithm and updates the topology information of out-of-service areas, available supply capacity and routing information. Fuzzy description is employed to take into account the uncertainties of measurements in which are exchanged between agents. Moreover, to find the optimal restoration plan, incorporating the discovered data, a routing problem is developed as a fuzzy binary linear optimization problem. This problem is approached by a novel method using a specific ranking function. Finally, robustness and applicability of the proposed self-healing method is tested on two standard case studies. The obtained results emphasize that ignoring the uncertainties may lead to non-realistic solutions.
Dynamics
M. Sadeghi; M. Kalantar
Volume 4, Issue 1 , June 2016, , Pages 1-15
Abstract
This study presents a dynamic way in a DG planning problem instead of the last static or pseudo-dynamic planning point of views. A new way in modeling the DG units’ output power and the load uncertainties based on the probability rules is proposed in this paper. A sensitivity analysis on the stochastic ...
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This study presents a dynamic way in a DG planning problem instead of the last static or pseudo-dynamic planning point of views. A new way in modeling the DG units’ output power and the load uncertainties based on the probability rules is proposed in this paper. A sensitivity analysis on the stochastic nature of the electricity price and global fuel price is carried out through a proposed model. Six types of clean and conventional DG units are included in the planning process. The presented dynamic planning problem is solved considering encouraging and punishment functions. The imperialist competitive algorithm (ICA) as a strong evolutionary strategy is employed to solve the DG planning problem. The proposed models and the proposed problem are applied on the 9-bus and 33-bus test distribution systems. The results show a significant improvement in the total revenue of the distribution system in all of the defined scenarios.
Energy Management
A. Hatefi einaddin; A. Sadeghi Yazdankhah; R. Kazemzadeh
Abstract
As an efficient alternative to fossil fuels, renewable energy sources have attained great attention due to their sustainable, cost-effective, and environmentally friendly characteristic. However, as a deficiency, renewable energy sources have low reliability because of their non-deterministic and stochastic ...
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As an efficient alternative to fossil fuels, renewable energy sources have attained great attention due to their sustainable, cost-effective, and environmentally friendly characteristic. However, as a deficiency, renewable energy sources have low reliability because of their non-deterministic and stochastic generation pattern. The use of hybrid renewable generation systems along with the storage units can mitigate the reliability problem. Hence, in this paper, a grid connected hybrid micro-grid is presented, which includes wind and photovoltaic resources as the primary power sources and a hydrogen storage system (including fuel cell and electrolyzer) as a backup. A new power management strategy is proposed to perform a proper load sharing among the micro-grid units. Hybrid (distributed/central) control method is applied for the realization of the control objectives such as DC bus voltage regulation, power factor control, synchronous grid connection, and power fluctuation suppression. Distributed controllers have the task of fulfilling local control objectives such as MPPT implementation and storage unit control. On the other hand, the central control unit is mainly responsible for power management in the micro-grid. Performance and effectiveness of the proposed power management strategy for the presented micro-grid are verified using a simulation study.
Distribution Systems
R. Afshan; J. Salehi
Abstract
This paper proposes a novel hybrid Monte Carlo simulation-genetic approach (MCS-GA) for optimal operation of a distribution network considering renewable energy generation systems (REGSs) and battery energy storage systems (BESSs). The aim of this paper is to design an optimal charging /discharging scheduling ...
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This paper proposes a novel hybrid Monte Carlo simulation-genetic approach (MCS-GA) for optimal operation of a distribution network considering renewable energy generation systems (REGSs) and battery energy storage systems (BESSs). The aim of this paper is to design an optimal charging /discharging scheduling of BESSs so that the total daily profit of distribution company (Disco) can be maximized. In this study, the power generation of REGSs such as photovoltaic resources (PVs) and the network electricity prices are studied through their uncertainty natures. The probability distribution function (PDF), is used to account for uncertainties in this paper. Also, the Monte Carlo simulation (MCS) is applied to generate different scenarios of network electricity prices and solar irradiation of PVs. Optimal scheduling of BESSs can be performed by genetic algorithm (GA). In this paper, firstly, the charging and discharging state of BESSs (positive or negative sign of battery power) is determined according to the variable amount of the electricity prices and power produced from PVs, which have been obtained from the Monte Carlo simulation. Then by using the GA, optimal amount of BESSs is determined. Therefore, a hybrid MCS-GA is used to solve this problem. Numerical examples are presented to illustrate the optimal charging/discharging power of the battery for maximizing the total daily profit.
Power Electronic
M. Farhadi-Kangarlu; F. Mohammadi
Abstract
The single-phase transformerless grid-connected photovoltaic (PV) systems, mainly the low-power single-phase systems, require high efficiency, small size, lightweight, and low-cost grid-connected inverters. However, problems such as leakage current, the DC current injection and safety issues are incorporated ...
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The single-phase transformerless grid-connected photovoltaic (PV) systems, mainly the low-power single-phase systems, require high efficiency, small size, lightweight, and low-cost grid-connected inverters. However, problems such as leakage current, the DC current injection and safety issues are incorporated with transformerless grid-connected PV inverters. Besides, the new standards such as Low-Voltage Ride-Through (LVRT) capability and staying connected to the grid during the fault occurrence should be considered for the next generation of transformerless PV inverters. In this paper, a study is going underway on the LVRT capability and the Common-Mode Voltage (CMV) in a number of most common transformerless grid-connected PV inverters. In fact, by a comprehensive study on all possible switching combinations and the current paths during the freewheeling period of the selected inverters, the proposed control strategy for performance improvement of the PV inverters under the normal and the LVRT conditions is presented. As a matter of fact, a reconfigurable PWM method is proposed, which makes it possible to switch between two PWM methods and hence provide improved performance of the inverters in the LVRT condition. Finally, the results of simulations in the normal and the LVRT operations to verify the theoretical concepts are indicated.
N. Afsari; S.J. SeyedShenava; H. Shayeghi
Abstract
The inevitable emergence of intelligent distribution networks has introduced new features in these networks. According to most experts, self-healing is one of the main abilities of smart distribution networks. This feature increases the reliability and resiliency of networks by reacting fast and restoring ...
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The inevitable emergence of intelligent distribution networks has introduced new features in these networks. According to most experts, self-healing is one of the main abilities of smart distribution networks. This feature increases the reliability and resiliency of networks by reacting fast and restoring the critical loads (CLs) during a fault. Nevertheless, the stochastic nature of the components in a power system imposes significant computational risk in enabling the system to self-heal. In this paper, a mathematical model is introduced for the self-healing operation of networked Microgrids (MGs) to assess the risk in the optimal service restoration (SR) problem. Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) and their stochastic nature besides the distributed generation units (DGs), the ability to reconfiguration, and demand response program are considered simultaneously. The objective function is designed to maximize the restored loads and minimize the risk. The Conditional Value-at-Risk (CVaR) is used to calculate the risk of the SR as one of the most efficient and famous risk indices. In the general case study and considering $\beta $ equal to the 0, 1, 2, 3, and 4, expected values of SR for the risk-averse problem is 21.2, 20, 19.3, 19.1, and 19\% less than the risk-neutral problem, respectively. The formulation of the problem is mixed-integer linear programming (MILP), and the model is tested in the modified Civanlar test system. The analysis of several case studies has proved the performance of the proposed model and the importance of risk management in the problem.
H. Bahlouli; A. Mansouri; M. Bouhamida
Abstract
The high cost and complexity of using sensors for controlling processes have led to the development of observer techniques that aim to estimate system states without the need for sensors. These techniques reduce system complexity and can potentially reduce product and maintenance costs. In this paper, ...
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The high cost and complexity of using sensors for controlling processes have led to the development of observer techniques that aim to estimate system states without the need for sensors. These techniques reduce system complexity and can potentially reduce product and maintenance costs. In this paper, we present an interconnected high gain observer (IHGO) that estimates the electromagnetic torque, speed, and position of a doubly fed induction generator-based wind turbine (DFIG-WT) using only voltage, current, and wind speed measurements. The IHGO is designed to be robust to parameter uncertainties and its stability is assessed using Lyapunov theory. To guarantee finite time convergence, a Super Twisting-based High Order Sliding Mode (ST-HOSM) controller is used for direct torque control. The ST-HOSM is a simple algorithm that maintains the sliding mode characteristics, provides robustness against disturbance, and reduces the chattering phenomenon. The controller and observer are designed in the $\alpha\beta$ frame to avoid the use of a phase-locked loop (PLL). Simulation results confirmed the effectiveness of the proposed control strategy under parameter uncertainties, power and speed variations, grid voltage dip and current sensor noise.
M. Mirzaie; A. Azizi Tousi
Volume 1, Issue 2 , November 2013, , Pages 74-83
Abstract
One of the important factors influencing outdoor insulators performance is pollution phenomenon. The pollution, especially during humidity condition, reduces superficial resistance of insulator and lead to a flow of Leakage Currents (LC) on the insulator surface, which may result in total flashover. ...
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One of the important factors influencing outdoor insulators performance is pollution phenomenon. The pollution, especially during humidity condition, reduces superficial resistance of insulator and lead to a flow of Leakage Currents (LC) on the insulator surface, which may result in total flashover. The LC characteristics are affected by parameters such as nature and severity of pollution. Location of pollution is another parameter that can be effective. This paper presents the analysis of LC waveforms of insulator strings under different pollution location and Equivalent Salt Deposit Density (ESDD). The tests was performed on the HV porcelain suspension insulator string in which three adjacent discs of insulator string were contaminated and location of them changes along the insulator string. Besides, the effect of humidity and operating voltage on LC waveforms were investigated. Experimental data were analyzed in both time and frequency domain. Obtained results indicate that there is strong correlation between the location of pollution and LC parameters such as peak value ( ), harmonic components and Total Harmonic Distortion (THD). Also, the ratio of fifth to third harmonic component ( ) is presented as an important index that has strong relationship to the pollution location.
Ebrahim Babaei; S. Laali; M.B.B. Sharifian
Volume 2, Issue 2 , December 2014, , Pages 81-90
Abstract
In this paper, a new cascaded multilevel inverter by capability of increasing the number of output voltage levels with reduced number of power switches is proposed. The proposed topology consists of series connection of a number of proposed basic multilevel units. In order to generate all voltage levels ...
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In this paper, a new cascaded multilevel inverter by capability of increasing the number of output voltage levels with reduced number of power switches is proposed. The proposed topology consists of series connection of a number of proposed basic multilevel units. In order to generate all voltage levels at the output, five different algorithms are proposed to determine the magnitude of DC voltage sources. Reduction of the used power switches and the variety of DC voltage sources magnitudes are two main advantages of the proposed topology. These results are obtained by comparison of the proposed inverter with the H-bridge cascaded multilevel inverter and one of recently presented topologies. The remarkable ability of the proposed topology with its algorithms in generating all voltage levels (even and odd) is verified through PSCAD/EMTDC simulation and experimental results of a 17-level inverter.
I. Sepehrirad; R. Ebrahimi; E. Alibeiki; S. Ranjbar
Abstract
Modern power systems deal with different stability concerns due to operation near to their critical margins. Implementing the small energy resources and online islanding schemes perform as a modification scheme for increasing the system overall stability. This paper presents an adaptive approach for ...
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Modern power systems deal with different stability concerns due to operation near to their critical margins. Implementing the small energy resources and online islanding schemes perform as a modification scheme for increasing the system overall stability. This paper presents an adaptive approach for online detection of islanding microgirds in the presence of renewable energy resources consisting of diesel generators. For this issue, based on the concept of thevenin impedance, the microgrid impedance matrix is evaluated. In this case, considering the system angular frequency as an online index within different operating conditions, the islanding operating cases are identified. The proposed scheme uses an online non-model-based index which provides high impedance values in the case of grid-connected operating mode. Through continuous time window, the system impedance derivatives-based matrix is provided which islanding operating scenarios are estimated. In this case, considering a set of analytical evaluations, the required adaptive parameters and corresponding online adjustments are provided. The proposed approach is carried out through a modified microgrid test system consisting of synchronous generators which considering different cases studies, the proposed scheme ability is evaluated. It is revealed that through different case studies about 100 ms time duration is required to estimate an islanding operating condition which the proposed MICI index goes lower than criteria. Simulation results dedicate the effectiveness of the proposed approach for online and fast identification of islanding scenarios with respect to other corresponding techniques.
Distribution Systems
A. Lashkar Ara; H. Bagheri Tolabi; R. hosseini
Volume 4, Issue 2 , December 2016, , Pages 93-103
Abstract
In this paper, a combination of simulated annealing (SA) and intelligent water drops (IWD) algorithm is used to solve the nonlinear/complex problem of simultaneous reconfiguration with optimal allocation (size and location) of wind turbine (WT) as a distributed generation (DG) and dynamic voltage restorer ...
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In this paper, a combination of simulated annealing (SA) and intelligent water drops (IWD) algorithm is used to solve the nonlinear/complex problem of simultaneous reconfiguration with optimal allocation (size and location) of wind turbine (WT) as a distributed generation (DG) and dynamic voltage restorer (DVR) as a distributed flexible AC transmission systems (DFACT) unit in a distribution system. The objectives of this research are to minimize active power loss, minimize operational cost, improve voltage stability, and increase the load balancing of the system. For evaluation purposes, the proposed algorithm is evaluated using the Tai-Power 11.4-kV real distribution network. The impacts of the optimal placement of the WT, DVR, and WT with DVR units are separately evaluated. The results are compared in terms of statistical indicators. By comparing all the testing scenarios, it is observed that the multi-objective optimization evolutionary algorithm is more beneficial than its single-objective optimization counterpart. Also, the obtained results show that the proposed SAIWD method outperforms the IWD method and other intelligent search algorithms such as genetic algorithm or particle swarm optimization.
Electric Mechinces & Drive
H Nazari; N. Rostami
Volume 3, Issue 2 , December 2015, , Pages 94-101
Abstract
This paper presents a method for diagnosis of eccentricity fault in a switched-reluctance motor (SRM) during offline and standstill modes. In this method, the fault signature is differential induced voltage (DIV) achieved by injecting diagnostic pulses to the motor windings. It will be demonstrated by ...
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This paper presents a method for diagnosis of eccentricity fault in a switched-reluctance motor (SRM) during offline and standstill modes. In this method, the fault signature is differential induced voltage (DIV) achieved by injecting diagnostic pulses to the motor windings. It will be demonstrated by means of results that there is a correlation between differential induced voltage and eccentricity occurrence. The method employs three-dimensional transient finite-element method (TFEM) analysis to calculate differential induced voltage in three phase 6/4 SRM. In this method, first of all the fault presence is distinguished. Next, an algorithm is presented for the detection of fault location or faulty phase. Then, the direction of fault is recognized by a simple comparative technique, and finally, results comparing is proposed to detect fault type.
Power Electronic
M. Heidari; M. A. Shams Nejad; M. Monfared
Abstract
Because of installation for local consumers and since it is free of all contaminations, connecting photovoltaic cells to the grid via single-phase inverter is significantly on the rise. In this paper, a new simple current control is proposed for a single-phase grid-connected voltage source inverter. ...
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Because of installation for local consumers and since it is free of all contaminations, connecting photovoltaic cells to the grid via single-phase inverter is significantly on the rise. In this paper, a new simple current control is proposed for a single-phase grid-connected voltage source inverter. Using the PQ theory and modelling a single-phase system as an unbalanced three-phase system, a method is provided for reference current generation. In the proposed method, it is not necessary to generate a fictitious phase for the current signal. Also, the removal of adjusting filter parameters which were used to generate fictitious current signal increases the simplicity of the control system and reduces computational efforts, especially in the presence of distortion in the current. The simulation results confirm that the proposed method provides a precise and fast current control with minimum harmonic distortions.
Long and Short Term Operation
F. Jabari; B. Mohammadi ivatloo; M. B. Bannae Sharifian; H. Ghaebi
Abstract
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 ...
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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.
Electric Mechinces & Drive
H. Afsharirad; M. B. B. Sharifian; M. Sabahi; S. H. Hosseini
Abstract
A dual mechanical port machine (DMPM) is used as an electrically variable transmission (EVT) in hybrid electric vehicle (HEV). In the conventional HEV, this machine is replaced by a planetary gearbox and two electric machines and makes this structure simpler. This paper presents field oriented control ...
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A dual mechanical port machine (DMPM) is used as an electrically variable transmission (EVT) in hybrid electric vehicle (HEV). In the conventional HEV, this machine is replaced by a planetary gearbox and two electric machines and makes this structure simpler. This paper presents field oriented control (FOC) for DMPM. For HEV application, drive efficiency and wide operating speed range are important. The control strategy, which uses the maximum torque per ampere (MTPA) method at low speed and flux weakening (FW) method at high speed are proposed. The model of DMPM considering the magnetic coupling between two air gaps has been developed in MATLAB/Simulink and the proposed control strategy is applied to DMPM. The simulation results have been provided with a brief discussion at the end.
Power System Operation
H. Siahkali
Abstract
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 ...
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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.
H. Shayeghi; S. Pourjafar; S.M. Hashemzadeh; F. Sedaghati
Abstract
In this article, a novel topology of DC-DC converter based on voltage multiplier cell and coupled inductor with higher efficiency and low blocking voltage across semiconductor is proposed for renewable energy application. The recommended topology obtains a high voltage gain using voltage multiplier cell ...
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In this article, a novel topology of DC-DC converter based on voltage multiplier cell and coupled inductor with higher efficiency and low blocking voltage across semiconductor is proposed for renewable energy application. The recommended topology obtains a high voltage gain using voltage multiplier cell and one coupled inductor. Only one power switch is utilized in this structure, which reduces the converter's cost. The other benefits of this converter are low number of components, high efficiency due to the zero-voltage switching and the zero-current switching of diodes, and low blocking voltage of the power switch and diodes. Besides, the voltage multiplier cell acts as a passive clamp circuit and reduces the voltage stress across the power switch. Thus, a low rated power switch can be used in the presented topology. Due to the zero-current switching in Off-state, the reverse recovery problem of diodes is reduced. To illustrate the performance and superiority of the presented topology, operation modes, steady-state and efficiency analysis, and the comparison study with other similar converters are presented. Finally, a 160~W experimental prototype with 50~kHz switching frequency and 17 V input voltage are built to confirm the theoretical investigation and effectiveness of the proposed converter.
G.R. Goyal; S. Vadhera
Abstract
Supply-side energy management (SSEM) aims to improve efficiency in operations and strategic planning. Both the cost of generating electricity and the amount of emissions from that generation are minimized in SSEM. It is required to formulate an optimization problem with these two competing goals in order ...
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Supply-side energy management (SSEM) aims to improve efficiency in operations and strategic planning. Both the cost of generating electricity and the amount of emissions from that generation are minimized in SSEM. It is required to formulate an optimization problem with these two competing goals in order to come up with a compromise. Resolving problems with network reliability caused by peak demand on the electricity system is another goal of SSEM. The ultimate goal of this study is to reduce energy use during peak hours while also cutting down on power losses, generation costs, and pollution from power plants. In this paper all goals of the smart grid system are satisfied and addressed optimally through the use of optimal generator scheduling and an improved demand response technique. To formulate this problem standard IEEE 30-bus system is considered as test boat. The suggested system employs the Cuckoo search method and its most recent variant, adaptive Cuckoo search, to solve a stochastic non-linear optimization problem. The adaptive Cuckoo search approach, when combined with the proposed demand side management strategy, reduces fuel costs by 7.84%, emission dispatch by 16.35%, power losses by 10.31%, and peak hour demand by 15.6%.
R. Baghipour; S.M. Hosseini
Volume 2, Issue 1 , June 2007, , Pages 10-21
Abstract
In practical situations, distribution network loads are the mixtures of residential, industrial, and commercial types. This paper presents a hybrid optimization algorithm for the optimal placement of shunt capacitor banks in radial distribution networks in the presence of different voltage-dependent ...
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In practical situations, distribution network loads are the mixtures of residential, industrial, and commercial types. This paper presents a hybrid optimization algorithm for the optimal placement of shunt capacitor banks in radial distribution networks in the presence of different voltage-dependent load models. The algorithm is based on the combination of Genetic Algorithm (GA) and Binary Particle Swarm Optimization (BPSO) algorithm. For this purpose, an objective function including the cost of energy loss, reliability, and investment cost of the capacitor banks is considered. Also, the impacts of voltage-dependent load models, considering annual load duration curve, is taken into account. In addition, different types of customers such as industrial, residential, and commercial loads are considered for load modeling. Simulation results for 33-bus and 69-bus IEEE radial distribution networks using the proposed method are presented and compared with the other methods. The results showed that this method provided an economical solution for considerable loss reduction and reliability and voltage improvement.
Power System Operation
A. Rabiee
Abstract
- Power system state estimation is a central component in energy management systems of power system. The goal of state estimation is to determine the system status and power flow of transmission lines. This paper presents an advanced state estimation algorithm based on weighted least square (WLS) ...
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- Power system state estimation is a central component in energy management systems of power system. The goal of state estimation is to determine the system status and power flow of transmission lines. This paper presents an advanced state estimation algorithm based on weighted least square (WLS) criteria by introducing virtual meters. For each bus of network, except slack bus, a virtual meter is considered, using the concept of KCL law. Regarding virtual meter, an improved state estimation algorithm is obtained with higher accuracy and lower computation burden. In the case study, at first, a simple 6-bus test system is presented and the proposed state estimation algorithm is followed step by step. Then, in order to evaluate the effectiveness and applicability of algorithm, IEEE 30-bus and IEEE 118-bus test systems are also taken into consideration. The obtained results verify the usefulness of the proposed method in large size power systems including thousands of buses.
J. Moshtagh; S. Ghasemi
Volume 1, Issue 1 , June 2013, , Pages 12-21
Abstract
In this paper, a Non-dominated Sorting Genetic Algorithm-II (NSGA-II) based approach is presented for distribution system reconfiguration. In contrast to the conventional GA based methods, the proposed approach does not require weighting factors for conversion of multi-objective function into an equivalent ...
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In this paper, a Non-dominated Sorting Genetic Algorithm-II (NSGA-II) based approach is presented for distribution system reconfiguration. In contrast to the conventional GA based methods, the proposed approach does not require weighting factors for conversion of multi-objective function into an equivalent single objective function. In order to illustrate the performance of the proposed method, 33-bus and 69-bus distribution networks have been employed which have led to the desired results.
Power Quality
A. ِDeihimi; A. Rahmani
Abstract
An intelligent method based on wavelet neural network (WNN) is presented in this study to estimate voltage harmonic distortion waveforms at a non-monitored sensitive load. Voltage harmonics are considered as the main type of waveform distortion in the power quality approach. To detect and analyze voltage ...
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An intelligent method based on wavelet neural network (WNN) is presented in this study to estimate voltage harmonic distortion waveforms at a non-monitored sensitive load. Voltage harmonics are considered as the main type of waveform distortion in the power quality approach. To detect and analyze voltage harmonics, it is not economical to install power quality monitors (PQMs) at all buses. The cost associated with the monitoring procedure can be reduced by optimizing the number of PQMs to be installed. The main aim of this paper is to further reduce the number of PQMs through recently proposed optimum allocation approaches. An estimator based on WNN is presented in this study to estimate voltage-harmonic waveforms at a non-monitored sensitive load using current and voltage at a monitored location. Since capacitors and distributed generations (DGs) have a special role in distribution networks, they are considered in this paper and their effects on the harmonic voltage waveform estimator are evaluated. The proposed technique is examined on the IEEE 37-bus network. Results indicate the acceptable high accuracy of the WNN estimator.
F. Khalafian; A. Saffarian
Abstract
Existing generators used in renewable wind Turbines (WT) that are connected to the power system at the distribution level need a sound power grid for proper operation. The purpose of this article is to simultaneously use Unified Power Quality Conditioner (UPQC), wind turbine and appropriate control system ...
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Existing generators used in renewable wind Turbines (WT) that are connected to the power system at the distribution level need a sound power grid for proper operation. The purpose of this article is to simultaneously use Unified Power Quality Conditioner (UPQC), wind turbine and appropriate control system to achieve the lowest harmonic distortion and voltage drop during network faults. Also, in this article, in order to check the efficiency of different fact tools when there is a fault in the network, a comparison between UPQC performance with static VAR compensator (SVC) and distribution synchronous static compensator (D-STATCOM) was made and the obtained results were presented. The performed simulations are based on compensation of voltage decrease and increase as well as compensation of harmonic distortion caused by nonlinear loads. The results obtained in this article show that Using UPQC in the network was able to compensate for 100% of voltage drop and voltage increase in the network, while svc and D-Statcom equipment in the best case compensated for 98\% of voltage increase and 90\% of voltage decrease. UPQC also can be the best tool to eliminate network flow harmonics. In the previous papers, the best value for harmonic current distortion was 1.67%, but our results showed that the harmonic distortion of the network current when using UPQC is 1.47%. Also the harmonic distortion of network current with SVC and D-Statcom is 5.67 and 4.87 percent, respectively. The capability of the equipment in compensating for short circuit fault current and protection of wind power plant is also evaluated. There was no change in wind turbine voltage during the use of UPQC and faults, and 1 P.U remained constant, but when using svc and D-Statcom equipment, the wind turbine voltage during the fault decreased by 0.3 and 0.5 P.U respectively.
