Research paper
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.
Research paper
Distribution Systems
M.A. Tavakoli Ghazi Jahani; P. Nazarian; A. Safari; M.R. Haghifam
Abstract
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 ...
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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.
Research paper
Micro Grid
A. Marami Dizaji; M. Saniee; K. Zare
Abstract
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 ...
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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.
Research paper
Micro Grid
M. Zolfaghari; G. B. Gharehpetian; M. Abedi
Abstract
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 ...
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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.
Research paper
Renewable Energy
R. Aghaie; M. Farshad
Abstract
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 ...
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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.
Research paper
Energy Management
N. Eskandari; S. Jalilzadeh
Abstract
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, ...
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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 works
Research paper
Power System Stability
M. Kazeminejad; M. Banejad; U. Annakkage; N. Hosseinzadeh
Abstract
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 ...
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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.
Research paper
Flexible AC TransmissionSystems (FACTs) Devices
A. Shahdadi; B. Z-M-Shahrekohne; S. M. Barakati
Abstract
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, ...
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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.
Research paper
H. Radmanesh; M. Saeidi
Abstract
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 ...
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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.
Research paper
A. Torkaman; V. Naeini
Abstract
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 ...
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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.
Research paper
Micro Grid
M. Shahparasti; P. Teimourzadeh Baboli
Abstract
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. ...
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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.
Research paper
Distribution Systems
P. Salyani; J. Salehi
Abstract
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, ...
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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.
