Mojtaba Najafi - Academia.edu (original) (raw)
Papers by Mojtaba Najafi
International Transactions on Electrical Energy Systems, 2021
This paper presents the optimal and intelligent design of photovoltaic-wind-hydrogen system with ... more This paper presents the optimal and intelligent design of photovoltaic-wind-hydrogen system with the aim of minimizing the overall cost of the system and considering the reliability constraints based on annual radiation and wind speed data in Bushehr city. The hydrogen storage system includes an electrolyzer, a hydrogen storage tank and a fuel cell. Overall costs of hybrid systems include initial investment costs, maintenance and operation and replacement of components, and reliability constraint indicate deficit load demand probability (DLDP). In this study, the decision variables were optimized system capacity including number of solar panels, wind turbine, electrolyzer power capacity, mass of hydrogen storage tank, fuel cell capacity and power transfered with inverter by Grey Wolf Optimization (GWO) algorithm that has high convergence speed and accuracy. System design is presented in different scenarios of hybrid system combinations. To verify the proposed method, the results are...
In this paper, a method is presented to maximize the revenue from price difference due to the pre... more In this paper, a method is presented to maximize the revenue from price difference due to the presence of storage systems in the power system with a high penetration level of wind resources. To account for price changes due to the profitability of price differences, a two-level model is presented that maximizes the earnings from price differences and has been carried out at a low level of market-clearing procedure. The high level uses low-level production prices and adjusts the storage outputs that affect the low-level price. Conversion techniques have been used for single-line programming with respect to system balance constraints. In order to check the performance, the proposed method will be implemented on the IEEE 118 bus test network. Analyzing the results revealed that the proposed method has improved significantly compared with the traditional method and has been able to achieve higher arbitrage income. By applying a two-level model can soften clearly the marginal price by lo...
Journal of Iranian Association of Electrical and Electronics Engineers, 2013
دنك . نيدب هك تسا تردق هكبش رد ديلوت يفداصت تارييغت ندرك ظاحل ،لوا فده تنوم شور و يفداصت هيوست لد... more دنك . نيدب هك تسا تردق هكبش رد ديلوت يفداصت تارييغت ندرك ظاحل ،لوا فده تنوم شور و يفداصت هيوست لدم كي زا روظنم تسا هدش هدافتسا ولراك . هرهب ،مود فده رد تيفرظ صاصتخا دنيآرف رد اهنآ نانيمطا تيلباق و يديلوت ياهدحاو زا يداصتقا يرادرب يم رارق رظندم ،اهروتارنژ هب هريخذ و يژرنا رازاب زاين دروم دريگ . هنيزه رب هولاع ،هطوبرم فده عبات رد ،هريخذ و يژرنا نيمات ياه هنيزه مدع ياه ين هريخذ و يژرنا ليوحت هديدرگ ظاحل ز دنا . يم يداهنشيپ شور ياهيجورخ رد مزلا ياهقوشم داجيا دنيآرف رد دناوت دوش هتفرگ راكب ناگدننك ديلوت نيب . هدننك ديلوت هكارچ دوخ هب ار رازاب زا يرتشيب مهس ،دشاب هتشاد يرتلااب نانيمطا تيلباق هك يا داد دهاوخ صاصتخا . كبش كي يور رب هدش هئرا شور يياراك تسا هدش هئارا نآ جياتن و هتفرگ رارق يبايزرا دروم هنومن ه .
Australian Journal of Basic and Applied Sciences, 2011
SSRN Electronic Journal, 2022
Ain Shams Engineering Journal, 2021
Abstract Value of the lost load (VOLL) is a useful quantity in economical evaluations of power sy... more Abstract Value of the lost load (VOLL) is a useful quantity in economical evaluations of power systems. The VOLL depends on multiple factors such as type of customer, regional economic conditions and demographics, time and duration of outage, and other specific traits of power interruption. The reviewed literatures show that there are still issues which could be considered in estimation of the VOLL, especially for industrial customers. One of the most interesting issues is inclusion of reliability of an industrial plant in estimation of the VOLL. This means that how reliability data of the plant components (failure rates, repair time, etc.) can be incorporated in the studies to provide a probabilistic model for the VOLL and its related quantities. This paper incorporates failure probability in the VOLL estimation of an industrial plant. For this purpose, firstly an estimate for failure rate of the plant components is obtained and secondly, this estimate is applied in failure probability function which is to be incorporated in the VOLL. Results provide a probabilistic model for the VOLL.
There is an increasing trend in consideration of the electricity-supply quality in modern power s... more There is an increasing trend in consideration of the electricity-supply quality in modern power systems. One of the quality-related aspects is the desired level of reliability at the points of electrical-energy consumption or load points. In this regard, the system operator needs to evaluate the impact of system components on the reliability at the considered load points. “Reliability importance” is a quantitative index in order to measure this impact. The reliability importance measure in most of the conventional methods is on the basis of the risk sensitivity analysis. Such an analysis imposes prohibitive computational burden in large power systems. Considering these points, this paper proposes an approach to evaluate the reliability importance which is not suffered from the immense computational burden. The proposed method determines reliability importance of the electrical-energy producers or generators from the consumers or load points perspective in a selected area of the powe...
Electrical Engineering, 2021
Intelligent electric distribution networks compensated with D-STATCOM are active networks in whic... more Intelligent electric distribution networks compensated with D-STATCOM are active networks in which data of terminals is important for better distribution of energy. Similar to all electricity network devices, energy distribution lines in such networks are also subject to transient and steady-state AC faults, e.g., short circuit. Sections of the network in which the fault occurs are separated by relays. In such a condition, fault location and restoring the normal status of the network are important. Fault location in these networks is performed based on synchronous data of two terminals because data of all buses are transmitted to the main bus In this paper, a time-domain equation method (TDEM) is proposed for locating faults on smart distribution grid (SDG) using distributed line model based on time-domain equations. The proposed method locates the point of transient and steady-state fault in SDG considering DGs and compensators. In this paper, the D-STATCOM and wind power plant are considered in SDG. The suggested method does not need the D-STATCOM and DGs model for applying the algorithm. It only uses data of less than half of the cycle for executing the algorithm. The numerical simulation confirms that the proposed fault location method is accurate and it provides a reliable solution for automatic fault location problem in distribution networks.
2021 International Conference on Recent Advances in Mathematics and Informatics (ICRAMI), 2021
In designing engineering systems, definitive solutions can hardly be applied to actual scenarios.... more In designing engineering systems, definitive solutions can hardly be applied to actual scenarios. This issue is mainly originated from production constraints and the environmental conditions of the actual systems under exploitation. Therefore, a small change in the design variables vector may lead to a significant change in the optimal design that minimizes the objective functions. Hence, it is important to develop methods that provide optimal (or even sub-optimal) solutions with less sensitivity to the uncertainty of the design variables. This is the focus of this paper. We present a robust Non-dominated-Sorting Genetic Algorithm II (NSGA-II)-based multi-objective constrained optimization algorithm. To further illustrate the method, the proposed algorithm is used in the robust and constrained optimal design of a sample engineering system. Evaluation of the obtained results shows that multi-objective engineering problems can be solved by the multi-objective robust optimization (MORO) through finding Pareto solutions, so that by changing the problem parameters, the changes of the solutions will be within an acceptable range.
Electrical Engineering, 2021
One of the important factors in the discussion of power transmission is filling the capacity of n... more One of the important factors in the discussion of power transmission is filling the capacity of network lines, which limits the transmission of power and increases the locational marginal price (LMP) in the network. Today, one of the techniques for resolving congestion and reducing LMP is to install DG units in the network, taking into account two factors: place and optimal size of DG based on operating costs and network constraints, all of which depend on the awareness of the capacity of network lines. In this article, in the first step, using the GA-GSF algorithm, identifying the network's weaknesses such as the lines that have reached their maximum capacity, and then by considering three terms and two scenarios condition of the buses connected to the filled lines will be discussed and we review and extract the best places for installing DG on the network. Then, considering the cost of operating DG and applying it to the objective function of the problem, by positively denoting DG profit and reducing line congestion, the optimization problem is solved by GA-GSF algorithm, and finally, the algorithm output including place and optimal size of DG unit in the network is minimized by line congestion and LMP, and DG installation is economically justified. Finally, the proposed algorithm was tested on the IEEE 14-BUS network for seven different DG types, and the results were such that out of these seven DGs, three DGs were able to reduce the total capacity of the network lines to less than the full capacity of the lines and the price of LMP has been raised to the price of UMP, and the other four DGs have managed to lower the price of LMP compared to their cost function.
International Transactions on Electrical Energy Systems, 2021
This paper presents the optimal and intelligent design of photovoltaic-wind-hydrogen system with ... more This paper presents the optimal and intelligent design of photovoltaic-wind-hydrogen system with the aim of minimizing the overall cost of the system and considering the reliability constraints based on annual radiation and wind speed data in Bushehr city. The hydrogen storage system includes an electrolyzer, a hydrogen storage tank and a fuel cell. Overall costs of hybrid systems include initial investment costs, maintenance and operation and replacement of components, and reliability constraint indicate deficit load demand probability (DLDP). In this study, the decision variables were optimized system capacity including number of solar panels, wind turbine, electrolyzer power capacity, mass of hydrogen storage tank, fuel cell capacity and power transfered with inverter by Grey Wolf Optimization (GWO) algorithm that has high convergence speed and accuracy. System design is presented in different scenarios of hybrid system combinations. To verify the proposed method, the results are...
In this paper, a method is presented to maximize the revenue from price difference due to the pre... more In this paper, a method is presented to maximize the revenue from price difference due to the presence of storage systems in the power system with a high penetration level of wind resources. To account for price changes due to the profitability of price differences, a two-level model is presented that maximizes the earnings from price differences and has been carried out at a low level of market-clearing procedure. The high level uses low-level production prices and adjusts the storage outputs that affect the low-level price. Conversion techniques have been used for single-line programming with respect to system balance constraints. In order to check the performance, the proposed method will be implemented on the IEEE 118 bus test network. Analyzing the results revealed that the proposed method has improved significantly compared with the traditional method and has been able to achieve higher arbitrage income. By applying a two-level model can soften clearly the marginal price by lo...
Journal of Iranian Association of Electrical and Electronics Engineers, 2013
دنك . نيدب هك تسا تردق هكبش رد ديلوت يفداصت تارييغت ندرك ظاحل ،لوا فده تنوم شور و يفداصت هيوست لد... more دنك . نيدب هك تسا تردق هكبش رد ديلوت يفداصت تارييغت ندرك ظاحل ،لوا فده تنوم شور و يفداصت هيوست لدم كي زا روظنم تسا هدش هدافتسا ولراك . هرهب ،مود فده رد تيفرظ صاصتخا دنيآرف رد اهنآ نانيمطا تيلباق و يديلوت ياهدحاو زا يداصتقا يرادرب يم رارق رظندم ،اهروتارنژ هب هريخذ و يژرنا رازاب زاين دروم دريگ . هنيزه رب هولاع ،هطوبرم فده عبات رد ،هريخذ و يژرنا نيمات ياه هنيزه مدع ياه ين هريخذ و يژرنا ليوحت هديدرگ ظاحل ز دنا . يم يداهنشيپ شور ياهيجورخ رد مزلا ياهقوشم داجيا دنيآرف رد دناوت دوش هتفرگ راكب ناگدننك ديلوت نيب . هدننك ديلوت هكارچ دوخ هب ار رازاب زا يرتشيب مهس ،دشاب هتشاد يرتلااب نانيمطا تيلباق هك يا داد دهاوخ صاصتخا . كبش كي يور رب هدش هئرا شور يياراك تسا هدش هئارا نآ جياتن و هتفرگ رارق يبايزرا دروم هنومن ه .
Australian Journal of Basic and Applied Sciences, 2011
SSRN Electronic Journal, 2022
Ain Shams Engineering Journal, 2021
Abstract Value of the lost load (VOLL) is a useful quantity in economical evaluations of power sy... more Abstract Value of the lost load (VOLL) is a useful quantity in economical evaluations of power systems. The VOLL depends on multiple factors such as type of customer, regional economic conditions and demographics, time and duration of outage, and other specific traits of power interruption. The reviewed literatures show that there are still issues which could be considered in estimation of the VOLL, especially for industrial customers. One of the most interesting issues is inclusion of reliability of an industrial plant in estimation of the VOLL. This means that how reliability data of the plant components (failure rates, repair time, etc.) can be incorporated in the studies to provide a probabilistic model for the VOLL and its related quantities. This paper incorporates failure probability in the VOLL estimation of an industrial plant. For this purpose, firstly an estimate for failure rate of the plant components is obtained and secondly, this estimate is applied in failure probability function which is to be incorporated in the VOLL. Results provide a probabilistic model for the VOLL.
There is an increasing trend in consideration of the electricity-supply quality in modern power s... more There is an increasing trend in consideration of the electricity-supply quality in modern power systems. One of the quality-related aspects is the desired level of reliability at the points of electrical-energy consumption or load points. In this regard, the system operator needs to evaluate the impact of system components on the reliability at the considered load points. “Reliability importance” is a quantitative index in order to measure this impact. The reliability importance measure in most of the conventional methods is on the basis of the risk sensitivity analysis. Such an analysis imposes prohibitive computational burden in large power systems. Considering these points, this paper proposes an approach to evaluate the reliability importance which is not suffered from the immense computational burden. The proposed method determines reliability importance of the electrical-energy producers or generators from the consumers or load points perspective in a selected area of the powe...
Electrical Engineering, 2021
Intelligent electric distribution networks compensated with D-STATCOM are active networks in whic... more Intelligent electric distribution networks compensated with D-STATCOM are active networks in which data of terminals is important for better distribution of energy. Similar to all electricity network devices, energy distribution lines in such networks are also subject to transient and steady-state AC faults, e.g., short circuit. Sections of the network in which the fault occurs are separated by relays. In such a condition, fault location and restoring the normal status of the network are important. Fault location in these networks is performed based on synchronous data of two terminals because data of all buses are transmitted to the main bus In this paper, a time-domain equation method (TDEM) is proposed for locating faults on smart distribution grid (SDG) using distributed line model based on time-domain equations. The proposed method locates the point of transient and steady-state fault in SDG considering DGs and compensators. In this paper, the D-STATCOM and wind power plant are considered in SDG. The suggested method does not need the D-STATCOM and DGs model for applying the algorithm. It only uses data of less than half of the cycle for executing the algorithm. The numerical simulation confirms that the proposed fault location method is accurate and it provides a reliable solution for automatic fault location problem in distribution networks.
2021 International Conference on Recent Advances in Mathematics and Informatics (ICRAMI), 2021
In designing engineering systems, definitive solutions can hardly be applied to actual scenarios.... more In designing engineering systems, definitive solutions can hardly be applied to actual scenarios. This issue is mainly originated from production constraints and the environmental conditions of the actual systems under exploitation. Therefore, a small change in the design variables vector may lead to a significant change in the optimal design that minimizes the objective functions. Hence, it is important to develop methods that provide optimal (or even sub-optimal) solutions with less sensitivity to the uncertainty of the design variables. This is the focus of this paper. We present a robust Non-dominated-Sorting Genetic Algorithm II (NSGA-II)-based multi-objective constrained optimization algorithm. To further illustrate the method, the proposed algorithm is used in the robust and constrained optimal design of a sample engineering system. Evaluation of the obtained results shows that multi-objective engineering problems can be solved by the multi-objective robust optimization (MORO) through finding Pareto solutions, so that by changing the problem parameters, the changes of the solutions will be within an acceptable range.
Electrical Engineering, 2021
One of the important factors in the discussion of power transmission is filling the capacity of n... more One of the important factors in the discussion of power transmission is filling the capacity of network lines, which limits the transmission of power and increases the locational marginal price (LMP) in the network. Today, one of the techniques for resolving congestion and reducing LMP is to install DG units in the network, taking into account two factors: place and optimal size of DG based on operating costs and network constraints, all of which depend on the awareness of the capacity of network lines. In this article, in the first step, using the GA-GSF algorithm, identifying the network's weaknesses such as the lines that have reached their maximum capacity, and then by considering three terms and two scenarios condition of the buses connected to the filled lines will be discussed and we review and extract the best places for installing DG on the network. Then, considering the cost of operating DG and applying it to the objective function of the problem, by positively denoting DG profit and reducing line congestion, the optimization problem is solved by GA-GSF algorithm, and finally, the algorithm output including place and optimal size of DG unit in the network is minimized by line congestion and LMP, and DG installation is economically justified. Finally, the proposed algorithm was tested on the IEEE 14-BUS network for seven different DG types, and the results were such that out of these seven DGs, three DGs were able to reduce the total capacity of the network lines to less than the full capacity of the lines and the price of LMP has been raised to the price of UMP, and the other four DGs have managed to lower the price of LMP compared to their cost function.