Electric Mechinces & Drive
M. Moazen; R. Kazemzadeh; M. R. Azizian
Abstract
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) ...
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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.
Distribution Systems
N. Kumar; D.K. Jain
Abstract
The integration of distributed generations (DGs) can disrupt the distribution system's radial configuration, leading to potential coordination issues with the existing protection scheme. Disparate operating modes of microgrids render traditional protection schemes ineffective and insecure. This highlights ...
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The integration of distributed generations (DGs) can disrupt the distribution system's radial configuration, leading to potential coordination issues with the existing protection scheme. Disparate operating modes of microgrids render traditional protection schemes ineffective and insecure. This highlights the need for alternative approaches to ensure the reliability and security of microgrids. To mitigate the relay coordination problem in microgrids, this paper puts forth a solution in the form of an adaptive protection scheme. The proposed method is based on fault current and integrates the use of adaptive numerical directional overcurrent relays (ANDOCRs). The proposed adaptive protection strategy encompasses a microgrid central protection controller (MCPC) equipped with communication capabilities. This feature enables MCPC to communicate with intelligent field electronics devices (IFEDs). The MCPC receives data from the IFEDs and updates the ANDOCRs' settings according to the operation mode. This paper suggests a modified objective function specifically tailored to tackle the nonlinear optimization problem for relay coordination in microgrids to strengthen the coordination between primary and backup relays. The proposed adaptive protection scheme also incorporates a quick online fault detection algorithm to identify the faulty feeder precisely. The proposed method is assessed for its performance using a highly unbalanced IEEE-13 node distribution system in MATLAB/Simulink.
Energy Management
K. Masoudi; H. Abdi
Abstract
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 ...
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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.
Power Electronic
S. Hasanzadeh; S.M. Dehghan; M. Asadi; S.M. Salehi
Abstract
Step-up DC-DC converters are essential components used in a wide range of applications. Many researchers have proposed various methods to achieve high voltage gain in DC-DC converters. However, this typically involves adding multiple passive components, which increases system complexity and complicates ...
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Step-up DC-DC converters are essential components used in a wide range of applications. Many researchers have proposed various methods to achieve high voltage gain in DC-DC converters. However, this typically involves adding multiple passive components, which increases system complexity and complicates output voltage control. Maintaining a constant output voltage at the desired value is critical in these converters despite the load, supply voltage changes, and circuit disturbance. Recently, a snubber-less high-step-up enhanced super-lift converter has been developed as a possible solution to these issues. This converter offers high gain without high voltage stress or snubber losses. A model of the converter was created using the state-space averaging technique and is presented in this paper. The control strategy proposed uses the input current in the inner loop and the output voltage in the outer loop. The paper also includes simulation and experimental results that validate the circuit analysis equations.
Distribution Systems
S. Ghasemi; A. Khodabakhshian; R. Hooshmand
Abstract
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 ...
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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.
Micro Grid
A. Nargeszar; A. Ghaedi; M. Nafar; M. Simab
Abstract
In recent years, the local feeding of the required loads in the micro grids has received much attention comparing to the extension of the large fuel-based power plants, which require the development of costly transmission lines. On the other hand, environmental constraints have led to the increasing ...
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In recent years, the local feeding of the required loads in the micro grids has received much attention comparing to the extension of the large fuel-based power plants, which require the development of costly transmission lines. On the other hand, environmental constraints have led to the increasing development of renewable energy sources that can generate electricity in the form of small-scale generation units in micro grids. In this study, an appropriate mixture of renewable sources incorporating the wind turbines, current type tidal generation units and the photovoltaic systems is integrated to the micro grid connected to the energy storage systems. The proposed micro grid can be customized in the coastal regions and islands for supplying required loads. To optimally determine capacity and size of renewable power plants, different metaheuristic algorithms are applied, and among them, the particle swarm optimization methodology is used to minimize cost function of the system including the investment, operation and the reliability costs. To calculate reliability cost of micro grid, variable hazard rate of the assembled elements influenced by change in air and water temperature, wind velocity, tidal stream velocity and sun irradiance is taken into account. Load curtailment of the micro grid is occurred due to failure of the assembled elements and the change in renewable sources that both are addressed in the paper. For examining effectiveness of proposed approach, numerical results associated to the planning of a micro grid incorporating renewable sources considering the reliability cost are given.
Power Electronic
N. Bagheri; B. Tousi; S.M. Alilou
Abstract
This research offers a high step-up DC-DC converter using a two- winding coupled inductor and voltage multiplier circuit (VMC) including diodes and capacitors for renewable energy (RE) usages such as photovoltaic (PV) and fuel cell (FC). The advantages of this converter are: 1) High voltage gain with ...
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This research offers a high step-up DC-DC converter using a two- winding coupled inductor and voltage multiplier circuit (VMC) including diodes and capacitors for renewable energy (RE) usages such as photovoltaic (PV) and fuel cell (FC). The advantages of this converter are: 1) High voltage gain with small duty cycle of the switch, 2) low voltage stress across switch/diodes, 3) Low number of components, 4) Lower volume and cost, 5) simple structure with only one power switch, 6) small current ripple of the input, 7) zero voltage and current (ZVS and ZCS) of the diodes, 8) improved efficiency, and 9) common grounding of the input and output. Due to the coupled inductor usage, the voltage gain is more flexible, and it can be enhanced by adjusting two different parameters: the turns ratio (N) of the coupled inductor and the duty cycle (D) of the switch. Furthermore, the voltage stresses of the semiconductors are decreased by increasing N. VMC is the other element for the power switch’s voltage stress reduction. The suggested topology could be an appropriate option for RE usage because of the small current ripple of the input and modified efficiency.
Power System Stability
S.K. Gupta; S.K. Mallik
Abstract
Due to the exponential increase in electricity demand, the power system is being operated at its stability limit. Due to the scarcity of natural resources, the generation can not be increased. Hence, there is always a possibility of voltage collapse in the system. The voltage collapse can be predicted ...
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Due to the exponential increase in electricity demand, the power system is being operated at its stability limit. Due to the scarcity of natural resources, the generation can not be increased. Hence, there is always a possibility of voltage collapse in the system. The voltage collapse can be predicted by a number of line stability indices available in the literature. The stress level of the power system can be mitigated by integrating renewable energy resources, such as wind and solar energy. Under heavy loading conditions, the transmission lines get stressful which can be predicted by line voltage stability indices. In this paper, three line stability indices, namely, Lmn, fast voltage stability index (FVSI), and Lqp are used to identify the most stressed lines under four types of system loadings for ensuring the corrective measure to avoid this voltage instability. These indices are being evaluated using continuation power flow. The system loadability and stability are enhanced by deploying the wind energy and solar PV generation at the most appropriate location. The integrated test system includes wind and solar energy systems at one of the most severe bus, and the performance of the system is confirmed by computing the power flow (PF) using the integrated test system's line indices and the power system analysis toolbox (PSAT). The proposed approach has been validated on IEEE 14 and 118-bus test systems in MATLAB/PSAT with the deployment of wind energy and solar energy at a suitable location.
M. Hajibeigy; V. Talavat; S. Galvani
Abstract
Due to ever-increasing energy requirements, modern distribution systems are integrated with renewable energy sources (RESs), such as wind turbines and photovoltaics. They also bring economic, environmental, and technical advantages. However, they face the network operator with decision-making challenges ...
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Due to ever-increasing energy requirements, modern distribution systems are integrated with renewable energy sources (RESs), such as wind turbines and photovoltaics. They also bring economic, environmental, and technical advantages. However, they face the network operator with decision-making challenges due to their uncertain nature. Modern distribution systems usually operate at safety margins, and any contingency may lead to power supply losses. In this regard, any attempts to increase the planner/operator's awareness of the network situation will help improve the decision quality. This paper determines the optimal locations of the RESs to enhance the expected power not served as a reliability index. Besides, it reduces power losses and minimizes the 95\% confidence interval of power losses, as much as possible for having more awareness of network states. The K-medoids data clustering method is applied to handle the uncertainties of the RESs and demand loads. The MOPSO, NSGA II, and MOGWO algorithms are used to solve the proposed problem. The efficiency of the proposed approach is tested on the IEEE standard 33-bus and 118-bus distribution networks. The obtained results show that it is possible to reach a better confidence interval while keeping the losses and reliability index at a desired level. Considering solutions with identical losses and reliability index, the confidence interval of power losses using the MOPSO algorithm is 6.86% and 39.82% better rather than the NSGA II and MOGWO algorithms in the 33-bus distribution network and it is 30.23% and 129.63% better in the 118-bus distribution network.
Electric Mechinces & Drive
V. Naeini; N. Sadeghi
Abstract
This research paper focuses on the optimal configuration of an outer rotor permanent magnet brushless DC (ORBLDC) motor. As torque ripple is a drawback associated with this type of motor, the study proposes an optimal design to minimize torque fluctuations. The proposed design approach considers factors ...
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This research paper focuses on the optimal configuration of an outer rotor permanent magnet brushless DC (ORBLDC) motor. As torque ripple is a drawback associated with this type of motor, the study proposes an optimal design to minimize torque fluctuations. The proposed design approach considers factors such as slot width, pole arc (pole span), the number of slots, and the least common multiple factors between the number of poles and slots. Initially, the machine's parameters and dimensions are determined using design equations, and then different configurations are evaluated using the finite element method to achieve reduced torque fluctuations. The findings demonstrate that the combined design methods employed effectively minimize output torque ripples. Considering various design factors and employing advanced optimal techniques can contribute to the development of more efficient and reliable motor designs as well as reducing torque ripples.
Distribution Systems
S.S. Halve; S.S. Raghuwanshi; D. Sonje
Abstract
Distribution systems play a crucial role in delivering power to customers and bridging the gap between bulk power transmission and end-users. Increasing energy demand due to factors like industrial development and population growth necessitates efficient distribution system management. A low X/R ratio ...
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Distribution systems play a crucial role in delivering power to customers and bridging the gap between bulk power transmission and end-users. Increasing energy demand due to factors like industrial development and population growth necessitates efficient distribution system management. A low X/R ratio in distribution networks leads to higher real power losses, lower voltage profiles, and reduced system reliability. Selecting optimal combinations of sectionalizing and tie switches for network reconfiguration is a complex and time-consuming task. This article introduces the Modified load flow (MLF) method, which combines the backward/forward sweep method with an effective approach for selecting sectionalizing and tie switches to minimize real power loss. The MLF method offers advantages such as ease of implementation, requiring fewer control parameters, and scalability to large distribution systems. The proposed MLF method is compared with particle swarm optimization (PSO) and other existing algorithms in literature such as the cuckoo search algorithm (CSA), Improved sine cosine algorithm (ISCA), and Improved harmony search algorithm (IHSA). Results obtained from MLF and PSO to IEEE-33, 69, and 118 bus radial distribution systems demonstrate significant reductions in real power loss, with MLF outperforming PSO in terms of efficiency and effectiveness. Voltage profiles at critical buses before and after network reconfiguration are examined, showing improvements in MLF better than the PSO method. Various reliability indices are evaluated to assess system performance before and after network reconfiguration, demonstrating improvements in system reliability. Overall, the proposed modified load flow method offers a promising approach to address the challenges of real power losses and system reliability in radial distribution systems.
Distribution Systems
H. Yousefi; S.A. Gholamian; A. Zakariazadeh
Abstract
In this paper, a distributed method for reactive power management in a distribution system has been presented. The proposed method focuses on the voltage rise where the distribution systems are equipped with a considerable number of photovoltaic units. This paper proposes the alternating direction method ...
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In this paper, a distributed method for reactive power management in a distribution system has been presented. The proposed method focuses on the voltage rise where the distribution systems are equipped with a considerable number of photovoltaic units. This paper proposes the alternating direction method of multipliers (ADMMs) approach for solving the optimal voltage control problem in a distributed manner in a distribution system with high penetration of PVs. Also, the proposed method uses a clustering approach to divide the network into partitions based on the coupling degrees among different nodes. The optimal reactive power control strategy is conducted in each partition and integrated using ADMM. The proposed method is tested on a 33 bus IEEE distribution test system and a modified IEEE 123-node system. The result evidence that the proposed method has used the lower reactive power if compared to the conventional method.
Planing & Reliability
A. Ghaedi; R. Sedaghati; M. Mahmoudian
Abstract
In many different nations around the world, renewable energy sources are increasingly being used to generate electricity. It is because renewable resources are sustainable, have no operating costs, and are environmentally friendly. Wind power develops quickly among renewable units, and nowadays, several ...
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In many different nations around the world, renewable energy sources are increasingly being used to generate electricity. It is because renewable resources are sustainable, have no operating costs, and are environmentally friendly. Wind power develops quickly among renewable units, and nowadays, several wind farms with large installed capacity are operating in the world. However, the erratic property of wind velocity causes generated power of wind parks to vary, which has an impact on various parts of electric network connected to wind parks and needs to be studied using new methods. In order to address reliability-based operation studies of electric network in presence of wind parks, the current research suggests a method taking into account both probabilistic and deterministic approaches for reserve scheduling. The PJM method has been modified for this reason, for incorporating wind production into the electric network. For wind farms, a several-state reliability presentation that considers hazard of assembled elements and change in produced power is developed at first stage. The appropriate amount of spinning reserve is then computed using matrix multiplication method through modified PJM methodology. Numerical simulations related to reliability test networks are provided for assessing efficacy of suggested methodology. It is concluded from numerical outcomes that the wind farms lead to the reduction of required spinning reserve. However, due to the variation of output power of wind farms arisen from variation of wind velocity, the impact of wind units in reduction of spinning reserve is less than the conventional units with the same capacity. Besides, spinning reserve calculated by well-being approach of wind farms that combines the probabilistic and deterministic indices is more accurate than the value obtained by risk indices.
Distribution Systems
A. Khorshidi; T. Niknam; B. Bahmani
Abstract
In this work, a new control scheme for synchronization of AC microgrids with upstream power grid is presented. The effects of V2Gs (vehicle to grid) dynamics on synchronization process is studied. This new control approach is based on the optimal fractional calculus and has been developed for synchronization ...
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In this work, a new control scheme for synchronization of AC microgrids with upstream power grid is presented. The effects of V2Gs (vehicle to grid) dynamics on synchronization process is studied. This new control approach is based on the optimal fractional calculus and has been developed for synchronization of the microgrid. The V2Gs effect on the dynamics of the microgrid is analyzed through small signal stability and simulations. This effect is also considered in synchronization process by considering a PHEV-dominated-microgrid. The proposed control scheme is a coordinated control of distributed resources and provides a soft and reliable synchronization for microgrid. In the proposed control scheme, the fractional order proportional-integral-derivative (FOPID) controllers have optimally been tuned and implemented using the genetics algorithm (GA). The simulation results confirm the effectiveness of the proposed control strategy in soft and swift synchronization of the microgrid.
A. Nateghi; H. Shahsavari
Abstract
In this paper, the theory and modeling of large scale photovoltaic (PV) in the power grid and its effect on power system stability are studied. In this work, the basic module, small signal modeling and mathematical analysis of the large scale PV jointed multi-machine are demonstrated. The principal portion ...
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In this paper, the theory and modeling of large scale photovoltaic (PV) in the power grid and its effect on power system stability are studied. In this work, the basic module, small signal modeling and mathematical analysis of the large scale PV jointed multi-machine are demonstrated. The principal portion of the paper is to reduce the low frequency fluctuations by tuned stabilizer in the attendance of the PV unit. In order to optimize the system performance, a novel optimal fuzzy based fractional order PID ( ) stabilizers are proposed to meliorate small signal stability of a power network connected PV unit. For optimizing the performance of the system, is exploited by Gray Wolf Optimization (GWO) algorithm. In order of evaluation of the proposed stabilizers performance, two different types of controllers are compared, include optimal classic stabilizer and based particle swarm optimization (PSO) algorithm. The superiority of based GWO on improving small signal stability in the studied system, including large scale PV is shown via time-domain simulations.
Electric Mechinces & Drive
A. Younesi; S. Tohidi; M.R. Feyzi
Abstract
Model predictive control (MPC) based methods are gaining more and more attention in power converters and electrical drives. Nevertheless, high computational burden of MPC is an obstacle for its application, especially when the prediction horizon increases extends. At the same time, increasing the prediction ...
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Model predictive control (MPC) based methods are gaining more and more attention in power converters and electrical drives. Nevertheless, high computational burden of MPC is an obstacle for its application, especially when the prediction horizon increases extends. At the same time, increasing the prediction horizon leads to a superior response. In this paper, a long horizon MPC is proposed to control the power converter employed in the rotor side of DFIG. The main contribution of this paper is to propose a new comparative algorithm to speed up the optimization of the objective function. The proposed algorithm prevents examining all inputs in each prediction step to saving the computational time. Additionally, the proposed method along with the use of an incremental algorithm applies a sequence of weighting factors in the cost function over the prediction horizon to maximize the impact of primary samples on the optimal vector selection. Therefore, the proposed MPC strategy can predict a longer horizon with relatively low computational burden. Finally, results show that the proposed controller has the fastest dynamic response with lower overshoots compared to direct torque control and vector control method. In addition, the proposed strategy with more accurate response reduces the calculation time by up to 48% compared to classical MPC, for the prediction horizon of three.
Energy Management
G.R Aghajani; I. Heydari
Abstract
Microgrid and smart electrical grids are among the new concepts in power systems that support new technologies within themselves. Electric cars are some advanced technologies that their optimized use can increase grid efficiency. The modern electric cars sometimes, through the necessary infrastructure ...
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Microgrid and smart electrical grids are among the new concepts in power systems that support new technologies within themselves. Electric cars are some advanced technologies that their optimized use can increase grid efficiency. The modern electric cars sometimes, through the necessary infrastructure and proper management, can serve as an energy source to supply grid loads. This study was conducted to investigate the energy management for production and storage resources. For this purpose, we considered the market price of energy, the prices quoted by distributed generation sources, and electric vehicles in the grid and responsive loads. The load response programs used include the time of use and direct load control. The problem has a linear mixed-integer planning structure that was simulated using the GAMS software. The results show that with this planning, the proposed load response programs have a positive impact on cost reduction.
Power Electronic
F. Mohammadi; J. Milimonfared; H. Rastegar; M. Farhadi-Kangarlu
Abstract
A new single-phase transformerless grid-connected PV inverter is presented in this paper. Investigations in transformerless grid-connected PV inverters indicate the existence of the leakage current is directly related to the variable common-mode voltage (CMV), which is presented in detail. On the other ...
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A new single-phase transformerless grid-connected PV inverter is presented in this paper. Investigations in transformerless grid-connected PV inverters indicate the existence of the leakage current is directly related to the variable common-mode voltage (CMV), which is presented in detail. On the other hand, in recent years it has become mandatory for the transformerless grid-connected PV inverters to satisfy new grid-codes such as low-voltage ride-through (LVRT) capability via injecting reactive power during grid faults. Therefore, in this paper, the design of the proposed topology is based on retaining the constant CMV to suppress the leakage current and also to provide reactive power injection capability during grid faults. The control strategies for injecting reactive power in the LVRT condition are also examined. To validate the presented theoretical concepts, the performance and dynamic response of the proposed transformerless PV inverter are investigated by MATLAB/Simulink and the simulation results are presented and discussed.
Energy Management
M. Azimi; A. Salami
Abstract
This study presents an optimal framework for the operation of integrated energy systems using demand response programs. The main goal of integrated energy systems is to optimally supply various demands using different energy carriers such as electricity, heating, and cooling. Considering the power market ...
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This study presents an optimal framework for the operation of integrated energy systems using demand response programs. The main goal of integrated energy systems is to optimally supply various demands using different energy carriers such as electricity, heating, and cooling. Considering the power market price, this work investigates the effects of multiple energy storage devices and demand response programs, including the time of use pricing, real-time pricing, and integrated demand response on optimal operation of energy hub. Moreover, impacts of different optimization methods are evaluated on the optimal scheduling of multi-carrier energy systems. Maximizing profits of selling electrical energy and minimizing the purchasing cost of input carrier energies are considered as objective functions to indicate bidirectional interchanges of energy hub systems with the power grid. To minimize the generation cost of energy carriers, a new quadratic objective function is also optimized using genetic algorithm. In this study, optimal operation of the energy hub based on the proposed quadratic objective function is an economic dispatch problem where the purchasing electrical power by the energy hub is considered as a load of the upstream grid. The optimization problem is implemented in the sample energy hub to indicate the effectiveness of different energy storage roles and applied demand response programs in the optimal operation of energy hub systems.
A. Potfode; S. Bhongade
Abstract
With day by day increase in electrical energy demand and uneven distribution of sources in nature, there is a need of Integration of power plants. This integration needs a proper scheduling of all connected generating units in accordance with the variation in load demand. An optimum sharing of load is ...
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With day by day increase in electrical energy demand and uneven distribution of sources in nature, there is a need of Integration of power plants. This integration needs a proper scheduling of all connected generating units in accordance with the variation in load demand. An optimum sharing of load is necessary to minimize the generation cost. Emission is also an important issue in a generation. An attempt is also made in this paper to analyze emission dispatch with the Economic Dispatch optimization. Environmental effects tend to involve renewable sources based power generation. Wind and Solar are most popular and highly abundant among all renewable sources. But, the fluctuations of these sources complicate the load dispatch optimization. Also, the conventional thermal generators itself affected by certain constraints and non linearity such as valve-point loading effect. A proper planning should involve consideration of all this issue, which requires advance soft computing technique. Previous approaches need proper tuning of their specific parameters, to remove this ambiguity, a new Jaya Algorithm technique is introduced in this paper.
A. Gholipour; M. Ghanbari; E. Alibeiki; M. Jannati
Abstract
Current sensors are required in Field-Oriented Control (FOC) strategies of Three-Phase Induction Motor (TPIM) drives. Nevertheless, the current sensors are subject to different electrical/mechanical faults which reduce the safety and dependability of the drive system. Single phase current sensor Fault-Tolerant ...
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Current sensors are required in Field-Oriented Control (FOC) strategies of Three-Phase Induction Motor (TPIM) drives. Nevertheless, the current sensors are subject to different electrical/mechanical faults which reduce the safety and dependability of the drive system. Single phase current sensor Fault-Tolerant Control (FTC) for sensorless TPIM drives using flux observer and Extended Kalman Filter (EKF) is proposed in this research. In the suggested FTC scheme, current sensor fault detection is based on axes transformation, a logic circuit is served as the fault isolation and reconstruction of faulted currents are achieved through flux observer and EKF. The presented FTC system is capable of detecting and localizing the current sensor fault and switching the drive system to tolerant FOC mode without the rotor speed measurement. The effectiveness of the suggested FTC system is confirmed by experiments on a 0.75kW TPIM drive platform.
R. Behkam; A. Moradzadeh; H. Karami; M.S. Nadery; B. Mohammadi ivatloo; G.B. Gharehpetian; S. Tenbohlen
Abstract
The Frequency Response Analysis (FRA) technique has advantages in identifying faults related to power transformers, but it suffers from the interpretation of frequency responses. This paper presents an approach based on statistical indices and Artificial Neural Network (ANN) methods to interpret frequency ...
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The Frequency Response Analysis (FRA) technique has advantages in identifying faults related to power transformers, but it suffers from the interpretation of frequency responses. This paper presents an approach based on statistical indices and Artificial Neural Network (ANN) methods to interpret frequency responses. The proposed procedure divides frequency responses into four frequency regions based on frequency resonances and anti-resonances. Then, Lin’s Concordance Coefficient (LCC) index is used as one of the most appropriate numerical indices to extract features of the four frequency regions. Finally, the Multilayer Perceptron (MLP) neural network is trained by the extracted features to identify and differentiate the types of winding faults. Besides, other intelligent algorithms such as Support Vector Machine (SVM), Extreme Learning Machine (ELM), Probabilistic Neural Network (PNN), and Radial Basis Function (RBF) neural network have been employed to compare the classification results. The proposed techniques have been practically implemented. The Axial Displacement (AD) and Disk Space Variation (DSV) faults are applied as two common mechanical faults in different locations and intensities on the 20kV windings of a 1.6MVA distribution power transformer and their corresponding frequency responses are calculated. Frequency responses calculated from the AD and DSV faults constitute the MLP input data set. The network is trained with part of the input data, and the rest of the data is allocated to validate and test the network. The results show that the suggested method has more proper performance than others using the phase component of the frequency responses in interpreting frequency responses and separation and identifying various mechanical fault types of transformer windings.
A. Jasemi; H. Abdi
Abstract
As a basic tool in power system control and operation, the optimal power flow (OPF) problem searches the optimal operation point via minimizing different objectives and maintaining the control variables within their applicable regions. In recent years, this problem has encountered many challenges due ...
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As a basic tool in power system control and operation, the optimal power flow (OPF) problem searches the optimal operation point via minimizing different objectives and maintaining the control variables within their applicable regions. In recent years, this problem has encountered many challenges due to the presence of renewable energy sources, which has led introducing of a combinatorial type of power networks known as AC/DC hybrid power systems. In this paper, the OPF problem is proposed in an AC/DC hybrid microgrid, including wind power plants. For the first time, the mentioned problem is considered as a multi-objective optimization problem via minimizing fuel cost and emission. The problem is modeled while considering the power flow equations, the voltage limits in AC and DC buses, the AC voltage angle limits, and the firing angle of the converters. Also, due to the uncertain power generated by wind power plants, the probabilistic OPF problem is modeled by the five-point estimation method. To solve the problem, the "fmincon" function in MATLAB software is used by applying the IP algorithm. The simulation case study on a 13-bus sample MG verifies the effectiveness of the proposed method. The numerical results confirm that increasing the wind farm capacity from 14.54 MW to 113 MW, will be led to increasing the fuel cost from 10% to 61%, in case of including the power losses compared to the condition in which they are neglected. It is also observed that in terms of different weights, the total air pollution including the power losses is 2.30 to 2.40 times higher than the total pollution without electrical losses
A. Komijani; M. Kheradmandi; M. Sedighizadeh
Abstract
Voltage drop during the fault can be effected on the performance of generation units such as wind turbines. The ability to ride through the fault is important for these generation units. Superconducting fault current limiter and superconducting magnetic energy storage can improve the fault ride through ...
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Voltage drop during the fault can be effected on the performance of generation units such as wind turbines. The ability to ride through the fault is important for these generation units. Superconducting fault current limiter and superconducting magnetic energy storage can improve the fault ride through due to fault current limiting and voltage restoring ability during the fault, respectively. This paper presents a method for optimal allocation and control of superconducting magnetic energy storage and superconducting fault current limiters in meshed microgrids. For this purpose, the doubly-fed induction generator voltage deviation, the point of common coupling power deviation, the fault current of transmission lines, and superconducting fault current limiter and superconducting magnetic energy storage characteristics were considered as objective functions. In this paper, the optimization is performed in single-step and two-step by particle swarm optimization algorithm, and the system with the optimal superconducting magnetic energy storage and superconducting fault current limiters are analyzed and compared. The results of simulations show superconducting fault current limiter and superconducting magnetic energy storage reduce 85% of voltage drop, decreases 63% of doubly fed induction generator power deviation, and limits the maximum fault current of transmission lines by 9.8 pu. Finally, the status of the studied system variables has been investigated, in two scenarios related to the different fault locations with equipment that the optimal allocated.
J. Borsalani; A. Dastfan; J. Ghalibafan
Abstract
The parasitic parameters of an IGBT power module cause various problems, especially for electromagnetic compatibility (EMC) concerns. The high-variations in voltage and current produced by the inductances/capacitances near switches in the transient process are the main sources of high-frequency electromagnetic ...
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The parasitic parameters of an IGBT power module cause various problems, especially for electromagnetic compatibility (EMC) concerns. The high-variations in voltage and current produced by the inductances/capacitances near switches in the transient process are the main sources of high-frequency electromagnetic interference (EMI). To overcome the problems, the parasitic parameters of the module should be accurately characterized. In this paper, a precise detailed model of a commercial half-bridge IGBT module is presented. It includes the parasitic inductances of leads, bond wires, DBC plates, and the parasitic capacitances of the module and IGBTs. The new simplified analytical equations to calculate the partial inductance and parasitic capacitance are proposed and compared with ANSYS Q3D results. To evaluate the accuracy of the model, all the parameters are also derived from a two-port measurement-based parasitic extraction method. The results show an acceptable match between the simulated and experimental values. Finally, the proposed model is implemented by state-space dynamic coupling in ANSYS Simplorer circuit simulator, and a double-pulse test circuit is used to verify the model. By comparing the simulated current and voltage waveforms with experiment, it is proved that the proposed model is applicable to simulate the switching transients for EMC study.
