Power systems
Milad Niaz Azari; Iraj Ahmadi; Hossein Aboulqasemi
Abstract
In this paper, the loss of excitation fault (LOE) as one of the most common fault in synchronous generator is analyzed and the methods for detecting this fault are investigated. Then, the performance of the power system equipped with STATCOM is simulated in the Matlab / Simulink software and the effects ...
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In this paper, the loss of excitation fault (LOE) as one of the most common fault in synchronous generator is analyzed and the methods for detecting this fault are investigated. Then, the performance of the power system equipped with STATCOM is simulated in the Matlab / Simulink software and the effects of the generator performance on the resistor and its derivatives in the generator terminal are analyzed. A new method for LOE detection based on derivative of resistance is proposed. To illustrate the efficiency of this method various sizes and conditions for generator load are considered. The simulation results show that the amount of resistance time derivative in all cases, whether with or without STATCOM, behaves the same as a new criterion for detecting the LOE of an effective and useful method that is faster and more accurate than conventional methods. Simulation results in different amount and type of the loads shows the validity of the proposed method.
Optimization
Mina Salarian; Milad Niaz Azari; Mostafa Haji aghai
Abstract
One of the important issues in designing high-performance brushless direct current (BLDC) motors is reducing the cogging torque since it results in mechanical vibration, audible noises, and torque ripples, which adversely impact the performance of the motor, which is awkward high-accuracy applications. ...
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One of the important issues in designing high-performance brushless direct current (BLDC) motors is reducing the cogging torque since it results in mechanical vibration, audible noises, and torque ripples, which adversely impact the performance of the motor, which is awkward high-accuracy applications. This paper proposes an optimum design for BLDC motors aimed at reducing the cogging torque based on the capability of metaheuristics algorithms in finding the optimal solution. For this purpose, a simplified cogging torque equation is used as the objective function whose design variables include air gap length, magnet height, slot height, slot opening, and motor axial length. These are the five most influential parameters of cogging torque. On the other hand, we employ not only the old metaheuristics algorithms like the Genetic Algorithm (GA) and Simulated Annealing (SA) but also more recent algorithms such as Keshtel Algorithm (KA) along with the hybrid ones to benefit from their strength. The simulation is performed in the Matlab package. First, five selected optimization algorithms are applied and the results are investigated. The results of all the algorithms show a significant reduction in the cogging torque. Eventually, the proposed algorithms are compared to one another in terms of their value of cogging torque. The results show the superiority of the KASA algorithm in comparison with the others.
Power systems
Milad Niaz Azari; Reza Fathi shoob
Abstract
Synchronous generators are one of the most important components of power systems. Problems a generator may face are internal faults, system disturbances, or operational hazards. The operation of a generator may easily be affected by faults within the machine itself as opposed to external disturbances ...
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Synchronous generators are one of the most important components of power systems. Problems a generator may face are internal faults, system disturbances, or operational hazards. The operation of a generator may easily be affected by faults within the machine itself as opposed to external disturbances occurring on the network to which it is connected. Generator protection must therefore be designed to react efficiently in both conditions. Loss of excitation (LOE) is a common fault in synchronous generators. The most common causes of LOE include the loss of field to the main exciter, accidental tripping of the field breaker, short circuits in the field circuit, and poor brush contact in the exciter. The most widely applied method to detect a generator loss of field condition on major generators is the use of distance relays to sense the variations of impedance as viewed from the generator terminals. This approach may not be able to distinguish between LOE and stable power swing (SPS). This paper further explores a new method proposed for LOE detection and corrects its shortcomings. It also presents a new approach for LOE detection that exploits a combined scheme based on the derivative of the terminal voltage and the derivative power angle of the generator. Comprehensive simulation studies are conducted on various generator conditions and system disturbances to determine the relay setting and to evaluate its performance. These studies demonstrate that the proposed strategy enhances the security and operation time of the LOE relay compared with some existing methods.
Optimization
Milad Niaz Azari; Vasiye Lohrasbi; Seyed Abdolah Mousavi
Abstract
Today, with the high promotion of technology and the expansion of industries, electric motors are used extensively and consume a large part of the electrical energy produced by power plants. Therefore, researchers and experts have always sought solutions to make electric motors with high reliability ...
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Today, with the high promotion of technology and the expansion of industries, electric motors are used extensively and consume a large part of the electrical energy produced by power plants. Therefore, researchers and experts have always sought solutions to make electric motors with high reliability and low losses. The machines are made of a high temperature superconducting motor with high efficiency are called high temperature superconductor -induction synchronous motor (HTS-ISM). In this paper, the high-temperature superconducting induction/synchronous motor (HTS-ISM) is studied. Optimizing of torque density and the structural dimensions of HTS-ISM is done using one of the newest optimization methods, the collective decision optimization algorithm (CDOA). The results show a torque of about 51.75% increase via the optimization process. Also commonly used optimization method, particle swarm optimization algorithm (PSO) method was implemented to compare the results. The comparison has proved that the CDOA method high capability to optimize the motor design parameters. All of the algorithms in this paper is performed with MATLAB software.
