Mahdi Karami

Determining optimal location of Static Var Compensator by means of genetic algorithm

The purpose of this paper is to study a practical and accurate heuristic method known as genetic algorithm (GA) which is used to find the optimal location of Static Var Compensator (SVC) and its appropriate size and setting. This method is employed to optimize the stability of power system by means of maximizing distance to collapse point. The continuation power flow (CPF) method is employed to determine the collapse point and critical area of power system. Moreover, the total real power loss of system is minimized by this algorithm. Modeling and simulation is performed on IEEE 14, 57 and 118 bus test system. The obtained result implements the effectiveness of this method to find the best location, appropriate size and setting of this element to the desired targets.

On basic definition of optimal allocation of FACTS devices in power system

This paper presents the importance of FACTS elements allocation to describe the effect of FACTS devices and placement of these devices in the electric power system. Optimal allocation and control of these devices will be very important for ISO or other power market regulators. The best location, appropriate size and setting of FACTS devices are important in the deregulated electricity markets. Two types of FACTS devices are considered in this study, which are Static var compensator (SVC) and thyristor controlled series compensator (TCSC). Modeling and simulation is performed on IEEE 14 bus test system and results will be presented. The proposed research is effective and helpful in the study of voltage stability with the consideration of the FACTS elements.

Static Eccentricity Fault Recognition in Three-Phase Line Start Permanent Magnet Synchronous Motor Using Finite Element Method

This paper is dedicated to investigating static eccentricity in a three-phase LSPMSM. The modeling of LSPMSM with static eccentricity between stator and rotor is developed using finite element method (FEM). The analytical expression for the permeance and flux components of nonuniform air-gap due to static eccentricity fault is discussed. Various indexes for static eccentricity detection using stator current signal of IM and permanent magnet synchronous motor (PMSM) are presented. Since LSPMSM is composed of a rotor which is a combination of these two motors, the ability of these features is evaluated for static eccentricity diagnosis in LSPMSM. The simulated stator current signal of LSPMSM in the presence of static eccentricity is analyzed in frequency domain using power spectral density (PSD). It is demonstrated that static eccentricity fault generates a series of low frequency harmonic components in the form of sidebands around the fundamental frequency. Moreover, the amplitudes of these components increase in proportion to the fault severity. According to the mentioned observations, an accurate frequency pattern is specified for static eccentricity detection in three-phase LSPMSM.

Performance analysis of line-start permanent magnet synchronous motor in presence of rotor fault

Electrical Motors are widely employed in both industrial and domestic fields. Line start-permanent magnet motor is one of the modern high efficiency motor introduced. During working of electrical motors, various faults, like stator faults, rotor faults, bearings faults, occur that lead to malfunction of the motor. Among these faults, rotor fault, broken bar, is important in the motors with squirrel cage rotor. This paper deal with the finite element method of the electromagnetic field associated with this motor to find the performance of it with presence of rotor faults.

Increase Performance of IPMSM by Combination of Maximum Torque per Ampere and Flux-Weakening Methods

Interior permanent magnet motor (IPMSM) was used as air conditioner compressor to reduce the power consumption and improve the performance of the system. Two control methods including maximum torque per ampere (MTPA) and flux-weakening methods were employed to increase the speed range of the air conditioner compressor. The present study adapted the flux weakening algorithm technique which can be used for constant torque and constant power regions. Results indicated that the operation speed range of the IPMSM may increase significantly by using the proposed flux weakening algorithm.

Broken rotor bar detection in LS-PMSMs based on statistical features analysis of start-up current envelope

Early detection of asymmetry in electrical motors is important because of their diversity of use in different fields. A proper fault detection scheme helps to stop propagation of the failure or limit its escalation to severe degrees and thus prevents unscheduled downtimes that cause loss of production and financial income. Line start-permanent magnet motor (LS-PMSM) is one of the modern high efficiency motor introduced to the market recently. A new method for the fault diagnosis of a broken rotor bar in line-start permanent magnet synchronous motor is presented in this paper. The method is based on the analysis of the transient stator current envelopes of LS-PMSM using statistical features in time domain analysis. Four different level of load were investigated in this study to indicate the effect of load in broken rotor bar detection. Hilbert Transform is used to extract the envelope of the current signal during the transient reign.

Broken rotor bar detection of induction machine using wavelet packet coefficient-related features

Fault diagnosis of induction machine can be achieved through wavelet packet analysis to acquire information about its stability and mutability. This paper presents an experimental evaluation of applying wavelet packet transform based on the sideband components, (1 ± 2ks)fs, for broken rotor fault detection in induction machines. The wavelet-based method decomposes stator current signal into effective wavelet coefficients. It is shown that the root mean square (RMS) value of wavelet packet coefficients in special frequency bands collectively establishes a feature index. Once the broken rotor bar occurs, this index value increases to distinguish healthy and faulty mode of induction motor as well as fault severity. Additionally, we investigate the left sideband around the fundamental frequency (50Hz), (1 - 2s)fs, which specifically represents the stator current spectrum of the machine when a rotor bar breakage takes place. An induction motor with one and two bar breakage at 35%, 50% and 80% of full load are investigated. The experimental tests indicate good reliability of different frequency resolution for same frequency component.

Diagnosis of static eccentricity fault in line start permanent magnet synchronous motor

In this paper, finite element method is employed for diagnosis of static eccentricity in line start permanent magnet synchronous motor. The motor is modeled with different degrees of eccentricity. Stator current spectrum of healthy and faulty motor are analyzed using power spectral density technique. Amplitudes of harmonic components around fundamental frequency in stator current spectrum are proposed for static eccentricity detection in this type of motor.

Wireless Sensors System for Broken Rotor bar Fault Monitoring using Wavelet Analysis

Accurate condition monitoring prevents unexpected failures in electrical systems including induction machines, and hence improves their performance significantly. To enhance the reliability of condition monitoring systems, wireless sensor systems are developed. In the recent years, researchers have placed considerable emphasis on developing cost-effective scheme using wireless sensor systems for fault diagnosis of equipments in industry. As broken rotor bar is one of the main causes of malfunction in electrical motors, this paper proposes a method for early detection of this failure in induction machines using wireless sensor system. In this respect, a test bed is developed where a sensor measures the motor current and then a microcontroller connected to this current sensor read and send the data to wireless sensor for remote real time data analysis. In the receiver unit, a Lab VIEW based program is developed to store data in a database and MATLAB is used for signal processing and fault.

Statistical features analysis of transient current signal for broken bars fault detection in LS-PMSMs

Electrical motors constitute critical elements in certain industrial facilities and domestic fields as a prime mover. In spite of its good trait, failures in electrical motor cannot be impeded because it is mainly working in the industrial field. LS-PMSM is a high efficiency motor introduced recently in industrial field. LS-PMSM is a hybrid motor, which its rotor is combination of squirrel-cage rotor and high energy permanent magnets to have high starting torque and high efficiency together. Similar to other types of electrical motors, various faults that lead to malfunction of the motor occur in LS-PMSM during its operation. In this context, investigates diagnostic techniques for LS-PMSM with special reference to rotor faults. Since LS-PMSM has squirrel cage rotor, among different faults may happen in it, broken bar is the most important one. This paper deal with the finite element method to investigation of broken rotor bar faults on LS-PMSM with statistical feature analysis in the time domain using transient current signal.