Rasool Kenarangui

Detection of Rotor Faults in Synchronous Generators

Synchronous generators are subject to a variety of failures which may occur in various parts of their structure. Furthermore, these faults may be categorized as partial failure or catastrophic faults. One may note that most partial faults can eventually result in a permanent lack of service. The present digest deals with a class of failures which may happen in the rotor of a turbo-generator. These faults include electrical failures in the Held n inding and mechanical faults in the form of dynamic eccentricity. Since the electromechanical conversion of energy is closely related to magnetic response of the machine any alteration of the excitation and geometry will result in detectable changes in stator quantities such as no-load voltage. The present digest is based on a detailed analysis of the electromagnetic response of a two pole turbo generator under various types of rotor faults. In the first step existence of detectable time-domain signatures have been investigated. Next, uniqueness of these signatures is studied. In the last part, a systematic method for just-in-time detection and classification of various rotor faults has been developed. Finite element analysis has been used for this study.

Energy management for motors, systems, and electrical equipment

Energy management embodies engineering, design, applications, operation, and maintenance of electrical power systems to provide optimal use of the electrical energy. The key element of the energy management process is the identification and analysis of energy conservation opportunities (ECOs). This paper presents a brief summary of Chapter 5 of the IEEE Std 739-1995, where the standard discusses the energy management and energy conservation for motors, systems, and electrical equipment.

Luminescence of La 0.2 Y 1.8 O 3 nanostructured scintillators

For the first time, transparent La0.2Y1.8O3 nanostructured polycrystalline scintillators were fabricated by sintering nanoparticle powders at high temperatures and their scintillation properties are reported. La0.2Y1.8O3 is a host material that has never been investigated as scintillators for radiation detection. Our observations found that La0.2Y1.8O3 has an intense scintillation luminescence, a detection efficiency higher than that of YAG:Ce and a comparable energy resolution to NaI and CsI scintillators. In addition, La0.2Y1.8O3 is stable and has luminescence decay lifetime in the picosecond range which is favorable for radiation detection. The luminescence of La0.2Y1.8O3 has a large Stokes-shift and a large emission bandwidth, and the luminescence is highly temperature dependent. Different from most doped scintillators, the luminescence of La0.2Y1.8O3 is most likely from the self-trapped excitons. The discovery of La0.2Y1.8O3 scintillators opens a new door for the research of new materials for radiation detection.

Luminescence of La0.2Y1.8O3 nanostructured scintillators

For the first time, transparent La0.2Y1.8O3 nanostructured polycrystalline scintillators were fabricated by sintering nanoparticle powders at high temperatures and their scintillation properties are reported. La0.2Y1.8O3 is a host material that has never been investigated as scintillators for radiation detection. Our observations found that La0.2Y1.8O3 has an intense scintillation luminescence, a detection efficiency higher than that of YAG:Ce and a comparable energy resolution to NaI and CsI scintillators. In addition, La0.2Y1.8O3 is stable and has luminescence decay lifetime in the picosecond range which is favorable for radiation detection. The luminescence of La0.2Y1.8O3 has a large Stokes-shift and a large emission bandwidth, and the luminescence is highly temperature dependent. Different from most doped scintillators, the luminescence of La0.2Y1.8O3 is most likely from the self-trapped excitons. The discovery of La0.2Y1.8O3 scintillators opens a new door for the research of new materials for radiation detection.

Frequency Domain Methods for Detection of Rotor Faults in Synchronous Machines under No-Load Condition

Reliable and efficient generation of electricity is of paramount importance in an advanced electric power network. Whether in large synchronous generators that are installed in power plants or for distributed generators in wind farms, survivable performance of these electric machines plays a vital role in accomplishing this goal. The worldwide economical impact of achieving a reliable generation is immeasurable. As a result real time monitoring and just-in-time maintenance of synchronous generators deserves due attention. The present paper deals with this outstanding issue. Synchronous generators are subject to a variety of failures which may occur in various parts of their structure. The present paper deals with a class of failures which may happen in the rotor of a turbo-generator. Since the electromechanical conversion of energy is closely related to magnetic response of the machine any alteration of the excitation and geometry will result in detectable changes in stator quantities such as voltage and current. The present paper is based on a detailed finite element analysis (FEA) of the electromagnetic response of a two pole synchronous generator under various types of rotor faults. In the first step existence of detectable time-domain signatures have been investigated. Next, uniqueness of these signatures is studied. Accordingly, a systematic method for just-in-time detection and classification of various rotor faults has been developed.

Control Strategy for Load Sharing in Distributed Generation System in Parallel Operation

Abstract- This paper presents a control strategy for parallel operation of distributed generation system. The proposed control technique, is based on the modified droop control method without any interconnection. This method is usually applied to achieve proper active and reactive power sharing when communication between each of distributed generation is difficult due to its physical location. In this paper investigate active and reactive power sharing of parallel operation. The power sharing is achieved by adjusting the frequency and voltage amplitude of each unit. Each unit has its own controller then the total active and reactive power can be shared by each unit in proportion with their rated power. Simulation results show that the proposed method is effective in displaying a reliable and control performance. A system consisting of three distributed generation represented by inverters has been simulated in MATLAB/Simulink. Different cases of power rating and load condition are verified by the simulation results.

Benefits of upgrading protection schemes for hydroelectric power plants

The role played by various energy sources has undergone a sweeping change during the post-deregulation era in the power industry. In the wake of this transformation, hydroelectric power plants, primarily employed as peaking units, assume great opportunities in participating on load balancing and other ancillary services market. A comprehensive protection plan for hydroelectric power plants would be of great importance to improve their availability and security. This paper focuses on the benefits of elevating the existing hydrounit protection to microprocessor based protection schemes. Effects of this protection upgrade on the system reliability, availability and power market are discussed. These discussions are substantiated by an illustrative study carried out for a hydro-electric power plant in Central Texas. The paper concludes with generic recommendations on upgrade procedure for hydroelectric power plants

Luminescence of La_02Y_18O_3 nanostructured scintillators

For the first time, transparent La0.2Y1.8O3 nanostructured polycrystalline scintillators were fabricated by sintering nanoparticle powders at high temperatures and their scintillation properties are reported. La0.2Y1.8O3 is a host material that has never been investigated as scintillators for radiation detection. Our observations found that La0.2Y1.8O3 has an intense scintillation luminescence, a detection efficiency higher than that of YAG:Ce and a comparable energy resolution to NaI and CsI scintillators. In addition, La0.2Y1.8O3 is stable and has luminescence decay lifetime in the picosecond range which is favorable for radiation detection. The luminescence of La0.2Y1.8O3 has a large Stokes-shift and a large emission bandwidth, and the luminescence is highly temperature dependent. Different from most doped scintillators, the luminescence of La0.2Y1.8O3 is most likely from the self-trapped excitons. The discovery of La0.2Y1.8O3 scintillators opens a new door for the research of new materials for radiation detection.