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This paper proposes an accurate and computationally efficient implementation of the IEEE Std. 1459-2010 for power measurements. An implementation is based on digital resonators embedded in a feedback loop. In the first algorithm stage, the unknown signal harmonic parameters are estimated. By this, the voltage and current signals are processed independently of each other. In the second algorithm stage, the unknown power components are estimated (calculated) based on estimated spectra. To demonstrate the performance of the developed algorithm, computer-simulated data and laboratory testing records are processed. Simple LabView implementation, based on the point-by-point processing feature, demonstrates techniques modest computation requirements and confirms that the proposed algorithm is suitable for real-time applications.

Hardware-in-the-loop (HIL) simulation is a technique that is being used increasingly in the development and test of complex systems. Real-world testing of an intricate system in a field-like power plant can be challenging, time-consuming, expensive, and hazardous. HIL emulators allow engineers to test devices thoroughly and efficiently in a virtual environment with high reliability and minimum risk of defect. In this paper, the complete electric power system (including generator, turbine-governor, excitation system, transmission lines, transformer, external grid and related loads) is implemented in a MATLAB/Simulink environment. Different virtual instrument pages are modeled in the graphical programming language of LabVIEW which enable fast and reliable measurement functions such as data acquisition, archiving, real-time graphical display and processing. The interaction between MATLAB and LabVIEW is accomplished by generating a Pharlap ETS Targets *.dll file which enables the two software to exchange real-time data. Also, a real 1518-kW excitation system is considered as a test case for the introduced HIL system. This equipment is connected to LabVIEW software through a National Instrument PXI technology. Different scenarios (electrical frequency/active power change, voltage step response, etc.) are simulated in the designed power system emulator (PSE). The validity of the implemented model for the excitation system is verified by finding good matching between MATLAB and HIL simulation results. [ABSTRACT FROM AUTHOR]

Higher order cumulant (HOC) is a new theory and method of modern signal analysis. Empirical mode decomposition (EMD) is a new time-frequency analysis method for analysis of non-stationary and nonlinear processes. This paper discusses the characteristics of both HOC and EMD, investigates their related technology and advantage in the process of dealing with nonlinear coupling characteristics of random and non-stationary signals. Then through combining with the merits of HOC and EMD, it proposes a new method for multi-damage feature extraction and fault diagnosis of gear systems. For restraining system noise and extracting the fault features of signals, the acquired signal is decomposed into a three-layer signal which has different frequency bands, and then every layer is given to a HOC analysis. Six kinds of signal are analyzed including signal without fault, signal with tooth root short crack, signal with tooth root long crack, signal with pitch circle short crack, signal with pitch circle long crack and signal with tooth wear, which were acquired at four different speeds: 300 r/min, 900 r/min, 1200 r/min and 1500 r/min. The results demonstrate that this method not only can be used to identify various faults (including multi-fault) in the low-speed and high-speed running conditions, but can also be used to identify the damage level of some faults. On this basis, combining the advantages of MATLAB and Visual C++ (VC++), a virtual instrument (VI) system of gear damage detection and diagnosis is developed through a mixed programming method. The interface is designed with VC++, the calculation of test data, signal processing and graphical display are completed by MATLAB. Using COM module technology, it calls the *.m file conversion program in VC++. A different kind and multifunctional gear fault diagnosis software system is successfully empoldered, which possesses some functions, including the introduction of gear vibration signals, signal processing, feature extraction, graphics display, fault detection and diagnosis. The system can be used to detect damage and diagnose faults in gear systems as proven by the results of the validation testing. [ABSTRACT FROM PUBLISHER]

The windings of power synchronous machines are often parallel connected to obtain the desired machine voltage and current ratings. Ideally, the split-phase currents are equal in symmetrical windings, so as to avoid parasitic circulation of current in the parallel branches. However, the symmetry is broken in case of rotor eccentricity, and the split-phase currents become unbalanced. Part I of this paper analyzed the theoretical behavior of the unbalanced currents by using symmetrical components. A new fault diagnosis method was shown, based on a combined space-vector/fast Fourier transformation (FFT) analysis of signatures in the split-phase currents. This Part II applies the split-phase current signature analysis to a laboratory 17-kVA synchronous generator with artificial faults. Method performances have been evaluated with mixed static/dynamic type fault, in no-load and loaded conditions. The experiments are matched with time-stepping finite-element simulations, which help explain the effect of saturation and load on the diagnosis accuracy. The feasibility of installation of current probes in practical machines is also discussed. [ABSTRACT FROM PUBLISHER]

A gear transmission system is a complex non-stationary and nonlinear time-varying coupling system. When faults occur on gear system, it is difficult to extract the fault feature. This paper researches the threshold principle in the process of using the wavelet transform to de-noise the system, and combines EMD (empirical mode decomposition) with wavelet threshold de-noising to solve the problem. The wavelet threshold de-noising is acts on the high-frequency IMF (Intrinsic Mode Function) component of the signal, and does overcome the defect by simply highlighting the fault feature. On this basis, the pre-processed signal is analyzed by the method of time-frequency analysis to extract the feature of the signal. The result shows that the SNR (signal-noise ratio) of the signal was largely improved, and the fault feature of the signal can therefore be effectively extracted. Combined with time-frequency analyses in the different running conditions (300 rpm, 900 rpm), various faults such as tooth root crack, tooth wear and multi-fault can be identified effectively. Based on this theory and combining the merits of MATLAB and VC++, a multi-functional gear fault diagnosis software system is successfully exploited. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the performance results of a Virtual Instrument (VI) based in Case-Based Reasoning (CBR), conceived to online monitor the power-quality. The PC-based instrument receives data through a DAQ board and a differential probe, while maintaining economy by eliminating the extra network construction and hardware. Being flexible, presents an user-friendly interface and a large data storage capacity, since it uses the hard disk. The computational guts of the instrument are based in third and fourth-order statistics (along with the variance), which enhance detection capability and reject noise influence. A time-domain sliding window sweeps the register under test and offers a time-variation pattern which reflects the deviation of the statistical estimator with respect to the steady state. This three-valued time-series comprises variance, skewness and kurtosis evolution, and constitutes a triple input to the innovative CBR module, which in turn is capable of distinguishing electrical anomalies among five categories (the sixth is reserved to the healthy signal): non-50Hz, 50-Hz-asymmetrical, 50-symmetrical non-sinusoidal, swell and sag. Online surveillance tests developed over the local electrical network show acceptable accuracy (96%). [Copyright &y& Elsevier]

In this paper, a synthetic vector network analyzing measurement system is presented. The system is based on a hardware setup, including a signal generator and a vector signal analyzer, with the vector network analyzing functionality implemented in the software. The measurements of the proposed system demonstrated comparable performance in terms of accuracy and speed compared with a modern traditional vector network analyzer, but it is more flexible due to its inherent software implementation. The proposed system's ability to measure nonlinear phenomena is addressed and discussed, and some preliminary results are given. [ABSTRACT FROM AUTHOR]

This paper proposes an accurate and computationally efficient implementation of the IEEE Standard 1459-2000 for power measurements. The algorithm has two stages. In the first algorithm stage, the voltage and current signals are processed in parallel, and their spectrums are estimated independently of each other. Signal harmonics are estimated in a wide range of frequency using an efficient algorithm with reduced complexity. The algorithm is based on a recently introduced common structure for recursive discrete transforms and consists of digital resonators embedded in a common negative feedback loop. In the second algorithm stage, the unknown power components and other power quality indices are calculated according to definitions in the IEEE Standard 1459-2000. To demonstrate the efficiency of the proposed algorithm, the results of computer simulations and laboratory testing are presented. The laboratory results show accurate input power component estimates for a nonlinear load with rapid input current amplitude changes. In addition, a simple LabView implementation, based on the point-by-point processing feature, demonstrates the technique's modest computation requirements and confirms that the proposed algorithm is suitable for real-time annlications. [ABSTRACT FROM AUTHOR]

A multimission microsatellite is currently being built by the Satellite Engineering Centre, Nanyang Technological University, Singapore, in collaboration with the DSO National Laboratories, Singapore. Among the various subsystems, the power supply is one of the most critical parts of the satellite. Its primary and secondary power sources, i.e., the solar array and the battery, and the various power converters are responsible for supplying power with well-regulated voltages to the satellite throughout the whole mission. To test and evaluate the performance of the system, with the satellite operating in different simulated space scenarios, a virtual-instrument-based test and measurement system has been developed. Experimental results that were obtained from the setup have shown that the system is a valuable tool that provides data that are difficult to obtain from analysis and software simulation. [ABSTRACT FROM AUTHOR]

Traditional methods to measure power system harmonics employ the power harmonic analyzer or a software package, such as Matlab or others, but they do have certain limitations in the graphical programming environment, applications for remote monitoring and control performance. This paper presents a virtual instrument (VI) that can carry out power system harmonic measurement based on fast Fourier transform (FFT) in remote surveillance capability via the Internet. The strategies and guidelines are also developed to enhance teaching and/or learning the basics of operating Internet-based systems. Critical issues pertaining to engineering education, such as design of course, expected learning outcomes, assessment of student performance, and course evaluation are discussed in detail. [ABSTRACT FROM AUTHOR]

The objective of this paper is the design and development of the data-acquisition and storage parts of a measurement system that will be used for condition monitoring (CM) of power transformers. The data captured from the sensors and stored in the database will be used for the prediction of the power transformer's behavior. These data-storage and data-acquisition parts have been developed using data-warehouse (DW) techniques and virtual instruments (VIs). This paper makes a brief introduction to the whole CM system and describes in depth the data-acquisition and data-store subsystems. Then, the fundamental considerations about the installation and maintenance are outlined. Next, the results of the project are described, and other existing commercial CM systems are briefly discussed. Finally, the fundamental conclusions, obtained from the installation of this CM system, are shown. The CM system is currently installed and working properly in four electric power transformers. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach to the virtual instrument (VI) time analysis. The main assumptions and issues are presented. A methodology of the VI time parameter assessment and measurement is proposed. The verification of the methodology is discussed. The premises for future research are outlined. [ABSTRACT FROM AUTHOR]

This article introduced a DSP controlled gas shielded welding machine. Based on it, a welding power source system study platform by virtual instrument LabView technology was established. By means of digital signals processing and flexible program, it can realize suitable characteristics of welding machine, line compensation, welding voltage and current feedback, wire-feed driving and so on, which can greatly enhance the stability and reliability of welding machine. The welding current and welding voltage signals in real time are collected and displayed, and demarcate signals are added to represent different welding period. Statistical analyzing method is used to process welding parameters in probability density distributing diagrams. The experimentations prove that this system works stably and can satisfy the system study requirements. [ABSTRACT FROM AUTHOR]

A novel fiber Bragg grating (FBG) sensor system for static and dynamic measurements with a wavelength-swept fiber laser is proposed and demonstrated. In this system, both static and dynamic perturbation of each FBG in the sensor arrays can be interrogated simultaneously. The experiments demonstrated the strain resolutions of ∼1 με and 3.4 nε/√Hz at 500 Hz for static and dynamic measurements, respectively. [ABSTRACT FROM PUBLISHER]