Wyniki 1-4 spośród 4 dla zapytania: authorDesc:"Mohammad-Reza MOSAVI"

Error Reduction for GPS Accurate Timing in Power Systems using Kalman Filters and Neural Networks

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The Global Positioning System (GPS) based time reference provides inexpensive but highly-accurate timing and synchronization capability and meets requirements in power system fault location, monitoring, and control. Precision satellite clocks and time measurements are the keys to the accuracy of GPS. A stand-alone civilian user enjoys an accuracy of 25 meters and 200 nanoseconds. Five methods, including two methods using Kalman Filter (KF), Recurrent Neural Network (RNN), Pi-Sigma Neural Network (PSNN) and Sigma-Pi Neural Network (SPNN), are proposed for error reduction of GPS receivers timing data. We use actual data to evaluate the performance of the proposed methods. An experimental test setup is designed and implemented for this purpose. Results using the five methods are discussed. The experimental results obtained from a Coarse Acquisition (C/A)-code single-frequency GPS receiver strongly support the potential of the method using PSNN to give high accurate timing. The GPS timing RMS error reduces to less than 38 nanoseconds. Streszczenie. Opisano zastosowanie system pozycjonowania GPS lokalizacji uszkodzeń i monitorowania sieci przesyłowej. System cywilny GPS oferuje dokładność rzędu 25 m i 200 nanosekund. Opracowano szereg metod poprawy dokładności, wykorzystujących filtry Kalmana i sieci neuronowe. Zredukowano błąd taktowania do około czterdziestu nanosekund. (Metody zmniejszenia błędów systemu GPS przy wykorzystaniu filtrów Kalmana i sieci neuronowych) Keywords: Error Reduction, GPS Receivers, Timing Data, Power Systems, Kalman Filter, Recurrent Neural Network, Pi-Sigma Neural Network, Sigma-Pi Neural Network Słowa kluczowe: GPS, filtry Kalmana, sieci neuronowe. NOMENCLATURE RMS Root Mean Square SA Selective Availability KF Kalman Filter NN Neural Network PMU Phasor Measuring Unit PPS Pulse Per Second UTC Universal Time Coordinated MSE Mean Squared Error AR Auto-Regressive UTOD Universal Time of Day RNN Recurrent Neural N[...]

Design of Efficient Adaptive Neuro-Fuzzy Controller Based on Supervisory Learning Capable for Speed and Torque Control of BLDC Motor

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Brushless DC (BLDC) motors have been widely used in many field of drives for their high power/weight, high torque, high efficiency, long operating life, noiseless operation, high speed ranges and ease of control. In this paper, a Neuro-Fuzzy Controller (NFC) based on supervisory learning is presented for the speed and torque control of BLDC motors to enhance high control performance of the drive under transient and steady state conditions. This designed controller is combination of Neural Networks (NNs) and Fuzzy Logic (FL), therefore has parallel processing and learning abilities of NNs and inference capacity of FL. For improvement the performance of leaning algorithm and thereupon increase efficiency of drive, instead of usual Error Back Propagation (EBP) learning technique, a fuzzy based supervisory learning algorithm is employed. The proposed controller has simple structure and also due to its modest fuzzy rule in rule-base is relatively easy for implementation. This controller has high accuracy, suitable performance, high robustness and high tracking efficiency. In order to demonstrate the NFC ability to tracking reference speed and torque and also test of robustness and rejection ability of controller against undesired disturbances or suddenly changes in speed and torque, these designs are simulated with MATLAB/SIMULINK. In some cases, results are compared with that of a conventional PID controller and other designs. Streszczenie. W artykule zaprezentowane układ sterowania bezszczotkowym silnikiem DC z wykorzystaniem sterownika Neuro-Fuzzy. Dla poprawienia efektywności uczenia sieci zamiast wstecznej propagacji błędu zaproponowano algorytm wykorzystujący logikę rozmytą. Sterownik okazał się być dokładny, odporny i o dużej efektywności śledzenia zmian. Porównano możliwości kontrolera z konwencjonalnym sterownikiem PID. (Projekt skutecznego sterownika silnika bezszczotkowego DC z wykorzystaniem sieci neuronowych i logiki rozmytej) Keywor[...]

Fault Location Techniques in Power System based on Traveling Wave using Wavelet Analysis and GPS Timing

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In this paper two approaches are proposed based on Discrete Wavelet Transform (DWT) and traveling wave to locate the fault of the three phase transmission line. The exact fault position is determined according to the instances in time when the fault waves arrive at each locator location and wave speed calculated on the basis of the proposed algorithms. To achieve actual data, synchronized sampling is needed which can be made possible by precise time receivers based on Global Positioning System (GPS) time reference. All the possible fault types are generated using the ATP-EMTP and results using the two methods are discussed. Extensive simulation studies indicate that the proposed approaches are reliable for rapid and correct identification of various fault cases. Streszczenie. Przedstawiono system do badania trójfazowej lini transmisyjnej. Metoda wykorzystuje falę wędrująca i dyskretną transformatę falkową oraz system GPS. Badania wykazały przydatność systemu do lokalizacji uszkodzeń sieci.(Technika lokalizacji uszkodzeń linii przesyłu energii wykorzystująca analize falkową i system GPS) Keywords: Power System, Fault Location, Traveling Wave, Wavelet Transform, GPS Timing. Słowa kluczowe: lokalizacja uszkodzę, sieć transmisyjna, transformata falkowa. Introduction Transmission line faults are the most common faults, triggered by falling trees across lines, lightning strikes or insulator strings to flash over. Economic and reliable operation of a power system requires fast fault location and fast fault clearing. Concepts of availability, efficiency and quality have an increasing importance nowadays due to the new marketing policies which can be directly interpreted as a cost reduction or a profit increasing. Conventional methods use measurements of voltage and current at the substations. Fundamental component during pre-fault and fault are used in these methods to estimate the apparent impedance viewed from the measurement point and th[...]

A PMU Placement Optimal Method in Power Systems using Modified ACO Algorithm and GPS Timing

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In this paper, optimal placement of Phasor Measurement Unit (PMU) using Global Positioning System (GPS) is discussed. Ant Colony Optimization (ACO) is used for this problem. Pheromone evaporation coefficient and the probability of moving from state x to state y by ant are introduced into the ACO. The modified algorithm exceeds the ACO in obtaining global optimal solution and convergence speed, when applied to optimizing the PMU placement problem. The fitness function includes observablity, redundancy and number of PMU. Eigenvector Method (EM) is used to calculate the weights of fitness function. The suggested optimization method is applied in 14-bus IEEE system and the simulation results show that the proposed method can find the optimal solution in an efficient manner. Streszczenie. W artykule analizowano optymalne usytuowanie jednostki PMU (phasor measurement unit) przy wykorzystaniu system GPS. Do rozwiązania problemu wykorzystano algorytm mrówkowy. (Optymalna metoda usytuowania jednostki PMU w systemie zasilania przy wykorzystaniu algorytmu ACO i systemu GPS) Keywords: Phasor Measurement Unit, Placement Optimization, Ant Colony Optimization, Analytical Hierarchy Process. Słowa kluczowe: jednostka PMU (phasor measurement unit), GPS. Introduction The Global Positioning System (GPS), which is a satellite based system, is the main synchronizing source that is used to provide a time reference on the communication networks, and its widespread availability makes it possible to obtain, at each point of the tested system, a clock signal that is synchronized with the one generated in other remote places. Currently, GPS is the only satellite system with sufficient availability and accuracy for most distributed monitoring and control applications in distribution systems. Synchronizing signals could also be broadcast from a terrestrial location, and, with respect to this, radio broadcasts are probably the least expensive [1]. The time refere[...]

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