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The paper deals with the behavior of a medium / low voltage transformer (MV/LV), for a non-sinusoidal consumer placed in the transformer's secondary winding. The analysis is performed using the Discrete Wavelet Transform (DWT). The monitoring is realized with two data acquisition systems, briefly described in the paper. Problems associated to the conducted and radiated emissions are addressed and...
The paper deals with the design of an electric locomotive drive system used in electric railway transportation. The drive system consists of an induction motor and a voltage source inverter. A dedicated induction motor design algorithm is developed, in order to improve the motor efficiency. The design of the induction motor was realized with MathCAD and validated with Matlab Simulink. In the second...
The capabilities related to active filtering of the Stationary Wavelet Transform — SWT were evaluated considering 3 Daubechy wavelet mothers. Firstly a study on errors was performed on synthetic waveforms. The waveforms were obtained from sinusoids polluted by single harmonics with orders from the range 3…40 and magnitudes, respectively phase differences varied in a systematic manner. The differences...
The design process of a rectangular waveguide pyramidal horn antenna is carried out. A mathematical design algorithm is developed and implemented in Matlab. The antenna model is built afterwards, accounting for the same computed parameters, with two different dedicated antenna design and simulation software packages: CST Microwave Studio and ANSYS HFSS. Both are based on the Finite Element Method...
Special preprocessing techniques for denoising quasi-stationary signals (SN) acquired from the secondary winding of the excitation transformer in a power plant are addressed. Sequences of 30 periods were analyzed. SN were polluted by white Gaussian noise and “average” signals (AS) of one period length were deduced. Because vectors of samples were handled, corrective measures (CM) were applied firstly...
A complex data acquisition system used in the monitoring and diagnosis of an entire large power group delivering electric power in a power system is presented. The tests are performed with three independent synchronized data acquisition systems able to acquire up to 24 electrical quantities. The hardware and software solutions are described. Considerations on the preprocessing of data and preliminary...
The results of the measurements concerning the electric quantities from an auxiliary generator, a three-phase rectifier controlled by thyristors, and a main generator from a power group, performed using an integrated measuring system are presented. The modality to determine the power quality parameters is detailed. The analysis allows the detection of possible undesired distorting regimes, with serious...
The paper deals with the behavior of a medium voltage/low voltage transformer (MV/LV), used to power the excitation circuit of a power group. The transformer's load is nonlinear, therefore inducing strong non-sinusoidal regimes in the primary and the secondary windings of the transformer. Non-sinusoidal regimes are due a thyristor rectifier used to power excitation. Two distinct situations are analyzed,...
The paper deals with the components design and the simulation of a photovoltaic power generation system using MATLAB and Simulink software. The power plant is composed of photovoltaic panels connected in series and parallel strings, a DC-DC boost converter and a three-phase inverter which connects to a 0.4 kV three-phase low voltage grid and a 20 kV medium voltage grid by means of a step-up transformer...
The paper focuses on the joint analysis (using Wavelet Packet Transform (WPT)/Discrete Wavelet Transform (DWT) and respectively Fast Fourier Transform (FFT)) of voltages and currents acquired from a generator operating in the Power Plant Turceni, Romania, as a major stage in designing the components of an active power filter (APF). When fast methods, providing accurate results are used, fundamental...
The paper deals with the problems introduced by a fully controller rectifier with thyristors (FCTR), used in the supplying circuit of a power plant's excitation winding. The rectifier is supplied from the secondary winding of a 3.256 MVA, 24 / 0.65 kV power transformer (PT), in a schema modified with respect to the excitation supplying from an auxiliary generator. The use of PT supplied from the main...
The paper presents a method for monitoring and diagnosis of the effects yielded by the non-sinusoidal regime over the voltage transformers operating in a power group. The analyzed schematic structure is presented along with all its components. Information on the designing, construction and implementation of a data acquisition system (DAS) are presented, along with the interface for data visualization...
A control strategy for positioning systems used in hail suppression is presented in this paper. The proposed position control solution is designed to obtain a precise control of the launch pad position over the azimuth and elevation, resulting in controlling a system with two degrees of freedom. The proposed strategy has been simulated starting from a permanent magnet synchronous motor that was modeled...
The paper deals with problems related to non-sinusoidal regimes introduced in the supplying network by a laptop and respectively by a set of laptops connected in various configurations. The three-phase voltage(s) and current(s) were acquired with an original data acquisition system with a sampling frequency of 19,200 Hz. Harmonic decompositions up to an order of 192 (corresponding to a frequency of...
The paper analyzes the behavior of a three-phase consumer, consisting of several personal computers connected to a transformer's secondary phases. The modalities of monitoring and recording of electrical quantities are presented in this work. The structure of the consumer is described. The recorded waveforms are analyzed. The Fast Fourier Transform (FFT) analysis allowed for the decomposition of the...
The paper deals with the single-phase active filtering used for reducing the harmonic level and electromagnetic interference and to get compliance with the power quality standards. The active filtering in case of a single-phase rectifier is based on a single-phase active filter and a complete current control system that uses pulse-width modulation (PWM) techniques. The power quality and the existing...
The paper deals with a comparison between the energy received by solar panels in two different facilities. The study is based on the design of two positioning systems and the amount of energy received by them. The manufacturing of the mobile support is treated first, then the design of the stationary support is presented. At the next stage, one realized the design of the control circuit, managing...
The paper deals with techniques to accelerate the DWT power quality analysis. Firstly a non-spline interpolation schematic is proposed for the evaluation of the first components near the right border of the signal. Comparisons are made between power quality indices, shape of details waveforms and runtimes, considering 3 cases. The first 2 cases correspond to data acquired on stand and correspond to...
This paper presents measurements comprising both power quality and EMC fields for a static excitation system composed of a transformer and controlled rectifier bridge in a power system generator group. The replacement of the old auxiliary excitation generator eliminates the disadvantage of using electrical machines with the mass in motion inertia and wear over time, but with the price of facing two...
The paper deals with Power Quality (PQ) and Electromagnetic Compatibility (EMC) related problems, occurred during the operation of a driving system with induction motor and AC-DC-AC converter. The induction motor's driving system is presented, along with its characteristic features. An analysis is made with respect to the power quality indices related to the voltage and current absorbed from the power...
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