Abstract:The paper discusses the parametric identification of a system model for the charge output accelerometer based on the simultaneous approximation of amplitude and phase characteristics. The mathematical relationships refer to three models: the mechanical, electrical and complete models, are discussed in detail. The numerical calculations include the parametric identification of the system model for the PCB357B73 accelerometer and determination of the uncertainties associated with the parameters of this model.
Abstract:The maximum clique problem is a very well-known NP-complete problem and for such a problem, meta-heuristic algorithms have been developed which ant algorithms belongs to. There are many algorithms including ant algorithms that have been elaborated for this problem. In this paper, a new dynamic function of selecting with a new improvement procedure in order to get a larger size of clique for the ant algorithm is presented and this search for the maximum clique in graph is compared to the best ant algorithms that are already known.
Abstract:The optimization of the parameters of the electric furnace temperature control was considered. The optimization was executed using genetic algorithms. The model takes into account nonlinearity, which is connected with the penetration of heat. Also, it is connected with losses of heat due to convection and radiation. The genetic algorithm determines the selection of parameters of the mathematical model in which the system accurately reproduces the input action.
Abstract:Images and video are often coded using block-based discrete cosine transform (DCT) or discrete wavelet transform (DWT) which cause a great deal of visual distortions. In this paper, an extension of the intra-scale dependencies of wavelet coefficients is proposed to improve denoising performance. This method incorporates information on neighbouring wavelet coefficients that are inside of manually created clusters. Extensive experimental results are given to demonstrate the strength of the proposed method.
Abstract:The following paper presents possibilities for the application of selected time-frequency analysis methods in the fault detection of cage induction machines in transient states. The starting phase current of the machine was chosen as a diagnostic signal. Selected faults were eccentricities – static and dynamic. In order to increase the selectivity of the obtained signal transformations, a notch filter was used to remove the base harmonic of the phase current. Two approaches of fault detection were compared. In the first approach, the characteristic feature of fault was extracted using DWT analysis. Next, TMCSA methodology was applied in which characteristic harmonics related to faults were shown on a time-frequency plane. In this case, applied methods were a Gabor transformation, STFT, CWT and Wigner–Ville’s transformation. In the analysis, a phase current signal approximated by DWT was used. DWT approximation was applied to filter higher harmonics which improves the resolution of the obtained transformations.
Abstract:This article presents the idea of asynchronous motor’s non-stationary stator starting current, filtration methods, in the non-invasive diagnosis of the rotor cage. The mathematical description of the selected analysis forms is omitted in favor of an indication of the practical aspects of the method application and the obtaining of sample analysis results. The object of the study was the single cage induction motor with exchangeable rotors for different faults, machine’s load was a generator with field current control system, which was used to control the load torque.
Abstract:The generation of electrical energy in small power plants which use renewable energy sources is often implemented with the use of induction generators. This paper presents a proposal of an energy generation system which is constructed with the use of a three-phase self-excited squirrel-cage induction generator. The idea of this proposal consists of a control method of the generator rotor magnetic flux linkage via fully controlled power electronic switches. The energy produced by the induction generator is transferred to a DC link via an uncontrolled rectifier and a DC-DC chopper. The proposed solution allows us to generate energy with the use of a relatively simple and reliable electrical machine. Additional important advantages of this concept are a small number of controlled elements, and an easy control method.
Abstract:There are many types of control method for shunt active power filter (SAPF) investigated up until now. The authors describe complex methods of determining active filter reference currents or powers. This paper is dedicated to a simple, but universally used control algorithm based on the load equivalent conductance approach. This method allows for non-active current compensation, energy buffering, and energy redistribution among loads under compensation. It is also useful for voltage-source as current-source inverter based active filters, and for DC system as well as for AC single or three-phase filters.
Abstract:A matrix N×M multiphase converter is a simple structure incorporating N×M bi-directional switches, connecting N input phases to M output phases and able to convert input voltages into output voltages of any shape and frequency. However, commutation problems and complicated control algorithms keep it from being utilized on a large scale. This paper gives a solution to the control system of the multiphase matrix converters for power system application. The practical application of multiphase matrix converters (MC) in power systems involves the study of application requirements, possible converter topologies and the development of new, reliable control algorithms. The MC is working as a connection device between power systems or as an interconnection device within the power system. The proposed tasks performed by the MC in the power system are power flow control and power flow oscillation dumping. The device can be viewed as new FACTS device-series power system connector, based on straightforward energy conversion.
Abstract:This paper presents the process of the development of the real life laboratory model of the five node power system of closed loop structure. The model was built using ‘power’ scaling and taking into consideration the parameters of the 400 kV lines built in the Polish National Power system. After the three-year development of the model, the parameters of the elements of this model were gained or obtained using classic identification procedures. During this part of the research, some differences between the parameter values given by the manufacturers and those obtained through identification procedures were reported and analyzed. The Matlab/Simulink model of the laboratory setup was then built to emulate the system behavior during dynamic states. The comparison of the currents, voltages and generator speeds proved to be simple tasks since the shape of the short-circuit current waveforms, for example, depends not only on parameter values but also on the time of the fault occurrence with respect to system voltages. Thus, the time responses of the laboratory and Simulink models were compared to evaluate time constants of the post fault processes.