In this paper, the possibilities of rolling bearing diagnostics, according to the PN and ISO standards, utilising the dimensionless discriminants of vibroacoustic processes, CPB frequency analysis and envelope detection methods are presented. The test bench, the measuring system, as well as the obtained results are described in detail. The authors’ own algorithm for the course of action during the process of detecting damage torolling bearings, involving the multi-criterion diagnostic utilising the afore methods is also described.

This article presents the results of the analysis of a six-electrode pulse current electric arc furnace (EAF). The characteristics of a power supply system for an EAF are presented for symmetrical states and the most probable asymmetrical states.

This paper concerns a salient pole synchronous generator with damping bars on the rotor, and presents a comparison of the distribution of self and mutual inductances in the stator natural reference frame abc for a linear and a nonlinear circuital model, as well as in the rotor reference frame dq0. Moreover, this paper shows a proposed method of modeling the damping circuits on the rotor of a salient pole synchronous generator. An experimental verification of the registered induced voltage in the damping bars on the rotor is presented.

The efficiency of three-phase voltage source inverters depends mainly on power losses that occur in semi-conductor elements. Total losses in these elements are a sum of conduction losses and switching losses. The switching losses are dependent on the supply voltage, load current, operating frequency and on the dynamic parameters of the switching elements; these losses can be limited with the use of soft switching methods. This paper discusses the switching loss dependence on the above mentioned factors. An analysis was carried out on power losses in voltage source inverters which generate the output voltage in the form of a rectangular wave and losses in these inverters operating with pulse width modulation. A comparison of switching losses was performed for two voltage source inverters with different nominal power ratings.

The design of a ferrite magnet generator with trapezoidal shaped permanent magnets and coils for a wind turbine is studied. Based on the 3-D finite element analysis (FEA), the electromagnetic performances of the two generator prototypes and a simple design modification for one of the axial-flux generator prototypes are analyzed. The best generator is chosen from a range of designs, where the goal is to increase the voltage generated by the 8/8 pole and a single-phase slotless machine. Experimental results from a small size prototype machine validate the 3-D FEA models presented, and hence give confidence in their use for design.

The main aim of this paper is to identify relationships for direct determination in the time domain of periodic steady-state solutions for differential equations. A new discrete operator of differentiating has been defined. As a result, a set of algebraic equations has been written. Based on this, an algorithm for nonlinear differential equations has been proposed. Numerical tests have been carried out both for a new discrete operator and for steady-state analysis in a simple electromechanical converter.

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.

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.

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.

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.

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.

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.

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.

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.

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 bestn ant algorithms that are already known.

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.