Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Oleksandr MIROSHNYK"

The incentive scheme for maintaining or improving power supply quality DOI:10.15199/48.2019.05.20

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Modern power systems must supply consumers with the high-quality power with the certain continuity level (that means the term «reliability of power system's work»). There are various aspects of realization of this process (objective and subjective aspects; material, technical, organizational aspects and others). All of them must be analyzed by staff of power distribution companies for improvement of service quality and ways of power supply process perfection must be defined. Employees should use precise and clear algorithm of actions for success of the task performance. They must understand consequences and an ultimate goal. An incentive scheme must be in the power distribution companies for conscientious work of employees. The implantation of an incentive scheme for maintaining or improving general continuity levels was one of recommendations the Council of European Electricity Regulators (CEER) that were submitted in 5-th benchmarking report [1] in 2011 year. The regulation of the service quality in European countries is considered in 6-th CEER benchmarking report on the quality of electricity and gas supply [2]. The systems of regulation are created on the basis of: Continuity measurement is a prerequisite for setting standards and reward/penalty regimes; Maintenance and improvement of general continuity levels as a result of the investment decisions of network operators with implementing reward/penalty for the achieved quality levels; Minimum standards for quality levels will guarantee that consumer will be compensated if the standard is not met by the network operator. The review of use of incentives systems for the distributive companies in the European countries on the basis of key reliability metrics is considered in [2]. Key reliability metrics are indicated in IEEE Std. 1366-1998 Trial-Use Guide for Electric Power Distribution Reliability Indices [3]. These must definitely be interpreted and used as re[...]

The influence of the specifications of the elements of range of exciters voltage inverters on their spectral characteristics DOI:10.15199/48.2019.05.21

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The trend of wide implementation of voltage inverters in various industries is forcing to focus on issues related to electromagnetic compatibility. For example, modern power inverters keys, especially MOSFET and IGВТ with have very high switching speed, become sources of electromagnetic interference. The range of generated interference extends from the carrier frequency of the inverter (several hundreds of KHz) to radio frequency (tens of MHz). Low-frequency interferences up to 2 kHz penetrate into the supply network, high-frequency (> 10 kHz) components create a powerful radio interference [1-4]. It is known that the PLL is generally described by nonlinear differential equations [5]. The non-linear nature of the circuit, which determined by the existence of semiconductor elements (diodes, transistors, thyristors, etc.) which are part of the inverter structure chart, is the reason for generating the higher harmonics. Therefore, we carry out a research on the effects of the non-linear nature of the drivers elements, namely the research of influence of range exciters and inventers systems of phase timing on the spectral characteristics. One of the major problems which must be solved during design and production of the voltage inverter is to eliminate adverse effect of the exciter on the technical characteristics (TС) of the inverter, in particular on electromagnetic compatibility. Thereby, the development of recommendations on the choice the optimal parameter values of the phase-locked loop (PLL) of frequency synthesizer on the basis of accurate numerical analysis occurring therein is very important. For the calculated ratios we use the method of functional expansions of Voltaire, which currently is one of the most convenient and accurate methods for analyzing non-linear dynamic systems [6, 7]. Experiment As the main circuit of direct digital synthesizers (DDS) of range exciters (which basing on the analys[...]

Reducing the dissymmetry of load currents in electrical networks 0,4/0,23 kV using artificial neural networks DOI:10.15199/48.2019.11.56

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The problem of the quality of electric energy plays a prominent role in development strategies of virtually every state. In European countries, it is believed that if the electricity losses exceed 7 - 9%, then such a transfer of electric energy is inefficient. Therefore, a need has emerged to develop new methods and measures of reducing the losses and improving the indicators of electric energy quality. Numerous studies on the analysis of voltage up to 0,4/0,23 kV in rural networks operating modes [1 - 3] showed that current dissymmetry is due to of municipal and household workload, most of which consists of casual switching, single-phase power-consuming equipment that is non-uniformly distributed over the phases. Knowledge of current values of asymmetry in a network allows specifying its additional power losses comparing to the symmetrical mode and the possibility of applying measures to reduce the losses [2]. The changing load of single-phase residential consumers of electricity is erratic and it is very difficult to predetermine its value at any given time. Boundaries of load change can only be established with a certain probability [4, 5, 6]. Technical and economic characteristics of the network performance deteriorate sharply in single-ended mode: energy losses increase and the voltage deviation from the nominal [7, 8]. Lifetime of asynchronous motors attached to a network also declines sharply. Furthermore, there are a number of adverse electromagnetic effects, both in the network and in the load. Therefore, losses of active energy, resulting in non-uniformity of phase load lines 0,4/0,23 kV and consumer transformers 6-10/0.4 kV, may increase by more than a third compared with the losses that would have occurred with a uniform load [3]. Analyzing two types of asymmetry, systematic, which is caused by a constant uneven phase load over time, and probable, which is determined by randomly varying loads in time, one fir[...]

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