The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The self-starting of induction motors in electric networks auxiliaries of electric stations under different types of short-circuits was researched using the methods of mathematical experiments and digital models.
Transitional processes of switching-off high-voltage capacitor banks by circuit-breakers with pre-insertion resistors are considered in the paper. Capacitor banks switching-off process by circuit-breakers with PIR was studied from the point of view improving electromagnetic environment via reducing switching currents by pre-insertion resistors. It is shown in the paper that appropriate resistances...
Phase balancing can offer planning engineers a low-cost means of reducing operating costs, improving efficiency in electric power systems. In general, utilities make phase balancing based on peak load by thinking that is the worst case scenario, but every time is not the case. In this paper, time varying phase balancing algorithm is proposed to investigate the effect of hourly phase balancing for...
Since it was first proposed, the new method of power demand forecasting using a stochastic model has been greatly talked about in the scientific community and increasing number of practical applications are being developed, since it is a simple and effective approach to forecast power demand within a small time interval. However, the relevant literature still assumes that all statistic parameters...
In the paper the problem of improving of electric power systems analysis using macromodels of their elements formed as state space equations using "black box" approach and expert analysis is considered. The process of the macromodel creation was illustrated on the example of transmission line. The problem of further adaptation of macromodels of electric power system elements to modern software...
The paper presents a new method developed to estimate the level of standard of reliability index SAIDI expected in the future for new power network conditions determined for making changes to the network configuration (including changes in the functionality of the components of the network). This involved defining a set of split times that make up the long and very long unplanned outage electrical...
The paper presents the defined conception of the agent structure of the multi-agent system that performs the tasks of power system protection. The required input data sets and the input agents that provide observability of the power system were determined. The paper also proposes the agent input data acquisition ways that allow fast access to power system status information. The proposal of agents'...
This paper presents a method of modelling a vacuum circuit breaker and surge protection in the Matlab package. The simulations were carried out in the capacity circuit with varistor surge protection.
The paper focuses on the transient overvoltages imposed on compensation devices and equipment which are used at substation installations under faults on the adjacent electrical grid. Transient simulations determined hazards that impact the equipment insulation during transients occurred due to the faults. The results of the simulation studies should be used in determining the equipment ratings and...
This paper examines selected problems of planning of electric power network infrastructure development in Poland. Analysis of the process of planning of electric power network infrastructure development in Poland in legal, environmental and social area is shown. Moreover, the assessment of possibilities and effectiveness of solution applied in Poland for electric power network infrastructure planning...
This paper proposes three dimensions of characteristics to describe the shock load, including reactive power, time, rate of change, then established the simulation model to did deep analysis on the impact of the voltage quality problem for shock loads connected into distribution network, it focuses on comparing the different dimension characteristic due to the difference of the impact of the voltage...
In the paper the influence of conductive disturbances on transformation of fault current by inductive protective current transformers is described. Analysis of the results from laboratory studies show, that for such condition primary current up to which the current transformer will comply with the requirements for composite/ratio error is decreased. This is caused by increased magnetic flux density...
Accuracy requirements at harmonics are defined for electronic current transformers in IEC 60044-8 standard. As indicated there defined limiting values of current error ensure that the contribution of harmonics measurement error would add roughly 15%, in the worst case, on the theoretical error of the corresponding power metering class accuracy. In accordance with IEC 61000-3-12 standard total harmonic...
The paper discusses the possibility of obtaining the required parameters of Rogowski coils when apply of printed circuit board high density technology. Selected results of investigations are presented and examples of Rogowski coils for use in electrical power system protections are given.
As a result of the changes that occur in the electrical distribution networks, there is guidance tendency toward users, not only to power systems. This is a feature of the smart grid that will ensure safety operational and power quality, and also facilitates network connection of renewable source. Smart grid can intelligently integrate the behavior of all users connected to this network — electricity...
The paper describes three aspects of virtual market of electrical energy. Legislative base of alternative source using in energy-supply system including "green tariff" is presented. Calculation of economical parameters in order to estimate effectiveness of different alternative source is made. Technical solution for DC, AC, and hybrid energy transmission schemes are developed.
The paper presents an investigation of field oriented control strategy of Permanent Magnet Synchronous Motor (PMSM) based on hardware in the loop simulation (HIL) over a wide speed range. A sensorless rotor position estimation using sliding mode observer for permanent magnet synchronous motor is illustrated considering the effects of magnetic saturation between the d and q axes. The cross saturation...
Distance relay algorithms are typically based on the phasor-domain approach where the fundamental frequency phasors are computed using well-known methods such as: the full cycle discrete Fourier transformation (FCDFT), least error squares (LES) and the discrete wavelet transform (DWT). Instead of the phasor-domain approach, there are time-domain based algorithms that detect faults without calculating...
The increased voltage profile due to excess of reactive power in low load operation mode in power grid is observed. Because of HV overhead lines are distant from power generating sources and variable load curve, the voltage profile could grow over nominal level and at the same time power loss would increase. The last is caused by changed reactive power distribution at the system. Commutation process...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.