Nowa metoda kompensacji efektu opóźnienia transmisji danych dla potrzeb prądowo-różnicowych zabezpieczeń linii przesyłowych

This paper is concerned with the problem of accurate aligning of digital data for purpose of feeder differential current protection. The method proposed makes use of knowledge of line susceptance for estimating the communication channel propagation time. The performance of the method is investigated under variable operational conditions of the 400 kV overhead transmission line. The outcomes show high efficiency of the approach allowing for essential improvement of sensitivity of a percentage differential protection.W artykule zaprezentowano nowa metodę synchronizacji danych przesyłanych kanałem teleinforma-tycznym dla potrzeb przekaźników różnicowoprądowych napowietrznych linii elektroenergetycznych. Szacowanie opóźnienia przesyłu danych dokonywane jest na podstawie znajomości susceptancji linii oraz lokalnego pomiaru napięcia, lokalnego prądu fazowego i przesłanego prądu z przeciwległego końca linii w warunkach przedzwarciowych. Dokładność metody została sprawdzona dla różnych stanów pracy dwutorowej napowietrznej linii 400 kV. Wyniki badań potwierdzają dużą dokładność szacowania i tym samym korekcji kątowej między prądami z obu końców linii. Opracowana metoda kompensacji pozwala na zasadniczą poprawę czułości zabezpieczenia różnicowego linii przesyłowych

Fault location of power transmission lines using artificial neural network

The article presents the method of fault location on power transmission lines passed on artificial neural networks. Determination of fault place is based on knowledge of the fault type and measurements of voltage and current magnitudes from one end of the line. The accuracy of the method was tested for different operating conditions of 400kV power transmission line. The results confirm the high accuracy of the proposed method

Location of arc faults on power transmission lines

This paper presents a fault location algorithm, which allows to determine the distance to a fault and fault resistance, as a result of considering natural fault loops. It is assumed that three-phase voltages and currents from both ends of the line measured asynchronously are the input signals of the fault locator. In case of the availability of synchronized measurements the elements associated with the determination of the synchronization angle should be omitted. In addition to natural fault loop signals also use of symmetrical components (positive and negative or incremental positive sequence components) to fault location were considered as well

PQ Cootrol of Photovoltaic Power Statioo in Microgrid Operation

The numerical modelling of the photovoltaic module and the solar inverter interconnected with the microgrid has been carried out with the use of PowerSys in Matlab/Simulink. Algorithms of P, Q controllers have been proposed. The capability of the active and reactive power reference tracking has been tested for various conditions

Analysis of Synchrophasor Estimatioo Errors

This papers discusses the analytical analysis of the syochrophasor estimation employed in electrical systems. Short time Fourier trsnsform with the phase locked loop and Taylor Fourier series are analyzed for signals relating to different states which may occor in real power systems. The object is the accurate phasor estimation regardless of the shape of input signal, what for some signal types is cumbersome. As a result of active and reactive power disturbance in a power system, the frequency deviation and amplitude fluctuations may appear in power system signals. As a consequences of short circuits or overvoltages signal changes occur. Ibis leads to unacceptable errors in short time Fourier transform resulting from Fourier transform properties. This paper presents character of occurring errors and their consequences individually for any signal deviation

Neural network filtration for arc faults location on power transmission lines

This paper presents filtration using neural network for arc fault location, which allows to determine the distance to a fault, as a result of considering natural fault loops. It is assumed that three-phase voltages and currents from both ends of the line are the input signals of the fault locator and naturally of the neutral network applied for filtering the input signals. In addition to natural fault loop signals also use of symmetrical components (positive and negative or incremental positive sequence components) to fault location were considered as well. Results of evaluation study have been included, analyzed and discussed. Influence of filtration has been also considered

Analiza możliwości poboru pary z turbiny bloku kondensacyjnego 900 MW do instalacji separacji CO2

The paper presents the requirements for a carbon dioxide separation system based on chemical absorption in terms of the heat quantity as well as the heating medium needed for the sorbent regeneration. The possibilities of steam extraction from the turbine to supply the carbon dioxide separation system were analyzed. The power plant indicators for diverse sorbents were determined. The possibilities of steam turbine modifications after its integration with the separation system and the changes in the feed water heating system were discussed. The impact of the assumed configuration of the low pressure turbine on the scope of its restructuring was presented. The calculations were performed for a 900 MW supercritical coal-fired condensing unit. Also, the possibility of heat extraction from the boiler exhaust gases for the separation system was considered.Przedstawiono wymagania instalacji separacji CO2 metodą absorpcji chemicznej w zakresie ilości ciepła oraz parametrów czynnika grzejnego, potrzebnego do regeneracji sorbentu. Analizowano możliwości poboru pary z turbiny do zasilania instalacji separacji CO2. Określono wskaźniki pracy bloku dla różnych sorbentów. Przedstawiono możliwości przebudowy turbiny po zintegrowaniu bloku z instalacją separacji oraz związane z tym zmiany w układzie regeneracji. Analizowano wpływ przyjętej konfiguracji części niskoprężnej turbiny na zakres jej przebudowy. Obliczenia zostały przeprowadzone dla nadkrytycznego kondensacyjnego bloku węglowego o mocy 900 MW opalanego węglem kamiennym lub brunatnym. Analizowano również możliwości poboru ciepła do instalacji separacji ze spalin wylotowych z kotła