Wyniki wyszukiwania - BazTech

1

Research on Current Interruption by Grounding switch Used in 750kV Double-circuit Transmission Lines

Shengchang J., Xiaobo O.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 4

109-114

EN

In order to interrupt electromagnetically and electro-statically inductive current with high amplitude, grounding switches are applied in double-circuit transmission lines. In this paper, the formula of the induced voltage and current are drawn under different condition of grounding switch installed on the maintenance line. In order to clarify the characteristics of every electrical parameter, after calculating the capacitance and inductance matrix of 750kV double circuit transmission lines, simulation research is conducted using EMTP-ATP. Inductive voltage and current of 750kV doublecircuit transmission line are calculated and analyzed. Furthermore, in order to classify the worst switching parameter of grounding switches, the steady-state currents and the transient recovery voltage (TRV) are also calculated and analyzed. And then, the tests of capacitive and inductive current interruption for a 800kV grounding switch are also carried out in the laboratory. The results of the simulation and experiment in this paper provide guiding opinions for selecting grounding switches used in the 750kV double-circuit transmission lines.

PL

W pracy określano zależności prądu i napięcia indukowanego w uziemionym przełączniku przy różnych warunkach pracy. Obliczono pojemność i indukcyjność linii transmisyjnej 750 kV a następnie symulowano przebiegi prądów.

2

Study on transformer tank vibration characteristics in the field and its application

Shengchang J., Lingyu Z., Yanming L.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 2

205-211

EN

Vibration signal analysis method is one of effective methods to monitor the condition of transformer windings and core. In this paper, the multi-channels vibration measurement system is set up and the vibration signals on the oil-tank surface of running transformer in the field are measured. The influences of transformer type and sensor positions on the measured vibration signals are analyzed. The results show that, the same type of transformer' oil tank vibration signals have almost same characteristics, and the vibration signals measured on a transformer tank surface have similar characteristics only at the same position of phase "A" (or "a") and "C" (or "c"). Moreover, the attachment position of each sensor should be marked on the tank surface with paint, which is the reference position in the next measurement. It was recommended that the permissible error in the position of the sensor is within 5 cm. The vibration characteristics acquired in the field are applied to diagnose a transformer suffered three-phase short circuit, and the results presented show the accuracy and efficiency of the acquired transformer tank vibration characteristics.

PL

Analiza sygnału wibracji jest jedną z metod monitorowania stanu uzwojeń. i rdzenia transformatora. W artykule zastosowano wielokanałowy analizator wibracji do badania pracującego transformatora. Analizowano wpływ pozycji czujnika dla różnych typów transformatora. Stwierdzono, że sygnały wibracji miały podobny charakter dla jednego rodzaju transformatora i że sygnały są podobne dla tej samej pozycji czujnika. Rekomendowane jest więc zaznaczanie pozycji czujnika (z tolerancją. 5 cm) dla otrzymania powtarzalności pomiarów. Otrzymane sygnały wibracji mogą być wtedy wykorzystywane do diagnostyki.

3

Design of Measurement System and Characteristics Research on the Pulse Current of Composite Insulator

Shengchang J., Yuanyuan W.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 12a

133-139

EN

The composite insulators have been widely used on the power transmission lines. The faulty caused by manufacture techniques, quality defect or organic material degradation comes into being more and more. Measuring the composite insulator' corona pulse current flowing through the grounded wire is an excellent way to monitor the faulty insulator strings on ground. In this paper, the measurement system for detecting pulse current of composite insulator are set up. The wideband current transducer, extraction circuit of pulse current and the circuit of reference signal are designed and manufactured. Based on the experimental system set up in the laboratory, the characteristics of corona pulse are studied. The relationship between applied voltage and pulse current characteristics, the frequency and phase angle range of corona pulse are studied profoundly. Such work provides direction for on-line monitoring composite insulators by pulse current method.

PL

W artykule analizowano metody badania defektów izolatorów kompozytowych. Mierzono impulsowy prąd wyładowania przepływający przez uziemiony przewód. Przedstawiono układ pomiarowy tego prądu oraz przedstawiono wyniki eksperymentów. Analizowano związek między przyłożonym napięciem a prądem wyładowania, w tym właściwości częstotliwościowe i fazowe tego prądu.

4

Chaotic characteristics of time series of partial discharges in oilpaper insulation and their applications in pattern recognition

Yongfen L., Junhao L., Ping H., Shengchang J., Yanming L.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 7

219-224

EN

In order to recognize partial discharges (PD), five kinds of typical defects in oil-paper insulation are built and measured with current pulse method, and chaos method is used to research the time series of PD signals. The results revealed that the PD is of obvious chaotic characteristic, and the PD process is chaotic one. The PD patterns can be qualitatively analyzed and recognized by using the chaotic time series of PD and their chaotic attractors. Phase space reconstruction parameters and post-reconstruction chaotic characteristic quantities can be selected to quantify the PD's chaotic characteristics. Verification and comparison on pattern recognition effects of PRPD and CAPD were performed respectively by adopting the neural network of radial basis function (RBF), and the result showed that the effects of both were good and had their own advantages. Besides, statistical operators in PRPD mode and chaotic characteristic quantities in CAPD mode were comprehensively selected as the input vectors of neural network, and the average recognition rate can reach 95%, this result showed that the recognition on PD was improved by a relatively large scale.

PL

Przeprowadzono badania pięciu typowych przypadków defektów izolacji papierowo-olejowej. Sygnały wyładowań niezupełnych przetworzono w szeregi czasowe. Stwierdzono że process ma character chaotyczny. Wykorzystano teorię przebiegów chaotycznych do analizy sygnału i klasyfikacji wad.