scholarly journals Evaluation of Methodology for Lightning Impulse Voltage Distribution over High-Voltage Windings of Inductive Voltage Transformers

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5144
Author(s):  
Bojan Trkulja ◽  
Ana Drandić ◽  
Viktor Milardić ◽  
Igor Žiger
Keyword(s):  
High Voltage ◽  
Equivalent Circuit Model ◽  
Boundary Element Methods ◽  
Design Stage ◽  
Iron Core ◽  
Voltage Distribution ◽  
Specific Design ◽  
Impulse Voltage ◽  
Lightning Impulse ◽  
Capacitance Matrix

Knowledge of lightning impulse (LI) voltage distribution over transformer windings during the design stage of the transformer is very important. Specific design differences in inductive voltage transformers make the transient analysis approach different to the approach to the power transformers. In this paper, a methodology for acquiring lightning impulse voltage distribution over high-voltage (HV) winding of inductive voltage transformers is presented and evaluated. Resistance, inductance, and capacitance matrices are calculated using the integral and boundary element methods (BEM) approach. Additionally, in order to improve the capacitance matrix solver, adaptive cross approximation (ACA) is applied. These parameters are then used to solve the equivalent circuit model in time domain. In order to evaluate the methodology, an experimental and numerical investigation of the layer discretisation, iron core influence, and accuracy of the proposed methodology is performed. The comparison of numerical results with measurements confirms the validity of the methodology.

scholarly journals Studying the Effect of Stray Capacitance on the Measurement Accuracy of the CVT Based on the Boundary Element Method

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Chuan Xiang ◽  
Xinwei Chen ◽  
Hongge Zhao ◽  
Zejun Ren ◽  
Guoqing Zhao
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
High Voltage ◽  
Measurement Accuracy ◽  
Equivalent Circuit Model ◽  
Structure Parameters ◽  
Stray Capacitance ◽  
Voltage Distribution ◽  
Voltage Transformer ◽  
Element Method

The capacitive voltage transformer (CVT) is a special measuring and protecting device, which is commonly applied in high-voltage power systems. Its measurement accuracy is affected seriously by the stray capacitances of the capacitance voltage divider (CVD) to ground and other charged parts. In this study, based on the boundary element method, a mathematical model was established firstly to calculate the stray capacitance. Then, the voltage distribution of the CVD was obtained by the CVD’s equivalent circuit model. Next, the effect of stray capacitance on the voltage distribution and the voltage difference ratio (VDR) of CVD was analysed in detail. We finally designed three types of shield and optimized their structure parameters to reduce VDR. The results indicated that the average deviation rate between calculated and experimental measured voltages is only 0.015%; that is to say, the method has high calculation precision. The stray capacitance of the CVD to ground is far larger than that of the CVD to the high-voltage terminal. It results in the inhomogeneous distribution of voltage and the increase of VDR. For the test CVT, its VDR exceeds the requirement of class 0.2. Among all of the three types of shield, the C type reduced the VDR of the test CVT the most. After optimizing the structure parameters of C-type shield, the VDR is further reduced to 0.08%. It is not only in accord with the requirement of class 0.2 but also has an adequate margin.

Lightning impulse voltage distribution over voltage transformer windings — Simulation and measurement

2017 ◽  
Vol 147 ◽  
pp. 185-191 ◽  
Author(s):  
Bojan Trkulja ◽  
Ana Drandić ◽  
Viktor Milardić ◽  
Tomislav Župan ◽  
Igor Žiger ◽  
...  
Keyword(s):  
Voltage Distribution ◽  
Voltage Transformer ◽  
Impulse Voltage ◽  
Lightning Impulse

scholarly journals Investigation on the Resonant Oscillations in an 11 kV Distribution Transformer under Standard and Chopped Lightning Impulse Overvoltages with Different Shield Placement Configurations

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1466 ◽  
Author(s):  
Murthy ◽  
Azis ◽  
Yousof ◽  
Jasni ◽  
Othman ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
High Voltage ◽  
Low Voltage ◽  
Stress Distributions ◽  
Voltage Distribution ◽  
Distribution Transformer ◽  
Resonant Oscillation ◽  
Initial Voltage ◽  
Transformer Winding ◽  
Lightning Impulse

This paper presents an investigation on the resonant oscillations of an 11 kV layer-type winding transformer under standard and chopped lightning impulse overvoltage conditions based on calculated parameters. The resistances, inductances and capacitances were calculated in order to develop the transformer winding equivalent circuit. The impulse overvoltages were applied to the high voltage (HV) winding and the resonant oscillations were simulated for each of the layers based on different electrostatic shield placement configurations. It is found that the placement of grounded shields between layer 13 and layer 14 results in the highest resonant oscillation and non-linear initial voltage distribution. The oscillation and linear stress distributions are at the lowest for shield placement between the HV and low voltage (LV) windings.

Transformer Windings’ Parameters Calculation and Lightning Impulse Voltage Distribution Simulation

2016 ◽  
Vol 52 (3) ◽  
pp. 1-4 ◽  
Author(s):  
Tomislav Zupan ◽  
Bojan Trkulja ◽  
Roman Obrist ◽  
Thomas Franz ◽  
Bogdan Cranganu-Cretu ◽  
...  
Keyword(s):  
Voltage Distribution ◽  
Impulse Voltage ◽  
Lightning Impulse ◽  
Parameters Calculation

scholarly journals DETERMINATION OF THE LEVEL OF OVERVOLTAGE IN THE SECONDARY CIRCUITS OF SUBSTATIONS WHEN LIGHTNING IMPULSE VOLTAGE IS DISTRIBUTED IN HIGH-VOLTAGE BUSES

2017 ◽  
Vol 60 (3) ◽  
pp. 211-227
Author(s):  
V. I. Glushko ◽  
E. A. Deryugina
Keyword(s):  
High Voltage ◽  
Relay Protection ◽  
Test Method ◽  
Secondary Circuit ◽  
Automatic Equipment ◽  
Method Of Calculation ◽  
Switching Overvoltage ◽  
Impulse Voltage ◽  
Lightning Impulse ◽  
The Time Domain

Lightning voltage impulse due to the waves of storm surge rolling out the high voltage line to a substation causes current to flow in the buses that, due to magnetic effect, induces overvoltage in the secondary circuit. Overvoltage in the system “wire – ground” is considered as obstructions which are hazard in relation to the possibility of electrical damage of the devices of relay protection and automation of substations. With the use of the inverse Laplace transformation, the solution of the problem the magnetic influence of the primary circuits to secondary circuits in the time domain depending on time of transition, which always occurs during the distribution of the voltage impulse in the buses, has been obtained. Estimation of the level of overvol tage in the system “wire – ground” for the case of failure of a bus nonlinear surges and arresters when lightning impulse of voltage is distributed on the buses along their length without deformation has been fulfilled. Solutions are obtained for overvoltage in the secondary circuits, according to which the levels of overvoltage can be estimated as “extremely stepped-up”, “lowered” and “averagely stepped-up” levels. With a method of computational experiment the levels of overvol tage for distribution substations with voltage 110 and 220 kV were assessed. The results are compared with the normalized values of the interference voltage. The suggested method of calculation of impulse magnetic influence of the primary circuits on the secondary circuits of substations while lightning impulse voltage is being distributed in high voltage buses for the case of failure of a nonlinear surge and arresters at the stage of design and operation of substations can be used as a test method for estimation of electrical durability of relay protection and automatic equipment from lightning and switching overvoltage.

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