DOI:10.1007/s40565-018-0387-3 |
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Evaluation of overhead lines current unbalance in meshed grids and its reduction |
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Net amount: 733 |
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Author:
Jakub EHRENBERGER1, Jan SˇVEC1
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Author Affiliation:
1. Department of Electrical Power Engineering, Czech Technical University in Prague, Prague, Czech Republic
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Foundation: |
This work was supported by the Grant Agency
of the Czech Technical University in Prague (No. SGS14/188/OHK3/
3T/13). |
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Abstract: |
This paper describes new methodology in the
current unbalance calculations in meshed grids. The
meshed grids, mainly the transmission ones, consist of
more parts connected together which are formed using
different conductor types, phase sequence arrangements,
tower constructions, and various number of lines on the
same tower. Therefore several computational challenges
arise in comparison with the widely discussed point-topoint
configuration. The methodology divides the grid into
a number of impedance matrices respecting all the self and
mutual impedances among all conductors and all parallel
lines. Another challenging issue for the lines impedance
description is changing the number of shield wires along
the line if the line is composed of several sections with
different tower configurations. For the current unbalance
calculation, shield wires must also be included in the
algorithms, and matrices of various dimensions can be
obtained. For the overall matrix description to be used,
dimensions of all matrices in final equations must be equal,
and therefore the virtual shield wires are created. To
compare more conductor transposition cases with each
other, the line loadings caused by voltage sources should be
equal. This is necessary mainly in case of meshed grids
where the supplying sources on different lines can have
strong mutual couplings. This can be achieved by an
appropriately designed optimization of the connected
voltage sources. |
Keywords: |
Current unbalance, Phase sequence
arrangement, Shield wire, Unbalance factor, Zero-sequence
set |
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Online Time:2018/11/11 |
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