Kalkulawa da Dabi a Fisikin Kashi | Zama Zabi na Rubutu na Tsaki na Sifili

Idan da amfani da hanyar inganci na kula daidai, yana bukata a gane wani yanayin cikakken kula a lokacin da ake yi. A takaice, ana bukata a gane wani yanayin cikakken kula don ya amfani da hanyoyin inganci daban-daban a wurare daban-daban na kulan kula.

Bayanai game da uku da kadan da suka shafi kula, tsari a lokacin da suka shafi tsari a wurare daban-daban na kulan kula, zai iya gaya don ya amfani da hanyar inganci a wurare daban-daban na kulan kula. Koyarwa bayanai daga parametere daban-daban na system yana nufin amfani da bayanai game da wani yanayin cikakken kula.

Amfani da bayanai game da wani yanayin cikakken kula ta nufin amfani da kula kula a wani kulan kula. Ana samun uku wasu abubuwa don amfani da bayanai game da wani yanayin cikakken kula a wani system.

1. Zabi na maimaita da za a yi kan impaniyar kula.

2. Kawo system mai karfi na kulan kula zuwa impaniyar kula mafi girma.

3. Amfani da kula da tsari a lokacin da ake shafi kula da tsari ta amfani da hukumomin symmetrical component theory.

Impedance Notation of Electrical Power System

Idan a duba kulan kula, zan iya samun, akwai uku daban-daban. Misali, idan a duba wani kulan kula na musamman, inda ake shiga kula a 6.6 kV, sannan an fara 132 kV, kuma an fara a terminal substation inda an kara tsaro zuwa 33 kV da 11 kV, kuma 11 kV zai iya kara tsaro zuwa 0.4 kv.

Daga wannan misali, yana bayyana cewa wani kulan kula na musamman zai iya da uku daban-daban. Saboda haka, amfani da bayanai game da wani yanayin cikakken kula a wurin da ke da su yana bazu da ma'ana, kuma yana bukata a gane impaniyar kula na wurare daban-daban kamar hukumar uku.

Wannan bukatar yana iya zama lafiya idan ake amfani da impaniyar kula na wurare daban-daban a kan daya da aka fada. Wannan tushen yana nufin impedance notation na kulan kula. Idan kuma a takaice, amfani da bayanai game da wani yanayin cikakken kula, bayanan system, zai iya haɗa base quantities kuma ya shiga cikin uniform system of impedance a ohmic, percentage, ko per unit values.

Kula da tsari suna haɗa da base quantities. A three phase system, three phase power a MVA ko KVA zai haɗa da base power, sannan tsari a line to line voltage a KV zai haɗa da base voltage. Base impedance na system zai iya samun daga wannan base power da base voltage, kamar haka,

Per unit shine impaniyar kula na system ba ƙasashe ba, amma radio na impaniyar kula na system zuwa base impedance value.

Percentage impedance zai iya samun ta bayarwa 100 da per unit value.

Sai dai, yana bukata a takaice a kawo per unit values zuwa base values masu sabon bayanai don sauka amfani da bayanai game da wani yanayin cikakken kula. A wannan lokacin,

Zabin impedance notation tana neman ne daga sabbin system. Ba ƙasashe ba, base tsari na system tana haɗa da ita cewa yana bukata a takaice a takaice a kan transfers.
Misali, idan a duba wani system da ke da uku 132 KV overhead lines, kowane ƙasa 33 KV lines, da kowane ƙasa 11 KV lines. Base tsari na system zai iya haɗa a 132 KV, 33 KV, ko 11 KV, amma a wannan lokacin, base tsari mafi yawan faɗa 132 KV, saboda haka yana bukata a takaice a kan transfers a lokacin amfani da bayanai game da wani yanayin cikakken kula.

Network Reduction

Ba a zabi na maimaita da za a yi kan impedance notation, abin da ke na biyu shine kawo network zuwa impaniyar kula. Don haka, karkashin da muke so kuɗi shine kawo impaniyar kula na generators, lines, cables, transformer zuwa base value mafi girma. Sannan muna samun diagram mai sauƙi na kulan kula wanda ya shiga impaniyar kula na generators, lines, cables, da transformers zuwa base value mafi girma.

An kawo network zuwa equivalent single impedance mafi girma ta amfani da star/delta transformations. Diagrams masu impaniyar kula suna buƙaci a kan positive, negative, da zero sequence networks.

There phase faults suna nufin cewa su na iya samun daga single phase positive sequence impedance diagram, saboda haka three phase fault current zai iya samun ta,

Inda, I f shine total three phase fault current, v shine phase to neutral voltage, z 1 shine total positive sequence impedance na system; assuming that in the calculation, impedance are represented in ohms on a voltage base.

Symmetrical Component Analysis

Amfani da bayanai game da wani yanayin cikakken kula a takaice a kan three phase balanced system. Amfani da bayanai game da wani phase ne kawai saboda amfani da bayanai game da currents da tsari na dukkan phases.

Idan wani yanayin cikakken kula yana faru a kulan kula, kamar phase to earth fault, phase to phase fault, da double phase to earth fault, system yana zama unbalanced, cewa amfani da bayanai game da tsari da currents na dukkan phases ba su iya samun daga symmetrical. Wadannan faults suna haɗa da symmetrical component analysis.

Ba ƙasashe ba, three phase vector diagram zai iya haɗa da uku sets of balanced vectors. Wanda babu opposite ko negative phase rotation, wanda babu positive phase rotation, da wanda babu co-phasal. Cewa wadannan vectors sets suna nufin negative, positive, da zero sequence, respectively.

Equation between phase and sequence quantities are,

Therefore,

Inda dukkan quantities suna haɗa da reference phase r.
Amma, set of equations zai iya rubuta don sequence currents. Daga, tsari da current equations, one can easily determine the sequence impedance of the system.

The development of symmetrical component analysis depends upon the fact that in balanced system of impedance, sequence currents can give rise only to voltage drops of the same sequence. Once the sequence networks are available, these can be converted to single equivalent impedance.

Let us consider Z1, Z2 and Z0 are the impedance of the system to the flow of positive, negative and zero sequence current respectively.
For earth fault

Phase to phase faults


Double phase to earth faults

Three phase faults

If fault current in any particular branch of the network is required, the same can be calculated after combining the sequence components flowing in that branch. This involves the distribution of sequence components currents as determined by solving the above equations, in their respective network according to their relative impedance. Voltages at any point of the network can also be determined once the sequence component currents and sequence impedance of each branch are known.

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