Kompenzacija jalove moči večjega industrijskega odjemalca in njen vpliv na napetost v prenosnem omrežju

CIGLAR, ROK (author), Blažič, Boštjan (mentor)

V magistrskem delu ki je pred vami, je temelj obravnave vpliv pretokov moči na napetosti v omrežju. Predvsem nas bo zanimal vpliv pretoka jalove energije, ter na kakšen način in v kakšni meri lahko s spremembo slednje vplivamo na napetost. Vse skupaj bo predstavljeno na realnem primeru Slovenskega omrežja, natančneje na 110kV visokonapetostnem omrežju Pomurske zanke. Problem s katerim se soočamo in je v tem delu še posebej izrazit so visoke napetosti, kadar je potrošnja električne energije nizka. Tukaj kot rešitev nastopi največji porabnik električne energije v Sloveniji podjetje Talum d.d., kateri s spremembo obratovalnega stanja kompenzacijskih naprav znižuje napetosti celotne Pomurske zanke in s tem vzdržuje napetosti znotraj normalnih meja. Namen naloge je torej ugotoviti, kako Talum vpliva na napetosti v Pomurski zanki, oziroma kakšne so številčne vrednosti sprememb napetosti, zaradi preklopov kompenzacijskih naprav. Začetni del naloge zajema osnovne relacije med elektrotehničnimi veličinami, katerih razumevanje je potrebno če želimo razumeti vpliv pretokov moči na napetost oziroma napetostno stabilnost. Na slednjem poglavju je narejen večji poudarek, kjer so s pomočjo enostavnega modela omrežja izpeljane enačbe, na podlagi katerih so nato izrisani grafi in krivulje za lažjo predstavo obravnavanega problema. Prav tako je na kratko predstavljena tudi kompenzacija jalove energije, kjer je pokazano na kakšen način lahko vplivamo na pretok jalove energije in kakšne so posledice vpliva. V nadaljevanju je podrobneje predstavljeno električno omrežje Talum, kjer je opisano od kod se omrežje napaja, ter kako je omrežje Talum razdeljeno. Na podlagi te delitve je nato opravljen podroben tehnični opis transformatorjev ter kompenzacijskih naprav. Prav tako so v sklopu tega poglavja predstavljeni podatki o odjemu električne energije podjetja za leto 2014, kjer so ponovno glede na delitev omrežja predstavljeni posamezni pretoki delovne in jalove energije, ter na koncu še skupni odjem. Podobno kot v prejšnjem poglavju je opravljen tudi opis kako je sestavljena Pomurska zanka, v katerem je opisano katere razdelilne transformatorske postaje (RTP) vse nastopajo, kakšne so povezave med njimi, ter kateri vodi so na višjih napetostnih nivojih kot je naš opazovan, saj je na podlagi opisanega omrežja tudi sestavljen simulacijski model. Prav tako je na tem mestu predstavljeno kako sem na podlagi pretokov energij za leto 2014 prišel do moči, katere sem kasneje uporabil v simulaciji in izračunih. Na podlagi opisa uporabljenih elementov omrežja in moči je nato prikazana primerjava rezultatov simulacijskega modela in meritev, tako moči kot napetosti, s čim sem lahko potrdil da je omrežje pravilno zmodelirano in pravilno umerjeno. Sledi predstavitev napetosti vseh RTP-jev, kjer je pokazano katere so najvišje napetosti ki se pojavljajo v omrežju, in koliko je procentualno takih, ki se nevarno približujejo zgornji napetostni meji. Na tem mestu sem nato določil točke napetosti v Talumu, pri katerih sem nato v simulaciji postopoma izklapljal kompenzacijo po stopnjah, in opazoval kako se spreminja napetost po vsem RTP-jih v Pomurski zanki. Sledi predstavitev rezultatov simulacije, kjer so rezultati podani za posamezno RTP v obliki stolpičnih diagramov, prav tako pa so rezultati podani v obliki tabele, v kateri je prav tako za vsak RTP podana začetna napetost, in nato v skladu z izklopom kompenzacije padec napetosti, kateri je podan tako v števčni vrednosti, kakor tudi procentualni. Za občutek je podana tudi maksimalna razlika napetosti, to pomeni razlika med začetno napetostjo, ko je bila vklopljena celotna kompenzacija in končno napetostjo, ko so bile iz obratovanja izvzete vse stopnje kompenzacije. Kot zaključek je podan še ekonomski vidik regulacije napetosti, kjer je na podlagi dogovorjenih cen za leto 2014 izračunano, koliko bi podjetje Talum lahko zaslužilo, če bi bile podpisane pogodbe in dogovori, ki veljajo vse od leta 2016.

• Language: Slovenian
• Keywords: pretoki moči, jalova moč, kompenzacija jalove moči, napetostna stabilnost, regulacija napetosti
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2018
• PID: 20.500.12556/RUL-100932
• Publication date in RUL: 24.04.2018

Secondary language

• Language: English
• Title: Reactive power compensation of a larger industrial customer and its impact on transmission-network voltage

Abstract

This master's s thesis is concerned with the effect of power flow on the voltage in electrical grids. The thesis focuses mainly on the effect of the flow of reactive power and in what way and to which extent we can regulate voltage by adjusting the flow of reacting power. These effects will be presented based on an example from Slovenian electrical grids, more specifically on a 110 kV high-voltage electrical grid of the Pomurje electric loop. The main problem we are faced with in this region is the problem of high voltage when electricity consumption is low. The biggest consumer of electricity in the region, company Talum d.d., offers a solution. They are able to reduce the voltage of the entire Pomurska loop and maintain the voltage within normal levels by changing the operating condition of their compensation devices. The purpose of this master's thesis is to present how Talum is able to affect the voltage in the Pomurje loop and determine the exact numeric values of the changes in voltage that are the result of switching off the compensation devices. The beginning of the thesis explains the basic correlations between electrical quantities which are important for the understanding of the effect of power flow on voltage, more specifically on voltage stability. The greatest emphasis is put on the construction of a simple model of the electric grid based on which the equations are derived. The derived equations are the basis for the graphs and curves presented in the master's thesis. The graphs and curves help with the better understanding of the topic. The compensation of reactive power, where possible methods of affecting the flow of reactive power and the effects of such actions, are also presented. This is followed by a detailed description of Talum's electric grids. Where the power supplied from and how the electric grid is set up is presented. Based on the electric grid scheme a detailed technical description of the transformers and compensation devices is made. The flow of active and reactive power and total consumption of the company is calculated based on the electric grid scheme and the consumption of electricity in 2014. As previously the Pomurje loop is described in detail. The description includes the types of electrical substations in the electric grid, how they are connected and which power lines have higher voltage levels than the observed one, since this is the basis for the simulation model. Here it is also explained how the power values are derived based on the energy flow for the year 2014. This data was later used in the simulation and the calculations. The description of the used elements of the electric grid scheme is the basis for comparison of the results given by the simulation models and the measurements of power and voltage. The comparison enabled me to confirm that the simulation model was set up and configured correctly. The next part shows the voltage in all electrical substations. The data presented shows the highest voltage levels in the electrical grid and the percentage of those where the levels are close to critical. At this point I determined the voltage points in the company Talum where I gradually turned off compensation by levels and monitored the changes in electrical substations throughout the Pomurje loop. The results of the data collected for each electrical substation are presented in column diagrams and in a form of a table which includes the initial voltage and the drops in voltage values that are in accordance with switching off the compensation. The values are presented numerically and in percentage terms. The maximum difference between the initial voltage, when the complete compensation was on, and final voltage, where all levels of compensation were taken out of the picture, is given to make the understanding of the data clearer. To conclude the thesis the economic outlook of voltage regulation is presented. This includes the calculation of the company's profit based on the agreed prices in 2014 in comparison with the contracts concluded in 2016.

• Keywords: power flow, reactive power, compensation of reactive power, voltage stability, voltage regulation