NIZKONAPETOSTNA ARHITEKTURA ZA UPRAVLJANJE PAMETNIH OMREŽIJ

MOČNIK, JURE (author), Žemva, Andrej (mentor)

Doktorska disertacija obravnava temo postavitve nizkonapetostne arhitekture elektroenergetskega sistema za namen pametnih omrežij. V njej je predstavljen celotni vidik upravljanja z električno energijo, pri čemer največ pozornosti posveča načinu zajemanja informacij, na algoritem za uravnavanje napetostnega profila in na zmanjševanje porabe električne energije končnega uporabnika. Novi izzivi, ki so pred elektroenergetskim sistemom, so obvladljivi le s pomočjo popolne informatizacije distribucijskega omrežja, kar pomeni, da bodo elementi omrežja med seboj informacijsko povezani. Trenutno sta z informacijskimi sistemi za nadzor in vodenje pokrita le visokonapetostno (VN) in deloma srednjenapetostno (SN) omrežje. Nizkonapetostno (NN) omrežje trenutno še ni pokrito, kar pomeni, da ni vzpostavljena informacijska povezava z veliko večino končnih uporabnikov omrežja, tako na sektorju porabe kot tudi razpršene proizvodnje električne energije. Informacijska komunikacijska infrastruktura (IKT) ima v pametnih omrežjih pomembno vlogo pri zmanjševanju izgub, zagotavljanju človekove varnosti in povečevanju učinkovitosti, stabilnosti in varnosti celotnega distribuiranega elektroenergetskega sistema. Enostavno povedano: brez komunikacijske infrastrukture pametno omrežje ne more obstajati, saj IKT namreč s pomočjo pametnih naprav in različnih algoritmov poskrbi, da so informacije o distribucijskem omrežju vedno na voljo in na zahtevanem mestu. V okviru izgradnje elektroenergetskega omrežja je zato potrebno poskrbeti za ustrezen pretok informacij, torej za ustrezno IKT, ki bo segala vse do končnih uporabnikov omrežja. Informacijska infrastruktura je nujna tudi za povezavo razpršenih virov (RV) in nekaterih uporabnikov v tako imenovane virtualne elektrarne, ki bodo poskrbele za poenostavljen nadzor, vodenje in zagotavljanje sistemskih rešitev nad RV, ki bodo pripomogli k zagotavljanju stabilnosti in zanesljivosti omrežja. Zelo pomembno vlogo v konceptu pametnih omrežij ima tudi uporabniška stran, in sicer končni uporabniki (vključno z gospodinjstvi), saj se bodo preko tržnih paketov oskrbe aktivno vključili v učinkovito rabo energije. Disertacija predstavlja platformo za pametna omrežja, ki sloni na dvoslojni komunikacijski arhitekturi (IP/MPLS – angl. internet protocol/multi-protocol label switching, ki podpira veliko število navideznih omrežij, zančno ter obročno topologijo itd.). Platforma vzpostavi komunikacijo med dobavitelji, distribucijo in odjemalci v realnem času, hkrati pa uporablja enotni protokol – IEC61850. Za zajem podatkov na visokonapetostnem nivoju je predstavljena nova metoda z uporabo nekonvencionalnega kombiniranega instrumentalnega transformatorja. Ta ima glavno tehnološko prednost v elektronskem vezju in merilnem postopku merjenja napetosti ter toka (in posledično vseh parametrov) brez uporabe visokonapetostnega tokovnega transformatorja. Njegova prednost je tudi v tem, da tokovni del »lebdi« med zemljinim in visokonapetostnim potencialom, in da se za meritve uporablja nizko-napetostni tokovni transformator. S predlagano metodo merjenja je omogočeno merjenje signalov na višjih frekvencah s predvidevanjem faznega zamika, kar omogoča harmonično analizo električnega omrežja. Predlagan transformator ima prednosti pred konvencionalnimi tudi v dimenzijah, kompatibilnosti s standardom IEC61850-9-2 (ki se uporablja za krmiljenje novih digitalnih odklopnih sistemov), v zmanjšanju porabe dragocenih kovin in transformatorskega olja, kar posledično pomeni, da ob prebitju transformator ne onesnažuje okolja. Disertacija predstavlja tudi novo metodo zmanjševanja porabe električne energije končnega uporabnika, ki temelji predvsem na brezžičnem upravljanju naprav. Porabo bo možno nadzirati s pomočjo aplikacije, ki upravlja naprave glede na geodetski in električni položaj uporabnika v distribucijskem omrežju (DO) ali pa s shemo razbremenjevanja (angl. load shedding). Za ta namen sta bili razviti spletna in android aplikaciji, ki upravljata s pametnim sprejemnikom in pametnimi stikali, ki so nameščeni v »pametnem domu«. Predstavljen je tudi nov algoritem za uravnavanje napetostnega profila DO, v katerem so nameščeni RV. Prednost tega algoritma pred obstoječimi je v izboljšani napovedi proizvodnje delovne moči RV, izboljšane razporeditve delovne moči in omogočanju priklopa vseh RV, ne glede na njihovo instalirano moč ali mesto priklopa. Algoritem s pripadajočim sistemom v sistem prinese tudi vmesnike stičnega mesta, ki hkrati beležijo v stanje omrežja, zaznavajo napake na SN in NN omrežju ter transformatorskih postajah - TP (prekinitve vodnikov, prekinitve polizoliranih vodnikov, prekinitev varovalk itd.), kar posledično povzroči hitrejše odpravljanje napak in zagotavljanje višje kakovosti električne energije. Algoritem predvideva tudi delovanje distribucijskega omrežja v otočnem načinu, kar trenutno po zakonodaji ni splošno omogočeno (samo pod posebnimi pogoji) [64] [65]. Vendar menimo, da se bo za namen pametnih omrežji to moralo kmalu spremeniti.

• Language: Slovenian
• Keywords: algoritem za uravnavanje napetostnega profila, IEC61850, MiSMART, nekonvencionalni instrumentalni merilni transformator, zmanjševanje porabe električne energije, pametni sprejemnik, pametno omrežje, pametno stikalo, vmesnik stičnega mesta
• Work type: Doctoral dissertation
• Organization: FE - Faculty of Electrical Engineering
• Year: 2015
• PID: 20.500.12556/RUL-30703
• COBISS.SI-ID: 11000148
• Publication date in RUL: 22.04.2015

Secondary language

• Language: English
• Title: LOW VOLTAGE ARCHITECTURE FOR SMART GRID MANAGEMENT

Abstract

My doctoral dissertation addresses the topic of installing low-voltage architecture of electric power system for smart grids. The study presents all aspects of managing electric energy but the focus is on the method of gathering information, on the algorithm for balancing the voltage profile and on the reducing of consumers’ electric energy usage. New challenges that stand in front of the electric power systems can only be mitigated with the help of complete computerization of the distribution network, therefore their elements should be interlinked. The computerization for control and management coverage extends only to high-voltage grids but the medium-voltage grids are only partially covered. At the moment the low-voltage network is not included, which means that the information link to a large amount of consumers is not established both on the spending sector as well as the widespread electric energy production. Informational communication infrastructure plays an important role in smart networks as it participates with loss reduction, safety assurance and efficiency increase in the whole electric power system. Bluntly put, there can be no smart networks without the communication infrastructure. When constructing an electric power network the needed flow of information should be assured – therefore the informational communication technology has to achieve the necessary standards and reach all network users. Informational infrastructure is also essential for the connection of widespread sources and some users into so-called virtual power plants that provide simplified control, guidance and assurance of systemic solutions for widespread sources. It is of utter importance for safe and unfaltering performance of electric power network as the virtual power plants’ narrow access points can interfere with the flow input. It can also guarantee necessary voltage profiles, regulate reactive power and offer control over the distributed energy resources and the possibility of creating intentional islanding. A vital role in the smart network concept is the consumer side, more precisely the end user (including households), as they will actively participate in the managing of end energy via energy efficiency packages. The dissertation introduces a platform for smart networks, based on dual-layered communication architecture (IP/MPLS, which supports a large number of virtual networks and also the loop and ring topology, etc.) The platform establishes communication between suppliers, distributors and customers in real time, but at the same time uses a unified protocol – IEC61850. There is a new method for the intake of data on a high-voltage level which uses non-conventional instrument transformer that has a major technological advantage in electronic circuits and in the voltage and current measuring procedure (therefore all parameters) without the usage of high-voltage current transformer. Its advantage lies also in the fact that the current part “floats” between the grounded and high-voltage potential, and is compatible with low-voltage transformer measuring devices. With the proposed method of measuring you enable the mapping of signals on a higher frequency with foresight of phase discrepancies which permits a harmonic analysis of electric networks with higher harmonics. The suggested transformer possesses advantages over the conventional ones even in dimensions, compatible with the IEC61850-9-2 standard (it is used for control of new digital disconnection systems), in the reduction of consumption of valuable metals and transformer oils, which in turn means a maximization of transformer security. This thesis represents a new method of electric energy usage optimization for the end user, which bases mostly on wireless appliance control. It will be possible to control them through an application which operates the devices based on the geodetic position of the user or with a network alleviation scheme. An application was developed with this purpose in mind for the internet and for Android operation systems that engages with the smart receiver and smart switches that are installed in the smart house or apartment. A new algorithm was also introduced for controlling the voltage profile of the distribution network where the spread sources stand. The prevalence of this algorithm is in better power organization and does not use any reactive power injections, algorithms for control of active and reactive power, voltage regulators, voltage compensators and algorithms for power factor supervision. Together with the corresponding system it brings control interfaces to the structure which simultaneously registers the network status and instantly prompts errors, causing more efficient removal of faults and ensuring much higher electric energy quality. The algorithm also includes an idea of the distribution network process in an island mode which is not generally possible under the law (just under special condition) but we believe that for the purpose of smart networks this should soon be changed.

• Keywords: Algorithm for voltage profile control, IEC61850, MiSMART, non-conventional instrument transformer, point of common coupling interface, reducing power consumption, smart grid, smart receiver, smart switch