Metode za spoznavnost in odzivnost pametnih omrežij z uporabo inteligentnih elektronskih naprav

For some time now, we have been observing clear trends of climate change all over the world that are disturbing the delicate balance of the ecosystem to a not inconsiderable degree. While some tend to attribute these phenomena to processes on the scale of a geological era, i.e., to enormous cyclical climate fluctuations over millions of years, others claim that the industrial and agricultural activities of recent decades have had influence on this process by releasing an unprecedented amount of greenhouse gases into the atmosphere. This is primarily a consequence of the widespread use of fossil resources as a source of energy, particularly for electricity generation. The limited availability of fossil resources and their impact on the ecosystem are among the most important factors that require an economy based on the use of renewable and clean energy, which can provide a sufficient guarantee of sustainability in the long term. To achieve this, the current electric power system is undergoing significant changes, mainly through the massive integration of renewable sources. Conventional power generation plants (especially thermal) are being decommissioned and replaced by decentralised, sustainable and renewable energy sources, especially wind and solar power plants. While this energy transition brings significant environmental benefits, it also leads to increased complexity of the power system, resulting in unprecedented power system behaviour and new operational challenges. More than ever, electricity is an integral part of our daily lives, so prolonged power outages have significant negative social and economic consequences. In this context, this thesis addresses the real-time observability of the electric power system and the preventive and response measures used to mitigate the consequences of power outages for consumers. In the first part, the emerging smart grids and their challenges are briefly presented and their characteristics compared to the conventional power system are outlined. Then, the legacy SCADA monitoring system and the current state-of-the-art synchronised monitoring technology, enabled by phasor measurement units, are introduced. Here, the theoretical background and main advantages of phasor technology are explained, as well as considerations for its proper use in real applications. Next, the basis of one of the applied preventive protection measures related to the frequency stability of the power system, i.e. under-frequency load shedding, is explained in more detail and a novel scheme for its triggering is proposed. In addition, the effectiveness of the scheme is verified through hardware-in-the-loop testing and further developed for applicability in the real-environment. The next chapter shows the importance of power system protection and explains the need for quick fault localization. An extension of the fault localization algorithm is proposed that increases the precision of fault localization and is able to classify the fault type and determine the fault impedances while also requiring fewer measurement units to do so. Furthermore, this chapter presents a framework required for the successful implementation of the proposed algorithm in a real environment. At the same time, the framework reduces the amount of data transmitted over the wireless communication network, thereby lowering the operating costs of the distribution system operators. Finally, the conclusions summarise the main results of the thesis.Že nekaj časa povsod po svetu opažamo jasne trende podnebnih sprememb, ki v nezanemarljivi meri vplivajo na občutljivo ravnovesje ekosistema. Medtem ko nekateri ta fenomen pripisujejo dolgotrajnejšim procesom v rangu geoloških dob, tj. ogromnim cikličnim podnebnim nihanjem čez več milijonov let, je večina še vedno mnenja, da so glavni razlogi za ta proces industrijske in kmetijske dejavnosti v zadnjih desetletjih in z njimi povezano sproščanje nepredstavljive količine toplogrednih plinov v ozračje. Le-to je posledica široke uporabe fosilnih virov kot vira energije, predvsem za proizvodnjo električne energije. Omejena razpoložljivost fosilnih virov in njihov vpliv na ekosistem sta med najpomembnejšimi dejavniki, ki zahtevajo gospodarstvo, ki temelji na uporabi obnovljive in čiste energije in lahko dolgoročno zagotovi jamstvo za trajnostno oskrbo. Posledica tega je, da je današnji elektroenergetski sistem podvržen precejšnjim spremembam, predvsem množični integraciji obnovljivih virov električne energije. Konvencionalne elektrarne (zlasti termoelektrarne) se ugašajo in nadomeščajo z decentraliziranimi, trajnostnimi in obnovljivimi viri energije, predvsem vetrnimi in sončnimi elektrarnami. Čeprav ta energetski prehod prinaša znatne koristi za okolje pa istočasno vodi tudi v večjo kompleksnost elektroenergetskega sistema, kar se odraža tako v nepoznanih odzivih in obnašanju elektroenergetskega sistema, kot tudi v novih operativnih izzivih pri njegovem vodenju. Električna energija je bolj kot kadarkoli prej sestavni del našega vsakdana, zato ima vsak njen dolgotrajnejši izpad precejšnje negativne socialne in ekonomske posledice. V tem kontekstu doktorsko delo delo obravnava spoznavnost elektroenergetskega sistema v realnem času ter preventivne in odzivne ukrepe za blažitev posledic izpadov električne energije pri odjemalcih. V prvem delu disertacije so na kratko predstavljena nastajajoča pametna omrežja s pripadajočimi izzivi in podana primerjava s klasičnim elektroenergetskim sistemom. V naslednjem poglavju sta opisana nadzorni sistem SCADA in trenutno najsodobnejša tehnologija sinhroniziranih meritev, ki jo omogočajo merilniki fazorjev. V tem poglavju so razloženi teoretično ozadje in glavne prednosti fazorjev, ter pomislek o njihovi pravilni uporabi v realnem sistemu. V naslednjem poglavju so podrobneje pojasnjene osnove enega od uporabljenih preventivnih zaščitnih ukrepov, povezanih s frekvenčno stabilnostjo EES, tj. podfrekvenčna razbremenitev, in predlagana nova shema za njegovo proženje. Učinkovitost sheme je preverjena s testiranjem strojne opreme v zanki, za uporabnost v realnem elektroenergetskem sistemu pa je nadgrajen tudi način njenega delovanja. Naslednje poglavje prikazuje pomen zaščite elektroenergetskega sistema in pojasnjuje potrebo po hitri lokalizaciji kratkih stikov. Poleg tega je prikazana nadgradnja algoritma za lokalizacijo kratkih stikov, ki poveča natančnost lokalizacije, hkrati pa določi tudi impedanco kratkega stika. Na koncu je predstavljen še okvir, potreben za uspešno implementacijo predlaganega algoritma v realnem okolju, ki nima na voljo namenske komunikacijske infrastrukture