Microgrid flexibility and its ability to provide ancillary services to the transmission system operator

Tranzicijom energetskog sustava prema konceptu koji stavlja krajnjeg korisnika u centar postaje izuzetno važno razviti odgovarajuće optimizacijske i upravljačke modele novih subjekata u elektroenergetskom sustavu. Pri tome koncepti poput mikromreža, koji imaju mogućnost pružanja više usluga tržištu i operatorima sustava, su od izuzetnog značenja u budućim sustavima. Ovaj rad predlaže metodu definiranja vrijednosti pomoćne usluge koju mikromreža može pružati operatoru sustava ili pak krajnjem korisniku. U ovom slučaju mikromreža radi kao energetska zajednica koja je spojena paralelno ostatku sustava te je njezin rad definiran tržišnim signalima. Međutim, mikromreža također mora biti u stanju da se odvoji od ostatka mreže te održi stabilan rad u izvanmrežnom režimu rada. Stoga su u ovom diplomskom radu izrađena dva modela mikromreže: i) Mješoviti cjelobrojni linearni optimizacijski model koji određuje optimalne veličine jedinica unutar mikromreže za njen rad u otočnom režimu; ii) Dinamički model stabilizacije mikromreže pri prelasku u otočni rad. Granice dobivene iz ovih modela se koriste kako bi se dobila monetarna vrijednost pružanja usluge fleksibilnosti prema operatoru sustava.With the transition of electrical power systems towards a concept that puts end-user into the center, it becomes very important to develop suitable optimization and control models of the newly formed subjects in the system. Because of their ability to provide multiple services to the market and system operators, concepts like microgrids are of great significance to be the key element of the future systems. This paper proposes a method to define the value of emergency service which the microgrid can provide both to the system operator (SO) and its users. This means the microgrid operates as an energy community connected parallel to the rest of the system and its operation is driven by market signals. However, it also needs to be able to detach from the main grid and maintain stable operation in the off-grid regime. Therefore, this thesis contains 2 microgrid models: i) Mixed-integer linear programming (MILP) model which determines the optimal sizes of units within the microgrid for the operation of the proposed microgrid in the island mode; ii) Dynamical model of stabilizing the microgrid when going into island mode. The boundaries obtained from these models are used in order to determine the monetary value of providing flexibility to the distribution system operator (DSO)