GENERALIZING THE APPROACH TO FACTS DEVICE MODELLING IN STEADY STATE ANALYSIS OF ELECTRIC POWER SYSTEMS

This thesis presents a new method for modelling power flow controlling devices in steady state analysis of the electric power system. The developed method succeeds in establishing the modelling problem externally with respect to an underlying load flow routine. In the formulation of the presented method, the variables that represent the power flow controlling devices are found among the common load flow programmes. Meanwhile, the equations that describe the devices are encapsulated in their own criterion vector function which is constructed separately from the underlying load flow routine and has the trait of becoming zero when the question of modelling controllable devices is correctly answered. With this, the steady state analysis of these devices is reduced to finding the values of load flow input data that set all the elements in the external criterion vector function to zero. Modelling the power flow controlling devices is thus reduced to a multidimensional root-search problem. To find the root, the Newton method is used due to its good convergence characteristics. At each iteration of the Newton root-search, a full load flow calculation is ran using a standard program. Apart from having Newtonian convergence characteristics the advantage of the method is its external character, which enables one to model the controllable devices without altering the load flow program. This makes the method applicable to any load flow program using any type of algorithm. Furthermore, expanding functionality in terms of adding devices or adding control modes to existing devices requires no alteration to the underlying load flow routine.V disertaciji je predstavljena nova metoda za modeliranje regulabilnih naprav v stacionarni analizi elektroenergetskega sistema. Posebnost razvite metode je v tem, da uspe problem opisa regulabilnih naprav formulirati v celoti eksterno glede na podrejen program za izračun pretokov moči. Regulabilne naprave se pri razviti metodi opiše z veličinami, ki jih najdemo med vhodnimi podatki izračuna pretokov moči, enačbe, ki odgovarjajo delovanju teh naprav, pa so zajete v svoji kriterijski funkciji, ki je konstruirana eksterno glede na podrejeni izračun pretokov moči. Ta kriterijska funkcija ima to lastnost, da je njena vrednost enaka nič, ko so regulabilne naprave pravilno modelirane. Problem analize stacionarnega stanja regulabilnih naprav se tako reducira na iskanje tistih vrednosti vhodnih podatkov izračuna pretokov moči, ki postavijo vse elemente kriterijske funkcije na vrednost nič. Za iskanje ničle kriterijske funkcije je z namenom zagotavljanja hitre konvergence uporabljena Newtonova iterativna metoda. V vsaki iteraciji izračuna pri razviti metodi se kot podrejena rutina zažene izračun pretokov moči s klasičnim programom. Poleg dobre, Newtonske konvergentnosti je prednost razvite metode v njenem eksternem značaju, ki nam omogoča modeliranje regulabilnih naprav ne da bi pri tem spreminjali program za izračun pretokov moči. Zaradi te lastnosti je metoda po eni strani kompatibilna s katerimkoli algoritmom za izračune pretokov moči, po drugi strani pa dodajanje novih regulabilnih naprav oz. dodajanje novih regulacijskih zmožnosti na obstoječe regulabilne naprave ne zahteva spreminjanja kode osnovnega programa za izračune pretokov moči