Original scientific paper This paper presents an improved model of multi-DGs system for enhancing the stability. The distributed generations (DGs) in the system are equipped with the additional active power controller as the technique of enhancing the wind-thermal-bundled system stability. Firstly, the influence of multi-DGs system on the oscillation of the system is analysed. Then, the conditions for DGs producing positive damping to the power system are obtained. Secondly, taking the wind farm as the study object, the increment of the frequency of the point of common coupling (PCC) in the wind farm is feedback to the active control loops for regulating the active power of wind turbine. At the same time, the multi-DGs system holds a positive damping effect on the power system which enables the dynamic behaviour of the wind farm to be improved. Thirdly, the effect of time delay on control performance is further considered and two propositions for solving critical time-delay are put forward and proved, which are used as the constraint condition of additional active power control. Finally, the time domain simulation is implemented and the correctness of the proposed method is verified by the root locus analysis and frequency domain simulation. The results show that the additional active power control can significantly enhance the power system damping. However, the wind farm will provide negative damping and even the whole system will not maintain the power angle stability when the time-delay increases and exceeds the critical time-delay.
Keywords: anti-islanding; critical time-delay; multi-DGs system; power system damping; wind farm
Istraživanje stabilnosti Multi-DGs sustavaIzvorni znanstveni članak U radu se daje poboljšani model multi-DGs sustava za poboljšanje stabilnosti. Distribuirana proizvodnja (DGs) u sustavu opremljena je dodatnim regulatorom snage kao metodom za poboljšanje stabilnosti vjetro-toplinskog višežilnog sustava. Najprije se analizira utjecaj multi-DGs sustava na oscilacije sustava. Tada se postižu uvjeti da DGs stvaraju pozitivno prigušenje energetskog sustava. Zatim, uzmajući vjetroelektranu za predmet istraživanja, porast frekvencije točke zajedničkog spajanja (PCC) u vjetroelektrani je povratna informacija za aktivne upravljčke petlje za reguliranje aktivne snage vjetroturbine. U isto vrijeme multi-DGs sustav zadržava pozitivan učinak prigušenja na energetski sustav koji omogućuje poboljšanje dinamičkog ponašanja vjetroelektrane. Kao treće, razmatra se učinak vremenskog kašnjenja na funkcioniranje sustava upravljanja te se razmatraju i dokazuju dva prijedloga za rješenje vremenskog zastoja, smatrajući ih ograničenjem za dodatno aktivno upravljanje snagom. Konačno, implimentira se simulacija vremenskog područja i provjerava se točnost predložene metode pomoću root locus analize i simulacije vremenskog područja. Rezultati pokazuju da dodatni regulator snage može značajno poboljšati prigušenje energetskog sustava. Ipak, vjetroelektrana će imati negativno prigušenje i cijeli sustav čak ne će od...