No abstract

As one of the most important ancillary services, reactive power production plays a crucial rule in power system operation, reliability and security. Because of the opportunity costs in providing reactive power, producers are under great pressure to provide VAr support. In this paper, a new challenge on the reactive capability curves (RCC) of the synchronous generator is discussed. The RCC is a graphical representation of the reactive and active power produced by the generators under various operating conditions, as specified by the cold gas pressure and temperature inside the generators as well as the power factor. These curves define the normal limits of operation without exceeding thermal limitations. The generator manufactures provide the determined RCC, However, in the real world RCC is changed over time and aging of the generators. This paper discusses about some reasons, which lead to the variations, and the importance of re-evaluation of RCC.