The Influence of High-penetration Pumped Storage Units Working in Different Operating Modes on the Transient Angle Stability

Different operating modes of pumped storage unit (PSU) will influence the transient angle stability (TAS) of the system differently. However, the existing TAS analysis method mainly focuses on the TAS considering just a single operating mode of the PSU, which lacks the transverse comparison ability of analyzing the difference among various operating modes. Therefore, based on equal area criterion (EAC), a TAS analysis methodology which is suitable for assessing the TSA margin (TASM) of the system with high-penetration PSUs working in different modes is proposed. For the first, the dynamic characteristics of the PSU is analyzed, and the equivalent circuit (EC) is obtained. Then, the EC of the whole system is constructed by combining the obtained EC of the PSU with the EC of the other components in the system. Further, by analyzing the changes of the electromagnetic power before and after fault occurrence, calculating the acceleration area (ACA) and the deceleration area (DCA), and then the TASM is obtained to reflect the influence of the PSU working in different modes on the TAS of the system. Finally, the effectiveness of the proposed method is verified via an example from the actual regional power system in China. Moreover, an optimization of finding the critical power shedding of the generators when the PSU works in the different operating modes is also carried out to develop emergency control strategy.