Clustered Effective Reactive Reserve to Secure Dynamic Voltage Stability in Power System Operation

Reactive power reserves are important for grid stability and have a variety patterns depending on fault location as power systems become larger and complex. This paper presents the clustered effective reactive reserve (CEQR), an indicator that is suitable for identifying the risk of dynamic voltage stabitlity in terms of power system operation. This indicator provides the following features: i) It calculate the local realistic reactive reserve to recognize dynamically changing system conditions; ii)it derive clustered areas to identify valid regions for system control. The proposed method uses the sensitivity between dynamic reactive resources or load buses and a particular bus to obtain the correlation. And since this indicator is calculated using only the system topology, current and maximum outputs of the generators, there is less computational burden. This study verified the features of clustered effective reactive reserve (CEQR) by analyzing the practicable dynamic voltage collapse scenarios in the Korean electric power (KEPCO) system. In addition, as a countermeasure against the dynamic voltage collapse, the control performance of blocking tap changer scheme using the proposed indicator is described.