Dynamic equivalents of power stations for optimal control of power system security

In order to obtain a fast and optimal control scheme of power system security, dispatchers usually use the detailed representation of the study system and dynamic equivalents of the external system for dynamic security analysis. This paper presents a time-domain aggregation method using structure constraints for dynamic aggregation of generating units/power stations. All generating unit components are aggregated so as to obtain a corresponding equivalent model having a desired structure of coefficient matrices in a time-domain representation. The equivalent parameters are identified by the structure preservation of coefficient matrices. In this way the equivalent models of power stations in the external system can directly be used for the dynamic security analysis of the study system. As a result a fast and optimal control scheme of the system can be carried out efficiently. The proposed method is one of the key steps in constructing the optimal control scheme of power system security. The corresponding program is validated on a sample power system