Dynamic equivalent modeling of large power systems using structure preservation technique

This paper presents an aggregation method to build a coherency-based dynamic equivalent of detailed generating units models and their control systems. The proposed method is based on the preservation of the coefficients matrices structure in the time domain representation. According to the principle of structure preservation, the parameters of the equivalent generator and its control systems are calculated directly. This procedure requires much less computation effort and is suitable for online studies compared to other methods, which use mainly the iterative process in frequency domain to derive equivalent parameters. For validation purposes, this aggregation method is applied to group an area of eight generators inside a test system of 16 generators and 68 buses. Results show that the reduced system retains the dynamic performance of the original system with good accuracy, and all inter-area modes of the original system are preserved in the reduced system.