Study of Power System Online Dynamic Equivalent Based on Wide Area Measurement System

Dynamic equivalent can largely reduce the calculation amount for cross-area interconnected power systems. It is fundamental work and an effective approach for dynamic analysis of large power systems. Online dynamic security analysis needs real-time calculation of dynamic equivalents. Wide area measurement system supplies a good support for realizing possible real time dynamic equivalent. One way is based on coherency equivalent theory and to use plenty of history data from measurements to obtain coherency information of generators offline and match the dynamic equivalents through real-time measurements. The other way is based on parameter and model identification. A dynamic equivalent model of a parallel of equivalent generator and load was put forward. The identifiability of equivalent model and the identification algorithm of parameters were briefly discussed. Test on EPRI 8-machine 36-bus system shows that dynamic equivalent model of external system can reflect the dynamic behaviors of the original system accurately.