長距離くし形系統における内部共振の検証

抄録

Mid and Western area 60Hz system of Japan forms a typical longitudinal power system. A weakly-damped low-frequency oscillation mode exists. There is a possibility that autoparametric resonance occurs for large disturbances like system faults because of interactions among oscillation modes. In this paper, we confirm the autoparametric resonance with a large simulator called APSA. The simulator accurately models generators and transmission lines. The confirmation is important to show the existence of the autoparametric resonance. First, we observe with the simulator that generator swings decay for short faults while they diverge for long faults. It is difficult to verify that this phenomenon is the autoparametric resonance with swing curves only. As its aids, we use eigenvalue analyses and digital simulations. We identify oscillation modes contained in the swing curves to extract two main oscillation modes. Then, we show that the force applied on the low-frequency oscillation mode draws the same trace as that of the autoparametric resonance under the action of the other mode. This proves that the phenomenon observed with the simulator is truly the autoparametric resonance. Lastly, we execute simulations under various system conditions, and show the autoparametric resonance occurs under normal conditions.