モータ負荷のストール現象におけるトルク–速度曲線と安定限界線の等価性

抄録

Since it has become obvious that half or more electricity is used by induction motors, modeling of induction motor load has become regarded as essential in power system stability analyses even in Japan, because power system stability can be extremely spoiled by motor's stall phenomenon. Therefore, for understanding and explanation of motor's stall phenomenon, some theory has also become recognized as essential. The authors had demonstrated that motor's stall can be well explained by “torque-speed curve” considering impedance of power system side by analysis, simulation, and experiment. By the way, stall can be regarded as “fast voltage instability” making a pair with “slow voltage instability” caused by run-away of on-load tap changer. Since “slow voltage instability” has been well explained by “P-V curve”, it seems desirable that “fast voltage instability” (i.e. stall phenomenon) is also explained by “P-V curve”. In P-V curve for explaining motor's stall, it becomes an issue how mechanical output torque that depends on only motor speed can be considered. On one hand, T-ω curve can be successfully translated onto P-V plane. On the other hand, “stability boundary curve” is introduced from past studies. These two theories, which seem different at a glance, are demonstrated as equivalent and well agree with simulation result.