소형 수직축 풍력터빈에 대한 동특성 분석 및 동적모델 수정

Abstract

The dynamic characteristics including natural frequencies and excitation frequencies were evaluated for a small 10 kW vertical axis wind turbine for investigating the root cause of excessive vibration of a structure under 30RPM of rotor speed. Acceleration responses were measured at 12 distributed locations for ambient vibration tests during non-operational and operational conditions. The natural frequencies for the lowest 2 bending modes were estimated and the excitation frequencies, i.e. 1P, 2P, 4P, were also estimated according to the rotational speed using the responses under operational conditions (i.e. power generation condition). It was verified that the excessive vibration was due to the resonance between the 4P excitation and the 1st vibration modes. To resolve the resonance issue, dynamic model modification was carried out and concrete filling inside the steel tower up to 7 m height was the most efficient way to increase the 1st natural frequency about 20% by numerical simulation. After the concrete filling, the acceleration responses were measured again and it was observed that the 1st natural frequency was increased as amount of 21% by concrete filling.