Self-adapting Variable-frequency Tmd Technology And Its Application To The Vibration Reduction Of Offshore Wind Power Tower

With the excessive consumption of the routine energy, the problems of energy crisis and pollution has become prominently. The demand for clean and renewable energy is more and more urgent due to the energy saving and environment protection. As a kind of clean and renewable energy, wind power has gained more and more attentions because of the rich resources and little impact on environment. The new trend of wind power is to use the offshore wind power generation.As a high-rise structure,the offshore wind power generation tower has a large height-width ratio and a relatively flexible flexural rigidity, it can easily cause vibration under the horizontal load (especially the wind load), leading to structural fatigue and destruction, and pose a threat to the safety of the structure. Using the vibration control method to restrain the tower vibration is an important aspect of the offshore wind power generation study.Different from the ordinary structural vibration reduction, the core problem of the high-rise structure vibration control is to adopt a control device to impose the control force to suppress the dynamic response under the structural vibration control theory by changing the traditional train of thought that enhance load-bearing structure to resist wind-induced vibration or earthquake. Among the passive control methods, TMD and MTMD are two of the most common methods and have the most practical and engineering applications.Due to the impact of the wind level, the offshore wind power generation tower will adjust its own state to protect the structure safety, making the natural frequency of the structure change. Because of the singleness of frequency control, the traditional TMD method obviously does not meet the vibration reduction requirements of the multi-frequency structure. Though MTMD can achieve to control the multi-frequency, it still has some disadvantages, such as the huge structure, complicated installation and interference with vibration control generated by non-working parts.Based on the results of previous studies, the concept of "Self-adapting Variable- Frequency TMD" is suggested by considering the vibration control requirements of multi-frequency structure under the special circumstances in this paper. The Self-adapting TMD not only retains the advantages of multi-frequency of MTMD, but also is a single TMD system with the advantages of simple installation and maintenance. The principle of the Self-adapting frequency TMD system is discussed in detail and the key problem of this system is also studied in this paper. Specific studies are as follows:1. Based on the research of Structural vibration control technology before, the concept of "Self-adapting Variable- Frequency TMD" is suggested drawing on the advantages of TMD and MTMD. This new device is able to overcome the singleness of traditional TMD control frequency, and is applicable to the vibration control of the multi-frequency structure through Tuning its frequency to suit for structure.2. The working principle details of the new device is expounded,while the feasibility is also studied in this paper through numerical simulation and physical modeling experiments. The results show that, The new method can overcome the limitations of the existing TMD, and is applicable to the vibration control of the multi-frequency structure.3. Take the tower of offshore wind power generation system for example, the vibration states of the tower before and after the installation of Self-adapting frequency TMD are simulated with Finite element software to verify the effect of Self-adapting Variable- Frequency TMD.The results show that as a further improvement of the traditional MTMD, the Self-adapting variable-frequency TMD vibration control device not only maintains the advantages of MTMD that has a number of operating frequency, but also has its own unique. The Self-adapting variable-frequency TMD vibration control device can be applied widely with widespread application of flexible structures such as high-rise buildings and structures, bridges and so on.