| Tidal energy is a kind of renewable and clean energy with huge potentiality to exploit.But the tidal power turbine of fixed speed operates in non-optimal conditions for most of the time,because the head changes periodically with large amplitude as the tide fluctuates,resulting in the problems of low operation efficiency,exacerbated vibration and cavitation,which impede the development of tidal power plant.Therefore,this paper proposes the variable speed permanent magnet synchronous tidal power unit with full-scale converter,which keeps itself operating in optimal condition by adjusting the speed as head changes,and then researches the following problems:the variable speed operation optimal characteristics of unit,parameter stability region and optimal parameter tuning of speed governing system,the change of power generation.The details are as follows:(1)Firstly,the variable speed operation optimal characteristics is obtained based on the turbine model synthetic characteristic curves,on this basis,the calculation method of optimal speed of each head and power is determined,which provides a reference for the control of variable speed unit.Secondly,the blade combination relationship method proposed for variable speed turbine overcomes the problems of numerous measurement quantities and complicated interpolation of traditional method.Thirdly,taking the JiangXia power plant 3#unit as an example,the efficiency change of turbine operates at variable speed is analyzed,concluded that the efficiency can be increased by a maximum of 23.39%at forward and 33.55%at reverse,which reveals that variable speed operation can improve operation efficiency and ameliorate operation conditions;besides,the maximum power change of unit operates at variable speed of each head is analyzed,the result shows that variable speed operation can increase the maximum power of low head,and the lower the head is,the more the power increases.(2)The speed governing system mathematical model of variable speed permanent magnet synchronous tidal power unit with full-scale converter is established,and the stability region is given according to the Hurwitz criterion,on this basis,the influence of controlling objects parameters on the stability region is analyzed,which provides a reference range for the tuning of regulating parameters.(3)The optimal functional relationship between regulating parameters and controlling objects parameters of variable speed permanent magnet synchronous hydro power unit speed governing system with certain synthetical dominant pole is established by using the synthetical dominant pole-placement method,the optimal parameter tuning equation is determined combined with the orthogonal experiment,and then,the tuning equation is verified to be true by simulation analysis,which provides a reference for the regulating parameters configuration of variable speed unit.(4)The power generation change of JiangXia power plant 3#unit operates at variable speed is calculated during a typical tidal cycle,the results show that the power generation can be increased by about 3.65%,of which the power generation is increased by 0.97%and the generation time is extended by 3 min at forward,the power generation is increased by 10.40%and the generation time is extended by 8 min at reverse,revealing that the tidal power unit operates at variable speed can extend generation time and increase power generation,and it is an effective way to improve the generation benefits of unit. |
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