Research on the Hybrid Energy Storage System Using a Superconducting Coil and a Secondary Battery

从补偿波动负荷和风力发电机、光伏电池等不稳定分布式发电产生的功率的角度出发，人们期待开发高能量密度和高功率密度的储能装置。超导磁储能（SMES，Superconducting Magnetic Energy Storage）比其他储能方法具有更高的功率密度，二次电池比SMES具有更高的能量密度。提出了采用超导储能系统和二次电池的混合储能装置作为高功率、高能量密度的储能方式，研究了各储能装置功率参考值的共享方法，并进行了实验和仿真。主要研究结果如下：1）针对系统的设计和评估，建立了二次电池和功率变换器的等效电路模型; 2）针对超导线圈和二次电池之间的功率共享，研究了高通滤波器和低通滤波器的方法。结果，由于较小的相位滞后，一阶高通和低通滤波器是优选的。由于滤波器的相位滞后，高阶滤波器的效果较差。3）采用上述带滤波器的模糊控制方法，避免了超导线圈的饱和和能量耗尽，并且可以进行二次电池的功率控制4）采用所提出的控制方法，对高速铁路变电站和光伏发电系统的波动补偿进行了仿真，测量数据。结果表明，混合储能系统在两种情况下均能达到较好的储能效果。但对于高速铁路变电站，由于超导磁储能系统补偿的频率范围内功率波动较大，因此取得了较好的效果。

Energy storage devices with high energy density as well as high power density are expected to be developed from the point of view of compensation of fluctuating load and generated power by unstable distributed generations such as wind turbines, photovoltaic cells and so on. SMES (Superconducting Magnetic Energy Storage) has higher power density than other energy storage methods, and secondary batteries have higher energy density than SMES. The hybrid energy storage device using SMES and secondary batteries is proposed as the energy storage method with higher power and energy density, the sharing method of power reference value for each storage device has been studied, and experiments as will as simulations have been carried out. Obtained results are summarized as follows.1) For the design and evaluation of the system, equivalent circuit models for a secondary battery and power converter have been developed.2) For sharing power between a superconducting coil and a secondary battery, the method using high pass and low pass filters has been studied. As a result, the first-order high pass and low pass filters are preferred due to smaller phase lag. Higher-order filters showed worse results due to phase lag of the filters.3) Using the method using fuzzy control with filter mentioned above, saturation and exhaustion of energy of superconducting coil have been avoided and power control of the secondary battery can be carried out4) Simulations of compensation of fluctuation from high speed railway substation and photo voltaic generation have been carried out by using developed control method and data from measurements. As a result, the effect of hybrid energy storage system has been verified for both cases. But the better result was obtained for the high speed railway substation, because of the higher fluctuating power at the frequency range compensated by SMES.