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为了验证基于SSOGI-RLSMC联合算法在纹波抑制方面具有更高的纹波检测精度和补偿精度、更快的响应速度,本文在MATLAB/Simulink搭建如图1所示的系统模型进行仿真分析。鉴于对电源输出的纹波进行快速傅里叶变换(Fast Fourier Transform,FFT)分析后发现实际纹波主要是以50, 100, 150 Hz为主的低频成分,因此利用表1中系统参数,并设置式(11)纹波电流源对整个DCAPF系统进行仿真验证。
参数 说明 参数值 DC 直流 100 A ${R_{\rm{L}}}/{L_{\rm{L}}}$ 非线性负载 0.5 Ω/4 mH L 滤波电感 1 mH R 等效电阻 1 Ω Cf 直流侧电容 1 mF Lf 直流侧电感 0.1 mH -
图8为采用三种纹波提取方式得到的谐波分量。
从图8中可以看出,改进电流平均值法需要20 ms得到较准确的纹波,电源纹波系数为10-4,而传统的低通滤波器需要50 ms延时才能得到检测结果,电源纹波系数为10-4,本文采取的SSOGI纹波检测方法只需10 ms即可分离出纹波,电源纹波系数为10-5,速度最快,延时最小,而且提高了纹波检测精度。
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图9为未投入DCAPF时的电流波形与频谱分析。
由图9可知,在DCAPF补偿前THD为1.06%,其主要为50、100、150等低频纹波含量较高。
图10在仿真时间0.1 s时投入DCAPF,通过传统的PI对DCAPF控制。理论上DCAPF可以抵消检测到的纹波,进而获得直流分量。通过图10可以看到,负载电流很快补偿到直流200 A,经过计算,此时电源纹波系数达到10–4,电流纹波相对于直流的THD为0.12%。
图11为基于趋近律滑模控制的控制策略加入DCAPF中所得到的负载电流波形及频谱分析图,由于趋近律滑模控制的加入,使得RLSMC控制器能够快速对指令电流的变化做出响应,体现较强的跟踪能力, 纹波指令电流的跟踪性能明显改善, 利用纹波电流的计算公式对检测到的纹波电流计算其纹波系数, 最终得到电源纹波系数达到10–5,电流纹波相对于直流的THD为0.10%。图10(a)和图11(a)中圆圈所标记的为负载突变阶段,从图中可以看出,负载突变后,经过趋近律滑模控制的电流纹波的THD由0.99%降至0.64%,通过搭建的仿真模型进行仿真,可以看出趋近律滑模控制算法实现了纹波电流的精确跟踪与补偿,并且在负载突变的情况下,趋近律滑模控制策略具有更优越的动态跟踪和补偿性能。
Accelerator Power Ripple Suppression Based on SSOGI-RLSMC Combined Algorithm
doi: 10.11804/NuclPhysRev.38.2020042
- Received Date: 2020-06-22
- Rev Recd Date: 2020-08-02
- Publish Date: 2021-03-20
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Key words:
- ripple detection /
- parallel second order generalized integrator /
- approach law sliding mode control /
- DC active power filter /
- ripple suppressio
Abstract: The power supply system of heavy ion accelerator requires high stability and ripple precision of excitation power supply. Because of the existence of magnet load, the ripple has an impact on the precise control of particle trajectory by magnetic field. To solve the above problems, a new combined algorithm based on SSOGI-RLSMC is proposed to reduce the output current ripple of excitation power supply under the influence of magnet load and improve the current stability. The new joint algorithm extracts the ripple component quickly and accurately by using the parallel Second-Order Generalized Integrator(SSOGI) as the ripple detector, and obtains the command current with high precision. The error signal is obtained by subtracting the command current and the compensation current of the DC active power filter, and the Reaching Law Sliding Mode Control(RLSMC) algorithm is used to track and compensate the error signal dynamically, so as to improve the direct current active power filter can suppress the ripple of the output current of the excitation power supply, so as to achieve the precise control of the particle trajectory. Finally, through MATLAB/Simulink simulation, it is proved that the new joint algorithm can effectively improve the accuracy and stability of the output current of the excitation power supply, and improve the ripple current suppression ability of the DC active power filter.
Citation: | Xinhua YANG, Yongqiang WANG, Jiqiang LI, Yuan CUI, Daqing GAO, Yue ZHENG. Accelerator Power Ripple Suppression Based on SSOGI-RLSMC Combined Algorithm[J]. Nuclear Physics Review, 2021, 38(1): 45-51. doi: 10.11804/NuclPhysRev.38.2020042 |