-
可调光阑已经用在ADS加速器样机上调节束流强度[10],该加速器样机使用的控制系统为基于EPICS (Experimental Physics and Industrial Control System) 软件的加速器控制系统。 为了满足CiADS 耦合控制的需求,本工作需要在高可靠性的分布式控制系统(Distributed Control System, DCS)中实现用可调光阑调节束流强度的功能,该DCS系统将用于反应堆的控制。本文与文献[11] 使用的是同一套DCS控制系统, 由北京广利核公司生产,该公司的产品已经用在我国多个核电站反应堆控制里。我们使用的这套DCS控制系统包括操作站、控制站、通讯网络和服务器等,DCS控制系统通过控制站里的网关与第三方产品 (例如:本文的可调光阑及其电机) 通讯。
图7显示了束流强度调节功能在DCS系统上实施的控制框图。左下角显示了测量束流强度的三种探测器:直流变压器(DCCT)、交流变压器(ACCT)和法拉第筒(FC),束流强度探测信号经过网关1进入DCS系统控制站。然后,控制站的控制器进行束流强度调节所需的信号处理、控制算法和逻辑分析等。PID控制器通过比较束流强度设定值I0和测量值I,根据比例系数Kp、积分系数Ki 和微分系数Kd三个参数来产生控制动作U2。其中,U2为自动调节光阑需要转动的角度。DCS系统中还设定了手动调节功能,当操作员在操作站里按动手动调节键时,光阑转动角度U为手动设定值U1。最后,光阑转动角度U通过控制站里的网关输出给外部的光阑驱动系统。
图8显示了DCS系统实现束流强度控制的测试图,图的左侧为DCS控制系统的机柜,是垂直放置在地面上的;图8的右侧为可调光阑、电机及其控制器等,它们水平放置在桌面上,都是由倍福公司生产。DCS系统里的网关通过网线连接到倍福控制器CX2020。倍福控制器再连接至倍福驱动器AX5203及其伺服电机AM8032。
在完成DCS系统和一整套倍福的运动控制系统联调后,利用手动调节进行了光阑转角的精度测试。如图7中的控制框图所示,手动设定光阑角度值N0,比较光阑目前的角度值N。如果两者不一样,DCS系统通过网关2将角度调节值送给电机驱动器和控制器,同时,电机驱动器和控制器又将新的角度测量值N通过网关2送回到DCS系统并显示在操作站。角度测量中对正向转动和反向转动的各种实例进行了测试,例如:第一次从0°正向转到180°,再反向转回到0°。第二次则从0°正向转到90°,再反向转回到0°;然后,从90°正向转到180°,再反向转回到90°;以此类推。表1列出了光阑角度定位偏差测量值,测量结果表明光阑转角精度0.002°。在测量中观察到:光阑转角精度只与光阑角度设定值有关,而且,每一次测量的结果都一样。光阑转角精度只与光阑的制作工艺有关,与DCS系统的数据传输及其测量方法无关。
正向定位测试 反向定位测试 光阑角度设定
定位点/(°)光阑角度测试
定位点/(°)光阑角度定位
平均偏差/(°)光阑角度设定
定位点/(°)光阑角度测试
定位点/(°)光阑角度定位
平均偏差/(°)0 0.000 00 0.000 00 195 195.000 00 0.000 00 15 14.999 60 0.000 40 180 179.999 78 0.000 22 30 30.000 40 −0.000 40 165 165.002 60 −0.002 60 45 45.000 00 0.000 00 150 150.001 14 −0.001 14 60 59.999 60 0.000 40 135 135.000 88 −0.000 88 75 74.998 40 0.001 60 120 120.001 50 −0.001 50 90 90.016 72 −0.016 72 105 105.001 36 −0.001 36 105 105.000 90 −0.000 90 90 89.999 78 0.000 22 120 119.999 50 0.000 50 75 75.000 40 −0.000 40 135 134.998 02 0.001 98 60 59.999 38 0.000 62 150 149.998 06 0.001 94 45 45.001 32 −0.001 32 165 164.999 30 0.000 70 30 30.000 16 −0.000 16 180 180.000 66 −0.000 66 15 14.999 82 0.000 18 195 194.998 06 0.001 94 0 0.000 00 0.000 00 第2节中图5显示了束流FWHM为10 mm时,束流强度与光阑角度的对应关系,根据测量结果得到了束流强度的调节精度。当最大束流强度为2 mA时,光阑角度设定值分别为0°, 15°, 30°, 45°, 60°, 75°, 90°时,正向转动的精度为0, 0.01, 0.01, 0, 0.012 5, 0.02, 0.1 μA;反向转动的精度为0, 0.004 5, 0.004, 0.033, 0.019 4, 0.005, 0.001 4 μA。因此,正向反向转动光阑角度,束流强度的调节偏差小于0.1 μA。调节束流强度的精度达到0.000 05 A,例如:当束流强度为1 mA时,束流强度的调节偏差小于0.05 μA。该束流强度调节精度足够满足CiADS装置的需要。从图5可见,光阑角度超过90°时,束流强度变化很小。即使光阑角度调节有微小的偏差,束流强度调节也是非常准确的。
Study of Beam Intensity Control for CiADS Facility Based on Genetic PID Algorithm and Its Implementation in DCS Control System
doi: 10.11804/NuclPhysRev.40.2022085
- Received Date: 2022-08-01
- Rev Recd Date: 2022-09-16
- Publish Date: 2023-09-20
-
Key words:
- accelerator driven sub-critical system /
- beam intensity /
- proportion-integral-differential control /
- distributed control system.
Abstract: In an accelerator driven sub-critical system(ADS), it is very important to automatically control the beam intensity of the accelerator. The method for controlling the beam intensity with a proportion-integral-differential(PID) controller has been studied for the China initiative Accelerator Driven System(CiADS) facility. Firstly, in order to quickly find the global optimal parameters of the PID controller, Genetic Algorithm is used for determining the parameters of the PID controller, where the method for initializing the population in the algorithm has been improved. Secondly, a model of beam intensity is built by considering the proton beam with a Gaussian distribution of a given FWHM(Full Width at Half Maximum) at the Low Energy Beam Transport(LEBT) line of the accelerator, in order to evaluate the proposed control method with the extracted PID parameters. The simulations based on the model of beam intensity have indicated that the beam intensity varies with either the different value of FWHM or the different position of beam center. Thirdly, both the automatic and manual control functions for the beam intensity have been implemented in a distributed control system(DCS) system. In the automatic control function, the measured value of the beam intensity is sent to the DCS system and is compared with the setting value. Then, the new values of the aperture size and the rotation angle of the aperture are calculated with the PID controller and are used to adjust the beam intensity. Finally, the accuracy of the rotation angle of the aperture is measured by using the manual function in the DCS system. The measurement results show that the deviation of the angle adjustment of the aperture is less than 0.002 degree, and the adjustment accuracy of the beam intensity is 0.000 05 A.
Citation: | Shiwu DANG, Xinxin LI, Wenjuan CUI, Wenjing MA, Detai ZHOU, Zhiyong HE, Kai YIN, Ruifeng GU, Haihua NIU. Study of Beam Intensity Control for CiADS Facility Based on Genetic PID Algorithm and Its Implementation in DCS Control System[J]. Nuclear Physics Review, 2023, 40(3): 472-477. doi: 10.11804/NuclPhysRev.40.2022085 |