Study on PCS7 Heavy Plate Feeder automation control system

Transcription

1 Journal of Engneerng Mechancs and Machnery (2016) 1: Clausus Scentfc Press, Canada Study on PCS7 Heavy Plate Feeder automaton control system Cheng Longquan Schuan Electromechancal Insttute of Vocaton and Technology, Panzhhua, Schuan, Chna, Keywords: PCS7; Heavy Plate Feeder; Automatc Control System; Study Abstract: Amng at problems n the secondary crushng system of a concentrator crushng plant, such as the old-fashoned control mode of heavy plate feeder control system, overload and under-load condtons of the mechancal equpment, large labor ntensty of the operators, control lag, and low producton effcency, the research s done on automaton desgn of heavy plate feeder n the secondary crushng system of the crushng plant. The proposed method s to adopt PCS7 system to make automatc detecton, control the start-stop and the speed of SIEMENS converter whch s used to drve the heavy plate feeder, and use WINCC to desgn the montorng pcture of the secondary crushng system. The research shows that, wth automatc control based on WINCC and PLC, the system becomes flexble, convenent, and stable, and the overload and under-load condtons are elmnated, whch further results n lower falure rates. In practcal applcaton, through contnuous optmzaton of the mproved automatc control system of the heavy plate feeder, better performance on stablty, accuracy and falure rates s obtaned. 1. Introducton In the crushng plant, large peces of vanadum-ttanum magnette ores from the stope are crushed nto standard 12mm ores by the feedng system and crushers, wth three-stage procedures of prmary crushng--secondary crushng--fne crushng. These crushed ores are then nput nto the ball mll of the grndng plant. Throughout the whole crushng process, the secondary crushng system plays a vtal role, where SIEMENS converter drve 440 s employed n the heavy plate feeder of the ground ore bn to feed the secondary crushng system, sevng system and fne crushng system. The ore feed has an drect affect on the effcency, energy consumpton and system yeld. The operator operates the potentometer on the operaton box to adjust the converter operatng speed, whch further controls the feedng speed(ore quantty). Several shortcomngs exst n the actual producton process: Frstly, the operator needs to operate the heavy plate feeder located n the 5 meter deep underground adt, that could leads to hgh labor ntensty. What s worse, the operator s requred to use fxed-lne to confrm whether the ore nput to the next procedure meets requrements, so that the operatng speed of the feeder can be adjusted accordngly. To bascally ft n wth the need of producton need, at least sx tmes confrmaton and adjustments n one hour are needed, whch apparently brngs heavy burden on the operator and leads to low productvty. Secondly, equpment under overload or under-load condton ncrease producton costs. For example, facng wth the badly damaged drve dsk assembles of overload crushers, a whoopng 60 mllon RMB s spent on mantenance spare parts. In the meantme, 19

2 under-load condton ncreases the energy consumpton of crushers, as klowatt-hour more on electrcty wth total prce of 30,000 RMB s spent. Thrdly, the workng effcency s far more satsfactory, falng to feed stably, precsely and n tme, equpment such as crushers can only acheve a capacty of about 520t/h, falng to reach the desgned 700t/h. Low effcency have a heavy nfluence on ore yeld. To solve the above-mentoned ssues, mprovement on the legacy control system of the heavy plate feeder n crushng plant s dscussed n ths paper. 2. The Secondary Crushng Process Through the belt transmsson system, ores n the ground bn are transported to the feeder and then the crusher, where the crushed ores are seved nto the sevng bn. Fg 1 llustrates the whole crushng process. Ore bn Heavy plate feeder Belt transmsson Crusher Sevng bn Belt transmsson Fg 1. Flow Chart of secondary crushng process 3. Control System Our mproved control system adopt closed-loop cascade controllng archtecture, ncludng feedng control loop and load control loop. The control prncple s shown n Fg 2. Interference PID Sampled regulator Converter feeder Ball mll Electrcal ear sensor Electrcal belt wegher Fg 2. Feedng control system schematc dagram The nner loop archves constant feed control, whle the cascade part archves load control. An electronc belt wegher detects the ore feed, under the measurement and control of feedng control loop, the feeder rotaton speed s governed by the converter n order to adjust the ore feed quantty. Sad process ensures that the feed quantty be constantly adjusted when the feed set-pont keeps the same. Durng the control, the control perod T s equal or greater than the latency t. In addton, the PI algorthm s used for floatng purpose. Integral separaton s appled to optmze the PI algorthm, to decrease the overshoot and shorten adjustment tme of the control system. When the error s mnmzed to a certan range, sad ntegral tem can only be effectve [1]. 20

3 The model algorthm s shown as follows: u K ( e K p T T j j 0 Td e ) T K 1( e j K 0( e j ) ) K P s the proporton coeffcent, I s the crtcal devaton, T s the ntegral tme, K s the separaton coeffcent, e e j s the devaton between the ore feed and the actual ore quantty [2]. Based on the SIEMENS converter drve 440 bult-n seral communcaton nterface(sci), PROFIBUS cable s used to connect the 9 th slave staton ET200M of the orgnal PROFIBUS-DP feld bus seral dstrbuted system to the converter, to make the MM440 converter the 10 th slave staton [3]. When WINNC has bult connecton wth S7-400PLC through the Ethernet, and S7-400PLC has bult connecton wth 440 converter through PROFBUS-DP, WINNC s able to montor the varables n S7-400PLC programs. And then S7-400PLC can supervse the PZD zone of the MM440 converter, to acheve remote control on the start-stop and speed gvng of the converter [4]. The system structure s shown n Fg 3. Wncc Swtch Ethernet Profbus-DP S7-400PLC (3-9) ET200M MM440 Fg 3. System structure 4. Hook between MM4400 Converter and PROFIBUS-DP, Parameter Confguraton 4.1 Converter Installaton SIMENS converter 440 s chosen, who has superorty n overload ablty under low-speed, hgh-torque output load condton and good dynamc performance [5]. Insert the DP communcaton model matchng wth the MM440 converter nto the SCI. One end of the SIMENS DP bus cable (6XV1830-0EH10) s connected wth the DP bus connector of the 9 th slave staton ET200M, and the termnal resstance s swtched from On to Off, meanwhle, the other cable end s connected to the DP communcaton model to communcate wth the converter through ts SCI [6]. 4.2 Hardware Confguraton, Hook between Converter and DP network Hardware confguraton s establshed on a upper computer nstallng SIMENS Step7 programmng software [7], as shown n Fg4. Hook between Converter and DP network s llustrated n Fg 5. Save and comple the hardware confguraton and download t to S7-400PC. 21

4 Fg 4 Hardware Confguraton Fg 5.Hook between Converter and DP network 4.3 Parameter Confguraton of converter 440 To acheve DP bus communcaton, the parameter of converter 440 should be confgured: P0003: Access confguraton: before the DP communcaton parameter s set, the P0003 parameter s set to 3-expert level, and then t s permtted to confgure the DP network parameters, when t s fnsh, the P0003 parameter s modfed to 1-standard level. P0700 Select dgtal command sgnal source: the communcaton board(cb) s set to 6-com lnk, to make communcaton avalable. P0719 Command, frequency set-pont Confguraton: the parameter s set to zero, the command controller swtch s used to select converter control command source, and swtch between programmable BICO parameters and fxed command/set-pont, between command source and set-pont sgnal source. P0918 CB Address Confguraton: Assgn the converter s bus address on PROFIBUS-DP to CB. Two possble ways can be appled to set the bus address, one way s to set through the DIP swtch on the PROFIBUS template, another s that user nput the address. If PROFIBUS template s appled, DIP=0, the assgned address of P0918 s 10. The DIP swtch s set to zero when released, so the converter bus address s confgured by P0918 durng debug perod. When DIP s not set to zero, swtch settng s preferred, and P0918 s responsble for dsplayng the set-pont of DIP swtch. P1000 selecton of frequency set-pont: the parameter s set to CB of 6-COM lnk, the frequency set-pont communcates wth the CB. 5. Feld Control System Gven the actual feld control stuaton, we apply PROFIBUS as the bus control format and establsh the connecton and montorng between feld devces and workshops through dstrbuted dgtal controllng, so as to accomplsh automaton between heavy plate feeder control system and feld devces. Functons lke automatcally controllng the ball mll feedng, and real tme montorng of the process flow, reportng, statstcs, remote browsng are nvolved n the desgned system [8]. The CP5611 communcaton board s nstalled on both two control machnes, the CP342-5 communcaton processor model s used on PLC, and nformaton nteracton s done wth PROFIBUS. The control machne dsplays runnng state of the montorng devces n real tme, and montors real-tme data such as feedng quantty, operatng speed, load curves and bearng temperature. In addton, common functons lke nqury of hstorcal data, settng parameters, generatng statstcal analyss reports are also nvolved. PLC program handles the whole control process, correspondng commands are transmtted to ndvdual stes through DP networks, to realze automatc control. In order to realze tmely regulaton aganst basc-level producton and get a real-tme understandng of the producton status and devce runnng state, one extra server can be used to network wth the schedulng supervsor through the swtch devce, to meet the demands of 22

5 automatc montorng and managng. The network topology s shown n Fg 6 [9]. 6. Programmng desgn 6.1 PLC control program Fg 6 Network topology The man control program of PLC s made by block calls, man program of PLC s shown n Fg 7 and the control program block s shown n Fg 8. Fg 7. Man program Fg 8. Control program block 6.2 Communcaton Program Desgn between converter and PLC PP0 s responsble for connecton between the converter and PLC master staton, on one hand, master staton uses PP0 to transmts the control word (STW), frequency set value to converter 440, on the other hand, converter 440 reples status word (ZSW) nd the actual frequency output (HIW) to PLC master staton through PP0 [10]. The text structure of PP0 s shown n Fg 9. 23

6 Fg 9. PP0 text structure PZD1-PZD4: process data area, used for converter control and detecton, takng 8 bytes. STW: control word, takng 1 or 2 bytes, used for controllng start-stop, alarm reset of the converter. HSW: frequency set value, takng 3 or 4 bytes, used for modfyng the frequency set value, converter 440 feed HSW back to the PLC master staton. ZSW: status word, takng 1 or 2 bytes, defned by parameter r0052, used for dsplayng the converter status (runnng, breakdown). HIW: actual frequency output, takng 3 or 4 bytes, dsplayng converter feedback frequency. 6.3 Program Desgn of Converter Start, Stop and Runnng Left-clck the Start button n WINCC, and then M100.0 bulds connecton wth W#16#47F converter, the start-up control word s then transmtted va PQW536 to the converter s PZD control area, converter starts. Drag the slder to nput certan speed value nto MW101, n order to set the speed of the converter va PQM538, meanwhle, the converter transmts the actual speed to MW110 va PIW586. M100.2 col s energzed, and ts auxlary pont M100.2 self complements, rght-clck the start button, M100.0 wll be dsconnected [11], the start-up program desgn s shown n Fg 10. Fg 10. Program desgn of converter start-up Left-clck the Stop button n WINCC, and then M100.1 s connected, f stop control word W#16#47E s transmtted to PZD control area va PQW536, the converter s stopped. Whereafter, rght-clck the Stop button and M100.1 wll be dsconnected. The correspondng program desgn s shown n Fg 11. Fg 11. Program desgn of stoppng converter 24

7 The actual speed value of converter s converted from nteger data type to long nteger type n MW110 and transmtted to MD120, where the long nteger data s further converted to float type and transmtted to MD130. The float type data n MD130 s then dvded by e+004 and transmtted to MD140,where t s multpled by e+001 and then transmtted to MD150. Data output from MD150 s dsplayed on the nput/output doman of WINCC s operatng and montorng screen. The compled PLC programs are then saved and downloaded nto S7-400PLC [12]. The converter s operaton program s shown n Fg 12. Fg 12. Operaton program desgn Fg 13.WINCC control nterface 25

8 7. UI desgn of WINCC Montorng Confgure the external varable and processng screen, and the whole screen of ba_mddle crush_2.pdl s bult and saved. When runnng, clck the heavy plate feeder fgure on the man screen of secondary crushng system montorng, and a extra small control screen of the heavy plate feeder wll pop up, where we can manpulate the start or stop button to control the converter to start or stop, drag the slder to change the converter speed, and dsplay the converter n the nput/output doman. The WINCC control nterface s shown n Fg Confgure the upper computer The real-tme montorng nterface can be developed n a Wndows envronment, and WINCC s adopted to develop the upper computer s control UI. The control UI s manly composed of the followng parts:(1) Man nterface regon, vsually and dynamcally demonstratng the parameter varaton of feld devces, smulatng the real-tme process of ore feedng. The control data comes from the feld data and the correspondng varable defned n the kngvew software data base. Graphc object s appled to buld anmaton connecton between the feld data and the varable. (2)Sgnal nterface analyss regon: dsplayng specfed sgnal data and relatve tendacy charts, so that operators can analyze the runnng states, judge the causes and locaton of operaton falure, and make correspondng predcton. (3) Alarm message regon: when events that meets the preset alarm condton happens, the correspondng alarm pop-up wndow and sound alert s trggered untl the operator has confrmed to clear the alram. The alarm wndow s equpped wth hstorcal alarm recordng system, the events correspondng process logs are recorded for query and prnt purpose. (4)Report generaton regon: n order to handle all producton equpment and have a pooled analyses of the producton data, the embedded report generatng system of WINCC s adopted to generate all knds of analyss reports and the system functon s called to pnt these reports. 9. Conclusons The mproved automatc control system of heavy plate feeder has a hgher automaton degree and t s easer to operate. The ste operators only need to vew the secondary system processng screen and the man screen dsplay to grasp the ore quantty of each stage and the runnng status of devces. Real tme montorng makes t possble to remote control the speed of heavy plate feeder, whch further changes the feedng quantty, so that the whole crushng system s able to operate n a stable and effcent way. The result of feld operaton demonstrates that the control system s stable and relable, nearly no breakdown happens durng the tral run,. Besdes, the system gets very precse ore feedng and the operators labor ntensty decreases greatly. There s no need to adjust the ore feedng manually, routne nspecton once an hour s suffcent. Also, wth our automatc control system, the ore throughput has reached 700t/h, and the economc beneft has got on a new stage. The overload and under-load problems of mechanc devces (such as crushers) are solved too, mechanc mantenance caused by overload and energy consumpton caused by under-load are nearly zero. In addton, thanks to real-tme montorng, the dle runnng tme s reduced to 4-5 mnutes, producton cost s has decreased dramatcally. References [1] WU Xng-chun, ZHAO Jng-yan. Applcaton of ntellgent PID algorthm n fnance temperature control system [J]. Journal of Mechanc & Electrcal Engneerng, 2011, (28) 8: [2] ZHANG Yong-png. Applcaton of ntegral separatng PID control n the system of batchng system [J]. Chna 26

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