Power Plant Coal Conveyer Coal Link PLC Control System Zhang Jijie1 Che Yanbo1 Zhao Lihua2

1School of Electrical Engineering & Automation, Tianjin University, Tianjin China E-mail: ybche@tju.edu.cn

2Tianjin Entry-Exit Inspection and Quarantine Burean of P.R.China E-mail: zhaolh0@tjciq.gov.cn

Abstract-Power plants conveying system includes coal link and blending links. This design only involves conveying coal link in the system. This power plant coal conveying link PLC control system is aimed at making some improvement for the traditional coal-fired power plants which is a relay-based semi-automatic conveying control system with the features of more faults, the lower reliable of the operation. This paper adopts the advanced PLC as control system including the hardware configuration and software design for the conveying system. Adopting kingview as the PC monitor realizes the real-time monitoring of the conveying system.

Keywords-Conveying system; Programmable logic controller; PC monitor

I. INTRODUCTION

Along with the rapid development of the electric power industry and the requirements electricity demand of people unceasing increase, large capacity and large units of coal-fired power plants conveying system has gradually hold the dominant position in Chinese power plants.Therefore, valuing the safety and reliability of the coal-fired power plants conveying system work, has deepened into the conveying system to realize comprehensive harness [1]. It is the guarantee to realize safety, civilized, economic and scientific management for coal-fired power plants.

The composition of the conveying system is consisted of coal link and blending link, and this design only involves coal link. In this article the main aspects is related to the coal link about PLC control and the host computer monitoring system.

Fig.1: Conveying system process flow diagram

The running style of this system includes four operating modes parallel first-line, parallel second-line, crossover modes first - second-line, crossover modes second-line - first. This paper takes parallel first as example to explain the process of coal conveying system. The coal feeder gives the coal in coal # 1 or # 2 belt conveyor, arrived the shaker through the 1 # belt conveyor. After the choice of shaker the coal fell on channel 1 or channel 2 through

tee baffle. There are shaker, broken plow, the dust catcher and except iron respectively on the 2 channels. Through the select of the shaker, the broken coal were shipped to # 3 belt conveyor, the lump coal is broken by the plow through another channel, then the smashed coal is sent to 3# belt conveyor, then to 5 # belt conveyor. In the # 5 belt continue the follow-up work for coal blending [2].

Conveying system normally operates by adopting parallel first or second operation, a parallel normally operated and the other used as the standby to ensure conveying system operated reliability. And crossover modes are used when the equipments malfunction, parallel first or parallel second-line cannot normally operated to fully guarantee the reliability of conveying system.

This system includes the microcomputer monitoring and PLC control section. The control function about equipments is mainly achieved by PLC [3], PC industrial control computer completes equipment The running condition monitoring of the equipments, belt running deviation monitoring and accident record function are achieved by PC.

II. UPPER COMPUTER DESIGN SCHEME

The upper machine adopts advanced industrial controlling computer. It can realize the emersion of production site of each device operation state through the configurationinterface. Control signal is sent to PLC through clicking the button on the interface. At the same time lower level computer feedback signal is displayed in CRT, and inventory and print the working conditions of each device.

Kingview is a human-machine interface software in Chinese. Adopting multithreading, COM components and other new technologies, realizes real-time diversity working way. The software is strong function with the characteristic of performance outstanding, stable operation and reliable in quality [4].

The microcomputer monitoring picture includes the total control interface of conveying system, Manual operation panel, accident alarm interface. The total control interface of conveying system is showed as Fig 2. The whole process of conveying system can be monitored through this picture and have a corresponding monitoring for the operating conditions and the fault of the system. When an operation mode is chosen, control interface indicates the operation condition of the corresponding operation mode. Through this interface can switch to others interface

"manual operation panel", "accident alarm interface", "exit system".

The interface of manual operation panel is showed as Fig.3. This interface monitors the operation of the control

system when manual operation is used. Through this interface can start any one of device without chain when the fault equipment needs to be tested.

Fig. 2: Conveying system total control interface

Fig. 3: Manual control panel interface

Fig. 4: Accident alarm interface

Accident alarm interface is used to monitor the conveying system when it is in fault and it is showed as Fig.4. This control interface indicates the fault conditions of the system device with corresponding indicator. It can record fault information in fault record form and it is fault record is facilitate to be inquired.

Three surfaces can be switched between each other and the running time of the current system displayed in the running state. It can monitor conveying system for

real-time. Upper computer monitor the operation state and the malfunction of devices.

III. PLC DESIGN SCHEME

The design of PLC includes three parts the hardware design, software design, the program design. PLC design mainly realizes the specific technological requirements of the conveying system.

1. PLC hardware configuration PLC hardware configuration is showed in table 2.1 It includes power template PS307, CPU template CPU314-2DP, extended interface template IM360, three

digital input templates SM331, a digital output template SM322, two analogue input templates SM331 and peer-to-peer communication template CP340 [5].

Table 1: PLC hardware configuration

Slots S.N. 1 2 3 4 5 6

template PS3075A

CPU314 IM360 SM331

32x24V DC SM331

32x24V DC SM331

32x24VDCAddress

range / / / I0.0-I1.7I2.0-I3.7

I4.0-I5.7I6.0-I7.7

I8.0-I8.7I9.0-I11.7

Table 1: PLC hardware configuration (continue)

Slots S.N. 7 8 9 10

template SM32264x24V DC

SM3318x12V DC

SM3318x12V DC CP340

Addressrange Q0.0-Q7.7 PIW272-PIW287 PIW288-PIW303 /

It is an economical solution for serial communication through the point-to-point connections. The communication processor of CP 340 is a completely economical solution to satisfy serial communication.

It can be used in SIMATIC S7-300 and ET 200M. Data transmission with various nodes can be realized through performing a variety of standard agreement.

2 PLC software design

The control mode of this design includes automatic control and manual control. The start running of equipment needs interlock between each device which the start of a device is controlled by others in the mode of automatic control to ensure the safety running of the system. The startup of devices is inversed from the coal flow and the stop is with the coal flow. When the equipment is in fault in the process of starting, this mode can guarantee the equipment which is before the fault point inversed coal flow various stops immediately. The launch of subsequent equipment of broken plow malfunction start-up when broken plow has started, the broken plow must stop delay some time to ensure the broken plow without load in the next start. The purpose of the delay stop of various equipments along with the coal flow direction is the same with the broken plow. The start of parallel first is showed as Fig 5.

Fig. 5: Parallel first start flowchart

The mode of automatic control will be served as the main operation state of the power plant conveying control system. The main task of this mode is to realize the management for each device of the conveying system. The management includes the start and stop of equipments and the automatic treatment for fault equipments. It is simple and reliable for power plant conveying control system to realize the control function

in the mode of automatic control and the automatic control is used as the stock state of the system operation.

Table 2: Parts address assignment

Address Annotation

I 0.4 Parallel second-line start

I 0.5 Crossover modes first - second-line startup

I 2.3 2# Tee connect parallel second-line

I 3.2 3# Belt-conveyors contactor

I 4.7 4# Belt conveyor tear

Q0.0 1# Belt-conveyors start

Q0.3 4# Belt-conveyors start

Q0.5 6# Belt-conveyors start

Q0.6 1# Broken plow start

Q1.0 1# Vibrating screen start

Q1.2 1#Coal feeder start Q3.0 4# Belt conveyor malfunction indication

M1.6 4# Belt conveyor malfunction indication

M6.2 6# Belt conveyor middle quantity

M6.3 4# Belt conveyor middle quantity

Table 3: Analog address assignment PIW272 1# Vibrating screen fault of bearing temperature

PIW274 2# Vibrating screen fault of bearing temperature

PIW276 1# Broken plow fault of bearing temperature PIW278 2# Broken plow fault of bearing temperature

PIW280 1#Coal feeder fault of bearing temperature

PIW282 2#Coal feeder of bearing temperature

PIW284 1# Belt conveyor pressure sensor

PIW286 2# Belt conveyor pressure sensor

PIW288 3# Belt conveyor pressure sensor

PIW290 4# Belt conveyor pressure sensor

PIW292 5# Belt conveyor pressure sensor

PIW294 6# Belt conveyor pressure sensor

IV. DEBUGGING RESULT

In order to ensure the reliable of the operation for conveying system, the correctness and feasibility of the program is assured by simulating the program in the process of program design. Here taking troubleshooting as an example introduces the simulation of PLC program. The tearing of no.4 belt-conveyor is seen as a fault point in the mode of crossover modes first - second-line to introduce the automatic treatment about the fault equipment. To consider the special control requirements of broken plow, so taking the fault of NO.4 belt-conveyors for example. When NO.4 belt-conveyor runs deviation severely I4.7 will be set to “1” in simulation software, and it is showed in Fig 6. The equipments before NO.4 belt

conveyor stop immediately and it is showed in Fig 6 - in Fig 8.

Fig. 6: Equipment at the fault point stop immediately

Fig. 7: Equipment before the fault point stop immediately

Fig. 8: The broken plow before fault point delay stop

Because the broken plow is before the fault point, it isn’t allowed to stop immediately to avoid starting with load. Therefore the plow can not stop immediately but stop after a period of time.

From the simulation result we can see that this design realizes the control requirements for the broken plow. NO.5 belt-conveyor stops after a delayed time of 1Min.It is showed in Fig10. From simulation process we can see that the design of fault handling process for this system conform to the control requirements for conveying system

V. CONCLUSION

The design is about the improvement of the existing problem for a long time in the conveying system. The traditional coal-fired power plants conveying system is a kind of semi-automatic conveying system based on relay and contactor. Equipments often appear belt running deviation, tearing belt and other failures in operation period for the environment condition of the system is poor

and affect the normal operation of the conveying system. This design fully considers the reliability requirement of the power plant conveying system and adopts the advanced programmable controller (PLC) as the lower level machine and kingview as the PC monitor. The stability is strong enough to adopt distributed structure. This design adopts corresponding treatment for the possible fault of the conveying system which is fully considered to guarantee the reliability of the system.

This article according to the requirement of the power plants conveying system respectively describes the design process the conveying control system based on PLC from the possible sides of the scheme demonstration, PLC selection, PLC program design and PC monitoring system design. Based on PLC control system for power plant coal has been widely applied in industrial field. Compared with relay control system, its control ability is more reliable, the operation is more stable and reliable and the hardware is more concise. Process online monitoring for the power plants conveying system is realized in upper machine and can carry remote monitoring with network. The fault rate of the system reduces greatly and the running is more automatic and intelligent.

ACKNOWLEDGMENT

I would like to express my warmest gratitude to Xing Baoling, for her instructive suggestions and valuable comments on the writing of this thesis. Without her invaluable help and generous encouragement, the present thesis would not have been accomplished. At the same time, I wish to thanks the schoolmates in my lab who helped me search for reference and supported me for a long time. My heart swells with gratitude to all the people who helped me.

REFERENCES

[1] YuQingGuang, DingRenJie, MinYong ,WangShiCheng. Yuanbaoshan Power plants conveying process control and monitoring protection system research power system automation1998 22(4) 40-46

[2]WangBaozhong. A comment about coveying coal system of comprehensive treatment . China electric power enterprise management , 2003 23(20) 12—17

[3]LiuZhiyuan. Programmable controller principle and the application in the power plant . China power press. 1998

[4] WangZhifeng.Industrial control configuration software[M] . BeiJing; Publishing house of electronics industry, 2007.

[5] A1lan Liska RSLogic 500 PLC User Mantml RockwellInternational Corporatioll’2002 22(15) 25—32

BIOGRAPHY

Zhang Jijie obtained his bachelor's degree of electrical engineering degrees from University of Jinan in 2010. He began studying for a master's degree in Tianjin University in 2010.His major is electrical engineering. During the undergraduate and graduate study, he received several scholarships “Outstanding Individuals of University of Jinan” and “Outstanding Members of University of Jinan”(2010).

Che Yanbo received his B.E degree from Zhejiang University in 1993, and obtained his M.E and PhD degrees both from Tianjin University in 1996 and 2002 respectively. The major fields of study were Industrial Automation and Power System respectively. Now he is an associate professor in the School of Electrical Engineering & Automation, Tianjin University and he is the tutor of graduate students majoring in Power Electronics and Drives. In recent years his research interests focus on the field of renewable energy, especially on the inverter technology for the micro-grid operation. He has taken charge of many projects in the field of electrical engineering and control, so far he has published over 50 papers..

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