PLC-based SCADA system for oil storage and application

Prévia do material em texto

PLC-based SCADA system for oil storage and 
application 
Wang xibin 
North china institute of aerospace engineering 
LangFang, China 
 
Li guohong Wei xuejie 
North china institute of aerospace engineering 
LangFang, China 
 
 
Abstract—In the paper, configuration software and PLC 
are applied to construct SCADA System of the petroleum 
transportation. A petroleum storage and transportation 
database is created, which provide a large amount of 
experimental data to the research of petroleum storage and 
transportation and provide the basis for the promotion of 
new methods and new technologies. 
Key words-SCADA system; petroleum pipeline; data 
collection; database 
I. INTRODUCTION 
SCADA system, which namely is the data acquisition 
and supervisory control system, is a production process 
control and scheduling automation system basing on 
computer, network and modern control theory. SCADA 
system can supervise the field equipment running, so that 
it has the function to collecting data, controlling 
equipment, detecting state, adjusting parameter, querying 
alarm signals, and querying historical data etc. SCADA 
system is widely used in the field of power systems, 
sewage treatment, oil and gas pipeline and petrochemical. 
In the process of petroleum storage and transportation, 
temperature, pressure and flow, controlled by varieties of 
electric valves and pumps, are the main monitoring 
parameters. The changes of temperature and pressure will 
lead to the change of the petroleum storage and 
transportation. In order to achieving the most effective 
petroleum storage and transportation under different 
environments, temperature, pressure and flow, petroleum 
storage and transportation database is established. The 
database provides the basis for petroleum storage and 
transportation to adopt different ways and methods in 
different temperature, pressure and flow. 
By constructing large-diameter, multi-function, 
high-automation petroleum test loop, the petroleum 
storage and transportation data can be obtained under 
different environments. The loop provides reliable and 
accurate test data to petroleum storage and transportation 
station, which maximize petroleum storage and 
transportation, and reduce the maintenance in storage. 
II. REQUIREMENT ANALYSIS 
At present, a number of small petroleum indoor test 
loops have been set up in the world. The experimental 
data and experience to each kind of crude oil transmission 
have been obtained, but their differences still exist in long 
pipeline applications. So test data can’t be fully applied 
into practice, it only plays a vague guiding significance. 
In addition, the actual pipeline can not perform Shutdown 
and Restart reliably, and can not effectively monitor the 
characteristics of the external environment such as the 
geothermal field. In order to get more real data of 
petroleum storage and transportation under different 
environments, and to provide reliable and accurate test 
results for the storage and transportation stations, and to 
store petroleum scientific, and to reduce maintenance in 
storage, it is necessary to build a large-diameter, 
multi-function , high-automation dual-pipe test loop. So 
breakthrough of a crude test loop from indoor to outdoor 
is achieved. 
In order to simulate the actual long-distance pipeline 
operation accurately, soil temperature field around the 
ring road, which is applied to monitor the soil 
temperature impact of petroleum storage and 
transportation, is established with 30 intelligent 
temperature detectors. Then crude oil stored in the tank 
will be transmitted to the experiment ring road through 
experiment pump, and various experiments will be 
completed. Data acquisition and equipment control are 
achieved by SCADA system. The test content for Ring 
Road include: crude oil rheology test; Shutdown and 
Restart test; crude oil wax deposition test. The test can be 
extended to vibration test and leak detection test. 
The data for the above experiment content are 
monitored and set by automatic monitoring system. 
The main functions are as follow: 
• To collect, store and handle data of all types of 
live instrumentation and process equipment. Live 
instrumentation and process equipment consist of 
differential pressure sensor (the transmitter), 
pressure sensors, temperature sensors (the 
transmitter), the circulating pump and various 
electric valve. 
• To test the operation state and breakdown of 
various implementing agencies. 
• To dynamic show technology flow chart, 
real-time curves and historical curves of 
experiment ring road. 
• To provide interactive window, instrumentation 
and equipment range, and control parameters 
setting. 
• To show all kinds of experimental parameters, 
processing and other relevant parameters. 
• To instruct breakdown and alarm by sound and 
light. 
This article comes from Discipliones focus on the development of 
 Hebei province in “Detection Technology and Automatic equipment” 
978-1-4244-8039-5/11/$26.00 ©2011 IEEE
Field tem
perature
Field pressure
Field flow
Electric control 
valve
C
irculating pum
p
B
eater
• To control temperature of the crude oil in the 
experiment tube according to regulate the 
proportion of cold oil and heat oil, to meet the 
test requirements. 
• To draw isotherm in accordance with the 
requirements of experiment to various 
temperature fields. To print experimental data, 
laboratory reports. 
• To establish a complete operations database of oil 
storage and transportation. 
III. SCADA SYSTEM ARCHITECTURE 
The entire structure to the Ring Road SCADA 
systems are used PLC of AB company as controller, and 
adopt the special network CONTROLNET for data 
exchange. The structure is shown in Fig. 1. 
In the hardware architecture of SCADA systems, the 
upper computer can share data between related 
management departments through Ethernet. 
Figure 1. SCADA system configuration 
IV. SYSTEM CHARACTERISTIC AND FUNCTION 
A. Monitor Software characteristic of upper computer 
 Friendly interface: all operation screens are 
completed by configuration software Citect, 
which operations are simple, convenient and fast. 
Operation station can be modified online. 
Unexpected events can be recorded. Alarm time 
for the valve opened and high or low level limit 
can be queried. 
 Good versatility: the system is designed with 
high-performance PLC and redundancy control. 
So it has the characteristic of flexible assembly, 
configuration convenience, good portability and 
adaptability. 
 High security: Multi-level password management 
ensures the safe operation of systems. 
B. Characteristic of down computer 
SCADA systems use PLC of AB companies as 
controller, and its main features are as follow: 
 High reliability: As a special industrial field 
processed controller,PLC have strong 
anti-interference. 
 Flexible configuration and expedient expansion: 
PLC of AB company is designed with module 
structure, can be combined to various control 
needs, is easy to expand. The features and 
adaptability of system are improved. 
 Special Control-Net network communication: 
data between modules or the upper and down 
computer are shared through a special 
Control-Net network. 
 Low trouble. 
 Cost-effective. 
C. Function 
 Heat standby Data: Heat standby Data of 
dual-CPU is realized by the heat standby module 
of AB. 
• Data collection: remote data is collected by data 
modules. 
 Real-time monitoring and management: process 
parameters, valves, and all kinds of warning 
signals in real-time monitoring are real 
timemonitored, processed, recorded and 
displayed. And the data are classified, stored in 
database of oil storage and transportation.Local and remote control. 
V. SCADA SYSTEM PRINCIPLE 
A. Configuration frame of system control 
The control configuration frame of SCADA system is 
shown in Fig. 2. 
B. System control principle 
Two same CPU modules and two SRM heat standby 
modules are configured in the system, which realize heat 
standby data of a dual-CPU. A special ControlNet formed 
telecommunications network consist of four CNBR 
modules and a PCIC card, which exchange data between 
the operation station and down PLC, and complete the 
control order sending and the data uploading. Digital 
input and output of field electric valve are performed by 
six digital output modules and nine digital modules. The 
parameters such as temperature, pressure, flow, liquid 
level, converter and some electrical valve state are 
collected by 6 RTD modules and four analog input 
modules. Converter and opening-limiting controlled 
electric valve are controlled by an analog output module. 
There are more than 320 digital inputs and outputs, 
analog inputs and outputs in whole system. System 
software can control closed-loop PID of three field 
control valves, so that the data can be colleted better, and 
the database of the oil storage and transmission are 
established. 
 
Figure 2. System control configuration frame 
C. Design of system software 
PLC software is designed with RSLogix5000 of 
ROCKWELL companies. It mainly consists of main 
program, initialization, reset, alarm and display, data 
processing and nine experimental processes. There are 42 
sub-programs, and flow charts of sub-programs are 
omitted. Flow chart of main procedures is shown in Fig.3. 
The programs of operator station are written by 
configuration software Citect. More than 50 configuration 
screens are completed. The Excel database used to store 
all kinds of storage and transportation data is created, so 
various experiment databases in oil storage and 
transportation are created. 
VI. CONCLUSION 
After being run in field, SCADA system is fit to the 
design requirements, and can collect various parameters 
of crude oil storage and transportation, and can control 
field equipment, and create databases to petroleum 
storage and transportation running in different 
technology, and calculate the best conditions for crude oil 
transmission by relevant software, and simulate the 
operation of the real pipeline. In the end, a powerful field 
test ring road is formed.. 
 
 
 
 
 
 
 
Figure 3. Flow chart of main program 
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