Abstract: This article introduces the actual works of the Shenyang Development Zone water purification plants, from the cost savings, rational use of the second phase of the existing industrial Ethernet, and monitoring software, based on the configuration of the water plant automation control system. The composition and design of the system are described, and the hardware, communication networks, software design, and other aspects of the system are analyzed and designed. Key words: Automatic Control; PLC ; Ethernet ; monitoring configuration; upgrading 1 Introduction The Shenyang Development Zone water plant is located in the Shenyang Development Zone industrial cluster area. Phase I was completed and put into operation in May 2001, consisting of a main plant area and a deep well area. The main plant area covers nearly 20,000 square meters, with a designed capacity of 60,000 cubic meters per day. It primarily relies on manual control and lacks an automated control system. Phase II, located within the main plant area, was completed and put into operation in December 2007. With the rapid development of automation control technology and the increasing maturity of network technology, a new generation of water plant control systems will inevitably replace the previous simpler control methods to facilitate large-scale centralized control. The following are the design requirements and design scheme for the Phase I PLC automated control system of the Shenyang Development Zone water plant. 2. Process Flow and Design Requirements 2.1 Control Requirements Based on the process flow and the geographical distribution of structures, the automated control system mainly manages the chlorination room, water purification workshop, and water pumping station, and automatically controls the process flow. The system adopts a "centralized monitoring, distributed control" approach, consisting of a plant-level central monitoring workstation, distributed field control stations, and production site equipment, forming the entire plant's industrial control system. The main process parameters to be automatically detected include: influent turbidity, pH value, conductivity, influent flow rate, pressure, backwash pump valve opening position and operating status, filter effluent turbidity, filter single-tank head loss (differential pressure), clear water tank level, etc., and total water plant effluent flow rate, pressure, turbidity, pH value, residual chlorine, etc. The electrical parameters to be detected include: voltage, current, active/active energy consumption, reactive/reactive energy consumption, etc., of the power distribution system. 2.2 Communication Network Requirements: The communication system is divided into management and control levels. The management level uses 100M industrial Ethernet with fiber optic communication. The control level uses an industrial network, communicating via dedicated shielded cables. 2.3 Hardware Requirements: The system uses a PLC+PC control method. The PLC performs specific control and monitoring, while the PC uses configuration software to implement monitoring, alarm, statistics, and report printing functions. 2.4 Software Requirements: The entire plant's production management layer and production process monitoring layer should use configuration software to develop software interfaces that are easy to manage and monitor. The production site equipment layer should use PLC ladder diagram programming to design process control software that conforms to the production process. 3 Design Task Analysis From the perspective of the actual production situation of the water plant and its role in the automatic control system, the water plant's automatic control system consists of three levels: the production site equipment layer, the production process monitoring layer, and the entire plant's production management layer. [align=center] Figure 1 Composition of the Water Plant Automatic Control System[/align] The production site equipment layer includes micro PLCs and related motors and instruments in the chlorination room, water purification workshop, and water pumping station. The production process monitoring layer consists of a PLC control system and its control network. It mainly realizes the functions of controlling, monitoring the status, acquiring data, and handling fault alarms for the controlled objects in the production site equipment layer. It is the core part of the automatic control system and includes the PLC1 substation in the water purification workshop and the PLC2 substation in the water pumping station. The entire plant's production management team includes the central control room and the plant manager's office, primarily responsible for monitoring and controlling the status of the entire plant's production process, as well as fault alarms, production data analysis, and report generation. Remote control can be implemented when necessary. 4 System Design 4.1 Design Principles The design adheres to the principles of advanced technology, practicality, reliability, economy, and openness, meeting the requirements of water supply project production management and water treatment processes for automated control. It aims to achieve "centralized monitoring and management, decentralized control, and data sharing" to ensure coordinated and consistent operation of the entire water plant. 4.2 System Configuration Diagram [align=center] Figure 2 Water Plant Automation System Configuration[/align] 4.3 Hardware Configuration The host computer is an Advantech P4 industrial computer, the printer is an HP1320 black and white laser printer, the projector is a Hitachi 3180 model, the PLC master station is a GE Fanuc 90-30 series, the slave station is a GE Vermax E05, and the touchscreen is a Taiwan WEINVIEW MT510TV. 5. Detailed Design 5.1 The central monitoring system consists of three host computers (#4, #5, and #6), one printer, and one projector, with an operation display terminal. Since the second phase project already has one printer, two industrial control computers, and one projector, only one industrial control computer is needed. This control room serves as the central control room for the entire system, responsible for the centralized control, monitoring, and management of all operating conditions throughout the plant. It exchanges information with field control stations via Ethernet and has multiple screen functions, facilitating centralized monitoring and management. The #4 host computer primarily monitors the process flow of the second phase's water purification workshop, clear water tank, water pumping station, and related supporting equipment, as well as various process and electrical parameters of the incoming and outgoing water. It is also responsible for printing various reports and outputting data. A communication interface is reserved with the company's dispatch management system, enabling real-time detection and monitoring of the status and process parameters of various equipment in the pipeline system within the water plant's supply range. It communicates with each field station through the plant's real-time communication network, providing operators and managers with a user-friendly human-machine interface for operation management, and allowing for real-time and scheduled recording and report printing. The #6 supervisory control computer primarily monitors the process flow of the water purification workshop, clear water tank, water pumping station, and related supporting equipment in Phase I, as well as various process and electrical parameters of the incoming and outgoing water. It is also responsible for printing various reports and outputting data. The #5 supervisory control computer serves as a hot standby. When the master station fails to communicate, the standby station immediately takes over all functions. When the master station recovers, it first retrieves the historical trend data and alarm records stored during the failure period from the standby station. Then, it automatically switches all control functions back to the master station, which continues to control the entire system. The standby station returns to hot standby mode and continuously updates all data synchronously with the master station as the data source. The central monitoring computer is selected for its fast operation and stable performance. The monitoring software is a software package that is flexible in configuration, powerful in function, and user-friendly in interface, and has been successfully applied in the water supply and drainage industry. The main functions of the central monitoring system are: remotely monitoring each PLC field substation, receiving various data collected by the PLC in real time, establishing a database of detection parameters for the entire plant; processing and displaying various data; and monitoring the dynamic simulation graphics of the entire plant's process flow and various details. From the detection items, display historical records and trend analysis curves as needed. Display the operating conditions and accident alarms of key equipment parameters, and print tabulations. Compile and print daily, monthly, and annual production statistical reports. Display the process flow and the working status and alarms of various equipment in real time on the projection screen. Store various data in real time. 5.2 The on-site monitoring system consists of the water purification workshop monitoring station and the water pump room monitoring station. Water purification workshop monitoring station: responsible for managing PLC1 substation. Located in the water purification workshop control room, it mainly consists of two host computers (#1 and #2) and a printer, equipped with an operation display terminal. Host computer #1 mainly realizes the automatic control of electrical control equipment and process flow in the water purification workshop, as well as the automatic detection and monitoring of key parameters, and is responsible for printing various reports and outputting data. Host computer #2 is mainly responsible for the automatic detection and monitoring of various electrical control equipment and key process parameters in the water purification workshop. The two host computers are hot standby for each other. Water pump room monitoring station: responsible for managing PLC2 substation. Located in the control room of the water pumping station, it consists of a No. 3 host computer and a printer, equipped with an operation display terminal. It automatically detects and monitors key process, water quality, and electrical parameters and statuses, controls and monitors the operation of water pumps and valves, and participates in the variable frequency speed control of the water pumps based on the outlet water pressure. 5.3 The field equipment control unit is the control equipment closest to the controlled site. A micro PLC is used as the field equipment control unit in the design, exchanging data with the field control station through an industrial fieldbus interface. The micro PLC consists of a power module, communication module, digital input/output module, and analog input/output module, controlling the opening and closing of valves via a bus, and collecting the operating status and parameters of valves, water pumps, and instruments. ⑴ The micro PLC control system for the filter tanks in the water purification workshop is responsible for detecting the liquid level and head loss of the filter tanks and controlling the electric valves of each filter tank. A common PLC1 is also set up to manage and control the backwashing pumps and valves required for the operation of each filter tank, and to issue backwashing commands to the filter tanks. Each filter compartment has an independent micro PLC to monitor its operating conditions. Each micro PLC is equipped with a touch screen as the display and operation interface, showing the filter's operating status and allowing for local operation when necessary. ⑵ PLC1 is responsible for collecting the operating status and outlet pressure of equipment such as the backwash pump and making corresponding adjustments to achieve monitoring and automatic control of the filtration and backwashing process. Operators can also manually control the process. ① Control functions implemented: Main functions: Backwashing cycle for each filter compartment, water level monitoring for each filter compartment, head loss monitoring, and backwash pump outlet pressure. Main monitoring equipment: Filter inlet valve, outlet valve, drain valve, backwash inlet valve, backwash pump, and 12 filter compartments. ② Monitoring of main operating conditions: Operating conditions of each filter compartment: Start-up, shutdown, request for flushing, flushing, and fault. Operating conditions of the four valves in each filter compartment: Fully open, fully closed, outlet valve position, and fault. Main parameter display: Water level and head loss for each filter compartment. ③ Control Content: Filter Cell Operation Control: During filtration, the PLC adjusts the opening of the filter outlet valve based on the filter level to ensure a constant level within the filter. Backwash Control: While controlling the filter process, the PLC also determines whether backwashing is needed. There are three conditions for backwashing: ① Filtration Cycle: The operator sets the maximum filtration time on the PLC according to the process requirements. When filtration begins, the PLC starts timing and compares the actual filtration time with the set value. If the two values ​​are equal, the filter PLC sends a backwash request to the common PLC. ② Head Loss Value: The maximum head loss value for the filter is set on the PLC. During filtration, the head loss sensor continuously measures the head loss value of that filter cell. The PLC compares this value with the set value. If the value is greater than the set value, the filter PLC sends a backwash request to the common PLC. ③ Forced Method: Operators can force the filter PLC to send a flushing request to the common PLC by operating the function keys on the filter PLC according to on-site needs. ⑶ PLC2 monitors the operation of the motors of the five water pump units and the outlet valves, monitors the stator temperature and power consumption of the pump motors, plots the characteristic curves of the pumps running in parallel according to the water volume required by the water plant, and monitors the substation system of the water pumping station and the water quality, flow rate, pressure, clear water tank and suction well levels of the treated water. This station is responsible for monitoring the substation system of the water pumping station and the equipment in the water pumping station. ⑷ The micro PLC in the chlorination room is responsible for the automatic control of the chlorination equipment and the operation of the chlorine leakage neutralization device and the fan, and makes corresponding adjustments. It automatically controls the chlorination amount according to the residual chlorine content and flow rate of the treated water, realizing the monitoring and automatic control of the chlorination and chlorine leakage alarm process. Operators can also manually operate and control it. Main monitoring equipment: chlorinator, chlorine leakage neutralization device, axial flow fan. Control Content: Collect data from the residual chlorine analyzer, control the chlorine dosage, and activate the chlorine neutralization device based on the status of the chlorine leak alarm, as well as periodically operate the axial flow fan, etc. 5.4 Communication Network For an automation project, especially a medium-to-large-scale control system, network selection is crucial. First, the network must be open to facilitate the integration of different devices and future system expansion; second, the network type should be selected based on the transmission performance requirements of different network layers; third, considering system cost, equipment compatibility, and suitability for the site environment, the network standard used at different layers should be determined. Based on the existing industrial Ethernet system in the first phase of the plant's upgrade project, the following connections were adopted: A 100M industrial Ethernet connection was used between the water purification workshop, water pump room, and central control room, with fiber optic cable as the transmission medium. A standard industrial network was used between PLC1 and the filter tank and chlorination room, and between PLC2 and the controlled equipment, with shielded copper core cable as the transmission medium. 5.5 Software Design Powerful configuration software is used to manage and maintain the entire water plant's automated control system. The host computer software implements the following functions: Dynamic Flowchart Display: Dynamically displays the entire plant's process flow diagram and the flow diagrams of each process unit, and allows selection of multi-level detailed diagrams on the flow diagram. Dynamic Data Display: Displays a list of values ​​and ranges for various analog signals, switch signals, and various cumulative signals, vividly presented in real time using sliders, buttons, switches, indicator lights, colors, percentages, and fill functions. Trend Curves: Displays the change curves of major process parameters, historical curves and real-time curves of various analog quantities, and allows comparison of multiple parameters on a single graph. Report Printing: Real-time reports, daily reports, monthly reports, and annual reports. Control and Adjustment Functions: Allows adjustment of various controlled process parameter setpoints on the dynamic flow diagram and detailed diagrams, and enables manual/automatic switching and control of the operating conditions of each piece of equipment. Alarm Function: When a fault occurs, the central control room and corresponding PLCs will issue an audible alarm. The control software will automatically pop up a detailed diagram of the corresponding fault point, display the fault phenomenon, and provide reference solutions. The central control room will provide voice prompts and print alarm and fault log files. Safety Function: Encryption is implemented according to different operation levels. Operator employee numbers and all operation information are recorded. Database Management Function: Production database, operation information database, and fault information database can be established. Data Processing Function: Real-time and historical data can be used to calculate key production indicators. Water and electricity consumption and unit water and electricity consumption cost analysis and calculation can be performed. Online Modification: The program can be modified online. To facilitate engineer debugging, the same configuration software Cimplicity 6.0 is used in Phase II. 6 Performance Analysis 6.1 System Reliability, Stability, and Lifespan The design of the system components meets true industrial standards and complies with domestic and international safety standards. It is easy to configure, easy to wire, easy to maintain, has good isolation, a robust structure, is corrosion-resistant, and can adapt to a wide temperature range. The system has good electromagnetic compatibility, can withstand the strict requirements of industrial environments, and has an average lifespan of more than 15 years. 6.2 System Advanced and Economical Features This control system has a complete self-diagnostic function, which can automatically diagnose any component fault during system operation and reflect the fault status, fault time, fault location, and related information in a timely and accurate manner in the monitoring software. After a system fault occurs, the I/O status can return to the state preset by the system according to process requirements. After the system is running, it can conveniently, quickly, and accurately control the operation of each stage of production, greatly saving human resources and improving production efficiency. 6.3 Expandability and Compatibility This system adopts currently advanced mainstream products and has strong compatibility. To ensure that control requirements are met during future expansion and renovation, the system's expandability was fully considered during the design, retaining 20% ​​system redundancy while meeting existing functional requirements. 7 Conclusion With the completion of this automation system, the water plant's production automation will form a production self-control information network mainly based on information collection, integration, and transmission of the production process, closely integrated with the enterprise's production process scheduling, water quality monitoring, automatic chemical dosing, and other technologies. This prompts water plants to widely utilize computer and network technologies in production, marketing and office work, optimize the enterprise in all aspects, and form a standardized and modern information management system. This reduces production costs and expenses, and improves the economic benefits and industry competitiveness of the enterprise. References: [1] GE 90-30 plc user manual. [2] Introduction to GE Cimplicity software. [3] Lu Linji, Wang Jian, Jiang Longkang. Programmable Controller Principles and Applications [M], Beijing: Tsinghua University Press, 2002. [4] Wang Weixing, ed. Programmable Controller Principles and Applications [M], Beijing: China Water Resources and Hydropower Press, 2002. About the author: Zhang Fengzhong , male, born in 1974, School of Information and Control Engineering, Shenyang Jianzhu University, Master, Lecturer, major research on intelligent control systems.