I. Introduction
With the development of science and technology and the progress of society, the water plants in major cities in China are gradually developing in the direction of “safe water supply, scientific management, and quality serviceâ€. Therefore, how to improve the quality of water supply, achieve energy conservation and consumption reduction, and achieve efficient management are the most important issues facing the current water plant. In addition, improving the level of automation and information is also increasingly important for water plants.
With the rapid development of automatic control technology, water plants have established SCADA systems to realize the entire process monitoring of water plants from water intake to water production and water distribution. However, in practical applications, there are not many truly satisfactory results. The purpose of this program is to plan from design, implementation to post-maintenance, and provide users with a solution that is advanced, easy to develop and maintain, and easy to expand and implement step by step.
Second, system requirements
1. Centralized monitoring and decentralized control
Water plant monitoring systems are usually divided into two layers: control layer and management layer. The control layer completes the measurement and control of specific water intake, coagulation, sedimentation, filtration, and water supply; the management team is mainly responsible for status monitoring, data collection, and fault alarm processing. The position of each process in the control layer is scattered. The control center in the central control room will conduct unified monitoring. Therefore, the water plant has the characteristics of centralized monitoring and decentralized control.
Based on this feature, waterworks often have little or no staff in the control link, and only experienced staff in the central control room. The goal is to achieve “no one or few people on duty.†This requires high performance of the SCADA system. If the collection, analysis, and control are not fast enough or the data transmission is not safe enough, the role of the control center will be greatly reduced. This will cause errors in the implementation of the process, and will seriously affect the water supply and Water quality. Therefore, efficient performance is the key to centralized monitoring.
2. High integration
The water plant usually implements unified status monitoring, data collection, and fault alarms in the control center. To facilitate the control center to understand all valuable data, it will require all information and data to be integrated into the control center, such as measuring data and alarms. Status, historical data, video information, etc. The control center needs to implement observation and linkage of all information through a complete set of platform system. This is a big test for the integration of SCADA systems.
3. Management and scheduling
In addition to completing normal water production and water distribution, the water plant, as a company, also has the requirements of cost management and resource allocation. This requires the computer monitoring system to have control functions in addition to the various processes, but also need to consider how to control the most cost-saving and minimize the waste of resources. In order to achieve these upper management and scheduling functions, the SCADA system needs to be capable of aggregating a large amount of process data. This data is combined with optimization algorithms to achieve professional analysis, and ultimately make a guiding decision.
Third, the system to resolve points
- Communicate with PLCs and meters in the process to quickly collect real-time data.
- Ensure data integrity, diagnose the acquisition link and communication network, and realize real-time data-based
- Redundant function of historical data and alarm data. When abnormality occurs, fast switching is performed. Data is buffered when the network is interrupted and the network speed is too slow.
- Intuitive display of actual measured data and status (such as animations, reports, trends, etc.)
- Kinds of alarms and early-warning detection, and use a variety of ways to achieve alarm notification. Intuitive accident recalls of the failures that have occurred.
- High-performance compressed storage of large amounts of high-density process data.
- Based on a large amount of stored historical data, professional optimization calculation and analysis are realized.
- Provide a variety of open interfaces for other third-party systems to call data for correlation analysis.
- Real-time, historical, and alarm data are published in an integrated manner over the Internet or a LAN, enabling users to browse in IE.
Fourth, the solution
1. System configuration
Figure 1 System Configuration Diagram
2. Software deployment
Figure 2 Software Deployment Structure
- I/O data acquisition software (I/O Server 3.0): Quickly collect real-time data from field devices, interact with SCADA software, upper level control centers, and store data in databases.
- SCADA software (KingSCADA 3.0): It shows the process flow of the pumping station and the operation status of the equipment by means of graphics, animations, reports, trends, etc., and completes the control of the operator on the host computer.
- Industrial Historian Database (KingHistorian 3.0): It stores a large amount of process data and has powerful performance in acquisition, storage and retrieval. It is the data foundation for deep analysis and statistics.
- KingSCADA Client: Based on the C/S architecture, it is the client software of KingSCADA3.0. Providing operators with the operating platform needed for daily operations also meets distributed requirements.
- KingGraphic: It is an analysis and display platform for a large amount of historical data, calculation data, and alarm data. Managers can understand the past conditions of water plants and analyze future trends through trends, reports, and historical playback.
- Computing Platform (King Calculation): Based on the running characteristics of the water plant, a variety of professional algorithms are used to perform complex calculations based on a large amount of process data.
- Alarm and event detection platform (KingA&E): Converts data to state, uses a variety of detection methods to achieve complex alarm event detection, timely warning before the accident to ensure the system is safe and stable.
- PortalProtal: It integrates various data and then publishes it in the form of a portal to a wide area network or a local area network. Users can browse from web pages.
3. Program features
- Support capabilities of hardware devices
The computer monitoring system of the water plant will communicate with various hardware devices (such as PLCs, water quality testing instruments, pump units, and unit electrical cabinets), collect real-time data from the site, and report them to the SCADA software and save it to the industrial history database. This requires the system to have the ability to communicate with various vendors' hardware devices and support various communication protocols. The I/O Server 3.0 in the solution supports more than 1,500 hardware communications with more than 3,000 hardware and supports a variety of standard communication protocols such as MODBUS, Profibus, CAN, and OPC. Make software products can be easily combined with various hardware devices.
Figure 3 Supported Hardware Devices
- Effective safety measures
Based on the characteristics of "centralized monitoring and decentralized control," the safety and stability of the "acquisition, analysis, and control" of the SCADA system is undoubtedly the most concern to users. This requires the SCADA system to have strong performance in terms of safety and stability.
KingSCADA3.0 system supports dual-system redundancy, dual network redundancy, and dual-device redundancy. It can implement switchover for server, network, and device failures, and supports independent redundant channels to ensure 1-second switching. Continuous and complete real-time data, historical data, and alarm data. The system provides a dedicated performance monitoring tool to facilitate users to understand the various information related to acquisition and transmission. When the network is interrupted, the data can be cached locally, and when the network recovers, it can resume the breakpoint. In this way, even if a network interruption occurs, the data will not be lost.
Figure 4 Independent redundant probe channels
Figure 5 Performance Monitoring Tool
- Integrated platform system
With the rapid development of automation technology, SCADA systems are no longer simply communicating with devices, displaying data, and issuing control instructions. With the continuous improvement of the management function requirements of waterworks, the water plant urgently needs an integrated platform that integrates acquisition, monitoring, control, and dispatch. This requires the combination of automation and informationization. In addition to the monitoring configuration software in the system, a decision system with analysis and scheduling functions is also required.
KingCalculation in the solution is a software platform for computing and analyzing a large number of process data combined with complex algorithms of the tap water industry; KingA&E is a software platform that translates “data†into “state†to perform early warning judgments and triggers. analysis. Their data base is the industrial history database King Historian. The final analysis information, warning information, and decision-type prompt information are all displayed on the KingGraphic display platform.
Figure 6 Platform system
- Rich system interface
In order to meet the needs of the city's unified water supply and dispatch, the water plants in various districts and counties often need to upload the data to the water company, and the water supply dispatching system of the water company will implement centralized supervision and coordination. In order to facilitate the water supply dispatching system of the water company to obtain data, the SCADA system of the water plant needs to have a rich open interface. This system consists of data acquisition software, SCADA software, industrial database software, and upper-level analysis and display software and other various types of software. With a variety of data interfaces, such as API for VC++/VB/.NET, OLEDB, ODBC, COM, etc., support SQL statement query. Using these interfaces, you can easily interact with other third-party software systems.
Figure 7 Rich interface
- Web function
Web function adopts B/S structure, can release to LAN and wide area network, the customer can realize remote monitoring through Internet/Intranet anytime and anywhere. For example, the computer in the factory director's office can browse the screen in real time through IE browser and monitor various industrial data. If you publish to a wide area network, monitoring can be performed in different places regardless of where the user is located. The advantage of doing so is that it is convenient for business leaders to know valuable data in a timely manner, even on business trips.
Figure 8 WEB browser interface
V. Case Introduction
- Guilin Dongjiang Water Plant SCADA System