The following is the relevant content about water supply and drainage automation technology brought to you by Zhongda Consulting for your reference.

Computer automation SCADA (Supervisory Control and Data Acquisition) technology, also known as computer four remote (telemetry, remote control, remote signaling, remote adjustment) technology, has been widely used in the water supply and drainage industry and has achieved good economic results. Benefits and social benefits have formed an industrial scale that benefits society. How to guide the development of this technology, cultivate the water supply and drainage automation market, and then promote the development of the automation industry is a very meaningful task. To this end, this article provides an overview of this technology to serve as a starting point.

1. Technical analysis of SCADA system

SCADA technology is based on 3CS (Computer, Communication, Control, Sensor). The above four technologies have developed rapidly recently, and new technologies and new products are constantly being introduced. At the same time, many old technologies and products are ruthlessly suffering the fate of being eliminated. How to use new concepts, new technologies, and new products to build a SCADA system suitable for water supply and drainage with powerful management functions, strong reliability, good on-site installation interface, easy operation and maintenance, and low price is what customers in the water supply and drainage industry need. The responsibilities of SCADA system integrators are described below in terms of 3CS technology:

Computer (Computer) technology

In recent years, computer PC technology has been updated at a rate of more than one generation every year. Rapid development. The powerful hardware platform (main frequency 300M or above, CPU built-in MMX technology, memory 128M or above, hard disk above 10G and high-speed CD? ROM and DVD? ROM drive, etc.) supports the constantly updated Windows operating system Windows software and network technology. The powerful PC system platform not only gets rid of the troubles of DOS operation, but also relieves the embarrassment of keyboard operation of the PC, making the PC widely used and creating conditions for building a high-function SCADA system. As we all know, in the SCADA system, the PC is mainly used as the Master or dispatch center. Recently, many manufacturers at home and abroad have launched Windows-based configuration software for SCADA. These software platforms can complete data collection related to water supply and drainage dispatching (providing communication drivers with various PLCs or other intelligent devices, dynamic data exchange DDE functions and OLE technology, etc.), data processing, data display and data recording. It has a good graphical human-machine interface and MMI has trend analysis and control functions. It provides a perfect means for optimizing the dispatch of water supply and drainage, saving energy and reducing consumption. The network function of PC provides many unexpected functions for the construction of multi-level dispatching SCADA system and participation in water plant management. The cost of continuously updating the PC software and hardware platform in the SCADA system does not account for a large proportion of the SCADA system construction cost, but it has a greater impact on improving the function and reliability of SCADA. It is cost-effective to invest in strengthening the construction of the dispatch center.

The main problem currently is that there is no domestically produced SCADA configuration software specifically for water supply and drainage automation, and the purchase price of general configuration software is relatively expensive. Organizing the production of SCADA configuration software that is standardized, affordable, and suitable for water supply and drainage

Software has broad prospects and is also an important part of building China SCADA, China's water supply and drainage automation system.

2. Communication technology

The choice of communication technology and equipment is the most colorful part of building a SCADA system. Whether the SCADA system design is reasonable, the choice of communication technology is very important. Due to the integration of various communication technologies, trying to explain them by classification is very difficult and full of loopholes. Here, for the convenience of description, they can only be classified far-fetchedly.

1. Network technology LAN WAN and INTranet

We regard network technology as part of SCADA communication. Computer network interconnection and expansion technologies based on TCP/IP, such as gateways, routers, bridges, repeaters, and remote access services; memory-based dynamic data exchange technologies; open database-based access technologies, etc. constitute control networks and information. In fact, this part should be the management part above the SCADA system, so I won’t go into details here.

2. Serial interconnection bus

RS?232, RS?485 and USB (Universal Serial BUS), the first two are well-known, and USB was recently launched High-efficiency, plug-and-play, hot-swappable interface.

1.2.3. Measurement and control bus standards such as Bitbus, Profibus, PROWAYC, PHOEBUS, HART, CAN, Dupline, L2, Modbus, SDS, ControlNET, FIP, SERCOS, FF, Lonworks, etc. The above various measurement and control bus standards are continuously penetrating into the SCA DA system, especially the communication applications between the field, instruments and intelligent terminals.

1.2.4. Wireless communication

Such as microwave, spread spectrum communication, satellite communication, iridium communication, ultra-short wave communication, short wave communication, GSM, CDMA, two-way wireless paging, etc. Some of the above wireless communications are applications of public data networks. Generally, the most commonly used wireless communications are ultra-short wave 200MHz communications. In particular, it should be pointed out that the developing two-way wireless paging will play a very important role in the communication of pressure measurement terminals in water supply and drainage SCADA, water source well groups and urban drainage network SCADA systems, and is both reliable and cheap. means of communication.

1.2.5. Cable communication

(1) Public *** data network PSDN ISDN and B?ISDN, especially B?ISDN integrated broadband data network and optical fiber to the home project The value-added services will greatly facilitate the construction of communication functions in urban water supply and drainage SCADA systems, such as pressure measuring points, water source wells, sewage monitoring stations, etc.

(2) Self-built wired network generally uses twisted pair as the medium. Each PLC manufacturer and communication manufacturer has developed closed and open wired communication system protocols respectively, and has corresponding product supplies, such as the 6DC MODEM of Israel RAD Company, the G enius BUS of GE fanuc, and the L2 of Siemens, etc., all of which are SCADA. The system provides good means of communication. It is widely used in SCADA systems in water purification plants and sewage treatment plants.

1.2.6. Carrier communication technology

Power carrier technology has been debated for many years. Recently, an article reported that Siemens has corresponding carrier communication equipment for sale. It is believed that this technology will have good prospects. . By applying it to SCADA in water purification plants and sewage treatment plants, the system can be constructed without wiring.

1.2.7. Optical fiber communication

Optical fiber communication is widely used in information communications due to its high bandwidth and high anti-interference performance. Application conditions are also available in SCADA systems. OZD485 produced by HIRSCHMANN, a German company, is used for optical to electrical 485 protocol conversion. It can be applied to: Partyline, SINEC, L1, L2, Unitelway, GEbus, Modbus, BitBus, PROFIBUS, PNET, CAN and other protocols. Its multi-mode equipment costs only a few hundred marks. It can be seen that the application of optical fiber communication in SCADA has reached a practical level.

How to build a good SCADA system, the choice of communication technology plays an important role. Nowadays, various communication technologies are developing rapidly, and public communication technologies have gradually established reliable and cheap platforms in the development of the market. SCADA system integrators must keep up with advanced technology in order to come up with the best communication solutions.

1.3. Control (Control) technology

The control equipment referred to in this article is the Slave of the SCADA system, or the lower computer, the remote terminal RTU and the on-site measurement and control intelligent device, or it can be a dedicated The RTU, intelligent instruments, intelligent controllers, and PLC systems are collectively referred to as lower-level control units. There are several control devices in every SCADA system, which have the greatest impact on the reliability and price of the SCADA system. In the past ten years, many models have been formed in the construction of water supply and drainage SCA DA systems, such as PC PLC model, PC microcontroller model, all imported PC RTU model, etc.

1.3.1. PC PLC mode

Here we only talk about the control part, that is, PLC. Each manufacturer and various types of PLC are a system platform for serialized products. A closed network has an open interface. In terms of control functions only, PLC is a technical product that is rigorous, convenient, easy to install, easy to program, and highly reliable. It provides high-quality hardware, a high-level system software platform and an easy-to-learn and understand application software platform (user platform), which is perfect for sequential logic control and many complex calculations. And the larger the scale, the more economical it is. In the water supply and drainage SCADA system, it has undisputed advantages in aspects such as tap water purification process control, sewage treatment process control, tap water secondary pump station multi-pump system control and remote water diversion multi-pump valve control. The shortcomings of PLC are also exposed in water supply and drainage SCADA. This is reflected in the high price of analog data collection, the high price of human-machine interface and the inability of small and medium-sized PLC data to realize the historical event recall (SOE) function. In water supply and drainage SCADA Applications in the system are restricted. In the SCADA dispatching system, it is unbearable to waste resources by using PLC to build a pressure measuring point terminal that only monitors one analog quantity. PC PLC should be used to build the SCADA system according to local conditions

1.3.2, PC microcontroller mode

Here we only talk about the control-related microcontroller (lower computer). For more than ten years, single-chip computers have been the mainstream in water supply and drainage SCADA systems. From Z80 single-board computer through 8031 ??and 8098, it has transitioned to the current mainstream single-chip computer of 80C196. Microcontrollers developed by various scientific research units and companies form the RTU of the SCADA system, and the target design model has never changed. In this way, the software of the microcontroller RTU adopts a closed approach of keeping secrets from each other (even within the same unit). This kind of closure not only causes the disadvantage of being difficult to maintain, but also destroys the resources of the microcontroller. It also causes the strange phenomenon that the RTU of the microcontroller is not cheap. It is reported that the price of each single-chip microcomputer device so far is thousands of yuan, while a single-chip microcomputer CPU only costs tens of yuan. Of course, compared with PLC and imported RTU, single-chip microcomputer is still the lowest price. The single-chip RTU is only suitable for pressure measuring point terminals, simple water source well control and data collection in simple environments. It should also be pointed out that the current RTUs made by domestic manufacturers using microcontrollers only support wired RS? 232, RS? 485 and wireless 200MHz communications. Few people consider the interface application issues of other high-efficiency communication protocols. So far, there is no commercialized single-chip RTU product designed according to the system platform suitable for water supply and drainage SCADA. ?For more than ten years, the wide application of single-chip RTU has trained a large number of application and maintenance personnel for SCADA users. These personnel are valuable resources for the development of water supply and drainage SCADA and are part of the water supply and drainage automation industry.

1.3.3. PC imported RTU mode

It is reported that one imported RTU completes the data monitoring of one pressure measuring point, and some costs as much as 60,000 yuan. This is a strange phenomenon. , without further comment.

1.3.4. Hybrid mode

Using PLC and microcontroller RTU to form a hybrid SCADA slave computer is the practice of most systems at present.

On-site measurement and control intelligent actuators

There are many types of on-site measurement and control intelligent actuators in SCADA systems.

Frequency control devices are most commonly used in water supply and drainage SCADA. This device plays a very good role in improving the water supply and drainage process, enhancing process controllability, and saving energy and reducing consumption. On-site measurement and control intelligence also includes pressure regulators, etc., which should be classified as sensing devices. On-site measurement and control intelligent devices are generally under the control of the Slave of the SC ADA system. Some communicate directly with the host PC to form a system.

Control technology is the key task of the SCADA system. So far, there is no standardized approach, let alone standardized products. When building a SCADA system specifically, it is mainly determined by the level, likes, dislikes and interests of the contractor and designer. In addition, the continuous development and update of technology is also one of the reasons for the lack of standardization and standardization. The standardization and standardization of the lower computer platform of the SCADA system is the key to building a high-quality and low-price SCADA system

1.4. Sensor technology

In the water supply and drainage SCADA system At the production site level, many sensors and actuators are installed to complete the production site data collection and control command execution of the SCADA system.

Sensors can be divided into two categories: intelligent and non-intelligent. The non-intelligent type completes the conversion of standardized electric power signals and the conversion of non-electrical physical and chemical data into standardized electric power signals. In addition to completing the work of the non-intelligent sensors mentioned above, intelligent sensors also have functions such as upper and lower limit alarm settings, data display, simple digital logic control, and PID adjustment. Most of the latest smart sensors have some kind of fieldbus function and can communicate with SCADA's upper PC or lower control unit to form a SCADA system. ?Commonly used sensors in water supply and drainage SCADA mainly include: water level, pressure, flow, temperature, humidity, turbidity, residual chlorine, BOD, COD, voltage, current, power, electricity, cosφ, flowing current meter and proximity switch, Limit switches, water level switches, relays, etc. ?In the past few years, domestic sensors generally failed to pass the test, and water supply and drainage SCADA sensors were still dominated by foreign sensor manufacturers.

Recently, a large number of domestically produced high-quality products have been launched in the water supply and drainage sensor market. It can be said that sensors are the highest and most successful link in SCADA localization.

Market Overview of Water Supply and Drainage Automation SCADA

The water supply and drainage automation market is composed of both supply and demand parties. The suppliers are mainly composed of SCADA system integration and related manufacturers, while the demanders are their respective water companies, sewage treatment plants and large factories, mines and government agencies related to water supply and drainage.

Demand-side market composition

There are more than 600 cities in my country. Each city has a water supply and drainage automation market, as well as hundreds of power stations and large-scale conglomerates and the vast majority of them. Townships and towns all constitute a vast water supply and drainage automation market. The demand side is the driving force of the market. The motivation for the demand side to purchase the water supply and drainage SCADA system is roughly as follows:

2.1.1. Legal reasons

(1) Water supply (tap water): There is the "Water Law" "Constraints must be met. The SCADA system is one of the important means to achieve water quality standards.

(2) Drainage: The country has formulated relevant laws and sewage must be discharged in compliance with standards, and the SCADA system is one of the important means to achieve discharge standards

2.1.2. Economic reasons

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A SCADA system with complete system design, careful and scientific equipment selection, good system integration, and reliable quality can bring good benefits to drainage SCADA buyers in terms of staff reduction, energy saving, consumption reduction, and strengthening management. Economic benefits.

2.1.3. Company image

Many users consider the company image when establishing SCADA systems.

2.1.4. Investor requirements

Nowadays, many water purification plants, sewage treatment plants and large-scale factories and mines are foreign-invested. There are SCADA systems in the original design, and they are required to be built by investors. SCADA system

2.2. Supply-side market composition Facing the vast demand-side market and complex demand-side purchasing reasons, a complex supply-side market is bound to emerge. Suppliers are the drivers and participants of market competition.

Supplier market rights are classified according to the primary market composed of equipment suppliers and the secondary market composed of system integrators

2.2.1. Primary market for SCADA equipment supply

Primary market The market includes computer and peripheral equipment hardware suppliers; computer and controller software equipment suppliers; communication equipment suppliers; control equipment suppliers (PLC, etc.); sensors and actuator suppliers; cable and chassis cabinet suppliers; electronic devices Suppliers; power suppliers, etc.

2.2.2. Secondary market composed of system integrators (automation engineering contractors)

(1) Professional agent integration of foreign SCADA systems;

(2) System integration engaged in system interconnection;

(3) Engineering contractors who develop software and hardware devices by scientific research institutions themselves;

(4) SCADA contracted by the demand-side users themselves System integration;

(5) Subcontractor.

Among the system integrators, there are many powerful and growing companies, and there are also many units that are just a bunch of people. The automation systems built by these integrators are very different and will not be reviewed here.

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