Remote meter reading system

¡¡¡¡Remote meter reading refers to a system that uses microelectronics, computer network, sensing and other technologies to automatically read and process meter data and comprehensively process the water, electricity and gas information of urban residents. Automatic meter reading technology enables water, electricity and gas companies and property management departments to fundamentally solve the troubles caused by meter reading fees to users and meter readers, and avoid many unnecessary disputes. An accurate and convenient charging system can not only improve the work efficiency of the management department, but also meet the needs of modern users for water, electricity and gas payment.

¡¡¡¡Schematic diagram of remote automatic meter reading system

¡¡¡¡1¡¢ Overview of remote automatic meter reading system

¡¡¡¡At present, the most common remote automatic meter reading system adopts the centralized meter reading mode of split line system, that is, the water, electricity and gas meter signals from multi-channel split line connection are collected by the collector regularly and sequentially for data processing and storage. The collectors are connected by bus system and finally connected to the computer. Its typical feature is that each household meter is connected to the collector through household line. The system is generally divided into four levels; On site collector, server (area manager), communication controller, manager center, and some products will also be attached with a handheld reader. The system structure is shown in the figure below:

¡¡¡¡1. Field acquisition instrument: complete the acquisition of the output data of the field meter. Generally, one collector can collect multiple base meters. However, at present, there are not many products that support one collector to collect several different types of base tables at the same time.

¡¡¡¡2. Server (area manager): collect the table data in the data collector by multi computer communication, then process and store it, and connect it with the computer of the system management center in the general control room through the communication bus. A server can connect dozens of data collectors (depending on the communication mode of the system).

¡¡¡¡3. Communication controller: connect the computer between the server and the management center to convert the signal.

¡¡¡¡4. Management Center: the management center is composed of multimedia computer and system management software. Installed at the property management center. You can connect to the marketing system through excuses. With the help of Internet technology, the computer of the management center can be connected with the network of power, water, gas or other toll collection departments to realize online reading. Online users can query their own expenses online, which is convenient and practical, and can be extended to e-commerce to realize online payment.

¡¡¡¡2¡¢ Power remote meter reading

¡¡¡¡1. Current table end data acquisition method

¡¡¡¡People know that to convert a mechanical meter into a digital meter, the angle of mechanical rotation (angular displacement) must be converted into a countable signal. The original conversion was to use mechanical contact switches to form pulses. In the 1980s, photoelectric technology was gradually popularized and widely used. In the primary stage of meter reading system, photodiodes and photosensitive triodes are mostly used, including visible light and infrared light. Their application modes are penetrating and reflective. Photoelectric direct reading is one of the modes of reading meter end data in recent years. Its basic principle is to encode the word wheel according to the angle and read out the number of the position of the word wheel through photoelectric. The biggest advantage of photoelectric direct reading is that it does not have to supply power for a long time. It can only supply power when reading data. However, its structure is complex and easy to be polluted by water, oil and gas, resulting in inaccurate meter reading data. The most important problem at the meter end is to solve the problem that the signal increment must maintain a one-to-one correspondence with the mechanical rotation, which is very reliable. It is precisely because each manufacturer of automatic meter reading system has different solutions to the meter end, and the response effect in the market is naturally different.

¡¡¡¡2. Problems caused by signal transmission

¡¡¡¡There are many ways of signal transmission, wired and wireless. In each mode, its topology and communication protocol directly affect its communication quality. According to the current technological development level, the vast majority of remote meter reading systems adopt wired mode, or some wired mode. The initial construction investment of wired mode is large and the project is difficult, but the communication quality is good. However, due to the increase of high-rise buildings and high-end houses in recent years, the wiring work is facing new problems. In addition to the engineering difficulties, it is difficult to solve the user satisfaction, especially for the existing users, it is difficult to achieve household satisfaction if they want to drill holes in the indoor wall. Wiring in the residential area will also affect the cultural landscape of the residential area. In general, the property management and owners of the residential area are not allowed to break the ground or set up wires in the air.

¡¡¡¡Wireless transmission communication has developed rapidly in recent years, especially after the opening of 433MHz frequency band, many manufacturers have introduced this technical advantage into the automatic meter reading system, and some enterprises have even directly introduced the finished module integrated with data acquisition and transmission in western developed countries, but it involves many problems such as signal link and networking, which is not ideal, Promotion is difficult to continue.

¡¡¡¡GPRS technology is a hot spot in the current automatic meter reading system. Its advantage is that it borrows the ready-made communication platform of China mobile communication and does not need users to maintain and manage themselves. However, there are many manufacturers of GPRS communication equipment. Although some systems choose GPRS, they do not choose a GPRS with excellent performance, or the GPRS parameter setting does not reach the best state, which makes the data transmission quality and efficiency low, and directly affects the working efficiency of the automatic meter reading system.

¡¡¡¡3. Further optimize the system platform

¡¡¡¡The central control software and working platform are the core of the automatic meter reading system. It determines whether the system platform is efficient, reliable and freely applied. Over the past ten years, the automatic meter reading system has made great progress through the promotion of scientific research institutions and enterprises and the efforts of engineers and technicians. The new automatic meter reading system scheme has been mature and has been gradually popularized and applied in the market.

¡¡¡¡3¡¢ GPRS Remote Automatic Meter Reading

¡¡¡¡1. System overview

¡¡¡¡GPRS meter remote meter reading system consists of watt hour meter, collector with GPRS communication module and server. The collector collects the user's power consumption data in real time and collects the data to the server through GPRS. It has the characteristics of fast and accurate data collection, rapid generation of power consumption statistics and analysis, payment documents and so on. Compared with the traditional manual meter reading and telephone line meter reading, it greatly improves the efficiency. In addition to accurate and real-time meter reading, the system also provides equipment management functions, such as alarm: unpacking alarm, power failure alarm, reverse phase alarm, overtemperature alarm, overload alarm, etc; Control: switch off the arrearage users. It also provides power failure data protection function, and can still read and monitor meters within 48-72 hours of power failure. The system can be combined with the SMS platform of the mobile company. In case of alarm, the system can send SMS to relevant managers according to the specific content.

¡¡¡¡2. System composition

¡¡¡¡The system can be composed of master station with system software, collector with GPRS module and watt hour meter. The handheld terminal is the supplement of the system, and manual meter reading is carried out in case of accidents in the system.

¡¡¡¡Master station: the computer (server or PC) running the centralized meter reading system is called the master station, which is connected with the collector through GPRS network. The master station shall be configured with a fixed IP address and Internet outlet.

¡¡¡¡Collector with GPRS module: collect electricity meter data and transmit it to the data center, which connects the master station and the electricity meter.

¡¡¡¡Watt hour meter: measure and display the power consumption of users, and transmit the power consumption information to GPRS collector.

¡¡¡¡These three main components are interrelated master-slave relationships.

¡¡¡¡3. Meter reading mode

¡¡¡¡3.1 meter reading system for resident users

¡¡¡¡1. Watt hour meter: single-phase static (Electronic) watt hour meter with optocoupler pulse output function.

¡¡¡¡2. Collector with GPRS function (GPRS-DTU with built-in saro-3130p):

¡¡¡¡(1) 24 I / O ports, with 24 household watt hour meters

¡¡¡¡(2) Power failure data protection

¡¡¡¡(3) With backup power supply, meter reading can still be carried out after power failure

¡¡¡¡3. Meter reading content: electricity and others

¡¡¡¡4. Meter reading form: (1) automatic meter reading (2) regular reporting (3) real-time query

¡¡¡¡5. Alarm contents: (1) unpacking alarm (2) power failure alarm

¡¡¡¡The remote control switching function can be added, and the built-in relay shall be added to the electric energy meter.

¡¡¡¡3.2 meter reading system for large group users

1. Electricity meter: a) three-phase active and reactive multi-function meter, active 0.5 and reactive 2, with RS-485 communication interface and DL / T645 communication protocol of the Ministry of electric power. Or use: b) three phase active power multiple rate table, active power level 1, with RS-485 communication interface and DL / T645 communication protocol of the Ministry of electric power. Realize the measurement of electric energy (active and reactive) and the measurement of power factor, voltage, current, frequency and other parameters.

   
   

¡¡¡¡2. Collector with GPRS function:

¡¡¡¡(1) With one RS-485 interface for communication with the electric energy meter, one GPRS interface for communication with the main station system, three switching value input ports for alarm monitoring and three analog value output ports for remote control.

¡¡¡¡(2) Support ministry standard communication protocol

¡¡¡¡(3) Power failure data protection

¡¡¡¡(4) Control output (for remote control switching or other functions)

¡¡¡¡(5) With backup power supply, meter reading can still be carried out after power failure

¡¡¡¡3. System function

¡¡¡¡(1) Set the parameters of the electric energy meter and read various metering and management data;

¡¡¡¡(2) Statistics, query, backup, report and chart generation of meter reading data;

¡¡¡¡(3) Plant and station management;

¡¡¡¡(4) Automatic meter reading, regular reporting, real-time query, etc;

¡¡¡¡(5) Power down data storage;

¡¡¡¡(6) Comprehensive processing of instantaneous data;

¡¡¡¡(7) System data backup, archiving and export data;

¡¡¡¡(8) Historical data event recording function;

¡¡¡¡(9) Real time alarm;

¡¡¡¡(10) Calculate the line loss according to the meter relationship on the line;

¡¡¡¡(11) It can provide multi-channel analog quantity and switching value input to realize other functions such as unpacking alarm, power failure alarm, reverse phase alarm, overtemperature alarm, overvoltage alarm, overcurrent alarm, overload alarm, tilt or movement alarm;

¡¡¡¡(12) Remote control power-off function;

¡¡¡¡(13) Collected parameters, such as:

¡¡¡¡¡ô current, last month, forward active, reverse active and reactive quadrant total and peak, peak, average and valley electricity rates;

¡¡¡¡¡ô maximum demand and occurrence time of forward, reverse, active and reactive power;

¡¡¡¡¡ô active power, reactive power, three-phase voltage, three-phase current and power factor;

¡¡¡¡¡ô feel the cumulative times of voltage loss, cumulative time of voltage loss, starting and ending time of power failure of centralized reading device, etc;

¡¡¡¡¡ô unit time load curve, three-phase current curve, three-phase voltage curve, active power curve, reactive power curve and power factor curve.

¡¡¡¡3.3 substation meter reading system

¡¡¡¡1. Electricity meter: three-phase active and reactive multi-function meter.

¡¡¡¡2. Collector with GPRS function:

¡¡¡¡(1) With one 485 port, three switching values and three analog values;

¡¡¡¡(2) Support ministry standard communication protocol;

¡¡¡¡(3) Power failure data protection;

¡¡¡¡(4) Control output;

¡¡¡¡(5) With backup power supply, meter reading can still be carried out after power failure.

¡¡¡¡3. Meter reading content:

¡¡¡¡(1) Voltage and current;

¡¡¡¡(2) Positive and negative time-sharing electric quantity of active power; Reactive four quadrant time-sharing electric quantity;

¡¡¡¡(3) Maximum demand and occurrence time of active power forward and reverse time sharing;

¡¡¡¡(4) Maximum demand and occurrence time of reactive power forward and reverse time sharing;

¡¡¡¡(5) Phase failure time, times and power consumption during phase failure;

¡¡¡¡(6) Load curve.

¡¡¡¡4. Meter reading form:

¡¡¡¡(1) Automatic meter reading;

¡¡¡¡(2) Report regularly;

¡¡¡¡(3) Real time query.

¡¡¡¡5. Alarm content:

¡¡¡¡(1) Unpacking alarm;

¡¡¡¡(2) Power failure alarm;

¡¡¡¡(3) Reverse phase alarm;

¡¡¡¡(4) Overtemperature alarm;

¡¡¡¡(5) Overvoltage alarm;

¡¡¡¡(6) Overcurrent alarm;

¡¡¡¡(7) Overload alarm;

¡¡¡¡(8) Other functions such as tilt or movement alarm.

¡¡¡¡4¡¢ Functions and characteristics of the system

¡¡¡¡(1) Security and reliability: security consists of three aspects: first, Oracle database is a large and multi-user database. It has high security. It allows multiple users to use the same database at the same time without damaging the integrity. Using it as the data engine of meter reading system can ensure the security of data; Second, the system realizes the hierarchical authorization management function for users, endows users with corresponding operation rights by checking the user's name and authorized password, and uses the password management mode of the banking system for reference to restrict irrelevant personnel from changing the database and hardware settings. Third, the firewall function and perfect data backup function prevent the system from being attacked by man-made malicious attacks. The data backup function ensures that the meter reading system can be started without data loss on new hardware equipment at any time in case of hardware system failure.

¡¡¡¡(2) Perfect system log: the system log records the operation of entering the system, leaving the system, charging, setting hardware, changing operation parameters, operators and operation time. All operations that change the database are recorded.

¡¡¡¡(3) Fast meter reading speed: the meter reading is fast and the data is accurate. During meter reading, the PC reads only the data from the collector. The data transmission adopts 1200 baud rate, the transmission speed is fast, and each data block is effectively checked to ensure the accuracy of transmission.

¡¡¡¡(4) Broadcast timing function: this function makes the time benchmark of all electric energy meters in the system consistent with the PC. after the timing is successful, the internal clock of the electric energy meter powered by the battery does not need the intervention of the PC. Therefore, as long as it is ensured that the time of PC is correct at the time of time synchronization, changing the clock of PC will not affect the time of electric energy meter in the process of operation in the future.

¡¡¡¡(5) Automatic meter reading function: according to the set meter reading start time and meter reading interval, to the predetermined meter reading time, the system will dial in turn to copy the data in the collector or meter. If the data cannot be copied, the system will automatically copy or manually send a command to copy.

¡¡¡¡(6) Electricity freezing function: it is convenient to define the general table, install and delete the general table, and assign sub tables to the general table. By installing an appropriate master meter and combining the function of reading and freezing data, the reading of the master meter at a specific time can be obtained, and the reading of each sub meter (from which the reading sum can be obtained), the power loss of a certain part of the circuit can be calculated, so as to provide a basis for determining the power charge.

¡¡¡¡(7) Electricity charge management function: uniformly copy the electricity charge data before collecting the electricity charge. When the data of electricity consumption in the database and the latest electricity consumption in the database are automatically reflected by the program. When paying the electricity fee, you only need to enter the user number, and the electricity consumption and electricity fee of the current month shall be filled in by the program. There are detailed records for each electricity charge, which is convenient for reconciliation.

¡¡¡¡(8) Equipment management functions, such as alarm: unpacking alarm, power failure alarm, reverse phase alarm, overtemperature alarm, overload alarm, tilt or movement alarm, etc; Control: switch off the arrearage users. It also provides power failure data protection function, and can still read and monitor meters within 48-72 hours of power failure. Combined with the short message platform of mobile company, this system can send short messages to relevant managers according to specific contents in case of alarm.

¡¡¡¡5¡¢ Summary

¡¡¡¡For the power sector, remote meter reading has always been a headache, which requires a lot of human, material and financial resources. Because of the large number and scattered geographical location, it brings great inconvenience to the staff. Nowadays, power companies can use GPRS mobile data network to monitor important power nodes and large user meters, automatically read and analyze relevant data, and further carry out remote control or equipment maintenance, which can reduce human resources, shorten repair time and save special line construction cost.