Smart electricity meter is one of the basic equipment for data acquisition of smart power grid (especially smart power distribution network). It undertakes the tasks of data acquisition, measurement and transmission of original electric power, and is the basis for information integration, analysis and optimization and information presentation. In addition to the measuring function of basic electricity consumption of traditional electricity meters, smart electricity meters also have the functions of two-way metering of various rates, user control function, two-way data communication function of various data transmission modes, anti-power theft function and other intelligent functions to adapt to the use of smart power grids and new energy.
The advanced Metering Infrastructure (AMI) and Automatic Meter Reading (AMR) system built on the basis of smart electricity metering can provide users with more detailed electricity consumption information, enabling them to better manage their electricity consumption to achieve the goal of saving electricity and reducing greenhouse gas emissions. Electricity retailers can flexibly set TOU price according to the demand of users to promote the reform of electricity market price system. Distribution companies can detect faults more quickly and respond in a timely manner to strengthen power network control and management.
The basic equipment of power and energy, raw electric energy data collection, measurement and transmission have high reliability, high accuracy and low power consumption, etc
The concept of the Smart Meter traces back to the 1990s. When static electricity meters first appeared in 1993, they were 10 to 20 times more expensive than electromechanical meters, so they were mainly used by large users. With the increase of the number of electricity meters with telecommunication capability, it is necessary to develop a new system to realize meter reading and data management. In such systems, metering data begins to be opened up to systems such as distribution automation, but these systems are not yet able to make effective use of the relevant data. Similarly, real-time energy consumption data from prepaid meters are rarely used in applications such as energy management or energy conservation measures.
With the progress of technology, mass produced static electricity meters can acquire powerful data processing and storage capacity at a very low cost, thus promoting the intelligent level of small users’ electricity meters to be greatly improved, and the static electricity meters have gradually replaced the traditional electromechanical electricity meters.
For the understanding of “Smart Meter”, there is no unified concept or international standard in the world. The concept of smart Electric Meter is usually adopted in Europe, while the term smart Electric Meter refers to smart electricity meters. In the United States, the concept of Advanced Meter was used, but the substance was the same. Although smart meter is translated as smart meter or smart meter, it mainly refers to smart electricity meter. Different international organizations, research institutions and enterprises have given different definitions of “Smart Meter” in combination with corresponding functional requirements.
ESMA
The European Smart Metering Alliance (ESMA) describes Metering characteristics to define Smart electricity meters.
(1) Automatic processing, transmission, management and use of measurement data;
(2) Automatic management of electricity meters;
(3) Two-way communication between electricity meters;
(4) Provide timely and valuable energy consumption information to relevant participants (including energy consumers) within the smart metering system;
(5) Support the improvement of energy efficiency and the services of energy management systems (generation, transmission, distribution, and use).
South Africa’s Eskom Power Company
Compared with traditional meters, smart meters can provide more consumption information, which can be sent to local servers through a specific network at any time to achieve the purpose of metering and billing management. It also includes:
(1) A variety of advanced technologies are integrated;
(2) Real-time or quasi-real-time meter reading;
(3) Detailed load characteristics;
(4) Power outage record;
(5) Power quality monitoring.
DRAM
According to the Demand Response and Advanced Metering Coalition (DRAM), smart electricity meters should be able to achieve the following functions:
(1) Measure energy use data in different time periods, including hourly or authoritative time periods;
(2) Allowing power consumers, power companies and service agencies to trade power at various prices;
(3) Provide other data and functions to improve power service quality and solve problems in service.
Working principle
Smart electricity meter is an advanced metering device that collects, analyzes and manages electric energy information data based on modern communication technology, computer technology and measurement technology. The basic principle of smart electricity meter is: rely on A/D converter or metering chip to carry out real-time collection of user’s current and voltage, carry out analysis and processing through CPU, realize the calculation of positive and negative direction, peak valley or four-quadrant electric energy, and further output the content of electricity through communication, display and other means.
The structure and working principle of smart electricity meter are very different from the traditional induction electricity meter.
Induction type ammeter is mainly composed of aluminum plate, current voltage coil, permanent magnet and other elements. Its working principle is mainly through the current coil and movable lead plate
Composition of smart electricity meters
Measured by the induced eddy current interaction, electronic smart meter is mainly composed of electronic components and its working principle is based on the user power supply voltage and current real time sampling, again USES the dedicated watt-hour meter integrated circuit, the sampled voltage and current signal processing, translates into is proportional to the power of the pulse output, finally controlled by single chip microcomputer for processing, the pulse display for power consumption and output.
Usually, we call the number of pulses emitted by A/D converter when measuring one degree of electricity in A smart meter as the pulse constant. For A smart meter, this is A relatively important constant, because the number of pulses emitted by A/D converter per unit time will directly determine the measurement accuracy of the meter.
In terms of structure, the smart watt-hour meter can be roughly divided into two categories: electromechanical integrated meter and all-electronic meter.
Electromechanical integration
Electromechanical one-piece, namely in the original mechanical meter attached to certain parts of the already complete the required functions, and reduce cost and easy to install, its design scheme is generally without destroying current meter physical structure, without changing the original on the basis of its national measurement standard, adding sensing device into the mechanical meter degrees at the same time also have electrical pulse output, synchronize the electronic numeration and mechanical numeration. Its measuring accuracy is not lower than general mechanical meter type meter. This design scheme adopts the mature technology of the original induction type table, which is mainly used for the reconstruction of the old meter.
Feature
(1) Reliability
The accuracy is unchanged for a long time, no wheel alignment, no installation and transportation effects, etc.
(2) Accuracy
Wide range, wide power factor, start sensitive, etc.
(3) Function
It can implement the functions of centralized meter reading, multi-rate, pre-payment, preventing power theft, and meeting the requirements of Internet access services.
(4) Cost performance
High cost performance can be reserved for expansion functions, affected by the price of raw materials.
(5) Alarm prompt
When the remaining electric quantity is less than the alarm electric quantity, the meter often shows the remaining electric quantity to remind the user to purchase electricity. When the remaining power in the meter is equal to the alarm power, the tripping power is cut off once, the user needs to insert IC card to restore power supply, the user should timely purchase power at this time.
(6) Data protection
All-solid-state integrated circuit technology is adopted for data protection, and data can be maintained for more than 10 years after power failure.
(7) Automatic power off
When the remaining quantity of electricity in the electricity meter is zero, the meter will trip automatically and interrupt the power supply. At this time, the user should timely purchase electricity.
(8) Write back function
The power card can write the accumulative power consumption, residual power and zero-crossing power back to the electricity selling system for the convenience of the management department’s statistical management.
(9) User sampling inspection function
Electricity sales software can provide data sampling inspection of electricity consumption and provide priority sampling of user sequences as required.
(10) Power query
Insert IC card to show the total power purchased, the number of power purchased, the last power purchased, the cumulative power consumption and the remaining power.
(11) Overvoltage protection
When the actual load exceeds the set value, the meter will automatically cut off power, insert the customer card, and restore power supply.
Main Applications
(1) Settlement and accounting
The intelligent electricity meter can realize accurate and real-time cost settlement information processing, which simplifies the complex process of account processing in the past. In the power market ring
The power quality
Under the environment, dispatchers can switch energy retailers in a more timely and convenient manner, and even realize automatic switching in the future. At the same time, users can also get more accurate and timely energy consumption information and accounting information.
(2) Distribution network state estimation
The power flow distribution information on the distribution network side is not accurate, mainly because the information is obtained by the comprehensive processing of network model, load estimation value and measurement information on the high-voltage side of substation. By adding measurement nodes on the user side, more accurate load and network loss information will be obtained, thus avoiding overload and power quality deterioration of power equipment. By integrating a large number of measurement data, the estimation of unknown state can be realized and the accuracy of measurement data can be checked.
(3) Power quality and power supply reliability monitoring
Intelligent electricity meters can monitor power quality and power supply condition in real time, so as to respond to users’ complaints timely and accurately, and take measures in advance to prevent power quality problems. The traditional power quality analysis method has a gap in real time and effectiveness.
(4) Load analysis, modeling and prediction
The data of water, gas and heat energy consumption collected by smart electricity meters can be used for load analysis and prediction. By comprehensively analyzing the above information with load characteristics and time changes, the total energy consumption and peak demand can be estimated and predicted. This information will facilitate users, energy retailers and distribution network operators to promote rational use of electricity, save energy and reduce consumption, and optimize grid planning and scheduling.
(5) Power demand side response
Demand-side response means controlling user loads and distributed generation through electricity prices. It includes price control and direct load control. Price controls generally include time-of-use, real-time and emergency peak rates to meet regular, short-term and peak demand, respectively. Direct load control is usually achieved by the network dispatcher according to the network condition through remote command to access and disconnect the load.
(6) Energy efficiency monitoring and management
By feeding back information about energy use from smart meters, users can be encouraged to reduce their energy consumption or change the way they use it. For households equipped with distributed generation equipment, it can also provide users with reasonable power generation and power consumption schemes to maximize the benefits of users.
(7) User energy management
By providing information, smart meters can be build on the energy management system of the user, for different users (residents users, commercial and industrial users, etc.) to provide energy management services, in the indoor environment control (temperature, humidity, lighting, etc.) at the same time, as far as possible to reduce energy consumption, realize the goals to reduce emissions.
(8) Energy saving
Provide users with real-time energy consumption data, promote users to adjust their power consumption habits, and timely find abnormal energy consumption caused by equipment failure. Based on the technology provided by smart meters, power companies, equipment suppliers and other market participants can provide users with new products and services, such as different types of time-sharing network electricity prices, electricity contracts with buy-back, spot price electricity contracts, etc.
(9) Intelligent family
Smart home refers to the connection of different devices, machines and other energy-consuming equipment in the home in a network, and according to the needs and behaviors of residents, outdoor
It can realize the interconnection of heating, alarm, lighting, ventilation and other systems, so as to realize the remote control of home automation and appliances and other equipment.
(10) Preventive maintenance and fault analysis
The measurement function of smart electricity meters helps to realize the prevention and maintenance of distribution network components, electricity meters and user equipment, such as detecting voltage waveform distortion, harmonic, imbalance and other phenomena caused by power electronic equipment faults and ground faults. The measurement data can also help the grid and users analyze grid component failures and losses.
(11) Payment in advance
Smart meters offer a lower cost, more flexible and friendly prepaid method than traditional prepaid methods.
(12) Management of electricity meters
Meter management includes: asset management of installation meter; Maintenance of information database; Periodic access to the meter; Ensure the proper installation and operation of the meter; Verify the location of meters and the correctness of user information, etc.
Post time: Aug-20-2020