The smart energy meter is composed of a measurement unit, a data processing unit, and a communication unit. It is an energy meter with functions such as energy measurement, data processing, real-time monitoring, automatic control, and information interaction.
1. Classification of smart energy meters
Smart energy meters can be divided into single-phase meters and three-phase meters according to user types. According to different payment methods, it can be divided into local table and remote table.
Single-phase meters, as the name suggests, are energy meters used by ordinary users to measure 220V electricity. Three-phase meter, that is, the watt-hour meter used by the 380V electricity used in industry.
The local meter, that is, the electric energy meter that can be paid with an IC card on the user side. Remote tables, such tables are generally not installed in the user range. Users need to go to the power supply bureau to pay.
2. Step value and step interval of smart energy meter
A setting parameter of the ladder electricity price scheme, the ladder value is D and the unit is kWh, and the ladder interval is a range of electricity consumption, and the unit is kWh. When the number of step values is N, the power consumption range may be divided into N+1 step intervals.
3. Ladder price management scheme for smart energy meters
The tiered electricity price management plan includes determining the tiered value and the corresponding tiered electricity price. Example 1: A tiered electricity price scheme determines three tiered values of D1, D2, and D3 (unit: kWh). The four step intervals divided according to the three step values are W0, W1, W2, W3 and the corresponding four step electricity prices J0, J1, J2, J3 are determined. The ranges of each step interval are: 0≤W0≤D1, D1 .
4. The main functions of the smart energy meter
The user takes the IC card to the power supply department to pay for electricity purchase, and the power supply department uses the electricity sales management machine to write the purchased electricity into the IC card. The power supply can be closed, and the card can be taken away after power supply. When the remaining power in the meter is equal to the alarm power, the switch will turn on and the power will be cut off (or the buzzer will give an alarm). At this time, the user can swipe the card in the sensing area to return to normal. At this time, the user can swipe the card in the sensing area to restore the power supply; when the remaining power When it is zero, the power will be cut off automatically, and the user must pay a fee to purchase electricity with the card again before the electricity can be restored. Effectively solve the problem of door-to-door meter reading and electricity fee collection. At the same time, the user's electricity purchase information is managed by a microcomputer, which is convenient for query, statistics, charging and printing bills. It has the advantages of dual display, accurate measurement, stable precision, security and confidentiality, reliable performance, complete functions, low power consumption, and simple and convenient operation. There are also low-cost single-display energy meters.
5. Concept definition of smart energy meter
The concept of smart meters has been around since the 1990s. When the static meter first appeared in 1993, its price was 10 to 20 times that of the electromechanical meter, so it was mainly used in large users. Later, as the number of electricity meters with remote communication capabilities increased, it was urgent to develop new systems for meter reading and data management. In such systems, metering data is beginning to be opened up to systems such as distribution automation, but these systems are not yet capable of effectively utilizing the relevant data. Likewise, real-time energy consumption data from prepayment meters is rarely used for applications such as energy management or energy-saving measures.
With the advancement of technology, mass-produced static meters can obtain powerful data processing and storage capabilities at a very low cost, which has greatly improved the intelligence level of small consumer meters, and static meters have gradually replaced traditional electromechanical meters. electric meter.
For the understanding of smart energy meters, there is no unified concept in the world, and there is no unified international standard. Europe usually adopts the concept of "smart meter", while "smart electric meter" refers specifically to smart meters; the United States is accustomed to adopting the concept of "advanced meter", but the essence is the same. Although "smart meter" is translated as a smart meter or a smart meter, it mainly refers to a smart meter. Different organizations, research institutes and enterprises in the world have given different definitions of "smart meter" in combination with corresponding functional requirements.
6. Working principle of smart energy meter
A smart 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 the smart meter is: relying on the A/D converter or the metering chip to collect the user's current and voltage in real time, and analyze and process it through the CPU to realize the calculation of forward and reverse, peak and valley or four-quadrant electric energy, and further calculate the power and other content Output via communication, display, etc.
The composition and working principle of electronic smart meters are very different from traditional inductive meters.
Inductive meters are mainly composed of aluminum discs, current and voltage coils, permanent magnets and other components. The electronic smart meter is mainly composed of electronic components. Its working principle is to first sample the user's power supply voltage and current in real time, and then use a dedicated electric energy meter integrated circuit to process the sampled voltage and current signals and convert them into The pulse output proportional to the electric energy is finally processed and controlled by the single-chip microcomputer to display the pulse as power consumption and output it.
Usually we call the number of pulses sent by the A/D converter when the smart meter measures one kilowatt-hour of electricity as the pulse constant. For smart meters, this is a relatively important constant because the A/D converter The number of pulses sent will directly determine the measurement accuracy of the meter.
7. Classification of smart energy meters
Smart watt-hour meters can be roughly divided into two categories: electromechanical and all-electronic in structure.
Electromechanical integrated type, that is, add certain parts to the original mechanical meter so that it can not only complete the required functions, but also reduce the cost and be easy to install. On the basis of changing the national measurement standard, the sensor device is installed to become a smart meter with electric pulse output at the same time as the mechanical measurement, so that the electronic counting and mechanical counting are synchronized, and its measurement accuracy is generally not lower than that of the mechanical counting meter. Degree meter. This design scheme adopts the mature technology of the original induction watch, and is mostly used for the transformation of old watches.
7.2 Fully electronic
The all-electronic type adopts electronic devices with integrated circuits as the core from measurement to data processing, thus eliminating the long-term use of mechanical parts on the meter. Compared with the electromechanical integrated meter, the meter has a smaller volume, increased reliability, and is more accurate. , The power consumption is reduced, and the production process is greatly improved. It does not have to be produced in a professional meter factory in the original sense, and will eventually replace the meter with mechanical parts.
8. Main applications of smart energy meters
8.1 Billing and accounting
Accurate and real-time fee settlement information processing can be realized through smart meters, which simplifies the complicated process of accounting processing in the past. In the electricity market environment, dispatchers can switch energy retailers more timely and conveniently, and even fully automatic switching can be achieved in the future. At the same time, users can also obtain more accurate and timely energy consumption information and accounting information.
8.2 Distribution Network State Estimation
The power flow distribution information on the distribution network side is inaccurate, mainly because the information is comprehensively processed based on the network model, load estimates, and measurement information on the high-voltage side of the substation. By adding measurement nodes on the user side, more accurate load and network loss information will be obtained, thereby avoiding overload of power equipment and deterioration of power quality. By integrating a large amount of measurement data, the prediction of the unknown state and the verification of the accuracy of the measurement data can be realized.
8.3 Power quality and power supply reliability monitoring
The use of smart meters can monitor the power quality and power supply status in real time, so as to respond to user complaints in a timely and accurate manner, and take measures in advance to prevent the occurrence of power quality problems. There are gaps in the real-time and effectiveness of the traditional power quality analysis methods.
8.4 Load analysis, modeling and forecasting
Water, gas, and heat energy consumption data collected by smart meters can be used for load analysis and forecasting. By comprehensively analyzing the above information, load characteristics, and time changes, the total energy consumption and peak demand can be estimated and predicted. This information will provide convenience to users, energy retailers and distribution network dispatchers, promote rational electricity consumption, energy saving and consumption reduction, and optimize power grid planning and dispatching.
8.5 Power Demand Side Response
Demand-side response means controlling user load and distributed generation through electricity prices. It includes price control and load direct control. Price control generally includes time-of-use electricity prices, real-time electricity prices, and emergency peak electricity prices to meet the needs of regular electricity, short-term electricity, and peak electricity consumption, respectively. In direct load control, the network dispatcher usually realizes the connection and disconnection of loads through remote commands according to network conditions.
8.6 Energy Efficiency Monitoring and Management
By feeding back the energy consumption information provided by the smart meter to the user, the user can be prompted to reduce energy consumption or change the way of energy utilization. For families equipped with distributed power generation equipment, it can also provide users with reasonable power generation and power consumption schemes to maximize the benefits of users.
8.7 User energy management
Through the information provided by the smart meter, a user energy management system can be built on it, so as to provide energy management services for different users (residential users, commercial users, industrial users, etc.), and meet the indoor environment control (temperature, humidity, lighting, etc. ) while reducing energy consumption as much as possible to achieve the goal of reducing emissions.
8.8 Energy saving
Provide users with real-time energy consumption data, promote users to adjust their electricity consumption habits, and detect abnormal energy consumption caused by equipment failures in a timely manner. 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-of-use network electricity prices, electricity contracts with repurchase, spot price electricity contract etc.
8.9 Smart Home
Smart home refers to the connection of different devices, machines and other energy-consuming equipment in the home in a network, and controls according to the needs and behavior of residents, outdoor temperature and other parameters. It can realize the interconnection of heating, alarm, lighting, ventilation and other systems, so as to realize the remote control of home automation and home appliances and other equipment.
8.10 Preventive maintenance and failure analysis
The measurement function of smart meters helps to realize the preventive maintenance of distribution network components, energy meters, and user equipment, such as detecting voltage waveform distortion, harmonics, and imbalances caused by power electronic equipment failures and ground faults. The measurement data can also help the grid and users analyze grid component failures and network losses.
Compared with the traditional prepayment method, the smart meter can provide a lower cost, more flexible and friendly prepayment method.
8.12 Meter Management
Meter management includes: asset management of installed meters; maintenance of meter information database; regular access to meters; ensuring the normal installation and operation of meters; confirming the location of meter storage and correctness of user information, etc.
8.13 Load remote control
The overall connection and disconnection of the load can be realized through the smart meter, and some users can also be controlled, so as to cooperate with the dispatching department to realize power control; at the same time, the user can also realize the remote control of the specific load through the controllable switch.
8.14 Detection of illegal electricity usage
The smart meter can detect events such as the opening of the meter box, the change of the wiring, and the update of the meter software, so as to detect electricity theft in time. For areas with a high incidence of electricity theft, potential electricity theft can also be detected in time by comparing the data of the master meter with the data of all the meters below it.
Smart meters can provide users with value-added services such as grid faults, power outages, power quality, energy consumption, energy efficiency information, and recommended power consumption schemes, which improves the competition and efficiency of the energy market, and provides a solution for applications such as frequency, voltage, and reactive power control. Technical conditions.