Keywords: power meter, energy management system, building energy saving measurement
0 Introduction At present, according to the statistics of the relevant state departments, the average annual power consumption per square meter of construction area of ​​office buildings and large public buildings of the state organs is 85.4 degrees (annual average 85.4kWh / m2), accounting for about 22 %, The power consumption per square meter is 10 to 20 times that of ordinary residents, and 1.5 to 2 times that of similar buildings in developed countries such as Europe and Japan.
On the one hand, China's large public buildings use huge amounts of electricity. On the other hand, we also lack direct data to provide reference for making energy-saving energy-saving decisions. To this end, the Jiangsu Provincial Department of Construction formulated and issued Su Jianke [2007] No. 217 "Regulations on Energy Measurement Design for Public Buildings in Jiangsu Province" to strengthen the energy-saving operation management of public buildings and decompose the work objectives and tasks of energy-saving and emission reduction in stages Implement, establish an energy-saving supervision system and a long-term energy use inspection and assessment mechanism, and improve energy use measurement design.
New construction, reconstruction and expansion of public building projects with a unit of more than 20,000 m2 should implement the relevant national and provincial standards and regulations when reviewing the design and construction drawings.
The energy metering device in the building should use products with remote transmission function, which is convenient for setting up the management system and networking with the BA system.
Electricity plays an increasingly important role in daily production and life, accounting for most of the energy consumption. Therefore, the implementation of energy metering management in large-scale public buildings can promptly find and correct waste of electricity consumption and provide data for energy-saving assessment of buildings.
1 Selection of power meters in building energy conservation metering Large-scale public building energy metering should use power meters as internal management meters. Power meters are installed on the basis of users installing toll meters, considering the need for internal energy metering and energy-saving management. Statistics and management of electrical energy in buildings. Therefore, users can choose to purchase independently, but should pay attention to whether the manufacturer has a measurement license for power meters (electric energy part). The electric power meter can complete the collection of electric energy data of each circuit, each floor or each functional area, and complete the electric power monitoring and electric energy metering management of large public buildings through the background electric energy management system.
Power meters are designed for power monitoring and power management needs of power systems, industrial and mining enterprises, public facilities, and intelligent large public buildings. It can measure all commonly used power parameters with high precision, such as three-phase voltage, three-phase current, active power, reactive power, frequency, power factor, four-quadrant energy, etc., and uses high visibility LCD to display the instrument measurement parameters And the operating information of the power grid system. There are many functions and models of power meters, the prices are also different, and there are many kinds of energy metering schemes. Therefore, they should be reasonably selected to achieve better cost performance.
According to Su Jianke [2007] No. 217 document, the energy consumption data of large-scale public buildings are classified and measured, and the electrical energy is divided into measurement and management according to power consumption, lighting and socket consumption, air conditioning consumption and special consumption. Therefore, for dormitory, shops, hotel rooms and other places that should be measured to economic accounting units, DDS1352 or DDSF1352 electric meters can be used;
DDS1352 single-phase electric meter, also known as ADL10; single-phase electric energy meter, DIN35mm rail installation, width is 1 module (that is, width is 18mm), maximum single-phase current 30A, accuracy level 1.0. The instrument is small in size and low in price. The disadvantage is that it has no communication function and cannot be networked.
DDSF1352 single-phase electric meter, also known as ADL100, is also installed on DIN35mm guide rail, width is 4 modules, maximum single-phase current is 80A at one time, accuracy is 1.0, with peak, flat and valley energy time-sharing rate measurement Function, with RS485 interface, Modbus communication protocol or DL ​​/ T645 protocol, can be networked. It is mainly used for the measurement of single-phase electrical energy and is commonly used in distribution boxes. The appearance and application of DDS1352 and DDSF1352 single-phase electric meters are shown in Figure 1:
Figure 1 DDS1352 meter appearance, DDSF1352 meter appearance and its application
For electricity facilities, the metering is based on Ming and socket, power, air conditioning, and special electricity. When measuring classrooms, medical wards, and hotel rooms by floor or functional division, DTSF1352 or ACR120EL meters can be used. .
Adopt DTSF1352 three-phase four-wire electric meter (see Figure 2), also known as ADL300, used for three-phase electric energy measurement, with time, peak, flat and valley electric energy time-sharing rate measurement function, DIN35mm guide rail installation, width is 7 modules It can be installed in the lighting box or power box. The maximum three-phase current is 80A at a time. Above 80A can be accessed through the current transformer for a second time. The accuracy is 0.5. With RS485 interface, Modbus communication protocol or DL ​​/ T645 communication protocol , Can be networked [1].
The ADL series rail-mounted energy meters can be easily installed on the rails on the back of the power distribution cabinet (box) without opening the panel. This one-to-one measurement is very clear and convenient for system maintenance of.
Figure 2 DTSF1352 electric meter shape and its application in power box
ACR120EL multi-function electric meter is adopted, which is embedded installation and can be installed on the door panel of the power box or low-voltage outlet cabinet. The panel size is 80mm × 80mm, the specification is 220 / 380V, 5A, and the current is accessed through the transformer for the second time. 0.5 level, can measure electrical parameters such as current, voltage, power, frequency, power factor, four-quadrant energy, with RS485 interface, Modbus communication protocol.
For some important occasions where the harmonic content needs to be detected, the ACR230ELH multi-function meter can be used. Su Jianke [2007] 217 stipulates that important feeder and feeder circuits, such as elevators, pumps, fans, kitchen equipment, parking equipment, etc., have different functions. The equipment shall be measured separately according to the main line. The front-end equipment of the air-conditioning system is measured according to the main line system, and the end of the air-conditioning and the air-conditioning outlet should be measured according to the floor or partition. When there is an economic accounting unit in the building and a central air conditioner is used, an electric energy meter shall be provided separately at the end of the air conditioner in the area. Therefore, the ACR230ELH multi-function meter is used, which is embedded and installed on the door panel of the power distribution cabinet. The size of the face frame is 96mm × 96mm. In addition to measuring all electrical parameters, it also has the maximum demand, 2-31 order current, voltage harmonic components, Functions such as voltage crest factor, current K factor, telephone form factor, current and voltage unbalance, positive and negative zero sequence component analysis. The appearance of ACR120EL and ACR230ELH multi-function meters and their practical application in low-voltage distribution cabinet are shown in Figure 3.
Figure 3 The appearance of ACR120EL and ACR230ELH multi-function meters and their application in power distribution drawers
2 Networking of power meters Power meters can be used as internal management meters alone, replacing a large number of traditional analog meters, and can also be used as a front-end device for power monitoring and energy management systems to achieve remote data collection and control. The RS485 communication interface in line with industry standards makes networking easy and convenient, and is an ideal choice for SCADA system integration.
The shielded twisted pair is used for bus-type connection between the instruments. Figure 4 shows the wiring diagram of the ADL instrument communication cable. By networking the on-site power meters of the power distribution system and reaching the monitoring host via the communication network, the scattered meters are connected as an organic whole.
Figure 4 Schematic diagram of power meter communication cable wiring
3 System structure and realized functions The large-scale public building energy management system can use the field bus to realize the functions of electric energy collection and electric energy measurement in the form of optical fiber ring network, Ethernet or wireless network. The system uses computers, communication equipment, and on-site power metering devices as basic tools to provide a basic platform for real-time data collection, remote management, and control. The system mainly uses a hierarchical distributed computer network structure, sub-station control management layer, network communication layer and field device layer [2] (Figure 5).
Figure 5 Power management system
Power instruments are connected to each other with shielded twisted pairs, and form a background monitoring and management system with communication servers, switches, industrial-grade computers, etc., to realize the monitoring of the power distribution system and the management of electrical energy metering. The main functions realized by the system:
(1) Real-time collection and display of operating parameters, such as voltage, current, power, power factor, active energy, etc., provides a basis for measurement management during normal operation and analysis of failure causes when an accident occurs.
(2) Monitor the operating status of electrical equipment, such as the current opening and closing status of various types of switches such as high and low voltage incoming circuit breakers, whether they are operating normally, and automatically alarm if a fault is found.
(3) Record and count the electricity consumption of all equipment in the building, including power consumption, lighting and socket consumption, air conditioning consumption, special consumption, etc., and can generate various reports and analysis curves for users Use for inquiries.
(4) Event recording and fault alarm, the system has a detailed recording function for all user operations, switch displacements, parameter violations and other events actually required by users. It also has an alarm function for information such as switch displacements and parameter violations. .
4 Application Cases A library in Shanghai Pudong is a large public building with high energy consumption, with a total construction area of ​​60,885 square meters. The library transformer and distribution system uses medium-voltage microcomputer protection devices and multi-function power meters to protect circuits and collect electrical parameter data in real time All medium-voltage microcomputer protection devices and power meters are networked through the field bus. In the central control room, the power consumption of each loop in the field is monitored, and the database is stored. The daily electricity report, monthly report, annual report and electrical energy are automatically generated. Measurement statistical reports, etc., provide a reference for management personnel to analyze and make decisions.
The electric energy management system of this project adopts a three-layer network structure, and the station control management layer is a direct window for human-computer interaction, which is mainly composed of industrial control computers. The communication management layer is mainly composed of communication servers and switches, etc. It is a bridge for data information exchange. It is responsible for collecting and transmitting the data information returned by the field devices and transmitting various commands of the host computer to the field devices. The electric instruments on the field equipment layer are mainly ACR series multi-function meters and ADL series rail-type meters. ACR series multi-function meters are used for low-voltage incoming circuits and important feeder circuits. ADL series rail-type meters are used for ordinary feeder circuits, power boxes and lighting boxes Electricity meter to measure the electric energy of each circuit and each floor of the scene.
The power management system of the monitoring room completes the data collection of each power consumption circuit through the transmission channels provided by the field equipment and the communication system. The information is analyzed and processed, and it is provided for the duty personnel in various forms such as reports and graphics, so that the duty personnel can be convenient Grasp the operation of the system and the use of electrical energy, and find and correct the waste of electricity in a timely manner, thereby saving electricity. When needed, it can also provide fast remote control means to complete the change of equipment operating status and the handling of accidents. Figure 6 shows the library energy metering query table, which clearly shows the usage of electricity by sub-items. Figure 7 is a pie chart of the sub-item power consumption of the library lighting, air conditioning and sockets given by the system, which intuitively shows the percentage of sub-item power consumption.
Figure 6 The inquiry table of the electric energy sub-item measurement of the library
Figure 7 Pie chart of annual electricity consumption of the library
5 Conclusion With the development of society and the widespread application of electricity, electric energy management has become an inevitable choice for the intelligent construction of large public buildings. The electric meters introduced in this article can realize the itemization of electric energy and the measurement of time-sharing multiple rates. It displays the status of power consumption, and also has network communication function, which can form a power monitoring and power management system with computers. Realize the analysis and processing of the collected data, and generate various electrical energy reports, analysis curves, graphics, etc., which is convenient for remote meter reading, analysis and research of electrical energy. This series of power meters are reliable and stable, and will play an increasingly important role in building energy-saving measurement.
The article comes from: "Building Energy Conservation" 2010 Issue 6.
references
[1] Ren Zhicheng Zhou Zhong. Principles and Application Guide of Electric Power Measurement Digital Instruments [M]. Beijing. China Electric Power Press. 2007. 4
[2] Wang Bin, Du Yundong, et al. Design and application of large-scale public building energy consumption monitoring system based on Acrel-5000 [J]. Intelligent Building Electrical Technology. 2009.3 (5)
About the Author:
Yu Jing, female, undergraduate, engineer of Wuhan Ankerui Electric Co., Ltd., the main research direction is intelligent power monitoring and power management system
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