Abstract: The power distribution system of a factory was upgraded using the Acrel-3000 power management system, realizing remote monitoring and centralized management of each power distribution circuit. It can automatically calculate the energy consumption per unit output, providing a basis for scientific energy-saving management. This paper introduces the structure, functions, and software implementation of the power management system. The characteristics of the ADL rail-mounted energy meter and its communication cable wiring method are particularly described.
Keywords: Power management system, electricity meter, DIN rail mounting, RS485 communication
1. Introduction
In response to a series of policies and measures formulated by the State Council to promote energy conservation and emission reduction, all sectors across the country have actively taken measures to save energy and electricity, achieving positive progress. However, whether the implementation of power energy-saving schemes and the widespread adoption of energy-saving equipment have truly played a role in energy conservation must be scientifically judged through a reasonable assessment and management mechanism.
A company's factory has one phase I power distribution room and two phase II power distribution rooms, providing electricity for the entire factory's production, lighting, air conditioning, and other needs. The original power distribution system only had electricity meters installed on the main incoming circuit of the entire factory. Managers could only know the monthly energy consumption from the total electricity consumption figures provided by the power company. They were unclear about where the electricity was used, whether there was any waste, and whether energy-saving measures were effective. A reasonable energy consumption assessment mechanism is urgently needed to achieve scientific energy management.
To address the above issues and in accordance with customer requirements, the original power distribution system was upgraded. The upgraded Acrel-3000 power management system not only enables remote monitoring and centralized management of each power distribution circuit, but also allows for categorized power consumption statistics based on each monitoring device, multi-rate power consumption statistics, 8-hour shift energy consumption statistics, daily energy consumption statistics, and monthly energy consumption statistics. It automatically calculates the power consumption per unit of output, providing a basis for scientific energy-saving management.
2. Project Analysis
This power management system is a low-voltage power distribution renovation project that adds power meters with communication interfaces to the existing power distribution cabinets, transmitting power parameters to the monitoring center to achieve centralized remote monitoring and management.
To achieve statistical analysis of the electricity consumption of each machine and data collection for each outgoing circuit, an energy meter must be installed on each outgoing circuit. However, most energy meters on the market currently use traditional wall-mounted installation methods, which are bulky and inconvenient to install. The company's existing power distribution system consists of drawer cabinets, with ammeters and indicator lights already installed on the drawer panels. The installation space is extremely limited, making it impossible to add any traditional energy meters to the drawer panels. The components inside the drawers are already very tightly packed, making it impossible to install either traditional energy meters or digital power network meters.
What if we were to draw measurement lines from each circuit transformer, build new meter boxes, place them next to the distribution cabinet, and centrally install the electricity meters in the meter boxes? This method would result in a large number of cables from the meter boxes to the distribution cabinet. Given the large number of power distribution circuits in the company's factory, installation and wiring would be complicated, and future inspection and maintenance would be difficult. Adding so many cables and new meter boxes would also increase the user's economic costs. Therefore, this method is not advisable.
Taking into account various factors such as instrument installation, commissioning, and subsequent maintenance, the ADL series DIN rail mounting energy meter was ultimately selected. This series of meters can be easily installed on the DIN rail at the back of the distribution cabinet without requiring new drilling into the cabinet or running a large number of cables to a new meter box. Installation is convenient and saves significant costs on cables and meter boxes. Moreover, this one-to-one measurement method makes future system inspection and maintenance very clear and convenient.
The ADL series DIN rail-mounted energy meters are equipped with a standard RS485 communication interface and adopt the Modbus RTU international standard communication protocol. The meters are networked through the communication interface, ultimately enabling centralized monitoring and management at the monitoring center.
3ADL rail-mounted energy meter
The ADL series of DIN rail-mounted energy meters includes single-phase multi-tariff energy meters and three-phase multi-tariff energy meters. This series of energy meters is compact, aesthetically pleasing, and modular in structure, and can be installed on a 35mm standard DIN rail. Figure 1 shows the appearance and installation method of the ADL series meters.
Figure 1. Appearance and installation method of ADL series instruments
The ADL series DIN rail mounted energy meters support both primary and secondary connection methods. They can be used not only in low-voltage distribution cabinets but also in terminal distribution boxes. The maximum ammeter specification is 20(80)A.
The ADL series DIN rail mounted energy meters are not only flexible and convenient in appearance and wiring, but also have the following advantages in function and performance:
a. It measures active power in both directions, automatically identifies and indicates the direction of power flow, and has 4 tariff rates and total energy metering functions.
b. Time-sharing rate function: The daily time period can be set with 4 rates and 8 time periods, and the minimum time unit within the time period is 1 minute.
c. The monthly freeze and transfer function can calculate the total electricity consumption and hourly electricity consumption of the month before last, the month before last, and the current month, which can be used for monthly electricity bill settlement and monitoring of electricity consumption.
d. Real-time monitoring function, measuring and displaying voltage, current, frequency, power, and power factor.
e. Output Interface. An opto-isolated power pulse data output interface can be used for meter calibration and remote transmission in a DCS (Distributed Control System). The RS485 communication interface enables remote meter reading and load monitoring.
4 System Composition
The power management upgrade system adopts a hierarchical distributed computer network structure, namely the bay layer, communication layer and station control layer, as shown in Figure 2.
Figure 2 Schematic diagram of the power management system
The instruments are connected via shielded twisted-pair cables in a bus configuration, and access the monitoring host through a communication expansion card. Figure 3 shows a schematic diagram of the ADL instrument communication cable wiring. By networking the secondary equipment of the power distribution system and connecting it to the monitoring host via the communication network, the distributed field devices in the power distribution substations are connected into a unified whole.
Figure 3. Schematic diagram of ADL instrument communication cable wiring
The monitoring center is equipped with a monitoring computer, printer, UPS power supply and necessary auxiliary equipment. The Acrel-3000 power management software completes the remote acquisition and centralized processing of data from each power meter.
5. Software Implementation and System Functions
5.1 Software Implementation
The host computer software uses Acrel-3000 configuration software to configure devices, configure database variables, design interfaces, etc., and complete the functions of monitoring and power management in the host computer software.
5.2 System Functions
The entire system realizes the collection and statistics of electrical energy of all circuits in the Phase I and Phase II power distribution rooms, and functions such as remote automatic meter reading and power statistics, including:
a. Remote power parameter measurement, including real-time power, allocated power, total power, and power statistics by each monitoring device.
b. Monitoring operational status and providing alarms for communication anomalies.
c. User management: Different user permissions have different operation functions, and each level of permission has the function of password modification and permission error prevention.
d. Electricity reports: Enables querying all electricity reports by time, categorized into five types: minute, hour, shift, day, and month, including total, peak, off-peak, and valley electricity rates and electricity consumption.
e. Energy bar chart: Real-time energy bar chart display of any loop, including total, peak, flat, and valley energy.
f. Summary table: summarizes the power consumption of all monitored devices, allows querying by time period, and automatically calculates power consumption for any time period.
g. Unit energy consumption: Automatically calculates energy consumption per unit of output, and can print and export the results. The interface for calculating energy consumption per unit of output is shown in Figure 4.
h. Printing and exporting: All reports and interfaces can be printed or exported in EXCEL or WORD format.
Figure 4 Single-chip energy consumption report
6. Conclusion
The system has been debugged and accepted, and is now successfully put into operation. The system software screen refresh time is less than 1 second, the remote signaling processing accuracy is greater than 99.9%, and the entire system operates safely and stably, greatly facilitating user operation.
The application of ADL rail-mounted energy meters is of practical significance for accurate energy measurement, saving installation space, and reducing engineering costs. Compared with traditional wall-mounted energy meters, they are compact, simple in appearance, flexible in wiring, and easy to install, which facilitates the simplification and centralization of energy management system transformation.
The system calculates the energy consumption of each monitoring device separately according to customer requirements, as well as the energy consumption per unit output for shared equipment. It also generates reports in four types: minute, hour, day, and month. This convenient energy database reporting greatly reduces the manpower required for meter reading and provides managers with an intuitive basis for internal metering assessments, laying the foundation for further energy-saving management and the implementation of energy-saving measures.
References
Ren Zhicheng, Zhou Zhong. Principles and Application Guide of Digital Instruments for Power Measurement. Beijing: China Electric Power Press, 2007.
For more detailed information, please contact:
Contact person for Jiangsu Ankerui Electric Manufacturing Co., Ltd.: Xu Yuli, Tel: 13771584106
QQ: 1759867226
MSN: [email protected]
Telephone: 0510-86179968
Fax: 0510-86179975
Email: [email protected]
Homepage: http://www.jyacrel.cn/
Address: No. 5, Dongmeng Road, Nanzha Town, Jiangyin City, Jiangsu Province
