Abstract: This paper introduces the application of the Acrel-3000 power monitoring system based on the ACR series programmable smart electricity meter in the Haimen Administrative Center, realizing intelligent power monitoring with distributed data acquisition and centralized control management.
Keywords: government agencies; smart meters; power monitoring software
0 Introduction
Haimen is located in the famous Yangtze River Delta. It was established as a county in 958 AD (the 5th year of Xiande in the Later Zhou Dynasty). It was named after being the gateway to the sea from the Yangtze River and is known as the "Hometown of Cotton and Grain, and a Happy Land by the River".
The Haimen Administrative Center Power Monitoring and Energy Management Project, initiated in July 2009, aimed to achieve centralized management and monitoring of the power systems in Buildings A, B, H, and the main building of the administrative center, realizing a remote intelligent power distribution system. This project implemented intelligent management of the power systems within the four buildings of the Haimen Administrative Center. The design consisted of four distribution rooms in the four buildings, connected to a power distribution center on the basement floor of the main building via fiber optic cables and photoelectric converters. Communication cabinets were placed in the four distribution rooms, and instrument data was transmitted to the power distribution center via a MOXA serial server and photoelectric converters through a 485 line.
1 System Structure
Acrel-3000 power monitoring software is a dedicated software for collecting and controlling on-site production data. Its most significant feature is its ability to integrate systems through flexible configuration rather than programming. It provides a user-friendly interface and simple engineering implementation methods. By simply configuring its pre-configured software modules, various monitoring functions can be easily implemented and completed. For example, in distributed network applications, all applications (such as trend curves and alarms) use the same method to reference remote data as they do to reference local data. This configuration-based approach significantly reduces system integration time for automation engineers and improves integration efficiency. The topology of the Haimen Administrative Center substation power distribution system is shown in Figure 1.
Figure 1. Topology diagram of power distribution system
The system adopts a distributed architecture, divided by function or region, and features a modular design. The entire system consists of three layers: the station control management layer, the network communication layer, and the field equipment layer.
1.1 Field Equipment Layer The main task of the field equipment layer is to collect and measure the operating parameters of various power distribution systems on site, and transmit the collected and measured data to the monitoring system via the network communication layer. Specifically, the main equipment in the main building's substation consists of 96 ACR220EL/KC and ACR330EL/KC programmable smart meters; the main equipment in Building A's substation consists of 63 ACR220EL/KC programmable smart meters; the main equipment in Building B's substation consists of 59 ACR220EL/KC programmable smart meters; and the main equipment in Building H's substation consists of 105 ACR220EL/KC programmable smart meters. All of these devices operate independently, without relying on the main control computer. They are equipped with RS-485 communication interfaces and transmit the detected electrical parameters and status signals in real time to the intermediate layer's data processing unit—the serial port server—via the field's RS-485 bus.
The ACR series programmable smart electrical meters utilize AC sampling technology to measure parameters such as current, voltage, power, power factor, and energy in the power grid. The multiplier can be set via a membrane switch on the panel. They feature an RS-485 communication interface using the Modbus protocol; can also convert electrical signals into standard DC analog signals for output; or include switch input/output and relay alarm output functions.
1.2 Network Communication Layer The network communication layer is located between the field layer and the main control layer, and uses a high-performance, embedded communication server. The communication server is responsible for uploading data collected by field layer instruments to the main control layer via network communication connection and data exchange, acting as a bridge between the main control layer and the field layer.
1.3 The main control layer of the station control management system is located in the power distribution room on the first basement floor of the main building. It is equipped with high-performance, high-reliability industrial-grade computers, UPS uninterruptible power supplies, printers, etc. Acrel-3000 power monitoring software is installed on the main control computer, which enables real-time monitoring and report management of the entire administrative center through the software's human-machine interface and various management functions.
The duty room of the Haimen Administrative Center is located in the power distribution room on the basement floor of the main building, and is equipped with an industrial network switch. The power distribution room in Building A uses 8 buses and an 8-port serial server, which is connected to the switch in the duty room of the main building via fiber optic cable. The power distribution room in Building B uses 6 buses and an 8-port serial server, which is connected to the switch in the duty room of the main building via fiber optic cable. The power distribution room in Building H uses 5 buses and an 8-port serial server, which is connected to the switch in the duty room of the main building via fiber optic cable. The data is then transmitted to the industrial control computer through the switch.
2. Main functions of power monitoring system
The system is designed based on the customer's actual needs and implements the following main functions: primary wiring diagram display; remote measurement of electrical parameters and alarm for exceeding electrical parameter limits; event logging; monitoring of abnormal system operation; fault alarm and operation log; report query and printing; real-time and historical curves of system load; and user access control.
2.1 Data Acquisition and Processing Data acquisition is the foundation of power distribution monitoring. It is primarily accomplished by underlying multi-functional network meters, enabling real-time local display of remote data. The signals to be acquired include: three-phase voltage U, three-phase current I, frequency Hz, power P, power factor COSφ, electricity consumption Ep, and the operating status of remote equipment.
Data processing mainly involves displaying the collected electrical parameters to users in real time and accurately, in order to achieve the automation and intelligence requirements of power distribution monitoring. At the same time, the collected data is stored in a database for users to query.
2.2 The human-computer interaction system provides a simple, easy-to-use, and user-friendly interface. It adopts a fully Chinese interface, displays the primary electrical wiring diagram of the low-voltage power distribution system using CAD graphics, shows the status of power distribution system equipment and corresponding real-time operating parameters, dynamically refreshes the screen in real time, and displays analog quantities, etc.
2.3 Fault Alarm and Accident Recall When an operational fault occurs in the power distribution system, an audible and visual alarm will be issued in a timely manner to prompt the user to respond to the faulty circuit. At the same time, the time of the event will be automatically recorded so that the user can query and recall the cause of the fault.
2.4 Database Establishment and Query: This mainly involves the timed collection of telemetry and teleindication data, the establishment of a database, and the periodic generation of reports for users to query and print.
2.5 The system periodically collects current load parameters of incoming lines and important circuits, and automatically generates operating load trend curves, making it convenient for users to understand the operating load status of the equipment in a timely manner.
2.6 The electricity cost management system automatically performs daily, monthly, and yearly electricity statistics and generates daily, monthly, and yearly reports.
3 Case Analysis
The low-voltage power distribution system of Haimen Administrative Center mainly consists of 10 10/0.4 kV distribution transformers. This system is primarily responsible for real-time dynamic monitoring of the low-voltage incoming lines and corresponding outgoing circuits.
The incoming line circuit uses ACR330EL/KC, which can measure various electrical parameters such as three-phase voltage, three-phase current, active power, reactive power, power factor, frequency, active energy, and reactive energy. It also has 4 opto-isolated switch input contacts and 2 relay control output contacts, and an RS485 communication interface.
The outgoing circuit uses ACR220EL/KC, which can measure three-phase current, has 4 opto-isolated switch input contacts and 2 relay control output contacts, and has an RS485 communication interface.
The low-voltage power distribution system mainly monitors the electrical parameters of the operating equipment, including: incoming three-phase current, power, energy, frequency and other electrical parameters, as well as the three-phase current of the outgoing circuit, as shown in Figure 2.
Figure 2. Low-voltage power distribution system diagram of Building B
The system communication status diagram allows you to view the communication operation status of each device in the system in real time, as shown in Figure 3.
Figure 3 Communication Status Diagram of Power Monitoring System
The remote meter reading function enables real-time remote meter reading of all major circuits, as shown in Figure 4.
Figure 4 Remote meter reading
The event logging function allows for real-time viewing of event logs and alarms, as shown in Figure 5.
Figure 5 Event Log
4. Equipment and Investment
The total cost of the system hardware, including data acquisition devices, power supply, workstation host, printing equipment, system software, and low-voltage installation, based on the actual site conditions, is approximately 190,000 yuan. Data from all aspects of power distribution can be centrally displayed on the monitoring host, facilitating timely detection of power distribution faults by management personnel. Monthly electricity consumption data can be compiled and uploaded to the Building Automation System (BAS) for overall dispatching. While this adds an initial investment compared to traditional meter reading and statistics by electricians, it significantly improves the level of intelligence and saves on human capital investment. It eliminates the tedious on-site meter reading by staff, offering advantages such as low investment, simplicity, practicality, and ease of intelligent management.
5. Conclusion
The Acrel-3000 power monitoring system boasts advantages such as versatility, high reliability, and flexible configuration, and has been successfully applied in the Haimen Administrative Center project. With the popularization of computer information technology, the requirements for intelligent low-voltage power distribution are increasing. Power distribution monitoring and management have made unmanned operation of power distribution rooms a reality. The system manages and analyzes historical operating data and status of various electrical equipment, facilitating maintenance personnel to understand equipment conditions, develop detailed maintenance plans, reduce manpower input, improve work efficiency, and thus lower the overall system operating costs.
References:
[1] Principles and Application Guide of Digital Instruments for Power Measurement, Ren Zhicheng and Zhou Zhong, China Electric Power Press
About the author:
Ni Zhongming (1982-), male, undergraduate, graduated from the School of Automation, Qingdao University of Science and Technology, and works in power distribution monitoring systems.
For more detailed information, please contact:
Contact person for Jiangsu Ankerui Electric Manufacturing Co., Ltd.: Xu Yuli, Tel: 13771584106
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