Yuan Kai 1 Lu Ming 2
1 Shanghai Capital City Architectural Design & Research Institute Co., Ltd., Shanghai Chongming 202150, China;
2 Shanghai Ankerui Electric Co., Ltd., Shanghai Jiading 201801;
Abstract : This paper introduces an intelligent power meter and transformer monitoring system in 10/0.4KV power distribution system. Real-time voltage and current, frequency, power factor, active energy and other electrical parameters and switching signals of the main circuit are real-time. Acquisition; through the network transmission to the background, in order to achieve real-time monitoring of power status and energy consumption monitoring of low-voltage distribution systems.
Keywords: variable distribution monitoring system; Acrel-3000; RS485 communication; energy consumption monitoring
0 Overview
Shanghai Huashan Hospital Ward Building is a medical building with a floor area of ​​approximately 20,000 square meters. According to the requirements of distribution system management and energy consumption monitoring, it is necessary to perform power monitoring on the high-voltage incoming line, low-voltage outgoing line, and distribution boxes in each floor in the building to ensure the safety and efficiency of electricity use.
Acrel-3000 low-voltage intelligent power distribution system utilizes the latest developments in modern electronic technology, computer technology, network technology and field bus technology to conduct distributed data acquisition and centralized monitoring and management of the power distribution system. The secondary equipment of the distribution system is networked. Through the computer and communication network, the decentralized field devices are connected into an organic whole, enabling remote monitoring and centralized management.
1 Composition of power distribution monitoring system
This system uses a hierarchical distributed computer network structure that is the field device layer, network communication layer and station control management layer shown in Figure 1.
Figure 1 System topology
The main equipments of field equipments are: multi-functional network power meters, switches, analog acquisition modules and intelligent circuit breakers. These devices are corresponding to the corresponding primary equipment installed in the electrical cabinet, these devices are used RS485 communication interface, through the scene MODBUS bus networking communications, data acquisition on the spot.
The main network communication layer is: a communication server. The main function of the communication server is to collect the scattered data at the site collection device, and transmit it to the station control layer at the same time, to complete the data exchange between the field layer and the station control layer.
Station control management: equipped with high-performance industrial computers, monitors, UPS power supplies, printers, alarm buzzer and other equipment. The monitoring system is installed on the computer to collect and display the operating status of the equipment in the field and displays it to the user in the form of human-computer interaction. At the same time, the user can send commands to the field device through the system software to realize the remote control function.
The above network instruments all adopt RS485 interface and MODBUS-RTU communication protocol. RS485 adopts shielded wire transmission. Generally, two wires are used for connection. The connection is simple and convenient. The communication interface is half-duplex communication, that is, both parties can receive and send data. Only data can be sent or received at the same time. The maximum data transmission rate is 10Mbps. The RS-485 interface is a combination of balanced drivers and differential receivers. It has enhanced noise immunity and allows up to 32 devices to be connected on the bus. The maximum transmission distance is 1.2 km.
2 The main functions of the monitoring system
The power monitoring computer completes the data collection of the power parameters of the loops through the transmission channels provided by the field devices and communication systems. The information is analyzed and processed, and is used by the on-duty personnel in various forms such as reports to enable the on-duty personnel to easily grasp the power supply system. The health of the equipment, including its operating conditions.
2.1 Operation Information and Protection Information Collection
The system collects the parameters sent from the intelligent measurement and control unit device, and all the information of the low-pressure main input, the bus couple, and the outgoing telemetry signal. Including each circuit's voltage, current, active power, reactive power, power factor, frequency, active energy, reactive energy and various alarm information.
2.2 Man-machine interface
The system provides simple, easy-to-use, and user-friendly interfaces. According to the distribution system, the equipment status of the distribution system and the corresponding real-time operating parameters can be displayed.
The system software provides full-featured graphics editing software. The user can customize the display mode of various graphics and devices in various states according to the actual situation and past habits.
Includes the following features:
The graphical screen edited by the full graphic mode has a variety of display characteristics, and the user can edit, locate, and view related information and content very intuitively and conveniently.
Provides a screen management tool that can associate relevant calls, quick call of important screens, screen file index selection, and automatic accident recall screen.
Provide a variety of numerical display means, the value can be displayed with a bar graph, curve display, and according to the user's needs and habits according to the status and status of the system to define flashing, discoloration and special symbols to distinguish between various data including telemetry The normal, the upper limit, the lower limit and so on.
Screen display: Chinese liquid crystal display, optional graphical color, flashing, animation and other means to fully represent the working condition diagram and operation screen, utility parameter table of the power distribution system, various types of operation ticket and report, accident and fault alarm display, measurement and control and protection unit Operation status display and other power running status; the screen shows response time 1s. See Figure 2.
Figure 2 Distribution System Diagram
2.3 Statistical Analysis, Reporting, Printing
Hourly, daily, monthly, and annual electricity consumption statistics; user-defined report formats and calculation methods; all report timing print, summon print, and event record printing; database real-time and historical records retained for more than 2 years; for all electrical equipment and The system operating parameters are summarized and statistics are generated, and various types of reports are generated according to user requirements, including: time-sharing, daily, monthly, quarterly and annual reports;
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Figure 3 Electrical Parameters Summary
Each device parameter and the most value statistical report; the whole system running statistical report, etc. For the event record, alarm and data report, can be set to timed and according to the need to call print.
Energy statistics report and printing, summary statistics of energy consumption, and generate various types of reports according to user requirements, including: time, date, month, quarter, and annual report; energy statistics report, active/not available for day, month, and year Statistics of electrical energy, and the output of the electrical energy report in the user's normal format, to achieve manual meter reading to automatic reports, can be set to time and according to the need to call the print, see Figure 4.
Figure 4 Energy Report
2.4 Historical Records and Trend Analysis
The system collects real-time data of each monitoring control and management device and stores it in an open database. The system can store long-term (years) history records. The system can recall and print the above history data at any time in standard and setup file formats.
According to historical data records, annual, monthly, and daily changes of various parameters and real-time data trend analysis can be carried out, and classification and comprehensive comparison and analysis can be performed to provide basis for optimizing business processes and optimizing the use of facilities and facilities, as shown in Figure 5.
Figure 5 Current trend graph
2.5 System Security
The system software sets up as many as hundreds of password partitions and password settings. It provides passwords for system administrators, engineers, value-changers, and general duty operators, and automatically records all operations with time-stamp events. Anti-accident measures, see Figure 6.
Figure 6 User Rights Management
2.6 Failure Analysis and Equipment Maintenance Management
The system can analyze the causes of faults and events based on event records and waveform records with time stamps. In addition, the status parameters and cumulative life parameters of the system's statistical switch and other devices can be used to provide advance notice of equipment maintenance; see Figure 7.
Figure 7 Event record
2.7 Protection Information Management
Manage protection settings and protection action information and provide related queries.
2.8 Other functions
Other day-to-day management, such as operation records and shift record management, equipment operation status, defects, maintenance records management, and rules and regulations. Management functions meet user requirements, application, convenience, and resource sharing. Various documents can be stored, retrieved, edited, displayed, and printed.
2.9 System Self-diagnosis Function
The system software can online diagnose the operating conditions of each software and hardware. When abnormalities and faults are found, the alarm information can be displayed and printed in a timely manner, and displayed in different colors on the operating condition map.
Due to the redundant configuration of the system's equipment, when the system has software and hardware failures, it can automatically switch to the standby system equipment.
3 Conclusion
With the rapid development of society, users are increasingly demanding the automation of supply and distribution and intelligence, and the realization of the unmanned duty of the power distribution room has become a direction for the development of power distribution automation in the future; ACREL-3000 type of variable distribution monitoring The system is a good solution to the high-quality operation of power supply and distribution. Operation shows that the system is reliable, safe and stable, and reduces the cost of equipment operation and improves the quality of distribution automation.
references:
Ren Chengcheng and Zhou Zhong eds. Principle and Application Guide for Power Electronic Measurement Digital Instrument China Electric Power Press 2007.4
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