Application of power monitoring software in intelligent power distribution system

At present, many buildings in China still generally use dry-type transformers with low-voltage cable distribution boxes to achieve decentralized power supply, which brings a lot of inconvenience to the operation and management of the entire system. With the increasing maturity of computer technology and network communication technology, the intelligentization and networking of distribution system measurement and control functions are the inevitable trend of development. Various problems in the operation of distribution systems can be fully solved by microcomputers.

The intelligent power distribution system is composed of switches equipped with intelligent components with communication functions, which are connected to the computer system network through digital communication to realize the automatic management of the operation of the switchgear in the decentralized low-voltage cable distribution box. The system can realize functions such as real-time data collection, digital communication, remote operation and program control, and equipment maintenance information management.

1 Project Overview

Shanghai Nuclear Engineering Research and Design Institute is a key research and design unit affiliated to China National Nuclear Corporation. The new building system of the institute is divided into the distribution room and the floor part. The high-voltage part of the distribution room uses ACR330ELH to collect harmonic data, and WHD72 to collect temperature and humidity data; the low-voltage incoming line side uses ACR320ELH to collect harmonics, power factor and other data, and ACR220EK network power meter collects and measures current. The switch status is connected to the DI (switch input) interface of the ACR220EK instrument through the auxiliary contact. The floor part uses ACR220E to collect power data. All electrical parameter data are transmitted to the host computer through the RS-485 bus through the communication interface of the instrument to realize telemetry, remote control and telesignaling functions.

2 System topology

The topology of the power monitoring system of Shanghai Nuclear Engineering Research Institute is shown in Figure 1. The system mostly adopts a distributed structure, divided by function or area, and modularized. The entire system is generally divided into three layers, namely the field layer, the middle layer, and the main control layer.

The main task of the field 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. Its main equipment is: ACR330ELH, ACR320ELH harmonic meters, WHD72D temperature and humidity meters, ACR220EK network power meters, which are installed in the cable distribution box on site. The above equipment completes their respective functions independently and does not rely on the main control computer to run. All instruments have RS-485 communication interfaces, and the detected electrical parameters and status signals are transmitted to the data processing unit of the middle layer in real time through the RS-485 bus on site.

The middle layer is located between the field layer and the main control layer, and is composed of photoelectric isolators and serial port servers. The field 485 bus is connected to the switch through the photoelectric isolator serial port server to complete the network communication connection and data exchange between the field layer equipment and the main control computer.

The main control layer is located in the central control room or duty room, and is equipped with high-performance, high-reliability industrial computers, UPS uninterruptible power supplies, printers, alarm devices, etc. Acrel-3000 power monitoring software is installed on the main control computer, and the real-time monitoring of the entire power distribution system is achieved through the software's human-machine interface and various management functions.

Figure 1 System topology diagram

The new floor monitoring center of Shanghai Nuclear Engineering Research Institute is located in the fire control room on the first floor, and the power distribution room is located in the underground garage on the second floor. The distance is no more than 1,200 meters, and communication can be carried out directly by laying RS-485 bus. Considering the geographical location of the site and the convenience and rationality of the wiring, an 8-way RS-485 network is used to cover all the monitoring points in the power distribution room; considering the convenience of wiring, a 3-way RS-485 network is used for the floor part, which is pulled to the fire control room through the shaft and ceiling. 3 Acrel-3000 Power Monitoring Configuration Software Solution

Acrel-3000 power monitoring configuration software is a special software for collecting and controlling on-site production data. Its biggest feature is that it can integrate the system in a flexible and diverse "configuration mode" rather than a programming mode. It provides a good user development interface and a simple engineering implementation method. As long as the various pre-set software modules are simply "configured", the various functions of the monitoring layer can be easily realized and completed. For example, in distributed network applications, all applications (such as trend curves, alarms, etc.) reference remote data in exactly the same way as local data. Through the "configuration" method, the system integration time of automation engineers can be shortened and the integration efficiency can be improved.

After the implementation of this system, functions such as power reports for various types of electrical equipment, real-time electrical parameter telemetry of each power circuit, power quality (including harmonics) analysis of important circuits, and load power consumption trends of important circuits have been realized. The charts are shown in Figures 2, 3, and 4 respectively.

Figure 2 Real-time electrical parameter remote meter reading

Figure 3 Important circuit harmonic parameters and bar graphs

Figure 4 Important circuit harmonic parameters and bar graphs

4 Conclusion

The configuration of network power meters in the power monitoring system has significant advantages such as simple implementation and low investment. It can conveniently and in real time monitor the operating status of the power distribution system, and uniformly manage the on-site power equipment, eliminating the tedious work of staff to record on-site. The system manages and analyzes the historical operating data and status of various power equipment, which is convenient for maintenance personnel to clarify the equipment status and formulate detailed equipment maintenance plans, reduce staff and improve efficiency. At the same time, according to the established power metering system, the overall energy consumption of the building can be understood and analyzed, a consumption reduction plan can be proposed, energy-saving and consumption reduction measures can be taken, and the power efficiency can be gradually improved.