Research And Development Of Power Quality Real-time Monitoring System For High Voltage Switch Cabinet

As an important equipment of complete sets in the power system, the high voltage switch cabinet plays a critical role in such aspects of power distribution, power generation, transmission, distribution, utilization, and the running data to monitor. As an intermediate hubs connecting power supply and utilization, to conduct real-time monitoring of power quality in the high voltage switch cabinet. First, the operation level of power grid can be evaluated according to the monitoring of power quality indexes; Second, the key parameter data by electric power monitoring system the data from power quality monitoring can provide a basis for the causes and solutions of the issue in the power grid; Finally, it can timely master the operation status of electrical equipment through real-time monitoring, and detect early hidden trouble of equipment, so as to make preventive measures to reduce the loss.In view of the problems for the traditional power parameters monitoring system with single-chip microcomputer or DSP as the core, the data processing efficiency is not high, low measuring accuracy, less monitoring indicators, poor applicability, and complex maintenance, difficult to meet the modern power quality requirements such as real-time, multi-parameter monitoring requirements. This paper make full use of the ability for data processing, data analysis, data expression and the advantage of network function based on virtual instrument technology, build a set of real-time power quality monitoring system based on Lab VIEW, which application installed in high voltage switch cabinet. In this paper, the main work is as follows:(1) To analyze the key parameters algorithm of power quality measurement and use FFT algorithm with adding window, which realizes the precise measurement of the harmonic parameters and effectively eliminates the leakage and noise interference. The problems of transient power quality disturbance(voltage sag, voltage swell and voltage short-time interruption) were analyzed, and the rapid signals decompose and reconstruction of the Mallat algorithm, the modulus maxim method is used to test the transient disturbance on the basis.(2) To conduct hardware design of power quality monitoring system for the high voltage switch cabinet. The key for the design is the embedded data acquisition system, including sensor selection, signal conditioning circuit, A/D conversion module and the embedded system based on S3C2440 microprocessor, which completes data acquisition and transmission. And in view of the high voltage, high current and the strong magnetic field environment of the operation condition under the high voltage switch cabinet, the system hardware anti-interference measures are presented.(3) To complete the software design for this system function realization, the core content is the program design of software algorithm with the Lab VIEW software platform,which realizes the measurement of key indicators of power quality, and use wavelet transform to complete transient disturbance monitoring. The results are accurate and visually display to the user. To implement the remote power quality monitoring of client-server-browser mode, and the network architecture for remote power quality monitoring is constructed in view of the high voltage switch cabinet.(4) To realize the key power quality indexes measurements such as the voltage deviation, frequency deviation, three-phase unbalance, harmonic and flicker, including the effective value, power, power factor, energy and other basic parameters of measurement, and capture the transient disturbance. The system also has function of the limit alarm, data storage, historical trends, report printing, etc. To complete remote power quality monitor based on Web server technology, which realizes the network monitoring model. It completes database design, which realizes the online or historical view for the change of the power quality data.(5) Through the power quality monitoring platform based on the high voltage switch cabinet in the laboratory, the system measuring accuracy conducts the actual verification according to the measurement results compared with the Fluke 437 power quality analyzer. Experimental results show that the design of the real-time power quality monitoring system is good performance, high precision, friendly interface, which meets the project goal request, and it has a very good market application prospect.