Research On Detection Algorithm And Network Monitoring System Of Power Quality

With the progress of technology and the improvement of socialist economic construction, China is gradually establishing electricity market mechanisms while a variety of non-linear devices and sensitive power electronic devices is introduced and thus the grid power quality requirements are higher and higher. The decline of power quality will cause varying degrees of impact on all aspects of the power system. At present the focus of power quality problem research has changed from the steady state to the transient state. The main premise of governance and improvement is the accurate positioning、recognition and classification of disturbance, so fast and high-precision detection algorithm is particularly important. With the acceleration of grid interconnection and the increasing of system size, network structure becomes more and more complex, so the real-time power quality monitoring and control is also the focus of research. To be able to monitor the operating status of power and ensure its stability, it is urgent to establish an economic and efficient monitoring system, which can through a visual interface to understand the power quality of the grid. Due to the development and close integration of modern computer networks and information networks, the WEB-based network monitoring system technology becomes to a mainstream in the future. Users can use the Internet and browser access to information for each area of power quality indicators anywhere. This paper focuses on the following:1. Introduces the research status of the analysis of power quality, measuring devices and monitoring systems; gives the concepts and classification of the power quality; discusses the various indicators and their corresponding detection methods of the power quality; Summarizes the advantages and disadvantages and scope of various detection algorithms.2. Algorithm Research. Modified generalized S-transform is proposed by introducing a frequency-dependent variable factor function. And the varying frequency of the analog signal is been simulated and analyzed. To use equivalent frequency curves illustrate its advantages compared with S-transform and generalized S-transform on the time-frequency resolution. Outline the problems and modified methods of empirical mode decomposition process, and then using constrained cubic spline interpolation fitting extreme points and a mirror method to extend signal to propose a modified Hilbert-Huang transform. Then these two methods and dynamic measurement, wavelet transform are applied to the detection of power quality disturbance signal. Through comparative analysis of amplitude, frequency and disturbance time and other parameters proved the availability and advantages of detection algorithm in this paper.3. Design of the system. This paper discusses the architecture and technical framework of WEB system used in development. Then according to the works of power quality monitoring devices, this paper designs power quality monitoring and management system based on browser/server mode and J2EE platform, including a hierarchical structure and mission module of the system. This paper also Introducted and selected a database and its access method and designed the database table structure.4. Implementation of the system. Network power quality monitoring and management system based on WEB technology for grid operating state real-time control is very important. It provides modules like site monitoring, data analysis, real-time display etc. The system puts Tomcat and Myeclipse as the server and development tools, using JDBC technology to access WEB data server to obtain site information and historical data etc., applying Highcharts to display historical data analysis, real-time data is obtained through Socket network programming, using Ajax technology to achieve the real-time display of more indexs.