Research On Power Quality Detection Algorithm And Monitoring System

In recent years,due to the widespread use of a large number of computer-based precision instruments and electrical equipment capable of generating non-linear loads in national production,the power quality problems arisen have attracted the attention of the power sector and users.The primary method for improving and managing power quality problems is to establish a related monitoring system and use appropriate algorithms to analyze and judge the collected data.However,with the expansion of the power grid and the development of network technology,the requirements for related detection algorithms and monitoring systems are also increasing.In this context,two algorithms based on instantaneous symmetrical component method for disturbance detection and linear constrained minimum mean square harmonic detection are proposed.The data collected by IEC60870-5-104 protocol is analyzed and monitored on the established website and displayed on the system.The specific research contents are as follows:(1)Firstly,the background and significance of the research on power quality is introduced.Several understandings of the concept of power quality and some measurement indicators specified by the national standard are explained in detail.Several common detection algorithms are listed.Finally,the power quality detection algorithm and the status of research at home and abroad in monitoring systems is deeply understood.(2)The application of instantaneous symmetrical component method in power quality detection and analysis is studied.First,a set of three-phase voltage signals is assumed and one phase is determined as the disturbance phase,and then the phase component of each phase and the peaks of the positive and negative sequence components are calculated by the symmetrical component method of the time domain.The algorithm is applied to six common power quality disturbances for analysis.The negative sequence component of the disturbance phase can be used to determine the start and end time of the disturbance,also,the disturbance is classified according to the peak waveform of the positive and negative sequence components.(3)The least mean square algorithm has been widely used in the field of harmonic detection because of its low computational complexity and good stability.However,in order to avoid the weight offset and further improve the convergence speed,a linear constrained based least mean square algorithm is proposed.Harmonic detection technique,based on the least mean square algorithm,the algorithm adds a linear constraint to the weight variable and applies it to the evaluation of the amplitude and phase angle parameters of harmonic and irregular wave signals in different Gaussian white noise environments.The state signal,dynamic signal and actual signal model are tested.The harmonic detection capability of the algorithm under different environments is tested,and the convergence speed and anti-interference ability of the least mean square algorithm are compared.(4)The general architecture of the IEC60870-5-104 protocol,three packet formats of the protocol and the transmission control mechanism of the message are described.The data acquisition application based on IEC60870-5-104 protocol was written in C# language,and the data reception and storage work was realized through the interconnection debugging with the Cape Lab protocol test software.(5)The overall structure and function of the monitoring system are designed.The monitoring devices,B/S mode,Baidu map API and data communication technology used in the development process are briefly introduced.Finally,the power quality monitoring system based on WEB and Visual Studio 2010 software platform is built by C# language,and each module is introduced in detail.