Design Of Power Quality Overlapped Disturbances Monitoring System

With the vigorous development of the national economy and science andtechnology innovation, application devices with nonlinear, impact, imbalance loadand riching harmonic influx into the power system, having improved people’squality of life and productivity, at the same time that bringing convenience to people,these devices also take out serious pollution and lead to a decline in power quality.Nowadays, because of the numerous using of digital devices which use computer andmicroprocessor as the core in industrial production, user put forward higherrequirements on the reliability of power supply. Therefore, power quality problemhas become a hot spot at the present. And the identification and monitoring of powerquality disturbances also received considerable attention in the power system.A set of high-quality power quality monitoring system is the basis of the powerquality control. However, at the present stage most of the power quality monitoringsystem can only monitor and identify a single power quality problem, in most cases,the situation of several disturbances superimposed is often occur in power qualityproblems that requres a new kind of monitoring system. Therefore, this paper focuseson the study of the superimposed power quality disturbances recognition method,and develops a set of monitoring system of the superimposed power quality problembased on virtual instrument technology. For algorithms: At first, making use ofwavelet thresholding method to de-noise power quality disturbances. The second,using phase shift method and Hilbert combined method to locate the disturbance. Atthe last, use the method of EEMD to decompose the multiple power qualitydisturbance signal into single power quality disturbance signal to recognize. For thehardware structure: A design of monitoring system using a small industrialmotherboard for core. For software design: designing of software system withLabVIEW platform, which comprises four threads. Respectively, the four threadscomplete the functions that are extraction of the original data, the calculation of basic amount, the perturbation positioning and the decomposition and recognition ofsuperimposed power quality.The system uses EEMD algorithm to realize the monitoring of superimposedpower quality disturbances and have higher real-time and monitoring accuracy. Itprovides good protection for the power quality control and has practical applicationprospect.