The Design And Development Of Harmonics And Interharmonics' Detection System In Power System

The power quality is AC quality which supply to users through common electricity grid, including the voltage quality, current quality, supply quality and utilazation quality. The electronic and electrical elements widely used in power system can bring out the interharmonics and harmonics. They not only made consumers didn't work normally, but also were hard to estimate correctly. So it was difficult to control the interharmonics. The interharmonics and harmonics detection and analysis are the premise of control of inharmonics and harmonics whose efficiency can be lifted because of the correct detection.In this paper, a harmonics and inharmonics detection system, which was based on two levels computers structure, was designed. The data were collected using ARM system and transmitted to PC using the serial communication. In the upper monitor, Gershgorin Disks(G-Disks) was used to estimate the number of the harmonics and inharmonics. ESPRIT algorithm was used to estimate the frequency. Optimized harmonics and inharmonics estimation using Tagaki-Sugano Fuzzy Model(T-S Model) was designed. The parameters of estimation were gained by T-S Model. The optimized estimation included two steps. In the first step, abundant data were sampled to calculate offline and the parameters of T-S Model, which met the need of error and variance, were obtained after learing.In the second step, optimized parameters were used in online calculation. New sample interval and sample number were transmitted to ARM system through the serial communication in order to adjust the set of sample in ARM system. New G-Disks parameter was also used in the G-Disks. So the number and the real-time frequency of harmonics and inharmonics could be estimated correctly. At last, the real-time amplitude also could be estimated using the sample data and estimated frequency. These data could be saved by MySQL database. A web user interface system was designed including some web pages. After user and database login, user can view the real-time data and search the history data for analysis. This interface system was not required to install on the computer of remote monitor center and only need to connect the internet and view data using IE browse.As a result, the optimized interharmonics estimation using T-S model can detect correctly the frequency and amplitude in a short time in the simulation and experiment. The harmonics and inharmonics estimation system has use value.