Power Quality Monitoring For Shanwei Power Grid And Its Analysis

Recently, with the development of economic and the construction of distribution network of Shanwei, more and more different kinds of power load are coming out, in particular, nonlinear and impulsive load. On the other hand, the automatic and intelligent devices, as well as the computer-based or micro-processing controllers require higher power quality in power system. Therefore, the monitoring and analysis of power quality for the regional network becomes very important.Power quality consists of voltage deviation voltage fluctuations and flicker frequencydeviation harmonics phase unbalance and transient index, through the corresponding national standard definitions and limits to evaluate the regional power quality. The power quality disturbance sources are mainly transformers, generators, electric arc furnaces and fluorescent lamps and other traditional power generation and electrical devices, and a variety of new power electronic devices, which increase the power loss, make protection malfunction, and communication interference, eye fatigue, even affect the normal operation of equipment to interrupt the production line. This directly influences the economical benefits of society and people's common interests.According to the actual situation of Shanwei regional power grid, two on-line power quality monitoring system(PQMS) are introduced, and are monitoring four points of four transformers in the 220kV Haifeng station and Guizhu station. Through in-depth study and analysis of collected data, we found that the harmonic distortion(THD) of the 95% probability value exceeded the national standard requirements at the 10kV terminal in Haifeng station; in addition, voltage flickers at the 110kV terminal and 10kV terminal of the four transformers in the two stations is very serious and exceeds the requirement; the other five indicators meet the national standard requirements. Combined with the local power grid structure and loads, we speculate that harmonic may be caused by nonlinear loads; voltage flicker by the high-power, impulse load.According to the problem of power supply, we take strategies and solutions from the two aspects of voltage fluctuation and flicker and harmonic control.