| With the development of power industry and the wide use of non-linear load, the pollution which they produced of power quality has seriously affect the grid safe operation, enterprise production and people’s daily life, which should be strictly controlled and supervised. Non-linear load not only inject harmonic to the grid, but also causes power quality problems such as voltage fluctuation and flicker, three phase unbalance, active impact, etc. Therefore, it is necessary to evaluate power quality of non-linear load before connecting the grid, which be allowed to connect to the grid after evaluation results qualified or controlled. At the same time, the consumers have improved the requirements of the power quality with the continuous development of the electricity market, so we need to have a scientific, accurate and standardized assessment of the power quality, to achieve a comprehensive power quality management. Power quality assessment principles mainly reflected in "who pollute, who is going to govern", and so on. Due to the huge economic losses caused by power quality issues, so the power quality has been more attention. In order to improve power quality and treat timely, the power quality assessment has drawn increasing attention.In this paper, a general description of the current study status of power quality and present development situation of power quality evaluation of non-linear load is given. At first, we have an in-depth understanding of the meaning of the power quality. Based on the general introduction the basic concept and related harm such as harmonic, voltage fluctuation and flicker, three phase unbalance, active impact, a system suitable for non-linear load power quality assessment is set up, and the relevant standard of the power quality assessment has been given. Then, the power quality of typical non-loads of electric arc furnace and intermediate frequency furnace is evaluated scientifically and specifically, and the factors affecting the assessment results are analyzed. At last, the power quality testing of arc furnace and the specific control measures of intermediate have been given. The work of the paper provides an important theoretical basis for the analysis of power quality problems on the supply grid, and it is also helpful to control and supervise power quality. |
