Research On Electrical Characteristic And Power Quality Assessment System Of Typical Nonlinear Load

As one of the efficient and clean energy forms, electricity has an irreplaceable role in the development of national economy and the people daily life. But with the continuous development of social and economic, more and more non-linear loads connected to the electricity grid to power system brought serious influence the power quality. Power quality problem not only affects the safe and stable operation of the power grid, but it also affects the user’s safe and economic production. Insight into the nonlinear load influence on electric energy quality, realize the load of the power quality evaluation and control of power grid companies and power users is of great economic value and social significance.This article selects the electric arc furnace and electric railways as the main research object of non-linear loads. Electric arc furnace is the most common in the industrial type of nonlinear, impact load, has a great impact on power grid power quality. With the advent of China’s "high iron age", the influence of electric railway on the power grid is more serious. This paper analyzes the working principle of electric arc furnace and electric railways, and derived to calculate the electric arc furnace and electric system model of electric railway.Secondly, this paper analyzes the electric arc furnace and electric properties of electrified railway. The definition and calculation method of the main power quality standard was expounded. The measured waveform is used to verify the electric arc furnace and electric railway’s influence on the electricity. Nonlinear load will cause a high power factor, harmonics, voltage unbalance, voltage flicker and other issues. Nonlinear load influenced the power quality, and also will be affected by the bad power quality. According to the characteristics of the electric arc furnace and electric railways respective corresponding compensation strategies have been proposed.Finally, this paper established a nonlinear user access management process, and put forward the nonlinear load evaluation system. The main steps are to establish database, to collect user data and user PCC point of background information, to generate assessment based on three-level evaluation system. This method considers the influence power quality is different, and different users with different characteristics should adopt different evaluation scheme. It saves manpower and material resources and time cost.