Design And Analysis On Connecting Into The Power System For Non-linear Load

As quickly development of our national economy and the scale of industrial production expanding larger, non-linear load with large capacity incessantly springs up. the adverse impact on power quality with such load connecting into the power system must be paid sufficient attention. Now electric power users have more and more attention to power quality, so taking general study and giving resolution on non-linear load is quite necessary before its connecting into the net. Combining to the design of practical project, this paper takes detailed analysis and study at three aspects such as electrical primary scheme, electrical secondary scheme and power quality evaluation.The paper introduces characteristics of non-linear load and its disadvantage to power quality. PSASP program is used to calculate power flow and short-circuit current after non-linear load connecting into the net. The paper gives electrical primary scheme, and brings forward advices to user’s substation about main electrical connection, scale of transmission line, parameters of equipments, etc.. According to commendatory primary scheme, reconstructing schemes are gived about secondary schemes in public substation, including schemes of relaying protection, communication and automation. In the paper, the limits of power quality indexes are calculated, background of power quality in correlative public substation is tested, which is analyzed and compared with normative limits. ETAP program is used to simulate the three schemes of this paper and calculate harmonic voltage, harmonic current, voltage fluctuation and flicker, three-phase voltage unbalance. In the end, this paper generally summarizes power quality evaluation about schemes of non-linear load connecting into power system, and gives effective opinions and advices.