Cascade STATCOM And Its Application In The Steel Industry

The arc furnace as a typical form of modern steelmaking equipment, owing to its remarkable economic benefits, widely existed in the metal smelting industry.Based on the electric arc furnace as the main research object, according to its working principle and electric characteristic, this paper studied it, and carried on the reactive power compensation, thus improving the electrical characteristics for surrounding system. The most of the world steel industry used static reactive power compensator(SVC) to solve reactive power compensation for electric arc furnace. But because of current changed quickly, the response speed of SVC cannot follow the current real-time changes, at the same time corresponding compensation device of fast chronic was directly related to the inhibition effect of voltage flicker and fluctuations. So the compensation effect of SVC was far below the requirements. In this paper, by compared the respective characteristics of SVC and STATCOM, decided to choose to replace the SVC with STATCOM, compensated for the iron and steel industry.The various advantages of STATCOM has been described in detail, and the working principle of its application in compensation of electric arc furnace has been introduced also.The electric arc furnace operating characteristics has been introduced, the causes of reactive power fluctuation and unbalanced system, then expounded the theory basis of instantaneous reactive power theory and the dynamic compensation principle.This article not only compensated reactive power component but also compensated the negative sequence of electric arc furnace, pointed out that the system in electric arc furnace under the condition of unbalanced, voltage asymmetry not only affected the reactive power compensation performance,but caused the device damage or out of operation.In order to solve this problem, it derived the running characteristic at imbalance system, Using symmetrical component method and the coordinate change on system voltage imbalance to separate positive and negative sequence component, And according to this, advanced the positive and negative sequence double loop control strategy based on feedback linearization, so as to solve the unbalanced system situation and reactive power compensation device of the negative sequence compensation problem, whose effectiveness was verified by simulation.