Electric Power System Analysis and Design of an Expanding Steel Cogeneration Plant

This paper presents the electric power system analysis and design of an expanding steel cogeneration plant. The site and capacity of shunt capacitor banks as well as the tap position of transformers are determined according to the power flow analysis. Also, to comply with the restriction of circuit breaker capacity, the high-impedance transformers are designed. In addition, the voltage fluctuation resulted from the dramatic reactive power variation of hot strip rolling mill can be greatly reduced if proper static var compensator is installed. The significant voltage sag due to the starting of induction motor can be effectively improved by applying wye–delta transformer starter. Furthermore, the total voltage harmonic distortion and the total current demand distortion are both acceptable if the proper filters are installed. It is also found that the cogeneration system can keep stable operation in autonomous mode by applying the governor control action and the load-shedding scheme after tie line tripping. It is concluded that the power system analyses are important for the steel plant with cogeneration unit to identify hidden problems and remedy strategy to ensure the system power quality and operation performance.

I. Introduction

This Paper presents the power system design and analysis of an expanding steel plant. The existing plant makes steel by applying dc arc furnace and has an H-beam welding line. To increase the amount and diversity of products, the plant is planning to build many new mills like blast furnaces, basic oxide furnaces, and hot strip rolling mill (HSRM). After that, it will become an integrated steelmaking plant for converting iron into finished products. It is very important to provide power supply with high quality and high reliability to these continuous operation equipment. In addition, to make use of the waste gases which are the by-product of the iron making and to enhance the reliability of power system, many cogeneration units are considered to be installed in the steel plant. These new equipment and cogeneration units will make a significant impact on the planning and operation of the steel plant. It is therefore necessary to perform the various power system analyses for providing better system planning and operating strategy to enhance power quality and reliability.