Application Status and Thinking of AC Speed Regulation in Baosteel

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Application Status and Thinking of AC Speed Regulation in Baosteel [Copy link]

This article summarizes the application of AC speed regulation in the construction of Baosteel Phase I, II and III projects. Based on the analysis of the basic structure, performance, application effect, existing deficiencies and electromagnetic compatibility issues of various types of on-site applications, the article proposes the selection of AC speed regulation schemes and some key issues that need to be paid attention to in the post-process of Baosteel Phase III and the transformation of Phase I and II equipment.
1. Introduction

Baosteel is a world-renowned super-large steel conglomerate. From the start of construction and the laying of the first pile in 1978 to the official acceptance of Baosteel Phase III by the state in May 2001, it took more than 20 years for the construction of Phase I, Phase II and Phase III projects. Baosteel people have paid a lot of hard work for this, and only then has the huge scale of 11.4 million tons of steel produced annually been formed.

Baosteel has several major production lines, including raw material transportation, storage, processing, smelting, slab continuous casting, primary rolling, hot rolling, cold rolling, etc. It can be said that the production technology and equipment automation control level of these production lines are world-class.

The production equipment of steel enterprises can be divided into two categories according to process requirements: non-speed regulating and speed regulating. On the main production lines of Baosteel, all the equipment that has speed regulating requirements in the production process has realized automatic speed regulating control.

From the perspective of electrical transmission: speed regulation can be divided into two categories: AC speed regulation and DC speed regulation.

2. Application of AC motor variable frequency speed regulation technology in Baosteel

The application of AC motor variable frequency speed regulation technology in Baosteel has developed along with the construction of Baosteel's Phase I, Phase II and Phase III projects.

When designing the first phase of Baosteel, although the frequency conversion speed regulation technology of AC motors had been developed quite well abroad, the DC speed regulation was still used in the imported projects of the first phase of Baosteel due to the current situation in China. Only two sets of inverters were introduced for starting large motors: one was the 12MW (12kV, 1024A) AC-DC-AC inverter produced by Toshiba Corporation of Japan for starting the 48MW synchronous motor of the 1# blast furnace blower of the Ministry of Energy. The other was the VS-630 (850kVA, 1750V, maximum output frequency 30Hz) current type AC-DC-AC inverter produced by Yaskawa Corporation of Japan for starting the 1600kW asynchronous motor of the primary and secondary dust removal fans of the 1# blast furnace.

In the second phase of the project, the application scope of AC variable frequency speed regulation technology has been expanded, and the proportion of equipment using AC variable frequency speed regulation technology in equipment that needs speed regulation has increased significantly. The frequency converters used are mainly SPWM voltage type. Most of these frequency converters (except for the R3 and roller drive frequency converters of the 2050 hot rolling mill, which use analog device control systems and thyristors as power switch elements) use transistor power switch elements GTR that can be turned off, and digital or fully digital control technology is applied. For example, the VS-686TV series and VS-616H series used for dust removal in the first steelmaking continuous casting and the second blast furnace iron-making field, the MELTRAC-200k series and REQROL-400 series used in the second sintering plant, and the AC-AC frequency converter used in the 2050 hot rolling R3, and the AC-DC-AC frequency converter used for the rolling line roller drive. Generally speaking, DC speed regulation still occupies a dominant position in the second phase of the project.

In the third phase of the project, more than 99% of the speed control systems used AC motor variable frequency speed control technology. For example, the main rolling mill of the 1580 hot rolling mill uses the three-level dual PWM synchronous motor vector control variable frequency speed control system M-3000 with GTO as the switching element and high power factor rectification; the rolling line auxiliary machines and rollers use the three-level dual PWM asynchronous motor vector control variable frequency speed control system M-2000 and M-1200 with IGBT as the power switching element; the five-frame AC-AC variable frequency vector control system of the 1420 cold rolling mill uses thyristors as power switching elements; the auxiliary machines of the 1420 cold rolling mill, the main and auxiliary equipment of the second steelmaking continuous casting equipment, and the third sintering main machine use VS-676, VS-616H3 variable frequency speed control system; 1550 cold rolling mill five-frame three-level PWM variable frequency speed control system with high power factor rectification using IGBT as switching element; ACS600 series direct torque control (DTC) variable frequency speed control system and load commutation (LCI) AC-DC-AC synchronous motor variable frequency speed control system for high-speed wire mill rolling line; and the ladle trolley drive of the second steelmaking plant, the stacker-reclaimer of the raw material yard, the unloader of the raw material terminal, and the travel control system of some cranes all adopt AC variable frequency speed control technology. It can be said that the application of AC variable frequency speed control technology in Baosteel has reached a fairly wide range.