| The mine hoists are very important for coal production. They are key equipments. The technical performances of hoist electric control devices not only affect the efficiency and safety, also represent the development level of mine hoist. Now, in our country, the 90 percent of mine hoists adopt conventional AC asynchronous motor drive below 1000KW per single one. They regulate speed using serial rotors and chip resistors, construct logic control device by relays and contactors. The majority employs electromotor-generator sets, and the minority adopts thyristor rectifier drivers. The obvious shortcomings of conventional AC drive systems are as follows: poor speed adjusting performance, a great deal energy waste by the resistors during speed adjusting process, old setting way, bad control precision, faulty safety protection and monitoring parts, poor safe reliability, a lot of maintenance workload and uneconomical run.The F-D control system is used by electric control of main well hoist in Wangfenggang mine, Huainan mining company, which is built by former Russia in 1950s. The control system employs DC generators and delays. They aged after more fifty years run, and they cann't satisfy current production requirements. Since 1990s, it has become possible to build a set of whole digital control system for the computer and digital technology development. The whole digital DC speed adjusting systems have generally been applied in well hoist SCR-D system in our country. They correct basically F-D control system shortcomings and have great advantages contrast to other control systems. This paper is based on alteration project of the main well hoist in this mine.The paper proposes demand analyses for mine hoist drive and electric control system alteration, adopts the mode of "host computer monitoring + lower multi-PLC controlling + microprocessor multi-digital adjusting + motor driving". We alter original DC hoist control system, main well load & unload system and hoisting signals system for automation. The whole system uses PLC control instead of manual operation, realizes many kinds of safe protections and automatic run function for hoist, hoists main well hoist automatically. The main design contents are followings. In light of the complicate industrial situation of DC hoist, this paper proposes fuzzy parameters self-adaptive PID control. This method solves nonlinear vibrative problem of high-power system, improves speed control precision and run stability for hoist. The paper builds multi-PLC redundant control system, designs double PLC travel control for hoist and two-line safe circuit loop of PLC and delay, proposes PLC control network of hoist automation etc. The paper uses whole digital DC drive system to alter original "F+D" system, presents FLC-based coordinating control algorithm for hoist drive and brake system, solves historical difficult problems. The problems are hoist's load side suddenly decreases during operating the device because of brake too fast running, or hoist withstands current shock because of brake too slowly loosing. We program hoist monitoring software by VB6.0 language, realize network publishing functions for hoist running parameters and situations by Winsock and ActiveX technology, implement system long-distance monitoring and network managing.The whole control system has run after self-alteration. The whole system runs steadily and safely with efficient electrical effects. It has great promotion functions for industrial automatic equipments level in mine hoisting system, and achieves distinct economic effects and improves mine production efficiency. |
