Mining winch is an equipment that completes small mine hoisting or auxiliary hoisting and transportation tasks with the help of wire rope traction.
Using VFD for speed regulation, it is convenient to realize multi-stage speed regulation of mining winches, and improve system stability and safety. It reduces operation failures and downtime, saves manpower and material resources, improves coal transportation capacity, and also has considerable indirect economic benefits.
When selecting the frequency inverter capacity, the difference in the performance of the mining motor and the fluctuation of the mechanical load should be considered. Xichi XFC500 universal variable frequency drive was selected in this project transformation.
XFC500 series VFD adopts open-loop current vector control, high reliability and high cost performance. It is suitable for various automatic production equipment such as fans and pumps.
Specific parameters and model selection: XFC500 low voltage AC drive
Reasonable application of frequency conversion technology to coal mine hoisting equipment can effectively overcome various defects of traditional hoist speed control technology. The whole hoisting system can achieve safe and stable operation, and greatly reduce the loss in the operation of the hoist, and improve the economic benefits of coal enterprises.
The speed control system adopts variable speed drive, with superior performance, and the vector control technology is suitable for the working environment of the hoist. Just by giving the control command to the VFD in the control unit, the hoist can run according to the set speed curve to meet the requirements of stable operation in the hoisting stage.
The frequency conversion speed control device itself has protections such as overvoltage, undervoltage, overcurrent, overload, phase loss, and overtemperature. At the same time, with the monitoring and corresponding processing of various signal sensors from the scene, the winch can realize important protection functions such as overwinding, overspeed, deceleration, speed limit, etc., and meet the requirements of safety regulations.
The effect that can be achieved after using the ac frequency inverter for speed regulation:
After the automatic frequency conversion speed regulation technology was introduced into the mine winch electrical control system, through debugging and trial operation, the current operation effect can meet the requirements of the hoisting process, and the effect is good. Specifically in:
✔ The automation degree of the lifting system has been significantly improved, the operation is simple, and the labor intensity of the employees is reduced;
✔ Through stepless frequency conversion speed regulation, fast, stable and high-precision speed regulation can be achieved, and the impact current generated by the hoist in the process of starting and accelerating is small, which is conducive to improving the performance and service life of the equipment;
✔ The VFD used is of reliable quality, and can be programmed according to needs. The online fault diagnosis system can conduct fault investigation in time, which is beneficial to reduce the fault processing time;
✔ The frequency conversion speed regulation can reduce the generation of harmonics, improve the input power factor, and the effect of energy saving and consumption reduction is obvious. According to the energy saving of 20%, the 1000kW electric motor can save about 600,000 yuan/year in electricity costs.
Requirements of mine hoist for electrical control system
1. The acceleration and deceleration are in line with the relevant national production safety regulations. When lifting people, the acceleration a≤0.75m/s2, when lifting materials, the acceleration a≤1.2m/s2, and the dynamic torque allowed by the reducer of the hoist must not be exceeded.
2. Good speed regulation performance. It is required to have stable speed, convenient speed regulation, and wide speed regulation range, which can meet the requirements of stable operation in various operation modes and promotion stages (such as acceleration, deceleration, constant speed, crawling, etc.).
3. Good starting performance. It must be able to start under heavy load and have a high overload capacity.
4. The characteristic curve should be hard. To ensure that when the load changes, the lifting speed is basically not affected. Prevent the speed from changing too much when the load is different, which will affect the normal operation of the system.
5. Easy to change work style. It is necessary to be able to easily switch working modes such as automatic, semi-automatic, manual, rope inspection, etc., with convenient operation and flexible control, so as not to affect normal production due to the switching of working modes.
6. Using new technology and energy-saving equipment, it is easy to realize automatic control and improve the working efficiency of the whole system. There are necessary chain and safety protection links to ensure the safe operation of the system. Minimize energy savings and lower operating costs.
Mine hoist speed control system
There are the following problems in the traditional mine hoist speed control system:
1. In this control method, due to the frequent actions of the AC contactor during the speed regulation process, the equipment runs for a long time, and the main contact of the AC contactor is easily oxidized, causing equipment failure.
2. The frequent starting, speed regulation and braking of the hoist will generate considerable power consumption on the series resistance of the external circuit of the rotor, resulting in energy waste, and the speed regulation control circuit of the rotor series resistance is complicated.
3. The speed control performance of the hoist in the deceleration and crawling stages is poor, especially when the load changes, it is difficult to achieve constant deceleration control, which often causes over-discharge and over-roll accidents.
4. This kind of rotor string resistance speed regulation belongs to step-by-step speed regulation, the operation is not stable, and it is easy to cause electrical and mechanical shocks.
5. The motor relies on the rotor resistance to obtain low speed, its running characteristics are soft, and the static difference rate is large.
6. The current shock is large during the starting process and the speed adjustment and shifting process, the vibration is large in medium and high speed operation, and the safety is poor.
The continuous development of modern technology integrates frequency conversion speed regulation technology and PLC technology into the electrical control system of the hoist. It can simplify the structure of its electrical control system, save a lot of AC contactors, time relays, intermediate relays and overcurrent relays, thereby greatly improving the reliability, controllability and safety of the hoist.
When the hoist is working in the power generation state, the electric energy can be fed back to the power grid. It has good speed regulation characteristics, the transition process is stable, the speed is continuously adjustable, the mechanical impact is small, and the electric energy is saved.