Anti-low voltage ride-through solution device and working method for powder feeder frequency converter in thermal power plant

Abstract

The invention relates to a low-voltage ride through resistant solution device and method for a frequency converter of a pulverized coal feeder of a thermal power plant. The method comprises the following steps that a control device receives a rotational speed given signal, emitted from a DCS system of a power plant, of the pulverized coal feeder; the control device carries out closed-loop regulation control on an actual rotational speed of the pulverized coal feeder; a control execution mechanism drives a ball screw through a speed reduction device to move, and the ball screw simultaneously drives a permanent-magnet rotor to go forwards or backwards; and after the permanent-magnet rotor is inserted into an insertion hole, an induced magnetic field is generated between the permanent-magnet rotor and a conductor rotor and converted into torque mechanical energy, a transmission shaft is driven to rotate by a torque, and the rotational speed of a load is adjusted according to the depth of the permanent-magnet rotor inserted into the insertion hole. According to the method, the torque is generated by a mutual effect of the induced magnetic field, the size of the transfer torque is controlled by adjusting a superimposed area between the permanent-magnet and a conductor, so that the speed of the load is adjusted. Since power cannot be used by a main loop of the device, the problem of low-voltage ride through of the pulverized coal feeder of the thermal power plant can be effectively solved.

Description

technical field [0001] The invention relates to a permanent magnet speed regulation and energy-saving application device and control method for a powder feeder / coal feeder in a thermal power plant, in particular to a closed-loop control method based on rotational speed, which solves the problem of low-voltage ride-through of a powder feeder system in a thermal power plant. Background technique [0002] The powder feeder (coal feeder) of thermal power plants is an important auxiliary equipment, and most of them are operated by frequency conversion speed regulation at present. If the thermal power plant causes a short-term voltage drop in the power grid and power plant due to lightning strikes, short-circuiting of electrical equipment, and grounding, resulting in low voltage of the power supply of the powder feeder (coal feeder) inverter and low voltage of the inverter control power supply, these inverters The low-voltage blocking protection will operate, and the pulverizer (c...

AI Technical Summary

Problems solved by technology

However, most inverters have poor anti-low voltage ride-through ability, or even do not have this ability at all.

For the power grid, the voltage will drop instantaneously when the power grid fails, and active power support is urgently needed to maintain the system frequency. However, if the power plant is disconnected at this time, the frequency of the power grid will deteriorate further, and the consequences are very dangerous.

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