Selective electric leakage protection system for low-voltage power grid of underground coal mine

Abstract

The invention discloses a selective electric leakage protection system for a low-voltage power grid of an underground coal mine, and relates to an electric leakage protection system for the underground coal mine. The system comprises a selective electric leakage protection addition DC source method electric leakage detection system, a zero-sequence power direction type electric leakage detection system, and a selective electric leakage protection system. The selective electric leakage protection addition DC source method electric leakage detection system is provided with an independent DC power supply between a three-phase power grid and the ground. The zero-sequence power direction type electric leakage detection system judges an electric leakage fault branch circuit through a zero-sequence voltage and a zero-sequence current. The selective electric leakage protection system selects a single-chip microcomputer in the C8051F040 series, and a CAN2.0B controller is integrated in a chip and has a mode of external crystal oscillation. A power supply circuit of the system achieves the selective switching-off of an electric leakage circuit through the detection of a zero-sequence current signal, and the whole power supply network is not cut off. The system is reliable in performance, is convenient and effective, is safe and stable, is high in cost performance, and achieves the optimization of power supply.

Description

technical field [0001] The invention relates to an underground coal mine leakage protection system, in particular to a selective leakage protection system for an underground low-voltage power grid in a coal mine. Background technique [0002] The underground environment of coal mines has a lot of dust, high humidity, and contains a variety of flammable and explosive gases. Leakage accounts for about 70% of the total faults in underground power supply systems. It not only causes personal electric shock, but also may cause gas and coal dust explosions, and may even detonate electrical detonators in advance. Installing leakage protection devices is extremely important for mine safety. [0003] At present, the leakage protection devices widely used in my country's underground power grid have a single principle, and there are many defects such as non-selective action, or easy misoperation, and some need enough zero-sequence current to make the protection operate. [0004] At pre...

AI Technical Summary

Problems solved by technology

At present, most of the underground leakage protection devices in our country have a single principle, and there are some defects. For example, the action is not selective when the additional DC source is detected; the action resistance value is unstable when the zero-sequence voltage is detected; The action resistance value is unstable during size detection, and it is easy to malfunction when there are few branches

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