Residual current protection method and system

Abstract

The present invention relates to a residual current protection method and system. The method comprises: collecting the leakage current signals in a power supply grid; performing pretreatment of the collected leakage current signals; separating organism electric shock current signals from the leakage current signals after pretreatment; and determining whether the separated organism electric shock current signals are larger than a current presetting value or not, and if the separated organism electric shock current signals are larger than a current presetting value, executing the residual current protection tripping action. The residual current protection method and system employ the organism electric shock current signals separated from the leakage current signals to perform determination so as to avoid the problem of wrong tripping caused by large leakage current and improve the reliability of the residual current protection. Besides, the residual current protection method and system employ a current presetting value to determine whether there is organism electric shock or not so as to improve the accuracy of the determination.

Description

Technical field [0001] The invention relates to the technical field of residual current protection, in particular to a residual current protection method and a residual current protection system. Background technique [0002] Residual current protection technology, as an important low-voltage power safety protection technology at the end of the power grid, can be used to prevent accidents such as personal electric shock and death. [0003] At present, the online residual current protection device uses the detected effective value of the leakage current as the only criterion for performing a tripping action. But actual experience shows that there are insurmountable shortcomings in using the effective value of leakage current as a criterion for implementing electric shock protection. For example, when the residual current protection device is running on a grid with unbalanced three-phase leakage current, there are insensitive phases (that is, dead zones without electric shock protec...

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Problems solved by technology

For example, when the residual current protection device operates on a power grid with unbalanced three-phase leakage current, there will be an electric shock insensitive phase (that is, an electric shock unprotected dead zone) and an oversensitive phase (false action zone), so the protection characteristics are not ideal, affecting Operation rate of residual current protection device and reliability of safety protection

In addition, my country's power supply grid, especially the rural power grid, due to different reasons such as grid, equipment, power consumption, insulation aging, etc., even in normal operation mode, the normal leakage current of the grid power supply circuit may reach several to hundreds of milliseconds. An, exceeding the setting value of the residual current protection device, false tripping occurs, which greatly reduces the reliability of the residual current protection device and the correct operation rate, and even causes problems such as failure to operate

[0004] The above defects show that taking the effective value of the leakage current as the criterion for whether to perform the tripping action will cause the residual current protection device to trip by mistake, especially the current protection device that should not trip when no people or animals get an electric shock because the effective value of the leakage current Larger causes false tripping, reduces the reliability of residual current protection, and affects the normal power supply of the power supply grid

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