Microcomputer protection method for preventing maloperation caused by electromagnetic interference

Abstract

The invention relates to a microcomputer protection method for preventing maloperation caused by electromagnetic interference, which can lock a corresponding protection function when a microcomputer protection device is subjected to electromagnetic interference or encounters excitation surge current and can release the locking in time at the end of the interference. Compared with the prior art, the method can accurately and timely identify abnormal waveforms and lock the protection function of the device, and can release the locking of the protection function in time after the abnormal condition is over, thereby providing an accurate and reliable basis for fault judgment of protection logic. In addition, the method is applied to the production field and obvious in effect.

Description

technical field [0001] The invention relates to a microcomputer protection method, in particular to a microcomputer protection method for preventing malfunction caused by electromagnetic interference. Background technique [0002] Microcomputer protection technology means that when the microcomputer protection device detects that the current or voltage of the protected object exceeds or falls below the set value due to faults such as short circuit, the protection device performs logical judgment, enables the outlet relay to operate, and drives its corresponding circuit breaker Carry out tripping action to remove the corresponding fault. [0003] For the line protection function, the microcomputer protection device converts the collected analog current signal into a digital signal, that is, a sampling value, and then calculates and judges according to the sampling value. [0004] A complete set of overcurrent protection consists of three sections of overcurrent protection: o...

AI Technical Summary

Problems solved by technology

The excitation inrush lasts for a long time, ranging from dozens of power cycles to tens of seconds, so the excitation inrush often causes the overcurrent protection function of the microcomputer protection to malfunction

[0009] In order to prevent the malfunction of microcomputer protection caused by electromagnetic interference, it is common practice to install filter components or shielding materials on the hardware of microcomputer protection, but the processing cost is high and the effect is not ideal.

[0010] In order to prevent malfunction of microcomputer protection caused by excitation inrush current, differential relays with fast saturated iron cores are generally used on hardware, but their disadvantages are high cost and unsatisfactory effect; second harmonic braking criterion is generally used on software, and real-time The calculation of the second harmonic will increase the load on the core processor of the microcomputer protection, and sometimes the effect is not ideal; in addition to the second harmonic braking method, some microcomputer protection manufacturers also use a fixed delay scheme, that is, when detected When overcurrent occurs, the device executes the judgment after a delay of several cycles, but this method will cause the action time to be too long when there is a real need for instantaneous current quick-break protection, which cannot play a reliable protective role.

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