Microcomputer harmonic elimination can quickly analyze the frequency component of power grid resonance by collecting Pt open triangular voltage, and accurately judge single-phase grounding and power grid resonance. If it is resonance, the computer sends a command to put the harmonic elimination circuit into operation to realize rapid harmonic elimination. The actual operation shows that the device can accurately judge various high-frequency, low-frequency and common frequency resonances, act quickly, perfectly solve the resonance overvoltage problem of the power grid in the power system, and can store and record the resonance times and resonance frequency.

        The microcomputer harmonic elimination device adopts the microcomputer harmonic elimination technology. The input damping resistance is determined according to the harmonic frequency of the open triangle of the voltage transformer and the zero sequence voltage. It is mainly divided into two parts: harmonic elimination element and microcomputer control part. Among them, the harmonic elimination element is a damping device to protect the primary side of the voltage transformer, which is used to eliminate the resonance in the power grid.

        As a protective device, it is usually made of resistance, thyristor material and solid-state relay. It is generally connected in series in the open triangle. When the voltage of a certain frequency reaches a certain value, the bidirectional thyristor connected to the open triangle or zero sequence PT secondary coil is turned on, and the open triangle or zero sequence PT secondary winding is short circuited to generate strong damping at the open triangle side and eliminate resonant overvoltage. In order to distinguish single-phase grounding, the basic frequency starting voltage value is generally set as a certain threshold, and the basic frequency overvoltage below this threshold will not start. Generally speaking, whether resonance, overvoltage, undervoltage or other phenomena occur, the detection circuit of the device can detect all its information, and then play the role of harmonic elimination. The key of intelligent microcomputer harmonic elimination is to correctly distinguish between fundamental resonance and single-phase grounding.