The electromagnetic voltage transformer in the 6-35KV neutral point ungrounded power grid will cause the voltage transformer to be oversaturated when the busbar is empty or appears less, due to the ground fault elimination during the closing charging fire operation, etc. It may produce ferromagnetic resonance overvoltage. Unstable voltage relative to the ground, misoperation of the grounding indication, blown of the voltage transformer high-voltage fuse, etc., will cause the voltage transformer to burn out in severe cases, and then cause other accidents. A direct threat to the safe operation of the power system requires the installation of a microcomputer harmonic elimination device.

There are many iron-core inductance components in the power system, such as transformers, voltage transformers, arc suppression and parallel compensation reactors. These are mostly non-linear components. They and the capacitance of the system form many complex oscillation circuits. If certain conditions are met, It can excite a long-lasting ferromagnetic resonance overvoltage. The relatively high overvoltage and relatively large overcurrent generated during the occurrence of ferromagnetic resonance can easily damage the insulation of power equipment and endanger the safety of operators in severe cases.

The microcomputer resonance elimination device monitors the voltage and frequency at the opening triangle of the voltage transformer measurement and control device in real time. When ferromagnetic resonance occurs, the device instantly activates the non-contact resonance elimination component to generate strong damping, thereby eliminating the ferromagnetic resonance.

The microcomputer resonance elimination device uses the computer's fast and accurate data processing capabilities to achieve fast Fourier analysis. Its frequency selection is accurate. Through the collection of the open triangle voltage of the voltage transformer, the various frequency components of the grid resonance can be quickly analyzed and accurately Identify: single-phase grounding, filtering process, grid resonance. If it is resonance, the computer will issue instructions to activate the resonance elimination circuit to achieve rapid elimination. The actual operation proves that the device can accurately judge various high-frequency, low-frequency, and power-frequency resonances, and act quickly, which perfectly solves the problem in the power system. The harmonic elimination problem of the power grid, and can record and store the number of resonances and resonance frequency.