When Harmonic resonance strikes a grid

When Harmonic resonance strikes a grid, at its 33kV power distribution system, it results in a massive total voltage harmonic distortion, THDv magnification, within the affected power system at the grid supply zone. The order or number of individual voltage harmonics, are around the grid's natural resonance frequency range. It results in a large voltage oscillation, and fluctuations in the forms of simultaneous incidents of voltage sags and swells.