Abstract: Studies a voltage abnormality event is studied in the 330kV step-up substation of a certain wind-solar-storage hybrid power plant.In January 2025, the 330kV bus voltage of the plant surged to 368kV, causing equipment damage. Analysis shows that the direct causes were the out-of-control fluctuation of the station service system due to the SVG communication power supply not being connected to a UPS, and the high-frequency oscillation triggered by the high-frequency negative resistance characteristics of the SVG and the capacitive impedance of the no-load cable. A monitoring system of "FFT early warning + wavelet analysis" is proposed to adjust the output characteristics of the SVG in real time through algorithms such as adaptive control and model predictive control, enhance system damping in the 1.5~4kHz frequency band, and suppress negative resistance characteristics. Meanwhile, a reactive power coordinated control strategy for multiple devices is established. Based on the voltage sensitivity formula and the principle of reactive power priority regulation, collaborative compensation among wind turbines, photovoltaic systems, energy storage, and SVG is achieved. The problem of high-frequency negative resistance-capacitance resonance is solved through hardware technical transformation and algorithm