Abstract: In the power supply and distribution system of steel enterprises, the proportion of impact loads such as electric arc furnaces (EAFs) and rolling mills is high. Voltage fluctuations, harmonic pollution, and frequency instability in isolated grids have become key bottlenecks restricting the production of high-quality special steel. Based on a special steel complex with an annual production capacity of 12 million tons, this paper systematically analyzes the mechanisms of voltage sag, flicker, harmonic resonance, and power angle instability in isolated grids caused by impact loads from the perspective of power quality, and establishes a simplified quantitative model. On this basis, an EAF load prediction method based on long short-term memory (LSTM), a coordinated control strategy for ±80 Mvar chain-type SVG and arc suppression coil, and an underfrequency load shedding scheme optimized through PSD-BPA isolated grid N-1 fault simulation are proposed. Engineering applications show that after the transformation, the voltage qualification rate of the 110 kV busbar increased from 89.3% to 99.6%, the total harmonic distortion (THD) decreased from 9.2% to 2.1%. The frequency recovery time in the isolated grid was shortened from 120 s to 45 s, the correct operation rate of relay protection increased to 99.5%, and the unplanned downtime decreased by 72%. The research results can provide a reference for the power quality management and stable operation of industrial power grids with a high proportion of impact loads.