Large-scale wind power ramp events(WPRE)have a significant impact on the power balance of power system and may lead to load shedding in severe cases. Interval analysis method is introduced to establish a multi-level early warning method for WPRE

by which the warning information can be provided to reflect the degree of potential harm inflicted by WPRE. According to the characteristics of WPRE

the number of intervals is introduced to describe the uncertainty of wind power. In view of the impact of large volatility of WPRE on power control and with the static frequency deviation maintained within the allowable range as precondition

the permissible intervals of ramping amplitude are analyzed to determine the boundaries between different warning levels corresponding to different power control measures. Comparison of the boundaries with the prediction results of wind power

multi-level early warning for WPRE shows that the interval ranking method can provide the probability distributions of different warning levels. Simulation results and comparative analysis demonstrate that

both the boundaries and probability distributions of different warning levels

with clear physical meaning

can be provided by the simple and rapid method beneficial to real-time scrolling operation and testifying to the effectiveness and practicability of the proposed method.