Due to the volatility of renewable energy output,the power grid with high proportion of renewable energy integration frequently faces the power quality declining.This reduces the operation efficiency of sensitive load and further leads to abnormal operation or even malfunction of equipment.In this background,the load loss may occur when the voltage falls to the uncertain region of the sensitive load voltage tolerance curve,which should not be neglected.Such load mode possibility should be considered for the distribution network planning in order to improve the security and economy of the power grid.In this paper,the frequency variable motor is taken as a typical load to model and analyze in terms of its voltage sensitivity.First,the fault probability of the frequency converter in the uncertain region of the voltage tolerance curve is estimated,and then the loss of voltage sensitive load is calculated and incorporated into the distribution network risk planning model to improve the adaptability of the existing method.The results of the test example verify the feasibility and effectiveness of the proposed method,which will be a reference for the future distribution network planning.