Insulation Design Correction Method for Medium Voltage Variable Speed Electric Drive System in High-altitude Environment

In response to the critical deterioration of insulation electrical strength and voltage withstand capability of medium-voltage variable-speed electric drive systems caused by low atmospheric pressure at high altitudes, a study on the insulation design correction method for this system has been conducted. Employing a stepwise progressive strategy, firstly, based on altitude gradients and atmospheric pressure parameters, the altitude correction factors are deconstructed and coupled to achieve precise calibration of the insulation design correction coefficients. Secondly, using these coefficients as a basis, gradient reconstruction and quantitative correction are carried out for key insulation gaps within the system, thereby calculating the minimum safe distance under high-altitude conditions. Finally, with the aid of inverse mapping and tolerance threshold backtracking methods, based on the corrected gap values, the overall rated impulse withstand voltage and insulation coordination level of the system are verified. Experimental results show that this method can effectively suppress corona discharge and nonlinear growth of dielectric loss under low atmospheric pressure conditions, significantly enhancing the insulation reliability and operational robustness of the system under varying altitude gradients.