Purpose. To substantiate the expediency of applying distribution laws to model the reliability of power supply systems with powerful nonlinear loads. Methodology. Application of exponential and normal distribution laws, and Weibull's law. Findings. In a comprehensive assessment of the problem of electromagnetic compatibility and the development of multicriteria parameters of energy efficiency of power supply systems of industrial enterprises, it is most appropriate to use the reliability of the elements that are mathematically described by the Weibull distribution. At the same time, the results of modeling of typical electrical modes and variations of substitution schemes of enterprises showed the sensitivity of reliability indicators to changes in power system capacity. Originality. New theoretical foundations for research in modern power supply systems with increasing nonlinear load capacity have developed the scientific basis for analysis and synthesis of energy processes in multiphase electrical systems and propose methods of correction taking into account the complex action of sources of electromagnetic interference. And also to offer methods of estimation of their influence on reliability and efficiency of work of the basic electrotechnological equipment. Practical value. The possibility of applying the obtained results to assess the reliability of power supply systems with powerful nonlinear loads is substantiated. The necessary accuracy and reliability of the decision at the levels of random events, quantities and processes is provided. The mathematical apparatus for the analysis of the main indicators of reliability in the presence of non-sinusoidal voltage is given. Conclusions are made on the adequacy of the calculation results at different stages of electricity distribution. It is shown that the simultaneous optimization of reliability and voltage quality are components of a complex scientific problem of ensuring energy efficiency of electrical networks in the implementation of decentralized models of the energy system.