In order to make a scientific analysis and increase the adaptability of the protective device, this paper introduces an assessment method based on loop analysis and Monte Carlo simulation. First, loop analysis is used to detect any variation in operating parameters in the distribution network. A voltage sensitivity matrix is established in order to get the sensitivity network loss for the distributed generation connected to the grid. A better three-point estimation algorithm is introduced for simplification of the probability calculations while a third-order polynomial normal transformation is used to standardize the arbitrary random variables. Moreover, the reliability evaluation of the protection device in the distribution network is conducted using the sequential Monte Carlo approach. At last, the probability distribution function of random variables is determined using the Edgeworth series expansion method. With the help of sensitivity assessment method based on loop analysis, dynamic detection of weak areas of the protective device can be carried out in the distribution network. Relative to the traditional Monte Carlo simulation, the reliability assessment of distribution network protection under the Monte Carlo simulation has a relatively small deviation and reaches up to 0.000% in the ASAI index.
