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With the rapid development of power electronics technology, a large number of nonlinear devices are widely used in power network, industry and home, and the harmonic problem has attracted more attention. In the distorted power system, it is the premise of harmonic pollution control to clarify the shared harmonic responsibility of the system side and each user at the common connection point. The existing liability division methods mainly focus on a certain harmonic, and the results are difficult to reflect the actual harmonic influence of users. The direct effect of harmonic problem can be measured by economic loss, which is the main basis for the division of harmonic responsibility is beneficial to the implementation of reward and punishment measures. This paper presents a harmonic liability division method considering the effect of user harmonic on economic loss. Firstly, the harmonic compatibility level of users is graded considering different proportions and different types of equipment. Secondly, reference to the national standard to develop economic indicators to measure the impact of harmonics on users at all levels; Finally, each harmonic responsibility of the system side and the user side is calculated, and the final comprehensive harmonic responsibility index is obtained by combining the economic index of each user harmonic influence. The reasonableness of this method is verified by the measured harmonic data of users connected to a substation.

This article provides a critical overview of problem‐based learning (PBL) practice in dental education in China. Because the application of PBL has not been carried out on a large scale in Chinese dental education, this review was performed to investigate its effectiveness. Databases were searched for studies that met the inclusion criteria, with study identification and data extraction performed by two reviewers independently. Meta‐analysis was done with Revman 5.1. Eleven randomized controlled trials were included. The meta‐analysis found that PBL had a positive effect on gaining higher theoretical (SMD=0.88, 95% CI [0.46, 1.31], p<0.0001) and practical scores (SMD=1.48, 95% CI [0.95, 2.00], p<0.0001). However, the pooled result did not show any positive effect on gaining higher pass rates (RR=1.06, 95% CI [0.97, 1.16], p=0.21). This meta‐analysis suggests that the PBL pedagogy is considered superior to the traditional lecture‐based teaching in this setting. PBL methods could be an optional supplementary method of dental teaching models in China. However, Chinese dental schools should devise PBL curricula according to their own conditions. The effectiveness of PBL should be optimized maximally with all these limitations.