With the development of renewable energy and energy storage technology, the trend of power electronics in power distribution systems has become more obvious. Harmonics is an essential indicator of power quality, but there are still many obstacles and challenges in the practical application due to lacking standardization. Considering the multiple practical conditions and various user power demands, a new metric recommended for the harmonic standard of power electronic distribution systems is proposed in this paper. Firstly, this paper makes a comparative study of IEEE and domestic harmonic standards in many countries. Secondly, the separate causes of harmonics generated by renewable energy are analyzed relying on the actual measurement data from a wind turbine (WT) grid-connected inverter. Then, the shortcomings of the current standard system are pointed out. Finally, this paper proposes an additional harmonic standard that adapts to various operating conditions and makes additional provisions for special equipment and different users.