Harmonic Assessment of the Distribution Network based on Load Type Classification (Field Study)

One of the main and important problems of power quality in the power distribution network is harmonic pollution. Understanding and quantifying the level of harmonics in the network is very important before proposing any suitable method to reduce the harmonic problems in the network as well as the network development plan. In this regard, in this paper, according to the classification of customers in the power distribution network and based on the most significant number of customers in the network, electrical loads are classified into four categories: residential, commercial, office, and combinatorial. Then the harmonic evaluation of the power distribution network for each type is carried out. In order to make the evaluation more operational and practical, two new harmonic indices are proposed as well as a new way of expressing the total current harmonic distortion. Considering that it can be assumed that each type of loads injects similar harmonics into the network, analyzing the measurement results for each type of load shows the harmonic behavior of each type of load in the distribution network to a large extent, which in the development and loading of distribution substations is very useful. According to the results, the current harmonic distortion of the load types is categorized as 1. office 2. commercial 3. residential 4. combinatorial in order from high to low. Based on this, it is possible to consider the range of harmonic factor K for combinatorial loads around 3, residential loads around 3.5, commercial loads around 5, and office loads around 11. Simulation results using MATLAB software show that third-order harmonic compensation can improve the total current harmonic distortion for office, residential, and combinatorial loads by up to 40%, and for commercial loads by up to 30%.