Comprehensive Evaluation And Treatment Of Power Quality Of AC/DC Hybrid Distribution Network

As the contradiction between the increasing global energy demand and the depletion of traditional fossil resources is becoming more and more prominent,the contradiction between the ever-changing power supply,load form and the safety and stability of the power grid is becoming more and more serious.AC/DC hybrid distribution network has become the development direction of the next generation distribution network because it can reduce losses,improve system reliability and economy.Since the AC and DC in the hybrid distribution network has interactive influence,and the power quality status of each node in the distribution network will affect the comprehensive assessment of power quality,this paper studies the following situation:Firstly,in order to clearly explain the complexity of power quality in the hybrid distribution network and the particularity of the evaluation object,the theoretical and simulation analysis of the interaction between the AC and DC sides of the inverter in the hybrid distribution network is carried out.By injecting harmonics of different frequencies on the AC side and changing the initial phase of the harmonic power supply,and performing harmonic analysis on the AC/DC side power,the analysis results show that when the power supply voltage has harmonics or three-phase unbalance,the inverter pays The DC side will interact interactively.Secondly,the model of AC/DC hybrid distribution network is established,and the power quality index of hybrid distribution network is set according to the concept of “source-network-load”.For the harmonic control in power quality,the comparison and analysis results of simulation experiments show that the hybrid power filter has a good governance effect.Finally,based on the power quality of each node of the distribution bus,it will have a certain impact on the power quality assessment of the distribution network.This paper proposes the node-line correlation weight method to express the importance of each node.Because of the existence of AC and DC power quality indicators in the hybrid distribution network,this paper assigns weights to the AC and DC nodes by combining weights and objective functions to achieve the comprehensive assessment of power quality of hybrid distribution networks.The simulation example measures the value of each node's power quality index,and the node-line correlation weight method is used to evaluate the power quality.