Research On Harmonic Compensation And Cooperative Optimization Of Multi-type Converters

With the development of society,new energy power generation has been widely used.On the one hand,new energy power generation increases the power of the power grid and reduces the consumption of primary energy.On the other hand,it also has a negative impact on the power grid.Among them,the harm of harmonics is one of the main problems affecting the power quality of the power grid.Therefore,harmonic control is necessary to maintain the stability and safety of the power grid.Distributed generation(DG)interface converters and active power filters(APF)can provide services such as harmonic compensation and reactive power compensation,which is conducive to improving the power quality of the micro-grid and saving costs.This article takes the interface converter and APF as the research objects,and aims at controlling harmonic pollution and improving the power quality of the microgrid.The following researches are mainly carried out:(1)In view of the problem that the DG interface converter and APF have different control modes,which results in high control complexity of the system,this paper achieves different types of converters by designing a unified harmonic voltage controller for the converters of different control modes.The controller can participate in the goal of coordinated regulation in a control manner in the microgrid.The designed converter based on the unified harmonic voltage controller uses the common voltage signal as the modulation variable,so as to avoid the measurement of the load side current.The simulation results verify that the different control mode converters are feasible based on the unified harmonic voltage controller design idea.(2)In view of the different output impedance of the converter,which leads to the difference in harmonic equalization capability and harmonic current sharing performance,this paper applies the theory of multi-agent and its consistency algorithm to the harmonic compensation of multi-type converters based on the analysis of the cooperative control principle,according to the relationship between the output impedance of the converter and the modulation signal,a current balancing control strategy of a multi-type converter is designed to realize the harmonics of VCM converter,CCM converter and APF.The compensation share is reasonably allocated to improve the harmonic current sharing performance,and the effectiveness of the strategy is verified by simulation.(3)In view of the limitations of the harmonic compensation of the interface converter and APF under different bus environments,and the different needs of different users for power quality,the node voltage distortion rate needs to be controllable,and the voltage quality of each node must be coordinated optimization.Therefore,a collaborative control method for node voltage quality index optimization is designed in this paper.The node voltage distortion rate is used to characterize the voltage quality of the node.A node voltage consistency algorithm with a weight coefficient is proposed to coordinate the voltage quality of different nodes according to the weight coefficient control,in order to solve the problem of demand differentiation of node voltage quality,and finally the simulation verifies the effectiveness of the algorithm.