Research On Data-driven Controlled Paralleled Inverters In Microgrid

Microgrid is composed of a number of distributed power generation units,the paralleled inverters’ control is one of the key technologies as inverters are core devices in power generation.In this paper,the paralleled inverter in microgrid is taken as the research object,and the limitation of droop control based on inverters’ mathematical is analyzed.The model free adaptive control method is proposed which can compensate itself for the loss of data transmission.And predictive control is applied in preceding stage to optimize the dynamic performance of data-driven controller.Finally the simulation model is established to verify its effectiveness.Firstly,the importance and key issues of parallel operation of inverters in microgrid are introduced,as well as the application status of data-driven control in power converters.The essential difference between existing paralleled inverters’ control schemes and the data-driven control is whether the design of the controller requires the physical mechanism model of the inverter.Secondly,taking the droop control as an example,the existing problems of the control method based on the inverter mechanism model are illustrated.By analyzing its inherent flaw in paralleled inverters’ control,that is,when controlling distribute the common load power equally within each inverter,the droop coefficient is strictly limited,and the design of voltage-current dual closed-loop depends on the inverter’s own parameters,all of these above makes the droop control have unmodeled dynamics issues.Thirdly,the model free adaptive data-driven control for a single inverter in microgrid is proposed.An approximate linearization model of the inverter is obtained by introducing a dynamically changing parameter:pseudo-gradient vector.This model don’t require the mechanism model information,the control law is designed using only the input and output data,and the stability of the designed data-driven controller is analyzed.The dynamic update of the pseudo-gradient vector is also obtained from the input and output data.Then,adding the related term to the dynamic linearization model of a single inverter makes it suitable for paralleled control,and in this paper we put forward to applicate droop control to obtain the input and output data of a single inverter in steady state operation.Using these stable data operations the initial value of the pseudo-gradient vector and the correlation matrix of the data-driven controller are obtained,so that a single inverter can be incorporated into the microgrid in a modular form.The data-based compensation measures are gave when the data transmission is lost,and the model predictive control scheme is added in to optimize the robustness.Finally,three paralleled inverters’ simulation model is set up in Matlab/Simulink software.The simulation experiments of changing the parameters of common load and inverter are designed.The control performances of the droop controller and the proposed data-driven controller are compared.It is verified that the proposed method has better robustness and can adaptively adjust the control parameters to deal with the parameter changes of the inverter parallel operation system.It is of certain reference value for the further research.