Active Disturbance Rejection Control Technology Of Grid-Connected Inverter Based On LTCL Filter

New energy power generation has the advantages of clean,green and sustainable,which is in line with the strategic direction of national development.The representatives of new energy sources such as wind energy and solar energy,whose distribution characteristics determine that it is difficult for new energy power generation to adopt centralized power generation.In addition,although the power supply of the large power grid is still the most important power supply method at present,as the society's reliability requirements for energy power supply are getting higher and higher,the distributed power generation system is obtained as a reasonable supplement to the large power grid due to its decentralized and flexible characteristics The growing importance.The grid-connected inverter is a key part of the successful combination between the two.It is related to the power quality of the grid-connected current.The robustness of the grid voltage distortion and weak grid has also received more and more attention.In this paper,for the grid-connected inverter system based on LTCL filter,the natural resonance of the filter and the device parameter drift are compensated and suppressed.After analysis,it is equivalently simplified to achieve reduced order.The phase-locked loop of the pre-filter ensures the robustness of the system.The network filter is an indispensable part to ensure the power quality,and considering the resource extraction leads to the continuous increase of copper price,in order to improve the cost performance while ensuring the filtering effect,this paper uses a higher order LTCL filter.However,while enhancing its performance,the insertion of the LC branch will undoubtedly cause the resonance problem to be more serious.In this paper,in consideration of the actual parameter error,it is designed in detail,and the passive resonance method is used to achieve of inhibition.To solve the problem of complicated control parameter design caused by high system order,through analysis of each high-order filter,it is found that series resonance does not increase additional control difficulty.After comparing the transfer function Bode diagram,the LTCL filter can be used equivalent simplification and reduced order.After that,the grid-connected inverter system model was established in the dq coordinate system,and the coupling phenomenon was analyzed and discussed.The grid-side current is controlled by LADRC.Compared with traditional control methods,the biggest advantage of ADRC is that it has got rid of the mandatory requirements for accurate models.After linearizing it,it adopts a simpler parameter tuning method and comprehensively considers the limitations of the delay link to the observer bandwidth Under the conditions,select a set of parameters with the most comprehensive performance.The DDSRF-PLL phase-locked loop using a pre-filter ensures that the phase-locked loop can accurately lock the phase of the grid voltage under grid voltage distortion and weak grid conditions.Then,in the simulation environment,the overall robustness of the system was verified.By comparing with the traditional PI control,the advantages of LADRC were established and the ideal control effect could be achieved.