Bus Voltage Control Based On Improved ADRC Grid-connected Photovoltaic Inverter

Nowadays,with the rapid development of global economy and the continuous progress of science and technology,people’s demand for energy is increasing.At the same time,energy shortage and environmental problems have become difficult problems that must be solved.In order to solve these problems,new energy(such as photovoltaic,wind power)as a clean and environmental energy has attracted worldwide attention.Due to the abundant solar energy storage,green environmental protection by the world’s key development.Photovoltaic technology promises a more rational approach to solar energy.However,due to the randomness and volatility of photovoltaic power generation,it is easily affected by external environmental factors(illumination intensity,ambient temperature).Therefore,in order to improve the disturbance immunity performance of photovoltaic power generation system,the selection of appropriate control strategy has become a crucial link.The grid-connected photovoltaic inverter is an important power electronic converter to realize the DC-AC conversion in the photovoltaic power generation system and plays a decisive role in the grid-connected power generation.In the photovoltaic power generation system,the quality of grid-connected power and the operating efficiency of the system depend on whether the photovoltaic power generation system has good control effect.In this paper,the two-stage photovoltaic power generation system is studied.Taking the grid-connected photovoltaic inverter as the controlled object,the ADRC technology with strong disturbance rejection performance is selected to improve the disturbance rejection performance of the photovoltaic power generation system.In this paper,the photovoltaic grid-connected inverter is modeled in a three-phase static coordinate system and a two-phase synchronous rotating coordinate system,and the control strategy of the photovoltaic power generation system is analyzed.Aiming at the shortcomings of poor anti-disturbance performance of traditional control strategies,ADRC technology is introduced into photovoltaic power generation systems.Based on the traditional active disturbance rejection control theory,the extended state observer is improved using the principle of deviation control,and the new deviation between each state variable and its observation value is used as its adjustment basis to obtain higher observation accuracy.The frequency domain analysis method is used to compare the anti-disturbance performance of the improved active disturbance rejection controller and the traditional active disturbance rejection controller,and construct a Lyapunov function to analyze the stability of the improved active disturbance rejection controller.It can be seen from the amplitude-frequency characteristic curve that although the phase lag in the mid-frequency band of the improved LESO has been significantly improved,the high-frequency band is basically the same.In order to obtain better high-frequency attenuation capability,this article uses the series correction method to add a first-order inertia link to the total disturbance channel.From the amplitude-frequency characteristic curve,it can be seen that the LESO-CL with the correction link has better High-frequency attenuation ability,and finally the stability conditions of LADRC-CL are given using the Linard-Chipart stability criterion.Finally,a photovoltaic power generation system model was built on the Matlab/Simulink simulation platform.Through simulation under multiple working conditions,the LADRC-CL combined with the correction link and the improved LADRC control strategy based on the deviation control principle were studied.Verify the effectiveness of the control strategy proposed in this article.