Power System Harmonic Detection And Suppression Based On Dual Observer

As the harmonic pollution in the power system becomes more and more serious,it has caused a wave of research and treatment of harmonics at home and abroad.In order to selectively compensate the harmonics of the power grid,this article focuses on the research of the following two parts: First,the research on harmonic detection.This paper proposes a new harmonic current detection method based on the dual observer theory,which meets the requirements for real-time and accuracy of specific sub-harmonic detection,and provides a new idea for the traditional harmonic detection method;Second,the research on tracking control of harmonic currents.This paper designs a space voltage vector conversion method based on multiple PR control for the harmonic current tracking control,which is mainly aimed at the low-order harmonics with serious pollution in the power grid,which can improve the dynamic response performance of the system;Finally,the feasibility of the method proposed in this paper is verified by simulation.The methods and innovations used in this article are as follows:A method of harmonic extraction based on dual observer is proposed.By designing an auxiliary filter,a set of variables related to the frequency of each harmonic is obtained,and then the harmonic signal of the power grid is expressed as a function of a measurable signal and the same frequency as the fundamental wave signal of the power grid;At the same time,a dual observer is designed to estimate this function,and the fundamental signal of the power grid is re-described.This method can express the harmonics through auxiliary variables,realize the separation of the fundamental wave signal and the harmonic signal in the power grid,and has a more accurate detection effect than the traditional instantaneous reactive power theoretical detection method.When there is no bounded interference,this observer can track the fundamental frequency signal asymptotically.In a multi-source interference environment,the parameters of the auxiliary filter can be adjusted to ensure that the interference error is dynamically consistent and ultimately bounded.The current tracking control adopts the space voltage vector transformation method based on multiple PR,focusing on the tracking control of the low-order harmonic current,and compares it with the traditional hysteresis current control.Through simulation analysis,it is determined that this current tracking control method has good performance in terms of accuracy and dynamic response speed,and it also reduces the number of switching times and reduces the loss.The APF simulation model is built using the above method,and the simulation parameters are calculated and selected,and the APF is completed to compensate for specific sub-harmonics.Through the simulation analysis of the harmonic compensation results,it is verified that the proposed method meets the requirements of full harmonic compensation,selective harmonic compensation and compensation under different working conditions.In summary,the APF designed in this article has ideal compensation accuracy and can respond quickly under sudden load changes.