Research On Detection Technology Of SVG Under Unbalanced Operation Modes

With the increase of the complexity of loads,a large number of reactive power,imbalance and harmonic currents are brought to the power grid,resulting in serious power quality problems.The SVG device is an important equipment for power quality control.The accuracy of the detection is related to the performance of the entire device.At present,there are mature methods such as p-q method,ip-iq method,etc.These methods have some limitations in the three phase unbalanced operation mode.It is of great significance to study the full parameter detection that can detect all unbalanced components.A full parametric detection method based on the trigonometric transformation method is proposed,which can not only detect fundamental positive active and reactive currents,but also negative and zero sequence active and reactive currents,providing the basis for the comprehensive detection and refinement compensation of SVG systems in three-phase unbalanced conditions.The Matlab/Simulink simulation platform is used to verify the correctness and superiority of the method.The characteristics of the existing three-phase software phase-locked loop are researched,the shortcomings of the existing methods are analyzed,a delay cancellation PLL method is analyzed,the mechanism of the delay cancellation is studied,and improvements are made in this method.In the new method,the delay time is reduced from T/4 to T/8,and the dynamic response speed of the PLL is improved effectively.Compared with the traditional SRF-PLL and delay elimination method,the validity of the improved delay cancellation PLL in three-phase unbalanced system is verified.Compared with the characteristics of existing SVG architectures,a detection scheme of FPGA+DSP architecture is proposed.The improved delay cancellation PLL is implemented on FPGA and the full parametric detection algorithm based on trigonometric transformation is implemented on DSP.The hardware and software design of the experimental prototype and the construction of the experimental platform are completed.The experiments verify the correctness of the signal conditioning function,data sampling function,phase lock function,and parameter detection function.The experimental results conform to the expectation.