Research On New Three-phase Enhanced Phase-locked Loop

New energy power generation devices are connected to the grid in the form of distributed generation,and power is delivered to the grid through inverters and other equipment.Therefore,information such as phase angle,frequency,and amplitude of grid voltage must be accurately obtained.A phase-locked loop is usually used to track the fundamental frequency component of the grid voltage.Accuracy and rapidity are the key to the research of power grid synchronization information detection technology.This paper mainly studies the method of grid synchronization information detection under distorted grid.The specific work is as follows:(1)The performance of currently used Moving Average Filter(MAF),Cascade Delay Signal Cancellation(CDSC)filter and Multiple Delay Signal Cancellation(Multiple Delay Signal Cancelation,MDSC)filter are studied.To verify the equivalence of the three filters.Based on the general three-phase enhanced phase-locked loop(3P-EPLL)linearization model,a parameter design method for the control loop with in-loop filters is given.The advantages and disadvantages of in-loop filters.Through simulation,the advantages and disadvantages of adding in-loop filters are pointed out.(2)Aiming at the deficiency of 3P-EPLL with in-loop filter,a new three-phase enhanced phase-locked loop is designed.Compared with other methods,the Quasi-Type-I structure combines the CDSC filter with the type-I structure in the frequency loop,it can effectively improve the dynamic response speed of the system and eliminate the influence of grid voltage interference.Simulation and experimental results show that the new phase-locked loop can quickly and accurately track the frequency and amplitude of the grid voltage when the grid voltage is disturbed.(3)In order to reduce the computational burden,a new ??-EPLL is improved based on the QT1 structure is improved,and the MDSC filter is used in its control loop to further increase its dynamic response speed and reduce the amount of calculation.The resulting improved phase-locked loop not only has a small calculation burden,but also can deal with complex grid conditions and make synchronization signal detection faster.The effectiveness of the structure is verified by simulation and experiment.(4)In order to verify the effectiveness of the proposed phase-locked loop structure,the PLL proposed in this paper is used in the current detection link of the DSTATCOM,and its effectiveness is verified by building a simulation model.