Abstract
In this paper, the basic principle and characteristics of a phase-locked loop (PLL) in a single phase grid-connected system are analyzed, and this paper introduces one type virtual orthogonal voltage vector method based on a third order generalized integrator (TOGI) to construct an alpha and beta static coordinate system. The TOGI structure can eliminate the DC offset in a voltage signal or zero offset in the sampling process, and ensure the amplitude of the virtual orthogonal signal is consistent. At the same time, the adaptive frequency estimation unit is introduced, which can effectively deal with the power grid voltage frequency changes and ensure the accuracy of PLL. MATLAB (R2012a, MathWorks, Natick, MA, USA) is used to simulate the variation of power grid voltage frequency, DC component injection, harmonics injection and other parameters, and the performance of PLL is adequately verified. In addition, a 5kW single-phase energy router experimental platform is built to verify the proposed PLL. The experimental results show that the PLL can well track the frequency change of the grid voltage and eliminate the DC offset, so as to achieve accurate phase tracking.
Highlights
With the introduction of the Energy Internet and the continuous development of power electronics technology, the architecture, theory, technology and application research of the generation of smart power distribution networks with key equipment power routers have become more and more a hot topic in the field of renewable energy [1,2]
(2), it can still be seen that the difference between the transfer system with the direct current (DC) offset and flexibility input reference, this paper presents a new adaptive frequency function of second order generalized integrator (SOGI)-frequency locked loop (FLL)
The adaptive frequency phase-locked loop (PLL) based on third order generalized integrator (TOGI) is verified by an experimental test platform, which is a single-phase 5-kW bidirectional energy router equipment unit based on main control by a TMS320F28335 DSP and Xilinx FPGA Spartan6 LX9
Summary
With the introduction of the Energy Internet and the continuous development of power electronics technology, the architecture, theory, technology and application research of the generation of smart power distribution networks with key equipment power routers have become more and more a hot topic in the field of renewable energy [1,2]. Considering the DC offset, harmonic distortion and estimation in the PLL single-phase structure to realize frequency adaptive. Reference [22]involve studiedthe theFLL frequency estimation unit in the PLL in of single-phase SOGI structure to realize frequency adaptive. The SOGI achieves high reliability to synchronize the fundamental signal of the frequency adaptation, but it cannot realize the DC offset elimination, so a PLL based on a novel OSG power grid, and track the phase angle, it has the drawback that limits its application in practice. Based on the above analysis, we need to reconstruct the conventional SOGI to eliminate the DC signal and generate an adaptive frequency reference
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