Research of DPLL for photovoltaic grid-connected power generation system

RUAN Xing
（Fujian Inspection and Research Institute for Product Quality， Fuzhou 350002， China）

Abstract：Aiming at the shortages of the use of conventional analog phase-locked loop in photovoltaic grid-connected power generation system，the use of digital phase-locked loop in photovoltaic grid-connected power generation system was analyzed，the working principle and control strategy were described in detail，the design process of the relevant circuit parameter was presented，and software simulation was carried out based on Matlab. For the distortion，sudden increase，sudden reduction in voltage in actual power grid，corresponding anti-jamming test was carried out in simulation. And ultimately，the control strategy on a 6 kVA experimental prototype was experimentized. Experimental results and waveforms show the validity of the scheme. Digital PLL uses digital control technology instead of conventional analog control technology，besides reducing the cost of photovoltaic grid-connected inverter，high output performance is insured. It can make the grid-connected inverter generate power to the grid with high power factor and anti-islanding protect reliably，it also can reduce the complexity in the debugging of actual system.
Key words： photovoltaic system； digital phase-locked loop（PLL）； high power factor； digital signal processor（DSP）