The Research On Software Phase Locked Loop Of PV Grid-connected Generation System

In the world,there was big opportunities and challenges in development andutilization of new energy. For achievement of sustainable development in the word.human must more economical, convenient and efficient to using the energy.The solarpower play an significance role in development of new energy,And solar power grid isan important development trend.In order to prevent the transient current in power griddamage the power generation system,the power grid system need to using the phaselocked loop,which can tracking the frequency and phase of the grid voltage, then adjustthe intever’s current,so that it can be incorporated into the grid effectivly. The importantfactor affect of grid system stability is phase-locked accuracy and lock-in speed. Intraditional technique,there was contradiction in the phase-locked accuracy andphase-locked speed.It is worth to study an algorithm that both can improve thephase-locked accuracy and the lock speed.This paper used TI’s TMS320F2812as the main circuit control chip.for settinginternal event manager’s cycle register TIPR and the value of the compare registerCMPR, it can generates a triangular carrier and sinusoidal modulation wave, Sinusoidalpulse width modulation control output inverter current. Using the voltage transformerscollecting grid voltage to obtain the phase and frequency information, and then usingthe A/D conversion to calculating the phase difference and the grid frequency.Accordingthe calculated phase difference data,adjusted the phase of the network current. Thecycle of the triangular wave is changed by changing the F2812’s T1PR value.Thenachieve tracing output voltage phase.The paper introduction several state of the phase-locked loop, and usingMATLAB7.8simulation and analysis it.Comparison performance of analog PLL to thedigital PLL, and proposed the advantage of the software phase locked. In the design,the SPWM wave using asymmetric regular sampling method,In the software lockdesign, the approximation algorithm got relatively high precision but have the slowphase-locked speed, the optimal time phase locking algorithm can be completed phaselock in a single cycle,which got the fastest speed, but have the big overshoot. Therefore,the prior coarse after fine-tune algorithm taking into account the speed and theprecision of the phase-locked. Finally, complete the software design in CCS3.3development environment.