Research On Without Counter-reverse Parallel Power Supply Technique Studies Of Photovoltaic Power Supply

Owing to the glasshouse effect caused by excessive carbon release and the threat of extreme climate,photovoltaic power generation technology has developed rapidly in recent years.Nowadays,there are two main application approaches: one is that without charging battery,represented by photovoltaic grid-connected power generation;another is the way of charge-discharge,generally used in off-line power supplies when power connection is inconvenient,with high cost of electric storage.If the charge-discharge approach is applied in the place where the power line is available,the saved electricity will not even compensate the cost of the battery.Photovoltaic grid-connected technology can save battery cost,but the requirements of direct grid-connection are very strict.Amplitude,frequency,phase,harmonic content and other parameters are required to strictly meet the grid-connected requirements,so it is more suitable for centralized photovoltaic power plants.Small distributed photovoltaic power plants can effectively utilize the idle space of buildings,but the grid-connected parameters are difficult to reach the standard.With the wide use of such small power plants,the power quality and stability of the power grid have been adversely affected.If the photovoltaic power supply is spontaneously used at the user end and the excess electricity is not fed into the power grid,this non-reflux power supply is a relatively efficient photovoltaic application scheme.This work analyzes the characteristics of solar cells as well as the advantages and disadvantages of conventional photovoltaic power generation inverter circuit topology.Aiming at the problem that the output of small and medium-power photovoltaic power sources is unstable with the change of sunlight,a joint power supply system is designed that uses solar energy for assistence.The inverter system is connected to the AC power without reverse current,only supplying power to the load.Thus batteries are saved.The inverter output has the same frequency and phase as the AC power supply.Based on the previous unidirectional coupling technology of photovoltaic and AC power supply of our laboratory team,an improved unidirectional isolation anti-reverse-current circuit was designed,which enables the AC power input to achieve a full angle of conduction,ensuring that the photovoltaic inverter and the AC power supply in parallel not flowing back into the grid,and reducing the circuit loss.According to the analysis of the inverter topology,the design of the inverter system in this work adopts the two-stage high-frequency chain structure and the single-stage high-frequency chain structure,respectively,to jointly verify the adaptability and effectiveness of the anti-reverse current system.The two-stage high frequency link scheme increases the solar cell voltage to DC high voltage through push-pull boost DC/DC circuit,and then outputs sinusoidal AC through full bridge high frequency DC/AC circuit transformation.The single-stage high-frequency link scheme outputs one-way sinusoidal half-wave synchronous with AC power by push-pull DC/DC circuit high-frequency conversion,and then outputs sinusoidal alternating current by full-bridge power frequency change direction.Finally,the AC outputs of these two schemes are powered by one-way isolated anti-reverse current circuit and parallel power supplies.The experimental results of pure hardware AC auxiliary power supply system built in this paper show that: The efficiency of the single-stage high-frequency link inverter scheme is better than that of the two-stage high-frequency link scheme,but both can work stably and reliably.The whole system can operate stably under different load conditions.The use of photovoltaic energy saving at the same time avoids the complex grid connection technology,and realizes the function of no countercurrent parallel but not into the grid.