Research On Efficiency Optimization Of Photovoltatic Power Generation System

Photovoltaic technology and industry have been developed rapidly under the condition of current energy crisis. Although key technology in solar energy power generation is becoming more and more mature, some features such as high cost and low efficiency seriously influence its wide implementation. This paper purposes methods to improve the efficiency of solar energy system from two main aspects which exert influence on the efficiency. One is the output efficiency of photovoltaic array. The other is the efficiency of photovoltaic inverter.MPPT method is the significant way to improve the efficiency. This paper analyzes CVT method and ordinary MPPT method. Then this paper proposes an improved MPPT method (dP-P&O method) against the misjudging phenomenon when using the traditional P&O method. This method could stably and efficiently track the maximum power point of array. Meanwhile, when the irradiation intensity changes drastically, this method could avoid the misjudging phenomenon, keep the system stable and ensure the system a good dynamic characteristic.The high-frequency-link inverter replaces traditional inverter in PV generation system and it is an important method to increase the system efficiency. This paper focuses on the research of current-source full-bridge high-frequency-link inverter, devises the main circuit and control circuit and makes a prototype with capacity of 200VA. The experimental result shows that the output characteristic is good and the output voltage can be stabilized at 220V.This paper analyzes the loss of high-frequency-link inverter, deduces the calculation equations for loss of each component and calculates different loss when the output capacity differs. The analysis towards loss illustrates that the key to improve the efficiency is to reduce the peak and root-mean-square current as well as the winding and MOSFET's turn-on resistance when the output capacity keeps the same.