| As an important application of photovoltaic(PV)systems,PV pump systems(PVPS)need not fuel consumption,have the advantages of easy installation,low maintenance,unattended,low operating costs,clean and pollution-free,and are considered to be the most likely choice to meet the crop irrigation and drinking water in power shortage area.This master thesis focuses on the experimental investigation of two types of small PVPS,which is designed to find out their feasibility and promotional value in the weather conditions of Zhengzhou city.The main contributions are as follows:(1)Based on the historical data of irradiance and temperature,this thesis found that the solar energy resource in Zhengzhou is abundant,and the weather condition is good for developing PV systems.Moreover,the basic structure and classification of PVPS,the maximum power point tracking(MPPT)techniques and the motor control strategy are also briefly discussed in Section 1.(2)According to the application scenarios of fixed irrigation and portable mobile garden irrigation,Section 2 selected and elaborated two types of small DC motor pump: 3DS-4-003 0-100 three-phase positive displacement piston pump and ZQB3X8-24 two-phase centrifuge pump,which are suitable for the agriculture,rural areas and farmers of Zhengzhou.(3)In order to facilitate the outdoor test and travel exhibition of small PVPS,Section 3 designed and constructed a mobile testbed,which is largely based on the boundary dimension of 3DS-4-0030-100 PVPS.The testbed has the following features: the oblique angle of PV array is continuous and adjustable in the range of 18~51°,the cylindrical water tank is suitable for most small motor pump,the bottom installs four universal wheels,all components are connected by bolts which make the testbed simple to produce,assemble and dismount.(4)Section 4 developed a PV array controller with universal input and flexible output voltage using double-switch Buck-Boost converter and STM32F103RET6 microcontroller.The hardware of PV array controller mainly includes the minimum system circuit of micro controller,the power supply circuit,the double-switch Buck-Boost converter and the signal collection circuit,while the software adjusts the duty cycle of PWM to regulate DC/DC converter and uses combined algorithm for MPPT of PV array.(5)Under the winter-weather conditions of zhengzhou,the system performance of two different PVPS,the PWM and MPPT performance of the PV array controller designed in this thesis are tested.The experimental results showed that both the 3DS-4-0030-100 and ZQB 3X8-24 PVPS can work more than 6 hours per day under the conditions of irradiance less than 550 W/m2,cell temperature less than 20℃ and the power capacity of PV array less than 140 W.These suggest that both the two PVPS are suitable for the fixed irrigation and portable mobile garden irrigation of Zhengzhou,respectively.Under different load patterns,the PV array controller designed in this thesis performs fairly well in tracking the maximum power points of PV array,which is manifested by fast,accurate and robust.Together,these experimental results suggest that Zhengzhou has good conditions for the application of small PVPS,and thus worth popularizing. |
