Modelling of a Large-Scale Standalone Solar Powered Irrigation System Employing Incremental Conductance Mppt Algorithm Case Study: 

Rural Area and Hillside Areas of Rwanda

Emile Niringiyimana

2016-2019

Master in Renewable Energy and Clean Power

ABSTRACT

Different technologies have been invented to improve the irrigation system and agriculture production for food security which is one of the primary and basic need of human being. Approximately, 80% people around the world mainly depend on agriculture, directly or indirectly. However, the irrigation by water pumps can’t be maintained regularly due to frequent power shortages, no access to national grid lines in rural areas, hillside irrigation and fuels high cost to run pumps. Those issues cause the unstable food security and barrier in development of the country. This thesis mainly developed a 30kW solar photovoltaic powered irrigation system in Simulink with incremental conductance based MPPT functions to keep the system’s stability and efficiency. The system dynamic modelling was done using Simulink; PV array of 100 modules, a 5-kHz DC-DC converter rises the array system’s voltage from 273 Vdc to a suitable voltage of 500 Vdc that can be converted to AC, a 3-level 3-phase Voltage Source Converter (VSC) and a capacitor bank that filters harmonics produced in VSC was used. A VSC converts 500 Vdc link from VSC to 260 Vac that is a supply to the pumping system unity and keeps unity power factor. When a DC-DC conversion is performed in the VSC, harmonics are generated and these harmonics are filtered by a capacitor bank of 10 kvar. The pumping system unity can provide a total quantity of 1237.5 m3 /day of water to an 18.5 Ha corn irrigation area for 3 hours. The system includes backup batteries of 110V nominal voltage which is charged during the sunny day and can deliver a voltage to the pumping unity during cloudy days and whenever the power is needed when the solar is not enough or unavailable. This helps maintaining the system performance. The outcomes of the simulation help to observe the behavior of the real photovoltaic system. Firstly, the project started by developing a photovoltaic model, then combine the MPPT device with an incremental algorithm with a DC-DC converter that verifies the accuracy of the MPPT controller. A DC-AC inverter connected to the outputs of the DC-DC converter with an electric motor pump connected to its outputs as the main load in the system. The results obtained from simulations are: PV module output voltage, DC-DC converter output voltage with the duty cycle, AC voltage and current, array output power, stator currents, pump torque, load operating speed and irrigation parameters were calculated (pump flow, pump efficiency and total irrigation area).

KEYWORDS: SPV system, MPPT, Incremental conductance algorithm, DC-DC boost converter, level 3-phase VSC