Performance evaluation of a stand-alone solar dish Stirling system for power generation suitable for off-grid rural electrification

The development of green power generation such as solar systems that have become a great interest for several countries especially for Tunisia as it presents a significant solar potential. For this purpose, this research has investigated the feasibility and the performance of standalone solar dish/Stirling micro generation plant for rural electrification. The considered hybrid system includes solar dish/Stirling engine, permanent magnet synchronous generator and a storage battery. To start with, thermal modeling and simulation have been carried out using Matlab® for the solar-driven Stirling heat engine system composed of an Alpha Stirling engine, a solar collector and a receiver, in which the radiation, convection, conduction and radiation heat loss have been taken into consideration for the selected design. For numerical validation of the receiver's thermal model, simulation results were compared with experimental measurements reported for the EURODISH system with a reasonable degree of agreement. Second, the generated torque driving the generator has been estimated by the Adiabatic model of URIELI based on the classical fourth-order Runge-Kutta. In order for an autonomous control, the dish generator is connected to the load via power electronic converters where the bidirectional power flow is possible by the use of two voltage source converters in a back-to-back configuration. They are referred to as Stirling/generator side converter and load side inverter, both are oriented control by space vector pulse width modulation. In this context, the Stirling side converter is used to adjust the synchronous generator while the inverter controls the power flow between the direct current bus and the alternative side. Detailed tests of the proposed hybrid configuration was implemented in Matlab/Simulink software, by taking as a case study a measured load profile for a rural house and solar radiation data at the target area. The analysis of simulation results has shown that solar dish Stirling/synchronous generator system achieves the objectives of system autonomy and power supply stability. The effectiveness of the management strategy was also proved. It has been obtained that the variable speed Stirling/generator system is capable to feed an uncontrollable load under variations of climatic conditions during hot, moderate and cold seasons, in remote areas in Tunisia.