Impact of variable solar radiation on power flow for Dish-Stirling systems

To achieve sustainable development for power generation and avoid the pollution in the generation process, using renewable resources to generate power is becoming a common trend. The energy system analyzed in this project, solar Dish-Stirling system, is one of the most efficient energy systems in the world. This paper is aiming to find out the impact of the variability of solar radiation in the system’s power flow. The Dish-Stirling system consists of three main components: the concentrator, the receiver and the power conversion unit (PCU). PCU has three parts: the Stirling engine, the induction generator and the controlling systems. From the modelling results, of this thesis, the system output and solar-to-electric efficiency can be controlled by the working gas pressure. Therefore, the system can be simply controlled by the pressure control system. The variation of the solar irradiance was modeled and connected to system output after modeling the system and assuming the series of system variables as constant. By putting the system into a simple network, the relationship between the output power and the input radiation was revealed. Plot of the results of simulation were to help have a better understanding of the impact of solar variation on the system. To have a better understanding of the system efficiency level and its relation with the solar radiation, a comparison between the solar Dish-Stirling system anda PV module was made. The PV module was put into the proposed system also with all parameters constant. For further analysis of impact of the Dish-Stirling system in a larger network, simulation with Dish-Stirling solar farm connected to a 12 bus network with variable radiation was performed. The impact on the PCC, loads and generators can be detected by varying the solar radiation from the lowest level (200W/m2) to the highest level (1000W/m2). From the results of the simulation, the output power of solar Dish-Stirling system is on an increasing trend with the increase of the solar radiation level. Compare the trend with the PV system, the Dish-Stirling system has higher solar to electric efficiency and the output is more stable. When analysing the system in larger network, the simulation shows that generator voltage increases with the increase of the radiation. Nearer load to the Dish-Stirling solar farm has bigger effect due to the variation of the solar radiation. Therefore, more protection devices need to be provided to the nearby loads to ensure the safety of the network. To meet the load demand, the spinning reserve of the network should be large enough to handle the situation without the Dish-Stirling solar farm. In addition, voltage control devices are necessary for the load buses and PCC bus to keep the system voltage in a stable range