Real-time optimization of a solar-natural gas hybrid power plant to enhance solar power utilization

A dynamic model of a natural gas/solar hybrid system was developed using heat integration and smart flow control. Natural gas was used as a supplemental fuel, which enhanced the reliability of the system and increased the power block cycle efficiency through the use of higher temperatures. In this work, the synergy of the two energy sources (solar and natural gas) was exploited with real-time optimization (RTO). A quadratic programming-based optimizer was used to redirect heat to the steam generator or to boiler feedwater pre-heating as the optimizer dictates. During low solar conditions, the RTO directs the solar heat to the lower temperature heat sink (the boiler feedwater preheater) to make better use of the solar heat. During high solar conditions, the solar heat flows through the steam generator (the high-temperature heat sink) and to the boiler feedwater pre-heater in series. The optimization is more effective at low irradiance conditions (morning, evening, winter, cloud cover etc.) because it is able to identify conditions that maximize solar utilization. Yearly results demonstrate the model observed an improvement of 10% in terms of solar to electric efficiency (STE) and 10.7% in solar fraction. Optimization increased the solar share and maximized greener energy.