Impact of large-scale rooftop solar PV integration: An algorithm for hydrothermal-solar scheduling (HTSS)

Abstract

Hydrothermal scheduling is a standard problem in the operation of power systems. With the integration of renewable resources, like solar and/or wind to the existing hydro-thermal system, there is a need for a dedicated approach for long-term generation scheduling of the integrated system. Long-term generation scheduling of hydro-thermal-solar systems at the grid level has not been reported so far. This paper discusses a Hydrothermal-Solar Scheduling (HTSS) algorithm for the same. The algorithm is a two-stage formulation using dynamic programming and linear programming techniques. This generic methodology can be used for assessing the impact of large-scale rooftop solar-PV integration with a hydrothermal system, in terms of the electricity energy-mix, generation schedules and the annual generation-costs of the concerned system. It has been illustrated by application to the problem of integration of a large-scale rooftop solar photovoltaic scenario with the existing Mumbai sub-system.The results show a significantly higher annual generation-cost saving, achieved by integrating the large-scale rooftop solar photovoltaic scenario via the proposed HTSS algorithm. The benefits, however, reduce with increasing penetrations of solar in the electricity energy-mix. The annual generation-cost savings have also been used for estimating the upper cap on feed-in tariffs for solar generation, and the financial viability indicators for the large-scale rooftop solar photovoltaic scenario; the corresponding internal rate of return is found to decline from 18.4% to 16.6% as the share of solar-PV in the electricity energy-mix of Mumbai increases from 2.8% to 13.9%.