Since the beginning of the 21st century, under the guidance of relevant environmental protection targets of the EU and relevant Portuguese supporting laws and regulations, the renewable energy has developed rapidly in Portugal, and the Portuguese power generation system has developed steadily towards the carbon-free hybrid power generation system. In recent years, the Portuguese power grid has experienced three times of 100% renewable energy to support the continuous operation of the national power load for several days. It appeared twice in 2016, which was the continuous network load of renewable energy supply for 96 consecutive hours in February 2016. In May 2016, it was 107 hours of continuous renewable energy supply nationwide. The most recent one occurred on March 9, 2018, with 63 hours of continuous energy supply to the Portuguese national load. The successful accommodation of large-scale renewable energy in power systems is a systematic project. It relies on energy planning, national transmission network planning, operation and control technologies, and market mechanisms to support all renewable energy across the country.