Abstract: Exploration of renewable energy is a basic state policy in China. The intermittency of renewable energy leads to its power output fluctuation，which would bring a certain impact on the safety of power grid operation and hinder the grid connection of partial renewable energy. In order to increase the to-grid rate of power generated by renewable energy，it is necessary to advance the flexibility of load outputted from traditional coal-fired power plants. Studying the load regulation range of coal-fired units，it was found that hot water storage technology，electric boiler heat storage technology and high back pressure transformation technology could be applied in flexible regulation of combined heat and power plant. The coupling technology for coal-fired units and solar system could improve the operation flexibility of the coupling system. Taking high-temperature thermal energy storage technology ，storage medium can be heated by excessive steam from condensing units during bottom load periods and release the heat during peak load periods，which realizes the wide-range flexibility regulation of units. Comparing the features of five flexibility regulation technologies，it is considered that hightemperature molten salt heat storage technology is one of the development directions of flexibility regulation for coal-fired power plants.

Key words: coal-fired power plant, renewable energy, solar power, peak regulation, heat storage, high-temperature molten salt, CCHP, thermo-electric decoupling, high back-pressure transformation