The transformation of energy production to renewable energy is the only way to achieve the dual-carbon goal. At present

the lack of peak shaving capacity and flexibility of coal-fired units hinders the large-scale consumption of renewable energy. In this paper

taking a 600 MW coal-fired unit as the research object

eight schemes for peak shaving system aided by molten salt heat storage are proposed

and the peak shaving capacity and thermal performance of each scheme are compared and analyzed through simulation calculation. The results show that

the peak shaving system can improve the flexibility of coal-fired unit

effectively regulate the output

and greatly expand the operating range. Heating by electricity causes a large amount of exergy loss

while extracted exhaust of intermediate pressure cylinder causes a small amount of exergy loss. The maximum peak shaving capacity can be obtained by the scheme of heating the molten salt directly by electric energy output by generator when charging

and heating the bypass feedwater by high-temperature molten salt when discharging

whose peak shaving depth can reach 17.83%. Moreover

the highest system efficiency and economy can be obtained by the scheme of heating the molten salt with extracted exhaust of intermediate-pressure cylinder when charging

and heating the bypass feedwater with high-temperature molten salt when discharging

of which the system thermal efficiency and exergy efficiency are 40.95% and 40.29% respectively

and the coal consumption rate is 350.01 g/(k W·h).