Method for low load operation of a power plant with a once-through boiler

A method for low load operation of a power plant having a once-through boiler and at least one high pressure turbine, the once-through boiler having a water supply and an economizer, an evaporator and a superheater, the at least one high-pressure turbine comprising a control valve, the method comprising:

• providing at least one parameter indicative of stable operation of the once-through boiler in once-through operation, the at least one parameter obtained from a temperature and/or pressure measurement system and/or from a software model;
• and
• on the basis of the at least one parameter, (i) adjusting the control valve to regulate the pressure within the economizer and the evaporator and (ii) adjusting the temperature of the water supplied to the economizer,
• wherein low load is defined by a number of critical load values, and a number of partially open positions of the control valve are provided, each position being associated with a respective one of the number of critical load values, and when the load falls below a given load value of the number of critical load values, the method comprises adjusting the control valve to the partially open position associated with said given load value.