Abstract: A pressurized fluidized bed combustion combined cycle power plant has a gas turbine unit of single spindle type in which a turbine, driven by combustion gas from burning of coal in a pressurized fluidized bed combustion boiler, drives an electrical generator at constant speed and drives a compressor supplying compressed combustion air to the boiler. To permit partial load operation, a control arrangement is provided to effect, in dependence upon an operating load of the boiler, control of at least one of the flow rate of the combustion air into the boiler, and the operating pressure in the combustion chamber of the boiler. The control arrangement may be, for example, a valve controlling a by-pass flow of the combustion air and/or inlet guide vanes of the compressor.