Thermal efficiency diagnostic method and apparatus of a combined power generation plant

A thermal efficiency diagnostic method of a combined power generation plant, comprising the steps of:

• using measurement values of parameters relative to an energy input and an output with regard to respective equipments of a combined power generation plant including a gas turbine facility and a steam turbine facility, etc., and recording a design value of each equipment;
• using measurement data having high accuracy as standard parameter, which is rigid through optimum state estimation of a heat balance;
• using measurement data, which affect diagnostic results to a large degree and which are difficult to be measured with high accuracy, as key parameters;
• using a number of calculation data of the heat balance as reference parameters, which are compared with their reference values in order to calculate the entire probability of the heat balance;
• conducting optimum state estimation of the heat balance by adjusting the key parameters so as to be consistent with the standard parameters and so that each deviation of reference parameters becomes minimum as a whole and the probability becomes maximum in the plant;
• comparing the heat balance thus determined with the heat balance based on a design value;
• analyzing degree of contribution of performance of each respective equipment to thermal efficiency;
• and
• specifying an equipment which causes heat efficiency deterioration in accordance with the degree of contribution.