Gas Turbine Performance Test
Introduction
The performance analysis of the new generation of gas turbines arecomplex and presents new problems， which have to be addressed. The newunits operate at very high turbine firing temperatures.Thus， variation in this firing temperature significantly affects the performance and life of the com-ponents in the hot section of the turbine. The compressor pressure ratio ishigh which leads to a very narrow operationmargin， thus making the tur-bine very susceptible to compressor fouling. The turbines are also very sensi-tive to backpressure exerted on them when used in combined cycle or cogeneration duty. The pressure drop through the air filter also results in major deterioration of the performance of the turbine.
If a life cycle analysis were conducted the new costs of a plant are about 7-10%ofthelifecyclecosts.Maintenancecostsareapproximately1 -20%of the life cycle costs. Operating costs， which essentially consist of energycosts，makeuptheremainder，between70-80% ofthelifecyclecosts，ofanymajor power plant. Thus， performance evaluation ofthe turbine is one ofthe most important parameter in the operation of a plant.
Total performance monitoring on or off line is important for the plant engineers to achieve their goals of:
1.
Maintaining high availability of their machinery.
2.
Minimize degradation and maintain operation near design efficiencies.
3. Diagnose
problems， and avoid operating in regions， which could lead to serious malfunctions.
4. Extend time between inspections and overhauls.
. Reduce life cycle costs.
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To determine the deterioration in component performance and efficiency， the values must be corrected to a reference plane. These corrected measure-ments will be referenced to different reference planes depending upon thepoint， which is being investigated. Corrected values can further be adjusted to a transposed design value to properly evaluate the deterioration of any given component. Transposed data points are very dependent on the char-acteristics of the components performance curves. To determine the charac-teristics of thesecurves， raw data points must be corrected and then plotted against representative nondimensional parameters. It is for this reason that we must evaluate the turbine train while its characteristics have not been altered due to component deterioration. If component data were availablefrom the manufacturer， the task would be greatly reduced.
Performance .odes
Performance analysis is not only extremely important in determining overall performance of the cycle but in also determining life cycle considera-tions of various critical hot section components.
In this chapter， a detailed technique with all the major equations govern-ing a Gas Turbine Power Plant are presented based on the various ASME Test Codes. The following five ASME Test Codes govern the test of a Gas Turbine Power Plant:
1. ASME，
Performance Test Code on Overall Plant Performance， ASMEPTC 461996， American Society of Mechanical Engineers 1996
2. ASME，
Performance Test Code on Test Uncertainty: Instruments andApparatus PTC 19.1， 1988
3. ASME，
Performance Test Code on Gas Turbines， ASME PTC 22 1997， American Society of Mechanical Engineers 1997
TheASME， Performance Test Code on OverallPlant Performance，ASME PTC46， was designed to determine the performance of the entire heat cycle as an integrated system. This code provides explicit procedures to determination of power plant thermal performance and electrical output.
The ASME， Performance Test Code on Test Uncertainty: Instruments and Apparatus PTC 19.1 specifies procedures for evaluation of uncertainties in individual testmeasurements， arising form both random errors and
Table 20-1 Instrumentation Accuracy
Measurement Bias Uncertainty
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