Patent Publication Number: US-2013236290-A1

Title: System and method for turbomachine monitoring

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to turbomachines and, more particularly, to systems and methods for turbomachine monitoring. 
     Turbomachines generally include a compressor that compresses inlet air, a combustor in which the compressed inlet air is mixed with fuel and combusted and a turbine in which products of the combustion are expanded in power generation operations. Each turbomachine part may further include components that have variable geometries whereby the shape, size and/or orientation of the components are changeable in accordance with turbomachine operations. For example, the compressor may include a variable stator vane (VSV) system that controls an amount air that is permitted to flow through the compressor. In the VSV system, compressor vane angles are set by an actuator that is commanded by control logic. 
     There are many methods to detect a failure in the actuator. For example, the control logic may be configured to detect a difference between an actuator position demand, which sets a compressor vane angle, and the actuator position feedback, which indicates the actual compressor vane angle. This type of fault logic does not address failures in the VSV hardware, such as a mechanical disconnect between the VSV actuator and the VSV lever arms. Thus, it is possible that a detected difference between the actuator position demand and the actuator position feedback may not be reflective of the actual compressor vane angle at the given time. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a system for monitoring a turbomachine is provided. The system includes a turbomachine component having a variable geometry, a first sensor disposed to sense a condition of the turbomachine component, a second sensor disposed to sense an operational condition of the turbomachine, the operational condition being associated with an operation of the turbomachine component and a controller operably coupled to the first and second sensors, the controller being configured to execute a turbomachine process in accordance with a result of sensing by the second sensor with respect to the operational condition regardless of whether the first sensor detects the condition. 
     According to another aspect of the invention, a turbomachine is provided and includes a compressor configured to compress inlet air, the compressor including inlet vanes having a variable geometry, which are disposed to permit airflow into the compressor in accordance with a current geometry of the inlet vanes, a first sensor disposed to sense a condition of the inlet vanes, a second sensor disposed to sense an operational condition of the turbomachine, the operational condition being associated with an operation of the inlet vanes and a controller operably coupled to the first and second sensors, the controller being configured to execute a turbomachine process in an event that the first sensor detects the condition and in accordance with a result of sensing by the second sensor with respect to the operational condition. 
     According to yet another aspect of the invention, a method for monitoring a turbomachine is provided and includes setting a turbomachine component having a variable geometry to assume a current geometry, disposing a first sensor to sense a condition of the turbomachine component with respect to an assumption of the current geometry, disposing a second sensor to sense an operational condition of the turbomachine, the operational condition being associated with an operation of the turbomachine component and executing a turbomachine process by a controller in an event that the first sensor detects the condition and in accordance with a result of sensing by the second sensor with respect to the operational condition. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. 
       The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a graphical depiction of a compressor operating line generated by a Variable Stator Vane (VSV) system feedback failure; 
         FIG. 2  is a schematic diagram of a turbomachine; 
         FIG. 3  is a schematic diagram of a turbomachine component having a variable geometry; and 
         FIG. 4  is a schematic diagram of a controller operably coupled to the turbomachine of  FIG. 2 . 
       The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , an exemplary gas turbine engine has a variable stator vane (VSV) system in a high pressure compressor (HPC). The angular position of the compressor vanes is driven by a hydraulic actuation system having a position feedback integrated with the hydraulic actuator. A controller contains logic that positions the VSV actuator position demand and also compares the position demand with the position feedback. If the difference between the position demand and feedback is greater than a threshold and greater than a time threshold, a fault will be generated and the controller will respond accordingly. The control logic does not, however, generally protect against any failure in the VSV positioning system that occurs beyond the actuation system feedback. So even though the actuator position matches the demanded position, the HPC might be at risk for a surge since the stator vane angles may still be unknown. 
     Such a VSV feedback failure can produce significant noise, as shown in  FIG. 1 , in which vane angle excursions are found to be outside a typical range for short time periods that are insufficient in terms of the persistence of the vane angle excursions to cause the controller to respond. In some cases, such situations may be identified by data from certain sensors throughout the corresponding turbomachine but if not corrected could lead to full vane angle closure and damages. Thus, control logic is provided and described below that detects or monitors certain variable geometry behavior and its effect on a corresponding turbomachine so that appropriate responses (i.e., adjustments or forced shutdowns) can be timely executed. 
     With reference to  FIGS. 2-4 , a system for monitoring a turbomachine  10  is provided. The turbomachine  10  includes a compressor  11 , such as a high pressure compressor, which is configured to compress inlet air, a combustor  12  in which the compressed inlet air is combusted along with fuel and a turbine  13  in which products of the combustion are expanded in power generation operations. The turbine  13  is disposed on a rotatable shaft  14 , which drives the compressor  11  and a generator  15 . The generator  15  converts the mechanical energy of the turbine  13  into electrical power that is output from the turbomachine  10 . 
     The compressor  11  includes a turbomachine component, such as a variable stator vane (VSV) system  110 . The VSV system  110  includes compressor inlet vanes  111 , which have a variable geometry and are disposed to occupy a predefined current geometry. That is, the compressor inlet vanes  111  may occupy variable vane angles and are able to be positioned at a predefined current vane angle at which the compressor inlet vanes  111  moderate an amount of air that is permitted to flow through the compressor  11 . The VSV system  110  further includes an actuation system  112 , which is configured to control the compressor inlet vanes  111  to assume the predefined vane angle, and a system controller  113  operably disposed to respond, adjust or otherwise take corrective action in an event the compressor inlet vanes  111  fail to assume the predefined vane angle by a predefined threshold for more than a predefined time period. The system controller  113  may include a VSV system sensor  1130 , which is disposed to sense a condition, such as an abnormal condition, of the VSV system  110 . 
     Although the turbomachine component is described above as being the VSV system  110 , it is to be understood that the turbomachine component can be any component of the turbomachine  10  that has a variable geometry. The description of the VSV system  110  is exemplary and is relied upon herein for clarity and brevity. 
     The turbomachine  10  further includes a first sensor, which could be the VSV system sensor  1130  of the system controller  113  of the VSV system  110 , and which is disposed to sense the condition (e.g., the above-noted abnormal condition) of the turbomachine component, one or more second sensors  20 - 24  and a controller  30 . The one or more second sensors  20 - 24  may be disposed to sense an operational condition of the turbomachine, which may be associated with an operation of the turbomachine component (i.e., the VSV system  110 ). The controller  30  is operably coupled to the first sensor  1130  and to the one or more second sensors  20 - 24  and is configured to respond, adjust or, in certain cases, execute a turbomachine process in accordance with a result of sensing by any one or more of the second sensors  20 - 24 . In an exemplary case, the controller  30  is configured to execute a corrective process of the turbomachine  10  in an event that any one or more of the second sensors  20 - 24  detects an anomaly associated with the operational condition regardless of whether the first sensor  1130  detects the above-noted abnormal condition. More specifically, the controller  30  is configured to execute a corrective process of the turbomachine  10  in an event that the first sensor  1130  detects the abnormal condition and any of the one or more second sensors  20 - 24  detects an anomaly associated with the operational condition. 
     As shown in  FIG. 4 , the controller  30  may be further coupled to the turbomachine  10  and to an alarm system  31 . As such, in accordance with embodiments, the corrective process may include at least one or more of the controller  30  generally responding to the situation, adjusting an operation of the turbomachine  10 , executing a process of shutting the turbomachine  10  down and causing the alarm system  31  to issue an alarm or a warning signal to an operator. 
     In accordance with embodiments, the above-noted abnormal condition sensed by the first sensor  1130  may be determined to be in effect when the compressor inlet vanes  111  are determined to have failed to assume the predefined vane angle by the predefined threshold for less than the predefined time. As noted above, this situation would have previously been regarded as mere noise and would not have normally been identified as problematic. In contrast, the abnormal condition is now seen as being potentially problematic at least for the purposes of the embodiments described herein. 
     The operational condition sensed by the second sensors  20 - 24  may be at least one or more of an exhaust gas temperature of the turbomachine  10  (sensed by second sensor [ 1 ]  20 ), a core speed of the turbomachine  10  (sensed by second sensor 
       21 ), a generator output of the turbomachine  10  (sensed by second sensor [ 3 ]  22 ), a high pressure compressor discharge pressure of the turbomachine  10  (sensed by second sensor [ 4 ]  23 ) and a pressure in an inlet of a high pressure compressor of the turbomachine  10  (sensed by second sensor [ 5 ]  24 ). In each case, the operational condition is related to and/or associated with the operation of the turbomachine component (e.g., the VSV system  110 ). 
     The anomaly associated with the operational condition may be identified as at least one or more of the sensed exhaust gas temperature of the turbomachine  10  being increased or decreased, the sensed core speed of the turbomachine  10  being increased or decreased, the sensed generator output of the turbomachine  10  being increased or decreased, the sensed high pressure compressor discharge pressure of the turbomachine  10  being increased or decreased and the sensed pressure in the inlet of the high pressure compressor of the turbomachine  10  being increased or decreased. 
     In an exemplary case, the turbomachine component is the VSV system  110  and the compressor inlet vanes  111  are operating normally but a mechanical fault, which is not sensed by any sensing device, is presently occurring. In this case, the first sensor  1130  may not register or identify that an abnormal condition is in effect. At the same time, the second sensor [ 1 ]  20  may sense a substantially increased exhaust gas temperature and the second sensor [ 2 ]  21  may sense a substantially increased core speed as a result of the mechanical fault. In either of these situations, the substantially increased exhaust gas temperature or the substantially increased core speed would be identifiable as an anomalous operational condition. Logic in the controller  20  could then cause the controller  30  to execute the corrective process of the turbomachine  10  regardless of whether the first sensor  1130  detects the abnormal condition or not. 
     In a further exemplary case, the turbomachine component is the VSV system  110  and the compressor inlet vanes  111  are closed by a substantially greater degree than the commanded vane angle for less than the predefined period of time as sensed by the first sensor  1130 . This case is indicative of the abnormal condition being in effect. In addition, the second sensor [ 1 ]  20  may sense a substantially increased exhaust gas temperature and the second sensor [ 2 ]  21  may sense a substantially increased core speed. In either of these situations, the substantially increased exhaust gas temperature or the substantially increased core speed would be identifiable as an anomalous operational condition that when coupled with the indication of the abnormal condition being in effect may result in the logic in the controller  30  causing the controller  30  to execute the corrective process of the turbomachine  10 . Stated generally, if any of the readings of the second sensor  20 - 24  are particularly high or low, such readings may be indicative of the anomalous operational condition and a corresponding malfunction in the turbomachine component that may previously have appeared to be mere noise. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.