Systems for stabilizing gas turbine engine output during grid events

Abstract

A power generation system coupled to a power grid, the power generation system including a controller configured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected. The power generation system includes a gas turbine engine, a heat recovery steam generator, and an exhaust gas recirculation line. A compressor of the gas turbine engine includes an inlet oriented to receive an air flow, and a recirculation inlet. A turbine of the gas turbine engine is configured to discharge an exhaust gas stream therefrom. The heat recovery steam generator is configured to extract heat from the exhaust gas stream and discharge an exhaust gas recirculation stream therefrom. The exhaust gas recirculation line is configured to channel the exhaust gas recirculation stream towards the compressor. The exhaust gas recirculation stream includes at least one recirculation cooler and a recirculation blower.

Description

SYSTEMS FOR STABILIZING GAS TURBINE ENGINE OUTPUT DURING GRID EVENTSBACKGROUND

[0001] The present disclosure relates generally to gas turbine engines and, more specifically, to systems that use recirculated exhaust gases to mitigate compressor flow disruption and to stabilize gas turbine engine output during grid events.

[0002] Gas turbine engines are widely used in industrial and power generation operations, and generally include a compressor, a turbine, and a combustion system. The combustion system supplies hot gases to drive the turbine, which in turn drives the compressor. The compressor compresses air for combustion in the combustion system that is used to produce usable power output for a power grid. In at least some gas turbine engines, there are instances during operation when the flow through the compressor is disrupted due to a grid event of the power grid, such as a change in grid frequency. For example, a grid event can cause a compressor stall, resulting in a partial disruption of flow, or a compressor surge, resulting in a complete disruption of flow. Depending on the severity, flow disruptions can induce a reversal of the flow through the compressor, which can destabilize the output from the gas turbine engine during the grid event. Similarly, a grid event can cause flow disruption and a change to the fuel to air ratio in the combustion system, which may lead to combustion instability and potential loss of flame or emergency shut down of the gas turbine engine.

[0003] At least some known gas turbine engines may include modifications to the compressor and / or the turbine to minimize flow disruption during grid events. Such modifications may attempt to increase the margin between the operating pressure ratio of the gas turbine engine and the maximum pressure ratio before a compressor surge may occur, known in the art as the increasing surge margin. However, due to the load limitations of the grid, known modifications may not adequately improve the surge margin to a level needed to stabilize the power output of the gas turbine engine. Accordingly, there exists a need for systems that use recirculated exhaust gases to mitigate compressor flow disruption and to stabilize gas turbine engine output during grid events.BRIEF DESCRIPTION

[0004] In one aspect, a power generation system coupled to a power grid is provided. A gas turbine engine includes a compressor, a combustion system, and a turbine. The compressor includes an inlet and a recirculation inlet, wherein the inlet is oriented to receive an air flow. The turbine is configured to discharge an exhaust gas stream therefrom. A heat recovery steam generator is configured to extract heat from the exhaust gas stream and discharge an exhaust gas recirculation stream therefrom. An exhaust gas recirculation line configured to channel the exhaust gas recirculation stream towards the compressor. The exhaust gas recirculation line includes at least one recirculation cooler configured to cool the exhaust gas recirculation stream. The exhaust gas recirculation line further includes a recirculation blower configured to receive a cooled exhaust stream from the at least one recirculation cooler, and discharge a second exhaust stream towards the compressor. A controller is configured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected.

[0005] In another aspect, a power generation system coupled to a power grid is provided. A gas turbine engine includes a compressor, a combustion system, and a turbine. The compressor includes an inlet and a recirculation inlet, wherein the inlet is oriented to receive an air flow. The turbine is configured to discharge an exhaust gas stream therefrom. A heat recovery steam generator is configured to extract heat from the exhaust gas stream and discharge an exhaust gas recirculation stream therefrom. An exhaust gas recirculation line configured to channel the exhaust gas recirculation stream towards the compressor. The exhaust gas recirculation line includes at least one recirculation cooler configured to cool the exhaust gas recirculation stream. The exhaust gas recirculation line further includes a recirculation blower configured to receive a cooled exhaust stream from the at least one recirculation cooler, and discharge a second exhaust stream towards the compressor. A recirculation stack is configured to receive the second exhaust stream from the recirculation blower, discharge a first portion of the second exhaust stream towards the compressor recirculation inlet, and discharge a second portion of the second exhaust stream to atmosphere. A controller is configured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected.

[0006] In yet another aspect, a controller is provided. The controller is coupled to one of a cooler, a blower, a recirculation stack, and a recirculation line to facilitate control of a power generation system coupled to a power grid.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a schematic illustration of an exemplary power generation system.

[0008] FIG. 2 is a schematic of an exemplary detection system for use with the power generation system of FIG. 1.

[0009] FIG. 3 is a schematic illustration of an exemplary power generation system including exhaust gas recirculation.

[0010] FIG. 4 is a schematic illustration of another exemplary power generation system including exhaust gas recirculation.

[0011] FIG. 5 is a schematic illustration of a further exemplary power generation system including exhaust gas recirculation.DETAIEED DESCRIPTION

[0012] The embodiments described herein relate to systems that use recirculated exhaust gases to mitigate compressor flow disruption and to stabilize gas turbine engine output during grid events. In the exemplary embodiment, the gas turbine engine powers a generator that is coupled to a power grid. During operation of the gas turbine engine, a grid event including a change in frequency of the power grid may occur. For example, a change in grid frequency that is outside of a predefined allowable frequency range may result in a mismatch of frequency between the generator and the power grid. However, in order to stabilize the frequency mismatch, a change in the power outputted by the gas turbine engine may be required. This may result in disruption of the flow through the compressor of the gas turbine engine.

[0013] The systems described herein use recirculated exhaust gases to facilitate controlling the inlet pressure of the compressor of the gas turbine engine during grid events, thus mitigating disruption to the flow through the compressor and minimizing the resulting destabilization of the gas turbine engine output. The advantages of the systems described herein include, at least: (i) minimizing the disruption of flow through the compressor of the gas turbine engine due to the inclusion of at least one of a recirculation cooler and / or a recirculation blower in an exhaust gas recirculation line; (ii) minimizing the disruption of flow through the compressor of the gas turbine engine due to the additional inclusion of a recirculation stack in the exhaust gas recirculation line; (iii) minimizing the disruption of flow through the compressor of the gas turbine engine due to the additional inclusion of a recirculation line in the exhaust gas recirculation line; and (iv) increasing the surge margin of the gas turbine engine due to a controller modulating at least one of an operating speed of the recirculation blower, a flow through the recirculation stack, and / or a flow through the recirculation line.

[0014] When introducing elements of various embodiments disclosed herein, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0015] Unless otherwise indicated, approximating language, such as “generally,” “substantially,” and “about,” as used herein indicates that the term so modified may apply to only an approximate degree, as would be recognized by one of ordinary skill in the art, rather than to an absolute or perfect degree. Accordingly, a value modified by a term or terms such as “about,” “approximately,” and “substantially” is not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Additionally, unless otherwise indicated, the terms “first,” “second,” etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to, for example, a “second” item does not require or preclude the existence of, for example, a “first” or lower-numbered item or a “third” or higher-numbered item.

[0016] FIG. 1 is a schematic illustration of an exemplary power generation system 100. In the exemplary embodiment, power generation system 100 includes a gasturbine engine assembly 102. Gas turbine engine assembly 102 includes a compressor 104, a combustor 106, and a turbine 108 coupled together in a serial flow relationship. In operation, combustor 106 receives air from compressor 104 and fuel from a fuel supply. Combustor 106 mixes the fuel and air to create a fuel-air mixture that is combusted to generate combustion gases. Combustion gases are channeled through turbine 108 and discharged from turbine 108 as a first exhaust gas stream 110. Compressor 104 includes a compressor inlet 116 and a compressor outlet 118. Turbine 108 includes a turbine inlet 120 and a turbine outlet 122.

[0017] In the exemplary embodiment, power generation system 100 also includes a heat recovery steam generator (HRSG) 112. HRSG 112 extracts heat from first exhaust gas stream 110 received by an inlet 114. In some embodiments, the extracted heat from first exhaust gas stream 110 may be discharged from HRSG 112 to be used by various other power generation system components not described herein, such as, but not limited to, a steam turbine and / or a carbon capture system. In the exemplary embodiment, gas turbine engine assembly 102 is coupled to a generator 124 that produces power using working fluids flowing through gas turbine engine assembly 102.

[0018] In the exemplary embodiment, power generation system 100 further includes a controller 126 used to dynamically adjust operation of power generation system 100. Controller 126 may facilitate stabilizing the output of power generation system 100 by improving the efficiency of compressor 104. For example, controller 126 may monitor the temperature of the air flowing into compressor 104 through compressor inlet 116. Lower temperatures generally decrease the power consumed by compressor 104, thus increasing the power supplied to generator 124. Additionally, controller 126 may facilitate stabilizing the output of power generation system 100 by improving the efficiency of turbine 108. For example, controller 126 may monitor the temperature of first exhaust gas stream 110 discharged from turbine 108 through turbine outlet 122. Lower temperatures generally increase the power supplied to generator 124 by turbine 108.

[0019] FIG. 2 is a schematic of an exemplary detection system 200 that may be used with a power generation system, such as power generation system 100 (shown in FIG. 1). In the exemplary embodiment, generator 124 is coupled to a power grid 202 to supply generated power to power grid 202. In the exemplary embodiment, generator 124 includes a first sensor 204, which may detect changes to power grid 202, such as a grid event that causes a change in the grid frequency outside of a predefined allowable frequency range. Controller 126 may facilitate stabilizing the output of power generation system 100 based on data received by detection system 200 from at least first sensor 204, such as, but not limited to, a change in the frequency of power grid 202 and / or an alternative signal generated by power generation system 100 or power grid 202 as a precursor to a grid event. For example, controller 126 may be in communication with first sensor 204 to detect the change in the frequency of power grid 202. First sensor 204 may measure the change in the frequency of power grid 202 to determine whether the change results in a grid frequency outside of the predefined allowable frequency range. In the exemplary embodiment, controller 126 includes a memory 206 and a processor 208. Controller 206 may detect the grid event based on comparisons to data stored in memory 206 (such as the predefined allowable frequency range), instructions stored in memory 206, and / or data analyzed by processor 208 (such as the measured change in grid frequency).

[0020] In the exemplary embodiment, compressor 104 includes a second sensor 210, which may detect an ambient temperature of the air (e.g., a temperature Tamb) received by compressor inlet 116 (shown in FIG. 1). Additionally, in the exemplary embodiment, turbine 108 includes a third sensor 212, which may detect a temperature of first exhaust gas stream 110 (e.g., a temperature Texhaust) discharged from turbine outlet 122 (shown in FIG. 1). Controller 126 may facilitate stabilizing the output of power generation system 100 (shown in FIG. 1) based on data received by data detection system 200 from at least second sensor 210 and / or third sensor 212. For example, controller 126 may be in communication with second sensor 210 to detect ambient temperature Tamb and / or with third sensor 212 to detect exhaust temperature Texhaust. Controller 126 may compare the detected temperatures Tamb and Texhaust based on data stored in memory 206, instructions stored in memory 206, and / or data analyzed by processor 208.

[0021] FIG. 3 is a schematic illustration of an exemplary power generation system 300 including exhaust gas recirculation. The embodiment illustrated in FIG. 3 is similar to the embodiment illustrated in FIG. 1, with the differences noted herein, and assuch, the same reference numbers are used in FIG. 3 as were used in FIG. 1. An exhaust gas recirculation stream 302 is drawn downstream from HRSG 112 and is channeled towards compressor 104. A first recirculation cooler 304, a recirculation blower 306, and a second recirculation cooler 308 are each coupled between HRSG 112 and compressor 104. Recirculation blower 306 is coupled between first recirculation cooler 304 and second recirculation cooler 308, with second recirculation cooler 308 being downstream from recirculation blower 306.

[0022] In the exemplary embodiment, first recirculation cooler 304 receives exhaust gas recirculation stream 302 and discharges a cooled flow 310 towards recirculation blower 306. Recirculation blower 306 receives cooled flow 310 and discharges a second flow 312 towards second recirculation cooler 308. Second recirculation cooler 308 receives second flow 312 and discharges a cooled second flow 314 towards compressor 104. Cooled second flow 314 is received at a compressor recirculation inlet 316 of compressor 104.

[0023] As described previously herein, controller 126 may detect a grid event of power grid 202 (shown in FIG. 2). In response to a grid event being detected, controller 126 may compare the ambient temperature Tamb and the exhaust temperature Texhaust, as described previously herein. In operating conditions wherein ambient temperature Tamb is less than exhaust temperature Texhaust, controller 126 may modulate the power output of power generation system 300 using exhaust gas recirculation stream 302. Specifically, controller 126 may cause recirculation blower 306 to modulate the flow of second flow 312 towards compressor 104. Thus, recirculation blower 306 may facilitate minimizing flow disruption through compressor 104.

[0024] In some embodiments, controller 126 may cause the operating speed of recirculation blower 306 to be increased to facilitate increasing the flow of second flow 312 and cooled second flow 314, thereby facilitating increasing the pressure proximate to compressor inlet 116. The increased pressure at compressor inlet 116 facilitates stabilizing the flow through compressor 104, thus facilitating increasing the surge margin of gas turbine assembly 102. In other embodiments, controller 126 may cause the operating speed of recirculation blower 306 to be further increased to facilitate reducing the flow of second flow 312 and cooled second flow 314, thereby facilitating increasing the pressure proximate to compressor inlet 116. The increased pressureproximate to compressor inlet 116 facilitates stabilizing the flow through compressor 104, thus facilitating increasing the surge margin of gas turbine assembly 102.

[0025] Additionally, controller 126 may cause first recirculation cooler 304 and / or second recirculation cooler 308 to modulate the power output by engine assembly 200. Specifically, controller 126 may modulate the flow of cooled flow 310 and / or cooled second flow 314 to facilitate increasing the output of compressor 104, based on a cooled (i.e., reduced) temperature of the flow being received by compressor 104, thus resulting in reduced power consumption. Additionally, controller 126 may modulate the flow of cooled flow 310 and / or cooled second flow 314 to facilitate increasing the output of turbine 108, based on a cooled (i.e., reduced) temperature of the flow received by turbine 108, thus resulting in increased power supply to generator 124 by turbine 108.

[0026] FIG. 4 is a schematic illustration of an exemplary power generation system 400 including exhaust gas recirculation. The embodiment illustrated in FIG. 4 is similar to the embodiments illustrated in FIGs. 1 and 3, with the differences noted herein, and as such, the same reference numbers are used in FIG. 4 as were used in FIGs. 1 and 3. In the exemplary embodiment, exhaust gas recirculation stream 302 is drawn downstream from HRSG 112 and channeled towards compressor 104. A recirculation stack 402 is coupled between HRSG 112 and compressor 104, with recirculation stack 402 being downstream from second recirculation cooler 308.

[0027] In response to a grid event of power grid 202 (shown in FIG. 2) being detected and the determination that temperature ambient Tamb is less than exhaust temperature Texhaust, controller 126 may modulate the power output by power generation system 400 using exhaust gas recirculation stream 302. Specifically, controller 126 may cause recirculation stack 402 to modulate the flow of cooled second flow 314 towards compressor 104. Recirculation stack 402 may be selectively opened by controller 126 to cause the flow of cooled second flow 314 towards compressor 104 to be reduced, thus facilitating reducing the temperature proximate to compressor inlet 116 to facilitate stabilizing the flow through compressor 104. In some embodiments, controller 126 may open the recirculation stack 402 in combination with modulating the operating speed of recirculation blower 306 (as discussed previously in reference to FIG. 3) to facilitate stabilizing the flow through compressor 104, thus facilitating increasing the surge margin of gas turbine assembly 102.

[0028] FIG. 5 is a schematic illustration of an exemplary power generation system 500 including exhaust gas recirculation. The embodiment illustrated in FIG. 5 is similar to the embodiments illustrated in FIGs. 1, 3, and 4, with the differences noted herein, and as such, the same reference numbers are used in FIG. 5 as were used in FIGs. 1, 3, and 4. In the exemplary embodiment, exhaust gas recirculation stream 302 is drawn downstream from HRSG 112 and channeled towards compressor 104. A recirculation line 502 is coupled between HRSG 112 and compressor 104, with an input end 504 of recirculation line 502 being coupled between second recirculation cooler 308 and recirculation stack 402, and an output end 506 of recirculation line 502 being coupled between first recirculation cooler 304 and recirculation blower 306. In some embodiments, input end 504 and / or output end 506 of recirculation line 502 may have an alternative position between HRSG 112 and compressor 104.

[0029] In response to a grid event of power grid 202 (shown in FIG. 2) being detected and a determination that ambient temperature Tamb is less than exhaust temperature Texhaust, controller 126 may modulate the power outputted by power generation system 500 using exhaust gas recirculation stream 302. Specifically, controller 126 may cause recirculation line 502 to modulate the flow of cooled second flow 314 towards compressor 104. Recirculation line 502 may be selectively opened at input end 504 by controller 126 to cause a portion 508 of cooled second flow 314 to be channeled through recirculation line 502 and away from compressor 104, thus facilitating reducing the temperature proximate to compressor inlet 116 to facilitate stabilizing the flow through compressor 104. In some embodiments, controller 126 may open the recirculation line 502 in combination with modulating the operating speed of recirculation blower 306 (as discussed previously herein in reference to FIG. 3) and / or opening the recirculation stack 402 (as discussed previously herein in reference to FIG. 4) to facilitate stabilizing the flow through compressor 104, thus facilitating increasing the surge margin of gas turbine assembly 102.

[0030] In response to a grid event of power grid 202 (shown in FIG. 2) being detected and a determination that ambient temperature Tamb is greater than exhaust temperature Texhaust, controller 126 may modulate the power output by power generation system 500 using exhaust gas recirculation stream 302. Specifically, controller 126 may cause recirculation line 502 and / or recirculation blower 306 to modulate the flow of second flow 312 and / or cooled second flow 314 towards compressor 104. The operating speed ofrecirculation blower 306 may be increased by controller 126 while recirculation line 502 is closed to facilitate increasing the pressure proximate to compressor inlet 116, thus facilitating stabilizing the flow through compressor 104 . In some embodiments, generally increasing the operating speed of recirculation blower 306 as such may result in about a 0.3% flow increase through gas turbine engine assembly 102 for every 1% flow increase in the exhaust gas recirculation flow. Additionally, the operating speed of recirculation blower 306 may be increased by controller 126 while recirculation line 502 is open to facilitate increasing the pressure proximate to compressor inlet 116, thus facilitating stabilizing the flow through compressor 104. Further, the operating speed of recirculation blower 306 may be increased by controller 126 while recirculation line 502 is moved from an open flow position to a closed flow position to facilitate increasing the pressure proximate to compressor inlet 116, thus facilitating stabilizing the flow through compressor 104 and facilitating increasing the surge margin of gas turbine assembly 102.

[0031] Exemplary systems for using recirculated exhaust gases to mitigate compressor flow disruption and to stabilize gas turbine engine output during grid events are described herein. The exemplary systems as described herein provide several advantages over conventional designs and processes, including, at least, minimizing the disruption of flow through the compressor of the gas turbine engine and increasing the surge margin of the gas turbine engine, while also minimizing disruption to the combustion system.

[0032] The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Modifications, which fall within the scope of the present invention, will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims. The systems described herein are not limited to the specific embodiments described herein, but rather portions of the various systems may be utilized independently and separately from other systems described herein.

[0033] Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. Moreover, references to “one embodiment” in the above description are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recitedfeatures. In accordance with the principles of the invention, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0034] Further aspects of the invention are provided by the subject matter of the following clauses:

[0035] A power generation system coupled to a power grid, the power generation system comprising: a gas turbine engine comprising: a compressor comprising an inlet and a recirculation inlet, wherein the inlet is oriented to receive an air flow; a combustion system; and a turbine configured to discharge an exhaust gas stream therefrom; a heat recovery steam generator configured to: extract heat from the exhaust gas stream; and discharge an exhaust gas recirculation stream therefrom; an exhaust gas recirculation line configured to channel the exhaust gas recirculation stream towards the compressor, wherein the exhaust gas recirculation line comprises: at least one recirculation cooler configured to cool the exhaust gas recirculation stream; and a recirculation blower configured to receive a cooled exhaust stream from the at least one recirculation cooler, and discharge a second exhaust stream towards the compressor; and a controller configured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected.

[0036] The power generation system in accordance with any of the preceding clauses, wherein in response to the detection of the grid event, the controller is further configured to: measure a temperature of the air flow entering the compressor inlet; measure a temperature of the exhaust gas recirculation stream discharged from the turbine; and compare the air flow and the exhaust gas recirculation stream temperatures.

[0037] The power generation system in accordance with any of the preceding clauses, wherein in response to the temperature of the air flow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to modulate an operating speed of the recirculation blower.

[0038] The power generation system in accordance with any of the preceding clauses, wherein the controller is further configured to modulate the operating speed of the recirculation blower to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

[0039] The power generation system in accordance with any of the preceding clauses, wherein the controller is further configured to modulate the operating speed of the recirculation blower to facilitate decreasing a temperature of flow entering the compressor recirculation inlet.

[0040] The power generation system in accordance with any of the preceding clauses, further comprising a recirculation stack configured to: receive the second exhaust stream from the recirculation blower; discharge a first portion of the second exhaust stream towards the compressor recirculation inlet; and discharge a second portion of the second exhaust stream to atmosphere.

[0041] The power generation system in accordance with any of the preceding clauses, wherein in response to the temperature of the air flow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to modulate a flow of the second exhaust stream by selectively opening the recirculation stack to channel the second portion of the second exhaust stream to atmosphere.

[0042] The power generation system in accordance with any of the preceding clauses, wherein the controller is further configured to modulate the flow of the second exhaust stream to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

[0043] The power generation system in accordance with any of the preceding clauses, further comprising a recirculation line configured to: selectively receive a portion of the second exhaust stream discharged from the recirculation blower; and mix the portion of the second exhaust stream with the cooled exhaust stream discharged from the at least one recirculation cooler.

[0044] The power generation system in accordance with any of the preceding clauses, wherein in response to the temperature of the air flow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to selectively modulate a flow of the second exhaust stream by selectively opening the recirculation line to channel the portion of the second exhaust stream towards the recirculation blower.

[0045] The power generation system in accordance with any of the preceding clauses, wherein the controller is further configured to modulate the flow of the second exhaust stream to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

[0046] The power generation system in accordance with any of the preceding clauses, wherein in response to the temperature of the air flow being higher than the temperature of the exhaust gas recirculation stream, the controller is further configured to: modulate a speed of the recirculation blower; and modulate a flow of the second exhaust stream.

[0047] The power generation system in accordance with any of the preceding clauses, wherein the controller is further configured to modulate the speed of the recirculation blower to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

[0048] The power generation system in accordance with any of the preceding clauses, wherein the controller is further configured to modulate the flow of the second exhaust stream to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

[0049] A power generation system coupled to a power grid, the power generation system comprising: a gas turbine engine comprising: a compressor comprising an inlet and a recirculation inlet, wherein the inlet is oriented to receive an air flow; a combustion system; and a turbine configured to discharge an exhaust gas stream therefrom; a heat recovery steam generator configured to: extract heat from the exhaust gas stream; and discharge an exhaust gas recirculation stream therefrom; an exhaust gas recirculation line configured to channel the exhaust gas recirculation stream towards the compressor, wherein the exhaust gas recirculation line comprises: at least one recirculation cooler configured to cool the exhaust gas recirculation stream; and a recirculation blower configured to receive a cooled exhaust stream from the at least one recirculation cooler, and discharge a second exhaust stream towards the compressor; a recirculation stack configured to: receive the second exhaust stream from the recirculation blower; discharge a first portion of the second exhaust stream towards the compressor recirculation inlet; and discharge a second portion of the second exhaust stream to atmosphere; and a controllerconfigured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected.

[0050] A controller coupled to one of a cooler, a blower, a recirculation stack, and a recirculation line to facilitate control of a power generation system coupled to a power grid.

[0051] While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A power generation system coupled to a power grid, the power generation system comprising: a gas turbine engine comprising: a compressor comprising an inlet and a recirculation inlet, wherein the inlet is oriented to receive an air flow; a combustion system; and a turbine configured to discharge an exhaust gas stream therefrom; a heat recovery steam generator configured to: extract heat from the exhaust gas stream; and discharge an exhaust gas recirculation stream therefrom; an exhaust gas recirculation line configured to channel the exhaust gas recirculation stream towards the compressor, wherein the exhaust gas recirculation line comprises: at least one recirculation cooler configured to cool the exhaust gas recirculation stream; and a recirculation blower configured to receive a cooled exhaust stream from the at least one recirculation cooler, and discharge a second exhaust stream towards the compressor; and a controller configured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected.

2. The power generation system of Claim 1, wherein in response to the detection of the grid event, the controller is further configured to: measure a temperature of the air flow entering the compressor inlet;measure a temperature of the exhaust gas recirculation stream discharged from the turbine; and compare the air flow and the exhaust gas recirculation stream temperatures.

3. The power generation system of Claim 2, wherein in response to the temperature of the air flow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to modulate an operating speed of the recirculation blower.

4. The power generation system of Claim 3, wherein the controller is further configured to modulate the operating speed of the recirculation blower to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

5. The power generation system of Claim 3, wherein the controller is further configured to modulate the operating speed of the recirculation blower to facilitate decreasing a temperature of flow entering the compressor recirculation inlet.

6. The power generation system of Claim 2 further comprising a recirculation stack configured to: receive the second exhaust stream from the recirculation blower; discharge a first portion of the second exhaust stream towards the compressor recirculation inlet; and discharge a second portion of the second exhaust stream to atmosphere.

7. The power generation system of Claim 6, wherein in response to the temperature of the air flow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to modulate a flow of the second exhaust stream by selectively opening the recirculation stack to channel the second portion of the second exhaust stream to atmosphere.

8. The power generation system of Claim 7, wherein the controller is further configured to modulate the flow of the second exhaust stream to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

9. The power generation system of Claim 2 further comprising a recirculation line configured to: selectively receive a portion of the second exhaust stream discharged from the recirculation blower; and mix the portion of the second exhaust stream with the cooled exhaust stream discharged from the at least one recirculation cooler.

10. The power generation system of Claim 9, wherein in response to the temperature of the air flow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to selectively modulate a flow of the second exhaust stream by selectively opening the recirculation line to channel the portion of the second exhaust stream towards the recirculation blower.

11. The power generation system of Claim 10, wherein the controller is further configured to modulate the flow of the second exhaust stream to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

12. The power generation system of Claim 9, wherein in response to the temperature of the air flow being higher than the temperature of the exhaust gas recirculation stream, the controller is further configured to: modulate a speed of the recirculation blower; and modulate a flow of the second exhaust stream.

13. The power generation system of Claim 12, wherein the controller is further configured to modulate the speed of the recirculation blower to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

14. The power generation system of Claim 13, wherein the controller is further configured to modulate the flow of the second exhaust stream to facilitate increasing a pressure of flow entering the compressor recirculation inlet.

15. A power generation system coupled to a power grid, the power generation system comprising: a gas turbine engine comprising:a compressor comprising an inlet and a recirculation inlet, wherein the inlet is oriented to receive an air flow; a combustion system; and a turbine configured to discharge an exhaust gas stream therefrom; a heat recovery steam generator configured to: extract heat from the exhaust gas stream; and discharge an exhaust gas recirculation stream therefrom; an exhaust gas recirculation line configured to channel the exhaust gas recirculation stream towards the compressor, wherein the exhaust gas recirculation line comprises: at least one recirculation cooler configured to cool the exhaust gas recirculation stream; and a recirculation blower configured to receive a cooled exhaust stream from the at least one recirculation cooler, and discharge a second exhaust stream towards the compressor; a recirculation stack configured to: receive the second exhaust stream from the recirculation blower; discharge a first portion of the second exhaust stream towards the compressor recirculation inlet; and discharge a second portion of the second exhaust stream to atmosphere; and a controller configured to facilitate stabilizing an output of the power generation system after a grid event of the power grid is detected.

16. A controller coupled to one of a cooler, a blower, a recirculation stack, and a recirculation line to facilitate control of a power generation system coupled to a power grid.

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