System for stabilizing gas turbine engine power output during a grid event - Patents.com

Abstract

A power generation system coupled to a power grid includes 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. The compressor of the gas turbine engine includes an inlet oriented to receive an airflow and a recirculation inlet. The 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 direct the exhaust gas recirculation stream toward the compressor. The exhaust gas recirculation stream includes at least one recirculation cooler and a recirculation blower.

Description

[Technical Field]

[0001] The present disclosure relates generally to gas turbine engines, and more particularly to a system that uses recirculated exhaust gas to reduce compressor flow turbulence and stabilize gas turbine engine output during grid events. [Background technology]

[0002] Gas turbine engines are widely used in industrial and power generation operations and typically include a compressor, a turbine, and a combustion system. The combustion system provides hot gas to drive a turbine, which drives a compressor. The compressor compresses air for combustion in the combustion system, which is used to generate usable power output for a power grid. In at least some gas turbine engines, flow through the compressor may be disrupted during operation due to a grid event in the power grid, such as a change in grid frequency. For example, the grid event may 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, the flow disruption may cause a reversal of flow through the compressor, which may destabilize the power output from the gas turbine engine during the grid event. Similarly, the grid event may cause flow disruption and a change in fuel-to-air ratio in the combustion system, which may lead to combustion instability and potential loss of flame or emergency shutdown of the gas turbine engine.

[0003] At least some known gas turbine engines may include modifications to the compressor and / or turbine to minimize flow disturbances during a grid event. Such modifications may attempt to increase the margin between the gas turbine engine's operating pressure ratio and the maximum pressure ratio before compressor surge can occur, known in the art as increasing surge margin. However, due to grid load limitations, known modifications may not adequately improve the surge margin to a level necessary to stabilize the gas turbine engine's output. Therefore, there is a need for a system that uses recirculated exhaust gas to mitigate compressor flow disturbances and stabilize the gas turbine engine's output during a grid event. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,828,912 Summary of the Invention

[0005] In one aspect, a power generation system coupled to a power grid is provided. The gas turbine engine includes a compressor, a combustion system, and a turbine. The compressor includes an inlet and a recirculation inlet, the inlet oriented to receive an airflow. The turbine 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 route the exhaust gas recirculation stream toward 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 the cooled exhaust stream from the at least one recirculation cooler and discharge a second exhaust stream toward the compressor. The controller is configured to facilitate stabilizing an output of the power generation system after a power grid event of the power grid is detected.

[0006] In another aspect, a power generation system coupled to a power grid is provided. The gas turbine engine includes a compressor, a combustion system, and a turbine. The compressor includes an inlet and a recirculation inlet, the inlet being oriented to receive an airflow. The turbine 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 route the exhaust gas recirculation stream toward 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 the cooled exhaust stream from the at least one recirculation cooler and discharge a second exhaust stream toward the compressor. The recirculation stack is configured to receive the second exhaust stream from the recirculation blower, discharge a first portion of the second exhaust stream toward the compressor recirculation inlet, and discharge a second portion of the second exhaust stream to the atmosphere. The controller is configured to facilitate stabilizing an output of the power generation system after a power grid event is detected on the power grid.

[0007] In yet another aspect, a controller is provided, the controller coupled to one of the chiller, the blower, the recirculation stack, and the recirculation line to facilitate control of a power generation system coupled to a power grid. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an exemplary power generation system. [Figure 2] 2 is a schematic diagram of an exemplary detection system for use with the power generation system of FIG. 1. [Figure 3] 1 is a schematic diagram of an exemplary power generation system including exhaust gas recirculation; [Figure 4] FIG. 2 is a schematic diagram of another exemplary power generation system including exhaust gas recirculation. [Figure 5]FIG. 2 is a schematic diagram of a further exemplary power generation system including exhaust gas recirculation. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments described herein relate to a system that uses recirculated exhaust gas to mitigate compressor flow disturbances and stabilize gas turbine engine output during a grid event. In an exemplary embodiment, a gas turbine engine powers a generator coupled to an electric power grid. During operation of the gas turbine engine, a grid event may occur that includes a change in the frequency of the electric power grid. For example, a change in the grid frequency outside a predetermined acceptable frequency range may result in a frequency mismatch between the generator and the electric power grid. However, to stabilize the frequency mismatch, a change in the power output by the gas turbine engine may be required. This may result in a flow disturbance through the compressor of the gas turbine engine.

[0010] The systems described herein facilitate controlling the inlet pressure of a gas turbine engine compressor during a grid event using the recirculated exhaust gas, thereby mitigating flow turbulence through the compressor and minimizing resultant destabilization of the gas turbine engine output. Advantages of the systems described herein include at least: (i) minimizing flow turbulence through the gas turbine engine compressor by including at least one of a recirculation cooler and / or a recirculation blower in the exhaust gas recirculation line; (ii) minimizing flow turbulence through the gas turbine engine compressor by further including a recirculation stack in the exhaust gas recirculation line; (iii) minimizing flow turbulence through the gas turbine engine compressor by further including a recirculation line in the exhaust gas recirculation line; and (iv) increasing surge margin of the gas turbine engine by a controller regulating at least one of the operating speed of the recirculation blower, the flow through the recirculation stack, and / or the flow through the recirculation line.

[0011] 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.

[0012] Unless otherwise indicated, approximating language such as "generally," "substantially," and "about" used herein indicates that the term so modified may apply only to an approximate degree, rather than to an absolute or complete degree, as would be recognized by one of ordinary skill in the art. Thus, values ​​modified by terms such as "about," "approximately," and "substantially" should not be limited to the exact value specified. In at least some instances, approximating language may correspond to the precision of an instrument for measuring the value. Furthermore, unless otherwise indicated, terms such as "first," "second," and the like are used herein merely as labels and are not intended to impose any ordering, positioning, or hierarchy requirements on the items referred to by these terms. Furthermore, for example, a reference to a "second" item does not require or preclude the presence of, for example, a "first" or lower-numbered item, or a "third" or higher-numbered item.

[0013] 1 is a schematic diagram of an exemplary power generation system 100. In the exemplary embodiment, the power generation system 100 includes a gas turbine engine assembly 102. The gas turbine engine assembly 102 includes a compressor 104, a combustor 106, and a turbine 108 coupled together in a serial flow relationship. During operation, the combustor 106 receives air from the compressor 104 and fuel from a fuel supply. The combustor 106 mixes the fuel and air to generate a fuel-air mixture, which is combusted to generate combustion gases. The combustion gases are channeled through the turbine 108 and discharged from the turbine 108 as a first exhaust gas stream 110. The compressor 104 includes a compressor inlet 116 and a compressor outlet 118. The turbine 108 includes a turbine inlet 120 and a turbine outlet 122.

[0014] 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 inlet 114. In some embodiments, the heat extracted from first exhaust gas stream 110 may be exhausted from HRSG 112 and 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 an electric generator 124 that generates electrical power using a working fluid flowing through gas turbine engine assembly 102.

[0015] In the exemplary embodiment, power generation system 100 further includes a controller 126 that is used to dynamically adjust the 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 air entering compressor 104 through compressor inlet 116. A lower temperature generally reduces the power consumed by compressor 104 and therefore increases the power supplied to generator 124. Furthermore, 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 exiting turbine 108 through turbine outlet 122. A lower temperature generally increases the power supplied to generator 124 by turbine 108.

[0016] 2 is a schematic diagram of an example detection system 200 that can be used with a power generation system, such as power generation system 100 (shown in FIG. 1). In the example embodiment, generator 124 is coupled to power grid 202 to provide generated power to power grid 202. In the example embodiment, generator 124 includes a first sensor 204 that can detect changes to power grid 202, such as a grid event that causes a change in grid frequency outside a predetermined acceptable frequency range. Controller 126 can 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 a proxy signal generated by power generation system 100 or power grid 202 as a precursor to a power grid event. For example, controller 126 can be in communication with first sensor 204 to detect a change in the frequency of power grid 202. First sensor 204 can measure the change in the frequency of power grid 202 to determine whether the change results in a grid frequency outside a predetermined acceptable frequency range. In the exemplary embodiment, controller 126 includes memory 206 and processor 208. Controller 206 may detect a grid event based on a comparison of data stored in memory 206 (e.g., a predetermined allowable frequency range), instructions stored in memory 206, and / or data analyzed by processor 208 (e.g., a measured change in grid frequency).

[0017] In the exemplary embodiment, compressor 104 adjusts the ambient temperature (e.g., temperature T amb ) that can detect the temperature (e.g., temperature T exhaust) can be detected by the data detection system 200. The controller 126 can facilitate stabilizing the output of the power generation system 100 (shown in FIG. 1 ) based on data received by the data detection system 200 from at least the second sensor 210 and / or the third sensor 212. For example, the controller 126 can detect an ambient temperature T amb and / or a second sensor 210 for detecting the exhaust temperature T exhaust The controller 126 may communicate with a third sensor 212 to detect the detected temperature T based on data stored in the memory 206, instructions stored in the memory 206, and / or data analyzed by the processor 208. amb and T exhaust can be compared.

[0018] Figure 3 is a schematic diagram of an exemplary power generation system 300 including exhaust gas recirculation. The embodiment shown in Figure 3 is similar to the embodiment shown in Figure 1, with differences described herein; therefore, the same reference numerals used in Figure 3 are used in Figure 3 as were used in Figure 1. An exhaust gas recirculation stream 302 is withdrawn downstream from the HRSG 112 and directed toward the compressor 104. A first recirculation cooler 304, a recirculation blower 306, and a second recirculation cooler 308 are each coupled between the HRSG 112 and the compressor 104. The recirculation blower 306 is coupled between the first recirculation cooler 304 and the second recirculation cooler 308, with the second recirculation cooler 308 being downstream of the recirculation blower 306.

[0019] In the exemplary embodiment, first recirculation cooler 304 receives exhaust gas recirculation stream 302 and outputs a cooled stream 310 to recirculation blower 306. Recirculation blower 306 receives cooled stream 310 and outputs a second stream 312 to second recirculation cooler 308. Second recirculation cooler 308 receives second stream 312 and outputs a cooled second stream 314 to compressor 104. Cooled second stream 314 is received at a compressor recirculation inlet 316 of compressor 104.

[0020] As described herein above, the controller 126 may detect a grid event in the power grid 202 (shown in FIG. 2). In response to the grid event being detected, the controller 126 may adjust the ambient temperature T amb and the exhaust temperature Texhaust. amb At operating conditions where Texhaust is lower than the exhaust temperature Texhaust, the controller 126 may adjust the power output of the power generation system 300 using the exhaust gas recirculation stream 302. Specifically, the controller 126 may cause the recirculation blower 306 to adjust the flow of the second flow 312 toward the compressor 104. Thus, the recirculation blower 306 may facilitate minimizing flow turbulence through the compressor 104.

[0021] In some embodiments, the controller 126 may increase the operating speed of the recirculation blower 306 to facilitate increasing the flow of the second flow 312 and the cooled second flow 314, thereby facilitating an increase in pressure proximate the compressor inlet 116. The increased pressure at the compressor inlet 116 facilitates stabilizing the flow through the compressor 104 and therefore, increasing the surge margin of the gas turbine assembly 102. In other embodiments, the controller 126 may further increase the operating speed of the recirculation blower 306 to facilitate decreasing the flow of the second flow 312 and the cooled second flow 314, thereby, increasing the pressure proximate the compressor inlet 116. The increased pressure proximate the compressor inlet 116 facilitates stabilizing the flow through the compressor 104 and therefore, increasing the surge margin of the gas turbine assembly 102.

[0022] Further, controller 126 may cause first recirculation cooler 304 and / or second recirculation cooler 308 to adjust the electrical power output by engine assembly 200. Specifically, controller 126 may adjust the flow of cooled stream 310 and / or cooled second stream 314 based on the cooled (i.e., reduced) temperature of the stream received by compressor 104 to facilitate increasing the output of compressor 104, thus resulting in reduced electrical power consumption. Further, controller 126 may adjust the flow of cooled stream 310 and / or cooled second stream 314 based on the cooled (i.e., reduced) temperature of the stream received by turbine 108 to facilitate increasing the output of turbine 108, thus resulting in increased electrical power supply by turbine 108 to generator 124.

[0023] Figure 4 is a schematic diagram of an exemplary power generation system 400 including exhaust gas recirculation. The embodiment shown in Figure 4 is similar to the embodiment shown in Figures 1 and 3, with differences described herein, and therefore the same reference numbers used in Figures 1 and 3 are used in Figure 4. In the exemplary embodiment, an exhaust gas recirculation stream 302 is withdrawn downstream from the HRSG 112 and directed toward the compressor 104. A recirculation stack 402 is coupled between the HRSG 112 and the compressor 104, with the recirculation stack 402 being downstream of the second recirculation cooler 308.

[0024] A grid event is detected in the power grid 202 (shown in FIG. 2) and the ambient temperature T amb is the exhaust temperature T exhaustIn response to determining that the exhaust gas recirculation stream 302 is lower than the reference speed, the controller 126 may modulate the power output by the power generation system 400 using the exhaust gas recirculation stream 302. Specifically, the controller 126 may cause the recirculation stack 402 to adjust the flow of the cooled second flow 314 toward the compressor 104. The recirculation stack 402 may be selectively opened by the controller 126 to reduce the flow of the cooled second flow 314 toward the compressor 104, thus facilitating lowering the temperature proximate the compressor inlet 116 and stabilizing the flow through the compressor 104. In some embodiments, the controller 126 may open the recirculation stack 402 in combination with adjusting the operating speed of the recirculation blower 306 (as described above with reference to FIG. 3 ) to facilitate stabilizing the flow through the compressor 104 and therefore increasing the surge margin of the gas turbine assembly 102.

[0025] FIG. 5 is a schematic diagram of an exemplary power generation system 500 including exhaust gas recirculation. The embodiment shown in FIG. 5 is similar to the embodiments shown in FIGS. 1, 3, and 4, with differences described herein; therefore, the same reference numbers used in FIGS. 1, 3, and 4 are used in FIG. 5. In the exemplary embodiment, an exhaust gas recirculation stream 302 is withdrawn downstream from the HRSG 112 and routed toward the compressor 104. A recirculation line 502 is coupled between the HRSG 112 and the compressor 104, an input end 504 of the recirculation line 502 is coupled between the second recirculation cooler 308 and the recirculation stack 402, and an output end 506 of the recirculation line 502 is coupled between the first recirculation cooler 304 and the recirculation blower 306. In some embodiments, the input end 504 and / or output end 506 of the recirculation line 502 may have alternative locations between the HRSG 112 and the compressor 104.

[0026] A grid event is detected in the power grid 202 (shown in FIG. 2) and the ambient temperature T amb is the exhaust temperature T exhaustIn response to determining that the exhaust gas recirculation stream 302 is lower than the reference pressure, the controller 126 may modulate the power output by the power generation system 500 using the exhaust gas recirculation stream 302. Specifically, the controller 126 may cause the recirculation line 502 to regulate the flow of the cooled second flow 314 toward the compressor 104. The recirculation line 502 may be selectively opened by the controller 126 at its input end 504 to direct a portion 508 of the cooled second flow 314 through the recirculation line 502 and away from the compressor 104, thus facilitating lowering the temperature proximate the compressor inlet 116 and stabilizing the flow through the compressor 104. In some embodiments, the controller 126 may open the recirculation line 502 in combination with adjusting the operating speed of the recirculation blower 306 (as described herein above with reference to FIG. 3 ) and / or opening the recirculation stack 402 (as described herein above with reference to FIG. 4 ) to facilitate stabilizing the flow through the compressor 104 and, therefore, increasing the surge margin of the gas turbine assembly 102.

[0027] A grid event is detected in the power grid 202 (shown in FIG. 2) and the ambient temperature T amb is the exhaust temperature T exhaustIn response to determining that the exhaust gas recirculation stream 302 is higher than the reference pressure, the controller 126 may modulate the power output by the power generation system 500 using the exhaust gas recirculation stream 302. Specifically, the controller 126 may cause the recirculation line 502 and / or the recirculation blower 306 to adjust the flow of the second flow 312 and / or the cooled second flow 314 toward the compressor 104. The operating speed of the recirculation blower 306 may be increased by the controller 126 while the recirculation line 502 is closed to facilitate increasing the pressure proximate the compressor inlet 116 and thus stabilizing the flow through the compressor 104. In some embodiments, generally, such an increase in the operating speed of the recirculation blower 306 may provide approximately a 0.3% increase in flow through the gas turbine engine assembly 102 for every 1% flow increase in the exhaust gas recirculation stream. Additionally, the operating speed of the recirculation blower 306 may be increased by the controller 126 while the recirculation line 502 is open to facilitate increasing the pressure adjacent to the compressor inlet 116 and therefore stabilizing the flow through the compressor 104. Additionally, the operating speed of the recirculation blower 306 may be increased by the controller 126 while the recirculation line 502 is moved from an open flow position to a closed flow position to facilitate increasing the pressure adjacent to the compressor inlet 116 and therefore stabilizing the flow through the compressor 104 and increasing the surge margin of the gas turbine assembly 102.

[0028] Described herein is an exemplary system for mitigating compressor flow disturbances and stabilizing gas turbine engine power output during a grid event using recirculated exhaust gas. The exemplary system described herein provides several advantages over conventional designs and processes, including at least minimizing flow disturbances through the compressor of the gas turbine engine and increasing the surge margin of the gas turbine engine, while also minimizing combustion system disturbances.

[0029] The above description is illustrative only, and those skilled in the art will recognize that changes can be made to the described embodiments without departing from the scope of the invention disclosed. Modifications that fall within the scope of the invention will be apparent to those skilled in the art in light of a review of the present disclosure, and such modifications are intended to fall within the scope of the appended claims. The systems described herein are not limited to the specific embodiments described herein; rather, portions of the various systems may be utilized independently and separately from other systems described herein.

[0030] 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 recited features. 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.

[0031] Further aspects of the invention are provided by the subject matter of the following clauses.

[0032] 1. A power generation system coupled to an electric power grid, the power generation system comprising: a gas turbine engine including a compressor having an inlet and a recirculation inlet, the inlet oriented to receive an airflow; a combustion system; and a turbine configured to discharge an exhaust gas stream; 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 toward the compressor, the exhaust gas recirculation line including at least one recirculation cooler configured to cool the exhaust gas recirculation stream and a recirculation blower configured to receive the cooled exhaust stream from the at least one recirculation cooler and discharge a second exhaust stream toward the compressor; and a controller configured to facilitate stabilizing an output of the power generation system after a grid event of the electric power grid is detected.

[0033] 10. The power generation system of any one of the preceding clauses, wherein in response to detecting a grid event, the controller is further configured to measure a temperature of an airflow entering the compressor inlet, measure a temperature of an exhaust gas recirculation stream exiting the turbine, and compare the temperatures of the airflow and the exhaust gas recirculation stream.

[0034] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust an operating speed of the recirculation blower in response to the temperature of the airflow being lower than the temperature of the exhaust gas recirculation stream.

[0035] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust an operating speed of the recirculation blower to facilitate increasing the pressure of the flow entering the compressor recirculation inlet.

[0036] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust an operating speed of the recirculation blower to facilitate reducing a temperature of the flow entering the compressor recirculation inlet.

[0037] 10. The power generation system of any one 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 toward the compressor recirculation inlet, and discharge a second portion of the second exhaust stream to the atmosphere.

[0038] 10. The power generation system of claim 9, wherein in response to the temperature of the airflow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to regulate the flow of the second exhaust stream by selectively opening the recirculation stack to route a second portion of the second exhaust stream to the atmosphere.

[0039] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust the flow of the second exhaust stream to facilitate increasing the pressure of the flow entering the compressor recirculation inlet.

[0040] 10. The power generation system of any one 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.

[0041] 10. The power generation system of claim 9, wherein in response to the temperature of the airflow being lower than the temperature of the exhaust gas recirculation stream, the controller is further configured to selectively adjust the flow of the second exhaust stream by selectively opening a recirculation line to direct a portion of the second exhaust stream toward the recirculation blower.

[0042] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust the flow of the second exhaust stream to facilitate increasing the pressure of the flow entering the compressor recirculation inlet.

[0043] 10. The power generation system of claim 1, wherein in response to the temperature of the airflow being greater than the temperature of the exhaust gas recirculation stream, the controller is further configured to adjust the speed of the recirculation blower to adjust the flow of the second exhaust stream.

[0044] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust the speed of the recirculation blower to facilitate increasing the pressure of the flow entering the compressor recirculation inlet.

[0045] 10. The power generation system of any one of the preceding clauses, wherein the controller is further configured to adjust the flow of the second exhaust stream to facilitate increasing the pressure of the flow entering the compressor recirculation inlet.

[0046] An electric power generation system coupled to an electric power grid, the system comprising: a gas turbine engine, the gas turbine engine including: a compressor having an inlet and a recirculation inlet, the inlet oriented to receive an airflow; a combustion system; and a turbine configured to discharge an exhaust gas stream; a heat recovery steam generator configured to extract heat from the exhaust gas stream and discharge an exhaust gas recirculation stream therefrom; and an exhaust gas recirculation line configured to channel the exhaust gas recirculation stream toward the compressor, the exhaust gas recirculation line configured to cool the exhaust gas recirculation stream. an exhaust gas recirculation line comprising at least one recirculation cooler configured to cool the exhaust gas from the at least one recirculation cooler and a recirculation blower configured to receive the cooled exhaust stream from the at least one recirculation cooler and discharge a second exhaust stream towards a compressor; a recirculation stack configured to receive the second exhaust stream from the recirculation blower and to discharge a first portion of the second exhaust stream towards a compressor recirculation inlet and 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 is detected on an electrical power grid.

[0047] A controller coupled to one of the chiller, the blower, the recirculation stack, and the recirculation line to facilitate control of the power generation system coupled to the power grid.

[0048] 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. [Explanation of symbols]

[0049] 100 Power Generation System 102 Gas turbine engine assembly 104 Compressor 106 Combustor 108 Turbine 110 Exhaust Gas Stream 112HRSG 114 Entrance 116 Compressor inlet 118 Compressor outlet 124 Generator 126 Controller 200 Detection System 202 Power Grid 204 First Sensor 206 memory 208 processors 210 Second Sensor 212 Third Sensor 300 Power Generation System 302 Exhaust Gas Recirculation Stream 304 First recirculation cooler 306 Recirculation Blower 308 Second Recirculation Cooler 310 Flow 312 Second Stream 314 Cooled Second Stream 316 Compressor recirculation inlet 400 Power Generation System 402 Recirculation Stack 500 Power Generation System 502 Recirculation Line 504 input terminal 506 Output terminal

Claims

1. A power generation system (100, 300, 400, 500) coupled to a power grid (202), the power generation system (100, 300, 400, 500) comprising:

1. A gas turbine engine, comprising: a compressor (104) having an inlet (116) and a recirculation inlet (316), the inlet (116) oriented to receive an air flow; a combustion system (106); a turbine (108) configured to discharge an exhaust gas stream (110); A heat recovery steam generator (112), extracting heat from said exhaust gas stream (110); a heat recovery steam generator (112) configured to discharge the exhaust gas recirculation stream (302) therefrom; an exhaust gas recirculation line (502) configured to direct the exhaust gas recirculation stream (302) toward the compressor (104), the exhaust gas recirculation line (502) comprising: at least one recirculation cooler (304) configured to cool the exhaust gas recirculation stream (302); an exhaust gas recirculation line (502) comprising: a recirculation blower (306) configured to receive a cooled exhaust stream (310) from the at least one recirculation cooler (304) and to discharge a second exhaust stream (312) toward the compressor (104); a controller configured to facilitate stabilizing an output of the power generation system after a grid event is detected in the power grid.

2. In response to the detection of the grid event, the controller (126): The temperature (T ａｍｂ ) is measured, The temperature (T ｅｘｈａｕｓｔ ) is measured, The temperature (T ａｍｂ , T ｅｘｈａｕｓｔ 10. The power generation system (100, 300, 400, 500) of claim 1, further configured to compare

3. The temperature (T ａｍｂ ) is the temperature (T ｅｘｈａｕｓｔ 3. The power generation system of claim 2, wherein the controller is further configured to adjust the operating speed of the recirculation blower in response to the temperature being lower than the reference temperature.

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

5. 4. The power generation system of claim 3, wherein the controller is further configured to adjust the operating speed of the recirculation blower to facilitate reducing a temperature of a flow entering the compressor recirculation inlet.

6. receiving the second exhaust stream (312) from the recirculation blower (306); Discharging a first portion of the second exhaust stream (312) toward a recycle inlet (316) of the compressor (104); The power generation system (100, 300, 400, 500) of claim 2, further comprising a recirculation stack (402) configured to discharge a second portion of the second exhaust stream (312) to the atmosphere.

7. The temperature (T ａｍｂ ) is the temperature (T ｅｘｈａｕｓｔ 7. The power generation system of claim 6, wherein in response to the second portion of the exhaust stream being lower than the first portion of the second exhaust stream, the controller is further configured to regulate a flow of the second exhaust stream by selectively opening the recirculation stack to route the second portion of the second exhaust stream to atmosphere.

8. 8. The power generation system (100, 300, 400, 500) of claim 7, wherein the controller (126) is further configured to regulate the flow of the second exhaust stream (312) to facilitate increasing the pressure of the flow entering the compressor (104) recirculation inlet (316).

9. selectively receiving a portion of the second exhaust stream (312) discharged from the recirculation blower (306); 3. The power generation system of claim 2, further comprising a recirculation line configured to mix the portion of the second exhaust stream with the cooled exhaust stream discharged from the at least one recirculation cooler.

10. The temperature (T ａｍｂ ) is the temperature (T ｅｘｈａｕｓｔ 10. The power generation system of claim 9, wherein in response to the temperature being lower than the temperature at which the second exhaust stream is exhausted, the controller is further configured to selectively adjust the flow of the second exhaust stream by selectively opening the recirculation line to route the portion of the second exhaust stream toward the recirculation blower.

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

12. The temperature (T ａｍｂ ) is the temperature (T ｅｘｈａｕｓｔ ), the controller (126) The power generation system (100, 300, 400, 500) of claim 9, further configured to adjust a speed of the recirculation blower (306) to adjust a flow of the second exhaust stream (312).

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

14. 14. The power generation system (100, 300, 400, 500) of claim 13, wherein the controller (126) is further configured to regulate the flow of the second exhaust stream (312) to facilitate increasing the pressure of the flow entering the compressor (104) recirculation inlet (316).

15. A power generation system (100, 300, 400, 500) coupled to a power grid (202), comprising:

1. A gas turbine engine, comprising: a compressor (104) having an inlet (116) and a recirculation inlet (316), the inlet (116) oriented to receive an air flow; a combustion system (106); a turbine (108) configured to discharge an exhaust gas stream (110); A heat recovery steam generator (112), extracting heat from said exhaust gas stream (110); a heat recovery steam generator (112) configured to discharge the exhaust gas recirculation stream (302) therefrom; an exhaust gas recirculation line (502) configured to direct the exhaust gas recirculation stream (302) toward the compressor (104), the exhaust gas recirculation line (502) comprising: at least one recirculation cooler (304) configured to cool the exhaust gas recirculation stream (302); an exhaust gas recirculation line (502) comprising: a recirculation blower (306) configured to receive a cooled exhaust stream (310) from the at least one recirculation cooler (304) and to discharge a second exhaust stream (312) toward the compressor (104); A recirculation stack (402) comprising: receiving the second exhaust stream (312) from the recirculation blower (306); Discharging a first portion of the second exhaust stream (312) toward a recycle inlet (316) of the compressor (104); a recirculation stack (402) configured to discharge a second portion of the second exhaust stream (312) to atmosphere; a controller configured to facilitate stabilizing an output of the power generation system after a grid event is detected in the power grid.

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

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