Systems and methods for using the base load power of a backup GT system to improve GT performance or grid stability.

Abstract

A system and method are provided that uses baseload power of a reserve GT system to improve GT performance or grid stability. The system includes a GT system of a power plant operatively coupled to a generator to generate power at baseload all the time. A first portion of the baseload power of the GT system is sent to the power grid. When the power demand from the power grid does not exceed a threshold, a second portion of the baseload power of the GT system is sent to a compressor to generate compressed air for the second GT system, improving efficiency. When the power demand from the power grid exceeds a threshold, one-third of the baseload power of the GT system is sent to the power grid. The GT system is always operated at baseload, but can rapidly supply increased power to the power grid, like a conventional spinning reserve. The system improves efficiency by operating all GT systems at baseload and supplying compressed air to the second GT system when grid power demand allows.

Description

Technical Field

[0001] The present disclosure generally relates to power plant control systems, and more particularly to operating a standby gas turbine (GT) system at base load and using a portion of the base load power to operate one or more compressors to supply air for injection into other GT systems if grid power demand permits, and supplying power to the grid (system) if grid power demand is required. As a result, the performance of one or more GT systems and / or grid stability can be improved.

Background Art

[0002] Power plants supply power to a wide - area power grid. In some cases, a power plant may be equipped with multiple gas turbine (GT) systems. One example of this can be seen in US Patent Application No. 2020 / 0295573 (September 17, 2020) filed with US Pat.App.Pub.Batsch-Smith. To operate a power plant efficiently and maximize the life of the GT system, it is best to operate the gas turbine in a full - load or near - full - load condition called "baseload". Note that baseload may not include a small amount of reserve called "primary control reserve" for automatically responding to frequency changes in the electric grid in the GT system. For a stable power grid, it is necessary that the generated power of the power plants supplying power to the grid always matches the power demand regardless of fluctuations in demand. Therefore, in order to maintain a stable power grid, power plants usually need to maintain a certain amount of additional capacity (capacity) or standby load called "spinning reserve" so that additional power can be supplied when needed. The primary control reserve of the GT system cannot respond to power demand fluctuations from the wide - area power grid.

[0003] To cope with demand fluctuations, one GT system is designated as a spinning reserve or simply a backup GT system and is not operated under base load. For example, a backup GT system is operated at 50-100% load depending on grid power demand. Therefore, in a power plant with 10 GT systems, if there is no increase in demand, for example, 5% can be designated as a spinning reserve and 95% of the capacity can be supplied. In this way, when power demand increases, the backup capacity of the backup GT system (e.g., up to 50%) can be utilized to generate more power quickly and maintain the stability of the power grid.

[0004] Operating backup GT systems presents many challenges. For example, operating a GT system below baseload levels is highly inefficient due to poor fuel combustion efficiency, increased emissions, and generally difficulty in controlling output fluctuations. Operating backup GT systems also incurs costs for transmission companies that purchase electricity from power plants, as they have to pay for unused capacity at the power plants and the inefficient operation of backup GT systems. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 295573 [Overview of the Initiative]

[0006] All aspects, examples, and features described below can be combined in any way that is technically possible.

[0007] One aspect of the present disclosure provides a system. The system comprises: a first GT system operably coupled to a first generator for generating baseload power, wherein a first portion of the baseload power generated by the first GT system is transmitted to a wide-area power grid controlled by a transmission system operator (TSO); a second GT system operably coupled to a second generator for generating power; a compressor operably coupled to the second GT system for supplying compressed air, configured to be selectively powered by a second portion of the baseload power generated by the first GT system; and a controller. The controller is configured to instruct the compressor to send the second portion of the baseload power generated by the first GT system to generate compressed air for the second GT system in response to a power demand from the wide-area power grid not exceeding a threshold, and to instruct the compressor to send the third portion of the baseload power generated by the first GT system to the wide-area power grid in response to a power demand from the wide-area power grid exceeding a threshold.

[0008] Another aspect of the present disclosure includes any of the preceding aspects and further includes a plurality of third GT systems co-located with a first GT system, each third GT system being operably connected to a third generator to generate base load power for transmission to a wide-area power grid.

[0009] Another aspect of this disclosure includes any of the preceding aspects, wherein the second GT system is at least one of a plurality of third GT systems.

[0010] Another aspect of the present disclosure includes any of the preceding aspects, wherein at least two of the first, second, and third generators are the same generator.

[0011] Another aspect of this disclosure includes any of the preceding aspects, wherein the compressor and the second GT system are located at a different geographical location from the first GT system.

[0012] Another aspect of the present disclosure includes any of the preceding aspects, wherein a third portion of the base load power generated by the first GT system is maintained as a primary control reserve by the governor of the first GT system.

[0013] Another aspect of the present disclosure includes any of the preceding aspects, wherein a second portion of the baseload power generated by the first GT system is sent directly to a compressor to generate compressed air for the second GT system, without passing through a wide-area power grid.

[0014] Another aspect of this disclosure includes any of the preceding aspects, wherein the control device is located in a TSO of a wide-area power grid.

[0015] Another aspect of the present disclosure includes any of the preceding aspects, wherein a third portion of the baseload power generated by the first GT system is transmitted to a wide-area power grid, and power from the wide-area power grid is sent to a compressor to generate compressed air for the second GT system.

[0016] Another aspect of the present disclosure includes any of the preceding aspects, wherein, in response to the controller instructing that a third portion of the baseload power generated by the first GT system be sent to the wide-area power grid, the controller adjusts at least the fuel flow rate of the second GT system to maintain the output of the second GT system.

[0017] One aspect of the present disclosure provides a system. The system comprises: a first GT system operably coupled to a first generator for generating baseload power, the baseload power being transmitted to a wide-area power grid controlled by a Transmission System Operator (TSO); a second GT system operably coupled to a second generator for generating power for transmission to the wide-area power grid; a compressor configured to be selectively powered by power from the wide-area power grid, and operably coupled to supply compressed air to the second GT system; and a controller. The controller increases the power from the wide-area power grid to the compressor in response to a threshold being exceeded, thereby increasing the amount of compressed air produced for the second GT system; and decreases the power from the wide-area power grid to the compressor in response to a threshold being not exceeded, thereby decreasing the amount of compressed air produced for the second GT system.

[0018] Another aspect of the present disclosure includes any of the preceding aspects and further includes a plurality of third GT systems co-located with a first GT system, each third GT system being operably connected to a third generator to generate base load power for transmission to a wide-area power grid.

[0019] Another aspect of this disclosure includes any of the preceding aspects, wherein the second GT system is at least one of a plurality of third GT systems.

[0020] Another aspect of this disclosure includes any of the preceding aspects, wherein the compressor and the second GT system are located at a different geographical location from the first GT system.

[0021] Another aspect of the present disclosure includes any of the preceding aspects, wherein, in response to the controller instructing the shutdown of power transmission from the wide-area power grid to the compressor, the controller adjusts at least the fuel flow rate of the second GT system in order to maintain the output of the second GT system.

[0022] Another aspect of the present disclosure includes any of the preceding aspects, and the control device is arranged at the TSO of the wide-area power grid.

[0023] One aspect of the present disclosure provides a method. The method includes transmitting a first portion of the base load power generated by a first GT system coupled to a first generator to a wide-area power grid controlled by a Transmission System Operator (TSO); in response to the power demand from the wide-area power grid not exceeding a threshold, transmitting a second portion of the base load power generated by the first GT system to a compressor, the compressor being operably coupled to deliver compressed air to a second GT system, the second GT system being operably coupled to a second generator to generate power; and in response to the power demand from the wide-area power grid exceeding the threshold, transmitting a third portion of the base load power generated by the first GT system to the wide-area power grid.

[0024] Another aspect of the present disclosure includes any of the preceding aspects, and further includes transmitting the base load power generated by a plurality of third GT systems and operably coupled to a third generator to the wide-area power grid, the plurality of third GT systems being arranged at the same location as the first GT system, and the second GT system being at least one of the plurality of third GT systems.

[0025] Another aspect of the present disclosure includes any of the preceding aspects, and the compressor and the second GT system are arranged at a geographical location different from that of the first GT system.

[0026] Another aspect of the present disclosure includes any of the preceding aspects, and in response to transmitting a third portion of the base load power generated by the first GT system to the wide-area power grid, at least the fuel flow rate of the second GT system is adjusted to maintain the output of the second GT system.

[0027] Two or more aspects described in this disclosure may be combined to form embodiments not particularly described herein, including those described in the summary.

[0028] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Brief Description of the Drawings

[0029] These and other features of the disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure, taken in conjunction with the accompanying drawings that illustrate various embodiments of the disclosure. [Figure 1] It is a schematic diagram of an exemplary power plant system according to the prior art. [Figure 2] It is a schematic diagram of a system according to an embodiment of the disclosure. [Figure 3] It is a schematic diagram of an exemplary GT system according to an embodiment of the disclosure. [Figure 4] It is a cross-sectional view of the compressor portion of the GT system of FIG. 3. [Figure 5] It is a cross-sectional view of the turbine portion of the GT system of FIG. 3. [Figure 6] It is a flowchart of a method of operating a system according to an embodiment of the disclosure. [Figure 7] It is a schematic diagram of a system according to another embodiment of the disclosure. [Figure 8] It is a flowchart of a method of operating a system according to another embodiment of the disclosure. [Figure 9] It is a schematic diagram of a system according to an additional embodiment of the disclosure.

[0030] Note that the drawings of the disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure and should not therefore be considered as limiting the scope of the disclosure. In the drawings, like numbers represent like elements between the drawings. [Modes for carrying out the invention]

[0031] Firstly, in order to clearly describe the subject matter of this disclosure, it is necessary to select specific terminology when referring to and describing the relevant mechanical components within a turbomachine used to generate electricity. Wherever possible, common industry terms will be used and used in a manner consistent with their common meaning. Unless otherwise noted, such terms should be given a broad interpretation consistent with the context of this application and the appended claims. Those skilled in the art will understand that certain components are often referred to using multiple different or overlapping terms. What is described as a single component in this specification may include and refer to a component consisting of multiple components in another context. Or, what is described as consisting of multiple components in this specification may be referred to as a single component elsewhere.

[0032] In addition, several descriptive terms may be used periodically in this specification, and it would be beneficial to define these terms at the beginning of this section. Unless otherwise noted, these terms and their definitions are as follows: As used herein, the terms “downstream” and “upstream” refer to the direction of fluid flow, such as the working fluid through a turbine engine, the airflow through a combustor, or the coolant flow through one of the turbine's components. The term “downstream” corresponds to the direction of fluid flow, while the term “upstream” refers to the direction opposite to the flow (i.e., the direction in which the flow originates). The terms “forward” and “aft” are not further specified and simply refer to direction, with “forward” referring to the front of the engine or the compressor end, and “aft” referring to the rear section of the turbomachine.

[0033] Often, it is necessary to describe components positioned at different radial locations relative to the central axis. The term "radial" refers to movement or position perpendicular to the axis. For example, if a first component is located closer to the axis than a second component, this specification states that the first component is "radially inward" or "inboard" than the second component. Conversely, if a first component is located further from the axis than a second component, this specification may state that the first component is "radially outward" or "outboard" of the second component. The term "axial" refers to movement or position parallel to the axis. Finally, the term "circumferential" refers to movement or position around an axis. It will be understood that such terms may also be applied in relation to the central axis of a turbine.

[0034] Furthermore, several descriptive terms may be used regularly in this specification, as described below. The terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to imply the position or importance of individual components.

[0035] The terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit the disclosure. Where used herein, the singular forms “a,” “an,” and “the” are intended to include the plural form unless the context clearly indicates otherwise. Where used herein and in the claims, the terms “comprises” and / or “comprising” identify the presence of a described feature, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. “Optional” or “optionally” means that the event or situation described thereafter may or may not occur, or the component or element described thereafter may or may not exist, and that the description includes examples in which the event or component exists and examples in which it does not occur or does not exist.

[0036] When an element or layer is referred to as “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or there may be an intervening element or layer. In contrast, when an element is said to be “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening element or layer. When power is “directed” to a structure, there may be no intervening structure. Other words used to describe relationships between elements should be interpreted similarly (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any combination of one or more of the enumerated items relating to it.

[0037] As used herein, "baseload power" refers to the power output when a particular gas turbine (GT) system is operating at full capacity. It should be noted that baseload power may exclude the "primary control reserve," which is a portion of the gas turbine output automatically controlled by each governor of any GT system to provide backup power against frequency changes to the grid, i.e., instability caused by imbalances between demand and generation. The primary control reserve provides a very fast response to changes, such as 15 seconds. The "spinning reserve" refers to a portion of the power plant capacity reserved for when additional power is requested, i.e., when additional power is requested by the transmission system operator (TSO) of the wide-area power grid. The "secondary control reserve" is a portion of the spinning reserve reserved for automatic generation control (AGC) (also known as load frequency control (LFC)) by the TSO.

[0038] In this context, TSO refers to an entity entrusted with transmission control to and from the wide-area power grid. The areas covered by TSOs vary at the national and regional levels, such as state-based independent grid operators in the United States. TSOs control power plants and wide-area transmission to maintain the stability of the wide-area power grid. AGC is a system that frequently, quickly, and automatically adjusts the output of multiple generators at different power plants in response to load changes, for example, based on grid frequency, so that load and generation are continuously matched. An AGC system can be activated, for example, within about 10 minutes.

[0039] When the system frequency increases, more power is produced than is used, resulting in accelerated power generation at power plants. In this case, AGC may reduce the output of one or more power plants. When the system frequency decreases, there is more load than current power can supply, causing power plant generators to slow down. In this case, AGC may increase the output of one or more power plants. The "tertiary control reserve" is a portion of the spinning reserve that the TSO can manually adjust when the tertiary control reserve is insufficient to maintain stability. The response time here is, for example, about 30 minutes.

[0040] Referring to Figure 1, power plants 100 supply power to a wide-area electric grid 102 (hereinafter simply referred to as "grid 102"). In some cases, power plants 100 may include a number of GT systems 110 at a particular site. Each GT system 110 may be connected to a generator 114 or may share a generator. To operate power plants 100 efficiently and achieve the longest possible lifespan for GT systems 110, it is best to operate GT systems 110 at base load power. A stable grid requires that the power generated by power plants 100 supplying power to grid 102 always matches the electricity demand, regardless of fluctuations in demand. As a result, to maintain a stable grid, power plants 100 are usually required to maintain a spinning reserve that can supply additional power when needed.

[0041] Figure 1 illustrates a spinning reserve GT system 110R. The reserve GT system 110R can operate at 50-100% load depending on electricity demand. Thus, in the case of an exemplary power plant 100 having 10 GT systems 110, the power plant typically supplies 95% of its capacity, with 5% being the spinning reserve when there is no increase in demand. In this way, when electricity demand increases, the additional capacity of the GT systems 110R of power plant 100, i.e., up to 50%, can be used to generate electricity quickly to maintain the stability of the grid 102. The amount of spinning reserve to be employed can vary based on many factors, such as the average increase / decrease in demand over time, geographic location, and grid infrastructure. Disadvantageously, operating the reserve GT system 110R at levels below base load or with high levels of output fluctuation is highly inefficient, for example, because the system burns fuel inefficiently, emissions increase, and it is generally difficult to control against output fluctuations. Furthermore, operating the backup GT system 110R would incur costs for the power supply company purchasing energy from power plant 100, as it would cover the unused capacity of power plant 100 and the inefficient operation of backup GT system 110R.

[0042] Embodiments of the present disclosure include a system comprising one or more power plants having a first auxiliary GT system operably coupled to a first generator to communicate with a control device and generate base-load power. The power plant may include any number of other first GT systems operably coupled to the generator to generate base-load power for a transmission grid controlled by a TSO. One or more compressors are selectively powered by the auxiliary GT system. A first portion of the base-load power of the auxiliary GT system is transmitted to the transmission grid. If the power demand from the TSO does not exceed a threshold, the controller sends a second portion of the base-load power of the one or more auxiliary GT system to one or more compressors to generate compressed air for one or more second, supplemented GT system(s) to improve the efficiency of the latter. If the power demand from the TSO exceeds a threshold (e.g., if demand increases), the controller instructs the second portion of the base-load power of the auxiliary GT system to be transmitted to the transmission grid.

[0043] By continuously generating base load power, the system reduces fuel consumption, improves combustion temperature stability, extends the lifespan of the backup and supplemental GT systems (reducing maintenance), and lowers emissions. When grid power demand increases, the system shuts down the compressor and transmits power to the grid from the backup GT system to maintain grid stability. In this way, the system also serves the role of a conventional spinning reserve, but without the drawbacks.

[0044] Embodiments of System 200 according to embodiments of the present disclosure will be described with reference to Figures 2 and 6-9. System 200 includes one or more power plants 202 represented by stacked rectangles. Each power plant 202 includes a GT system 210R operably coupled to a first generator 212 to generate base load power. For convenience of explanation, GT system 210R is referred to as “reserve GT system 210R” as it is one of several other GT systems 220 that provides reserve power to the grid 204 when needed. However, reserve GT system 210R operates at base load power (full capacity) as defined herein and does not provide spinning reserve as defined herein.

[0045] Each power plant 202 may also include one or more additional GT systems 220. For convenience of explanation, the GT systems 220 are referred to as “primary GT systems 220,” since their function is to supply primary, base-load (full capacity) power to the grid 204 with little to no surplus capacity other than primary control reserve, as defined herein. As previously stated, primary control reserve represents a third portion of base-load power generated, for example, by a backup GT system 210R and maintained by the governor 223 of the backup GT system 210R (the governor of the primary GT system 220 is not shown for clarity).

[0046] In certain embodiments, system 200 may include a plurality of primary GT systems 250 located in the same position as (co-located with) a backup GT system 210R. In Figure 2, for example, nine primary GT systems 220 are illustrated, but any number may be provided. Each primary GT system 220 may be operably coupled to a generator 214 to generate base load power for transmission to the grid 204. Although each primary GT system 220 is shown with its corresponding generator 214, it will be recognized that certain primary GT systems 220 may share a generator.

[0047] GT systems 210R and 220 may each include a GT controller 216, or they may share a GT controller 216 (shown only in Figures 2 and 7 for clarity). One or more GT controllers 216 may be part of an overall power plant control system (not shown).

[0048] Referring to Figure 3, cross-sectional views of exemplary GT systems 210R, 220, and 250 according to embodiments of the present disclosure are shown. Generally, GT systems 210R, 220, and 250 operate by extracting energy from a pressurized flow of hot gas produced by the combustion of fuel in a flow of compressed air. GT systems 210R, 220, and 250 may be configured to include an axial compressor 222 mechanically coupled to a downstream turbine section or turbine 224 by a common shaft or rotor, and one or more combustors 226 positioned between the compressor 222 and the turbine 224. GT systems 210R, 220, and 250 may be formed around a common shaft 228 having a central axis A.

[0049] Figure 4 shows a cross-sectional view of an exemplary portion of a multi-staged axial compressor 222 that may be used in the GT systems 210R and 220 of Figure 2. The compressor 222 may have multiple stages, each stage including rows of compressor rotor blades 230 and rows of compressor stator blades 232. Thus, the first stage may include rows of compressor rotor blades 230 that rotate around a central shaft, followed by rows of compressor stator blades 232 that remain stationary during operation.

[0050] Figure 5 shows an exemplary turbine section or partial cross-sectional view of a turbine 224 that may be used in the GT systems 210R and 220 of Figure 2. The turbine 224 may also include multiple stages. Three exemplary stages are shown, but there may be more or fewer stages. Each stage may include multiple turbine nozzles or stator blades 234 that remain stationary during operation and multiple turbine rotor blades 236 that rotate around the shaft during operation. The turbine stator blades 234 are generally spaced apart from each other in the circumferential direction and fixed to the outer casing around the axis of rotation. The turbine rotor blades 234 may be mounted on a turbine wheel or rotor disk (not shown) so as to rotate around a central axis A (Figure 2). It will be understood that the turbine stator blades 234 and turbine rotor blades 236 are in the hot gas path or working fluid flow path through the turbine 224. The flow direction of the combustion gas or working fluid within the working fluid passage is indicated by an arrow.

[0051] Referring to Figures 3-5, in one example of the operation of the gas turbine 224, the airflow can be compressed by the rotation of the compressor rotor blades 230 in the axial compressor 222. In one or more combustors 226, when the compressed air is mixed with fuel and ignited, energy is released. As a result, the flow of hot gas or working fluid from one or more combustors 226 is directed onto the turbine stator blades 236, inducing the rotation of the turbine rotor blades 234 around the shaft 228. In this way, the energy of the working fluid flow is converted into mechanical energy of the rotating blades, and, considering the connection between the rotating blades and the shaft, into the rotating shaft. The mechanical energy of the shaft 228 is used to drive the rotation of the compressor rotor blades 230, generating a desired or sufficient supply of compressed air. Furthermore, the mechanical energy of the shaft 228 can then be used to drive the rotation of one or more generators 212, 214 (Figure 2) coupled to one or more GT systems 210R, 220 (Figure 2) to generate electricity.

[0052] Returning to Figure 2, system 200 also includes a controller 238 that controls the transmission of base load power from the auxiliary GT system 210R. Controller 238 may include any currently known or later developed electromechanical control system that can direct the transmission to different loads. Controller 238 may be part of an overall power plant control system (e.g., controller 216) or it may be a separate system. In Figure 2, controller 238 is shown as being located together with the power plant 202. In one embodiment, controller 238 is controlled by the power plant 202 without any additional interaction with the TSO 239, which is typically performed as part of the overall operation of the power plant 202. In other specific embodiments, controller 238 may be controlled by the TSO 239. In one embodiment, controller 238 is located in the power plant 202 but is controlled by the TSO 239. In alternative embodiments, controller 238 may be located elsewhere, such as in the TSO 239. As shown in Figure 2, the controller 238 can direct a first portion 237 of the base load power generated by the auxiliary GT system 210R to the grid 204 controlled by the TSO 239.

[0053] System 200 also includes a power compressor 242 configured to be selectively powered by the auxiliary GT system 210R. Compressor 242 may include any currently known or later developed standalone compressors, separate from compressor 222 of GT system 210R, 220. Although one compressor 242 is illustrated, any number of standalone compressors may be provided. Compressor 242 may have any currently known or later developed structure. For example, compressor 242 may be an axial compressor, having a structure similar to compressor 222 of GT system 210R, 220 (Figures 3 and 4). More specifically, compressor 242 may have multiple stages, each stage including a row of compressor rotor blades and a row of compressor stator blades, the latter rotating around a central shaft. In other cases, compressor 242 may take the form of a radial compressor. In any case, the rotation of the compressor rotor blades inside the compressor 242 compresses the flow of compressed air 244.

[0054] In system 200, the controller 238 can instruct the compressor 242 to supply power with a second portion 246 of the base load power generated by the auxiliary GT system 210R. In system 200, the compressor 242 is operably coupled to supply compressed air 244 to the GT system 250. For illustrative purposes, since the GT system 250 receives supplemental air from the compressor 242, it may be referred to herein as the “supplemented GT system 250”. The supplemented GT system 250 may include the auxiliary GT system 210R and / or any one or more primary GT systems 220 in system 200. The supplemented GT system 250 may be located in the same position as one or more primary GT systems 220 and / or the auxiliary GT system 210R. In any case, the supplemented GT system 250 can be operably coupled to generators 212, 214 to generate power. In the example in Figure 2, the supplemental GT system 250 may be one or more of the primary GT system 220 and / or auxiliary GT system 210R. In alternative embodiments described herein (see Figure 9), the compressor 242 and the supplemental GT system 250 may be located in different geographical locations from one or more primary GT systems 220 and / or auxiliary GT systems 210R, for example, in different remote power plants 202.

[0055] Figure 6 shows a flowchart illustrating the operation of system 200, more specifically the controller 238, according to an embodiment of the present disclosure. Referring to Figures 2 and 6, in process step P1, the backup GT system 210R operates at base load. According to an embodiment of the present disclosure, the backup GT system 210R always operates at base load, thus eliminating the inefficiencies caused by supplying spinning backup. In process step P1, a first portion 237 of the base load power generated by the backup GT system 210R coupled to the generator 212 is sent to the grid 204. The first portion 237 may be any portion of the capacity of the backup GT system 210R, for example, 50%. Also in process step P1, base load power generated by multiple primary GT systems 220 and operably coupled to one or more generators 214 is sent to the grid 204. As shown in Figure 2, the primary GT system 220 is not required in all cases, but may be co-located with the auxiliary GT system 210R.

[0056] In process step P2, the controller 238 determines whether the power demand (request) from TSO239 to grid 204 exceeds a threshold, i.e., whether the power demand is greater than a threshold. The threshold can be any currently known or later developed value that indicates that the power demand from TSO239 to grid 204 requires additional power to be generated by the power plant 202. The threshold can be created, for example, as part of a currently known or later developed AGC algorithm that typically triggers the use of a secondary spinning reserve. Such algorithms are well known and require no further explanation. Alternatively, the threshold may be manually identified by the power plant 202 without the TSO239 knowing, and the controller 238 may be activated, or it may be manually identified by TSO239 and the controller 238 may be activated.

[0057] If the result in process step P2 is "NO", it indicates that the power demand from TSO239 to grid 204 does not exceed the threshold, i.e., that there is no need to supply backup power. In this case, in process step P3, controller 238 instructs compressor 242 to send a second portion 246 of the base load power generated by backup GT system 210R to generate compressed air for supplemental GT system 250. Compressor 242 is turned on if it is not already on. As previously stated, compressor 242 is operably coupled to supply compressed air 244 to one or more supplemental GT systems 250 which are operably coupled to generators 212, 214 to generate power. Power from one or more supplemental GT systems 250 can be used for grid 204 or for other purposes.

[0058] Compressed air 244 is supplied (directly) to any one or more supplemental GT systems 250 in known manner. As is recognized, using supplemental compressed air 244 with supplemental GT systems 250 can improve the efficiency and performance of those GT systems beyond what is possible with the compressed air provided by their respective axial compressors 222 (Figure 3). In this way, a second portion 246 of the base load power of the auxiliary GT system 210R, which would normally be an unused spinning reserve, is used to improve the efficiency and performance of one or more supplemental GT systems 250, and therefore the efficiency and performance of one or more power plants 202. In Figure 2, as indicated by the solid arrows, the supplemental GT system 250 may be at least one of a plurality of primary GT systems 220. In other embodiments, as indicated by the solid and dashed arrows, the supplemental GT system 250 may optionally be any number of primary GT systems 220 and / or auxiliary GT systems 210R.

[0059] Continuing with the flowchart in Figure 6, if the answer in process step P2 is "YES", it indicates that the demand for power from TSO239 for grid 204 exceeds a threshold, meaning that power plant 202 and the backup GT system 210R need to supply more power to TSO239 for grid 204, in particular, to maintain stability and meet the demand. Here, in process step P4, the controller 238 instructs that a third portion 240 of the base load power generated by the backup GT system 210R and generator 212 be sent to grid 204. Furthermore, the compressor 242 may be turned off if it is not already turned off. In at least one embodiment, the third portion 240 of the base load power of the backup GT system 210R used to power grid 204 is equivalent to the second portion 246 of the base load power of the backup GT system 210R used to power the compressor 242, although this is not necessary in all cases. In this way, the increase in power demand sufficient to require additional power from power plant 202 is met by the backup GT system 210R.

[0060] In any process steps P5 and P6 following process steps P3 and P4, one or more overall GT controllers 216 and / or controllers 238 may adjust at least the fuel flow rate of the supplemental GT system 250 in response to the preceding process step to maintain the output of the supplemental GT system 250. For example, with respect to process step P5, the supplemental GT system 250 may be adjusted in response to sending a second portion 246 of the base load power generated by the auxiliary GT system 210R to the compressor 242. Here, when the flow of auxiliary compressed air 244 to one or more supplemental GT systems 250 is initiated (P3), the output of one or more supplemental GT systems 250 may increase.

[0061] Alternatively, with respect to process step P6, the supplemental GT system 250 may be adjusted in response to sending a third portion 240 of the base load power generated by the auxiliary GT system 210R to the grid 204. If the flow of auxiliary compressed air 244 to one or more supplemental GT systems 250 is stopped (P4), the output of one or more supplemental GT systems 250 may decrease. To maintain output, at least the fuel flow rate of the supplemental GT systems 250 may be adjusted. In some cases, the fuel flow rate may be increased to increase output and compensate for the output loss due to the stoppage of supplemental compressed air 244. In other cases, the fuel flow rate may be decreased to decrease output and compensate for the additional output from the addition of auxiliary compressed air 244. Other operating parameters of the supplemental GT systems 250 may also be adjusted to maintain output, such as inlet vane location, fuel type, fuel composition, and staged fuel injection operation.

[0062] In certain embodiments, the flowchart in Figure 6 can be controlled by the power plant 202 without intervention from or knowledge of the TSO239. Alternatively, it can be controlled by the TSO239.

[0063] Furthermore, with respect to generators 212, 214, although each GT system 210R, 220 is shown to include its own generator, it will be recognized that GT systems 210R, 220 may share a generator. Thus, at least one of the generators 212, 214 used for the auxiliary GT system 210R, one or more primary GT systems 220, and one or more supplementary GT systems 250 may be the same generator. In the embodiment of Figure 2, the second portion 246 of the base load power generated by the auxiliary GT system 210R is sent directly to the compressor 242 to produce compressed air 244 for one or more supplementary GT systems 250 without passing through the grid 204. That is, the second portion 246 is maintained within the power plant 202. Here again, the transmission of the second portion 246 may be controlled by the power plant 202 or TSO 239.

[0064] Figure 7 shows a schematic diagram of system 200 according to another embodiment of the present disclosure. Here, a backup GT system 210R is operably coupled to a generator 212 to generate base load power, and all of the base load power is sent to the grid 204. That is, rather than dividing the base load power (as in Figure 2, which has a first part 237, a second part 246, and a third part 240), all of the base load power 260 generated by the backup GT system 210R and the generator 212 is sent to the grid 204. Here, a compressor 242 is configured to be selectively powered by power 262 from the grid 204. The compressor 242 is operably coupled to supply compressed air to one or more supplemental GT systems 250, and one or more supplemental GT systems 250 are operably coupled to one or more generators 214 to generate power for, for example, the grid 204 or another load. To supply power to the compressor 242 when needed, power 262 from the grid 204 is transmitted / returned to the compressor 242 to produce compressed air 244 for one or more supplemental GT systems 250. In this example, the controller 238 may be located in the TSO 239 of the grid 204. Here, the controller 238 may be part of a currently known or later developed AGC system, a separate system that works in conjunction with the AGC system, or it may be manually controlled. In any case, the TSO 239 can control the use of the compressor 242 without interacting with other control systems of the power plant 202 (e.g., controller 216).

[0065] Figure 8 shows a flowchart of how the system 200, more specifically the controller 238, is operated according to another embodiment of the present disclosure. Referring to Figures 7 and 8, in process step P10, the backup GT system 210R is operated at base load. According to embodiments of the present disclosure, the backup GT system 210R is always operated at base load, thus eliminating the inefficiencies caused by supplying spinning backup. In process step P10, the base load power 260 generated by the backup GT system 210R coupled to the generator 212 is sent to the grid 204. Also in process step P10, base load power (arrows omitted for clarity) generated by multiple primary GT systems 220 and operably coupled to one or more generators 214 is sent to the grid 204. As shown in Figure 2, the primary GT systems 220 may be located in the same place as the backup GT system 210R, but this is not required in all cases.

[0066] In process step P12, the controller 238 determines whether excess power from grid 204 exceeds a threshold, i.e., whether the total power generated by one or more power plants 202 exceeds the demand from grid 204 and is greater than the threshold. The threshold can be a currently known or later developed value that indicates that excess power from grid 204 is available. The threshold can be created, for example, as part of any currently known or later developed AGC algorithm to indicate that excess power is available and trigger a call to reduce the power generated by one or more power plants 202, for example. Such algorithms are well known and therefore require no further explanation.

[0067] Alternatively, the threshold can be manually determined, and the controller 238 can be activated by the TSO239. If the answer in process step P12 is "YES", it indicates that sufficient excess power from grid 204 for compressor 242(s) is available. In this case, in process step P13, the controller 238 increases (instructs) the power 262 from grid 204 to the compressor 242 in order to increase the amount of compressed air produced for the supplemental GT system 250. Here, compressors 242 that are already running can increase their output, and / or more compressors 242 that were not already running can be turned on. If the compressor 242 was not running, process step P13 starts the compressor 242 to begin supplying compressed air to the supplemental GT system 250. (The power 262 can be considered a return of some of the base load power 260 produced by the auxiliary GT system 210R).

[0068] As described above, the compressor 242 is operably coupled to supply compressed air 244 to one or more supplemental GT systems 250, and one or more supplemental GT systems 250 are operably coupled to generators 212, 214 to generate power. Power from one or more supplemental GT systems 250 may be used for the grid 204 or for other purposes. Compressed air 244 may be directed to one or more supplemental GT systems 250. As described above, using supplemental compressed air 244 with one or more supplemental GT systems 250 can improve the efficiency and performance of those one or more GT systems beyond what is possible with the compressed air supplied by each axial compressor 222 (Figure 3). In this way, the base load power 260 of the auxiliary GT system 210R is used to its maximum extent, and the power 262 is used to improve the efficiency and performance of one or more supplemental GT systems 250, and by extension, the efficiency and performance of the power plant 202. Any additional power generated by the power plant 202 having the compressor 242 can be used, for example, to reduce power generation at other locations that are not generated as efficiently as the power plant 202 having the compressor 242.

[0069] In Figure 7, as indicated by the solid arrow representing compressed air 244, the supplemental GT system 250 may be at least one of a plurality of primary GT systems 220. Alternatively, as described above, in other embodiments indicated by the solid and dashed line arrows, the supplemental GT system 250 may optionally be any number of primary GT systems 220 and / or auxiliary GT systems 210R.

[0070] Continuing with the flowchart in Figure 8, if the result in process step P12 is "NO", it indicates that the excess power from grid 204 is not greater than the threshold, for example, there is no overall excess power, or the power 262 from grid 204 is insufficient to power one or more compressors 242. In this case, in process step P14, the controller 238 reduces (instructs) the power from grid 204 to one or more compressors 242 in order to reduce the amount of compressed air produced for one or more supplemental GT systems 250. Here, any compressors 242 already in operation may have their output reduced, and / or at least some compressors 242 may be turned off. If insufficient excess power is available, as can be identified by the excess power not exceeding the threshold, process step P14 may turn off all compressors 242.

[0071] In any process steps P15 and P16 following process steps P13 and P14, one or more overall GT controllers 216 and / or controllers 238 may adjust at least the fuel flow rate of the supplemental GT system 250 to maintain the output of the supplemental GT system 250 in response to the preceding process. For example, with respect to process step P15, the supplemental GT system 250 may be adjusted in response to power 262 being supplied from the grid 204 to the compressor 242. Here, when the flow of supplemental compressed air 244 to one or more supplemental GT systems 250 begins (P13), the output of one or more supplemental GT systems 250 may increase.

[0072] Alternatively, with respect to process step P16, the supplemental GT system 250 may be adjusted in response to a decrease or cessation of power 262 from grid 204 to compressor 242. Here, if the flow of supplemental compressed air 244 to one or more supplemental GT systems 250 is stopped (P14), the output of one or more supplemental GT systems 250 may decrease. To maintain output, at least the fuel flow rate of one or more supplemental GT systems 250 may be adjusted, i.e., the output may be increased to compensate for the output loss due to the cessation of supplemental compressed air 244, or the output may be decreased to compensate for the additional output due to the addition of supplemental compressed air 244. Other operating parameters of the supplemental GT system 250 may also be adjusted to maintain output, such as inlet vane position, fuel type, fuel composition, and stepwise fuel injection operation.

[0073] The flowchart in Figure 8 shows that the TSO239 can be controlled without intervention from power plant 202, or it can be controlled by power plant 202.

[0074] Figure 9 is a schematic diagram of a system 200 according to an additional embodiment of the present disclosure. The system 200 in Figure 9 may follow the operational methodology of Figure 8. Here, any number of power plants 202A-C may operate all GT systems 210R, 220 at base load. That is, a backup GT system 210R may be operably coupled to one or more generators 212 to generate base load power to be sent to the grid 204. Also, multiple primary GT systems 220 may be co-located with their respective backup GT systems 210R, which are operably coupled to generators 214 to generate base load power to be sent to the grid 204. Thus, the collective base load power 268 of all GT systems is sent to the grid 204.

[0075] In these embodiments, one or more compressors 242A-C are not necessarily located together with the power plants 202A-C, but may be located wherever compressed air is needed, i.e., at sites 270A-C. In the illustrated non-limiting example, one compressor 242A can supply compressed air 244 to a supplemental GT system 250 at site 270A. Site 270A is different from the power plants 202A-C, and therefore the compressor 242 and the supplemental GT system 250 are located at a different geographical location from one or more auxiliary GT systems 210R. Here, the compressor 242A may be configured to be selectively powered by power from the grid 204. The compressor 242A is operably coupled to supply compressed air 244 to the supplemental GT system 250, which is operably coupled to one or more generators 214 to generate power. The supplemental GT system 250 may be, for example, a GT system that is not performing as expected and requires additional compressed air. The supplemental GT system 250 can be located at one or more geographical locations 270A that are different from one or more power plants 202A-C.

[0076] Other compressors 242B-C located at other sites 270B-C can supply compressed air 244 to any other variety of industrial applications 272 that require compressed air, such as aerospace, transportation, chemical manufacturing, electronics, food and beverage, general manufacturing, glassmaking, hospital / medical, mining, agriculture, construction, pharmaceuticals, plastics, or wood products, but are not limited to these. Any number of compressors 242 can be powered from grid 204, for example, through control by TSO 239 or other entities. Controller 238 may be configured to instruct power transmission from grid 204 to one or more compressors 242A-C, for example, to produce compressed air 244 for a supplemental GT system 250 at site 270A. This instruction may occur in response to excess power from grid 204 exceeding a threshold ("YES" in process steps P13 and P12 in Figure 8). Alternatively, the controller 238 may instruct the cessation of power transmission from grid 204 to one or more compressors 242A-C in response to the excess power from grid 204 not exceeding a threshold (process step P14, and "NO" in process step P12 in Figure 8). Process step P15 in Figure 8 may also be performed in system 200 in Figure 9.

[0077] In Figure 9, the controller 238 may be located in the TSO 239 of grid 204. Here again, the controller 239 may be part of any currently known or future AGC system, a separate system operating in conjunction with the AGC system, or manually controlled. In this example, the TSO 239 can control the use of the compressor 242 without interaction with other control systems in power plants 202A-C.

[0078] Embodiments of this disclosure provide a system in which one or more auxiliary GT systems are always operated at base load and, during periods of low power demand, excess base load power not required by the grid is used to power one or more electric compressors. Compressed air from one or more compressors can be injected into one or more additional supplemental GT systems to improve the performance of those GT systems. This method improves the overall performance of the power plant in which it is used by reducing fuel consumption, improving combustion temperature stability, extending the lifespan of one or more auxiliary GT systems and one or more supplemental GT systems (reducing maintenance), and reducing emissions. When grid power demand increases, the system reduces the power to the compressors (turn down or turn off) and sends power from the auxiliary GT systems to the grid to maintain grid stability.

[0079] The aforementioned drawings illustrate some of the processes relating to some embodiments of the present disclosure. In this regard, each drawing or block in the flowchart of the drawings represents a process step relating to an embodiment of the described method. It should also be noted that in some alternative embodiments, the actions shown in the drawings or blocks may occur in a different order than shown in the drawings, or may actually be performed substantially simultaneously or in reverse order, for example, depending on the actions involved. Furthermore, those skilled in the art will recognize that additional blocks describing processes may be added.

[0080] The approximate expressions used throughout this specification and the claims may be applied to modify any quantitative expression that may change acceptablely without altering the fundamental function of the expression in question. Thus, values ​​modified by terms such as “about,” “approximately,” and “substantially” are not limited to the exact values ​​specified. In at least some examples, approximate expressions may correspond to the precision of the instrument used to measure the value. Throughout this specification and the claims, range limitations may be combined and / or replaced. Such ranges, unless otherwise specified in context or wording, include all subranges contained therein. “About” applied to specific values ​​within a range may indicate ±10% of the stated value, unless it applies to both endpoints and depends on the precision of the instrument used to measure the value.

[0081] All corresponding structures, materials, actions, and equivalents of all means-plus-function elements or step-plus-function elements in the following claims are intended to include any structures, materials, or actions for performing a function in combination with other claimed elements, as specifically claimed. The descriptions in this disclosure are presented for illustrative and explanatory purposes and are not intended to be exhaustive or restrictive of the disclosure in the disclosed form. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments have been selected and described to best illustrate the principles and practical applications of this disclosure and to enable those skilled in the art to understand this disclosure in various embodiments with various modifications to suit a particular intended use. [Explanation of Symbols]

[0082] 100: Power plant 102: Wide-area power grid 110: GT system 114: Generator 200: System 202: Power plant 204: Grid 210: GT system 212, 214: Generator 216: GT controller 220: Additional GT system 222: Compressor 223: Governor 224: Turbine 226: Combustor 228: Shaft 230: Compressor rotor blade 232: Compressor stator blade 234: Turbine stator blade 236: Turbine rotor blade 237: First part 238: Controller 239: TSO 240: Third part 242: Compressor 244: Compressed air 246: Second part 250: Supplementary GT system 260: Base load power 262: Power 268: Base load power 270: Geographic location 272: Industrial application

Claims

1. A first gas turbine (GT) system (210R) operably connected to a first generator (114) to generate base load power (260), wherein a first portion (237) of the base load power (260) generated by the first GT system (110) is transmitted to a power grid (102) controlled by a transmission system operator (TSO) (239), A second gas turbine (GT) system (220) is operationally connected to a second generator (214) and generates power to supply primary base load power (260) to the power grid (204) with little surplus capacity other than the primary control reserve, A compressor (242) configured to be selectively powered by a second portion (246) of base load power (260) generated by a first GT system (210R), and operably connected to supply compressed air (244) to a second GT system (220), In response to a power demand (262) from a TSO (239) that does not exceed a threshold, a second portion (246) of the base load power (260) generated by the first GT system (210R) is instructed to be sent to the compressor (242) to generate compressed air (244) for the second GT system (220). A controller (238) is configured to instruct the compressor (222) to turn off in response to the power demand (262) from the TSO (239) exceeding a threshold, and to instruct the third portion (240) of the base load power (260) generated by the first GT system (210R) to be transmitted to the power grid (102), A system including (200).

2. The system (200) according to claim 1, further comprising a plurality of third gas turbine (GT) systems (250) located in the same position as the first GT system (210R), each third GT system (250) being operably connected to a third generator (214) that generates base load power (260) for transmission to a power grid (102).

3. The system (200) according to claim 2, wherein the second GT system (220) is at least one of a plurality of third GT systems (250).

4. The system (200) according to claim 3, wherein at least two of the first, second, and third generators (112, 212, 214) are the same generator.

5. The system (200) according to claim 2, wherein the compressor (222) and the second GT system (220) are located at different geographical locations from the first GT system (210R).

6. The system (200) according to claim 1, wherein a fourth portion of the base load power (260) generated by the first GT system (210R) is maintained as a primary control reserve by the governor (223) of the first GT system (210R).

7. The system (200) according to claim 1, wherein a second portion (246) of the base load power (260) generated by the first GT system (210R) is sent directly to a compressor (222) to generate compressed air (244) for the second GT system (220) without passing through the power grid (204).

8. The system (200) according to claim 1, wherein the controller (238) is installed in the TSO of the power grid (204).

9. The system (200) according to claim 8, wherein a third portion (240) of the base load power (260) generated by the first GT system (210R) is transmitted to a power grid (204), and power from the power grid (204) is transmitted to a compressor (222) to generate compressed air (244) for the second GT system (220).

10. The system (200) according to claim 1, in response to a controller (238) instructing the power grid (204) to send a third portion (240) of the base load power (260) generated by the first GT system (210R), the controller (238) adjusts at least the fuel flow rate of the second GT system (220) to maintain the output of the second GT system (220).

11. A first gas turbine (GT) system (210R) operably connected to a first generator (212) to generate base load power (260), the base load power (260) being transmitted to a power grid (204) controlled by a transmission system operator (TSO) (239), and A second gas turbine (GT) system (220) is operationally connected to a second generator (214) and generates power to supply primary base load power (260) to the power grid (204) and generates power to transmit to the power grid (204), A compressor (222) configured to be selectively powered by power from a power grid (204), the compressor (222) being operably coupled to supply compressed air (244) to a second GT system (220), In response to excess power from the power grid (204) exceeding a threshold, the power from the power grid (204) to the compressor (222) is increased to increase the amount of compressed air (244) produced for the second GT system (220). A controller (238) is configured to reduce the power from the power grid (204) to the compressor (222) in response to the excess power from the power grid (204) not exceeding a threshold, thereby reducing the amount of compressed air (244) produced for the second GT system (220), Includes, In response to the controller (238) reducing the power supplied to the compressor (222) from the power grid (204), the controller (238) adjusts at least the fuel flow rate of the second GT system (220) to maintain the output of the second GT system (200).

12. The system (200) according to claim 11, further comprising a plurality of third G gas turbine (GT) systems (250) located in the same position as the first GT system (210R), each third GT system (250) being operably connected to a third generator (214) that generates base load power (260) for transmission to the power grid.

13. The system (200) according to claim 12, wherein the second GT system (220) is at least one of a plurality of third GT systems (250).

14. The system (200) according to claim 11, wherein the compressor (222) and the second GT system (220) are located at different geographical locations from the first GT system (210R).

15. The system (200) according to claim 11, wherein the controller (238) is located at a power transmission service provider (TSO) (239) of the power grid (204).

16. The steps include transmitting a first portion (237) of base-load power (260) generated by a first gas turbine (GT) system (210R) connected to a first generator (212) to a power grid (204) controlled by a transmission system operator (TSO) (239), The steps of sending a second portion (246) of base-load power (260) generated by a first GT system (210R) to a compressor (222) in response to a power demand from a TSO (239) that does not exceed a threshold, wherein the compressor (222) is operably coupled to supply compressed air (244) to a second gas turbine (GT) system (220), and the second GT system (220) is operably coupled to a second generator to generate power, In response to the power demand from the TSO (239) exceeding a threshold, the compressor (222) is turned off, and a third portion (240) of the base load power (260) generated by the first GT system (210R) is transmitted to the power grid (204). Methods that include...

17. The method according to claim 16, further comprising the step of transmitting base load power (260) generated by a plurality of third gas turbine (GT) systems (250) operably coupled to a third generator (214) to a power grid (204), wherein the plurality of third GT systems (250) are located in the same positions as a first GT system (210R), and the second GT system (220) is at least one of the plurality of third GT systems (250).

18. The method according to claim 16, wherein the compressor (222) and the second GT system (220) are located at different geographical locations from the first GT system (210R).

19. The method according to claim 16, wherein at least the fuel flow rate of the second GT system (220) is adjusted in order to maintain the output of the second GT system (220) in response to sending a third portion (240) of the base load power (260) generated by the first GT system (210R) to the power grid (204).

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