Gas turbine with thermal energy storage system

Abstract

A gas turbine generator system is configured to be electrically interconnected to an electrical grid via a first circuit breaker. The gas turbine generator system includes a compressor configured to output a pressurized gas stream to an electrically heated thermal energy storage system that outputs a heated and pressurized gas stream to a gas turbine to rotate the gas turbine and drive a generator. The generator outputs electrical power to the electrical grid via the first circuit breaker that operates in a normally closed position. A controller is present to detect an opening of the first circuit breaker and to close a first switch in response to the opening of the first circuit breaker. The first switch is connected to an output of the generator and to an electrical input of the electrically heated thermal energy storage system, thereby connecting the generator to the thermal energy storage system.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 516,986, filed August 1, 2023, the disclosure of which is incorporated herein by reference in its entirety. This application also incorporates, by reference in its entirety, each of the following related and commonly owned provisional and non-provisional applications filed on the same date as this application: Chromium Electrodes to Deliver Electric Power to Oxide Brick Circuits, U.S. Application No. Application No. [Number]; Electrically Conductive Brickwork Module for Use as a Heating and / or Thermal Storage System, U.S. Application No. [Number]. Application No. [Number]; Ceramic-Metal Composites for Use as Heating Elements for Electrified Resistance Heating and Thermal Energy Storage Systems, US Application No. [Number] Application No. ; Electrically Conductive Brickwork Assembly for Use as a Heating and / or Thermal Storage System, U.S. Application No. Application No. [Number]; Modulating Electrical Resistance along a Column of E-Bricks, U.S. Provisional Application No. [Number] No. ; and Bent Pipe-Shaped Electrically Conductive Cross Brick Design, U.S. Provisional Application No. ; Number. Technical Field

[0002] This disclosure relates to a gas turbine system using a thermal energy storage system, and more specifically to such a gas turbine system using a thermal energy storage system to drive a turbine and provide overspeed protection. Background Technology

[0003] The internal combustion (gas) turbines installed in many of today's natural gas-fired power plants are complex machines comprising three main components: a compressor, a combustion system, and a turbine. The compressor draws air into the system, pressurizes it, and supplies it to the combustion system at speeds of hundreds of miles per hour. The combustion system typically consists of fuel injector rings that inject a steady stream of fuel (i.e., natural gas) into the combustion chamber, where it mixes with air. When an electric spark ignites the mixture, it burns at temperatures exceeding 2000 degrees Fahrenheit. The combustion system produces a high-temperature, high-pressure gas flow that enters the turbine and expands. The blades rotate at high speed and compress or squeeze the air, which in turn drives the generator to produce electricity that can be fed into the grid.

[0004] Another type of turbine is the steam turbine, which uses the expansion of high-pressure steam to generate rotational motion, while gas turbines rely on the combustion of fuel and air to drive hot gas at high speeds through the turbine. Yet another type of combustion turbine is the external combustion turbine, in which combustion occurs outside the turbine, unlike the internal combustion turbine where combustion occurs inside. External combustion turbines using pulverized coal and finely ground biomass as fuel have already been realized.

[0005] For any of the aforementioned turbines, a complete loss of generator electrical load can cause the turbine's operating speed to change catastrophically within seconds. The electrical load can be lost due to generator failure or grid outages caused by external factors such as hurricanes, floods, or ice storms damaging transmission lines. Overspeed occurs when the turbine's rotational speed exceeds its design limits. The consequences of an overspeed event vary depending on the machine's model and type, the duration of the overspeed, and the extent to which it exceeds design limits.

[0006] Current turbine overspeed protection includes mechanical and / or electrical tripping mechanisms designed to prevent damage to the system, such as sensors that detect unsafe conditions and correct turbine speed or shut down the turbine. However, these methods may not be sufficient to protect equipment and / or personnel. Summary of the Invention

[0007] According to one embodiment of the present invention, a gas turbine generator system is provided, configured to be electrically interconnected to a power grid via a first circuit breaker. It includes a compressor and an electrically heated thermal energy storage system, the compressor being configured to compress received gas and output a pressurized gas stream. The electrically heated thermal energy storage system is configured to receive the pressurized gas stream from the compressor at a fluid inlet, heat the pressurized gas stream, and output the heated and pressurized gas stream from a fluid outlet. A gas turbine is configured to receive the heated and pressurized gas stream from the fluid outlet of the electrically heated thermal energy storage system to rotate the gas turbine and drive a generator. The generator outputs electricity to the power grid via the first circuit breaker, which operates in a normally closed position. A controller is configured to detect the opening of the first circuit breaker, thereby disconnecting the generator from the power grid. The controller is configured to operate in an overspeed protection mode, wherein the controller closes a first switch in response to the opening of the first circuit breaker; wherein the first switch is connected to the generator output and to the electrical input of the electrically heated thermal energy storage system, thereby electrically connecting the generator to the electrical input of the electrically heated thermal energy storage system.

[0008] In other embodiments, one or more of the following features may be included: The electrically heated thermal energy storage system may include a plurality of conductive bricks that generate heat due to electrical application at an electrical input. The electrically heated thermal energy storage system may include a plurality of electrically insulating bricks that electrically insulate the plurality of conductive bricks, and the electrically heated thermal energy storage system may include a plurality of flow paths from a fluid input to a fluid output to guide pressurized airflow through the electrically heated thermal energy storage system and heat the pressurized airflow. The pressurized airflow may be heated to between 1000 degrees Celsius and 1700 degrees Celsius. A second switch may be provided between the generator and a first circuit breaker, and the first switch may be connected at a first end between the second switch and the first circuit breaker, and at a second end to the electrical input to the electrically heated thermal energy storage system. A first valve may be provided located between the compressor output and the fluid input of the electrically heated thermal energy storage system. A second valve may be provided located between the compressor output and the input of a third valve, and the third valve may have an output connected to the external environment. The controller may be configured to control the gas turbine generator system in thermal charge mode. In thermal storage mode, the controller can open the first valve to disconnect the compressor from the fluid input of the electric heating thermal energy storage system and can also shut down the compressor. The controller can open the second switch to disconnect the generator from the power grid and can close the first switch to connect the power grid to the electrical input of the electric heating thermal energy storage system to heat the system. The controller can be configured to control the gas turbine generator system in grid power mode, causing the first valve to close to connect the compressor to the fluid input of the electric heating thermal energy storage system and activating the compressor. The controller can close the second switch to connect the generator to the power grid and can also open the first switch to disconnect the electrical input of the electric heating thermal energy storage system from the power grid. The controller can be configured to control the gas turbine generator system in overspeed protection mode. In overspeed protection mode, the controller can also open the first valve to disconnect the compressor from the fluid input of the electric heating thermal energy storage system. The controller can shut down the compressor, turbine, and generator and can open the second switch to disconnect the generator from the electrical input of the electric heating thermal energy storage system.

[0009] According to another embodiment of the present invention, a method is provided for connecting a gas turbine generator system to a power grid via a first circuit breaker, the method comprising compressing received gas using a compressor and outputting a pressurized gas flow. The method includes receiving the pressurized gas flow at a fluid inlet of an electrically heated thermal energy storage system, heating the pressurized gas flow, and outputting the heated and pressurized gas flow from a fluid outlet of the electrically heated thermal energy storage system. The method includes receiving the heated and pressurized gas flow from the fluid outlet of the electrically heated thermal energy storage system by a gas turbine to rotate the gas turbine and drive a generator, the generator outputting electricity to the power grid via the first circuit breaker, the first circuit breaker being normally closed. Upon detection of the opening of the first circuit breaker, the method includes disconnecting the generator from the power grid and operating the gas turbine generator system in an overspeed protection mode. Operating the gas turbine generator system in overspeed protection mode includes closing a first switch in response to the opening of the first circuit breaker; wherein the first switch is connected to the output of the generator and to the electrical input of the electrically heated thermal energy storage system, thereby electrically connecting the generator to the electrical input of the electrically heated thermal energy storage system.

[0010] In further embodiments, one or more of the following features may be included: The electrically heated thermal energy storage system may include a plurality of conductive bricks that generate heat due to electrical application at an electrical input. The electrically heated thermal energy storage system may include a plurality of electrically insulating bricks that electrically insulate the plurality of conductive bricks. The electrically heated thermal energy storage system may include a plurality of flow paths from a fluid input to a fluid output to guide a pressurized airflow through the electrically heated thermal energy storage system and heat the pressurized airflow. The pressurized airflow may be heated to between 1000 degrees Celsius and 1700 degrees Celsius. The method may further include providing a second switch between a generator and a first circuit breaker, connecting the first switch at a first end between the second switch and the first circuit breaker, and connecting the first switch at a second end to the electrical input of the electrically heated thermal energy storage system. The method may further include providing a first valve between the compressor output and the fluid input of the electrically heated thermal energy storage system, and providing a second valve and a third valve, the second valve being positioned between the compressor output and the input of the third valve, the third valve having an output connected to the external environment. The method may further include controlling the gas turbine generator system to operate in a thermal storage mode, including: opening a first valve to disconnect the compressor from the fluid input of the electrically heated thermal energy storage system, shutting down the compressor, opening a second switch to disconnect the generator from the power grid, and closing the first switch to connect the power grid to the electrical input of the electrically heated thermal energy storage system to heat the system. The method may also include controlling the gas turbine generator system to operate in a grid-powered mode, including: closing the first valve to connect the compressor to the fluid input of the electrically heated thermal energy storage system, activating the compressor, closing the second switch to connect the generator to the power grid, and opening the first switch to disconnect the electrical input of the electrically heated thermal energy storage system from the power grid. Operating the gas turbine generator system in an overspeed protection mode may further include: opening the first valve to disconnect the compressor from the fluid input of the electrically heated thermal energy storage system, shutting down the compressor, turbine, and generator, and opening the second switch to disconnect the generator from the electrical input of the electrically heated thermal energy storage system. Attached Figure Description

[0011] The foregoing features of the embodiments will be more readily understood with reference to the accompanying drawings and the following detailed description. In the drawings: Figure 1 A perspective view of an exemplary E-TESS system according to one aspect of this disclosure is provided.

[0012] Figure 2 Provided Figure 1 A cross-sectional view of an exemplary E-TESS system.

[0013] Figure 3 A perspective view of an exemplary conductive brick of an E-TESS system according to one aspect of this disclosure is provided.

[0014] Figure 4 A perspective view of an exemplary electrically insulating brick for an E-TESS system according to one aspect of this disclosure is provided.

[0015] Figure 5 A cross-sectional view of an exemplary E-TESS system according to one aspect of this disclosure is provided, depicting the circuitry of conductive bricks connected to the input and output electrodes.

[0016] Figure 6 A schematic diagram of an embodiment of a gas turbine generator system according to the present disclosure is provided.

[0017] Figure 7 Provided Figure 6 A flowchart illustrating the operation of a gas turbine generator system in thermal storage / thermal energy storage mode.

[0018] Figure 8 Provided Figure 6 A flowchart illustrating the operation of a gas turbine generator system in grid power mode.

[0019] Figure 9 Provided Figure 6 A flowchart illustrating the operation of a gas turbine generator system in overspeed protection mode. Detailed Implementation

[0020] This disclosure and its various features and advantageous details are explained more fully with reference to the non-limiting embodiments and examples described and / or illustrated in the accompanying drawings and detailed in the following description. The various aspects of the subject matter discussed in more detail below can be implemented in any of a variety of ways, as the subject matter is not limited to any particular implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.

[0021] Unless otherwise defined, used, or characterized herein, the terms used herein (including technical and scientific terms) should be interpreted as having meanings consistent with their accepted meanings in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein. The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit exemplary embodiments. As used herein, singular forms (such as “a” and “an”) are also intended to include plural forms unless the context indicates otherwise. Furthermore, the terms “comprising” and “including” indicate the presence of a said element or step, but do not exclude the presence or addition of one or more other elements or steps.

[0022] Gas turbines can experience overspeed conditions when they lose their load (typically the power grid). This disclosure allows for the redirection of electricity generated at the generator from the grid to an electrically heated thermal energy storage system (E-TESS) in the event of generator load loss (i.e., power loss from the grid). Typically, when the turbine is running and the generator is generating electricity, the switch / circuit breaker to the grid is closed. In the event that this circuit breaker suddenly opens, for example due to a fault condition in the grid, the system of this disclosure allows for the immediate closing of the circuit breaker or switch to the electrically heated E-TESS, and the delivery of electricity to the electrically heated E-TESS, which can readily absorb the power, until the gas turbine can be smoothly shut down. In prior art systems, overspeed protection includes mechanical and / or electrical tripping mechanisms, such as sensors and circuit breakers / switches, which detect unsafe conditions and correct the turbine speed or shut it down. However, the system may still be damaged due to the overspeed condition before correction or shutdown.

[0023] Besides serving as part of an overspeed protection system for gas turbines, E-TESS can also be used as a source of heated compressed gas to drive an external combustion gas turbine. In this case, the gas turbine can be an external combustion turbine. For external combustion turbines, combustion occurs outside the turbine; in this case, it occurs within the E-TESS, unlike in internal combustion gas turbines where combustion occurs internally. Therefore, the E-TESS system described in this paper is used to drive a turbine that rotates a generator to produce electricity and output it to the power grid.

[0024] An example of such an E-TESS is described in U.S. Patent No. 11,877,376, the entire contents of which are incorporated herein by reference. Another E-TESS is... Figures 1 to 5 This E-TESS is shown in the diagram and described below. It is described in more detail in co-owned provisional and non-provisional applications filed on the same date as this application, which are mentioned above in the cross-reference section of the relevant applications.

[0025] Before describing the gas turbine generator system according to this disclosure, an exemplary E-TESS that can be used in the gas turbine system described herein is described. It should be noted that any other suitable E-TESS can be used to drive the turbine and provide overspeed protection according to this disclosure, and the E-TESS described herein is merely an example of such a system.

[0026] The embodiments described herein may include or utilize conductive (and thermally conductive) bricks (“E-bricks”). E-bricks generate heat via direct resistance heating (DRH) when an electric current flows through them. E-bricks may be capable of reaching very high temperatures, such as 1000°C to 2000°C or higher, and reliably cycle on a daily basis within a predetermined temperature range (e.g., ~1000°C to ~1800°C). E-bricks may be stacked and arranged into large structures, thermal energy storage systems (“TESS”) (also known as electrically heated thermal energy storage systems E-TESS). Examples of E-bricks and E-TESS can be found in U.S. Patent No. 11,877,376, the contents of which are incorporated herein by reference in their entirety. Embodiments of E-TESS can be used, for example, in various industrial and chemical processes that generate and / or consume heat, such as furnaces, kilns, refineries, and power plants, thereby enabling these processes to significantly reduce or eliminate the combustion of fossil fuels.

[0027] Figure 1 An exemplary embodiment of an E-TESS module 100 is shown, which primarily comprises a large number of conductive and thermally conductive brick assemblies 102 (“E-brick assemblies”). The E-brick assemblies 102 may include... Figure 3 The conductive brick 300 (“E-brick”), which is housed in Figure 4 Within an electrically insulating (but thermally conductive) brick 400 (“I-brick”). In some embodiments, more than one E-brick may be accommodated within the I-brick, or multiple I-bricks may be combined to provide insulation for one or more E-bricks. Figure 1 and Figure 2 In the middle, only the I-brick of the E-brick assembly 102 is visible because the E-brick is housed within the internal area of ​​the I-brick, such as Figure 4 As shown and described below, when a voltage is applied across the E-TESS module 100, the E-bricks in each column are physically in contact with each other and physically connected to the E-bricks in adjacent columns to form a continuous circuit, thereby allowing current to flow through the circuit formed by the E-bricks.

[0028] When current flows through the continuous circuit of the E-brick, the E-TESS module 100 generates a large amount of heat energy. This heat energy can be stored in the E-brick / I-brick for a long period of time (e.g., up to 24 hours). The heat energy can be collected immediately or after it has been stored by flowing a fluid (e.g., a gas, such as air or CO2) through the E-TESS module 100. The heat energy in the E-brick is transferred to the I-brick, and the flow paths or channels between the columns of the E-brick assembly 102 (e.g.,...) Figure 2(As shown) allows fluid to flow through the E-TESS module 100. This application may subsequently refer to the fluid, gas, or air flowing through the flow path or channel of the E-TESS module 100; however, it should be noted that these terms are used interchangeably herein and are intended to have the same meaning. Furthermore, any suitable fluid (such as air or CO2) can be used to extract heat from the E-TESS module 100. Additionally, in Figure 1 In the middle, some bricks were removed from the view for easier observation.

[0029] Figure 2 A side view of an embodiment of the E-TESS module 100 is shown. The E-TESS module 100 includes a large number of E-brick assemblies 102 arranged in multiple adjacent columns, which are physically and electrically interconnected in a serpentine manner to form a continuous circuit. The E-brick assemblies 102 are largely conductive only in the vertical direction (i.e., along the length of the column) and electrically insulated from the outside in all other directions by means of I-bricks, such that when there is a potential difference between the columns of E-brick assemblies 102, for example when power of different phases is flowing through adjacent columns, the current (via the connected E-bricks) follows the serpentine circuit and no arcing occurs between the columns.

[0030] There are flow paths or channels 208 between the columns through which air can flow (in the direction of entry or exit from the paper) to extract or collect the heat energy generated by the E-brick for use in heat loads. By allowing air to flow through flow path 208, heat can be extracted from the E-TESS module 100 without having the air in direct contact with the E-brick. This is particularly useful because if the E-brick contains Cr2O3 and is directly exposed to flowing air, the Cr2O3 tends to volatilize, which over time erodes the electrical properties of the brick and also produces the toxic gas CrO3, which must be kept below specified levels and as low as possible.

[0031] Current can be supplied, for example, by connecting to the top left corner (from) Figure 2 From the perspective of the upper right corner, a cable (not shown) enters the E-TESS module 100 and exits the E-TESS module 100 via a cable (not shown) connected to the upper right corner. In addition to the E-brick assembly 102, there may be other bricks, such as the double-width brick 202, thin brick 204, and end-connecting brick 206 used in the E-TESS module 100.

[0032] The double-width brick 202 provides horizontal stability between columns of the E-brick assembly 102 and structural integrity of the E-TESS module 100. The double-width brick 202 is insulated so that current can flow vertically within a column but not across columns. The double-width brick 202 can be thinner than the E-brick assembly 102 (i.e., has a lower height) because it spans the gap 208 between columns and thus partially obstructs airflow through the gap 208. For example, the double-width brick 202 can be half the height of the E-brick assembly 102.

[0033] Thin brick 204, like E-brick assembly 102, is single-width but thinner, meaning it has a lower height than E-brick assembly 102. Thin brick 204 can, for example, be half the height of E-brick assembly 102. Thin brick 204 can be used in conjunction with double-width brick 202 such that the stacked height of the double-width brick 202 and thin brick 204 is equal to the height of E-brick assembly 102. Thin brick 204 can also be used instead of double-width brick 202 in cases where double-width brick 202 is undesirable in at least one column, but desirable in another column at that level, for example due to its airflow obstruction effect, to maintain a uniform horizontal height of the bricks.

[0034] End-connecting bricks 206 physically and electrically connect the columns of bricks together. End-connecting bricks 206 act as end caps for a column of bricks and house E-bricks therein. These E-bricks may have a different shape than those housed in E-brick assembly 102 to physically and electrically connect an E-brick from one column of E-brick assembly 102 to an adjacent column of E-brick assembly 102. For example, current can flow downwards through one column of bricks, making a "U-turn" through end-connecting bricks 206, then upwards through an adjacent column until reaching the next end-connecting brick 206 where it will make another "U-turn," and so on. End-connecting bricks may have channels or cutouts through which air can flow. End-connecting bricks 206 may typically have a flat bottom (or top, depending on its orientation).

[0035] Figure 3 A specific embodiment of the conductive brick 300 (“E-brick”) is shown. As described above, the E-bricks 300 can be configured to be stacked vertically on top of each other, which creates a portion of a conductive circuit through which current and heat can flow. The E-bricks 300 can be formed in many different shapes, including cross-sectional shapes such as circles, rectangles, squares, or crosses. Figure 3 An example of a "dog bone" shaped E-brick is shown. The E-brick 300 may have rounded corners or chamfered corners 302.

[0036] Also refer to Figure 4E-brick 300 is configured to be fitted within electrically insulating brick 400 (“I-brick”). I-brick 400 may have a hollow internal region 402 in which E-brick 300 can be fitted. E-brick assembly 102 may include E-brick 300 within I-brick 400. Based on the E-brick design, the external shape of I-brick and the shape of hollow internal region 402 may have different shapes. Other bricks may also include E-bricks within I-bricks. Hollow portion 402 may extend through the height of I-brick 400, allowing E-brick 300 to be electrically connected to E-bricks above and below.

[0037] Some I-brick embodiments may include multiple hollow sections, such as a double-length I-brick with two collinear hollow sections, each capable of accommodating an E-brick. The relative dimensions of the E-brick 300 and I-brick 400 allow for a gap of several millimeters between the outer side of the E-brick and the inner side of the I-brick's hollow section. For example, gaps of 1, 2, 5, 7, or 10 mm may exist. This gap allows for thermal expansion at different rates between the E-brick 300 and I-brick 400 due to material and temperature differences, and reduces frictional damage between the E-brick 300 and I-brick 400. The rounded corner 302 also helps reduce frictional damage. Other bricks may have hollow sections similar to the hollow section 402. The I-brick may include a pin hole 404 in which a pin or rod can be placed for aligning the stacking of bricks. The I-brick 400 may be made in different shapes in both its outer and inner hollow sections 402.

[0038] Figure 5 A cross-sectional view of an embodiment of the conductive brick masonry module 500 according to the present disclosure is shown. In this embodiment, an electrode 502, electrically connected by means of an external current source (not shown), passes through an insulating cover 504 into the conductive brick masonry module 500, thereby contacting the serpentine circuit of the E-brick 506. When current flows from the electrode 502 through the serpentine circuit, the E-brick 506 is resistively heated. The E-brick 506 transfers heat to the thermal I-brick 508, thereby providing an efficient thermal energy storage mechanism.

[0039] According to one aspect of this disclosure, an E-TESS can be used to drive a turbine to generate electricity for the power grid and provide overspeed protection. The turbine system may include a compressor configured to compress received gas and output a pressurized gas stream to the E-TESS. As described above, the E-TESS may include a plurality of conductive bricks that generate heat due to electrical application at an electrical input. In one case, the electrical input may be supplied from the power grid or another power source not shown. The E-TESS is configured to receive the pressurized gas stream from the compressor, heat the pressurized gas as it flows through the E-TESS system, and output a heated and pressurized gas stream.

[0040] When there is a large amount of stored energy in electrically heated thermal energy storage systems and high-pressure pipelines, turbine / generator overspeed is a serious problem after load shedding (i.e., disconnection from the grid). Conventional methods to prevent overspeed involve cutting off the energy source to the turbine (i.e., by shutting off, venting, or bypassing). However, this may be impractical if valves must be rated for very high temperatures and pressures (valves are primarily used for isolation rather than rapid action). Therefore, it is necessary to maintain a continuous load on the turbine system while shutting it down. This disclosure allows for a continuous load on the turbine / generator until the turbine system can be safely shut down by having the electrically heated thermal energy storage system act as the load.

[0041] Operating an electrical switch is much faster than opening / closing a mechanical valve, meaning that any overspeed will be minimal. Once electricity is directed to the electrically heated thermal energy storage system, the system can be smoothly shut down. This solution can be applied to any general-purpose gas turbine.

[0042] exist Figure 6 The present disclosure describes a gas turbine generator system 600 according to one aspect of the present disclosure. The gas turbine generator system 600 is configured to be electrically interconnected to a power grid 602 via a first circuit breaker 604 to supply power to the grid. The gas turbine generator system 600 includes a compressor 604 that compresses gas supplied from a storage tank 606, and when the system needs compressed gas to be heated by a TESS 610 to drive a turbine 612 via line 614 using the heated and compressed gas, a pressurized gas flow is output to the TESS 610 via a control valve 609 on line 608. When the turbine is driven, it rotates a shaft 615, which in turn rotates a generator 616 to generate electricity to be output to the power grid 602.

[0043] In grid power operation mode when generator 612 outputs power to grid 610, the first circuit breaker 604 operates in the closed state under the control of switch / circuit breaker controller 618, which is ultimately controlled by system controller 620. In grid power mode, switch / circuit breaker controller 618 closes switch 622 and opens switch 624. Therefore, the power output from generator 616 is output to grid 602.

[0044] Before the gas turbine generator system 600 can output power to the grid 602 and operate in grid power mode, the E-TESS 610 must store heat to heat the compressed gas from the compressor 604 to drive the turbine 612, which in turn drives the generator 616. In heat storage mode, the system controller instructs the switch controller to open switch 622 and close switch 624, allowing power from the grid 602 to be supplied to the E-TESS 510 via line 628 until it stores heat to its normal operating temperature between 1000 and 1700 degrees Celsius.

[0045] Using inputs from sensors in E-TESS 610, system controller 620 can switch from thermal storage mode to thermal energy storage mode when E-TESS is fully thermally stored, i.e., when it reaches its operating temperature. Thermal energy can be stored in E-TESS 610 for up to approximately twenty-four (24) hours when grid 602 does not require power from gas turbine generator system 600. It should be noted that gas turbine generator system 600 serves as a supplemental power supply to grid 602 and does not require continuous power supply. For example, it can be used to supply additional power to grid 602 during peak demand periods. In thermal energy storage mode, system controller instructs switch controller to hold switch 622 in the open position and open switch 624 so that power from grid 602 is not supplied to E-TESS 510 via line 628.

[0046] When the system switches from thermal storage or heat storage mode (after thermal energy has been stored for a period of time), and the power grid 602 requires supplemental power from the gas turbine generator system 600, the system controller 620 can switch to grid power mode and cause the switch / circuit breaker controller 618 to open (or remain open) switch 624 to stop supplying power to the E-TESS 610. After the turbine has been activated (described below) and is driving the generator 616 at the required voltage and frequency, the switch / circuit breaker controller 618 can close the generator switch 622. In power mode, the switch controller 618 also ensures that the circuit breaker 604 is closed (i.e., there is no fault condition on the power grid 602), so the generator 616 can be electrically connected to the power grid 602.

[0047] In addition to interfacing with the switch / circuit breaker controller 618, the system controller 620 can also communicate with the valve controller 626 to open the valve 609, and the system controller 620 can activate the compressor 604 so that compressed gas (typically in the range of 5 bar to 25 bar) can be fed to the E-TESS 610. The compressed gas is heated to an operating temperature between 1000 and 1700 degrees Celsius by the E-TESS 610, and the compressed and heated gas is fed to the input of the turbine 612 via line 614. The compressed and heated gas causes the turbine 612 to rotate, which in turn rotates the shaft 615 and drives the generator 616.

[0048] The system includes other valves under the control of valve controller 626. For example, when system 600 is in electric mode, valve 630 must be closed, so all gas from the compressor is directed to E-TESS 610 via line 608. When the system is not in electric mode, there may be residual gas in the system that needs to be discharged to ambient air. In this case, the valve controller closes valve 630 (but valve 609 is open) to discharge the residual gas. For various reasons, compressed gas may need to be deflected around E-TESS 610, so the valve controller can open valve 609 and close valve 634, thereby allowing compressed gas to bypass E-TESS 610. Valve 636 is also included, for example, to control the flow of ambient air into the compressor when the system needs to purge gas already supplied by gas storage tank 606.

[0049] When the gas turbine generator system 600 is outputting power to the grid 602 in grid power mode, the switch / circuit breaker controller 618 monitors the circuit breaker 604 to determine when it disconnects, thereby indicating a fault condition on the grid 602. When this occurs, the system switches to overspeed protection mode, and the switch / circuit breaker controller 618 closes switch 624 to direct the electrical output of generator 616 to E-TESS 610 via line 622. This immediately provides sufficient load to generator 616 to prevent it from entering an overspeed state. System controller 620 terminates the operation of compressor 604 and turbine 612, which in turn stops the rotation of generator 616 and electrical output. System controller 602 also instructs valve controller 626 to close valve 609 to prevent gas output from compressor 604 from being supplied to E-TESS 610, and it opens valves 630 and 632 to direct airflow from compressor 604 to ambient air output. It also opens valve 636 to prevent further intake of air from the ambient environment.

[0050] To absorb the output of generator 616 and prevent overspeed, the E-TESS 610 must be designed / sized to handle the generator output in terms of voltage, current, and power. It can be designed to provide at least a 10% margin; that is, for X MW of generator output, an E-TESS capable of handling 110% of X MW might be sufficient. In cases where the E-TESS also supplies compressed and heated gas to drive the turbine (as in the system described herein), the size of the E-TESS will not be an issue, as the E-TESS is somewhat inefficient, for example, at 50%. To enable the turbine / generator to output X MW to the grid, the E-TESS must be rated at approximately 2X MW. This rating makes the E-TESS highly capable of handling the generator output for overspeed protection.

[0051] It should be understood that a single circuit breaker or switch (in place of circuit breaker 604 and switch 624) can be used to disconnect the generator from the grid, or to connect the generator's output to the electric heating thermal energy storage system when the generator is disconnected from the grid. It should also be understood that a single system controller (i.e., system controller 620) can perform the functions of switch / circuit breaker controller 618 and valve controller 626.

[0052] refer to Figure 7 Flowchart 700 in the diagram depicts the operation of the gas turbine generator system 600 during thermal storage / heat storage mode. As described above, Figure 6 The E-TESS 610 must store heat to heat the compressed gas from the compressor 604 to drive the turbine 612, which in turn rotates the generator 616. When the system controller 620 determines that the E-TESS 610 must store heat, it enters the heat storage / storage mode at step 702 of flowchart 700 based on a low temperature sensed in the E-TESS 610. At step 704, the compressor 604 is disconnected from the E-TESS 610, the generator 616 is disconnected from the power grid 602 by opening switch 622, and switch 624 is closed to connect the electrical input of the E-TESS 610 to the power grid 602 via line 625.

[0053] Flowchart 700 proceeds to step 706, where the temperature of E-TESS 610 is checked, and if it has not yet reached its operating temperature, in step 708, the system keeps switch 624 closed to maintain the connection between the grid 602 and the electrical input of E-TESS 610. This cycle continues until the operating temperature of E-TESS 610 has been reached in step 706. When the operating temperature has been reached in step 710, switch 624 is opened to disconnect the electrical input of E-TESS 610 from the grid 602, and in step 712, the system enters thermal storage mode to store thermal energy in E-TESS 610 until it is needed to drive turbine 612 in grid mode. When E-TESS 610 is fully thermally stored, i.e., when it reaches its operating temperature, thermal energy can be stored in E-TESS 610 for up to approximately twenty-four (24) hours.

[0054] refer to Figure 8 Flowchart 800 in the flowchart depicts the operation of the gas turbine generator system 600 during grid power mode. When the E-TESS 610 is sufficiently heated and the grid 602 requires power from the gas turbine generator system 600, the system can enter grid power mode at step 802 in flowchart 800. In this mode, at step 804, the system controller 620 causes the switch / circuit breaker controller 618 to open (or remain open) switch 624 so as not to supply power to the E-TESS 610. At step 804, the system controller 620 also activates the compressor 604, turbine 612, and generator 616, and causes the compressor 604 to flow compressed air to the E-TESS 610 and through the E-TESS 610 to drive the turbine 612 and cause the generator 616 to rotate. At step 806, the generator 616 is driven to match the voltage and frequency required by the power grid 602, and at step 808, the switch / circuit breaker controller 618 closes the generator switch 622 to connect the generator 616 to the power grid and supply power to it.

[0055] At step 810, the temperature of E-TESS 610 is monitored, and it is determined whether a lower temperature threshold has been reached. If not, the system continues to operate in grid power mode at step 812. If the lower temperature threshold is reached at step 810, the system proceeds to step 814, where generator switch 622 is opened to disconnect from gas turbine generator system 600, thereby disconnecting it from the grid 602. At step 816, the compressor, turbine, and generator are shut down, and grid power mode is terminated.

[0056] refer to Figure 9Flowchart 900 in the flowchart depicts the operation of the gas turbine generator system 600 during overspeed protection mode. When the gas turbine generator system 600 is operating in grid power mode, the system controller 620 monitors the circuit breaker 604 to ensure it remains in the closed position, and the generator is supplying power to the grid 602. If the system controller 620 senses the opening of the circuit breaker 604 in response to a fault condition on the grid 602, the system is switched to overspeed protection mode in step 902 of flowchart 900. In step 904, the system controller 620 instructs the switch / circuit breaker controller to close switch 624, which causes the power output from the generator 616 to be routed through line 625 to the electrical input of the E-TESS 610, thereby preventing the generator 616 from entering an overspeed state, since the E-TESS 610 provides a sufficiently large electrical load.

[0057] When connected to E-TESS 610, the system initiates a shutdown process by safely disabling compressor 604, turbine 612, and generator 616, including releasing accumulated pressure in the system by opening control valves 630 and 632 via valve controller 626 to vent gas from the system to the external environment. After the system has been safely shut down, in step 908, switch / circuit breaker controller 618 disconnects switch 624 to disconnect E-TESS 610 from generator 616.

[0058] The embodiments of this disclosure described above are intended to be exemplary only; many variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to fall within the scope of this disclosure.

Claims

1. A gas turbine generator system configured to be electrically interconnected to a power grid via a first circuit breaker, the gas turbine generator system comprising: A compressor configured to compress received gas and output a pressurized gas flow; An electrically heated thermal energy storage system; wherein the electrically heated thermal energy storage system is configured to receive the pressurized airflow from the compressor at a fluid inlet, heat the pressurized airflow, and output the heated and pressurized airflow from a fluid outlet; A gas turbine configured to receive the heated and pressurized gas flow from the fluid output of the electrically heated thermal energy storage system to rotate the gas turbine and drive a generator, wherein the generator outputs power to the power grid via a first circuit breaker operating in a normally closed position; A controller configured to detect the opening of the first circuit breaker, thereby disconnecting the generator from the power grid; the controller is configured to operate in an overspeed protection mode, wherein the controller closes a first switch in response to the opening of the first circuit breaker; wherein the first switch is connected to the output of the generator and the electrical input of the electric heating thermal energy storage system, thereby electrically connecting the generator to the electrical input of the electric heating thermal energy storage system.

2. The gas turbine generator system according to claim 1, wherein, The electric heating thermal energy storage system includes multiple conductive bricks that generate heat due to the application of electricity at the electrical input.

3. The gas turbine generator system according to claim 2, wherein, The electric heating thermal energy storage system includes a plurality of electrically insulating bricks that electrically insulate the plurality of conductive bricks; and wherein the electric heating thermal energy storage system includes a plurality of flow paths from the fluid inlet to the fluid outlet to guide the pressurized airflow through the electric heating thermal energy storage system and heat the pressurized airflow.

4. The gas turbine generator system according to claim 3, wherein, The pressurized airflow is heated to between 1000 and 1700 degrees Celsius.

5. The gas turbine generator system according to claim 1, wherein, It includes a second switch between the generator and the first circuit breaker, wherein the first switch is connected at a first end between the second switch and the first circuit breaker, and the first switch is connected at a second end to the electrical input of the electric heating thermal energy storage system.

6. The gas turbine generator system according to claim 5, wherein, A first valve is included between the output of the compressor and the fluid input of the electric heating thermal energy storage system; and a second valve is included between the output of the compressor and the input of a third valve, the third valve having an output connected to the external environment.

7. The gas turbine generator system according to claim 6, wherein, The controller is configured to control the gas turbine generator system in a thermal storage mode; wherein, in the thermal storage mode, the controller a) opens the first valve to disconnect the compressor from the fluid input of the electric heating thermal energy storage system and disables the compressor, b) opens the second switch to disconnect the generator from the power grid, and c) closes the first switch to connect the power grid to the electrical input of the electric heating thermal energy storage system to heat the electric heating thermal energy storage system.

8. The gas turbine generator system according to claim 6, wherein, The controller is configured to control the gas turbine generator system in grid power mode; wherein, in grid power mode, the controller a) closes the first valve to connect the compressor to the fluid input of the electric heating thermal energy storage system and activates the compressor, b) closes the second switch to connect the generator to the grid, and c) opens the first switch to disconnect the electrical input of the electric heating thermal energy storage system from the grid.

9. The gas turbine generator system according to claim 6, wherein, The controller is configured to control the gas turbine generator system in an overspeed protection mode; wherein, in the overspeed protection mode, the controller further: a) opens the first valve to disconnect the compressor from the fluid input of the electric heating thermal energy storage system, b) disables the compressor, turbine, and generator, and c) disconnects the second switch to disconnect the generator from the electrical input of the electric heating thermal energy storage system.

10. A method for connecting a gas turbine generator system to a power grid via a first circuit breaker, the method comprising: The received gas is compressed using a compressor and a pressurized gas stream is output. The pressurized airflow is received at the fluid inlet of the electric heating thermal energy storage system, the pressurized airflow is heated, and the heated and pressurized airflow is output from the fluid outlet of the electric heating thermal energy storage system. The gas turbine receives the heated and pressurized gas flow from the fluid output of the electrically heated thermal energy storage system to rotate the gas turbine and drive a generator, which outputs power to the power grid via the first circuit breaker, which is in a normally closed position. When the first circuit breaker is detected to be open, the generator is disconnected from the power grid; Operating the gas turbine generator system in overspeed protection mode includes: closing a first switch in response to the opening of the first circuit breaker; wherein the first switch is connected to the output of the generator and the electrical input of the electric heating thermal energy storage system, thereby electrically connecting the generator to the electrical input of the electric heating thermal energy storage system.

11. The method according to claim 10, wherein, The electric heating thermal energy storage system includes multiple conductive bricks that generate heat due to the application of electricity at the electrical input.

12. The method according to claim 11, wherein, The electric heating thermal energy storage system includes a plurality of electrically insulating bricks that electrically insulate the plurality of conductive bricks; and wherein the electric heating thermal energy storage system includes a plurality of flow paths from the fluid inlet to the fluid outlet to guide the pressurized airflow through the electric heating thermal energy storage system and heat the pressurized airflow.

13. The method according to claim 12, wherein, The pressurized airflow is heated to between 1000 and 1700 degrees Celsius.

14. The method of claim 10, further comprising providing a second switch between the generator and the first circuit breaker, and connecting the first switch at a first end between the second switch and the first circuit breaker, and connecting the first switch at a second end to the electrical input of the electrically heated thermal energy storage system.

15. The method of claim 14, further comprising providing a first valve between the output of the compressor and the fluid input of the electrically heated thermal energy storage system; and providing a second valve and a third valve, the second valve being positioned between the output of the compressor and the input of the third valve, the third valve having an output connected to an external environment.

16. The method of claim 15, further comprising controlling the gas turbine generator system to operate in a thermal storage mode, including: The first valve is opened to disconnect the compressor from the fluid input of the electric heating thermal energy storage system, thereby stopping the compressor; the second switch is opened to disconnect the generator from the power grid; and the first switch is closed to connect the power grid to the electrical input of the electric heating thermal energy storage system to heat the electric heating thermal energy storage system.

17. The method of claim 15, further comprising controlling the gas turbine generator system to operate in grid power mode, including: The first valve is closed to connect the compressor to the fluid input of the electric heating thermal energy storage system, the compressor is activated, the second switch is closed to connect the generator to the power grid, and the first switch is opened to disconnect the electrical input of the electric heating thermal energy storage system from the power grid.

18. The method according to claim 15, wherein, Operating the gas turbine generator system in overspeed protection mode further includes: opening the first valve to disconnect the compressor from the fluid input of the electric heating thermal energy storage system, deactivating the compressor, turbine, and generator, and disconnecting the second switch to disconnect the generator from the electrical input of the electric heating thermal energy storage system.

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