Methods and systems for rapid load support in response to power grid frequency transient events

Abstract

This invention is entitled "Method and System for Rapid Load Support of Power Grid Frequency Transient Events". This application provides a method and system for rapid load support of power grid frequency transient events. An exemplary system may include: a turbine having a first controller; a generator coupled to the turbine, wherein the generator is configured to provide power to the power grid; and an exciter configured to provide a direct current (DC) voltage and a DC current to the rotor of the generator. The exciter may include a second controller configured to monitor a first set of electrical characteristics associated with the power grid, determine the presence of a transient event on the power grid based on the first set of electrical characteristics, and send a notification of the transient event to the first controller.

Description

Technical Field

[0001] This application and the resulting patents relate in general to gas turbine systems, and more specifically to providing rapid load support in response to transient events in the power grid frequency. Background Technology

[0002] Power plants or power generation systems can generate electricity using other primary energy sources. For example, a prime mover such as a gas turbine is a rotating mechanical device with a gas turbine shaft that drives a generator to supply electricity to a transmission grid. The transmission grid then supplies electricity to various electricity users. To ensure the efficient operation of the power generation system, the turbine shaft speed and the resulting grid frequency should be synchronized within their operating range. A sudden change in the grid frequency due to transient events can lead to power outages.

[0003] For smaller power grids, such as those providing approximately 500 megawatts (MW) of load capacity, the negative impacts of transient events, such as sudden changes in grid frequency, are amplified. Smaller grids are generally less stable than larger grids because the same amount of load change will result in a larger frequency change. Therefore, smaller grids tend to experience frequency changes more frequently than larger grids. This lack of stability can lead to grid outages and / or power losses. Therefore, systems and methods that provide rapid load support for grid frequency transient events are needed to enhance grid power stability. Summary of the Invention

[0004] This application and the resulting patent provide a system for providing rapid load support using a gas turbine. The system may include: a turbine having a first controller; a generator coupled to the turbine, wherein the generator is configured to provide power to a power grid; and an exciter configured to provide a direct current (DC) voltage and a DC current to the rotor of the generator. The exciter may include a second controller configured to monitor a first set of electrical characteristics associated with the power grid, determine, based on the first set of electrical characteristics, the presence of a transient event on the power grid, and send a notification of the transient event to the first controller. The first controller may be configured to regulate the operation of the turbine based on the notification.

[0005] This application and the resulting patent also provide a method for providing improved load support for grid frequency transient events. The method may include: monitoring a first set of electrical characteristics associated with the grid by a first controller; determining, based on the first set of electrical characteristics, that a transient event exists on the grid by the first controller; and sending a notification of the transient event to a second controller. The second controller may be configured to regulate turbine operation based on the notification by: (i) adjusting the dynamics of fuel demand to the turbine's fuel valve regulator; and (ii) adjusting the main frequency algorithm.

[0006] This application and the resulting patent also provide a system for providing rapid load support. The system may include: a prime mover, such as an aero-derivative gas turbine, having a first controller; a generator coupled to the aero-derivative gas turbine, wherein the generator is configured to supply power to the grid; and an exciter configured to supply direct current (DC) voltage and DC current to the rotor of the generator. The exciter may include a second controller configured to monitor a first set of electrical characteristics associated with the grid, determine the presence of a transient event on the grid based on the first set of electrical characteristics, and send a notification of the transient event to the first controller. The first controller may be configured to regulate the operation of the aero-derivative gas turbine based on the notification by: (i) regulating the dynamics of fuel demand on the fuel valve regulator of the aero-derivative gas turbine, and (ii) regulating the main frequency algorithm.

[0007] These and other features and improvements of this application and the resulting patent will become apparent to those skilled in the art upon reading the following detailed description in conjunction with the accompanying drawings and claims. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of a power generation system.

[0009] Figure 2 This is a schematic diagram of a control system for an exciter and a gas turbine, as may be described in this article.

[0010] Figure 3 This is an exemplary processing flow for providing rapid load support for grid frequency transient events, as may be described herein.

[0011] Figure 4 This is an exemplary processing flow for providing rapid load support for grid frequency transient events, as may be described herein. Detailed Implementation

[0012] Referring now to the accompanying drawings, in which similar numbers in several views refer to similar elements. Figure 1 This is a schematic diagram of a power generation system 100. The power generation system 100 may include a prime mover that generates electricity from other primary energy sources. An exemplary prime mover may be a gas turbine 150, such as an aero-derivative gas turbine, and may be a rotating mechanical device having a gas turbine shaft that drives a generator to supply electricity to a power grid that supplies electricity to users. Other embodiments may include different types of turbines, such as steam turbines. For trouble-free operation, the turbine shaft speed and the resulting grid frequency must be maintained within the operating range.

[0013] The gas turbine 150 can be connected to a generator 130 that supplies power to the power grid 140. The gas turbine engine 150 may include a compressor. The compressor compresses the incoming airflow. The compressor delivers the compressed airflow to a combustor. The combustor mixes the compressed airflow with a pressurized fuel flow and ignites the mixture, thereby producing a combustion gas flow. The combustion gas flow is then delivered to the turbine. The combustion gas flow drives the turbine to generate mechanical work. The mechanical work generated in the turbine drives the compressor via a shaft and drives an external load such as the generator 130.

[0014] The gas turbine engine 150 can use natural gas, various types of syngas, liquid fuels and / or other types of fuels and their blends. The gas turbine engine 150 can have different constructions and can use other types of components. Other types of gas turbine engines can also be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation devices can also be used together herein.

[0015] The gas turbine 150 can also be connected to a turbine controller 160. The turbine controller 160 can control the operation of one or more aspects of the gas turbine 150. The generator 130 can be connected to an exciter 120 controlled by an exciter controller 110. The exciter 120 can be configured to automatically regulate voltage and supply a direct current (DC) output. For example, the exciter 120 may include circuitry that provides DC current and DC voltage to the excitation windings of the rotor of the generator 130, thereby inducing a magnetic field within the generator 130. The magnetic field can then cause the rotor to rotate within the generator and cause the shaft of the generator 130 to rotate. In addition to generating a magnetic field within the generator 130, the exciter 120 can be used to control the frequency, amplitude, and phase characteristics of the voltage output by the generator 130. Thus, after the generator shaft has rotated at its rated speed, the exciter 120 can be used to synchronize the voltage output by the generator 130 with the voltage of the power grid 140.

[0016] The exciter controller 110 may optionally include one or more of an input interface 112, an output interface 118, one or more processors 114, and / or one or more memory devices 116. As detailed below, under the control of the power generation system 100, the exciter controller 110 facilitates the identification of transient grid events. In an alternative embodiment, a controller separate from the exciter controller 110 may be used to replace or assist the exciter controller 110.

[0017] Following a transient event on the power grid 140 that causes a frequency deviation, the power generation system 100 can use the turbine controller 160 to bring the system back to equilibrium. For example, when a frequency drop is detected in the power grid 140, a speed drop can be detected because speed varies with the grid frequency. The prime mover's fuel intake will increase based on the sensed speed drop, which increases active power output to compensate for the frequency drop.

[0018] The turbine 150 rotates the shaft in the generator 130, causing the generator 130 to output voltage. The voltage output of the generator 130 can then be synchronized with the voltage of the power grid 140. In some embodiments, the exciter controller 110 can monitor the electrical characteristics of the power grid 140. Therefore, the exciter controller 120 can monitor transient events of the power grid 140, such as increases or decreases in the grid frequency, increases or decreases in the active or reactive power of the generator 130, etc. Transient events may include changes in electrical characteristics such as voltage, current, power, power factor, etc.

[0019] In some implementations, the exciter controller 120 may be configured to detect or identify transient grid events in the initial phase of a grid transient. Upon detecting a transient event, the exciter controller 120 may send commands or notifications to the turbine controller 160 to regulate the operation of the prime mover and compensate for frequency variations in the generator. That is, the exciter controller 120 may monitor electrical parameters of the generator 130, such as power output and electrical frequency, and detect transient events based on these electrical parameters.

[0020] The power generation system 100 described herein can provide rapid load support in response to grid frequency transient events via one or a combination of the following: (i) early electrical detection of grid events; (ii) using MW modeling values ​​instead of measured wattmeter values ​​(e.g., avoiding reading the power component contributed by the generator's kinetic energy in response to frequency transients at the wattmeter); and / or (iii) using flexible dynamics for the fuel value control loop. Thus, turbine response acceleration can be achieved without oscillating the turbine frequency. Furthermore, in response to a decrease in grid frequency, instantaneous power can be provided using, for example, aero-derivative gas turbines.

[0021] Figure 2 This is a schematic diagram of a control system for an exciter and a gas turbine, as may be described herein. (Compared to...) Figure 2 Compared to those examples discussed, other implementations may have additional, fewer, and / or different components or constructions.

[0022] Figure 2 The control system shown can be used to provide rapid power in response to frequency events in small or potentially unstable power grids. Some implementations may use aero-derivative gas turbines with fuel sources such as diesel or ethanol.

[0023] exist Figure 2 In this system, the Automatic Voltage Regulator (AVR) / exciter controller 200 can be configured to control the operation of an exciter that supplies DC voltage and / or DC current to the rotor of a generator. The AVR / exciter controller 200 may include one or more early electrical detection modules 202. The early electrical detection module 202 can be configured to detect a frequency drop in the power grid as a potential disturbance. For example, the early electrical detection module 202 can be configured to monitor one or more characteristics or electrical properties of the power grid, such as frequency, voltage, current, power, or power factor associated with the power grid. Based on changes in the power grid characteristics or electrical properties, the early electrical detection module 202 can determine whether a transient event is occurring on the power grid. For example, if one or more of the frequency, voltage, current, power, or power factor associated with the power grid increases or decreases beyond a threshold, the early electrical detection module 202 can determine that a transient event is occurring or is otherwise about to occur. In one example, the AVR / exciter controller 200 can sense the rate of change of the electrical frequency at the generator terminals and determine the rate of change of the shaft acceleration (where the rate of change is one of the electrical characteristics monitored by the AVR / exciter controller 200) to determine whether a transient event is occurring. When a transient event is detected, the AVR / exciter controller 200 can send a transient event notification 220 to the turbine controller 210. Because the AVR / exciter controller 200 can be coupled to both the generator and the exciter, it can detect grid events faster and more reliably than speed measurement techniques.

[0024] The AVR / exciter controller 200 can communicate with the turbine controller 210. The turbine controller 210 can be configured to control the operation of a turbine, such as an aero-derivative gas turbine. The turbine controller 210 can receive notifications 220 of transient events from the AVR / exciter controller 200. The turbine controller 210 can adjust the turbine operation based on the notifications 220. For example, the turbine controller 210 can adjust the turbine operation based on modeled electrical values ​​and / or on the dynamics of fuel demand from the turbine's fuel valve regulator.

[0025] Upon receiving notification 220 from the AVR / exciter controller 200, the turbine controller 210 can modify the turbine's first operating parameter 240 by replacing the conventional dynamic 232 of the turbine's fuel demand with an improved dynamic 230 of the turbine's fuel demand. This dynamic replacement can adjust the first operating parameter 240 to increase or decrease fuel in response to a detected event. The first operating parameter 240 can be modified due to notification 220. The dynamic replacement can be temporary in response to an event and can return to normal operation after the event has passed. This flexible dynamic of the fuel valve control loop also ensures rapid response without compromising stability.

[0026] In some implementations, in addition to or instead of modifying fuel dynamics, turbine controller 210 may adjust a second operating parameter 284 in response to notification 220. The second operating parameter 284 will be a measurement of generator power. Due to the rotational inertia of the rotating machine coupled to the generator, the rotating machine gains kinetic energy as its rotational speed increases. When a grid transient occurs that causes a change in rotational speed, the kinetic energy also changes. The rate of change of kinetic energy causes a component of the electrical output (and / or input) known as the inertial response, which is superimposed on the component of the electrical output generated by the working fluid of the turbine in the generator (e.g., an observed increase in power, but not due to an increase in fuel in the combustor). For example, a negative grid frequency transient event on a high-inertia machine operating at constant power demand will result in a large positive inertial response that will increase power feedback, thus introducing a large negative error into the fuel regulator, causing the fuel regulator to incorrectly reduce fuel when the expected response to the frequency drop is to increase fuel to increase power and restore the system frequency. To this end, by using a switching feedback mechanism 284 to detect event 220, the turbine controller, which adjusts the fuel flow to regulator 270 based on the error 260 between power demand 250 and power feedback 290, can have an improved response to electrical transient events. If it is known and detected that event 220 will cause an undesirable fuel regulator response, the switching feedback mechanism can select between measured electrical power 282 or modeled power output 280 that may not include inertial response. Thus, turbine controller 210 can replace the MW value 282 measured by the wattmeter with the MW modeled value 280. The replacement of the value can adjust a second operating parameter 284 to increase or decrease fuel in response to the detected event. The replacement of the value can be temporary in response to the event and can return to normal operation after the event has passed.

[0027] In some implementations, turbine controller 210 may generate or determine MW modeling value 280. For example, turbine controller 210 may determine MW modeling value 280 based on the exhaust pressure of the gas turbine high-pressure compressor. By using MW modeling value 280, turbine controller 210 may avoid reading the inertial response at the wattmeter during grid events. In some cases, MW modeling value 280 may be calculated internally by turbine controller 210 based on variable geometry and fuel demand.

[0028] The first operating parameter 240 can be fed to the MW demand module 250 at the turbine controller 210, which can be used to control the operation of the valve 260. Similarly, the second operating parameter 284 can be fed to the MW feedback module 290 at the turbine controller 210, which can also be used to control the operation of the valve 260. The valve 260 can be used to supply fuel to the fuel regulator 270 to operate the turbine.

[0029] Therefore, turbine controller 210 can be configured to generate a modeled value for electricity, wherein the modeled value is a megawatt modeled value generated based on the compressor discharge pressure of the compressor at the turbine. The modeled value can temporarily replace the actual generator power reading at the turbine's wattmeter. Furthermore, turbine controller 210 can be configured to regulate the dynamics of fuel demand on the turbine's fuel valve regulator, wherein the fuel demand dynamics are flexible, and wherein the fuel demand dynamics can be regulated by temporarily replacing the first dynamic with a second dynamic. The second dynamic can result in controlled acceleration of the turbine. In some embodiments, turbine controller 210 can also be configured to determine the grid frequency boundary and increase the valve response time to avoid oscillations in the turbine frequency response. Some embodiments can be configured such that the turbine's fuel actuator reaches 95% of its movement between the initial and final positions at a minimum point frequency of approximately 4 seconds (49 Hz) of the nominal 50 Hz frequency.

[0030] Therefore, the control system ensures the reliability of the turbine response to frequency events under harsh grid conditions and does not use conventional speed control. The turbine controller 210 can activate controlled acceleration of the turbine via a flexible dynamic response to notification 220 through fuel valve control without affecting stability. Embodiments of this disclosure can regulate one or more turbine operations based on modeled electrical values, where one or more operations include a main frequency algorithm and dynamics of fuel demand on the valve regulator. Therefore, instantaneous power can be provided upon detection of a drop in the main grid frequency.

[0031] Figure 3 This is an exemplary processing flow 300 for providing rapid load support for grid frequency transient events, as may be described herein. Figure 3 One or more of the operations described herein may be performed in different orders and / or by different computer systems in the same computer system or in a distributed computing environment. In one example, Figure 3 The operation can be performed by Figure 2 The AVR / exciter controller 200 is executed.

[0032] At box 310, a first controller (such as an AVR / exciter controller 200) can monitor a first set of electrical characteristics associated with the power grid. For example, the first controller can monitor frequency, voltage, current, power, power factor, and / or other electrical characteristics associated with the power grid.

[0033] At determination block 320, the first controller can determine whether a sudden change in the power grid frequency exists. For example, the first controller 210 can determine whether one or more characteristics of the power grid, such as the power grid frequency, suddenly increases or decreases by more than a threshold amount. If it is determined at determination block 320 that there is no sudden change in the power grid frequency, the process flow 300 can return to block 310, and the first controller can continue monitoring. If it is determined at determination block 320 that a sudden change in the power grid frequency exists, the process flow 300 can proceed to block 330.

[0034] At box 330, the first controller can determine the presence of a transient event on the power grid based on a first set of electrical characteristics. For example, the first controller can determine the presence of a transient event on the power grid based on the fact that the power grid frequency changes by more than a threshold amount over a certain time period.

[0035] At box 340, the first controller can send a notification of a transient event to the second controller. For example, the first controller can send a notification of a transient event to the turbine controller.

[0036] At box 350, the first controller can activate controlled acceleration of the turbine. In some embodiments, the first controller can activate controlled acceleration of the turbine by causing a second controller to activate controlled acceleration. Controlled acceleration can reduce the risk of power loss due to rapid changes in grid frequency.

[0037] Figure 4 This is an exemplary processing flow 400 for providing rapid load support for grid frequency transient events, as may be described herein. Figure 4 One or more of the operations described herein may be performed in different orders and / or by different computer systems in the same computer system or in a distributed computing environment. In one example, Figure 4 The operation can be performed by Figure 2 The turbine controller 210 performs the operation.

[0038] At box 410, the turbine controller of the turbine can receive notification of transient events. For example, the AVR / exciter controller can detect transient events at the generator and / or the power grid, and the turbine controller can receive notification of transient events from the AVR / exciter controller.

[0039] At box 420, the turbine controller may determine a MW modeling value based on the compressor discharge pressure of the compressor at the turbine to replace the measured wattmeter value. For example, the turbine controller may cause the measured wattmeter value to be replaced with the MW modeling value, at least temporarily. The MW modeling value may be determined based on the compressor discharge pressure of the compressor at the turbine and may reflect transient events.

[0040] At box 430, the turbine controller determines an improved dynamic fuel value for fuel demand. The improved dynamic fuel value can be used, at least temporarily, as an alternative to the conventional dynamic value.

[0041] At box 440, the turbine controller can use improved dynamic values ​​to regulate fuel demand. For example, the turbine controller can adjust the dynamics of fuel demand to the turbine's fuel valve regulator.

[0042] At optional box 450, the turbine controller can adjust the main frequency algorithm used to run the turbine.

[0043] Therefore, the turbine controller allows the gas turbine to operate on a variety of fuels and provides a rapid response in the event of a grid event, and provides improved control of the fuel supply valves when controlled acceleration of the turbine is required.

[0044] It should be apparent that the foregoing only relates to certain embodiments of this application and the resulting patent. Many changes and modifications can be made herein by those skilled in the art without departing from the general spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A system for providing rapid load support using a gas turbine, the system comprising: A turbine, the turbine including a first controller; A generator connected to the turbine, wherein the generator is configured to supply power to the grid; and An exciter configured to provide a direct current (DC) voltage and a DC current to the rotor of the generator, wherein the exciter includes a second controller configured to: Monitor the first set of electrical characteristics associated with the power grid; Based on the first set of electrical characteristics, it is determined that a transient event exists on the power grid; as well as Send the notification of the transient event to the first controller; The first controller is configured to adjust the operation of the turbine based on the notification; as well as The first controller is configured as follows: The modeling value for generating electricity is determined based on the compressor discharge pressure of the compressor at the turbine, and the modeling value is configured to temporarily replace the actual kinetic energy reading at the wattmeter of the turbine. In response to the notification, the conventional dynamics of the turbine's fuel demand are temporarily replaced by improved dynamics of the turbine's fuel valve regulator; and After the transient event has passed, the conventional dynamics of fuel demand return to the fuel valve regulator of the turbine.

2. The system of claim 1, wherein the first controller is configured to regulate the operation of the turbine based on electrical modeling values.

3. The system of claim 1, wherein the modeling value is a megawatt modeling value generated based on the compressor discharge pressure of the compressor at the turbine.

4. The system of claim 1, wherein the first controller is configured to regulate the dynamics of the fuel demand of the fuel valve regulator of the turbine.

5. The system of claim 4, wherein the dynamics of fuel demand are flexible.

6. The system of claim 4, wherein the dynamic of fuel demand is adjusted by temporarily replacing the first dynamic with a second dynamic.

7. The system of claim 6, wherein the second dynamic causes controlled acceleration of the turbine.

8. The system of claim 1, wherein the second controller determines that the transient event exists on the power grid when the frequency, voltage, current, power, or power factor associated with the power grid increases or decreases beyond a threshold.

9. The system of claim 1, wherein the second controller is further configured to: The rate of change of electrical frequency at the terminals of the sensed generator; and Determine the rate of change of the axial acceleration; The rate of change is one of the electrical characteristics in the first set of electrical characteristics.

10. The system of claim 1, wherein the first controller is configured to adjust the main frequency algorithm.

11. The system of claim 1, wherein the first controller is configured to determine the grid frequency boundary and increase the valve response time to avoid oscillation.

12. The system of claim 1, wherein the turbine is an aero-derivative gas turbine.

13. A method for providing improved load support for power grid frequency transient events, the method comprising: The first controller monitors the first set of electrical characteristics associated with the power grid; The first controller determines the presence of a transient event on the power grid based on the first set of electrical characteristics; as well as Send the notification of the transient event to the second controller; The second controller is configured to adjust the turbine's operation based on the notification in the following ways: (i) adjusting the dynamics of the fuel demand of the turbine's fuel valve regulator, and (ii) adjusting the main frequency algorithm; and The first controller is configured as follows: The modeling value for generating electricity is determined based on the compressor discharge pressure of the compressor at the turbine, and the modeling value is configured to temporarily replace the actual kinetic energy reading at the wattmeter of the turbine. In response to the notification, the conventional dynamics of the turbine's fuel demand are temporarily replaced by improved dynamics of the turbine's fuel valve regulator; and After the transient event has passed, the conventional dynamics of fuel demand return to the fuel valve regulator of the turbine.

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