A steam turbine protection method based on double reverse power protection

Abstract

A steam turbine protection method based on double sets of reverse power protection is applied to the calling process of a reverse power protection device group. The reverse power protection device group is used to drive the generator to operate in reverse power so that the generator can be safely and stably de-energized under abnormal conditions to protect the steam turbine, and the reverse power protection device group is interlocked with each other. The reverse power protection device group includes a first reverse power protection device group and a second reverse power protection device group. The first reverse power protection device group is driven by a first controller, and the second reverse power protection device group is driven by a second controller. The steam turbine protection method includes: after the first controller obtains a steam turbine shutdown signal, the DO card of the first controller is driven to simultaneously notify the first reverse power protection device group and the second reverse power protection device to operate. The first controller also forwards the steam turbine shutdown signal to the second controller, and causes the DO card of the second controller to notify the second reverse power protection device to operate.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine unit safety management, and in particular to a steam turbine protection method based on double sets of reverse power protection. Background Art

[0002] The digital electro-hydraulic control system (hereinafter referred to as DEH: D-Digital Electro-Hydraulic Control System) of the steam turbine of the ultra-supercritical million-unit thermal power generation unit adopts the Siemens T3000 system. The steam turbine emergency shutdown system adopts Siemens safety card components to set up logic judgment for emergency shutdown. The generator reverse power protection adopts the PCS-985G generator protection device, one of which is reverse power protection. The reverse power protection signal is interlocked with the steam turbine emergency shutdown signal. Under abnormal conditions or when the steam turbine generator set needs to be shut down normally, the steam turbine emergency shutdown signal is sent to the reverse power protection, triggering the generator to shut down.

[0003] At present, the emergency shutdown signal of the steam turbine is sent to the first set of reverse power protection device group and the second set of reverse power protection device group through two pairs of controllers. The reverse power protection device group is used to drive the generator to reverse power operation to protect the safe shutdown of the equipment on the steam turbine side. The two pairs of controllers are the first controller and the second controller. After receiving the emergency shutdown signal of the steam turbine, the first controller forwards the emergency shutdown signal of the steam turbine to the second controller through the switch (since the original design of the DO card of the controller has only one, the emergency shutdown signal needs to be forwarded to the second controller). In this process, since the communication transmission takes a certain amount of time, in the case that the first controller fails to drive the first set of reverse power protection device group, the start of the safe shutdown work performed by the second set of reverse power protection device group will have a certain time delay, which may cause the start-up delay of the reverse power protection measures, and ultimately cause damage to the generator. Summary of the invention

[0004] The object of the present invention is to provide a method capable of driving reverse power protection of a generator when a steam turbine is shut down.

[0005] Therefore, the present invention discloses a steam turbine protection method based on double sets of reverse power protection, which is applied to the calling process of the reverse power protection device group, wherein the reverse power protection device group is used to drive the generator to operate in reverse power to provide reverse power protection for the steam turbine;

[0006] The reverse power protection device group includes a first reverse power protection device group and a second reverse power protection device group, the first reverse power protection device group is driven by a first controller, and the second reverse power protection device group is driven by a second controller;

[0007] The steam turbine protection method comprises:

[0008] After the first controller obtains the turbine shutdown signal, it drives the DO card of the first controller to simultaneously notify the first reverse power protection device group and the second reverse power protection device to operate. The first controller also forwards the turbine shutdown signal to the second controller, and enables the DO card of the second controller to notify the second reverse power protection device to operate.

[0009] In some embodiments of the present application, a communication method between controllers is disclosed, and the first controller forwards the turbine shutdown signal to the second controller through a switch.

[0010] In some embodiments of the present application, in order to determine the power value of the generator when performing reverse power operation, the steam turbine protection method further includes:

[0011] The reverse power protection device group determines the power value for driving the generator to operate at reverse power and the time for driving the generator to stop operating at reverse power according to the power generated when the steam turbine is shut down.

[0012] In some embodiments of the present application, a specific method for determining a power value of a generator for reverse power operation is provided, and the method for determining a power value for driving a generator for reverse power operation includes:

[0013] Set the generator power generation corresponding group A[A1, A2, A3, ..., An], where A1 is the first preset power generation, A2 is the second preset power generation, A3 is the third preset power generation, An is the nth preset power generation, and A1<A2<A3<...<An;

[0014] A power corresponding group B [B1, B2, B3, ..., Bn] for reverse power operation of the generator is set, wherein B1 is a first preset operation power, B2 is a second preset operation power, B3 is a third preset operation power, Bn is an nth preset operation power, and B1<B2<B3<...<Bn;

[0015] Get the generator power a;

[0016] If a≤A1, the first preset operating power B1 is determined to be the power B0 of the generator in reverse power operation;

[0017] If A1<a≤A2, then the second preset operating power B2 is determined to be the power B0 of the generator in reverse power operation;

[0018] If A2<a≤A3, the third preset operating power B3 is determined to be the power B0 of the generator in reverse power operation;

[0019] …;

[0020] If An-1<a≤An, the nth preset operating power Bn is determined to be the power B0 of the generator in reverse power operation.

[0021] In some embodiments of the present application, a method for determining the reverse power operation time of a driving generator is disclosed. The method for determining the reverse power operation time of a driving generator includes:

[0022] According to the determined power of the generator in reverse power operation, the reverse power operation time of the generator is analyzed and determined.

[0023] In some embodiments of the present application, in order to determine the time of reverse power operation of the generator, a specific method for determining the time of reverse power operation of the generator is disclosed. The method for determining the time of reverse power operation of the generator according to the reverse power operation power of the generator is specifically as follows:

[0024] Set the operation time corresponding group C [C1, C2, C3, ..., Cn], wherein C1 is the first preset operation time, C2 is the second preset operation time, C3 is the third preset operation time, Cn is the nth preset operation time, and C1<C2<C3<...<Cn;

[0025] If it is determined that the first preset operating power B1 is the power of the generator in reverse power operation, then the first preset operating time C1 is determined as the time for driving the generator to operate in reverse power;

[0026] If it is determined that the second preset operating power B2 is the power of the generator in reverse power operation, then the second preset operating time C2 is determined as the time for driving the generator to operate in reverse power;

[0027] If it is determined that the third preset operating power B3 is the power of the generator in reverse power operation, then the third preset operating time C3 is determined as the time for driving the generator to operate in reverse power;

[0028] …;

[0029] If it is determined that the nth preset operating power Bn is the power of the generator for reverse power operation, then the nth preset operating time Cn is determined as the time for driving the generator for reverse power operation.

[0030] In some embodiments of the present application, in order to more accurately determine the power value of the generator when it is in reverse power operation, the method for determining the power value of driving the generator to operate in reverse power also includes:

[0031] The air flow rate in the steam turbine is obtained, and the power parameters of the generator in reverse power operation are corrected according to the air flow rate in the steam turbine.

[0032] In some embodiments of the present application, a method for determining the air flow rate in a steam turbine is disclosed. The method for obtaining the air flow rate in a steam turbine includes:

[0033] The gas temperature after the turbine is shut down is obtained in real time, and the gas flow after the turbine is shut down is determined based on a preset standard operating condition conversion model.

[0034] In some embodiments of the present application, a specific method for correcting parameters of the power of a generator in reverse power operation is disclosed. The method for correcting parameters of the power of a generator in reverse power operation includes:

[0035] Set the air flow difference corresponding group H [H1, H2, H3, ..., Hn], where H1 is the first preset air flow difference, H2 is the second preset air flow difference, H3 is the third preset air flow difference, Hn is the nth preset air flow difference, and H1<H2<H3<...<Hn;

[0036] Set a correction coefficient corresponding group K [K1, K2, K3, ..., Kn], where K1 is the first correction coefficient, K2 is the second correction coefficient, K3 is the third correction coefficient, and Kn is the nth correction coefficient;

[0037] Obtain the air flow h in the steam turbine in real time, and determine the theoretical air flow z of the steam turbine under standard operating conditions at this moment, and calculate the difference between the two h0=hz;

[0038] Obtaining a preliminarily determined power value B0 of the generator in reverse power operation;

[0039] If h0≤H1, the power value of the generator in reverse power operation is finally determined to be B00=K1*B0;

[0040] If H1<h0≤H2, the power value of the generator in reverse power operation is finally determined to be B00=K2*B0;

[0041] If H2<h0≤H3, the power value of the generator in reverse power operation is finally determined to be B00=K3*B0;

[0042] …;

[0043] If Hn-1<h0≤Hn, the power value of the generator's reverse power operation is finally determined to be B00=Kn*B0.

[0044] The present application discloses a steam turbine protection method based on double sets of reverse power protection. Compared with the prior art, the present application has the following advantages:

[0045] In the conventional reverse power protection method of a steam turbine, the first controller is only required to forward the steam turbine shutdown signal to the second controller, and the DO card of the first controller is not required to simultaneously notify the first set of reverse power protection devices and the second set of reverse power protection devices. In comparison, in order to notify the second set of reverse power protection devices to operate, the time consumed in transmitting the steam turbine shutdown signal to the second controller is greater than that directly notifying the second set of reverse power protection devices from the first controller to operate. Therefore, the technical solution of the present application makes the execution speed of the reverse power protection action faster, effectively reducing the damage during turbine shutdown.

[0046] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A diagram showing the steps of a method for transmitting information between controllers in an embodiment of the present application;

[0048] Figure 2 This is a conventional flow chart of reverse power protection of a steam turbine in an embodiment of the present application;

[0049] Figure 3 This is an improved flow chart of reverse power protection of the steam turbine in the embodiment of the present application. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0051] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0052] Example:

[0053] The object of the present invention is to provide a method capable of driving reverse power protection of a generator when a steam turbine is shut down.

[0054] Therefore, the present invention discloses a steam turbine protection method based on double sets of reverse power protection, which is applied to the calling process of the reverse power protection device group, and the reverse power protection device group is used to drive the generator to operate in reverse power to protect the steam turbine from reverse power.

[0055] The reverse power protection device group includes a first reverse power protection device group and a second reverse power protection device group. The first reverse power protection device group is driven by a first controller, and the second reverse power protection device group is driven by a second controller.

[0056] Among them, the first reverse power protection device group and the second reverse power protection device group are both related devices for driving the generator to operate in reverse power.

[0057] The steam turbine protection method comprises:

[0058] After the first controller obtains the turbine shutdown signal, it drives the DO card of the first controller to simultaneously notify the first reverse power protection device group and the second reverse power protection device to operate. The first controller also forwards the turbine shutdown signal to the second controller, and enables the DO card of the second controller to notify the second reverse power protection device to operate.

[0059] In order to facilitate the understanding of the above technical solution, please refer to Figure 1 , the method and steps of information transmission between controllers are now disclosed:

[0060] S100: The first controller obtains a steam turbine emergency shutdown signal, analyzes the steam turbine emergency shutdown signal, and generates a first set of reverse power protection instructions and a second set of reverse power protection instructions.

[0061] S200, the first controller sends a first set of reverse power protection instructions to a first set of reverse power protection device groups, and sends a second set of reverse power protection instructions to a second set of reverse power protection device groups;

[0062] S300, the first controller forwards the turbine emergency shutdown signal to the second controller, and generates a second set of reverse power protection instructions via the second controller.

[0063] S400: The second controller sends a second set of reverse power protection instructions to a second set of reverse power protection device groups.

[0064] See also Figure 2 In the conventional steam turbine reverse power protection method, the first controller is only required to forward the steam turbine shutdown signal to the second controller, and the DO card of the first controller is not required to simultaneously notify the first set of reverse power protection device groups and the second set of reverse power protection device groups. Figure 3In order to notify the second set of reverse power protection device group to operate, the time consumed to transmit the turbine shutdown signal to the second controller is longer than directly notifying the second set of reverse power protection device group to operate by the first controller. Therefore, the technical solution of the present application makes the execution speed of the reverse power protection action faster, effectively reducing the damage during turbine shutdown.

[0065] In order to manually determine whether to start the reverse power protection action on the steam turbine, a relay dry node is also connected in parallel between the controller and the reverse power protection device group.

[0066] It should be noted that the information transmission between controllers needs to go through the intermediate communication device, and this process takes a certain amount of time. However, directly using the different channels of the DO card of the first controller to notify the second set of reverse power protection devices can be more efficient, reducing the delay time of the reverse power operation of the generator, thereby reducing the shutdown wear inside the turbine.

[0067] In some embodiments of the present application, a communication method between controllers is disclosed, and the first controller forwards the turbine shutdown signal to the second controller through a switch.

[0068] In some embodiments of the present application, in order to determine the power value of the generator when it is in reverse power operation, thereby reducing the energy consumption caused by excessive power increase of the generator in reverse power operation, and the problem that the fan blades inside the steam turbine stop too quickly, causing the air flow velocity to accelerate and wear the inside of the steam turbine, the steam turbine protection method is improved, and the steam turbine protection method also includes:

[0069] The reverse power protection device group determines the power value for driving the generator to operate at reverse power and the time for driving the generator to stop operating at reverse power according to the power generated when the steam turbine is shut down.

[0070] It should be understood that the power generation when the turbine is shut down reflects the amount of work done by the turbine at this time. If the power value of the generator running in reverse power is too low, it will cause the blades inside the turbine to rotate rapidly, and then cause wear inside the turbine. In order to avoid this situation, it is necessary to make the power value of the generator in the reverse power operation state more accurate.

[0071] In some embodiments of the present application, a specific method for determining a power value of a generator for reverse power operation is provided, and the method for determining a power value for driving a generator for reverse power operation includes:

[0072] The first step is to set the generator power generation corresponding group A[A1, A2, A3, ..., An], where A1 is the first preset power generation, A2 is the second preset power generation, A3 is the third preset power generation, An is the nth preset power generation, and A1<A2<A3<...<An.

[0073] The second step is to set the power corresponding group B [B1, B2, B3, ..., Bn] for the reverse power operation of the generator, where B1 is the first preset operating power, B2 is the second preset operating power, B3 is the third preset operating power, Bn is the nth preset operating power, and B1<B2<B3<...<Bn.

[0074] The third step is to obtain the generator power a (the generator power when the generator is shut down).

[0075] If a≤A1, the first preset operating power B1 is determined to be the power B0 of the generator operating in reverse power.

[0076] If A1<a≤A2, the second preset operating power B2 is determined to be the power B0 of the generator operating in reverse power.

[0077] If A2<a≤A3, the third preset operating power B3 is determined to be the power B0 of the generator operating in reverse power.

[0078] ….

[0079] If An-1<a≤An, the nth preset operating power Bn is determined to be the power B0 of the generator in reverse power operation.

[0080] In some embodiments of the present application, a method for determining the reverse power operation time of a driving generator is disclosed. The method for determining the reverse power operation time of a driving generator includes: analyzing and determining the reverse power operation time of the generator based on the determined reverse power operation power of the generator.

[0081] What needs to be understood here is that during the reverse power operation of the generator, it is actually through the work done on the steam turbine that the steam turbine is shut down safely. If the generator has a large power when operating in reverse power, then the external output power when the steam turbine is shut down will be large, and naturally the reverse power operation time of the generator will be longer. Conversely, if the generator has a small power when operating in reverse power, then the external output power when the steam turbine is shut down will be small, and naturally the reverse power operation time of the generator will be shorter.

[0082] In some embodiments of the present application, in order to determine the time of reverse power operation of the generator, a specific method for determining the time of reverse power operation of the generator is disclosed. The method for determining the time of reverse power operation of the generator according to the reverse power operation power of the generator is specifically as follows:

[0083] The first step is to set the operating time corresponding group C [C1, C2, C3, ..., Cn], where C1 is the first preset operating time, C2 is the second preset operating time, C3 is the third preset operating time, Cn is the nth preset operating time, and C1<C2<C3<...<Cn.

[0084] The second step is to specifically analyze the time it takes to drive the generator to run in reverse power.

[0085] If it is determined that the first preset operating power B1 is the power of the generator for reverse power operation, then the first preset operating time C1 is determined as the time for driving the generator for reverse power operation.

[0086] If it is determined that the second preset operating power B2 is the power of the generator for reverse power operation, then the second preset operating time C2 is determined as the time for driving the generator for reverse power operation.

[0087] If it is determined that the third preset operating power B3 is the power of the generator for reverse power operation, then the third preset operating time C3 is determined as the time for driving the generator for reverse power operation.

[0088] ….

[0089] If it is determined that the nth preset operating power Bn is the power of the generator for reverse power operation, then the nth preset operating time Cn is determined as the time for driving the generator for reverse power operation.

[0090] In some embodiments of the present application, in order to more accurately determine the power value of the generator when operating in reverse power, the method for determining the power value of driving the generator to operate in reverse power also includes: obtaining the air flow rate in the turbine, and performing parameter correction on the power of the generator operating in reverse power according to the air flow rate in the turbine.

[0091] In some embodiments of the present application, a method for determining the air flow rate in a steam turbine is disclosed. The method for obtaining the air flow rate in a steam turbine includes: obtaining the gas temperature after the steam turbine is shut down in real time, and determining the air flow rate after the steam turbine is shut down based on a preset standard operating condition conversion model.

[0092] The preset standard working condition conversion model is as follows:

[0093]

[0094]

[0095] In the formula: subscript O represents the known standard operating condition (rated operating condition) parameters, subscript 1 represents the parameters before the stage group, and subscript represents the parameters after the stage group; G is the main steam flow rate of the new operating condition, t / h; P is the pressure after the regulating stage of the new operating condition, MPa; T represents the temperature after the regulating stage of the new operating condition, K.

[0096] Formula (1) is used to calculate the flow rate after the regulating stage of a condensing steam turbine, and formula (2) is used to calculate the flow rate of a single pressure stage group.

[0097] The application conditions of formula (1) are: before and after the operating conditions change, the flow area after the regulating stage remains unchanged, and the extraction flow rate is linearly related to the main steam flow rate. The application conditions of formula (2) are: there are enough stages in the stage group, the steam flow rate is subsonic, and the flow area remains unchanged. The flow rate in the two formulas originally refers to the flow rate of the flow part. Considering that the steam leakage flow rate of the steam seal and valve stem is relatively small and is approximately proportional to the main steam flow, it is generally replaced by the main steam flow rate for processing.

[0098] The above-mentioned preset standard operating condition model can also be other methods. For example, based on the characteristics of BP neural network or vector machine regression method, it can self-learn according to the real-time data of the unit on site to improve the calculation accuracy of the main steam flow. The calculation model is universal and can achieve a calculation accuracy of 1% error after training with limited sample data. It can diagnose whether the flow area changes through relevant parameters and calculate a relatively correct main steam flow.

[0099] In some embodiments of the present application, a method for performing parameter correction on the power of a generator in reverse power operation is disclosed. The method for performing parameter correction on the power of a generator in reverse power operation includes:

[0100] The first step is to set the air flow difference corresponding group H [H1, H2, H3, ..., Hn], where H1 is the first preset air flow difference, H2 is the second preset air flow difference, H3 is the third preset air flow difference, Hn is the nth preset air flow difference, and H1<H2<H3<...<Hn.

[0101] The second step is to set the correction coefficient corresponding group K [K1, K2, K3, ..., Kn], where K1 is the first correction coefficient, K2 is the second correction coefficient, K3 is the third correction coefficient, and Kn is the nth correction coefficient.

[0102] The air flow difference corresponding group H and the correction coefficient corresponding group K in the first step can be obtained through multiple experiments and engineer experience.

[0103] The third step is to obtain the air flow h in the steam turbine in real time, determine the theoretical air flow z of the steam turbine under the standard operating conditions at this moment, and calculate the difference between the two h0=hz.

[0104] The fourth step is to obtain the power value B0 of the generator reverse power operation which has been preliminarily determined.

[0105] If h0≤H1, the power value of the generator's reverse power operation is finally determined to be B00=K1*B0.

[0106] If H1<h0≤H2, the power value of the generator's reverse power operation is finally determined to be B00=K2*B0.

[0107] If H2<h0≤H3, the power value of the generator's reverse power operation is finally determined to be B00=K3*B0.

[0108] ….

[0109] If Hn-1<h0≤Hn, the power value of the generator's reverse power operation is finally determined to be B00=Kn*B0.

[0110] The present application is based on solving the problem of turbine damage caused by turbine shutdown due to some reason, improves the existing method of reverse power protection of turbine by generator, improves the instruction information transmission method between controllers and between reverse power protection device groups, solves the problem of generator reverse power action start-up delay caused by information transmission delay between controllers in the prior art, and thus reduces the degree of self-damage of the turbine during shutdown. The technical solution of the present application also makes the power output of the generator more accurate during reverse power operation, which not only further effectively reduces the damage to the turbine, but also reduces energy consumption.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A steam turbine protection method based on double reverse power protection, applied to the calling process of a reverse power protection device group, wherein the reverse power protection device group is used to drive the generator to operate in reverse power to provide reverse power protection for the steam turbine, characterized in that: The reverse power protection device group includes a first reverse power protection device group and a second reverse power protection device group, the first reverse power protection device group is driven by a first controller, and the second reverse power protection device group is driven by a second controller; The steam turbine protection method comprises: After the first controller obtains the steam turbine shutdown signal, the DO card of the first controller is driven to simultaneously notify the first reverse power protection device group and the second reverse power protection device group to operate, and the first controller also forwards the steam turbine shutdown signal to the second controller, and causes the DO card of the second controller to notify the second reverse power protection device group to operate; The steam turbine protection method further comprises: The reverse power protection device group determines the power value of the generator reverse power operation and the reverse power operation time of the generator according to the power generation power when the steam turbine is shut down; The method for determining the power value of the generator reverse power operation comprises: Set the generator power generation corresponding group A[A1, A2, A3, ..., An], where A1 is the first preset power generation, A2 is the second preset power generation, A3 is the third preset power generation, An is the nth preset power generation, and A1<A2<A3<...<An; A power corresponding group B [B1, B2, B3, ..., Bn] for reverse power operation of the generator is set, wherein B1 is a first preset operation power, B2 is a second preset operation power, B3 is a third preset operation power, Bn is an nth preset operation power, and B1<B2<B3<...<Bn; Get the generator power a; If a≤A1, the first preset operating power B1 is determined to be the power B0 of the generator in reverse power operation; If A1<a≤A2, then the second preset operating power B2 is determined to be the power B0 of the generator in reverse power operation; If A2<a≤A3, the third preset operating power B3 is determined to be the power B0 of the generator in reverse power operation; …； If An-1<a≤An, the nth preset operating power Bn is determined to be the power B0 of the generator in reverse power operation; The method for determining the time of reverse power operation of the generator comprises: Analyzing and determining the reverse power operation time of the generator according to the determined reverse power operation power of the generator; The method for analyzing and determining the reverse power operation time of the generator according to the determined reverse power operation power of the generator is specifically: Set the operation time corresponding group C [C1, C2, C3, ..., Cn], wherein C1 is the first preset operation time, C2 is the second preset operation time, C3 is the third preset operation time, Cn is the nth preset operation time, and C1<C2<C3<...<Cn; If it is determined that the first preset operating power B1 is the power of the generator in reverse power operation, then the first preset operating time C1 is determined to be the time for the generator to operate in reverse power; If it is determined that the second preset operating power B2 is the power of the generator in reverse power operation, then the second preset operating time C2 is determined to be the time for the generator to operate in reverse power; If it is determined that the third preset operating power B3 is the power of the generator in reverse power operation, then the third preset operating time C3 is determined to be the time for the generator to operate in reverse power; …； If it is determined that the nth preset operating power Bn is the power of the generator in reverse power operation, then the nth preset operating time Cn is determined to be the time for the generator to operate in reverse power.

2. A steam turbine protection method based on double sets of reverse power protection according to claim 1, characterized in that: The first controller forwards the turbine shutdown signal to the second controller through the switch.

3. A steam turbine protection method based on double sets of reverse power protection according to claim 2, characterized in that: The method for determining the power value of the generator reverse power operation also includes: The air flow rate in the steam turbine is obtained, and the power parameters of the generator in reverse power operation are corrected according to the air flow rate in the steam turbine.

4. A steam turbine protection method based on double sets of reverse power protection according to claim 3, characterized in that: Methods for obtaining the air flow in the steam turbine include: The gas temperature after the turbine is shut down is obtained in real time, and the gas flow after the turbine is shut down is determined based on a preset standard operating condition conversion model.

5. A steam turbine protection method based on double sets of reverse power protection according to claim 4, characterized in that: The method for correcting the parameters of the power of the generator in reverse power operation includes: Set the air flow difference corresponding group H [H1, H2, H3, ..., Hn], where H1 is the first preset air flow difference, H2 is the second preset air flow difference, H3 is the third preset air flow difference, Hn is the nth preset air flow difference, and H1<H2<H3<...<Hn; Set a correction coefficient corresponding group K [K1, K2, K3, ..., Kn], where K1 is the first correction coefficient, K2 is the second correction coefficient, K3 is the third correction coefficient, and Kn is the nth correction coefficient; Obtain the air flow h in the steam turbine in real time, and determine the theoretical air flow z of the steam turbine under standard operating conditions at this moment, and calculate the difference between the two h0=hz; Obtaining a preliminarily determined power value B0 of the generator in reverse power operation; If h0≤H1, the power value of the generator in reverse power operation is finally determined to be B00=K1*B0; If H1<h0≤H2, the power value of the generator in reverse power operation is finally determined to be B00=K2*B0; If H2<h0≤H3, the power value of the generator in reverse power operation is finally determined to be B00=K3*B0; …； If Hn-1<h0≤Hn, the power value of the generator's reverse power operation is finally determined to be B00=Kn*B0.

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