Steam turbine control method and system of photo-thermal unit and power plant

Abstract

The invention discloses a steam turbine control method and system of a photo-thermal unit and a power plant. The method comprises the steps that firstly, a rotating speed set value change rate set value of a steam turbine is obtained through a rotating speed control strategy; and the set value of the rotating speed set value change rate serves as input of an integral time generation function of variable parameter type PID control so as to achieve variable parameter PID control over the rotating speed of the steam turbine. Traditional fixed-parameter single-loop PID control is changed into variable-parameter PID control, the rotating speed adjusting accuracy of the steam turbine can be improved, the probability that the steam turbine overspeeds and the rotating speed fluctuates drastically in the starting process before grid connection is reduced, and the operation stability of the photo-thermal unit is improved.

Description

Technical Field

[0001] The present application relates to the field of solar thermal power generation, and in particular to a method and system for controlling a steam turbine of a solar thermal unit and a power plant. Background Art

[0002] CSP units are the core equipment of CSP plants. Their functions encompass heat conversion, power generation, and energy storage, making them the key to achieving the "solar-to-heat-to-electricity" transformation. By combining different technology approaches (tower and trough types, among others) with thermal storage systems, CSP units can stably and continuously convert solar energy into electricity, compensating for the intermittent nature of photovoltaic and wind power generation. They are a key pillar in building a multi-energy, complementary clean energy system.

[0003] In the prior art, the high-pressure exhaust ventilation valves of some CSP units are used only as a means of regulating overheating in the high-pressure cylinders and are not opened at all other times. This results in the startup process being nominally a combined startup of the high- and high-pressure cylinders, but in reality, the majority of the work is done by the low- and medium-pressure cylinders. The high-pressure cylinders only experience minor steam leakage and water drainage, with the majority of the steam flowing through the high-pressure bypass to the reheat steam cooling section. As a result, the CSP unit's steam turbine suffers from poor speed control. During startup before grid connection, the turbine may experience overspeed and significant speed fluctuations, impacting the unit's operational stability. Summary of the Invention

[0004] The present application aims to propose a steam turbine control method, system and power plant for a solar thermal unit, which can improve the accuracy of steam turbine speed regulation, reduce the probability of steam turbine overspeed and large speed fluctuations during the startup process before grid connection, and improve the stability of solar thermal unit operation.

[0005] In a first aspect, an embodiment of the present application provides a method for controlling a steam turbine of a solar thermal power plant, including a speed control strategy, wherein the speed control strategy includes:

[0006] Get the speed setting value change rate setting value of the steam turbine;

[0007] The set value of the speed set value change rate is used as the input of the integral time generating function of the variable parameter PID control to realize the variable parameter PID control of the turbine speed.

[0008] According to some embodiments of the present application, the speed control strategy further includes:

[0009] Obtain the speed set value, actual speed value and target deviation threshold;

[0010] Calculating a first deviation value according to the speed setting value and the actual speed value, wherein the first deviation value is the difference between the speed setting value and the actual speed value;

[0011] When the first deviation value is greater than the target deviation threshold, a first integral separation control signal is generated, the first integral separation control signal being used to instruct the output of the variable parameter PID to stop superimposing an integral operation increment until the first deviation value is less than or equal to the target deviation threshold.

[0012] According to some embodiments of the present application, the rotating speed control strategy further comprises:

[0013] The rotating speed of the steam turbine is acquired, and it is determined whether the rotating speed of the steam turbine is in a speed-up stage or a constant speed stage.

[0014] In the speed-up stage, PID control of the rotating speed of the steam turbine is performed through first PID control parameters, the first PID control parameters being used to instruct a PID control strategy in which proportional action is dominant.

[0015] In the constant speed stage, PID control of the rotating speed of the steam turbine is performed through second PID control parameters, the second PID control parameters being used to instruct a PID control strategy in which proportional and integral actions are dominant.

[0016] According to some embodiments of the present application, the rotating speed control strategy further comprises:

[0017] The rotating speed of the steam turbine is acquired, and it is determined whether the rotating speed of the steam turbine is in a critical zone range.

[0018] In the case that the rotating speed of the steam turbine is not in the critical zone range, a difference between a rotating speed set value and an actual rotating speed value of the steam turbine is calculated, if the difference is greater than 20 rpm, the change of the rotating speed set value is stopped, and if the difference is less than or equal to 20 rpm, the change of the rotating speed set value is resumed.

[0019] According to some embodiments of the present application, the method further comprises a bypass control strategy, the bypass control strategy comprising:

[0020] An intermediate control valve control instruction is acquired.

[0021] The intermediate control valve control instruction is taken as input, and a target feedforward amount is obtained according to a feedforward function.

[0022] The target feedforward amount is superimposed as a feedforward of low bypass valve PID control to an output instruction.

[0023] According to some embodiments of the present application, the method further comprises a bypass control strategy, the bypass control strategy comprising:

[0024] In a spin-up mode, a high bypass valve is controlled to adjust a cold section pressure of reheated steam.

[0025] After a high discharge check valve is opened, the spin-up mode is reset, and a main steam pressure control mode is switched to.

[0026] According to some embodiments of the present application, after resetting the flushing mode after the high pressure exhaust check valve is opened and switching to the main steam pressure control mode, the method further includes:

[0027] Monitor the exhaust temperature of high-pressure cylinder;

[0028] When the high-pressure cylinder exhaust temperature is lower than the target temperature threshold, the high bypass control instruction is locked.

[0029] According to some embodiments of the present application, the method further includes a bypass control strategy, wherein the bypass control strategy includes:

[0030] In the start-up mode, obtain the current main steam pressure value of the turbine;

[0031] The output of the high bypass valve PID control is limited according to the current main steam pressure value of the turbine.

[0032] In a second aspect, an embodiment of the present application provides a steam turbine control system for a solar thermal unit, comprising: a control host, wherein the control host implements steam turbine control of the solar thermal unit through the above-mentioned steam turbine control method for the solar thermal unit.

[0033] In a third aspect, an embodiment of the present application provides a power plant, comprising a solar thermal unit and a control host, wherein the control host implements steam turbine control of the solar thermal unit through the above-mentioned steam turbine control method of the solar thermal unit.

[0034] The steam turbine control method, system, and power plant of the solar thermal power plant according to the embodiments of the present application have at least the following beneficial effects:

[0035] In this implementation, the turbine speed setpoint change rate is first obtained; this setpoint is then used as the input to the integral time generation function of the variable-parameter PID control to implement variable-parameter PID control of the turbine speed. This shift from traditional fixed-parameter single-loop PID control to variable-parameter PID control improves the accuracy of turbine speed regulation, reduces the likelihood of turbine overspeed and significant speed fluctuations during startup prior to grid connection, and enhances the operational stability of the CSP unit.

[0036] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0038] Figure 1 This is a flow chart of an embodiment of a steam turbine control method for a solar thermal power plant provided in this application;

[0039] Figure 2 This is a schematic diagram of the structure of the electronic device provided in this application. DETAILED DESCRIPTION

[0040] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0041] In this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the elements.

[0042] In order to solve the problems of the prior art, the embodiments of the present application provide a method, system and power plant for controlling a steam turbine of a solar thermal power plant. The steam turbine control method of a solar thermal power plant provided by the embodiments of the present application is first introduced below.

[0043] Figure 1 A flow chart of a steam turbine control method for a solar thermal power plant provided in an embodiment of the present application is shown. A steam turbine control method for a solar thermal power plant includes a speed control strategy, which includes:

[0044] S101, obtaining a speed setting value change rate setting value of a steam turbine;

[0045] S102: Using the set value of the speed set value change rate as the input of the integral time generating function of the variable parameter PID control to realize the variable parameter PID control of the turbine speed.

[0046] In this implementation, the turbine speed setpoint change rate is first obtained; this setpoint is then used as the input to the integral time generation function of the variable-parameter PID control to implement variable-parameter PID control of the turbine speed. This shift from traditional fixed-parameter single-loop PID control to variable-parameter PID control improves the accuracy of turbine speed regulation, reduces the likelihood of turbine overspeed and significant speed fluctuations during startup prior to grid connection, and enhances the operational stability of the CSP unit.

[0047] The speed setpoint change rate of the turbine in step S101 is the target speed pre-set in the control system, while the speed setpoint change rate refers to the rate of change of the speed target value set in the turbine control system over time. The speed setpoint changes during the run-up and constant speed process. It is derived from the speed target value. The target can be directly changed in steps, but the setpoint must approach the target value at a set rate until it is equal or needs to be maintained. The cold state rise rate is generally 100-200, the warm state is generally 200-300, the hot state is about 300-400, and the extremely hot state is 400-500. Crossing the critical zone requires rapid speed, generally 400-600, and the SAIC unit is generally 600-900.

[0048] In step S102 above, the speed setting value change rate is used as the input of the integral time generating function of the variable parameter PID control to achieve variable parameter PID control of the turbine speed. This means that the speed setting value change rate is used as the input, and the output instruction of the variable parameter PID control is obtained through the corresponding function in the following table to control the turbine speed. The specific function corresponding table is as follows:

[0049] Rate of change of speed setpoint (rpm / min) 0 100 600 700 Integral time (s) 750 750 1200 1200

[0050] It's important to note that the opening and closing of the throttle valve increases and decreases the turbine's flow area. This causes steam expansion and compression, lowering and increasing the main steam and reheat steam pressures. Compared to traditional units, CSP units, due to limitations in heat exchange characteristics and heat source characteristics, have lower heat storage capacity and lower conduction, radiation, and convection heat transfer intensities compared to traditional fossil fuel boilers. This results in lower reheater heat storage and reheat steam specific enthalpy. Consequently, the throttle valve's operation has a greater impact on the reheat steam pressure. Decreased steam parameters can lead to significant speed response lag due to insufficient turbine acceleration energy. Especially when crossing the critical region, a setpoint acceleration rate of 900 rpm is required.

[0051] Since changes in the ramp rate will lead to changes in the throttle valve opening rate, changes in the throttle valve opening rate directly affect the reheat steam pressure. An increase in the ramp rate will inevitably lead to a faster throttle valve opening rate, resulting in faster steam energy release. This, in the absence of sufficient heat storage to replenish the steam, will cause a greater drop in steam pressure, greater inertia in the time lag, and longer parameter recovery time, resulting in slower speed response. Using a single PID controller to adjust parameters will lead to integral saturation. This means that during the period when reheat steam pressure is difficult to recover, the integral computation of the speed deviation is excessive, causing the integral link to oversaturate. Later, after steam pressure recovers, the controller will not be able to recover in time, resulting in overspeed. Therefore, in this application, the speed setpoint change rate is used as an input, and a broken line function outputs different integral time parameters based on different inputs. By switching from a traditional fixed-parameter single-loop PID to a variable-parameter PID for turbine speed control, precise speed control can be achieved. It can meet speed control requirements such as run-up, speed increase, friction check, over-criticality, constant speed at 3000 rpm, and synchronization according to the system's ramp rate, avoiding abnormal conditions such as overspeed and large speed fluctuations.

[0052] In some implementations, the speed control strategy may further include:

[0053] Obtain the speed set value, actual speed value and target deviation threshold;

[0054] Calculating a first deviation value according to the speed setting value and the actual speed value, the first deviation value being the difference between the speed setting value and the actual speed value;

[0055] When the first deviation value is greater than the target deviation threshold, a first integral separation control signal is generated, which is used to instruct the output of the variable parameter PID to stop superimposing the integral operation increment until the first deviation value is less than or equal to the target deviation threshold.

[0056] In this implementation, the speed setpoint, actual speed, and target deviation threshold are first obtained. A first deviation is then calculated based on the speed setpoint and actual speed. Finally, when the first deviation exceeds the target deviation threshold, a first integral separation control signal is generated. This can further improve the accuracy of turbine speed regulation, reduce the probability of turbine overspeed and large speed fluctuations, and enhance the operational stability of the CSP unit.

[0057] It should be noted that when the first deviation value is greater than the target deviation threshold, a first integral separation control signal is generated to control the output of the variable parameter PID to stop superimposing the integral operation increment until the first deviation value is less than or equal to the target deviation threshold. This is equivalent to adding an integral separation link to the PID control. When the pressure of the reheated steam drops due to the opening of the regulating valve, the inertia time of the regulating system has been amplified. If the integration is continued at this time, it will lead to integral saturation. When the pressure rises, it will cause overshoot. For example, in this embodiment, the target deviation threshold is set to 120rpm. That is, when the deviation between the speed setting value and the actual speed value is greater than 120rpm, the output will no longer superimpose the integral operation increment, and the integration will be resumed after the deviation drops back to ≤120rpm.

[0058] In some implementations, the speed control strategy may further include:

[0059] Obtain the turbine speed and determine whether the turbine speed is in the speed-up stage or the speed-constant stage;

[0060] In the speed-up phase, the PID control of the turbine speed is performed by using the first PID control parameter, and the first PID control parameter is used to indicate a PID control strategy based on proportional action;

[0061] In the constant speed stage, the PID control of the turbine speed is performed through the second PID control parameter, and the second PID control parameter is used to indicate a PID control strategy based on the comprehensive effect of proportional and integral.

[0062] In this implementation, the turbine speed is first acquired and determined to be in the acceleration phase or the constant speed phase. During the acceleration phase, PID control of the turbine speed is performed using a first PID control parameter, which indicates a PID control strategy that primarily uses proportional action. During the constant speed phase, PID control of the turbine speed is performed using a second PID control parameter, which indicates a PID control strategy that primarily uses a proportional-integral combination. This can further improve the accuracy of turbine speed regulation, reduce the probability of turbine overspeed and large speed fluctuations, and enhance the operational stability of the CSP unit.

[0063] It should be noted that the steam turbine startup process encompasses the entire process from standstill to stable speed at 3000 rpm, including both a speed-up phase and a constant speed phase. During the speed-up phase, PID control of the turbine speed is performed using a first PID control parameter, which indicates a PID control strategy primarily based on proportional action. During the constant speed phase, PID control of the turbine speed is performed using a second PID control parameter, which indicates a PID control strategy primarily based on proportional-integral combined action. This refers to switching between the PID parameters for the start-up phase and the PID parameters for the constant speed phase at 3000 rpm. The steam turbine startup process is the process from standstill to stable speed at 3000 rpm. In this embodiment, the speed phase from 0 to 2980 rpm is considered the speed-up phase, and the phase from 2980 rpm to 3000 rpm is considered the constant speed phase. In this embodiment, the speed control before 2980 rpm utilizes the PID parameters for the start-up phase, i.e., a PID control strategy primarily based on proportional action. For example, the proportional band is 30, which translates to a proportional gain of 3.33, with the integral calculated using a variable integral function. When the speed is ≥2980rpm, the PID controller parameters are switched, that is, the PID control strategy based on the proportional-integral comprehensive effect is adopted. For example, the proportional band is changed to 50, which is converted into a proportional gain of 2, and the integral time is changed to 120s, which greatly enhances the integral effect. In this embodiment, the speed increase stage parameters are mainly based on the proportional effect, and the integral is small to ensure a fast response without overspeeding. The constant speed stage is mainly based on the proportional-integral comprehensive effect, and the proportional-integral effect is enhanced to quickly respond to speed fluctuations and stabilize to 3000rpm. This allows the speed control to adapt to the speed control characteristics of various working conditions such as rushing, speed increase, synchronous grid connection and load rejection. Therefore, the accuracy of the turbine speed regulation can be further improved, the probability of overspeeding and large speed fluctuations of the turbine can be further reduced, and the stability of the operation of the solar thermal unit can be further improved.

[0064] In some implementations, the speed control strategy may further include:

[0065] Obtain the turbine speed and determine whether the turbine speed is within the critical range;

[0066] When the turbine speed is not within the critical range, the difference between the turbine speed setting value and the actual speed value is calculated. If the difference is greater than 20rpm, the change of the speed setting value is stopped. If the difference is less than or equal to 20rpm, the change of the speed setting value is resumed.

[0067] In this implementation, when the turbine speed is outside the critical range, the difference between the set speed and the actual speed is calculated. If the difference is greater than 20 rpm, the speed setting is stopped. If the difference is less than or equal to 20 rpm, the speed setting is resumed. This can further improve the accuracy of turbine speed regulation, further reduce the probability of turbine overspeed and large speed fluctuations, and further enhance the operational stability of the solar thermal power plant.

[0068] It should be noted that the critical speed range of the steam turbine is usually 790-995rpm, 1520-1725rpm, 1900-2210rpm, and 2270-2850rpm. When the actual speed is in this range, large vibration may occur. Long-term operation in this range will cause damage to the equipment. It is not in the critical range, that is, the actual speed of the unit is not within the above range. If the difference is greater than 20rpm, the change of the speed setting value is stopped. If the difference is less than or equal to 20rpm, the change of the speed setting value is restored. This means adding a waiting logic outside the critical area on the basis of the braking logic. When the steam turbine speed is not within the critical range, if the speed setting value is greater than the actual speed by 20rpm, the speed setting value stops changing to wait for the actual speed to approach the speed setting value. After it is less than 20rpm, it automatically resumes the change rate before waiting.

[0069] In some embodiments, the steam turbine control method of the solar thermal power plant provided in the embodiments of the present application further includes a bypass control strategy, which may include:

[0070] Get the mid-range door control command;

[0071] Taking the middle gate control command as input, the target feedforward amount is obtained according to the feedforward function;

[0072] The target feedforward amount is added to the output command as the feedforward for the low bypass valve PID control.

[0073] In this implementation, the intermediate valve control command is first acquired. A target feedforward value is then derived using the intermediate valve control command as input based on a feedforward function. Finally, the target feedforward value is added to the output command as feedforward for the low bypass valve PID control. This bypass control strategy rapidly stabilizes the reheat steam pressure, which provides a stable and long-lasting energy source for turbine rotation, thus facilitating speed control.

[0074] It should be noted that the above-mentioned target feedforward amount is obtained according to the feedforward function with the middle regulating valve control instruction as input; superimposing the target feedforward amount as the feedforward of the low bypass valve PID control to the output instruction means that the low bypass valve adds the middle regulating valve instruction feedforward on the basis of controlling the reheat steam pressure. Since the reheater volume is relatively small and the reheat steam parameters are relatively low. Therefore, the reheat steam pressure fluctuation is more affected by the action of the regulating valve than conventional units, and the response speed of the low bypass valve to the reheat steam pressure regulation needs to be accelerated. Therefore, a feedforward control loop is added to the conventional PID control loop based on the feedforward amount obtained by the middle regulating valve control instruction through the feedforward function. The middle regulating valve control instruction is used as input, and the feedforward of the low bypass valve PID control is obtained according to the function. The specific functions correspond to the following:

[0075] Intermediate valve control command (%) 110 100 0 -1 Low bypass feedforward amount (%) 0 0 20 20

[0076] The function in the table above generates the feedforward for the low bypass valve PID control and directly adds it to the output command for rapid response. This ensures stable steam parameters during the run-up, increasing the success rate of the run-up. It also ensures speed stability at a constant speed of 3000 rpm, preventing speed fluctuations caused by reheat steam pressure fluctuations. When the unit is operating under load, the center control valve is fully open, with a center control command of 100%, and the low bypass is fully closed, with a low bypass control command of 0%. When the unit experiences load rejection, the DEH control logic triggers the OPC operation upon receiving the trip signal from the generator output circuit breaker. This rapidly closes the control valve by both setting the control valve command to 0 and by actuating the hard-loop OPC solenoid valve to quickly release EH oil pressure. At this point, the center control valve command is instantly set to 0, and the bypass feedforward command mentioned above changes from 0% (closed) to 20%. This application directly opens the bypass quickly to relieve pressure through the feedforward loop, without waiting for the pressure to rise after the regulating valve is closed. The PID will slowly open the regulating valve according to the pressure deviation calculation to reduce the rising reheat steam pressure. There is no need to set up an override logic and avoid conflicts with the protection logic priority.

[0077] In some embodiments, the method further includes a bypass control strategy, and may further include:

[0078] In the rush mode, the high bypass valve is controlled to adjust the reheat steam cold section pressure;

[0079] After the high discharge check valve is opened, the rush mode is reset and switched to the main steam pressure control mode.

[0080] In this implementation, the bypass control strategy first operates the high-pressure bypass valve in the throttle mode to adjust the reheat steam cold-side pressure. Then, after the high-pressure discharge check valve opens, the throttle mode is reset and the main steam pressure control mode is switched. This allows for fully automated high-pressure bypass regulation and meets the APS startup and shutdown requirements of the unit.

[0081] It should be noted that controlling the high bypass valve to adjust the reheat steam cold section pressure refers to controlling the reheat steam cold section pressure through the high bypass valve. The high bypass valve controls the reheat steam cold section pressure: the high bypass valve adjusts the reheat steam cold section pressure according to the current main steam pressure. The high and medium pressure cylinders are jointly started in a starting mode without the participation of the high exhaust ventilation valve, that is, the high exhaust ventilation valve does not open in normal state during the starting process, and only opens when the steam turbine overheats due to the blast friction generated by the rotation of the medium and the medium in the cylinder. At this time, the steam flow in the high-pressure cylinder is only a very small part of the leakage and hydrophobic condensate, which is theoretically not enough to generate enough power to make the unit rotate, so the actual working part is still the medium and low pressure combined cylinder. The opening and closing of the high-pressure valve has little effect on the main steam pressure. When the high bypass valve is switched to manual mode and maintained at 40% opening, the source of the reheated steam is the high bypass outlet. This application uses the high bypass valve to assist in regulating the reheated steam pressure and sets the flushing mode. At this time, the high bypass valve regulates the reheated steam cold section pressure. The flushing mode is automatically reset after the high discharge check valve is opened. At this time, the high bypass valve will automatically switch to regulating the main steam pressure and gradually reduce the steam flow through the bypass system.

[0082] In some embodiments, after the high pressure exhaust check valve is opened and the rush mode is reset and the main steam pressure control mode is switched, the following steps may also be included:

[0083] Monitor the exhaust temperature of high-pressure cylinder;

[0084] When the high-pressure cylinder exhaust temperature is lower than the target temperature threshold, the high bypass control instruction is locked.

[0085] In this implementation, after the HPD check valve opens, the reverse run mode is reset and the HPB valve is switched to main steam pressure control mode. The HPD exhaust temperature is monitored. When the HPD exhaust temperature falls below the target temperature threshold, the HPB control command is locked. This prevents salt freezing in the reheater, reduces the chances of turbine overspeed and significant speed fluctuations, and improves the operational stability of the CSP unit.

[0086] It should be noted that the main steam experiences an enthalpy drop, meaning the steam temperature decreases, whether passing through the high-pressure bypass or high-pressure cylinder. Initially, due to low main steam parameters and incomplete warming of the high-pressure exhaust pipe section, the high-pressure exhaust steam parameters after performing work in the high-pressure cylinder may drop below 260°C, the freezing point of binary molten salt. Direct entry into the reheater may cause the molten salt in the reheater to freeze. However, the steam after the high-pressure bypass valve only experiences the throttling effect of the high-pressure bypass valve, resulting in a smaller temperature drop. Therefore, while increasing the main steam parameters by increasing temperature and pressure, it is necessary to maintain the mixing ratio of the steam after the high-pressure bypass valve to raise the cold reheat steam temperature and prevent salt freezing in the reheater. Therefore, when the exhaust temperature is low, the high-pressure bypass valve needs to be closed to prevent further closure of the high-pressure bypass valve, which would lower the steam temperature after the high-pressure bypass. This lower steam temperature after the high-pressure bypass valve would further exacerbate the low cold reheat steam temperature and cause the molten salt to solidify and freeze.

[0087] In some embodiments, the method further includes a high-voltage bypass control strategy, which may include:

[0088] Get the current main steam pressure value of the steam turbine;

[0089] In the rush mode, the output of the high bypass valve PID control is limited according to the current main steam pressure value of the turbine.

[0090] In this implementation, the current main steam pressure of the turbine is first obtained, and then the output of the high bypass valve PID control is limited based on this current main steam pressure. This prevents low bypass steam shutoff and overpressure, reduces the probability of turbine overspeed and large speed fluctuations, and further improves the operational stability of the CSP unit.

[0091] It should be noted that the output of the high bypass valve PID control is limited according to the current main steam pressure value of the steam turbine. This means that the PID output is limited according to the current main steam pressure to prevent low bypass steam shut-off and overpressure. The specific function is as follows:

[0092] Main steam pressure (after inertia) MPa 4 5.5 15 18 High bypass valve output high limit (%) 60 60 30 30 High bypass valve output low limit 40 40 15 15

[0093] In summary, this application utilizes both a speed control strategy and a bypass control strategy to control the steam turbine unit, improving the accuracy of turbine speed regulation, reducing the likelihood of turbine overspeed and significant speed fluctuations, and enhancing the operational stability of the solar thermal unit. This approach achieves the desired speed control effect, meeting speed control requirements for run-up, speed increase, friction check, over-criticality, a constant speed of 3000 rpm, and synchronization at the required ramp rate, without causing overspeed or significant speed fluctuations.

[0094] In addition, the bypass control strategy can quickly stabilize the reheated steam pressure, and the stable reheated steam pressure can make the energy source for rotating the steam turbine stable and persistent, and thus the speed control is more favorable. The one-key starting (APS) of the unit includes the automatic turbine starting (ATC), that is, the whole process of automatically starting the steam turbine from the static state to the grid connection is automatically completed under the program control. The above control strategy greatly improves the speed regulation effect of the unit from the static state to the speed of 3000 rpm, and it is difficult to overspeed and the phenomenon of long-term synchronization failure. The overspeed and synchronization failure will cause the ATC starting failure. That is, the improvement of the speed regulation effect greatly improves the success rate of the ATC starting.

[0095] Based on the light-thermal unit speed control method provided in the above embodiments, correspondingly, the application also relates to a steam turbine control system of a light-thermal unit, which comprises a control host.

[0096] The application also relates to a power plant comprising a light-thermal unit and a control host, wherein the control host controls the steam turbine of the light-thermal unit by the light-thermal unit steam turbine control method provided in the above embodiments.

[0097] Figure 2 The hardware structure schematic diagram of the electronic device provided in the embodiments of the application is shown.

[0098] The electronic device can include a processor 201 and a memory 202 storing computer program instructions.

[0099] Specifically, the processor 201 can include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the application.

[0100] The memory 202 can include a mass storage for data or instructions. For example, but not limited to, the memory 202 can include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of the above. In a suitable case, the memory 202 can include a removable or non-removable (or fixed) medium. In a suitable case, the memory 202 can be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 202 is a non-volatile solid-state memory.

[0101] In some embodiments, the memory 202 may include read-only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. Thus, generally, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0102] The processor 201 reads and executes computer program instructions stored in the memory 202 to implement any one of the CSP unit coordinated control methods in the above embodiments.

[0103] In one example, the electronic device may further include a communication interface 203 and a bus 210. Figure 2 As shown, the processor 201, the memory 202, and the communication interface 203 are connected via a bus 210 and communicate with each other.

[0104] The communication interface 203 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0105] Bus 210 includes hardware, software or both, and the components of online data flow metering equipment are coupled to each other. For example, but not limitation, bus can include accelerated graphics port (AGP) or other graphics bus, enhanced industry standard architecture (EISA) bus, front side bus (FSB), hypertransport (HT) interconnection, industry standard architecture (ISA) bus, infinite bandwidth interconnection, low pin count (LPC) bus, memory bus, micro channel architecture (MCA) bus, peripheral component interconnection (PCI) bus, PCI-Express (PCI-X) bus, serial advanced technology attachment (SATA) bus, video electronics standard association local (VLB) bus or other suitable bus or two or more of these combinations. In appropriate cases, bus 210 can include one or more buses. Although the present application embodiment describes and shows a specific bus, the application considers any suitable bus or interconnection.

[0106] It should be understood that the present application is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and illustrated as examples. However, the method process of the present application is not limited to the specific steps described and illustrated. Those skilled in the art can make various changes, modifications, and additions, or change the order of the steps after understanding the spirit of the present application.

[0107] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memories, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0108] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps. In other words, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0109] Aspects of the present disclosure have been described above with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the function / action specified in one or more boxes of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor or a field programmable logic circuit. It is also understood that each box in the block diagram and / or flowchart and the combination of the boxes in the block diagram and / or flowchart can also be implemented by dedicated hardware that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0110] The above description is only a specific embodiment of the present application. Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the scope of protection of the present application.

Claims

1. A method for controlling a steam turbine of a solar thermal power plant, characterized in that: Used for joint starting of high and medium pressure cylinders of a CSP unit, including a speed control strategy, the speed control strategy includes: Get the speed setting value change rate setting value of the steam turbine; The set value of the speed set value change rate is used as the input of the integral time generating function of the variable parameter PID control to realize the variable parameter PID control of the turbine speed.

2. The steam turbine control method of a solar thermal power plant according to claim 1, characterized in that: The speed control strategy further includes: Obtain the speed set value, actual speed value and target deviation threshold; Calculating a first deviation value according to the speed setting value and the actual speed value, wherein the first deviation value is the difference between the speed setting value and the actual speed value; When the first deviation value is greater than the target deviation threshold, a first integral separation control signal is generated, which is used to instruct the output of the variable parameter PID to stop superimposing the integral operation increment until the first deviation value is less than or equal to the target deviation threshold.

3. The steam turbine control method of a solar thermal power plant according to claim 1, characterized in that: The speed control strategy further includes: Obtain the turbine speed and determine whether the turbine speed is in the speed-up stage or the speed-constant stage; During the speed-up phase, PID control of the turbine speed is performed using a first PID control parameter, wherein the first PID control parameter is used to indicate a PID control strategy based on proportional action; In the constant speed stage, PID control of the turbine speed is performed by using a second PID control parameter, wherein the second PID control parameter is used to indicate a PID control strategy based on a proportional-integral comprehensive effect.

4. The steam turbine control method of a solar thermal power plant according to claim 1, characterized in that: The speed control strategy further includes: Obtain the turbine speed and determine whether the turbine speed is within the critical range; When the turbine speed is not within the critical range, the difference between the turbine speed setting value and the actual speed value is calculated. If the difference is greater than 20rpm, the change of the speed setting value is stopped. If the difference is less than or equal to 20rpm, the change of the speed setting value is resumed.

5. The steam turbine control method of a solar thermal power plant according to claim 1, characterized in that: The method further includes a bypass control strategy, the bypass control strategy comprising: Get the mid-range door control command; Taking the middle gate control command as input, the target feedforward amount is obtained according to the feedforward function; The target feedforward amount is added to the output command as the feedforward for the low bypass valve PID control.

6. The steam turbine control method of a solar thermal power plant according to claim 1, characterized in that: The method further includes a bypass control strategy, the bypass control strategy comprising: In the rush mode, the high bypass valve is controlled to adjust the reheat steam cold section pressure; After the high discharge check valve is opened, the rush mode is reset and switched to the main steam pressure control mode.

7. The steam turbine control method of a solar thermal power plant according to claim 6, characterized in that: After the high pressure discharge check valve is opened and the rush mode is reset and switched to the main steam pressure control mode, the method further includes: Monitor the exhaust temperature of high-pressure cylinder; When the high-pressure cylinder exhaust temperature is lower than the target temperature threshold, the high bypass control instruction is locked.

8. The steam turbine control method of a solar thermal power plant according to claim 1, characterized in that: The method further includes a bypass control strategy, the bypass control strategy comprising: In the start-up mode, obtain the current main steam pressure value of the turbine; The output of the high bypass valve PID control is limited according to the current main steam pressure value of the turbine.

9. A steam turbine control system for a solar thermal power plant, characterized in that: include: A control host, wherein the control host realizes steam turbine control of the solar thermal power plant through the steam turbine control method of the solar thermal power plant according to any one of claims 1 to 8.

10. A power plant, characterized in that: The invention comprises a solar thermal power unit and a control host, wherein the control host controls the steam turbine of the solar thermal power unit by using the steam turbine control method of the solar thermal power unit according to any one of claims 1 to 8.

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