A control method for primary frequency modulation in a thermal power unit

Abstract

This application discloses a control method for primary frequency regulation in a thermal power unit. The method includes: after receiving primary frequency regulation control information, determining the control mode for primary frequency regulation; obtaining a correction strategy for the control mode; correcting the action value corresponding to the primary frequency regulation control information according to the correction strategy; and performing a primary frequency regulation operation according to the corrected primary frequency regulation action value.

Description

Technical Field

[0001] This application relates to the field of information processing, and more particularly to a control method for primary frequency regulation in a thermal power unit. Background Technology

[0002] Primary frequency regulation refers to the function of generating units that automatically increase or decrease power in response to grid frequency changes when the grid frequency exceeds the prescribed normal range. This achieves a new equilibrium and limits grid frequency fluctuations within a certain range. Primary frequency regulation is a crucial means of maintaining grid stability. Compared to other frequency regulation methods, its most significant characteristic is its speed. When the grid frequency exceeds the dead zone, primary frequency regulation activates immediately for rapid response and adjustment. However, primary frequency regulation also has certain limitations, as rapid response can cause significant disturbances to the power supply side.

[0003] With the changing times and technological advancements, the goals of "carbon neutrality and peak carbon emissions" have been proposed, leading to continuous changes in the power structure. The proportion of new energy sources is constantly increasing, while the proportion of thermal power is declining year by year. While environmental and low-carbon indicators are improving, interference factors affecting the power grid frequency are also increasing, placing higher demands on the stability of the power grid frequency. The characteristics of thermal power units determine that their frequency regulation and peak-shaving functions cannot be replaced in the short term. Especially for primary frequency regulation, new energy sources cannot adjust power upwards, and adjusting downwards would result in energy loss. Therefore, primary frequency regulation of thermal power units is extremely important.

[0004] While the requirements for thermal power units vary across power grids, they all have clear requirements for primary frequency regulation and corresponding reward and assessment mechanisms. The evaluation criteria for primary frequency regulation generally include response time, action amplitude, and integral power. Response time requires the active power of the thermal power unit to change in the correct direction within a specified time. Action amplitude requires the power change to reach a certain value within a specified time. Integral power refers to the increase or decrease in power generation within a certain range throughout the primary frequency regulation period. The quality of each thermal power plant's primary frequency regulation performance directly impacts its economic benefits. Traditional primary frequency regulation methods are gradually becoming inadequate. Therefore, researching optimization schemes that can effectively improve the primary frequency regulation of power units, while ensuring safe and stable operation, is of great significance.

[0005] In related technologies, the primary frequency regulation strategy for thermal power plants is as follows:

[0006] 1. Generate the primary frequency regulation action function F(x) based on the primary frequency regulation action dead zone, primary frequency regulation action limit and speed unequal rate required by the power grid.

[0007] 2. The generated primary frequency regulation action function is superimposed on the turbine main control PID of the distributed control system (DCS) coordination system, and this function is also superimposed on the open-loop loop and power closed-loop loop of the DEH (Digital Electric-Hydraulic) side.

[0008] 3. When the primary frequency regulation index is poor, the response time of the primary frequency regulation can usually meet the standard because the DEH side has a feedforward function. In most cases, the action amplitude and integral power index are poor. At this time, the primary frequency regulation action function of the DEH side will be adjusted to improve the corresponding index.

[0009] In practical applications, while the above-mentioned frequency regulation strategy is simple to implement, it has several drawbacks. Because thermal power unit regulation is complex and many factors affect unit power, simply modifying a single function can produce different effects under different operating conditions, potentially only effective within a specific range of conditions. Furthermore, this strategy is effective when the DEH (Digital Electro-Hydraulic) control system is in both open-loop and power closed-loop circuits; however, when the DEH is in the pressure loop, primary frequency regulation fails, resulting in incomplete coverage. Summary of the Invention

[0010] To address any of the aforementioned technical problems, this application provides a control method for primary frequency regulation in a thermal power unit.

[0011] To achieve the objectives of the embodiments of this application, the embodiments of this application provide a control method for primary frequency regulation in a thermal power unit, including:

[0012] After receiving the frequency modulation control information, determine the control mode for the frequency modulation.

[0013] Obtain the correction strategy for the control method;

[0014] The action value corresponding to the primary frequency modulation control information is corrected according to the correction strategy;

[0015] Perform a frequency modulation operation based on the corrected frequency modulation action value.

[0016] A storage medium storing a computer program, wherein the computer program is configured to execute the method described above at runtime.

[0017] An electronic device includes a memory and a processor, the memory storing a computer program and the processor being configured to run the computer program to perform the methods described above.

[0018] One of the above technical solutions has the following advantages or beneficial effects:

[0019] By determining the primary frequency regulation control method and correcting the action value corresponding to the primary frequency regulation control information according to the correction strategy of the control method, the primary frequency regulation performance of the unit under all operating conditions is effectively improved.

[0020] Other features and advantages of the embodiments of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the embodiments of this application. The objects and other advantages of the embodiments of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0021] The accompanying drawings are used to provide a further understanding of the technical solutions of the embodiments of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the embodiments of this application and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0022] Figure 1 A flowchart of a primary frequency regulation control method for thermal power units provided in this application embodiment;

[0023] Figure 2 A schematic diagram illustrating the signal processing method of the turbine main control system provided in an embodiment of this application;

[0024] Figure 3 This is a control diagram of the primary frequency modulation operation on the DEH side provided in an embodiment of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0026] In the process of realizing this application, a technical analysis of the relevant technologies was conducted, and the relevant technologies included...

[0027] In response to the aforementioned prominent problems faced by thermal power plants in operation, this application provides a more comprehensive optimization scheme for primary frequency regulation of thermal power units, which can effectively improve the primary frequency regulation performance of the unit under all operating conditions and ensure that the primary frequency regulation of the unit can operate normally under different control loops of the DEH.

[0028] Figure 1 A flowchart illustrating the primary frequency regulation control method in a thermal power unit provided in this application embodiment.

[0029] like Figure 1 As shown, the method includes:

[0030] Step 101: After receiving the primary frequency modulation control information, determine the primary frequency modulation control mode;

[0031] Step 102: Obtain the correction strategy for the control method;

[0032] Step 103: Correct the action value corresponding to the primary frequency modulation control information according to the correction strategy;

[0033] Step 104: Perform a frequency modulation operation based on the corrected frequency modulation action value.

[0034] The method provided in this application embodiment determines the primary frequency regulation control mode and corrects the action value corresponding to the primary frequency regulation control information according to the correction strategy of the control mode, thereby effectively improving the primary frequency regulation performance of the unit under all operating conditions.

[0035] The method provided in the embodiments of this application is described below:

[0036] In one exemplary embodiment, the method further includes:

[0037] When the control mode is CCS mode or open-loop control mode, if a load command including primary frequency regulation control information is received, it is determined whether the load command is a load command acting on the valve position baseline, and the determination result is obtained;

[0038] If the determination result is a load command applied to the valve position baseline, then the frequency modulation control information is deleted from the load command to obtain a new load command;

[0039] Execute the new load command.

[0040] Since the amplitude of the primary frequency regulation action has specific requirements, and the primary frequency regulation action function on the turbine main control side is generated according to the standard, and since the turbine main control is a load closed-loop control, the optimization content does not involve the primary frequency regulation command of the DCS coordinated control.

[0041] Figure 2 This is a schematic diagram illustrating the signal processing method of the turbine main control system provided in an embodiment of this application. Figure 2 As shown, the turbine main control system splits the load command, separating the primary frequency regulation command. The load command entering the PID (proportional, integral, and derivative) is superimposed with the primary frequency regulation, while the load command acting on the valve position baseline does not contain the primary frequency regulation. Since the DEH side already has feedforward quantities for valve action, and the valve position baseline function is also equivalent to a feedforward quantity for the turbine main control, the primary frequency regulation quantity of the valve position baseline is removed to avoid the repeated superposition of feedforward quantities. The turbine main control PID needs to superimpose the primary frequency regulation command to eliminate the deviation after feedforward action, thereby improving the accuracy of integral power.

[0042] After structural optimization, PID parameters can be further optimized. Specifically, the integral action of the PID can be strengthened while maintaining stable regulation. This can improve the speed and stability of load closed-loop control.

[0043] In one exemplary embodiment, the method further includes:

[0044] Determine whether the control method is a power closed-loop control method;

[0045] If the control method is not power closed-loop control, then obtain the correction strategy for the control method.

[0046] After the DEH is connected to the grid, the control methods include open-loop control, power closed-loop control, CCS (Coordinated Control System) control, regulating stage pressure control, and main steam pressure control. Among them, the power closed-loop control directly controls the power, so the frequency regulation command does not need to be corrected in the next cycle.

[0047] Figure 3 This is a control diagram illustrating the primary frequency modulation operation on the DEH side provided in an embodiment of this application. Figure 3 As shown below, the frequency modulation optimization scheme for each control method will be introduced one by one.

[0048] If the control method is the regulating stage pressure method, then calculate the first ratio of the primary frequency regulation action power value to the unit's rated power value; calculate the product of the first ratio and the unit's rated regulating stage pressure to obtain the corrected action value;

[0049] Specifically, the regulating stage pressure is the pressure before the first stage blades of the high-pressure cylinder of the steam turbine, which is also the actual working pressure after throttling by the control valve. Ignoring the influence of the main steam temperature, the regulating stage pressure is directly proportional to the generator power. Therefore, the primary frequency regulation action value of the regulating stage pressure is:

[0050] Primary frequency regulation action value (regulating stage pressure value) = Primary frequency regulation action power value ÷ Unit rated power value × Unit rated regulating stage pressure value

[0051] If the control mode is the main steam pressure mode, then calculate the first ratio between the primary frequency regulation action power value and the unit rated power value; and calculate the first difference between the rated main steam pressure value and the rated main steam pressure value at startup, calculate the product of the first ratio and the first difference to obtain the magnitude of the corrected action value, wherein the adjustment direction of the corrected action value is reversed;

[0052] Specifically, under the same valve opening, the main steam pressure also reflects the turbine's work capacity, but the relationship is not strictly proportional. Moreover, the main steam pressure is upstream of the turbine valves, and its action direction is opposite to that of the regulating stage pressure control. The primary frequency regulation action value of the main steam pressure is determined by the following formula:

[0053] Primary frequency regulation action value (main steam pressure) = -(primary frequency regulation action power ÷ unit rated power × (rated main steam pressure - rated main steam pressure at startup))

[0054] If the control mode is a coordinated control system (CCS) mode or an open-loop control mode, then the correction information of the primary frequency regulation feedforward action value is obtained, wherein the correction information includes the main steam pressure value, the active power load value, and the comprehensive valve position value; the product of the correction information and the primary frequency regulation action power value is calculated to obtain the corrected primary frequency regulation feedforward action value; based on the corrected primary frequency regulation feedforward action value, the corrected primary frequency regulation action value is obtained.

[0055] Specifically, the CCS mode and the open-loop mode actually use the same circuit, only the commands are issued by the DCS and the operator respectively, and the frequency regulation action is the same. In the actual operation of the unit, the CCS mode is the main operating mode. In this mode, the turbine main control performs closed-loop regulation to eliminate deviations, while the DEH side acts as a feedforward to perform step action.

[0056] First, the factors affecting the load value of primary frequency modulation feedforward operation include:

[0057] Main steam pressure indirectly represents steam quality;

[0058] The active power load value, where the operating characteristics of primary frequency regulation are different under different loads, and primary frequency regulation tests are usually carried out in three accurate load ranges of 60%, 75% and 90% to facilitate parameter correction;

[0059] The integrated valve position command is used to correct the flow characteristics of each valve position range, as the flow characteristics of each range cannot be perfectly linear due to the flow characteristics.

[0060] Furthermore, the step of obtaining the correction information for the primary frequency modulation feedforward action value includes:

[0061] Using pre-stored correction functions, the real-time values ​​of the correction parameters for the current main steam pressure, the current active power load, and the current integrated valve position are obtained respectively.

[0062] The correction information is obtained by multiplying the real-time values ​​of all correction parameters.

[0063] The three correction parameters mentioned above are multiplicative.

[0064] Furthermore, the correction of load values ​​and the overall valve position correction also need to take into account the difference between single valves and sequence valves, so five additional functions are needed for correction.

[0065] Single-valve open-loop primary frequency regulation feedforward = primary frequency regulation action power × main steam pressure correction × load correction (single valve) × comprehensive valve position correction (single valve)

[0066] Open-loop primary frequency regulation feedforward in forward valve mode = primary frequency regulation action power × main steam pressure correction × load correction (forward valve) × comprehensive valve position correction (forward valve)

[0067] Furthermore, after obtaining the real-time values ​​of all correction parameters, the method further includes:

[0068] The real-time values ​​of all the correction parameters are locked, and the value of each correction parameter is recalculated when the next frequency modulation operation is performed.

[0069] Since the main steam pressure, load, and overall valve position values ​​will all change after a frequency regulation operation, the corresponding correction function will also fluctuate slightly. For the sake of rigor, these correction parameters will be locked during a frequency regulation operation and recalculated after the operation ends.

[0070] Furthermore, the maximum values ​​of the correction parameters for the main steam pressure, the active power load, and the comprehensive valve position are set separately;

[0071] Once the real-time value of the correction parameter is obtained, it is compared with the maximum value of the corresponding correction parameter. If the real-time value is less than the maximum value of the correction parameter, the correction information is calculated.

[0072] Since only the algorithm parameters need to be modified after the logic framework is built and downloaded, in order to prevent accidental operation and for safety reasons, the final output of each important algorithm block, especially the open-loop mode, needs to be limited.

[0073] The larger the value of the main steam pressure, the smaller the maximum value of the correction parameter; the maximum values ​​of the correction parameters for the active power load value and the comprehensive valve position value are both less than or equal to 1.

[0074] The primary frequency regulation logic framework on the DEH side performs limit operations on the output. Specifically, the main steam pressure correction function, active power function, and integrated valve position function can be filled in first, with a default output of 1.

[0075] For example, when the unit is operating normally, the main steam pressure will generally not be lower than 50% of the rated pressure. Therefore, a correction factor of 2 can be set for 0 pressure as the upper limit, a correction factor of 1.5-1.8 can be set for 50% of the rated pressure, a correction factor of 1 can be set for 100% of the rated pressure, and a correction factor of 0.8 can be set for 125% of the rated pressure as the upper limit.

[0076] Optionally, the method further includes:

[0077] When the control loop in operation switches from the first control loop to the second control loop, the difference between the tracking value of the first control loop and the primary frequency modulation action value currently used by the first control loop is calculated to obtain the second difference.

[0078] When switching back to the first control loop, a frequency modulation operation of the first control loop is performed based on the second difference.

[0079] To achieve seamless switching between loops, this invention also optimizes the tracking loop. The tracking value of each loop is reduced by the current frequency modulation action value of that loop. In this way, when the control mode is switched during a frequency modulation action, the frequency modulation action value is still present. When the frequency modulation ends, it will also return to the normal value.

[0080] In summary, the method provided in this application's embodiments has the following advantages:

[0081] 1. Without modifying the main function of the primary frequency regulation action, parameters such as the action amplitude and speed variability are readily apparent.

[0082] 2. Optimize the logic framework of the main control of the steam turbine on the DCS side to prevent repeated and superimposed actions.

[0083] 3. DEH is considered separately in various control modes. Compared with the conventional scheme, it adds a primary frequency regulation action of the pressure loop, which ensures the comprehensiveness of the primary frequency regulation action, and at the same time greatly improves the action accuracy of each loop.

[0084] 4. In both DEH open-loop and CCS modes, valve action is corrected. The valve step action is corrected by the main steam pressure, active power, and overall valve position, which can improve the regulation accuracy under all operating conditions.

[0085] 5. The correction coefficient is locked in a single frequency modulation operation to prevent coefficient fluctuations and improve the rigor of the logic.

[0086] 6. After the logic framework is downloaded, only parameters need to be modified online, eliminating the need for logic download and improving security.

[0087] 7. Strictly limit the upper and lower limits of each circuit output to prevent significant malfunctions due to incorrect parameter modifications.

[0088] 8. Optimize the tracking of each circuit in the DEH to ensure that the circuits can still be switched without disturbance during a single frequency modulation operation.

[0089] This application provides a storage medium storing a computer program, wherein the computer program is configured to execute the method described in any of the preceding descriptions when it runs.

[0090] This application provides an electronic device including a memory and a processor. The memory stores a computer program, and the processor is configured to run the computer program to perform the method described in any of the preceding descriptions.

[0091] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A control method for primary frequency regulation in a thermal power unit, comprising: After receiving the frequency modulation control information, determine the control mode for the frequency modulation. Obtain the correction strategy for the control method; The action value corresponding to the primary frequency modulation control information is corrected according to the correction strategy; Perform a frequency modulation operation based on the corrected frequency modulation action value; The step of correcting the action value corresponding to the primary frequency modulation control information according to the correction strategy includes: If the control method is the regulating stage pressure method, then calculate the first ratio of the primary frequency regulation action power value to the unit's rated power value; calculate the product of the first ratio and the unit's rated regulating stage pressure to obtain the corrected action value; If the control mode is the main steam pressure mode, then calculate the first ratio between the primary frequency regulation action power value and the unit rated power value; and calculate the first difference between the rated main steam pressure value and the rated main steam pressure value at startup, calculate the product of the first ratio and the first difference to obtain the magnitude of the corrected action value, wherein the adjustment direction of the corrected action value is reversed; If the control mode is a coordinated control system (CCS) mode or an open-loop control mode, then the correction information of the primary frequency regulation feedforward action value is obtained, wherein the correction information includes the main steam pressure value, the active power load value, and the comprehensive valve position value; the product of the correction information and the primary frequency regulation action power value is calculated to obtain the corrected primary frequency regulation feedforward action value; based on the corrected primary frequency regulation feedforward action value, the corrected primary frequency regulation action value is obtained.

2. The method according to claim 1, characterized in that, The method further includes: Determine whether the control method is a power closed-loop control method; If the control method is not power closed-loop control, then obtain the correction strategy for the control method.

3. The method according to claim 1, characterized in that, The step of obtaining the correction information for the primary frequency modulation feedforward action value includes: Using pre-stored correction functions, the real-time values ​​of the correction parameters for the current main steam pressure, the current active power load, and the current integrated valve position are obtained respectively. The correction information is obtained by multiplying the real-time values ​​of all correction parameters.

4. The method according to claim 3, characterized in that, The method further includes: The maximum values ​​of the correction parameters for the main steam pressure value, the active power load value, and the comprehensive valve position value are set respectively; wherein the larger the value of the main steam pressure value, the smaller the maximum value of the correction parameter; the maximum values ​​of the correction parameters for the active power load value and the comprehensive valve position value are both less than or equal to 1; Once the real-time value of the correction parameter is obtained, it is compared with the maximum value of the corresponding correction parameter. If the real-time value is less than the maximum value of the correction parameter, the correction information is calculated.

5. The method according to claim 3, characterized in that, After obtaining the real-time values ​​of all correction parameters, the method further includes: The real-time values ​​of all the correction parameters are locked, and the value of each correction parameter is recalculated when the next frequency modulation operation is performed.

6. The method according to claim 1, characterized in that, The method further includes: When the control loop in operation switches from the first control loop to the second control loop, the difference between the tracking value of the first control loop and the primary frequency modulation action value currently used by the first control loop is calculated to obtain the second difference. When switching back to the first control loop, a frequency modulation operation of the first control loop is performed based on the second difference.

7. The method according to claim 1, characterized in that, The method further includes: When the control mode is the coordinated control system (CCS) mode or the open-loop control mode, if a load command including primary frequency modulation control information is received, it is determined whether the load command is a load command that acts on the valve position baseline, and the determination result is obtained. If the determination result is a load command applied to the valve position baseline, then the frequency modulation control information is deleted from the load command to obtain a new load command; Execute the new load command.

8. A storage medium, characterized in that, The storage medium stores a computer program, wherein the computer program is configured to execute the method described in any one of claims 1 to 7 when it is run.

9. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the method as described in any one of claims 1 to 7.

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