Steam turbine speed regulation method and system based on small frequency difference compensation

Abstract

The invention provides a turbine speed regulation method and system based on small frequency difference compensation, and the method comprises the steps: obtaining the actual rotating speed and the given rotating speed of a target turbine, and obtaining the rotating speed difference according to the actual rotating speed and the given rotating speed; generating a rotating speed difference signal according to the rotating speed difference, and inputting the rotating speed signal into an improved thermal power generating unit speed regulation system model for simulation to obtain a compensated valve regulation instruction; and adjusting the valve opening of the steam turbine according to the compensated valve adjusting instruction. According to the method, the small frequency difference compensation loop is introduced, so that the valve adjusting instruction curve obtained by the simulation model is more accurate, and more accurate data is provided for suppressing low-frequency oscillation of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbine speed regulation, and in particular to a steam turbine speed regulation method and system based on small frequency difference compensation. Background Art

[0002] Due to the large-scale development of renewable energy and the integration of wind power, photovoltaics, and energy storage into the grid, as well as the introduction of a large number of new power electronic devices, the power grid has exhibited low inertia and weak damping, resulting in poor stability. This has also led to changes in the control foundations and operating mechanisms of the power system. Renewable energy generation is characterized by randomness, intermittency, and volatility. When the grid experiences sudden load changes or other conditions that cause grid oscillations, it is difficult to stabilize, and may even persist, leading to serious consequences.

[0003] Current research on low-frequency oscillations in power units relies primarily on simulation and analysis of typical speed control systems. The speed control system parameter optimization processes involved in these studies can adversely affect the unit's frequency response performance. Furthermore, thermal power units operate under highly variable conditions, and numerous factors can induce low-frequency oscillations on the prime mover side. Parameters tuned based on a single operating condition are unlikely to achieve the desired performance. Consequently, the speed control system parameter optimization processes involved in these studies are unable to effectively suppress low-frequency oscillations under a wide range of operating conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a steam turbine speed control method and system based on small frequency difference compensation, aiming to solve the problem that the parameters adjusted according to a single operating condition in traditional technology are difficult to show the expected performance and cannot effectively suppress low-frequency oscillations under various operating conditions.

[0005] In a first aspect, the present invention provides a steam turbine speed control method based on small frequency difference compensation, the method comprising:

[0006] The actual speed and the given speed of the target steam turbine are obtained, and the speed difference is obtained according to the actual speed and the given speed, specifically:

[0007] Δω=ω ref -ω;

[0008] Among them, ω is the actual speed, ω ref is the given speed, Δω is the speed difference;

[0009] generating a speed difference signal according to the speed difference, and inputting the speed signal into an improved thermal power unit speed regulation system model for simulation to obtain a compensated valve regulating instruction;

[0010] The turbine valve opening is adjusted according to the compensated valve control instruction.

[0011] Furthermore, the steps of constructing the improved thermal power unit speed control system model include:

[0012] Obtain parameter data of on-site speed control system of thermal power units;

[0013] A thermal power unit speed regulation system model is established based on the parameter data, wherein the regulation system in the thermal power unit speed regulation system model is composed of a differential controller, a load controller, and a regulating stage pressure controller, and the control mode is regulating stage pressure control, speed differential control, and differential feedforward load control;

[0014] Add pre-built load small frequency difference compensation loop and valve position small frequency difference compensation loop to the speed differential control and differential feedforward load control.

[0015] Furthermore, the step of generating a speed difference signal according to the speed difference, and inputting the speed signal into an improved thermal power unit speed control system model for simulation to obtain a compensated valve regulating instruction includes:

[0016] The frequency difference signal obtained after the speed difference signal passes through the digital-to-analog conversion link is sent to the load small frequency difference compensation circuit and the valve position small frequency difference compensation circuit respectively, so that the load small frequency difference compensation circuit acts on the load value, and the valve position small frequency difference compensation circuit acts on the valve position value, thereby obtaining the load target value and the valve position target value.

[0017] Furthermore, the mathematical model expression of the load small frequency difference compensation loop is:

[0018]

[0019] Among them, F P (Δf) represents the frequency difference-load compensation value function, Δf represents the frequency difference signal, f1 represents the first preset small frequency difference, P1 represents the frequency regulation load value converted from Δf by the adjustment coefficient, P1 = Δf·K1, K1 represents the load adjustment coefficient, K P Indicates the first compensation coefficient.

[0020] Furthermore, the mathematical model expression of the valve position small frequency difference compensation loop is:

[0021]

[0022] Among them, F G (Δf) represents the frequency difference-valve position compensation value function, f2 represents the second preset small frequency difference, G1 represents the frequency-modulated valve position value converted from Δf by the adjustment coefficient, G1=Δf·K2, K2 represents the valve position adjustment coefficient, K G Indicates the second compensation coefficient.

[0023] Furthermore, the load target value and valve position target value are calculated according to the following formula:

[0024] P s=P0+P1+F P (Δf)

[0025] G s =G0+G1+F G (Δf);

[0026] Among them, P s is the load target value, P0 is the initial load before load change, G s is the valve position target value, and G0 is the initial valve position before the valve position changes.

[0027] In a second aspect, the present invention provides a steam turbine speed control system based on small frequency difference compensation, the system comprising:

[0028] The speed difference acquisition module is used to obtain the actual speed and the given speed of the target steam turbine, and obtain the speed difference according to the actual speed and the given speed, specifically:

[0029] Δω=ω ref -ω;

[0030] Among them, ω is the actual speed, ω ref is the given speed, Δω is the speed difference;

[0031] a simulation module, configured to generate a speed difference signal according to the speed difference, and input the speed signal into an improved thermal power unit speed regulation system model for simulation to obtain a compensated valve regulating instruction;

[0032] The speed adjustment module is used to adjust the turbine valve opening according to the compensated valve adjustment instruction.

[0033] In a third aspect, the present invention provides a storage medium storing one or more programs, which, when executed by a processor, implement the above-mentioned steam turbine speed control method based on small frequency difference compensation.

[0034] In a fourth aspect, the present invention provides an electronic device, comprising a memory and a processor, wherein:

[0035] The memory is used to store computer programs;

[0036] When the processor is used to execute the computer program stored in the memory, the above-mentioned steam turbine speed regulation method based on small frequency difference compensation is implemented.

[0037] In summary, the present invention proposes a steam turbine speed control method based on small frequency difference compensation. By adding a load small frequency difference compensation loop and a valve position small frequency difference compensation loop to the thermal power unit speed control system model to compensate for the adjustment coefficient, the model with the small frequency difference compensation loop introduced is simulated to obtain a compensated valve control instruction. The turbine valve opening is adjusted according to the compensated valve control instruction to control the main steam flow and achieve steam turbine speed control. By introducing the small frequency difference compensation loop, the present invention makes the valve control instruction curve obtained by the simulation model more accurate, providing more accurate data for suppressing low-frequency oscillations of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of a steam turbine speed control method based on small frequency difference compensation proposed in one embodiment of the present invention;

[0039] Figure 2 Schematic diagram of an improved thermal power unit speed regulation system model in one embodiment of the present invention;

[0040] Figure 3 Schematic diagram of a load small frequency difference compensation circuit in one embodiment of the present invention;

[0041] Figure 4 Schematic diagram of a valve position small frequency difference compensation circuit in one embodiment of the present invention;

[0042] Figure 5 is a schematic diagram of a rotation speed difference signal in one embodiment of the present invention;

[0043] Figure 6 Schematic diagram of a valve adjustment command curve in one embodiment of the present invention;

[0044] Figure 7 This is a structural diagram of a steam turbine speed control system based on small frequency difference compensation proposed in one embodiment of the present invention.

[0045] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the invention belongs. The words "including" and similar words used in this article mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0047] like Figure 1 As shown, an embodiment of the present invention provides a steam turbine speed control method based on small frequency difference compensation, the method comprising steps S101 to S103, wherein:

[0048] Step S101: obtaining an actual speed and a given speed of a target steam turbine, and obtaining a speed difference according to the actual speed and the given speed;

[0049] It should be noted that, in some embodiments, the rotational speed difference is calculated according to the following formula:

[0050] Δω=ω ref -ω;

[0051] Among them, ω is the actual speed, ω ref is the given speed, and Δω is the speed difference.

[0052] The load change is represented by the change of speed, and the slip signal Δω is given automatically. The model is verified by the actual low-frequency oscillation data of the unit. A signal is given to indicate that a slip signal exists within a certain period of time. The given slip value is low enough to make the small frequency difference compensation loop effective. The specific signal is shown in Figure 5 (The horizontal axis is time in seconds, and the vertical axis is frequency in Hertz).

[0053] Step S102: generating a speed difference signal according to the speed difference, and inputting the speed difference signal into an improved thermal power unit speed control system model for simulation to obtain a compensated valve control instruction;

[0054] It should be pointed out that the process of constructing an improved thermal power unit speed control system model is as follows: obtaining parameter data of the thermal power unit on-site speed control system; establishing a thermal power unit speed control system model based on the parameter data, wherein the control system in the thermal power unit speed control system model is composed of a differential controller, a load controller, and a regulating stage pressure controller, and the control mode is regulating stage pressure control, speed differential control, and differential feedforward load control; adding a pre-built load small frequency difference compensation loop and a valve position small frequency difference compensation loop to the speed differential control and differential feedforward load control.

[0055] Specifically, first, the parameters of the current operating data of a 350MW thermal power unit on-site speed control system are obtained and designed in combination with the typical thermal power unit speed control system model. Including the time constants T1 and T R1 、T R2 、T C 、T D 、T I , the delay T of each action component W1 、T W2 、T W2pid 、T P 、T L , adjustment coefficients K1, K2, and current PID control parameter K P , K I , K D These are used as the assignment of parameters to the classic speed regulation model that serves as the basis for development, in order to simulate the operating state of a thermal power unit in an actual project.

[0056] Secondly, the speed control system model of the thermal power unit is modeled based on the various parameter data obtained. The control system in the speed control system model of the thermal power unit consists of a differential controller, a load controller, and a regulating stage pressure controller. It can switch between three control modes, namely regulating stage pressure control, speed differential control, and load control with differential feedforward.

[0057] Then, a load small frequency difference compensation loop and a valve position small frequency difference compensation loop are added to the classic speed regulation model's speed differential control and differential feedback control scheme. The small frequency difference compensation strategy is a control strategy incorporated into the classic speed regulation system to improve the primary frequency regulation's small frequency difference response capability during actual operation of thermal power units. The slip signal Δω undergoes digital-to-analog conversion and is fed into the small frequency difference compensation loop as the frequency difference signal Δf.

[0058] The load small frequency difference compensation loop and valve position small frequency difference compensation loop act on the load value and valve position value respectively, as additional compensation for the adjustment coefficient and K2. The adjustment coefficient is used to reasonably distribute the load among the generators when the load changes. In order to obtain the load target value and valve position target value, the model with the small frequency difference compensation loop is as follows: Figure 2 shown. Figure 2 The compensation circuit on the left is the load small frequency difference compensation circuit. Figure 2 The compensation circuit on the right is the valve position small frequency difference compensation circuit.

[0059] In addition, after obtaining the speed difference, the frequency difference signal obtained after the speed difference signal passes through the digital-to-analog conversion link is sent to the load small frequency difference compensation circuit and the valve position small frequency difference compensation circuit respectively, so that the load small frequency difference compensation circuit acts on the load value, and the valve position small frequency difference compensation circuit acts on the valve position value, thereby obtaining the load target value and the valve position target value.

[0060] In some embodiments, the load target value and the valve position target value are calculated according to the following formula:

[0061] P s =P0+P1+F P (Δf)

[0062] G s =G0+G1+F G (Δf);

[0063] Among them, P s is the load target value, P0 is the initial load before load change, G s is the valve position target value, and G0 is the initial valve position before the valve position changes.

[0064] In addition, in some embodiments, the mathematical model expression of the load small frequency difference compensation loop is:

[0065]

[0066] Among them, F P (Δf) represents the frequency difference-load compensation value function, Δf represents the frequency difference signal, f1 represents the first preset small frequency difference, P1 represents the frequency regulation load value converted from Δf by the adjustment coefficient, P1 = Δf·K1, K1 represents the load adjustment coefficient, K P Indicates the first compensation coefficient.

[0067] For example, Figure 3 As shown, when the absolute value of the frequency difference signal Δf is less than f1, a compensation loop is formed, corresponding to Figure 3 When the absolute value of the frequency difference signal Δf is greater than or equal to f1, Figure 3 The switch in the box is connected to the contact corresponding to 1 and K P The corresponding contacts are disconnected.

[0068] In addition, in some embodiments, the mathematical model expression of the valve position small frequency difference compensation loop is:

[0069]

[0070] Among them, F G (Δf) represents the frequency difference-valve position compensation value function, f2 represents the second preset small frequency difference, G1 represents the frequency-modulated valve position value converted from Δf by the adjustment coefficient, G1=Δf·K2, K2 represents the valve position adjustment coefficient, K G Indicates the second compensation coefficient.

[0071] For example, when the absolute value of the frequency difference signal Δf is less than f2, a compensation loop is formed, corresponding to Figure 4 When the absolute value of the frequency difference signal Δf is greater than or equal to f2, Figure 4 The switch in the box is connected to the contact corresponding to 1 and K G The corresponding contacts are disconnected.

[0072] It can be seen that when the small frequency difference compensation circuit is used, the relationship between the absolute value of the frequency difference Δf and the given small frequency difference values ​​f1 and f2 is judged to determine whether small frequency difference compensation is needed. When compensation is used, the compensation coefficient K is used. P , K G Compensation is performed using frequency difference-load and frequency difference-valve position methods respectively.

[0073] Step S103: adjusting the turbine valve opening according to the compensated valve regulating instruction.

[0074] It should be noted that by applying the speed difference signal to the original classic model and the low-frequency oscillation model with the addition of small frequency difference compensation and valve flow module, setting the sampling time to 0.02s, recording the corresponding valve command curve from 0s to 600s, and intercepting the part that can clearly show the difference in the curve, such as Figure 6 shown.

[0075] Figure 6 It can be seen that the introduction of the small frequency difference compensation loop can better reflect the enhanced local frequency modulation, and the model simulation curve clearly shows the compensation effect of the throttle command. In contrast, the typical speed regulation model uses a fixed differential coefficient, which cannot reflect the enhanced local frequency modulation capability of small frequency difference. This leads to a significant difference between the simulation results of the typical model and the actual control strategy curve, indicating that the simulation results of the improved model are more practical reference value.

[0076] In summary, based on the improved small frequency difference compensation model for the speed regulation system, simulation analysis methods were used to obtain the system's control instructions and oscillation curves. Significant differences were observed compared to the classic model, verifying the authenticity of this control model in simulating on-site unit operation and enabling more accurate replication of additional control strategies in the field. This can then be used to formulate control strategies to mitigate the actual impact of additional control strategies on system stability, thereby suppressing system oscillations.

[0077] Furthermore, the present invention uses a low-frequency oscillation model incorporating a small frequency difference compensation loop to simulate the actual operation of a thermal power unit. The simulation curves reveal the difference between the response curves of the low-frequency oscillation model and the classical model, demonstrating that the simulation curves of the improved model better reflect actual conditions and the impact of the unit's actual control strategy on control capabilities. This provides more accurate data for subsequent control strategy design and optimization based on simulation results that are more realistic, thereby better maintaining system stability and suppressing the unit's low-frequency oscillations.

[0078] The variables involved in the present invention are described as follows:

[0079] T1 represents the time constant of the speed differential adjustment link, T R1 Indicates the time constant of the pressure controller, T R2 Indicates the load controller time constant, T W1 Indicates the delay of the slip speed regulation link, T P Indicates the delay of the pressure control link, T L Indicates the delay of the load control link, T C Indicates the response time constant of the oil motor throttle valve opening, T D Indicates the response time constant of the oil motor throttle valve closing, T W2 Indicates the delay of the load control feedforward control mode, T W2pid Indicates the delay of load PID control mode, K1 indicates the load adjustment coefficient, K2 indicates the valve position adjustment coefficient, K P Represents the proportionality coefficient, K I Indicates the integral coefficient, K D Indicates the differential coefficient, N indicates the control mode selection parameter, P E Indicates the main steam pressure, P M1 Indicates load feedback, P CV Indicates the tuning command.

[0080] like Figure 7 As shown, an embodiment of the present invention further provides a steam turbine speed control system based on small frequency difference compensation, the system comprising:

[0081] The speed difference acquisition module 10 is used to obtain the actual speed and the given speed of the target steam turbine, and obtain the speed difference according to the actual speed and the given speed, specifically:

[0082] Δω=ω ref -ω;

[0083] Among them, ω is the actual speed, ω ref is the given speed, Δω is the speed difference;

[0084] A simulation module 20 is configured to generate a speed difference signal according to the speed difference, and input the speed signal into an improved thermal power unit speed control system model for simulation to obtain a compensated valve control instruction;

[0085] The speed adjustment module 30 is used to adjust the opening of the steam turbine valve according to the compensated valve adjustment instruction.

[0086] On the other hand, the present invention further proposes a storage medium on which one or more programs are stored. When the programs are executed by a processor, the above-mentioned steam turbine speed control method based on small frequency difference compensation is implemented.

[0087] On the other hand, the present invention also proposes an electronic device, including a memory and a processor, wherein the memory is used to store computer programs, and the processor is used to execute the computer programs stored in the memory to implement the above-mentioned turbine speed control method based on small frequency difference compensation.

[0088] Those skilled in the art will appreciate that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device), or in conjunction with such instruction execution system, apparatus, or device. For purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transmit a program for use by an instruction execution system, apparatus, or device, or in conjunction with such instruction execution system, apparatus, or device.

[0089] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0090] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement the hardware: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0091] While the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations of these embodiments are possible. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the claims. Furthermore, the invention described herein is susceptible to other embodiments and may be practiced or implemented in a variety of ways.

Claims

1. A steam turbine speed control method based on small frequency difference compensation, characterized in that: The method comprises: The actual speed and the given speed of the target steam turbine are obtained, and the speed difference is obtained according to the actual speed and the given speed, specifically: Give = oh ref -oh; Among them, ω is the actual speed, ω ref is the given speed, Δω is the speed difference; generating a speed difference signal according to the speed difference, and inputting the speed signal into an improved thermal power unit speed regulation system model for simulation to obtain a compensated valve regulating instruction; The turbine valve opening is adjusted according to the compensated valve control instruction.

2. The steam turbine speed control method based on small frequency difference compensation according to claim 1, characterized in that: The steps to construct the improved thermal power unit speed control system model include: Obtain parameter data of on-site speed control system of thermal power units; A thermal power unit speed regulation system model is established based on the parameter data, wherein the regulation system in the thermal power unit speed regulation system model is composed of a differential controller, a load controller, and a regulating stage pressure controller, and the control mode is regulating stage pressure control, speed differential control, and differential feedforward load control; Add pre-built load small frequency difference compensation loop and valve position small frequency difference compensation loop to the speed differential control and differential feedforward load control.

3. The steam turbine speed control method based on small frequency difference compensation according to claim 2, characterized in that: The step of generating a speed difference signal according to the speed difference, and inputting the speed signal into an improved thermal power unit speed control system model for simulation to obtain a compensated valve regulating instruction includes: The frequency difference signal obtained after the speed difference signal passes through the digital-to-analog conversion link is sent to the load small frequency difference compensation circuit and the valve position small frequency difference compensation circuit respectively, so that the load small frequency difference compensation circuit acts on the load value, and the valve position small frequency difference compensation circuit acts on the valve position value, thereby obtaining the load target value and the valve position target value.

4. The steam turbine speed control method based on small frequency difference compensation according to claim 3, characterized in that: The mathematical model expression of the load small frequency difference compensation loop is: Among them, F P (Δf) represents the frequency difference-load compensation value function, Δf represents the frequency difference signal, f1 represents the first preset small frequency difference, P1 represents the frequency regulation load value converted from Δf by the adjustment coefficient, P1 = Δf·K1, K1 represents the load adjustment coefficient, K P Indicates the first compensation coefficient.

5. The steam turbine speed control method based on small frequency difference compensation according to claim 4, characterized in that: The mathematical model expression of the valve position small frequency difference compensation loop is: Among them, F G (Δf) represents the frequency difference-valve position compensation value function, f2 represents the second preset small frequency difference, G1 represents the frequency-modulated valve position value converted from Δf by the adjustment coefficient, G1=Δf·K2, K2 represents the valve position adjustment coefficient, K G Indicates the second compensation coefficient.

6. The steam turbine speed control method based on small frequency difference compensation according to claim 5, characterized in that: The load target value and valve position target value are calculated according to the following formula: P s =P0+P1+F P (Δf) G s =G0+G1+F G (Δf); Among them, P s is the load target value, P0 is the initial load before load change, G s is the valve position target value, and G0 is the initial valve position before the valve position changes.

7. A steam turbine speed control system based on small frequency difference compensation, characterized in that: The system comprises: The speed difference acquisition module is used to obtain the actual speed and the given speed of the target steam turbine, and obtain the speed difference according to the actual speed and the given speed, specifically: Give = oh ref -oh; Among them, ω is the actual speed, ω ref is the given speed, Δω is the speed difference; a simulation module, configured to generate a speed difference signal according to the speed difference, and input the speed signal into an improved thermal power unit speed regulation system model for simulation to obtain a compensated valve regulating instruction; The speed adjustment module is used to adjust the turbine valve opening according to the compensated valve adjustment instruction.

8. A storage medium, characterized in that: The storage medium stores one or more programs, which, when executed by the processor, implement the steam turbine speed control method based on small frequency difference compensation as described in any one of claims 1 to 6.

9. An electronic device comprising a memory and a processor, wherein: The memory is used to store computer programs; When the processor is used to execute the computer program stored in the memory, it implements the steam turbine speed control method based on small frequency difference compensation as described in any one of claims 1 to 6.

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