System and method for steam turbine frequency modulation and load control of thermal power plant

Abstract

The invention relates to a steam turbine frequency modulation and load control system for a thermal power plant, and the system comprises a rotating speed deviation calculation module which receives a steam turbine rotating speed signal and a steam turbine rated rotating speed signal, and obtains a rotating speed deviation signal through calculation; the positive linear rounding function module receives the rotating speed deviation signal and processes the rotating speed deviation signal to obtain a positive deviation signal; the negative linear rounding function module receives the rotating speed deviation signal and processes the rotating speed deviation signal to obtain a negative deviation signal; the theoretical frequency modulation load calculation module is used for receiving the positive deviation signal and the negative deviation signal, processing and calculating to obtain a theoretical frequency modulation load; the steam turbine control valve PID control module receives the theoretical frequency modulation load signal and the load instruction signal, and calculates and outputs a steam turbine control valve control instruction; the circulating water pump frequency PID control module is used for receiving the theoretical frequency modulation load signal and calculating and outputting a circulating water pump frequency control instruction; the primary frequency modulation action of the unit is assisted through frequency conversion of the circulating water pump, the primary frequency modulation related indexes of the unit in the high-load section are improved, and the unit competitiveness and related benefits are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic control of thermal power generation, and in particular to the technical field of a system for frequency regulation and load control of a steam turbine in a thermal power plant. Background Art

[0002] Grid frequency is an important indicator of the balance between power supply and demand. Primary frequency regulation is an important means of regulating grid frequency, which balances grid frequency by adjusting power generation. The increase in renewable energy generation poses a challenge to the stability of grid frequency, and thermal power needs to participate more in frequency regulation and peak regulation.

[0003] The primary frequency regulation of traditional thermal power units mainly adjusts the power generation by adjusting the opening of the turbine regulating valve. When the unit load is high, the opening of the turbine regulating valve is large, and the regulating valve adjustment margin may be insufficient when the frequency regulation is activated, resulting in slow or no load growth, affecting the frequency regulation effect. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to improve the primary frequency regulation qualification rate and related indicators of the unit when the unit load is high and the turbine regulating valve opening is large.

[0005] In order to solve the above technical problems, a system for frequency regulation and load control of a steam turbine in a thermal power plant is provided according to the present invention, wherein a variable frequency circulating water pump is provided on the steam turbine, wherein the system comprises:

[0006] Steam turbine speed signal module, used to detect steam turbine speed signal in real time;

[0007] The steam turbine rated speed signal module is used to set and output the steam turbine rated speed signal;

[0008] A speed deviation calculation module, wherein the input end of the speed deviation calculation module is respectively connected to the steam turbine speed signal module and the steam turbine rated speed signal module; the speed deviation calculation module receives the steam turbine speed signal and the steam turbine rated speed signal, and calculates a speed deviation signal;

[0009] A first comparison module, wherein the input end of the first comparison module is respectively connected to the output end of the rotation speed deviation calculation module and the first analog signal output end; the first comparison module calculates a positive deviation signal and a negative deviation signal according to the rotation speed deviation signal and the first analog signal;

[0010] A linear rounding function module, wherein the input end of the linear rounding function module is connected to the output end of the first comparison module and the primary frequency modulation dead zone module; the linear rounding function module receives a positive deviation signal or a negative deviation signal, and calculates a positive deviation frequency modulation signal and a negative deviation frequency modulation signal;

[0011] A theoretical frequency modulation load calculation module, wherein the input end of the theoretical frequency modulation load calculation module is connected to the linear rounding function module, and after receiving the positive deviation frequency modulation signal and the negative deviation frequency modulation signal, the module calculates the theoretical frequency modulation load after processing;

[0012] A turbine valve regulating PID control module, wherein the input end of the turbine valve regulating PID control module is connected to a unit load signal module and a final load instruction module having a theoretical frequency modulation load input; the turbine valve regulating PID control module receives the unit load signal and the final load instruction, calculates and outputs a turbine valve regulating control instruction;

[0013] A circulating water pump frequency PID control module, wherein the input end of the circulating water pump frequency PID control module is connected to the unit standby pressure setting correction module and the unit back pressure actual module; the circulating water pump frequency PID control module receives the unit standby pressure setting value signal and the unit back pressure actual signal after correction, calculates and outputs the circulating water pump frequency control instruction.

[0014] Furthermore, the system further comprises:

[0015] A steam turbine valve regulating interface module, wherein the input end of the steam turbine valve regulating interface module is connected to the output end of the steam turbine valve regulating PID control module, receives the steam turbine valve regulating control instruction (15), and adjusts the opening of the steam turbine valve regulating;

[0016] A frequency converter interface module, wherein the input end of the frequency converter interface module is connected to the output end of the circulating water pump frequency PID control module, receives the circulating water pump frequency control instruction (23), and adjusts the operating frequency of the circulating water pump.

[0017] Furthermore, the linear rounding function module includes a positive linear rounding function module and a negative linear rounding function module; the positive linear rounding function module receives a speed deviation signal and processes it to obtain a positive deviation signal; the negative linear rounding function module receives a speed deviation signal and processes it to obtain a negative deviation signal.

[0018] Furthermore, the theoretical frequency regulation load calculation module includes a piecewise function processing submodule; the piecewise function processing submodule processes the positive deviation part and the negative deviation part respectively to obtain a first linear function output signal corresponding to the positive deviation part and a second linear function output signal corresponding to the negative deviation part.

[0019] Furthermore, the theoretical frequency regulation load calculation module also includes an accumulation module; the accumulation module adds the first linear function output signal and the second linear function output signal.

[0020] Furthermore, the linear rounding function modules all use the following preset functions:

[0021]

[0022] Where: M is the rated load of the unit; S is the rated speed of the turbine; α is the speed inequality of the unit; x is the function input signal, that is, the slip signal after removing the dead zone; y is the function output signal, that is, the theoretical frequency modulation load signal of primary frequency modulation.

[0023] Furthermore, the input end of the final load instruction module is respectively connected to a theoretical frequency regulation load calculation module and a unit load module.

[0024] Furthermore, the unit standby pressure setting correction module includes a comparison module, a second linear rounding function module, a switching module and a third accumulation module; the input end of the comparison module is connected to the output end of the steam turbine valve detector and the first analog signal output end; the input end of the second linear rounding function module is connected to the output end of the theoretical frequency modulation load calculation module; the input end of the switching module is connected to the output end of the comparison module and the output end of the second linear rounding function module and the second analog signal output end; the input end of the third accumulation module is connected to the output end of the switching module and the output end of the unit standby pressure setting module.

[0025] A computer program product, characterized in that the program includes any one of the modules of the above-mentioned system for steam turbine frequency regulation and load control in a thermal power plant.

[0026] A computer program product, characterized in that the program includes instructions for executing the steps in any of the systems described above.

[0027] A control method for a system for frequency regulation and load control of a steam turbine in a thermal power plant, applicable to the circulating water pump and the steam turbine valve, characterized in that the method comprises the following steps:

[0028] Step 1: real-time monitoring of turbine speed;

[0029] Step 2, setting the rated speed of the steam turbine;

[0030] Step 3, calculating the speed deviation;

[0031] Step 4: Compare the deviations and calculate the positive and negative deviation signals;

[0032] Step 5: Deviation segmentation processing;

[0033] Step 6: Calculate the theoretical frequency modulation load;

[0034] Step 7, PID output steam turbine valve adjustment;

[0035] Step 8: PID outputs the circulating water pump frequency;

[0036] Step 9: Adjust the turbine valve and circulating water pump.

[0037] Compared with the prior art, the technical solution provided by the embodiments of the present invention can at least achieve the following beneficial effects:

[0038] The circulating water pump frequency conversion is used to assist the unit's primary frequency regulation. Through the coordinated action of the turbine regulating valve and the circulating water pump frequency converter, the primary frequency regulation pass rate of the unit in the high-load section is increased, thereby improving the competitiveness and benefits of the unit's related indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0040] Figure 1 It is a schematic diagram of steps 1 to 6 of a control method of a system for frequency regulation and load control of a steam turbine in a thermal power plant according to the present invention;

[0041] Figure 2 It is a schematic diagram of step 7 of a control method of a system for frequency regulation and load control of a steam turbine in a thermal power plant according to the present invention;

[0042] Figure 3 It is a schematic diagram of step 8 of a control method of a system for frequency regulation and load control of a steam turbine in a thermal power plant according to the present invention;

[0043] Figure 4 The present invention is a schematic diagram of a system for steam turbine, frequency regulation and load control in a thermal power plant.

[0044] In the figure:

[0045] Turbine speed signal: 1

[0046] Steam turbine rated speed signal: 2

[0047] Speed ​​deviation signal: 3

[0048] Positive deviation signal: 4

[0049] Primary FM dead zone signal: 5

[0050] Positive deviation FM signal: 6

[0051] Negative deviation signal: 7

[0052] Negative deviation FM signal: 8

[0053] The first linear function output signal: 9

[0054] Second linear function output signal: 10

[0055] Theoretical frequency modulation load: 11

[0056] Unit load command signal 12

[0057] Final load command: 13

[0058] Unit load signal: 14

[0059] Steam turbine valve control command: 15

[0060] Steam turbine valve opening signal: 16

[0061] Unit standby pressure setting value 17

[0062] Piecewise function output signal: 18

[0063] Comparison result signal 19

[0064] Switching module output signal 20

[0065] The unit standby pressure set value signal after correction: 21

[0066] Actual signal of unit back pressure: 22

[0067] Circulating water pump frequency control command: 23

[0068] First analog signal: 01

[0069] Second analog signal: 02 DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] Unless otherwise defined, the technical or scientific terms used herein shall have the common meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "a" do not indicate a quantity limitation, but indicate the existence of at least one.

[0072] refer to Figures 1 to 3 The present invention provides a system for frequency regulation and load control of a steam turbine in a thermal power plant, wherein a circulating water pump is provided on the steam turbine, wherein the system comprises:

[0073] The steam turbine speed signal module is used to detect the steam turbine speed signal 1 in real time;

[0074] A steam turbine rated speed signal module is used to set and output a steam turbine rated speed signal 2;

[0075] The speed deviation calculation module, the input end of which is respectively connected to the steam turbine speed signal module and the steam turbine rated speed signal module; the steam turbine speed signal 1 and the steam turbine rated speed signal 2 are received, and the speed deviation signal 3 is calculated;

[0076] The first comparison module, the input end of the first comparison module is respectively connected to the output end of the speed deviation calculation module and the first analog signal output end, the output of the first analog signal output end is 0, the first comparison module calculates the positive deviation signal 4 and the negative deviation signal 7 according to the speed deviation signal 3 and the first analog signal 01; specifically, the first comparison module includes a large value module and a small value module, taking the large value module as an example, when the speed deviation signal 3 is negative, the positive deviation signal 4 outputs 0, and when the speed deviation signal 3 is positive, the positive deviation signal 4 outputs a numerical value, namely the speed deviation signal 3, so that the numerical value of the positive deviation signal 4 is always greater than or equal to 0; similarly, taking the small value module as an example, the numerical value of the negative deviation signal 7 is always less than 0.

[0077] A linear rounding function module, wherein the input end of the linear rounding function module is connected to the output end of the first comparison module and the primary frequency modulation dead zone module; the linear rounding function module receives the positive deviation signal 4 or the negative deviation signal 7, and calculates the positive deviation frequency modulation signal 6 and the negative deviation frequency modulation signal 8;

[0078] Theoretical frequency modulation load calculation module, the input end of the theoretical frequency modulation load calculation module is connected to the linear rounding function module, and after receiving the positive deviation frequency modulation signal 6 and the negative deviation frequency modulation signal 8, the theoretical frequency modulation load 11 is calculated after processing;

[0079] The turbine valve regulating PID (PID stands for Proportional, Integral and Derivative) control module, the input end of the turbine valve regulating PID control module is connected to the unit load signal module and the final load instruction module; the turbine valve regulating PID control module receives the unit load signal 14 and the final load instruction 13, calculates and outputs the turbine valve regulating control instruction 15;

[0080] The circulating water pump frequency PID control module, the input end of the circulating water pump frequency PID control module is connected to the unit standby pressure setting correction module and the unit back pressure actual module; the circulating water pump frequency PID control module receives the corrected unit standby pressure setting value signal 21 and the unit back pressure actual signal 22, calculates and outputs the circulating water pump frequency control instruction 23.

[0081] The present invention optimizes the operating efficiency and stability of the thermal power unit by real-time monitoring and controlling the speed of the steam turbine and the frequency of the circulating water pump. Through the PID control algorithm, the system can automatically adjust the throttle of the steam turbine and the frequency of the circulating water pump to respond to changes in the load of the power grid, thereby achieving more accurate frequency regulation and load control. In addition, by setting a frequency regulation dead zone, the situation of frequent adjustment of the control signal due to small deviations can be reduced, thereby improving the stability and response efficiency of the system.

[0082] In a preferred embodiment, a system for turbine frequency regulation and load control in a thermal power plant also includes: the input end of the steam turbine valve regulating interface module is connected to the output end of the steam turbine valve regulating PID control module, and receives the steam turbine valve regulating control instruction 15; the steam turbine valve regulating interface module can adjust the steam turbine valve regulating opening according to the steam turbine valve regulating control instruction 15.

[0083] The input end of the frequency converter interface module is connected to the output end of the circulating water pump frequency PID control module to receive the circulating water pump frequency control instruction 23 ; the frequency converter interface module can adjust the operating frequency of the circulating water pump according to the circulating water pump frequency control instruction 23 .

[0084] In a preferred embodiment, the linear rounding function module includes a positive linear rounding function module and a negative linear rounding function module; the positive linear rounding function module receives a positive deviation signal 4 and a positive primary frequency modulation dead zone signal 5, and adds the two together to obtain a positive deviation frequency modulation signal 6; the negative linear rounding function module receives a negative deviation signal 7 and a negative primary frequency modulation dead zone signal 5, and adds the two together to obtain a negative deviation frequency modulation signal 8.

[0085] In a preferred embodiment, the theoretical frequency modulation load calculation module includes a piecewise function processing submodule; the piecewise function processing submodule processes the positive deviation frequency modulation signal 6 and the negative deviation frequency modulation signal 8 respectively, and obtains a first linear function output signal 9 corresponding to the positive deviation frequency modulation signal 6 and a second linear function output signal 10 corresponding to the negative deviation frequency modulation signal 8 respectively.

[0086] In a preferred embodiment, the theoretical frequency modulation load calculation module also includes a second accumulation module; the accumulation module adds the first linear function output signal 9 and the second linear function output signal 10 to obtain the theoretical frequency modulation load 11.

[0087] In a preferred embodiment, the linear rounding function modules all use the following preset functions:

[0088]

[0089] In the formula: M is the rated load of the unit; S is the rated speed of the turbine; α is the speed inequality of the unit; x is the function input signal, that is, the positive deviation frequency modulation signal 6 or the negative deviation frequency modulation signal 8; y is the function output signal, that is, the first linear function output signal 9 or the second linear function output signal 10; the preset function can round the calculated y, that is, round the y value.

[0090] Taking 350MW with a speed inequality rate of 5% as an example, the preset functions of the positive linear rounding function module of the unit are shown in Table 1, and the preset functions of the negative linear rounding function module are shown in Table 2.

[0091] Table 1

[0092] x 0 1 3 6 12 y 0 -2.33 -7 -14 -28

[0093] Table 2

[0094] x -12 -6 -3 -1 0 y 28 14 7 2.33 0

[0095] In a preferred embodiment, the input end of the final load instruction module is connected to the theoretical frequency modulation load calculation module and the unit load module respectively. The final load instruction module receives the theoretical frequency modulation load signal 11 from the theoretical frequency modulation load calculation module and the unit load instruction signal 12 from the unit load module (the load instruction from the power grid or power plant dispatch), and finally generates the final load instruction 13 after accumulation.

[0096] In a preferred embodiment, the unit standby pressure setting correction module includes a second comparison module, a piecewise function processing submodule, a switching module and a third accumulation module; the input end of the second comparison module is connected to the output end of the steam turbine valve detector and the second analog signal output end; the input end of the piecewise function processing submodule is connected to the output end of the theoretical frequency modulation load calculation module; the input end of the switching module is connected to the output end of the second comparison module and the output end of the piecewise function processing submodule and the second analog signal output end. The input end of the third accumulation module is connected to the output end of the switching module and the output end of the unit standby pressure setting module.

[0097] In a preferred embodiment, the second comparison module receives the steam turbine throttle opening signal 16 and a second analog signal (the value of which is 95, indicating that the steam turbine throttle is 95°), and then outputs a comparison result signal 19, that is, if the steam turbine throttle opening signal 16 is greater than 95, it is output, otherwise, it is output 95.

[0098] In a preferred embodiment, the input end of the piecewise function processing submodule of the unit standby pressure setting correction module is connected to the output end of the theoretical frequency modulation load calculation module; its purpose is to convert the theoretical frequency modulation load to correspond to

[0099] In a preferred embodiment, the piecewise function preset in the piecewise function processing submodule of the unit standby pressure setting correction module is:

[0100]

[0101] Taking a 350MW unit as an example, the piecewise function is shown in Table 3

[0102] Table 3

[0103] x -12 0 1 3 12 y 0 0 -0.2 -0.5 1

[0104] The piecewise function can be used to calculate the unit back pressure set value correction signal 18 from the theoretical frequency modulation load 11.

[0105] In a preferred embodiment, the third accumulation module can accumulate the unit standby pressure setting value 17 from the unit standby pressure setting module and the switching module output signal 20 to obtain the corrected unit standby pressure setting value 21.

[0106] In a preferred embodiment, the function of the switching module is to switch the output structure according to the result of the second comparison module; specifically, if the second comparison module detects that the turbine valve opening signal 16 output by the turbine valve detector is less than or equal to the second analog signal 02 at the second analog signal output end (the signal value is 95, that is, the turbine valve opening signal), the switching module uses the first analog signal 01 as the output quantity to obtain signal 20; conversely, if the second comparison module detects that the turbine valve opening signal 16 output by the turbine valve detector is greater than the second analog signal, the switching module uses the piecewise function output signal 18 at the output end of the piecewise function processing submodule as the output quantity to obtain signal 20.

[0107] In addition to being solved by using analog circuits and digital circuits, the above modules in the present invention can also perform the above logic processing through a set computer program product.

[0108] A control method for a system for frequency regulation and load control of a steam turbine in a thermal power plant, applicable to the circulating water pump and the steam turbine valve, the method comprising the following steps:

[0109] Step 1: Real-time monitoring of turbine speed: Use the turbine speed signal module to detect the real-time speed signal 1 of the turbine.

[0110] Step 2, setting the rated speed of the steam turbine: using the rated speed signal module of the steam turbine to set and output the rated speed signal 2 of the steam turbine.

[0111] Step 3, calculating the speed deviation: the speed deviation calculation module receives the real-time speed signal 1 and the rated speed signal 2, and calculates the speed deviation signal 3.

[0112] Step 4, compare deviations and calculate positive and negative deviation signals: the first comparison module compares the rotation speed deviation signal 3 with the preset zero value signal 01 to generate a positive deviation signal 4 and a negative deviation signal 7 respectively.

[0113] Step 5, deviation segment processing: the linear rounding function module receives the positive deviation signal 4 and the negative deviation signal 7, and calculates the positive deviation frequency modulation signal 6 and the negative deviation frequency modulation signal 8.

[0114] Step 6, calculating the theoretical frequency modulation load: the theoretical frequency modulation load calculation module receives the positive deviation frequency modulation signal 6 and the negative deviation frequency modulation signal 8, and calculates the theoretical frequency modulation load 11.

[0115] Step 7, PID outputs turbine valve regulation: The turbine valve regulation PID control module receives the unit load signal 14 and the final load instruction 13, calculates and outputs the turbine valve regulation control instruction 15 through the PID control algorithm.

[0116] Step 8, PID output circulating water pump frequency: The circulating water pump frequency PID control module receives the corrected unit standby pressure set value signal 21 and the unit back pressure actual signal 22, calculates and outputs the circulating water pump frequency control instruction 23.

[0117] Step 9, turbine valve adjustment and circulating water pump adjustment: the turbine valve adjustment interface module adjusts the turbine valve opening according to the turbine valve adjustment control instruction 15. The frequency converter interface module adjusts the operating frequency of the circulating water pump according to the circulating water pump frequency control instruction 23.

[0118] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the protection scope of the present invention. The protection scope of the present invention is determined by the appended claims.

Claims

1. A system for frequency regulation and load control of a steam turbine in a thermal power plant, wherein the steam turbine is provided with a variable frequency circulating water pump, characterized in that: The system comprises: A steam turbine speed signal module, used for real-time detection of a steam turbine speed signal (1); A steam turbine rated speed signal module, used for setting and outputting a steam turbine rated speed signal (2); A speed deviation calculation module, wherein the input end of the speed deviation calculation module is respectively connected to the steam turbine speed signal module and the steam turbine rated speed signal module; the steam turbine speed signal (1) and the steam turbine rated speed signal (2) are received, and a speed deviation signal (3) is calculated; A first comparison module, wherein the input end of the first comparison module is respectively connected to the output end of the rotation speed deviation calculation module and the first analog signal output end; the first comparison module calculates a positive deviation signal (4) and a negative deviation signal (7) according to the rotation speed deviation signal (3) and the first analog signal (01); A linear rounding function module, wherein the input end of the linear rounding function module is connected to the output end of the first comparison module and the primary frequency modulation dead zone module; the linear rounding function module receives a positive deviation signal (4) or a negative deviation signal (7), and calculates a positive deviation frequency modulation signal (6) and a negative deviation frequency modulation signal (8); A theoretical frequency modulation load calculation module, wherein the input end of the theoretical frequency modulation load calculation module is connected to the linear rounding function module, and after receiving the positive deviation frequency modulation signal (6) and the negative deviation frequency modulation signal (8), the module processes and calculates the theoretical frequency modulation load (11); A turbine valve regulating PID control module, wherein the input end of the turbine valve regulating PID control module is connected to a unit load signal module and a final load instruction module having a theoretical frequency modulation load (11) as input; the turbine valve regulating PID control module receives the unit load signal (14) and the final load instruction (13), calculates and outputs a turbine valve regulating control instruction (15); A circulating water pump frequency PID control module, wherein the input end of the circulating water pump frequency PID control module is connected to a unit standby pressure setting correction module and a unit back pressure actual module; the circulating water pump frequency PID control module receives the corrected unit standby pressure setting value signal (21) and the unit back pressure actual signal (22), calculates and outputs a circulating water pump frequency control instruction (23).

2. A system for frequency regulation and load control of a steam turbine in a thermal power plant according to claim 1, characterized in that: The system further comprises: A steam turbine valve regulating interface module, wherein the input end of the steam turbine valve regulating interface module is connected to the output end of the steam turbine valve regulating PID control module, receives the steam turbine valve regulating control instruction (15), and adjusts the opening of the steam turbine valve regulating; A frequency converter interface module, wherein the input end of the frequency converter interface module is connected to the output end of the circulating water pump frequency PID control module, receives the circulating water pump frequency control instruction (23), and adjusts the operating frequency of the circulating water pump.

3. A system for frequency regulation and load control of a steam turbine in a thermal power plant according to claim 1, characterized in that: The linear rounding function module comprises a positive linear rounding function module and a negative linear rounding function module; the positive linear rounding function module receives a rotation speed deviation signal (3) and processes it to obtain a positive deviation signal (4); the negative linear rounding function module receives a rotation speed deviation signal (3) and processes it to obtain a negative deviation signal (7).

4. A system for frequency regulation and load control of a steam turbine in a thermal power plant as claimed in claim 3, characterized in that: The theoretical frequency regulation load calculation module includes a piecewise function processing submodule; the piecewise function processing submodule processes the positive deviation part and the negative deviation part respectively to obtain a first linear function output signal corresponding to the positive deviation part and a second linear function output signal corresponding to the negative deviation part.

5. A system for frequency regulation and load control of a steam turbine in a thermal power plant as claimed in claim 4, characterized in that: The theoretical frequency regulation load calculation module also includes an accumulation module; the accumulation module adds the first linear function output signal and the second linear function output signal.

6. A system for frequency regulation and load control of a steam turbine in a thermal power plant according to claim 4, characterized in that: The linear rounding function modules all use the following preset functions: Where: M is the rated load of the unit; S is the rated speed of the turbine; α is the speed inequality of the unit; x is the function input signal, that is, the slip signal after removing the dead zone; y is the function output signal, that is, the theoretical frequency modulation load signal of primary frequency modulation.

7. A system for frequency regulation and load control of a steam turbine in a thermal power plant according to claim 1, characterized in that: The input end of the final load instruction module is respectively connected to the theoretical frequency regulation load calculation module and the unit load module.

8. A system for frequency regulation and load control of a steam turbine in a thermal power plant as claimed in claim 1, characterized in that: The unit standby pressure setting correction module includes a comparison module, a second linear rounding function module, a switching module and a third accumulation module; the input end of the comparison module is connected to the output end of the steam turbine valve regulating detector and the first analog signal output end; the input end of the second linear rounding function module is connected to the output end of the theoretical frequency modulation load calculation module; the input end of the switching module is connected to the output end of the comparison module and the output end of the second linear rounding function module and the second analog signal output end; the input end of the third accumulation module is connected to the output end of the switching module and the output end of the unit standby pressure setting module.

9. A computer program product, characterized in that The program includes the modules of the system for frequency regulation and load control of steam turbines in thermal power plants according to any one of claims 1 to 8.

10. A control method for a system of steam turbine frequency modulation and load control in a thermal power plant, applicable to the circulating water pump and the steam turbine frequency modulation valve, characterized in that: The method comprises the following steps: Step 1: Real-time monitoring of the steam turbine speed: Use a steam turbine speed signal module to detect the steam turbine speed signal of the steam turbine (1). Step 2: Setting the rated speed of the steam turbine: Using the rated speed signal module of the steam turbine, the rated speed signal of the steam turbine is set and output (2). Step 3, calculating the speed deviation: The speed deviation calculation module receives the turbine speed signal (1) and the rated speed signal (2), and calculates the speed deviation signal (3). Step 4, compare deviations and calculate positive and negative deviation signals: The first comparison module compares the rotation speed deviation signal (3) with a preset zero value signal (01) to generate a positive deviation signal (4) and a negative deviation signal (7) respectively. Step 5, deviation segment processing: The linear rounding function module receives the positive deviation signal (4) and the negative deviation signal (7), and calculates the positive deviation frequency modulation signal (6) and the negative deviation frequency modulation signal (8). Step 6, calculating the theoretical frequency modulation load: The theoretical frequency modulation load calculation module receives the positive deviation frequency modulation signal (6) and the negative deviation frequency modulation signal (8), and calculates the theoretical frequency modulation load (11). Step 7, PID output of turbine valve adjustment: The turbine valve adjustment PID control module receives the unit load signal (14) and the final load command (13), calculates and outputs the turbine valve adjustment control command (15) through the PID control algorithm. Step 8, PID output of circulating water pump frequency: The circulating water pump frequency PID control module receives the corrected unit standby pressure set value signal (21) and the unit back pressure actual signal (22), calculates and outputs the circulating water pump frequency control instruction (23). Step 9, turbine valve adjustment and circulating water pump adjustment: The turbine valve adjustment interface module adjusts the turbine valve opening according to the turbine valve adjustment control instruction (15). The frequency converter interface module adjusts the operating frequency of the circulating water pump according to the circulating water pump frequency control instruction (23).

Images