A control method and system for reducing the ineffective operation of primary frequency regulation of thermal power units

Abstract

The present invention discloses a control method and system for reducing the ineffective operation of primary frequency regulation of thermal power units. The control method includes: determining a delay point according to the accuracy error of primary frequency regulation, the frequency measurement value, and the unit frequency regulation data; adjusting the open-loop circuit of the frequency modulation valve position command of the DEH (Digital Electro-Hydraulic) system through historical big data analysis; when the frequency deviation exceeds the dead zone, the CCS (Coordination Control System) power regulator outputs a prohibition of increase and decrease, and the open-loop circuit of the frequency modulation valve position of the DEH system generates a weak response; filtering through delay and judging the frequency modulation direction to eliminate the frequency modulation actions with the duration of the frequency deviation reaching the dead zone less than the delay point; supplementing the response amplitude with the duration of the frequency deviation reaching the dead zone greater than the delay point. The present invention also includes a system for executing the above method, which is applied to digital circuits and computers.

Description

Technical Field:

[0001] This application belongs to the primary frequency modulation control technology of coal-fired thermal power units, and particularly relates to a control method and system for reducing the ineffective actions of primary frequency modulation of thermal power units. Background Art:

[0002] In the case where a thermal power unit suddenly goes off the grid or the demand suddenly increases, the system will instantaneously draw energy from the rotational potential energy of the synchronous generator set, which causes the rotational speed of the generator set's shaft to slow down, and thus the grid system frequency drops accordingly. In the case where a thermal power unit suddenly increases power generation or the demand suddenly decreases, the system will accumulate the excess energy as the rotational potential energy of the conventional unit, which leads to a sudden increase in speed and an increase in the grid system frequency. Among them, the dispatching order of the power grid is one of the reasons for the above situations.

[0003] Therefore, thermal power units require automatic control methods such as primary frequency modulation and secondary frequency modulation to control the grid system frequency and keep it stable. Among them, primary frequency modulation is to maintain the balance between power consumption and power supply in a short time, while the balance between power consumption and power supply for a relatively long time or a large range should be completed by the AGC function of the unit.

[0004] Among them, the conventional primary frequency modulation method of thermal power units is the coordinated plus steam turbine automatic control method, that is, the CCS (Coordination Control System) plus DEH (Digital Electro-Hydraulic) method. Among them, the CCS system outputs to the DEH system to ensure that the amplitude of the frequency modulation response is sufficient. The DEH system is open-loop controlled to quickly respond to the grid frequency regulation. When the grid frequency increases, the primary frequency modulation function requires the thermal power unit to quickly reduce the load through the stored heat. Conversely, the thermal power unit quickly increases the load by releasing the stored heat.

[0005] Among them, the primary frequency modulation dead zone of the thermal power unit grid refers to the frequency difference set to prevent unnecessary actions of the steam turbine throttle valve when the grid frequency difference changes within a small range. However, the setting of this dead zone is a fixed value set according to the grid rules, that is, ±0.033Hz, without considering the excessive number of frequency modulation times during the operation of the thermal power unit, resulting in an increase in ineffective regulation, thus exacerbating the loss of the high-pressure regulating valve device of the steam turbine in the thermal power unit and seriously interfering with the safety and economy of the generator in the thermal power unit.

[0006] Among them, the ineffective regulation refers to a frequency modulation action with a duration less than 15 seconds (including 15 seconds) or greater than 60 seconds. According to some rules of the primary frequency modulation of the thermal power unit grid, the duration of the grid frequency deviating from 50Hz ± 0.033 greater than 15 seconds (including 15 seconds) and less than 60 seconds (including 60 seconds) is regarded as effective regulation and participates in the grid assessment. Other situations are regarded as ineffective frequency modulation and do not participate in the grid assessment.

[0007] Specifically, the situation of primary frequency regulation in this factory is as follows:

[0008] According to the sampling statistics results of this factory, when using the existing control method for primary frequency regulation of thermal power units, the situation where the grid frequency deviates from 50 ± 0.033 Hz occurs about 8,400 times per month on average. Among them, the number of times when the duration of the grid frequency deviation from 50 ± 0.033 Hz is less than 5 seconds exceeds 4,000 times per month, and the average number of effective regulation times when the deviation is from 50 ± 0.033 Hz and the duration is 15 seconds (including 15 seconds) to 60 seconds is about 60 times per month.

[0009] Therefore, under some rules of primary frequency regulation of thermal power unit power grids, 99.2% of the primary frequency regulation of the generating unit belongs to ineffective regulation, that is, there are technical problems of aggravating the loss of the high-pressure regulating valve device of the steam turbine in the thermal power unit and seriously interfering with the safety and economy of the generator in the thermal power unit.

[0010] In addition, generating units with relatively poor performance will have insufficient contribution due to the untimely response to prevent frequency modulation actions. And in the existing primary frequency regulation of thermal power units, increasing the response amplitude again will increase the number and proportion of ineffective regulations again, resulting in further aggravation of the loss of the generating unit.

[0011] Therefore, the existing control method for primary frequency regulation of thermal power units also has technical problems that are affected by factors such as measurement interference of the frequency measurement device of the generating unit, inherent precision error, and performance of the generating unit, resulting in a continuous increase in ineffective frequency modulation. Summary of the Invention:

[0012] In order to solve the above technical problems, the present invention provides a control method for reducing ineffective actions of primary frequency regulation of thermal power units. The control method includes:

[0013] Determine the delay point according to the precision error of primary frequency regulation, the frequency measurement value, and the unit frequency regulation data;

[0014] Adjust the open-loop circuit of the DEH (Digital Electro-Hydraulic) system frequency modulation valve position command through historical big data analysis;

[0015] When the frequency deviation exceeds the dead zone, the CCS (Coordination Control System) power regulator outputs a ban on increase and decrease, and the open-loop circuit of the DEH system frequency modulation valve position generates a weak response;

[0016] Eliminate the frequency modulation actions where the duration of the frequency deviation reaching the dead zone is less than the delay point through delay filtering and frequency modulation direction judgment;

[0017] The duration during which the supplementary frequency deviation reaches the dead zone is greater than the response amplitude at the delay point.

[0018] Correspondingly, the present invention also provides a system for reducing the ineffective primary frequency regulation actions of a thermal power unit, which is applied to integrated circuits and logic circuits such as controllers and arithmetic units. The system includes:

[0019] A delay unit for determining the duration during which the frequency deviation reaches the dead zone;

[0020] A frequency modulation direction judgment unit for eliminating the frequency modulation actions in which the duration during which the frequency deviation reaches the dead zone is less than the delay point through delay filtering and frequency modulation direction judgment;

[0021] A compensation unit for strengthening the given increase or decrease of the load command when the duration during which the frequency deviation reaches the dead zone is greater than the delay point;

[0022] A frequency modulation unit for performing DEH control and CCS control with compensation and prevention of reverse locking according to the given load command.

[0023] Through the above process, the control method of the present application is implemented. Without being affected by the generator set frequency measurement device and the performance of the generator set, the number of ineffective primary frequency regulations is reduced, the frequency modulation qualification rate is increased, the grid assessment index is completed, the loss of the high-pressure regulating valve device of the steam turbine in the thermal power unit caused by the ineffective actions of the unit is reduced, and the safety and economy of the generator are enhanced. Description of the Drawings:

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0025] Figure 1 Shows the primary frequency regulation action flow chart of the present invention;

[0026] Figure 2 Shows the primary frequency regulation action structure diagram of the present invention;

[0027] Figure 3 Shows the primary frequency regulation action principle diagram of the present invention;

[0028] Figure 4 Shows the primary frequency regulation action delay judgment structure diagram of the present invention;

[0029] Figure 5 Shows the primary frequency regulation action delay judgment principle diagram of the present invention;

[0030] Figure 6Shows the truth table of the logic circuit where the frequency deviation of the present invention is higher than the dead zone;

[0031] Figure 7 Shows the truth table of the logic circuit where the frequency deviation of the present invention is lower than the dead zone;

[0032] Figure 8 Shows the statistical chart of comparison data before and after implementing the control method of the present invention for Units #1, #2, #3, #4, #5, and #6 of Huaneng Yangluo Power Plant.

[0033] Among them, 1. Power command receiving module 1, 2. Average value acquisition module, 3. Frequency modulation action judgment module, 4. Power command acquisition module, 5. Logic switching module 1, 6. Load increase judgment module 1, 7. Logic greater than judgment module 1, 8. Summation module 1, 9. Logic less than judgment module 1, 10. Summation module 2, 11. Load decrease judgment module 1, 12. Logic switching module 2, 13. Logic switching module 3, 14. Load increase judgment module 2, 15. Load decrease judgment module 2, 16. Logic switching module 4, 17. Logic switching module 5, 18. Summation module 3, 19. Load command given module with frequency modulation, 20. Actual power generation acquisition module, 21. Low-frequency action prohibited load decrease instruction module, 22. High-frequency action prohibited load increase instruction module, 23. Weakened DEH system frequency modulation valve position instruction loop module, 24. Logic control module, 25. Frequency command function module, 26. Summation module 4, 27. DEH valve position given instruction output module, 28. Frequency deviation acquisition module, 29. Frequency deviation exceeding 60 seconds and invalid frequency judgment module, 30. Logic switching module 6, 31. Frequency higher than dead zone judgment module, 32. Frequency lower than dead zone judgment module, 33. Logic OR module 1, 34. Pulse delay generator module 1, 35. Logic NOT module 1, 36. Pulse delay generator module 2, 37. Logic OR module 2, 38. Logic NOT module 2, 39. Pulse delay generator module 3, 40. Pulse delay generator module 4, 41. Logic OR module 2, 42. SR flip-flop module 1, 43. SR flip-flop 2, 44. Pulse delay generator module 5, 45. Pulse delay generator module 6. Specific implementation manner:

[0034] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0035] The technical features involved in the different implementation manners of the present application described below can be combined with each other as long as they do not conflict with each other.

[0036] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0037] An embodiment of the present application provides a control method for reducing the ineffective operation of primary frequency regulation of a thermal power unit, as Figure 1 shown, including:

[0038] Determine a delay point according to the accuracy error of primary frequency regulation, the frequency measurement value, and the unit frequency regulation data;

[0039] Adjust the open-loop circuit of the frequency modulation valve position of the DEH (Digital Electro-Hydraulic) system through historical big data analysis;

[0040] When the frequency deviation exceeds the dead zone, the CCS (Coordination Control System) power regulator outputs a prohibition of increase and decrease, and the open-loop circuit of the frequency modulation valve position of the DEH system generates a weak response;

[0041] Filter out the frequency modulation actions with the duration of the frequency deviation reaching the dead zone less than the delay point through delay filtering and frequency modulation direction judgment;

[0042] Supplement the response amplitude with the duration of the frequency deviation reaching the dead zone greater than the delay point.

[0043] Among them, determining the delay point according to the accuracy error of primary frequency regulation, the frequency measurement value, and the unit frequency regulation data is specifically:

[0044] Obtain the accuracy error of the primary frequency regulation of the thermal power unit through the comparison between the grid dispatching assessment detailed list and the sampled measurement quantity of the primary frequency regulation frequency of the thermal power unit, and record the accuracy error exceeding a certain range;

[0045] Count the number of frequency modulation actions of the thermal power unit for different durations, and analyze the monthly and annual frequency modulation action times of the thermal power unit;

[0046] Adjust the delay point according to the number of frequency modulation actions and the accuracy error exceeding a certain range;

[0047] The delay point is greater than 4 seconds and less than 6 seconds.

[0048] Among them, adjusting the open-loop circuit of the frequency modulation valve position of the DEH (Digital Electro-Hydraulic) system through historical big data analysis and determining the delay point is specifically:

[0049] By analyzing historical big data, the relationship between the change in the actual power generation of a thermal power unit and the change in the required DEH valve position command is analyzed, and the frequency modulation valve position command loop of the DEH system is adjusted accordingly.

[0050] Therefore, the control method of this application can reduce the number of ineffective primary frequency modulation times without being affected by the quality of the generator set frequency measurement device and the performance of the generator set.

[0051] Among them, the delay filtering is that when the frequency deviation exceeds the dead zone, the CCS (Coordination Control System) system outputs a prohibition of increase or decrease, and the open-loop loop of the DEH system frequency modulation valve position command generates a weak response without delay. Specifically:

[0052] The load command input to the CCS system is a power command without primary frequency modulation.

[0053] When the frequency deviation is higher than the dead zone, the output to the DEH valve position command is prohibited. When the frequency deviation is lower than the dead zone, the output to the DEH valve position command is prohibited from decreasing.

[0054] The weak response of the open-loop loop of the DEH system frequency modulation valve position command is output to the DEH valve position command.

[0055] The weak response of the open-loop loop of the DEH system frequency modulation valve position command is: when the frequency deviation is higher than the dead zone, the DEH system frequency modulation valve position command loop is +0.2 MW; when the frequency deviation is lower than the dead zone, the DEH system frequency modulation valve position command loop is -0.2 MW.

[0056] The DEH valve position command is converted into a flow signal to directly control the opening of the steam turbine control valve, change the load of the thermal power unit, and enable the thermal power unit to quickly respond to the needs of primary frequency modulation.

[0057] Therefore, the control method of this application can meet the rules of the primary frequency modulation of the thermal power unit grid where the load response lag time of the primary frequency modulation is less than 3 seconds, and can also meet the situation where the grid regulation command takes precedence over the power plant regulation command and can quickly respond when a large frequency fluctuation occurs.

[0058] Among them, through delay filtering and frequency modulation direction judgment, the frequency modulation actions with the duration of the frequency deviation reaching the dead zone less than the delay point are eliminated, including:

[0059] The frequency deviation is the difference between the actual grid frequency and the grid operating frequency of 50 Hz.

[0060] The frequency modulation direction judgment is that when the duration of the frequency deviation exceeding the dead zone is greater than the filtering point and less than the delay point, the CCS system load given command is consistent with the frequency modulation direction.

[0061] The filtering point is greater than 2 seconds and less than 4 seconds.

[0062] When the frequency deviation is lower than the dead zone and its duration is less than the delay point, the maximum value of the power command and the actual power plus the frequency modulation command is the load command given to the input CCS system.

[0063] When the frequency deviation is higher than the dead zone and its duration is less than the delay point, the minimum value of the power command and the actual power minus the frequency modulation command is the load command given to the input CCS system.

[0064] Therefore, the control method of this application can avoid that in the actual operation of a thermal power unit, the given load command is always consistent with the frequency modulation direction, that is, the output of the power regulation PID control in the CCS system is consistent with the frequency modulation direction, effectively avoiding reverse regulation in primary frequency modulation.

[0065] Moreover, the control method of this application can also eliminate the frequency modulation actions in which the duration of the frequency deviation reaching the dead zone during the actual operation of the thermal power unit is less than 3 seconds and the actions are ineffective, making the curve of the given load command smoother and the output DEH valve position command smoother, while greatly reducing the loss of the high-pressure regulating valve device of the steam turbine in the thermal power unit caused by ineffective actions, and enhancing the safety and economy of the generator.

[0066] The reverse regulation of the primary frequency modulation is that when the frequency deviation is higher than the dead zone, the output of the DEH valve position command increases, that is, the power does not decrease but increases; when the frequency deviation is lower than the dead zone, the output of the DEH valve position command decreases, that is, the power does not increase but decreases.

[0067] Among them, by supplementing the response amplitude when the duration of the frequency deviation reaching the dead zone is greater than the delay point to meet the frequency modulation contribution and ensure the frequency stability of the power grid system, including:

[0068] When the duration of the frequency deviation higher than the dead zone is greater than the delay point, slightly reduce the load command given to the input CCS system, and the DEH system responds according to the power grid rules;

[0069] When the duration of the frequency deviation higher than the dead zone is greater than the delay point, slightly increase the load command given to the input CCS system, and the DEH system responds according to the power grid rules;

[0070] When the duration of the frequency deviation reaching the dead zone is greater than the enhancement point, the DEH system increases the response under the power grid rules;

[0071] The enhancement point is greater than or equal to 6 seconds and less than 15 seconds;

[0072] When the duration of the frequency deviation reaching the dead zone is greater than 60 seconds, stop primary frequency modulation.

[0073] Therefore, the control method of the present application can meet the grid assessment index that the unit load should reach 90% of the maximum load adjustment range of the primary frequency regulation calculated theoretically within 15 seconds under the condition of reducing the ineffective operation of the primary frequency regulation.

[0074] The embodiment of the present application further provides a system for reducing the ineffective operation of the primary frequency regulation of a thermal power unit, which is applied to digital circuits such as controllers and arithmetic units and computers, and includes:

[0075] A delay unit, by determining the duration of the frequency deviation reaching the dead zone, controls the value of the load command given, and reduces the frequency modulation action whose duration of the frequency deviation reaching the dead zone is less than the delay point, as Figure 4 and Figure 5 shown. Specifically:

[0076] The frequency deviation exceeds 60 seconds and the invalid frequency judgment module 29 is connected to the logic switching module six 30 for logical judgment. When the frequency deviation exceeds 60 seconds or it is determined that the frequency is an invalid frequency, the judgment result of the logic switching module six 30 is true, and a zero signal is output to the low-frequency action prohibition reduction instruction module 21, the high-frequency action prohibition increase instruction module 22, the frequency higher than the dead zone judgment module 31, and the frequency lower than the dead zone judgment module 32. Otherwise, the frequency deviation acquisition module 28 outputs to the above modules for logical judgment.

[0077] The frequency deviation acquisition module 28 acquires the difference between the actual frequency of the power grid and the operating frequency of the power grid, which is 50 Hz.

[0078] The 60 seconds is the frequency upper limit of the effective operation of the primary frequency regulation of the thermal power unit.

[0079] When the frequency deviation is higher than the dead zone, the frequency higher than the dead zone judgment module 31 and the high-frequency action prohibition increase instruction module 22 output load commands, and the frequency lower than the dead zone judgment module 32 and the low-frequency action prohibition reduction instruction module 21 do not output load commands.

[0080] When the frequency deviation is lower than the dead zone, the frequency lower than the dead zone judgment module 32 and the low-frequency action prohibition reduction instruction module 21 output load commands, and the frequency higher than the dead zone judgment module 31 and the high-frequency action prohibition increase instruction module 22 do not output load commands.

[0081] When the frequency deviation is not higher than the dead zone and not lower than the dead zone, the frequency deviation acquisition module 28 outputs to the low-frequency action prohibition reduction instruction module 21, the high-frequency action prohibition increase instruction module 22, the frequency higher than the dead zone judgment module 31, and the frequency lower than the dead zone judgment module 32, and none of them output load commands.

[0082] The low-frequency action inhibition reduction instruction module 21 and the high-frequency action inhibition increase instruction module 22 are connected to the logical OR module 33. When the low-frequency action inhibition reduction instruction module 21 or the high-frequency action inhibition increase instruction module 22 outputs a load instruction, the logical OR module 33 outputs the load instruction to the frequency modulation action judgment result module 3 without delay, causing it to output the load instruction.

[0083] When the frequency higher than dead zone judgment module 31 outputs a load instruction and the frequency lower than dead zone judgment module 32 does not output a load instruction, the logic executed by the pulse delay generator module 34, the logical NOT module 35, the pulse delay generator module 36, the logical OR module 37, the logical NOT module 38, the pulse delay generator module 39, the pulse delay generator module 40, the logical OR module 41, the SR flip-flop 42, and the SR flip-flop 43 is as Figure 6 shown.

[0084] When the frequency lower than dead zone judgment module 32 outputs a load instruction and the frequency higher than dead zone judgment module 31 does not output a load instruction, the logic executed by the above modules is as Figure 7 shown.

[0085] When the S terminal of the SR flip-flop receives no load instruction and the R terminal receives a load instruction, it outputs a load instruction; when the R terminal of the SR flip-flop receives no load instruction and the S terminal receives a load instruction, it does not output a load instruction.

[0086] The load reduction judgment module 11 is connected to the load reduction judgment module 15 through the pulse delay generator module 44, so that the signal of the load reduction judgment module 11 is delayed by 2 seconds in the pulse delay generator module 44 and input into the load reduction judgment module 15.

[0087] The load increase judgment module 6 is connected to the load increase judgment module 14 through the pulse delay generator module 45, so that the signal of the load increase judgment module 6 is delayed by 2 seconds in the pulse delay generator module 45 and input into the load increase judgment module 14.

[0088] The pulse delay generator module 44 and the pulse delay generator module 45 can analyze the frequency modulation data of the unit according to big data and historical data and change the delay point. Specifically:

[0089] According to the grid dispatching assessment detailed list and the primary frequency modulation frequency sampling measurement of the thermal power unit, the accuracy error, the accuracy value, and the hysteresis value of the primary frequency modulation frequency measurement of the thermal power unit are obtained. If the accuracy error exceeds the range, correction is performed.

[0090] The thermal power unit counts the frequency regulation action times at 0 - 5 seconds, 6 - 14 seconds, 15 - 60 seconds, and greater than 60 seconds each day, and analyzes the monthly and annual frequency regulation action times of the thermal power unit every day to adjust the delay point.

[0091] The DEH valve position command range is 0 - 100, and the normal operating value is 82 ± 15. By analyzing the historical big data, when the actual power generation of the thermal power unit changes by ±0.2 MW, the change amount of the required DEH valve position command is generally about ±0.3. According to the change amount of the required DEH valve position command, the frequency regulation valve position command loop 23 of the weakened DEH system is changed.

[0092] Therefore, through the delay module, low - frequency commands and high - frequency commands with the duration of the frequency deviation exceeding the dead zone and being greater than the filtering point, and low - frequency commands and high - frequency commands with the duration being greater than the delay point can be obtained through the pulse delay generator module, SR flip - flop module, and logic judgment module. When the duration of the frequency deviation reaching the dead zone is greater than 60 seconds, the primary frequency regulation is stopped.

[0093] Therefore, the system of this application can reduce the number of ineffective primary frequency regulations through historical big data analysis without being affected by the quality of the generator set frequency measurement device and the performance of the generator set.

[0094] The logic judgment module includes a logical NOT module and a logical OR module.

[0095] The frequency regulation direction judgment unit eliminates the frequency regulation actions with the duration of the frequency deviation reaching the dead zone being less than the delay point through delay filtering and frequency regulation direction judgment, as Figure 2 and Figure 3 shown. Specifically:

[0096] The frequency regulation action judgment module 3 obtains the frequency regulation action judgment result without delay and is connected in series with the logic switching module 1 - 5. When the frequency regulation action judgment result is a true signal, the current load command output is maintained through locking; when the frequency regulation action judgment result is a false signal, the average actual power generation of the generator of the thermal power unit in the current 5 seconds is collected through the average value acquisition module 2, that is, the actual power output from the thermal power unit to the power grid, and is output.

[0097] The logic switching module 1 - 5 and the power command receiving module 1 - 1 are input into the logic greater - than judgment module 1 - 7 for size comparison, and the larger load command is output to the summation module 1 - 8.

[0098] The logic switching module 1 - 5 and the power command receiving module 1 - 1 are input into the logic less - than judgment module 1 - 9 for size comparison, and the smaller load command is output to the summation module 2 - 10.

[0099] The power command receiving module 1 receives the power command without primary frequency regulation. The power command acquisition module 4 is respectively connected to the summing module 1 8 and the summing module 2 10. The summing module 1 8 and the summing module 2 10 respectively sum the input load commands, and send the summing results to the logic switching module 2 12 and the logic switching module 3 13 for logical judgment.

[0100] The power command acquisition module 4 receives the actual frequency regulation power command, that is, the actual operating power of the primary frequency regulation thermal power unit.

[0101] Therefore, the system of the present application can obtain the maximum value of the power command and the actual generated power, as well as the minimum value of the power command and the actual generated power, that is, according to the load of the thermal power unit, primary frequency regulation is performed to make the system of the present application meet the requirements of the maximum and minimum frequency regulation load increase and decrease ranges specified by primary frequency regulation.

[0102] When the low-frequency exceeds the filter point and the load command is input to the load increase judgment module 1 6, the logic switching module 2 12 judges that the result is true and outputs the summing result of the summing module 1 8. Otherwise, the logic switching module 2 12 judges that the result is false and outputs the load command of the power command receiving module 1.

[0103] The load increase judgment module 1 6 receives the load increase judgment result of the delay unit.

[0104] When the high-frequency exceeds the filter point and the load command is input to the load decrease judgment module 1 11, the logic switching module 3 13 judges that the result is true and outputs the summing result of the summing module 2 10. Otherwise, the logic switching module 3 13 judges that the result is false and outputs the load command of the power command receiving module 1.

[0105] The load decrease judgment module 1 11 receives the load decrease judgment result of the delay unit.

[0106] The load command passes through the summing module 3 18 to the load command given module 19 with frequency regulation and is input to the CCS system of the logic control module 24.

[0107] Therefore, the frequency regulation direction judgment unit can make the load command input to the CCS system be the power command without primary frequency regulation when the duration of the delay module is greater than the low-frequency command and the high-frequency command of the filter point, and the duration of the frequency deviation exceeding the dead zone is less than the filter point.

[0108] Therefore, the FM direction determination unit can, according to the low-frequency instruction that the duration of the delay module is greater than the filtering point, input the load instruction given as the maximum value of the power instruction and the actual power plus the FM instruction; according to the high-frequency instruction that the duration of the delay module is greater than the filtering point, input the load instruction given as the minimum value of the power instruction and the actual power minus the FM instruction, to prevent the reverse regulation of the relatively small frequency deviation that cannot be promptly reflected by the PID control.

[0109] Therefore, in the FM direction determination unit, the result of the delay module can eliminate the FM actions with the duration of the frequency deviation reaching the dead zone being less than the delay point.

[0110] Therefore, the system of the present application can avoid the state where the steam turbine speed curve frequently fluctuates up and down and is sometimes high and sometimes low during the actual operation of the thermal power unit, resulting in corresponding fluctuations in the given load instruction, affecting the integral variable of the PID control in the CCS system, and causing reverse regulation in primary frequency modulation.

[0111] Moreover, the system of the present application can also eliminate the FM actions with the duration of the frequency deviation reaching the dead zone being less than 3 seconds and generating ineffective actions during the actual operation of the thermal power unit, making the curve of the given load instruction smoother and the output DEH valve position instruction smoother, and greatly reducing the loss of the steam turbine high-pressure regulating valve device in the thermal power unit caused by the ineffective actions of the unit, enhancing the safety and economy of the generator.

[0112] The compensation unit strengthens the increase and decrease of the given load instruction when the duration of the frequency deviation reaching the dead zone is greater than the delay point, specifically:

[0113] The load increase judgment module two 14 is connected to the logic switching module four 16 for logical judgment. When the result of the load increase judgment module two 14 is true, the variable A1 is output to the summation module three 18.

[0114] The load decrease judgment module two 15 is connected to the logic switching module five 17 for logical judgment. When the result of the load decrease judgment module two 15 is true, the variable A2 is output to the summation module three 18.

[0115] In this embodiment, the values of the variable A1 and the variable A2 are set to 0.4 MW and -0.4 MW respectively.

[0116] Therefore, through the compensation unit, for the low-frequency instruction with a duration greater than the delay point, the given load instruction input to the CCS system is increased; for the high-frequency instruction with a duration greater than the delay point, the given load instruction input to the CCS system is decreased.

[0117] Therefore, the compensation unit can increase the FM response amplitude.

[0118] Therefore, the system of the present application can meet the grid assessment index that the unit load should reach 90% of the maximum load adjustment range of the primary frequency modulation calculated theoretically within 15 seconds under the condition of reducing the ineffective operation of the primary frequency modulation.

[0119] The frequency modulation unit performs DEH control and CCS control with compensation and reverse lockout prevention according to the given load command, specifically:

[0120] The summation module three 18 outputs to the load command given module 19 with frequency modulation, and the load command given module 19 with frequency modulation outputs the given load command to the logic control module 24.

[0121] The logic control module 24 includes a DEH control system and a CCS power PID control system.

[0122] The logic control module 24 performs time-division PID control according to the input signals of the load command given module 19 with frequency modulation, the actual power generation acquisition module 20, the low-frequency operation prohibition reduction command module 21, and the high-frequency operation prohibition increase command module 22, specifically:

[0123] After the frequency deviation exceeds the dead zone and is greater than 5 seconds, the CCS system accelerates the response.

[0124] After the duration of the frequency deviation exceeding the dead zone is greater than 5 seconds, the DEH system starts to respond according to the grid rules.

[0125] After the duration of the frequency deviation exceeding the dead zone is greater than or equal to 6 seconds, the DEH system increases the response amplitude according to the grid rules.

[0126] According to the inputs of the low-frequency operation prohibition reduction command module 21 and the high-frequency operation prohibition increase command module 22, the output load command of the logic control module 24 is controlled to prevent reverse lockout, that is, when the frequency deviation is higher than the dead zone, increasing the output load command is prohibited, and when the frequency deviation is lower than the dead zone, reducing the load command is prohibited.

[0127] The PID control may include:

[0128] Through the logical judgment as Figure 1 shown, the CCS and DEH respond in time-division:

[0129] After the frequency deviation exceeds the dead zone and is greater than 5 seconds, the CCS regulation system accelerates the response.

[0130] When the frequency deviation exceeds the dead zone, the DEH regulation system has a weak unconditional response.

[0131] After the frequency deviation exceeds the dead zone and is greater than 5 seconds, it starts to respond according to the grid rules.

[0132] After the frequency deviation exceeds the dead zone and is greater than or equal to 6 seconds, the response amplitude is increased according to the grid rules.

[0133] The said DEH system is an open-loop control, and CCS is a closed-loop control.

[0134] The DEH valve position command output by the DEH system directly controls the steam turbine governing valve, which is used to change the load of the unit, so that the unit can quickly respond to the needs of primary frequency modulation.

[0135] The said CCS system finally stabilizes the load of primary frequency modulation. The CCS (Coordination Control System) system performs PID control and outputs it to the DEH system. The DEH system performs PID control and outputs the said DEH valve position command to the thermal power unit to control the actual frequency of the power grid.

[0136] The said CCS system can improve the accuracy and stability of the unit's primary frequency modulation.

[0137] Therefore, without being affected by the generator frequency measurement device and the performance of the generator set, the number of ineffective primary frequency modulation times is reduced, the qualified rate of frequency modulation is increased, the grid assessment index is completed, the loss of the steam turbine high-pressure regulating valve device in the thermal power unit caused by the ineffective actions of the unit is reduced, and the safety and economy of the generator are enhanced. The beneficial effects are as Figure 8 shown.

[0138] The control method of this application can also be improved through debugging on this basis to make it conform to the state of the thermal power unit. Specifically:

[0139] Use a signal generator to simulate the frequency deviation signal, and detect the frequency deviation exceeding 60 seconds, the ineffective frequency judgment, the frequency modulation action logic, and the frequency modulation delay logic.

[0140] Use a signal generator to simulate a small frequency 50Hz±0.004Hz signal, and detect whether the load setting is consistent with the frequency modulation direction, that is, when the frequency is lower than 49.977, the load setting is greater than or equal to the actual power generation; when the frequency is higher than 50.033, the load setting is less than or equal to the actual power generation. Ensure that the PID steam turbine main control module does not reverse adjust.

[0141] Use a signal generator to simulate a small frequency 50Hz±0.004Hz signal, and keep this frequency for 15 seconds, 25 seconds, 35 seconds, and 45 seconds respectively. Check that the frequency modulation contribution is not less than 120% of the grid rule. If it does not meet the requirement, adjust Figure 3 the A1 and A2 values in it.

[0142] For the grid frequency modulation rule, the unit load response is not greater than the filtering point. Use a signal generator to simulate a small frequency 50Hz±0.004 signal, and by adjusting the value of the weakened DEH system frequency modulation valve position command loop function, ensure that the power response change value is not greater than ±0.2MW.

[0143] Therefore, the control method of this embodiment can reduce the influence of the generator set frequency measurement device and the performance of the generator set, reduce the number of ineffective primary frequency regulations, increase the qualified rate of frequency regulation, meet the grid assessment indicators, reduce the loss of the steam turbine high-pressure regulating valve device in the thermal power unit caused by ineffective actions of the unit, and enhance the safety and economy of the generator.

[0144] Therefore, this application can reduce the number of ineffective primary frequency regulations, increase the qualified rate of frequency regulation, meet the grid assessment indicators, reduce the loss of the steam turbine high-pressure regulating valve device in the thermal power unit caused by ineffective actions of the unit, and enhance the safety and economy of the generator.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of this application.

Claims

1. A control method for reducing the ineffective operation of primary frequency regulation of thermal power units, characterized in that, Including: Determine the delay point according to the precision error of primary frequency regulation, the measured frequency value, and the unit frequency regulation data; Adjust the open-loop circuit of the frequency modulation valve position command of the DEH (Digital Electro-Hydraulic) system through historical big data analysis; When the frequency deviation exceeds the dead zone, the CCS (Coordination Control System) power regulator outputs a prohibition on increasing and decreasing, and the open-loop circuit of the frequency modulation valve position of the DEH system generates a weak response; Eliminate the frequency modulation actions with a duration of the frequency deviation reaching the dead zone less than the delay point through delay filtering and frequency modulation direction judgment; Supplement the response amplitude with a duration of the frequency deviation reaching the dead zone greater than the delay point; Determine the delay point and adjust the open-loop circuit of the frequency modulation valve position command of the DEH system, including: Obtain the precision error of the primary frequency regulation of the thermal power unit through the comparison between the grid dispatching assessment detail list and the sampled measurement of the primary frequency regulation frequency of the thermal power unit, and record the precision error exceeding a certain range; Count the number of frequency modulation actions of the thermal power unit for different durations, and analyze the monthly and annual frequency modulation action times of the thermal power unit; Adjust the delay point according to the number of frequency modulation actions and the precision error exceeding a certain range; The delay point is greater than 4 seconds and less than 6 seconds; Through historical big data analysis, analyze the relationship between the change in the actual power generation of the thermal power unit and the change in the required DEH valve position command, and adjust the frequency modulation valve position command circuit of the DEH system accordingly; Among them, the CCS power regulator outputs a prohibition on increasing and decreasing, and the open-loop circuit of the frequency modulation valve position of the DEH system generates a weak response, including: The load command input to the CCS power regulator is a power command without primary frequency regulation; When the frequency deviation is higher than the dead zone, prohibit increasing the output to the DEH valve position command, and when the frequency deviation is lower than the dead zone, prohibit decreasing the output to the DEH valve position command; The weak response generated by the frequency modulation valve position command circuit of the DEH system is not more than ±0.5MW; Eliminate the frequency modulation actions with a duration of the frequency deviation reaching the dead zone less than the delay point, including: The frequency deviation is the difference between the actual grid frequency and the grid operating frequency of 50Hz; When the duration of the frequency deviation exceeding the dead zone is greater than the filtering point and less than the delay point, make the load given command of the CCS system consistent with the frequency modulation direction; The filtering point is greater than 2 seconds and less than 4 seconds.

2. The control method according to claim 1, wherein, The load given command of the CCS system is consistent with the frequency modulation direction, including: When the duration of the frequency deviation lower than the dead zone is greater than the filtering point and less than the delay point, the maximum value of the power command and the actual power generation is the load command input to the CCS system; When the duration of the frequency deviation higher than the dead zone is greater than the filtering point and less than the delay point, the minimum value of the power command and the actual power generation is the load command input to the CCS system.

3. The control method according to claim 1, wherein Supplement the response amplitude, including: When the duration of the frequency deviation higher than the dead zone is greater than the delay point, slightly reduce the load command input to the CCS system, and the DEH system responds according to the grid rules; When the duration of the frequency deviation lower than the dead zone is greater than the delay point, slightly increase the load command input to the CCS system, and the DEH system responds according to the grid rules; When the duration of the frequency deviation reaching the dead zone is greater than the enhancement point, the DEH system increases the response under the grid rules; The enhancement point is greater than or equal to 6 seconds and less than 15 seconds; When the duration of the frequency deviation reaching the dead zone is greater than 60 seconds, the primary frequency modulation is stopped.

4. A system for reducing the ineffective operation of primary frequency regulation of thermal power units, characterized in that, It includes: A delay unit that determines the duration of the frequency deviation reaching the dead zone; A frequency modulation direction judgment unit that filters out the frequency modulation actions with the duration of the frequency deviation reaching the dead zone less than the delay point through delay filtering and frequency modulation direction judgment; A compensation unit that strengthens the increase and decrease of the load command given when the duration of the frequency deviation reaching the dead zone is greater than the delay point; A frequency modulation unit that performs DEH control and CCS control with compensation and prohibited increase and decrease according to the given load command; The delay unit includes: Through a pulse delay generator module, an SR flip-flop module, and a logic judgment module, low-frequency instructions and high-frequency instructions with the duration of the frequency deviation exceeding the dead zone greater than the filtering point, and low-frequency instructions and high-frequency instructions with the duration greater than the delay point are obtained; When the duration of the frequency deviation reaching the dead zone is greater than 60 seconds, the primary frequency modulation is stopped; The filtering point is greater than 2 seconds and less than 4 seconds; The delay point is greater than 4 seconds and less than 6 seconds; The frequency modulation direction judgment unit includes: According to the low-frequency instructions and high-frequency instructions with the duration of the delay module greater than the filtering point, when the duration of the frequency deviation exceeding the dead zone is less than the filtering point, the load command given input to the CCS system is a power command without primary frequency modulation; According to the low-frequency instructions with the duration of the delay module greater than the filtering point, the load command given input is the maximum value of the power command and the actual power plus the frequency modulation command; According to the high-frequency instructions with the duration of the delay module greater than the filtering point, the load command given input is the minimum value of the power command and the actual power minus the frequency modulation command; The filtering point is greater than 2 seconds and less than 4 seconds.

5. The system according to claim 4, wherein The compensation unit and the frequency modulation unit include: The frequency modulation unit includes a logic switching module, a logic control module, and a DEH system frequency modulation valve position command loop; Through the compensation unit, the low-frequency instructions with the duration greater than the delay point slightly increase the load command given input to the CCS system; Through the compensation unit, the high-frequency instructions with the duration greater than the delay point slightly decrease the load command given input to the CCS system; The DEH system frequency modulation valve position command open-loop loop generates a weak response when the frequency deviation exceeds the dead zone to ensure that the unit load response is consistent with the frequency modulation direction; The logic control module includes a CCS power PID control system and a DEH system; Through the logic control module, when the duration is greater than the delay point, the DEH system responds according to the grid rules, and when the duration is greater than the enhancement point, the DEH system slightly increases the response under the grid rules; The logic control module adjusts the DEH system frequency modulation valve position command open-loop loop through historical big data analysis; The logic control module enables the CCS system to output prohibited increase or prohibited decrease when the frequency deviation exceeds the dead zone; The delay point is greater than 4 seconds and less than 6 seconds; The enhancement point is greater than or equal to 6 seconds and less than 15 seconds; The DEH system frequency modulation valve position command open-loop loop and the logic control module output to the DEH valve position command.

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