Control method for improving qualification rate of primary frequency modulation action of thermal power generating unit

Abstract

The invention belongs to the technical field of primary frequency modulation of a thermal power generating unit, and particularly relates to a control method for improving the primary frequency modulation action qualification rate of the thermal power generating unit. Comprising the following steps: S1, converting a main transformer high-voltage side frequency signal collected by a frequency transmitter into a rotating speed signal after grid connection of a unit, and when the frequency signal participating in primary frequency modulation after grid connection of the unit fails, switching back to an original primary frequency modulation loop of the unit; s2, calculating the contribution rate of the primary frequency modulation of the unit; s3, constructing a unit primary frequency modulation contribution rate compensation logic; s4, constructing valve position factor compensation logic; and S5, constructing power factor compensation logic. When the thermal power generating unit carries out primary frequency modulation action, it is guaranteed that the control valve of the unit does not act violently, and it is also guaranteed that the theoretical action amount of primary frequency modulation meets related requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of primary frequency regulation of thermal power units, and in particular relates to a control method for improving the qualified rate of primary frequency regulation actions of thermal power units. Background Art

[0002] The primary frequency regulation of thermal power units refers to the automatic control process in which the control system of the units in the power grid automatically controls the increase or decrease of the active power of the units, limits the frequency change of the power grid, and maintains a stable frequency of the power grid once the frequency of the power grid deviates from the rated value. The existing primary frequency regulation control technology calculates the power factor and valve position factor corresponding to the frequency fluctuation of the power grid through the speed inequality rate, so that the units can follow the fluctuation of the power grid frequency accordingly. Due to various factors such as the frequency signal of most units being different from the test frequency signal of the power grid, the non-linear valve position flow curve, and the unreasonable sliding pressure curve, the primary frequency regulation pass rate of the units is low.

[0003] Taking Henan Power Grid as an example, Henan Power Grid is now relatively large and highly adaptable, so that the primary frequency regulation of Henan Power Grid is mostly a small frequency difference fluctuation (around 0.06Hz). The current optimization measures are that some power plants improve the primary frequency regulation performance by modifying the primary frequency regulation network parameters, reducing the local speed inequality rate, and strengthening the primary frequency regulation feedforward. This measure may cause the primary frequency regulation to fluctuate too much when the primary frequency regulation is in action, causing unit power fluctuations, which brings great safety hazards to the power grid and the unit. The defects of the existing technology include: At present, some power plants use the unit speed as a substitute for the grid primary frequency regulation assessment frequency, which is different from the grid assessment frequency, resulting in differences between the unit primary frequency regulation action and the grid primary frequency regulation action; At present, some power plants have adopted the method of reducing the local speed inequality to improve the primary frequency regulation performance. The disadvantage is that if the grid frequency fluctuates frequently in a small range outside the dead zone (without returning to the dead zone), the unit will reduce the local speed inequality, which will cause the unit's regulating valve and corresponding oil circuit to fluctuate violently. In severe cases, the regulating valve core may break or the oil circuit may leak oil. At present, some power plants adopt the method of strengthening the primary frequency regulation feedforward to improve the primary frequency regulation performance. The disadvantage is that due to various factors such as the nonlinear valve position flow curve of the unit and the unreasonable sliding pressure curve, the strengthened primary frequency regulation feedforward is an open loop (the feedforward may be too large or too small), and no closed loop is formed, which will cause the primary frequency regulation action to be too large or too small; At present, the amount of primary frequency regulation power factor action in most power plants is loaded on the unit load instruction. If there is a deviation between the unit load and the unit instruction itself during the primary frequency regulation action, the primary frequency regulation action amount will be too large or too small.

[0004] Therefore, whether it is possible to provide a primary frequency regulation action qualification rate control method that can ensure that the unit's throttle does not act violently, ensure that the theoretical action amount of the primary frequency regulation meets the relevant requirements, and enhance the response capability of the primary frequency regulation so that the unit can respond to the frequency regulation needs of the power grid more quickly is a technical problem that the present invention urgently needs to solve. Summary of the invention

[0005] In view of this, the present invention provides a control method for improving the pass rate of primary frequency modulation action of a thermal power unit.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A control method for improving the qualified rate of primary frequency modulation action of a thermal power unit comprises the following steps: S1. Install frequency transmitters on the high-voltage sides of the three main transformers respectively, convert the frequency signals collected by the frequency transmitters into speed signals after the unit is connected to the grid, and use them to participate in the primary frequency regulation of the unit. When the speed signal participating in the primary frequency regulation fails after the unit is connected to the grid, switch back to the original primary frequency regulation circuit of the unit; S2. Construct the calculation logic of the primary frequency regulation contribution rate of the unit, and obtain the primary frequency regulation contribution rate by inputting the actual load of the unit and the speed difference after optimization, and taking the optimization of the primary frequency regulation action as the judgment condition; S3. Construct the primary frequency regulation contribution rate compensation logic, combine the primary frequency regulation contribution rate, and obtain the compensation coefficient of the primary frequency regulation contribution rate correction; when the primary frequency regulation of the unit is in action, this compensation coefficient forms a closed loop at the valve position factor compensation logic; S4, construct valve position factor compensation logic, the theoretical valve position factor is combined with the main steam pressure compensation coefficient, the power generation compensation coefficient, the total flow command compensation coefficient, the optimized speed difference compensation coefficient, the single-order valve switching compensation coefficient, and the primary frequency modulation contribution rate correction compensation coefficient to obtain the optimized valve position factor, and then the optimized valve position factor is input to the steam turbine DEH; S5. Construct the power factor compensation logic. The theoretical power factor is combined with the actual load of the unit, the unit load command and the optimized speed difference to obtain the power factor correction value. The corrected power factor acts on the steam turbine CCS.

[0007] Furthermore, the specific process in step S1 includes: S11, using three frequency transmitters to collect the high-voltage side frequencies of the three main transformers respectively, and converting the high-voltage side frequencies of the three main transformers into three unit speed signals respectively; S12, setting a first switching setting unit, wherein the initial value of the first switching setting unit is zero, and is set to one when the loop is switched to the optimized loop, and the outlet of the first switching setting unit is connected to the logic OR unit through the first logic NOT unit. In this step, when the speed signal of the unit participating in the primary frequency modulation is not put into the optimized primary frequency modulation loop, a high level signal is output to the logic OR unit, otherwise a low level signal is output to the logic OR unit; S13, set the bad point threshold, when there are two or more units whose speed signals are higher than the bad point threshold, the fault judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit; S14, set the deviation value. When the deviation value between the speed signals of the three units exceeds 3r / min, the deviation judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit; S15, set the speed limit range. When the average value of the three unit speed signals exceeds 3005r / min or is lower than 2995r / min, the limit judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit; S16, after the value of the speed signal of the three units is adjusted by the linear correction function, when the deviation from the value of the steam turbine speed signal of the original primary frequency modulation circuit of the unit exceeds 3r / min, a high level is output to the logic OR unit, otherwise a low level is output to the logic OR unit; S17, the output end of the logic OR unit is connected to a switching unit, and the switching unit is used to optimize the speed switching indication. When the output end of the logic OR unit outputs a high level, the switching unit will switch to the original primary frequency modulation circuit.

[0008] Furthermore, the specific process in step S2 includes: S21, input the actual load of the unit, the actual load of the unit is transmitted to the first calculation unit, and the actual load of the unit is also input to two delay functions f(t) of the unit respectively. The output ends of the two delay functions f(t) respectively output the actual load of the unit 1 second ago and the actual load 2 seconds ago to the first calculation unit. The first calculation unit outputs the average value of the actual load 3 seconds before a frequency modulation action; S22, the output end of the first calculation unit is connected to the input end N of the first selection unit, the input end Y of the first selection unit is connected to the output end, and the selection end of the first selection unit is input with the optimized primary frequency modulation action signal; wherein the first delay unit and the first delay off logic are connected between the input end of the optimized primary frequency modulation action signal and the selection end of the first selection unit; S23, the output end of the first selection unit is connected to the second calculation unit, the second calculation unit also inputs the actual load of the unit, and the actual load of the unit minus the average value of the actual load 3 seconds before the first frequency modulation action is obtained in the second calculation unit to obtain the current moment of power difference, that is, the integrated power of the unit at time T0 during the first frequency modulation process; the output end of the second calculation unit is connected to the input end Y of the second selection unit, the selection end of the second selection unit is connected to the optimization first frequency modulation action signal, the input signal received by the input end N of the second selection unit is zero, when the first frequency modulation action is performed, if the second selection unit outputs the current moment of power difference without, the second selection unit output is zero; S24, the current power difference value output by the second selection unit is multiplied by the controller scanning cycle 50ms to obtain the power difference value within the scanning cycle, and the power difference value is transmitted to the third calculation unit, and the output end of the third calculation unit outputs the current actual integrated power; in addition, a third selection unit is provided, the selection end of the third selection unit is connected to the optimization primary frequency modulation action signal, the input end Y of the third selection unit inputs the actual integrated power of the previous cycle, and the input end N of the third selection unit receives the input signal of zero; the output end of the third selection unit is connected to the third calculation unit; S25. When there is a speed difference during a primary frequency modulation action, the optimized speed difference is respectively input into the positive-to-positive standard unequal rate power function, the first height limiting unit and the negative-to-negative standard unequal rate power function, and the output result is connected to the input terminal Y, the selection terminal and the input terminal N of the fourth selection unit; when the first height limiting unit determines that the input speed difference is a positive number, the output value of the positive-to-positive standard unequal rate power function is output from the output value of the fourth selection unit; if the speed difference is a negative number, the output value of the negative-to-negative standard unequal rate power function is output from the output value of the fourth selection unit; the output terminal of the fourth selection unit is connected to the input terminal Y of the fifth selection unit, the input signal of the input terminal N of the fifth selection unit is infinitely small, and the selection terminal of the fifth selection unit is connected to the optimized primary frequency modulation action signal; when a primary frequency modulation action is performed, the output terminal of the fifth selection unit outputs the current theoretical power difference; S26, the theoretical power difference outputted from the output end of the fifth selection unit is multiplied by the controller scanning cycle 50ms to obtain the theoretical power difference within the scanning cycle, and the theoretical power difference of the current cycle is outputted to the fourth calculation unit, and the input end of the fourth calculation unit also inputs the theoretical integrated power of the previous cycle through the sixth selection unit; the output end of the fourth calculation unit outputs the theoretical integrated power of the current cycle; the current theoretical integrated power is also inputted to the input end Y of the sixth selection unit; the output end of the sixth selection unit is connected to the fourth calculation unit, and the input signal of the input end N of the sixth selection unit is infinitely small; S27. The actual integrated electricity is divided by the theoretical integrated electricity to obtain the primary frequency modulation contribution rate. The output end of the primary frequency modulation contribution rate is connected to the input end Y of the eighth selection unit. The selection end of the eighth selection unit is connected to the optimized primary frequency modulation action signal. The second delay unit and the second delay off logic are connected between the optimized primary frequency modulation action signal and the input end Y of the eighth selection unit. The output end of the eighth selection unit outputs the primary frequency modulation contribution rate.

[0009] Furthermore, the specific process in step S3 includes: S31, the primary frequency modulation contribution rate obtained in step S2 is respectively input to the selection end and the input end N of the ninth selection unit, wherein the second height limiting unit, the third delay unit and the third delay off logic are sequentially connected between the input end of the primary frequency modulation contribution rate and the selection end of the ninth selection unit, and the output end of the ninth selection unit outputs the input end Y setting value of the ninth selection unit; S32, the output end of the ninth selection unit is connected to the PID controller, and the output end of the PID controller is connected to the input end Y of the tenth selection unit; S33, the selection end of the tenth selection unit is logically connected to the optimization primary frequency modulation action signal through the fourth delay unit and the fourth delay switch, and the output end of the tenth selection unit outputs the primary frequency modulation contribution rate correction coefficient through the correction function.

[0010] Furthermore, the specific process in step S4 includes: S41, input the main steam pressure of the unit, the main steam pressure of the unit is connected to the selection end and the input end N of the eleventh selection unit through the quality judgment unit and the first-order inertia function respectively, the selection end Y of the eleventh selection unit is connected to the output end; the output end of the eleventh selection unit calculates the main steam pressure compensation coefficient through the broken line function; S42, input the generator power of the unit, the generator power of the unit is connected to the selection end and the input end N of the twelfth selection unit through the quality judgment unit and the first-order inertia function respectively, the selection end Y of the twelfth selection unit is connected to the output end; the output end of the twelfth selection unit calculates the generator power compensation coefficient of the unit through the broken line function; S43, inputting the total flow command of the unit, the power of the generator of the unit is connected to the selection end and the input end N of the thirteenth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the thirteenth selection unit is connected to the output end; the output end of the thirteenth selection unit calculates the compensation coefficient of the total flow command of the unit through the broken line function; S44, inputting the optimized speed difference, the optimized speed difference is connected to the selection end and the input end N of the fourteenth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the fourteenth selection unit is connected to the output end; the output end of the fourteenth selection unit calculates the optimized speed difference compensation coefficient through the broken line function and is connected to the input end N of the fifteenth selection unit, and the output end of the fifteenth selection unit outputs the optimized speed difference compensation coefficient; S45, input the unit single / sequential valve switching signal, the unit single / sequential valve switching signal is connected to the selection end of the sixteenth selection unit, the input end N and the input end Y of the sixteenth selection unit correspond to different compensation coefficient setting values, when the selection end of the sixteenth selection unit is the unit single / sequential valve switching signal, the output end outputs different compensation coefficients; S46. Multiply the theoretical valve position factor, the main steam pressure compensation coefficient, the unit generator power compensation coefficient, the unit total flow command compensation coefficient, the optimized speed difference compensation coefficient, the unit single / sequential valve switching signal and the primary frequency regulation contribution rate correction value to obtain the optimized valve position factor.

[0011] Furthermore, the specific process in step S5 includes: S51, inputting the unit load command to the input terminal N of the seventeenth selection unit, the input terminal Y of the seventeenth selection unit is connected to the output terminal, the selection terminal of the seventeenth selection unit is connected to the optimization primary frequency modulation action signal, and the output terminal of the seventeenth selection signal is connected to the fourth calculation unit; S52, input the actual load of the unit, filter it and input it to the input terminal N of the 18th selection unit, the input terminal Y of the 18th selection unit is connected to the output terminal, the selection terminal of the 18th selection unit is connected to the optimized primary frequency modulation action signal, and the output terminal of the 18th selection signal is connected to the fourth calculation unit; when the primary frequency modulation is in action, the output terminal of the 18th selection unit maintains the output value at the previous moment; when the primary frequency modulation is not in action, the output terminal of the 18th selection unit outputs the actual load of the unit; and then the load difference of the unit is obtained after passing through the fourth calculation unit; S53, the load difference of the unit is connected to the input terminal N and the input terminal Y of the nineteenth selection unit through two f(x), and the selection terminal of the nineteenth selection unit is connected to the theoretical power factor through the third height limiting unit; wherein the two f(x) are respectively a broken line function of increasing load and a broken line function of reducing load, the broken line function of increasing load is connected to the input terminal Y of the nineteenth selection unit, and the broken line function of reducing load is connected to the input terminal N of the nineteenth selection unit, and the output terminal of the nineteenth selection unit is connected to the input terminal Y of the twentieth selection unit; S54, the optimized primary frequency modulation action signal and the second switching setting unit are respectively connected to the logic AND unit, the input end of the optimized primary frequency modulation action signal is also provided with a fifth delay unit, one end of the output end of the fifth delay unit is directly connected to the logic AND unit, the output end of the fifth delay unit is also connected to the logic AND unit through the sixth delay unit and the second logic NOT unit, the output end of the logic AND unit is connected to the selection end of the twentieth selection unit, and the output end of the twentieth selection unit outputs the initial power deviation correction value; S55. Input the optimized speed difference into the power factor calculation unit for power factor calculation. The output value is connected to the input terminal Y of the seventh selection unit. The selection terminal of the seventh selection unit is connected to the output terminal of the logic AND unit. The output value of the seventh selection unit is connected to the fifth calculation unit. The initial power deviation correction value is also connected to the fifth calculation unit. The output terminal of the fifth calculation unit outputs the power factor correction value.

[0012] The beneficial effects of the present invention are: When the thermal power unit provided by the present invention performs primary frequency modulation, it can ensure that the unit valve does not act violently and that the primary frequency modulation theoretical action amount (valve position factor, power factor) meets relevant requirements; In the control method for improving the qualified rate of primary frequency modulation of thermal power units provided by the present invention, when a high-precision frequency signal involved in the primary frequency modulation fails, switching back to the original frequency modulation circuit of the unit can ensure the normal operation of the system and avoid frequency modulation failure or malfunction caused by frequency signal failure; when the optimized primary frequency modulation circuit is not put into use, switching back to the original frequency modulation circuit can prevent erroneous operation and ensure the stability and safety of the system; when two or more bad points appear in three frequency signals, switching back to the original frequency modulation circuit can reduce the influence of interference on the system and improve the anti-interference ability of the system; when there is a large deviation between the three frequency signals converted into the unit rotation speed, switching back to the original frequency modulation circuit can ensure the stability of the system and avoid unstable factors caused by excessive frequency signal deviation; when the value of the three frequency signals converted into the unit rotation speed after taking the center exceeds the set range, switching back to the original frequency modulation circuit can protect the equipment from the influence of too high or too low rotation speed and extend the service life of the equipment.

[0013] By setting the valve position factor compensation logic, power factor compensation logic, contribution rate calculation and compensation logic, the key parameters in the primary frequency regulation process can be compensated and adjusted, thereby improving the qualified rate of the primary frequency regulation action. By compensating for the frequency regulation power and speed deviation, the response capability of the primary frequency regulation can be enhanced, so that the unit can respond to the frequency regulation demand of the power grid more quickly and improve the regulation effect of the primary frequency regulation. By correcting the valve opening, proportional band parameters and integral time parameters corresponding to the primary frequency regulation load regulation by nonlinear parameters, the regulation quality of the coordinated control system can be improved, and the response time and response amplitude of the primary frequency regulation can be improved. By converting the frequency correction instruction into a nonlinear valve opening and directly superimposing it on the steam turbine main control feedforward channel, the reverse regulation problem caused by the primary frequency regulation steam turbine main control output lagging behind the valve position feedback can be solved, and the regulation effect of the primary frequency regulation can be improved. By compensating for the frequency regulation power and speed deviation, the regulation load of the primary frequency regulation can be increased to meet the load value required by the power grid, and the regulation effect of the primary frequency regulation can be improved.

[0014] The present invention provides a control method for improving the qualified rate of primary frequency regulation of thermal power units, which has the advantages of strong operability on the unit side and high safety on the unit side, so that the theoretical qualified rate of the primary frequency regulation of the thermal power units is higher and safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a signal source switching diagram of the present invention.

[0016] Figure 2 It is the valve position factor compensation diagram of the present invention.

[0017] Figure 3 It is a power factor compensation diagram of the present invention.

[0018] Figure 4 This is a calculation diagram of the primary frequency modulation contribution rate of the present invention.

[0019] Figure 5 It is a contribution rate compensation diagram of the present invention.

[0020] Figures indicate: 1: first selection unit, 2: second selection unit, 3: third selection unit, 4: fourth selection unit, 5: fifth selection unit, 6: sixth selection unit, 7: seventh selection unit, 8: eighth selection unit, 9: ninth selection unit, 10: tenth selection unit, 11: eleventh selection unit, 12: twelfth selection unit, 13: thirteenth selection unit, 14: fourteenth selection unit, 15: fifteenth selection unit, 16: sixteenth selection unit, 17: seventeenth selection unit, 18: eighteenth selection unit, 19: nineteenth selection unit, 20: twentieth selection unit; 21: first calculation unit, 22: second calculation unit, 23: third calculation unit, 24: fourth calculation unit, 25: fifth calculation unit, 26: first height limit unit, 27: second height limit unit, 28: third height limit unit, 29: first delay closing logic, 30: second delay closing logic, 31: third delay closing logic, 32: fourth delay closing logic, 33: first delay unit, 34: second delay unit, 35: third delay unit, 36: fourth delay unit, 37: fifth delay unit, 38: first switching setting unit, 39: second switching setting unit, 40: first logic negation unit, 41: second logic negation unit, 42: logic or unit, 43: switching unit, 44: quality judgment unit, 45: first-order inertia function, 46: sixth delay unit. DETAILED DESCRIPTION

[0021] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the embodiments and the accompanying drawings, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0022] Example: See Figure 1-Figure 5 The purpose of this embodiment is to provide a control method for improving the qualified rate of primary frequency regulation action of thermal power units, including steps S1-S5.

[0023] S1, such as Figure 1 As shown, frequency transmitters are installed on the high-voltage side of the three main transformers respectively, and the frequency signals collected by the frequency transmitters are converted into speed signals after the unit is connected to the grid, which are used to participate in the primary frequency regulation of the unit. When the speed signal participating in the primary frequency regulation after the unit is connected to the grid fails, it is switched back to the original primary frequency regulation circuit of the unit. When there is no failure, the current circuit is continued.

[0024] S2. Construct the calculation logic of the primary frequency regulation contribution rate of the unit. Figure 4As shown, by inputting the actual load of the unit and the speed difference after optimization, and taking the optimization of the primary frequency regulation action as the judgment condition, the primary frequency regulation contribution rate is obtained.

[0025] S3, construct the primary frequency modulation contribution rate compensation logic. Figure 5 As shown, combined with the primary frequency regulation contribution rate obtained in step S2, a compensation coefficient for correcting the primary frequency regulation contribution rate is obtained; when the unit is in primary frequency regulation action, this compensation coefficient forms a closed loop at the valve position factor compensation logic.

[0026] S4, construct valve position factor compensation logic. Figure 2 As shown in the figure, the theoretical valve position factor is combined with the main steam pressure compensation coefficient, the power generation compensation coefficient, the total flow command compensation coefficient, the optimized speed difference compensation coefficient, the single-valve switching compensation coefficient, and the primary frequency modulation contribution rate correction compensation coefficient to obtain the optimized valve position factor, and then the optimized valve position factor is applied to the steam turbine DEH to open the valve, close the valve or control the valve opening, thereby increasing or reducing the load.

[0027] S5, construct power factor compensation logic. Figure 3 As shown, the theoretical power factor is combined with the actual load of the unit, the unit load command and the optimized speed difference to obtain the power factor correction value. The corrected power factor acts on the steam turbine CCS or power control loop. When the corrected power factor shows that the system needs to increase the load, the CCS or power control loop will also adjust the valve opening of the steam turbine to increase the inflow of steam, thereby increasing the load. When the corrected power factor shows that the system needs to reduce the load, the CCS or power control loop adjusts the valve opening of the steam turbine to reduce the inflow of steam, thereby reducing the load.

[0028] In step S1, when the speed signal involved in the primary frequency regulation has one of the following faults, it switches back to the original primary frequency regulation circuit of the unit: 1) The optimized primary frequency modulation circuit has not been put into use; 2) Two or more of the three speed signals have bad points; 3) There is a deviation of more than 3r / min between the three converted speed signals; 4) The average value of the three converted speed signals exceeds 3005r / min or is lower than 2995r / min; 5) The average value of the three converted speed signals deviates from the speed signal value of the original primary frequency modulation circuit of the unit by more than 3r / min.

[0029] like Figure 1 As shown, the specific process in step S1 includes steps S11-S17.

[0030] S11. Use three frequency transmitters to collect the high-voltage side frequencies of the three main transformers respectively, and convert the high-voltage side frequencies of the three main transformers into three unit speed signals respectively.

[0031] S12. Set a first switching setting unit, wherein the initial value of the first switching setting unit is zero, and is set to one when the loop is switched to the optimized loop. The outlet of the first switching setting unit is connected to the logic OR unit through the first logic NOT unit. In this step, when the speed signal of the unit participating in the primary frequency modulation is not put into the optimized primary frequency modulation loop, a high level signal is output to the logic OR unit, otherwise a low level signal is output to the logic OR unit.

[0032] S13, set the bad point threshold. When there are two or more units whose speed signals are higher than the bad point threshold, the fault judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit.

[0033] S14, set the deviation constant. When the deviation between the speed signals of the three units exceeds 3r / min, the deviation judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit.

[0034] S15, set the speed limit range. When the average value of the speed signals of the three units exceeds 3005r / min or is lower than 2995r / min, the limit judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit.

[0035] S16. After the value of the speed signal of the three units is adjusted by the linear correction function, when the deviation from the value of the turbine speed signal of the original primary frequency modulation circuit of the unit exceeds 3r / min, a high level is output to the logic OR unit, otherwise a low level is output to the logic OR unit.

[0036] S17. The output end of the logic OR unit is connected to a switching unit, which is used to optimize the speed switching indication. When the output end of the logic OR unit outputs a high level, the switching unit will switch to the original primary frequency modulation circuit to ensure the safety and stability of the operation of the thermal power unit and avoid further failures.

[0037] like Figure 4 As shown, the specific process in step S2 includes steps S21-S27.

[0038] S21. Input the actual load of the unit. The actual load of the unit is transmitted to the first calculation unit. The actual load of the unit is also input into two delay functions f(t) of the unit respectively. The output ends of the two delay functions f(t) respectively output the actual load of the unit 1 second ago and the actual load 2 seconds ago to the first calculation unit. The first calculation unit outputs the average value of the actual load 3 seconds before a frequency modulation action.

[0039] S22, the output end of the first calculation unit is connected to the input end N of the first selection unit, the input end Y of the first selection unit is connected to the output end, and the selection end of the first selection unit inputs an optimization primary frequency modulation action signal; when there is a primary frequency modulation action, the output end of the first selection unit maintains the actual load average value 3 seconds before the primary frequency modulation action; wherein the first delay unit and the first delay off logic are connected between the input end of the optimization primary frequency modulation action signal and the selection end of the first selection unit.

[0040] S23. The output end of the first selection unit is connected to the second calculation unit. The actual load of the unit is also input into the second calculation unit. In the second calculation unit, the actual load of the unit is subtracted from the average actual load 3 seconds before the first frequency modulation action to obtain the current power difference, that is, the integrated power of the unit at time T0 during the first frequency modulation process; the output end of the second calculation unit is connected to the input end Y of the second selection unit. The selection end of the second selection unit is connected to the optimization signal of the first frequency modulation action. The input signal received by the input end N of the second selection unit is zero. When the first frequency modulation action is performed, the second selection unit outputs the current power difference; when the first frequency modulation action is not performed, the output of the second selection unit is zero.

[0041] S24, the current moment power difference value output by the second selection unit is multiplied by the controller scanning cycle 50ms to obtain the power difference value within the scanning cycle, and the power difference value is transmitted to the third calculation unit, and the output end of the third calculation unit outputs the current actual integrated power. In addition, a third selection unit is also provided, and the selection end of the third selection unit is connected to the optimization primary frequency modulation action signal, the input end Y of the third selection unit inputs the actual integrated power of the previous cycle, and the input signal received by the input end N of the third selection unit is zero. The output end of the third selection unit is connected to the third calculation unit, which is used to accumulate the integrated power accumulated in the previous cycle and the power difference obtained in the current scanning cycle to obtain the actual integrated power of the current cycle; when the primary frequency modulation is not in action, the currently accumulated integrated power is the actual integrated power; when the primary frequency modulation is still in action, the actual integrated power obtained in the current cycle is output to the third selection unit for the accumulation of the actual integrated power of the next cycle.

[0042] S25. If there is a speed difference during a primary frequency modulation action, the optimized speed difference will be input into the positive-to-positive standard unequal rate power function, the first height limit unit and the negative-to-negative standard unequal rate power function respectively, and the output results will be input into the input terminal Y, the selection terminal and the input terminal N of the fourth selection unit respectively; when the first height limit unit determines that the input speed difference is a positive number, the output value of the positive-to-positive standard unequal rate power function will be output from the output value of the fourth selection unit; if the speed difference is a negative number, the output value of the negative-to-negative standard unequal rate power function will be output from the output value of the fourth selection unit; the output terminal of the fourth selection unit is connected to the input terminal Y of the fifth selection unit, the input signal of the input terminal N of the fifth selection unit is infinitely small, and the selection terminal of the fifth selection unit is connected to the optimized primary frequency modulation action signal; when a primary frequency modulation action is performed, the output terminal of the fifth selection unit outputs the current theoretical power difference.

[0043] S26, the theoretical power difference outputted from the output end of the fifth selection unit is multiplied by the controller scanning cycle 50ms to obtain the theoretical power difference within the scanning cycle, and the theoretical power difference of the current cycle is outputted to the fourth calculation unit, and the input end of the fourth calculation unit also inputs the theoretical integrated power of the previous cycle through the sixth selection unit; the output end of the fourth calculation unit outputs the theoretical integrated power of the current cycle; the current theoretical integrated power is also inputted to the input end Y of the sixth selection unit. When a frequency modulation action is still in progress, the output end of the sixth selection unit inputs the current theoretical integrated power into the fourth calculation unit to accumulate the theoretical integrated power of the next cycle; the output end of the sixth selection unit is connected to the fourth calculation unit. The input signal of the input end N of the sixth selection unit is infinitely small, and is set to be infinitely small rather than zero in order to avoid false alarms when performing subsequent division operations.

[0044] S27, the actual integrated power is divided by the theoretical integrated power to obtain the primary frequency modulation contribution rate, the output end of the primary frequency modulation contribution rate is connected to the input end Y of the eighth selection unit, the selection end of the eighth selection unit is connected to the optimized primary frequency modulation action signal, the optimized primary frequency modulation action signal and the input end Y of the eighth selection unit are connected with the second delay unit and the second delay off logic; the output end of the eighth selection unit outputs the primary frequency modulation contribution rate. The second delay unit and the second delay off logic are set to delay the primary frequency modulation action for a while before closing, and reserve some time for the calculation of the current cycle to be completed.

[0045] like Figure 5 As shown, the specific process in step S3 includes steps S31-S33.

[0046] S31, the primary frequency modulation contribution rate obtained in step S2 is respectively input to the selection end and input end N of the ninth selection unit, wherein the second height limit unit, the third delay unit and the third delay off logic are connected in sequence between the input end of the primary frequency modulation contribution rate and the selection end of the ninth selection unit. The second height limit unit is used to determine whether the primary frequency modulation contribution rate is qualified. The value set on the second height limit unit can be set by technicians according to needs. When the primary frequency modulation contribution rate is qualified, the primary frequency modulation contribution rate does not exceed the limited amplitude of the second height limit unit, and at this time, the output end of the ninth selection unit outputs the actual value of the primary frequency modulation contribution rate; if the primary frequency modulation contribution rate exceeds the limited amplitude of the second height limit unit, the output end of the ninth selection unit outputs the input end Y setting value of the ninth selection unit.

[0047] S32, the output end of the ninth selection unit is connected to the PID controller, and the output end of the PID controller is connected to the input end Y of the tenth selection unit. If the primary frequency modulation contribution rate exceeds the limit amplitude of the second height limiting unit, the primary frequency modulation contribution rate is not adjusted on the PID controller; when the primary frequency modulation contribution rate does not exceed the limit amplitude of the second height limiting unit, the primary frequency modulation contribution rate is adjusted on the PID controller, and a compensation coefficient for correcting the primary frequency modulation contribution rate is output.

[0048] S33, the selection end of the tenth selection unit is logically connected to the optimization primary frequency modulation action signal through the fourth delay unit and the fourth delay switch, and the output end of the tenth selection unit outputs the primary frequency modulation contribution rate correction coefficient through the correction function.

[0049] like Figure 2 As shown, the specific process in step S4 includes steps S41-S46.

[0050] S41, input the main steam pressure of the unit, the main steam pressure of the unit is connected to the selection end and input end N of the eleventh selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the eleventh selection unit is connected to the output end. When the quality judgment unit judges that the main steam pressure is a bad point, the output end of the eleventh selection unit maintains the current value; when the main steam pressure is not a bad point, the output end of the eleventh selection unit outputs the value calculated by the first-order inertia function; the output end of the eleventh selection unit calculates the main steam pressure compensation coefficient through the broken line function.

[0051] The quality judgment unit determines the bad pixel based on the following: because the input of the thermal power unit in this logic is an analog input, its standard current range is 4 to 20 mA. The quality judgment unit can judge whether the input analog quantity is within the range according to the mA value. If it is not within the range, it is a bad pixel.

[0052] S42, input the generator power of the unit, the generator power of the unit is connected to the selection end and the input end N of the twelfth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the twelfth selection unit is connected to the output end; when the quality judgment unit judges that the generator power is a bad point, the output end of the twelfth selection unit maintains the current value; when the generator power is not a bad point, the output end of the twelfth selection unit outputs the value calculated by the first-order inertia function; the output end of the twelfth selection unit calculates the generator power compensation coefficient of the unit through the broken line function.

[0053] S43, input the total flow command of the unit, the generator power of the unit is connected to the selection end and the input end N of the thirteenth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the thirteenth selection unit is connected to the output end; when the quality judgment unit judges that the total flow command of the unit is a bad point, the output end of the thirteenth selection unit maintains the current value; when the total flow command of the unit is not a bad point, the output end of the thirteenth selection unit outputs the value calculated by the first-order inertia function; the output end of the thirteenth selection unit calculates the compensation coefficient of the total flow command of the unit through the broken line function.

[0054] S44, input the optimized speed difference, the optimized speed difference is connected to the selection end and input end N of the fourteenth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the fourteenth selection unit is connected to the output end; when the quality judgment unit judges that the optimized speed difference is a bad point, the output end of the fourteenth selection unit maintains the current value; when the optimized speed difference is not a bad point, the output end of the fourteenth selection unit outputs the value calculated by the first-order inertia function; the output end of the fourteenth selection unit calculates the optimized speed difference compensation coefficient through the broken line function, and is connected to the input end N of the fifteenth selection unit, and the output end of the fifteenth selection unit outputs the optimized speed difference compensation coefficient.

[0055] S45, input the unit single / sequential valve switching signal, the unit single / sequential valve switching signal is connected to the selection end of the sixteenth selection unit, the input end N and the input end Y of the sixteenth selection unit correspond to different compensation coefficient setting values, when the selection end of the sixteenth selection unit is the unit single / sequential valve switching signal, the output end outputs different compensation coefficients. When it is a single valve, the working mode of multiple valves is to open or close at the same time, so the working capacity will be stronger, and the output end of the sixteenth selection unit outputs the corresponding compensation coefficient; when it is a sequential valve, multiple valves are opened and closed in sequence, and the working capacity will be a little worse, so it will be reflected in the compensation coefficient. There will be changes, and at this time, the output end of the sixteenth selection unit will output the corresponding compensation coefficient when the valve is in sequence.

[0056] S46. Multiply the theoretical valve position factor, the main steam pressure compensation coefficient, the unit generator power compensation coefficient, the unit total flow command compensation coefficient, the optimized speed difference compensation coefficient, the unit single / sequential valve switching signal and the primary frequency regulation contribution rate correction value to obtain the optimized valve position factor. The optimized valve position factor is then applied to the DEH to adjust the valve opening.

[0057] like Figure 3 As shown, the specific process in step S5 includes steps S51-S55.

[0058] S51. Input the unit load command to the input terminal N of the seventeenth selection unit. The input terminal Y of the seventeenth selection unit is connected to the output terminal. The selection terminal of the seventeenth selection unit is connected to the optimized primary frequency modulation action signal. The output terminal of the seventeenth selection signal is connected to the fourth calculation unit.

[0059] S52, input the actual load of the unit, filter it and input it into the input terminal N of the eighteenth selection unit, the input terminal Y of the eighteenth selection unit is connected to the output terminal, the selection terminal of the eighteenth selection unit is connected to the optimized primary frequency modulation action signal, and the output terminal of the eighteenth selection signal is connected to the fourth calculation unit; when the primary frequency modulation is in action, the output terminal of the eighteenth selection unit maintains the output value of the previous moment; when the primary frequency modulation is not in action, the output terminal of the eighteenth selection unit outputs the actual load of the unit; and then the load difference of the unit is obtained after passing through the fourth calculation unit.

[0060] S53, the unit load difference is connected to the input terminal N and input terminal Y of the nineteenth selection unit through two f(x)s respectively, and the selection terminal of the nineteenth selection unit is connected to the theoretical power factor through the third height limiting unit; wherein the two f(x)s are respectively the broken line function of increasing load and the broken line function of reducing load, the broken line function of increasing load is connected to the input terminal Y of the nineteenth selection unit, and the broken line function of reducing load is connected to the input terminal N of the nineteenth selection unit, and the output terminal of the nineteenth selection unit is connected to the input terminal Y of the twentieth selection unit.

[0061] When the value of the theoretical power factor is higher than the third limiting unit, the output value of the broken line function for increasing the load is output from the nineteenth selection unit; when the value of the theoretical power factor is not higher than the third limiting unit, the output value of the broken line function for reducing the load is output from the nineteenth selection unit.

[0062] S54, the optimized primary frequency modulation action signal and the second switching setting unit are respectively connected to the logic AND unit, and a fifth delay unit is also arranged on the input end of the optimized primary frequency modulation action signal, and one end of the output end of the fifth delay unit is directly connected to the logic AND unit, and the output end of the fifth delay unit is also connected to the logic AND unit through the sixth delay unit and the second logic NOT unit, and the output end of the logic AND unit is connected to the selection end of the twentieth selection unit, and the output end of the twentieth selection unit outputs the initial power deviation correction value.

[0063] S55. Input the optimized speed difference into the power factor calculation unit for power factor calculation. The output value is connected to the input terminal Y of the seventh selection unit. The selection terminal of the seventh selection unit is connected to the output terminal of the logic AND unit. The output value of the seventh selection unit is connected to the fifth calculation unit. The initial power deviation correction value is also connected to the fifth calculation unit. The output terminal of the fifth calculation unit outputs the power factor correction value.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A control method for improving the qualified rate of primary frequency modulation action of thermal power units, characterized in that: Includes steps: S1. Install frequency transmitters on the high-voltage sides of the three main transformers respectively, convert the frequency signals collected by the frequency transmitters into speed signals after the unit is connected to the grid, and use them to participate in the primary frequency regulation of the unit. When the speed signal participating in the primary frequency regulation fails after the unit is connected to the grid, switch back to the original primary frequency regulation circuit of the unit; S2. Construct the calculation logic of the primary frequency regulation contribution rate of the unit, and obtain the primary frequency regulation contribution rate by inputting the actual load of the unit and the speed difference after optimization, and taking the optimization of the primary frequency regulation action as the judgment condition; S3. Construct the primary frequency regulation contribution rate compensation logic, combine the primary frequency regulation contribution rate, and obtain the compensation coefficient of the primary frequency regulation contribution rate correction; when the primary frequency regulation of the unit is in action, this compensation coefficient forms a closed loop at the valve position factor compensation logic; S4, construct valve position factor compensation logic, the theoretical valve position factor is combined with the main steam pressure compensation coefficient, the power generation compensation coefficient, the total flow command compensation coefficient, the optimized speed difference compensation coefficient, the single-order valve switching compensation coefficient, and the primary frequency modulation contribution rate correction compensation coefficient to obtain the optimized valve position factor, and then the optimized valve position factor is input to the steam turbine DEH; S5. Construct the power factor compensation logic. The theoretical power factor is combined with the actual load of the unit, the unit load command and the optimized speed difference to obtain the power factor correction value. The corrected power factor acts on the steam turbine CCS.

2. A control method for improving the qualified rate of primary frequency modulation of thermal power units according to claim 1, characterized in that: The specific process in step S1 includes: S11, using three frequency transmitters to collect the high-voltage side frequencies of the three main transformers respectively, and converting the high-voltage side frequencies of the three main transformers into three unit speed signals respectively; S12, setting a first switching setting unit, wherein the initial value of the first switching setting unit is zero, and is set to one when the loop is switched to the optimized loop, and the outlet of the first switching setting unit is connected to the logic OR unit through the first logic NOT unit. In this step, when the speed signal of the unit participating in the primary frequency modulation is not put into the optimized primary frequency modulation loop, a high level signal is output to the logic OR unit, otherwise a low level signal is output to the logic OR unit; S13, set the bad point threshold, when there are two or more units whose speed signals are higher than the bad point threshold, the fault judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit; S14, set the deviation value. When the deviation value between the speed signals of the three units exceeds 3r / min, the deviation judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit; S15, set the speed limit range. When the average value of the three unit speed signals exceeds 3005r / min or is lower than 2995r / min, the limit judgment interface outputs a high level to the logic OR unit, otherwise it outputs a low level to the logic OR unit; S16, after the value of the speed signal of the three units is adjusted by the linear correction function, when the deviation from the value of the steam turbine speed signal of the original primary frequency modulation circuit of the unit exceeds 3r / min, a high level is output to the logic OR unit, otherwise a low level is output to the logic OR unit; S17, the output end of the logic OR unit is connected to a switching unit, and the switching unit is used to optimize the speed switching indication. When the output end of the logic OR unit outputs a high level, the switching unit will switch to the original primary frequency modulation circuit.

3. A control method for improving the qualified rate of primary frequency modulation of thermal power units according to claim 2, characterized in that: The specific process in step S2 includes: S21, input the actual load of the unit, the actual load of the unit is transmitted to the first calculation unit, and the actual load of the unit is also input to two delay functions f(t) of the unit respectively. The output ends of the two delay functions f(t) respectively output the actual load of the unit 1 second ago and the actual load 2 seconds ago to the first calculation unit. The first calculation unit outputs the average value of the actual load 3 seconds before a frequency modulation action; S22, the output end of the first calculation unit is connected to the input end N of the first selection unit, the input end Y of the first selection unit is connected to the output end, and the selection end of the first selection unit is input with the optimized primary frequency modulation action signal; wherein the first delay unit and the first delay off logic are connected between the input end of the optimized primary frequency modulation action signal and the selection end of the first selection unit; S23, the output end of the first selection unit is connected to the second calculation unit, the second calculation unit also inputs the actual load of the unit, and the actual load of the unit minus the average value of the actual load 3 seconds before the first frequency modulation action is obtained in the second calculation unit to obtain the current moment of power difference, that is, the integrated power of the unit at time T0 during the first frequency modulation process; the output end of the second calculation unit is connected to the input end Y of the second selection unit, the selection end of the second selection unit is connected to the optimization first frequency modulation action signal, the input signal received by the input end N of the second selection unit is zero, when the first frequency modulation action is performed, if the second selection unit outputs the current moment of power difference without, the second selection unit output is zero; S24, the current power difference value output by the second selection unit is multiplied by the controller scanning cycle 50ms to obtain the power difference value within the scanning cycle, and the power difference value is transmitted to the third calculation unit, and the output end of the third calculation unit outputs the current actual integrated power; in addition, a third selection unit is provided, the selection end of the third selection unit is connected to the optimization primary frequency modulation action signal, the input end Y of the third selection unit inputs the actual integrated power of the previous cycle, and the input end N of the third selection unit receives the input signal of zero; the output end of the third selection unit is connected to the third calculation unit; S25. When there is a speed difference during a primary frequency modulation action, the optimized speed difference is respectively input into the positive-to-positive standard unequal rate power function, the first height limiting unit and the negative-to-negative standard unequal rate power function, and the output result is connected to the input terminal Y, the selection terminal and the input terminal N of the fourth selection unit; when the first height limiting unit determines that the input speed difference is a positive number, the output value of the positive-to-positive standard unequal rate power function is output from the output value of the fourth selection unit; if the speed difference is a negative number, the output value of the negative-to-negative standard unequal rate power function is output from the output value of the fourth selection unit; the output terminal of the fourth selection unit is connected to the input terminal Y of the fifth selection unit, the input signal of the input terminal N of the fifth selection unit is infinitely small, and the selection terminal of the fifth selection unit is connected to the optimized primary frequency modulation action signal; when a primary frequency modulation action is performed, the output terminal of the fifth selection unit outputs the current theoretical power difference; S26, the theoretical power difference outputted from the output end of the fifth selection unit is multiplied by the controller scanning cycle 50ms to obtain the theoretical power difference within the scanning cycle, and the theoretical power difference of the current cycle is outputted to the fourth calculation unit, and the input end of the fourth calculation unit also inputs the theoretical integrated power of the previous cycle through the sixth selection unit; the output end of the fourth calculation unit outputs the theoretical integrated power of the current cycle; the current theoretical integrated power is also inputted to the input end Y of the sixth selection unit; the output end of the sixth selection unit is connected to the fourth calculation unit, and the input signal of the input end N of the sixth selection unit is infinitely small; S27. The actual integrated electricity is divided by the theoretical integrated electricity to obtain the primary frequency modulation contribution rate. The output end of the primary frequency modulation contribution rate is connected to the input end Y of the eighth selection unit. The selection end of the eighth selection unit is connected to the optimized primary frequency modulation action signal. The second delay unit and the second delay off logic are connected between the optimized primary frequency modulation action signal and the input end Y of the eighth selection unit. The output end of the eighth selection unit outputs the primary frequency modulation contribution rate.

4. A control method for improving the qualified rate of primary frequency modulation of thermal power units according to claim 3, characterized in that: The specific process in step S3 includes: S31, the primary frequency modulation contribution rate obtained in step S2 is respectively input to the selection end and the input end N of the ninth selection unit, wherein the second height limiting unit, the third delay unit and the third delay off logic are sequentially connected between the input end of the primary frequency modulation contribution rate and the selection end of the ninth selection unit, and the output end of the ninth selection unit outputs the input end Y setting value of the ninth selection unit; S32, the output end of the ninth selection unit is connected to the PID controller, and the output end of the PID controller is connected to the input end Y of the tenth selection unit; S33, the selection end of the tenth selection unit is logically connected to the optimization primary frequency modulation action signal through the fourth delay unit and the fourth delay switch, and the output end of the tenth selection unit outputs the primary frequency modulation contribution rate correction coefficient through the correction function.

5. A control method for improving the qualified rate of primary frequency modulation of thermal power units according to claim 4, characterized in that: The specific process in step S4 includes: S41, input the main steam pressure of the unit, the main steam pressure of the unit is connected to the selection end and the input end N of the eleventh selection unit through the quality judgment unit and the first-order inertia function respectively, the selection end Y of the eleventh selection unit is connected to the output end; the output end of the eleventh selection unit calculates the main steam pressure compensation coefficient through the broken line function; S42, input the generator power of the unit, the generator power of the unit is connected to the selection end and the input end N of the twelfth selection unit through the quality judgment unit and the first-order inertia function respectively, the selection end Y of the twelfth selection unit is connected to the output end; the output end of the twelfth selection unit calculates the generator power compensation coefficient of the unit through the broken line function; S43, inputting the total flow command of the unit, the power of the generator of the unit is connected to the selection end and the input end N of the thirteenth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the thirteenth selection unit is connected to the output end; the output end of the thirteenth selection unit calculates the compensation coefficient of the total flow command of the unit through the broken line function; S44, inputting the optimized speed difference, the optimized speed difference is connected to the selection end and the input end N of the fourteenth selection unit through the quality judgment unit and the first-order inertia function respectively, and the selection end Y of the fourteenth selection unit is connected to the output end; the output end of the fourteenth selection unit calculates the optimized speed difference compensation coefficient through the broken line function and is connected to the input end N of the fifteenth selection unit, and the output end of the fifteenth selection unit outputs the optimized speed difference compensation coefficient; S45, input the unit single / sequential valve switching signal, the unit single / sequential valve switching signal is connected to the selection end of the sixteenth selection unit, the input end N and the input end Y of the sixteenth selection unit correspond to different compensation coefficient setting values, when the selection end of the sixteenth selection unit is the unit single / sequential valve switching signal, the output end outputs different compensation coefficients; S46. Multiply the theoretical valve position factor, the main steam pressure compensation coefficient, the unit generator power compensation coefficient, the unit total flow command compensation coefficient, the optimized speed difference compensation coefficient, the unit single / sequential valve switching signal and the primary frequency regulation contribution rate correction value to obtain the optimized valve position factor.

6. A control method for improving the qualified rate of primary frequency modulation of thermal power units according to claim 5, characterized in that: The specific process in step S5 includes: S51, inputting the unit load command to the input terminal N of the seventeenth selection unit, the input terminal Y of the seventeenth selection unit is connected to the output terminal, the selection terminal of the seventeenth selection unit is connected to the optimization primary frequency modulation action signal, and the output terminal of the seventeenth selection signal is connected to the fourth calculation unit; S52, input the actual load of the unit, filter it and input it to the input terminal N of the 18th selection unit, the input terminal Y of the 18th selection unit is connected to the output terminal, the selection terminal of the 18th selection unit is connected to the optimized primary frequency modulation action signal, and the output terminal of the 18th selection signal is connected to the fourth calculation unit; when the primary frequency modulation is in action, the output terminal of the 18th selection unit maintains the output value at the previous moment; when the primary frequency modulation is not in action, the output terminal of the 18th selection unit outputs the actual load of the unit; and then the load difference of the unit is obtained after passing through the fourth calculation unit; S53, the load difference of the unit is connected to the input terminal N and the input terminal Y of the nineteenth selection unit through two f(x), and the selection terminal of the nineteenth selection unit is connected to the theoretical power factor through the third height limiting unit; wherein the two f(x) are respectively a broken line function of increasing load and a broken line function of reducing load, the broken line function of increasing load is connected to the input terminal Y of the nineteenth selection unit, and the broken line function of reducing load is connected to the input terminal N of the nineteenth selection unit, and the output terminal of the nineteenth selection unit is connected to the input terminal Y of the twentieth selection unit; S54, the optimized primary frequency modulation action signal and the second switching setting unit are respectively connected to the logic AND unit, the input end of the optimized primary frequency modulation action signal is also provided with a fifth delay unit, one end of the output end of the fifth delay unit is directly connected to the logic AND unit, the output end of the fifth delay unit is also connected to the logic AND unit through the sixth delay unit and the second logic NOT unit, the output end of the logic AND unit is connected to the selection end of the twentieth selection unit, and the output end of the twentieth selection unit outputs the initial power deviation correction value; S55. Input the optimized speed difference into the power factor calculation unit for power factor calculation. The output value is connected to the input terminal Y of the seventh selection unit. The selection terminal of the seventh selection unit is connected to the output terminal of the logic AND unit. The output value of the seventh selection unit is connected to the fifth calculation unit. The initial power deviation correction value is also connected to the fifth calculation unit. The output terminal of the fifth calculation unit outputs the power factor correction value.

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