A feedwater control method and device for deep peak shaving of a circulating fluidized bed unit

Abstract

The embodiment of the present application provides a kind of circulating fluidized bed unit depth peak shaving water supply control method and device, the method comprises: according to primary frequency modulation instruction, amplitude limiting and speed limiting after load instruction, power generation load, heating load and actual water supply flow, based on first PID processing process, determine basic water supply instruction;According to superheat related information, amplitude limiting and speed limiting after load instruction, load total instruction, variable load information, main gas temperature feedback and set information, and flue gas recirculation information, based on second PID processing process, determine feedback water supply instruction;According to the basic water supply instruction, coal quantity information, amplitude limiting and speed limiting after load instruction, main steam pressure information, boiler main control feedforward and fuel main control feedforward, determine feedforward water supply instruction;The basic water supply instruction, the feedback water supply instruction and the feedforward water supply instruction are summed to obtain total water supply instruction;According to total water supply instruction control circulating fluidized bed unit depth peak shaving under water supply.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal power plant automatic control, in particular to a feedwater control method and device for deep load following of a circulating fluidized bed unit. BACKGROUND

[0002] The basic principle of the existing feedwater control scheme for the circulating fluidized bed unit is to add a feedback feedwater instruction to a basic feedwater instruction. In the existing scheme, the basic feedwater instruction is calculated by an LDC; in the calculation logic of the feedback feedwater instruction, the proportion and integral of a PID module are fixed values.

[0003] In the process of implementing the present application, the applicant found at least the following problems in the prior art:

[0004] The feedwater flow is inaccurate, and when the main steam temperature feedback and set deviation are large, the feedwater flow needs to be manually intervened by an operator, and the feedwater instruction cannot be adjusted according to the unit load. SUMMARY

[0005] The embodiments of the present application provide a feedwater control method and device for deep load following of a circulating fluidized bed unit, which is also a feedwater master front feed control method and device for deep load following of a circulating fluidized bed unit, and solve the problem of inaccurate feedwater flow, which needs to be manually intervened by an operator when the main steam temperature feedback and set deviation are large, and the feedwater instruction cannot be adjusted according to the unit load.

[0006] To achieve the above purpose, on the one hand, the embodiments of the present application provide a feedwater control method for deep load following of a circulating fluidized bed unit, comprising:

[0007] determining a basic feedwater instruction based on a first PID processing process according to a primary frequency modulation instruction, a post-amplitude limiting and speed limiting load instruction, a power generation load, a heat supply load and an actual feedwater flow;

[0008] determining a feedback feedwater instruction based on a second PID processing process according to superheat degree related information, the post-amplitude limiting and speed limiting load instruction, a total load instruction, variable load information, main steam temperature feedback and set information, and flue gas recirculation information;

[0009] determining a front feed feedwater instruction according to the basic feedwater instruction, coal quantity information, the post-amplitude limiting and speed limiting load instruction, main steam pressure information, a boiler master front feed and a fuel master front feed;

[0010] summing the basic feedwater instruction, the feedback feedwater instruction and the front feed feedwater instruction to obtain a total feedwater instruction;

[0011] controlling the feedwater under deep load following of the circulating fluidized bed unit according to the total feedwater instruction.

[0012] In another aspect, the embodiment of the present application provides a feedwater control device for deep peak shaving of a circulating fluidized bed unit, comprising:

[0013] a basic feedwater instruction determination unit configured to determine a basic feedwater instruction based on a first PID processing procedure according to a primary frequency modulation instruction, a post-amplitude limiting and speed limiting load instruction, a power generation load, a heat supply load, and an actual feedwater flow rate;

[0014] a feedback feedwater instruction determination unit configured to determine a feedback feedwater instruction based on a second PID processing procedure according to superheat degree related information, the post-amplitude limiting and speed limiting load instruction, a total load instruction, variable load information, main gas temperature feedback and setting information, and flue gas recirculation information;

[0015] a feedforward feedwater instruction determination unit configured to determine a feedforward feedwater instruction according to the basic feedwater instruction, coal quantity information, the post-amplitude limiting and speed limiting load instruction, main steam pressure information, boiler main control feedforward, and fuel main control feedforward;

[0016] a total feedwater instruction determination unit configured to sum the basic feedwater instruction, the feedback feedwater instruction, and the feedforward feedwater instruction to obtain a total feedwater instruction;

[0017] a feedwater control unit configured to control feedwater under deep peak shaving of the circulating fluidized bed unit according to the total feedwater instruction.

[0018] The above technical solution has the following beneficial effects: the total feedwater instruction is obtained by adding the basic feedwater instruction, the feedback feedwater instruction, and the feedforward feedwater instruction, which can ensure that the feedwater flow rate changes in time during a variable load stage, and at the same time, the coal quality change, the intermediate point temperature fluctuation, the flue gas recirculation input, and the like are taken into account, and the feedwater flow rate can be kept stable during the deep peak shaving stage. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0020] Figure 1 is a flow chart of a feedwater control method for deep peak shaving of a circulating fluidized bed unit according to an embodiment of the present application;

[0021] Figure 2 is an architecture diagram of a feedwater control device for deep peak shaving of a circulating fluidized bed unit according to an embodiment of the present application;

[0022] Figure 3A principle diagram for determining total water supply instruction of a water supply control device for deep peak regulation of a circulating fluidized bed unit based on NT6000 system implementation is one of the embodiments of the present application;

[0023] Figure 4 A principle diagram for determining basic water supply instruction of a water supply control device for deep peak regulation of a circulating fluidized bed unit based on NT6000 system implementation is one of the embodiments of the present application;

[0024] Figure 5 A principle diagram for determining feedback water supply instruction of a water supply control device for deep peak regulation of a circulating fluidized bed unit based on NT6000 system implementation is one of the embodiments of the present application;

[0025] Figure 6 A principle diagram for determining feedforward water supply instruction of a water supply control device for deep peak regulation of a circulating fluidized bed unit based on NT6000 system implementation is one of the embodiments of the present application.

[0026] The reference signs are shown as follows: 11-15, one-to-one corresponding to the first summation module to the fifth summation module, 10, the tenth summation module; 21-28, one-to-one corresponding to the first inertia filtering module to the eighth inertia filtering module; 31-37, one-to-one corresponding to the first multiplication module to the seventh multiplication module; 41-49, one-to-one corresponding to the first conversion module to the ninth conversion module; 4A, the tenth conversion module; 4B, the eleventh conversion module; 4C, the twelfth conversion module; 4D, the thirteenth conversion module; 4E, the fourteenth conversion module, 4F, the fifteenth conversion module; 51-58, one-to-one corresponding to the first difference module to the eighth difference module 58; 61-64, one-to-one corresponding to the first selection module to the fourth selection module; 71, the first comparison module; 72, the second comparison module; 81, the first PID processing module; 82, the second PID processing module; 91, the first division module; 92, the second division module; 93, the third division module 93; 1, the first AND module; 2, the first maximum value acquisition module; 621, the proportional parameter selection module; 622, the integral parameter selection module. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only 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 skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] In one aspect, as shown in Figure 1 the embodiments of the present application provide a water supply control method for deep peak regulation of a circulating fluidized bed unit, comprising:

[0029] In step S100, a basic feedwater instruction is determined based on a first PID processing procedure according to a primary frequency modulation instruction, an amplitude-limited and speed-limited post-load instruction, a power generation load, a heat supply load and an actual feedwater flow rate;

[0030] In step S101, a feedback feedwater instruction is determined based on a second PID processing procedure according to superheat degree related information, the amplitude-limited and speed-limited post-load instruction, a total load instruction, variable load information, main gas temperature feedback and setting information and flue gas recirculation information;

[0031] In step S102, a feedforward feedwater instruction is determined according to the basic feedwater instruction, coal quantity information, the amplitude-limited and speed-limited post-load instruction, main steam pressure information, a boiler main control feedforward and a fuel main control feedforward;

[0032] In step S103, the basic feedwater instruction, the feedback feedwater instruction and the feedforward feedwater instruction are summed to obtain a total feedwater instruction;

[0033] In step S104, the total feedwater instruction is used to control feedwater under deep peak shaving of a circulating fluidized bed unit.

[0034] In some embodiments, the final feedwater instruction, i.e., the total feedwater instruction, is obtained by adding three parts: a first part is a basic feedwater instruction generated by a load instruction; a second part is a feedback feedwater instruction corrected by superheat degree; and a third part is a feedforward feedwater instruction formed by superimposing four feedforwards of a boiler main control feedforward, a fuel main control feedforward, main steam pressure and a unit load to a feedwater main control.

[0035] The embodiment of the present application has the following technical effects: the feedwater flow rate can be changed in time during a variable load stage of the unit, while taking into account coal quality change, intermediate point temperature fluctuation, flue gas recirculation input and the like, and the feedwater flow rate can be kept stable during a deep peak shaving stage of the unit.

[0036] Further, the basic feedwater instruction is determined based on a first PID processing procedure according to a primary frequency modulation instruction, an amplitude-limited and speed-limited post-load instruction, a power generation load, a heat supply load and an actual feedwater flow rate, and includes:

[0037] The basic feedwater flow rate is determined according to the primary frequency modulation instruction and the amplitude-limited and speed-limited post-load instruction;

[0038] A current feedwater correction coefficient is determined based on the first PID processing procedure according to the power generation load, the heat supply load and the actual feedwater flow rate;

[0039] The basic feedwater flow rate is divided by the current feedwater correction coefficient to obtain the basic feedwater instruction.

[0040] In some embodiments, the calculation logic of the feedwater BTU coefficient (i.e., the feedwater correction coefficient) is increased compared with the conventional scheme; the basic feedwater flow generated by the primary frequency modulation instruction and the limited speed after load is divided by the feedwater BTU coefficient to obtain the basic feedwater instruction. The role of the feedwater BTU coefficient is to make the basic feedwater instruction calculation more accurate, and the obtained instruction can more accurately meet the current working condition demand for feedwater.

[0041] Further, the basic feedwater flow is determined according to the primary frequency modulation instruction and the limited speed after load instruction, comprising:

[0042] The basic total load is determined according to the primary frequency modulation instruction and the limited speed after load instruction;

[0043] The basic total load is input into a first conversion function to obtain the basic feedwater flow.

[0044] In some embodiments, the basic total load is determined according to the primary frequency modulation instruction and the limited speed after load instruction, specifically, the primary frequency modulation instruction is multiplied by a preset constant after the seventh inertia filtering, and then added to the limited speed after load instruction to obtain the basic total load; the basic total load is input into a first conversion function to obtain the basic feedwater flow. The first conversion function and the second conversion function are both for converting load into feedwater flow; preferably, the input and output range of the second conversion function is greater than that of the first conversion function.

[0045] Further, the current feedwater correction coefficient is determined based on the first PID processing process according to the power generation load, the heating load and the actual feedwater flow, comprising:

[0046] The power generation load and the heating load are added to obtain a power generation and heating load;

[0047] The power generation and heating load is input into a second conversion function to obtain a predicted feedwater flow;

[0048] The actual feedwater flow is subjected to first inertia filtering to obtain an inertia filtered feedwater flow;

[0049] The inertia filtered feedwater flow is multiplied by a feedwater correction coefficient feedback value to obtain a corrected feedwater flow;

[0050] The predicted feedwater flow is subtracted from the corrected feedwater flow to obtain a feedwater flow difference;

[0051] It is judged whether the actual feedwater flow is less than a preset flow threshold value;

[0052] If the actual feedwater flow is less than the preset flow threshold value, the first PID flow difference is set to 0, otherwise the feedwater flow difference is taken as the first PID flow difference;

[0053] inputting the first PID flow difference as a set value of the first PID process into the first PID process, inputting an output control quantity of the first PID process into the third conversion function, and updating the current feedwater correction coefficient using an output value of the third conversion function;

[0054] wherein the feedwater correction coefficient feedback value is a current feedwater correction coefficient obtained when performing the step of multiplying the inertia-filtered feedwater flow by the feedwater correction coefficient feedback value to obtain a corrected feedwater flow;

[0055] wherein the first PID process includes a current sampling value, a set value, a proportional gain, an integral gain, a differential gain, and an output control quantity.

[0056] In some embodiments, the feedwater correction coefficient (feedwater BTU coefficient) is determined based on a first PID process according to a power generation load, a heat supply load, and an actual feedwater flow. Specifically, when the actual feedwater flow is less than a preset flow threshold, the current feedwater correction coefficient is maintained by inputting a value of 0 to the current sampling value of the first PID process; and when the actual feedwater flow is greater than or equal to the preset flow threshold, the current feedwater correction coefficient is updated by inputting the feedwater flow difference to the current sampling value of the first PID process. The preset flow threshold is preferably 160 t / h (ton / hour), the current sampling value in the first PID process is 0, the proportional gain is 0, the integral gain is 3600, and the third conversion function can be a preset piecewise function for converting the output control quantity of the first PID process into the feedwater BTU coefficient (feedwater correction coefficient).

[0057] The embodiments of the present application have the following technical effects: compared with the conventional scheme, the calculation logic of the feedwater BTU coefficient (i.e. the feedwater correction coefficient) is increased; the basic feedwater flow generated from the primary frequency modulation instruction and the limited load is divided by the feedwater BTU coefficient to obtain the basic feedwater instruction. Moreover, considering the deep peak shaving condition, the logic of stopping updating the feedwater BTU coefficient when the feedwater flow is less than the preset flow threshold is added to avoid triggering the minimum protection of the feedwater flow. Preferably, when the feedwater flow is less than 160 t / h, the calculation of the feedwater BTU coefficient is not needed in this working condition.

[0058] Further, the superheat degree related information includes a superheat degree and a superheat degree set bias;

[0059] The main steam temperature feedback and set information includes a left main steam temperature feedback, a left main steam temperature set, a right main steam temperature feedback, and a right main steam temperature set.

[0060] The flue gas recirculation information includes: flue gas recirculation air volume and flue gas recirculation input information;

[0061] The second PID processing process includes: current sampling value, set value, proportional gain, integral gain, differential gain, feedforward bias and output control quantity;

[0062] The determination of the feedback water command according to the superheat degree related information, the limited-amplitude and limited-speed load command, the total load command, the variable load information, the main gas temperature feedback and setting information, and the flue gas recirculation information includes:

[0063] The limited-amplitude and limited-speed load command is subjected to second inertia filtering to obtain a second filtered limited-amplitude and limited-speed load command;

[0064] The second filtered limited-amplitude and limited-speed load command is converted by a fourth conversion function to obtain a predicted superheat degree;

[0065] The predicted superheat degree is added to the superheat degree set bias to obtain a biased predicted superheat degree;

[0066] The biased predicted superheat degree is input to the second PID processing process as a set value of the second PID processing process;

[0067] The superheat degree is input to the second PID processing process as a current sampling value of the second PID processing process;

[0068] The total load command is subjected to a fifth conversion function to obtain a first proportional parameter;

[0069] The total load command is subjected to a sixth conversion function to obtain a second proportional parameter;

[0070] The total load command is subjected to a seventh conversion function to obtain a first integral parameter;

[0071] The total load command is subjected to an eighth conversion function to obtain a second integral parameter;

[0072] Whether the variable load information indicates a variable load is determined;

[0073] If the variable load information indicates a variable load, the first proportional parameter and the first integral parameter are respectively taken as a PID proportional parameter and a PID integral parameter;

[0074] If the variable load information does not indicate a variable load, the second proportional parameter and the second integral parameter are respectively taken as a PID proportional parameter and a PID integral parameter;

[0075] The PID proportional parameter and the PID integral parameter are respectively input to the second PID processing process as a proportional gain and an integral gain of the second PID processing process;

[0076] subtracting the left main steam temperature set value from the left main steam temperature feedback to obtain a left main steam temperature difference value;

[0077] subtracting the right main steam temperature set value from the right main steam temperature feedback to obtain a right main steam temperature difference value;

[0078] comparing the left main steam temperature difference value and the right main steam temperature difference value, and taking the larger value as a main steam temperature difference value;

[0079] obtaining a first predicted superheat difference initial value through a ninth conversion function from the main steam temperature difference value;

[0080] obtaining a second predicted superheat difference initial value through a tenth conversion function from the main steam temperature difference value;

[0081] judging whether the main steam temperature difference value is greater than zero;

[0082] if the main steam temperature difference value is greater than zero, taking the first predicted superheat difference initial value as a first predicted superheat difference value, otherwise taking the second predicted superheat difference initial value as the first predicted superheat difference value;

[0083] if the main steam temperature difference value is greater than 0, taking the first predicted superheat difference initial value obtained through the ninth conversion function as the first predicted superheat difference value, the input main steam temperature difference value of the ninth conversion function is greater than 0, and the output of the ninth conversion function is also greater than 0; if the main steam temperature difference value is less than or equal to 0, taking the second predicted superheat difference initial value obtained through the tenth conversion function as the first predicted superheat difference value, the input main steam temperature difference value of the tenth conversion function is less than or equal to 0, and the output of the tenth conversion function is also less than or equal to 0;

[0084] obtaining a filtered flue gas recirculation air volume through third inertial filtering of the flue gas recirculation air volume;

[0085] obtaining a twice-inertially filtered flue gas recirculation air volume through fourth inertial filtering of the filtered flue gas recirculation air volume;

[0086] obtaining a third predicted superheat difference initial value through an eleventh conversion function from a difference value obtained by subtracting the twice-inertially filtered flue gas recirculation air volume from the filtered flue gas recirculation air volume;

[0087] obtaining a fourth predicted superheat difference initial value through a twelfth conversion function from the filtered flue gas recirculation air volume;

[0088] adding the third predicted superheat difference initial value and the fourth predicted superheat difference initial value to obtain a fifth predicted superheat difference initial value;

[0089] judging whether the flue gas recirculation input information is input flue gas recirculation;

[0090] If the flue gas recirculation input information is input flue gas recirculation, the fifth predicted superheat difference initial value is taken as the second predicted superheat difference value; otherwise, 0 is taken as the second predicted superheat difference value;

[0091] The first predicted superheat difference value is subtracted by the second predicted superheat difference value to obtain a PID bias;

[0092] The PID bias is input to a feedforward bias of a second PID process;

[0093] An output control quantity of the second PID process is taken as the feedback water instruction;

[0094] Wherein, the fifth conversion function obtains a proportional parameter under variable load, the sixth conversion function obtains a proportional parameter under constant load, the seventh conversion function obtains an integral parameter under variable load, and the eighth conversion function obtains an integral parameter under constant load.

[0095] In some embodiments, the input of the feedback water instruction logic determination includes superheat, LDC (i.e. limited load instruction), MT_BIAS (i.e. superheat setting bias), total load instruction, variable load information, left side steam temperature feedback, left side steam temperature setting, right side steam temperature feedback, right side steam temperature setting, flue gas recirculation air volume and flue gas recirculation input information. The logic contains two parts: the first part takes the input superheat as the current sampling value of the second PID process, and takes the predicted superheat after bias determined according to LDC and superheat setting bias as the set value of the second PID process, and calculates the feedback water instruction through the PID module. At the same time, the proportional gain and integral gain of the PID module are not set as constants, but are set according to the state of whether the unit load is variable under the variable load information, and at the same time, the variable load state is also processed by segmented variable parameters according to the total load instruction. Different proportional gain and integral gain are used under variable load and constant load, and the specific proportional gain and integral gain are determined according to the total load instruction; the second part adds a feedforward quantity (feedforward bias) to the second PID process, the feedforward bias is used to directly superimpose on the conventional PID calculation result, which is equivalent to adding the value of the feedforward bias to the influence result of the PID processing calculation of the proportional, integral and / or differential as the final PID output result. The determination of the feedforward bias mainly considers the influence of the main steam temperature and the flue gas recirculation, and the main steam temperature takes the larger one of the feedback and setting deviation of the left and right sides to calculate.

[0096] The embodiment of the present application has the following technical effects: the proportion and integration of the traditional PID module are fixed values, which do not change with the total load command, resulting in poor adjustment effect, and the influence of the main steam temperature on the feed water is not considered, so that when the main steam temperature feedback and the set deviation are large, the operator needs to manually intervene the feed water flow. The embodiment of the present application sets the proportion gain and the integration gain of the second PID processing process according to the total load command, thereby improving the effect of PID adjustment. Further, the feed-forward bias is determined according to the main steam temperature and the flue gas recirculation, so that when the main steam temperature feedback and the set deviation are large, automatic adjustment is realized, without the need for the operator to manually intervene the feed water flow, thereby improving the timeliness and accuracy of the adjustment and reducing manual intervention.

[0097] Further, the coal quantity information includes a basic coal quantity and a coal quality correction coefficient.

[0098] The main steam pressure information includes a pressure set value and a main steam pressure.

[0099] The feed-forward feed water instruction is determined according to the basic feed water instruction, the coal quantity information, the limited amplitude and speed load instruction, the main steam pressure information, the boiler main control feed-forward and the fuel main control feed-forward, and includes:

[0100] The quotient obtained by sequentially dividing the basic feed water instruction by the basic coal quantity and the coal quality correction coefficient is multiplied by the boiler main control feed-forward to obtain a first feed-forward feed water instruction initial value;

[0101] The limited amplitude and speed load instruction is filtered by the fifth inertia filter to obtain a filtered limited amplitude and speed load instruction.

[0102] The difference obtained by subtracting the filtered limited amplitude and speed load instruction from the limited amplitude and speed load instruction is multiplied by a first proportion coefficient, and the product obtained is converted by the thirteenth conversion function to obtain a second feed-forward feed water instruction initial value.

[0103] The fuel main control feed-forward is multiplied by a second proportion coefficient, and the product obtained is filtered by the sixth inertia filter to obtain a third feed-forward feed water instruction initial value.

[0104] The pressure set value is subtracted from the main steam pressure to obtain a pressure difference value.

[0105] The pressure difference value is multiplied by a third proportion coefficient, and the product obtained is converted by the fourteenth conversion function to obtain a pressure difference value conversion value.

[0106] The pressure difference value is filtered by the sixth inertia filter to obtain a filtered pressure difference value.

[0107] The pressure difference value is subtracted from the filtered pressure difference value to obtain a pressure difference value differential value.

[0108] The pressure difference value conversion value is added to the pressure difference value differential value to obtain a fourth feed-forward feed water instruction initial value.

[0109] The initial value of the fifth feedforward water supply command is obtained by performing a bitwise AND operation on the initial values ​​of the first, second, third, and fourth feedforward water supply commands.

[0110] After the load command with limited amplitude and speed is converted into the initial value of the sixth feedforward water supply command through the fifteenth conversion function;

[0111] The feedforward water command is obtained by multiplying the initial values ​​of the fifth and sixth feedforward water commands.

[0112] In some embodiments, the inputs for determining the feedforward feedwater command logic include the basic feedwater command (obtained in step S100), basic coal quantity, coal quality correction coefficient, boiler main control feedforward, LDC (load command after limiting speed and amplitude), fuel main control feedforward, pressure setting, and main steam pressure. The feedforward feedwater command is formed by superimposing four feedforwards: boiler main control feedforward, fuel main control feedforward, main steam pressure, and unit load feedforward to the feedwater main control. The first feedforward is calculated from the basic feedwater command, basic coal quantity, coal quality correction coefficient, and boiler main control feedforward; the second feedforward is calculated from LDC; the third feedforward is calculated from fuel main control feedforward; and the fourth feedforward is calculated from pressure setting and main steam pressure. After superimposing the four feedforwards, multiplying them by a coefficient segmented according to LDC, the feedforward feedwater command is obtained.

[0113] The embodiments of the present invention have the following technical effects: based on the basic feedwater command, basic coal quantity, coal quality correction coefficient, boiler main control feedforward, load command after limiting speed, fuel main control feedforward, pressure setting, and main steam pressure determination, and with the addition of a feedforward feedwater command to the total feedwater command, the feedwater command can be adjusted in a timely manner during the load change phase of the unit, avoiding phenomena such as excessive deviation of main steam pressure.

[0114] On the other hand, such as Figure 2 As shown, this embodiment of the invention provides a water supply control device for deep peak shaving in a circulating fluidized bed unit, comprising:

[0115] The basic water supply instruction determination unit 200 is used to determine the basic water supply instruction based on the primary frequency regulation instruction, the load instruction after the amplitude and speed limit, the power generation load, the heating load and the actual water supply flow, and the first PID processing process.

[0116] Feedback water supply instruction determination unit 201 is used to determine the feedback water supply instruction based on the second PID processing process, according to the superheat-related information, the load instruction after the limit and speed limit, the total load instruction, the variable load information, the main air temperature feedback and setting information, and the flue gas recirculation information.

[0117] The feedforward water command determination unit 202 is used to determine the feedforward water command based on the basic feedforward command, coal quantity information, load command after limiting speed and amplitude, main steam pressure information, boiler main control feedforward and fuel main control feedforward.

[0118] The total water supply command determination unit 203 is used to sum the basic water supply command, the feedback water supply command and the feedforward water supply command to obtain the total water supply command;

[0119] The water supply control unit 204 is used to control the water supply of the circulating fluidized bed unit under deep peak shaving according to the total water supply command.

[0120] In some embodiments, such as Figure 3 As shown, in a specific embodiment, the total water supply command is obtained by superimposing the three parts of the embodiment of the present invention through the Keyuan NT6000 system algorithm function block. Specifically, the tenth summation module 10 is used to input the basic water supply command, the feedback water supply command, and the feedforward water supply command to the tenth summation module 10 to obtain the total water supply command.

[0121] Furthermore, the basic water supply instruction determination unit 200 includes:

[0122] The basic water supply flow determination module is used to determine the basic water supply flow based on the primary frequency regulation command and the load command after limiting amplitude and speed.

[0123] The water supply correction coefficient determination module is used to determine the current water supply correction coefficient based on the power generation load, heating load and actual water supply flow rate according to the first PID processing process.

[0124] The basic water supply instruction determination module is used to divide the basic water supply flow rate by the current water supply correction coefficient to obtain the basic water supply instruction.

[0125] Furthermore, the basic water supply flow rate determination module includes:

[0126] The base total load determination module determines the base total load based on the primary frequency regulation command and the load command after amplitude and speed limiting.

[0127] The first conversion module 41 is used to input the total basic load to the first conversion function to obtain the basic water supply flow rate.

[0128] In some embodiments, such as Figure 4As shown, in one specific embodiment, the embodiment of the present application can be realized by the algorithm function block of the Kexuan NT6000 system, and the basic total load is determined according to the primary frequency modulation instruction and the load instruction after amplitude limiting and speed limiting, specifically, the primary frequency modulation instruction is input to the eighth inertia filter module 28 (i.e. the LLAG module in the NT6000 system), wherein the time constant of the eighth inertia filter module 28 is 1.5 seconds, and the output quantity of the eighth inertia filter module 28 is connected to the seventh multiplication module 37 (i.e. the MUL module in the NT6000 system), and the product obtained by multiplying the output quantity of the eighth inertia filter module 28 by the fourth proportional coefficient MUL0.7 (wherein the fourth proportional coefficient is preferably 0.7) is input to the fifth summation module 15 (i.e. the ADD module in the NT6000 system) together with the load instruction after amplitude limiting and speed limiting (i.e. LDC), and the sum value obtained is taken as the basic total load; the basic total load is converted by the first conversion module 41 (which is a CHAR module in the NT6000 system, a piecewise broken line function module), and the basic feedwater flow is obtained. The first conversion function can be a piecewise function or other types of functions, which is used to convert the input basic total load into the basic feedwater flow.

[0129] Further, the feedwater correction coefficient determination module comprises:

[0130] The first summation module 11 is used for adding the power generation load and the heat supply load to obtain a power generation and heat supply load.

[0131] The second conversion module 42 is used for inputting the power generation and heat supply load to a second conversion function to obtain a predicted feedwater flow.

[0132] The first inertia filter module 21 is used for performing first inertia filtering on the actual feedwater flow to obtain an inertia-filtered feedwater flow.

[0133] The first multiplication module 31 is used for multiplying the inertia-filtered feedwater flow by a feedwater correction coefficient feedback value to obtain a corrected feedwater flow.

[0134] The first difference module 51 is used for subtracting the corrected feedwater flow from the predicted feedwater flow to obtain a feedwater flow difference.

[0135] The first comparison module 71 is used for judging whether the actual feedwater flow is less than a preset flow threshold value.

[0136] The first selection module 61 is used for setting the first PID flow difference to 0 if the actual feedwater flow is less than the preset flow threshold value, and otherwise taking the feedwater flow difference as the first PID flow difference.

[0137] The first PID processing module 81 is used to input the first PID flow difference as the set value of the first PID processing process to the first PID processing process to obtain the output control quantity of the first PID processing process.

[0138] The third conversion module 43 is used to input the output control quantity of the first PID processing process to the third conversion function, and use the output value of the third conversion function to update the current water supply correction coefficient.

[0139] The feedwater correction coefficient feedback value is the current feedwater correction coefficient obtained when performing the step of multiplying the feedwater flow rate after inertial filtering by the feedwater correction coefficient feedback value to obtain the corrected feedwater flow rate.

[0140] The first PID processing procedure includes: current sampled value, setpoint, proportional gain, integral gain, derivative gain, and output control quantity;

[0141] In some embodiments, such as Figure 4 As shown, in a specific embodiment, the present invention can be implemented through the algorithm function block of the Keyuan NT6000 system. The basic total load is determined according to the primary frequency regulation command and the load command after limiting the amplitude and speed. Specifically, the primary frequency regulation command is input to the eighth inertial filter module 28 (i.e., the LLAG module in the NT6000 system). The output of the eighth inertial filter module 28 is connected to the seventh multiplication module 37 (i.e., the MUL module in the NT6000 system). The seventh multiplication module 37 multiplies the output of the eighth inertial filter module 28 by the fourth proportional coefficient MUL0.7 (wherein, the fourth proportional coefficient is preferably 0.7). The product obtained is then input together with the load command after limiting the amplitude and speed (i.e., LDC) to the fifth summing module 15 (i.e., the ADD module in the NT6000 system). The sum obtained is used as the basic total load. The basic total load is converted into the basic water supply flow rate by the first conversion module 41 (which is the CHAR module in the NT6000 system, a piecewise linear function module). The first conversion function can be a piecewise function or other type of function, used to convert the input base total load into base water flow. The power generation load and heating load are input to the first summing module 11. The output of the first summing module 11 is connected to the second conversion module 42. The output of the second conversion module 42 is connected to the minuend input of the first difference module 51. The actual water flow is input to the first inertial filter module 21, where the time constant is 60 seconds. The output of the first inertial filter module 21 is connected to one multiplier input of the first multiplication module 31. The other multiplier input of the first multiplication module 31 is connected to the output of the third conversion module 43. The output of the first multiplication module 31 is connected to the subtrahend input of the first difference module 51. The output of the first difference module 51 is connected to the second input channel of the first selection module 61 (i.e.,...).Figure 4 the first selection module 61 (i.e. the Pv2 pin of the first selection module 61), the first input channel of the first selection module 61 (i.e. the Pv1 pin of the first selection module 61), the actual feedwater flow and the preset flow threshold value input to the first comparison module 71, preferably, the preset flow threshold value is 160 tons / hour, the first comparison module 71 compares whether the actual feedwater flow is less than the preset flow threshold value, the output result end of the first comparison module 71 is connected to the selection input end of the first selection module 61, and the output end of the first selection module 61 is connected to the current sampling value input end of the first PID processing module 81 (i.e. the SP pin of the first PID processing module 81). Figure 4 the first selection module 61 (i.e. the Pv2 pin of the first selection module 61), the first input channel of the first selection module 61 (i.e. the Pv1 pin of the first selection module 61), the actual feedwater flow and the preset flow threshold value input to the first comparison module 71, preferably, the preset flow threshold value is 160 tons / hour, the first comparison module 71 compares whether the actual feedwater flow is less than the preset flow threshold value, the output result end of the first comparison module 71 is connected to the selection input end of the first selection module 61, and the output end of the first selection module 61 is connected to the current sampling value input end of the first PID processing module 81 (i.e. the SP pin of the first PID processing module 81). Figure 4 the first selection module 61 (i.e. the Pv2 pin of the first selection module 61), the first input channel of the first selection module 61 (i.e. the Pv1 pin of the first selection module 61), the actual feedwater flow and the preset flow threshold value input to the first comparison module 71, preferably, the preset flow threshold value is 160 tons / hour, the first comparison module 71 compares whether the actual feedwater flow is less than the preset flow threshold value, the output result end of the first comparison module 71 is connected to the selection input end of the first selection module 61, and the output end of the first selection module 61 is connected to the current sampling value input end of the first PID processing module 81 (i.e. the SP pin of the first PID processing module 81). Figure 4 the first selection module 61 (i.e. the Pv2 pin of the first selection module 61), the first input channel of the first selection module 61 (i.e. the Pv1 pin of the first selection module 61), the actual feedwater flow and the preset flow threshold value input to the first comparison module 71, preferably, the preset flow threshold value is 160 tons / hour, the first comparison module 71 compares whether the actual feedwater flow is less than the preset flow threshold value, the output result end of the first comparison module 71 is connected to the selection input end of the first selection module 61, and the output end of the first selection module 61 is connected to the current sampling value input end of the first PID processing module 81 (i.e. the SP pin of the first PID processing module 81). Figure 4 the first selection module 61 (i.e. the Pv2 pin of the first selection module 61), the first input channel of the first selection module 61 (i.e. the Pv1 pin of the first selection module 61), the actual feedwater flow and the preset flow threshold value input to the first comparison module 71, preferably, the preset flow threshold value is 160 tons / hour, the first comparison module 71 compares whether the actual feedwater flow is less than the preset flow threshold value, the output result end of the first comparison module 71 is connected to the selection input end of the first selection module 61, and the output end of the first selection module 61 is connected to the current sampling value input end of the first PID processing module 81 (i.e. the SP pin of the first PID processing module 81). Figure 4 the first selection module 61 (i.e. the Pv2 pin of the first selection module 61), the first input channel of the first selection module 61 (i.e. the Pv1 pin of the first selection module 61), the actual feedwater flow and the preset flow threshold value input to the first comparison module 71, preferably, the preset flow threshold value is 160 tons / hour, the first comparison module 71 compares whether the actual feedwater flow is less than the preset flow threshold value, the output result end of the first comparison module 71 is connected to the selection input end of the first selection module 61, and the output end of the first selection module 61 is connected to the current sampling value input end of the first PID processing module 81 (i.e. the SP pin of the first PID processing module 81).

[0142] Further, the superheat related information includes superheat and superheat set bias;

[0143] The main steam temperature feedback and setting information includes: left main steam temperature feedback, left main steam temperature setting, right main steam temperature feedback, and right main steam temperature setting.

[0144] The flue gas recirculation information includes: flue gas recirculation air volume and flue gas recirculation input information.

[0145] The second PID processing process includes: current sampling value, set value, proportional gain, integral gain, differential gain, feedforward bias, and output control quantity.

[0146] The feedback feedwater instruction determination unit includes:

[0147] The second inertia filtering module 22 is configured to perform second inertia filtering on the limited-amplitude and limited-speed post-load instruction to obtain a second filtered limited-amplitude and limited-speed post-load instruction.

[0148] The fourth conversion module 44 is configured to convert the second filtered, limited-amplitude and limited-speed load instruction through a fourth conversion function to obtain a predicted superheat degree;

[0149] The second summation module 12 is configured to add the predicted superheat degree and the superheat degree setting bias to obtain a biased predicted superheat degree;

[0150] The fifth conversion module 45 is configured to convert the total load instruction through a fifth conversion function to obtain a first proportional parameter;

[0151] The sixth conversion module 46 is configured to convert the total load instruction through a sixth conversion function to obtain a second proportional parameter;

[0152] The seventh conversion module 47 is configured to convert the total load instruction through a seventh conversion function to obtain a first integral parameter;

[0153] The eighth conversion module 48 is configured to convert the total load instruction through an eighth conversion function to obtain a second integral parameter;

[0154] The second PID parameter selection module is configured to determine whether the variable load information is a variable load, and if the variable load information is a variable load, the first proportional parameter and the first integral parameter are taken as a PID proportional parameter and a PID integral parameter respectively, and if the variable load information is not a variable load, the second proportional parameter and the second integral parameter are taken as a PID proportional parameter and a PID integral parameter respectively;

[0155] The second difference module 52 is configured to subtract the left main steam temperature setting from the left main steam temperature feedback to obtain a left main steam temperature difference value;

[0156] The third difference module 53 is configured to subtract the right main steam temperature setting from the right main steam temperature feedback to obtain a right main steam temperature difference value;

[0157] The first maximum value acquisition module 2 is configured to compare the left main steam temperature difference value and the right main steam temperature difference value, and take the larger value as a main steam temperature difference value;

[0158] The ninth conversion module 49 is configured to convert the main steam temperature difference value through a ninth conversion function to obtain a first predicted superheat degree difference initial value;

[0159] The tenth conversion module 4A is configured to convert the main steam temperature difference value through a tenth conversion function to obtain a second predicted superheat degree difference initial value;

[0160] The second comparison module 72 is configured to determine whether the main steam temperature difference value is greater than zero;

[0161] The third selection module 63 is configured to: if the main steam temperature difference value is greater than zero, take the first predicted superheat difference initial value as a first predicted superheat difference value; otherwise, take the second predicted superheat difference initial value as the first predicted superheat difference value.

[0162] The third inertial filtering module 23 is configured to perform third inertial filtering on the flue gas recirculation air volume to obtain a filtered flue gas recirculation air volume.

[0163] The fourth inertial filtering module 24 is configured to perform fourth inertial filtering on the filtered flue gas recirculation air volume to obtain a twice-inertially-filtered flue gas recirculation air volume.

[0164] The fourth difference obtaining module 54 is configured to subtract the twice-inertially-filtered flue gas recirculation air volume from the filtered flue gas recirculation air volume to obtain a flue gas recirculation air volume difference value.

[0165] The eleventh conversion module 4B is configured to perform an eleventh conversion function on the flue gas recirculation air volume difference value to obtain a third predicted superheat difference initial value.

[0166] The twelfth conversion module 4C is configured to perform a twelfth conversion function on the filtered flue gas recirculation air volume to obtain a fourth predicted superheat difference initial value.

[0167] The third sum module 13 is configured to add the third predicted superheat difference initial value and the fourth predicted superheat difference initial value to obtain a fifth predicted superheat difference initial value.

[0168] The fourth selection module 64 is configured to determine whether flue gas recirculation input information is input flue gas recirculation; if the flue gas recirculation input information is input flue gas recirculation, take the fifth predicted superheat difference initial value as a second predicted superheat difference value; otherwise, take 0 as the second predicted superheat difference value.

[0169] The fifth difference obtaining module 55 is configured to subtract the second predicted superheat difference value from the first predicted superheat difference value to obtain a PID bias.

[0170] The second PID processing module 82 is configured to input the biased predicted superheat into the second PID processing process as a set value of the second PID processing process; input the superheat into the second PID processing process as a current sampling value of the second PID processing process; input a PID proportional parameter and a PID integral parameter into the second PID processing process as a proportional gain and an integral gain of the second PID processing process, respectively; input the PID bias into a feedforward bias of the second PID processing process; and take an output control quantity of the second PID processing process as a feedback water instruction.

[0171] In some embodiments, as Figure 5As shown, in one specific embodiment, the embodiment of the application can be realized by the algorithm function block of the Kexuan NT6000 system, the LDC (load command after amplitude limiting and speed limiting) is input to the second inertia filter module 22, wherein the time constant of the second inertia filter module 22 is 5 seconds, the second inertia filter module 22 is connected to the fourth conversion module 44, the output of the fourth conversion module 44 is connected to the input of the second summation module 12 together with the overheat degree setting bias; the total load command is input to the fifth conversion module 45, the sixth conversion module 46, the seventh conversion module 47 and the eighth conversion module 48; the second PID parameter selection module includes a proportional parameter selection module 621 and an integral parameter selection module 622, the outputs of the fifth conversion module 45 and the sixth conversion module 46 are connected to two input channels of the proportional parameter selection module 621, the outputs of the seventh conversion module 47 and the eighth conversion module 48 are connected to two input channels of the integral parameter selection module 622, the channel selection end of the proportional parameter selection module 621 and the integral parameter selection module 622 is connected to the variable load information; the left main steam temperature feedback and the left main steam temperature setting are input to the second difference module 52, the right main steam temperature feedback and the right main steam temperature setting are input to the third difference module 53, the outputs of the second difference module 52 and the third difference module 53 are connected to the input of the first maximum value acquisition module 2, the first maximum value acquisition module 2 is used to select the maximum value in the input, the output of the first maximum value acquisition module 2 is connected to the ninth conversion module 49, the tenth conversion module 4A and the second comparison module 72, the outputs of the ninth conversion module 49 and the tenth conversion module 4A are connected to two input channels of the third selection module 63, the other comparison input of the second comparison module 72 is set to 0, the output of the second comparison module 72 is connected to the channel selection end of the third selection module 63, the second comparison module 72 is used to judge whether the output value of the first maximum value acquisition module 2 is greater than zero.The flue gas recirculation air volume input is input to the third inertial filter module 23, the output of the third inertial filter module 23 is connected to the input of the fourth inertial filter module 24, the fourth difference module 54 and the twelfth conversion module 4C, wherein the time constant of the fourth inertial filter module 24 is 240 seconds, the output of the fourth difference module 54 is connected to the eleventh conversion module 4B, the outputs of the eleventh conversion module 4B and the twelfth conversion module 4C are connected to the input of the third summation module 13, the output of the third summation module 13 is connected to the input channel of the fourth selection module 64, another input channel of the fourth selection module 64 inputs a value of 0, the flue gas recirculation input information is connected to the channel selection end of the fourth selection module 64, the outputs of the fourth selection module 64 and the third selection module 63 are connected to the input of the fifth difference module 55, the output of the fifth difference module 55 is connected to the current sampling value input end of the superheat degree, the output of the second summation module 12 is connected to the set value input end of the second PID processing module 82, the output of the proportional parameter selection module 621 is connected to the proportional gain input end of the second PID processing module 82, the output of the integral parameter selection module 622 is connected to the integral gain input end of the second PID processing module 82, the differential gain input end of the second PID processing module 82 is a value of 0, and the output of the fifth difference module 55 is connected to the feedforward bias input end of the second PID processing module 82. The differential gain of the second PID processing module 82 (the Td pin of the second PID processing module 82 in the formula) is set to 0; the upper limit of the output of the second PID processing module 82 (the HLOP pin of the second PID processing module 82 in the formula) is set to 150, and the lower limit of the output of the second PID processing module 82 (the LLOP pin of the second PID processing module 82 in the formula) is set to -150. Figure 5 Figure 5 Figure 5

[0172] Further, the coal quantity information includes a basic coal quantity and a coal quality correction coefficient;

[0173] The main steam pressure information includes a pressure set value and a main steam pressure;

[0174] The feedforward feedwater instruction determination unit includes:

[0175] The first feedforward feedwater instruction initial value determination module is configured to divide the basic feedwater instruction by the basic coal quantity and the coal quality correction coefficient in sequence to obtain a quotient, and multiply the quotient by a boiler main control feedforward to obtain a first feedforward feedwater instruction initial value; in some embodiments, as Figure 6 ​​​As shown in the figure, in one embodiment, the embodiment of the application can be realized by the algorithm function block of the Kedao NT6000 system. The basic water supply instruction and the basic coal quantity input are input to the second division module 92, the output of the second division module 92 and the coal quality correction coefficient are input to the third division module 93, the output of the third division module 93 and the boiler master control feedforward are input to the second multiplication module 32, and the output of the second multiplication module 32 is used as the first feedforward water supply instruction initial value; the fifth inertia filter module 25 is used for filtering the amplitude-limited and speed-limited post-load instruction to obtain a filtered amplitude-limited and speed-limited post-load instruction; the second feedforward water supply instruction initial value determination module is used for multiplying the difference obtained by subtracting the filtered amplitude-limited and speed-limited post-load instruction from the amplitude-limited and speed-limited post-load instruction by a first proportional coefficient, and then converting the obtained product by the thirteenth conversion function to obtain the second feedforward water supply instruction initial value;

[0176] As shown in the figure, Figure 6 The second feedforward water supply instruction initial value determination module includes a sixth difference module 56, a third multiplication module 33 and a thirteenth conversion module 4D. The amplitude-limited and speed-limited post-load instruction is input to the fifth inertia filter module 25, wherein the time constant of the fifth inertia filter module 25 is 90 seconds. The amplitude-limited and speed-limited post-load instruction and the output of the fifth inertia filter module 25 are both input to the sixth difference module 56. The output of the sixth difference module 56 is connected to one input of the third multiplication module 33. The other input of the third multiplication module 33 is MUL3 (i.e. the first proportional coefficient, preferably a value of 3). The output of the third multiplication module 33 is connected to the thirteenth conversion module 4D. The output of the thirteenth conversion module 4D is used as the second feedforward water supply instruction initial value.

[0177] The third feedforward water supply instruction initial value determination module is used for multiplying the fuel master control feedforward by a second proportional coefficient, and obtaining the third feedforward water supply instruction initial value after filtering the obtained product by the sixth inertia filter.

[0178] As shown in the figure, Figure 6 The third feedforward water supply instruction initial value determination module includes a fourth multiplication module 34 and a sixth inertia filter module 26. The time constant of the sixth inertia filter module 26 is 140 seconds. The fuel master control feedforward and the second proportional coefficient are input to the fourth multiplication module 34, wherein the second proportional coefficient MUL3.2 is preferably 3.2. The output of the fourth multiplication module 34 is connected to the input of the sixth inertia filter module 26. The output of the sixth inertia filter module 26 is used as the third feedforward water supply instruction initial value.

[0179] The fourth feed-forward feedwater command initial value determination module is configured to subtract the main steam pressure from the pressure set value to obtain a pressure difference value; multiply the pressure difference value by a third proportional coefficient to obtain a product; convert the product by a fourteenth conversion function to obtain a pressure difference value conversion value; filter the pressure difference value by a sixth inertia filter to obtain a filtered pressure difference value; subtract the filtered pressure difference value from the pressure difference value to obtain a pressure difference value differential; and add the pressure difference value conversion value and the pressure difference value differential to obtain the fourth feed-forward feedwater command initial value.

[0180] As shown in Figure 6 The fourth feed-forward feedwater command initial value determination module includes a seventh difference module 57, a fifth multiplication module 35, a fourteenth conversion module 4E, a seventh inertia filter module 27, an eighth difference module 58, a fifteenth conversion module 4F, a fourth summation module 14, and a sixth multiplication module. The time constant of the seventh inertia filter module 27 is 90 seconds. The third proportional coefficient MUL1.1 is preferably 1.1. The pressure set value and the main steam pressure are input to the seventh difference module 57. The output of the seventh difference module 57 is connected to one input of the fifth multiplication module 35. The other input of the fifth multiplication module 35 is connected to the third proportional coefficient. The output of the fifth multiplication module 35 is connected to the fourteenth conversion module 4E. The output of the fourteenth conversion module 4E is connected to one input of the fourth summation module 14. The output of the seventh difference module 57 is also connected to the input of the seventh inertia filter module 27 and one minuend input terminal of the eighth difference module 58. The output terminal of the seventh inertia filter module 27 is connected to the minuend input terminal of the eighth difference module 58. The output of the eighth difference module 58 is connected to the other input terminal of the fourth summation module 14. The output of the fourth summation module 14 is the fourth feed-forward feedwater command initial value.

[0181] The fifth feed-forward feedwater command initial value determination module is configured to perform a sum operation on the first feed-forward feedwater command initial value, the second feed-forward feedwater command initial value, the third feed-forward feedwater command initial value, and the fourth feed-forward feedwater command initial value to obtain the fifth feed-forward feedwater command initial value.

[0182] As shown in Figure 6 The fifth feed-forward feedwater command initial value determination module includes a first sum module 1 configured to perform a sum operation on the first feed-forward feedwater command initial value, the second feed-forward feedwater command initial value, the third feed-forward feedwater command initial value, and the fourth feed-forward feedwater command initial value to obtain the fifth feed-forward feedwater command initial value

[0183] The sixth feed-forward feedwater command initial value determination module is configured to convert the limited-amplitude and limited-speed load command by a fifteenth conversion function to obtain the sixth feed-forward feedwater command initial value.

[0184] As shown in Figure 6As shown in the embodiment of the present application, the sixth feedforward feedwater command initial value determination module comprises a fifteenth conversion module 4F, the amplitude-limited and speed-limited load command is input to the fifteenth conversion module 4F, and the output of the fifteenth conversion module 4F is taken as the sixth feedforward feedwater command initial value.

[0185] The feedforward feedwater command determination module is configured to multiply the fifth feedforward feedwater command initial value and the sixth feedforward feedwater command initial value to obtain the feedforward feedwater command.

[0186] As shown in the embodiment of the present application, the feedforward feedwater command determination module comprises a sixth multiplication module 36, the fifth feedforward feedwater command initial value and the sixth feedforward feedwater command initial value are input to the sixth multiplication module 36, and the feedforward feedwater command is obtained after multiplication. Figure 6

[0187] In the above embodiment, when the embodiment is implemented using the Kexuan NT6000 system, the first multiplication module 31, the second multiplication module 32, the third multiplication module 33, the fourth multiplication module 34, the fifth multiplication module 35, the sixth multiplication module 36, and the seventh multiplication module 37 are all implemented using the MUL module in the Kexuan NT6000 system;

[0188] The first conversion module 41, the second conversion module 42, the third conversion module 43, the fourth conversion module 44, the fifth conversion module 45, the sixth conversion module 46, the seventh conversion module 47, the eighth conversion module 48, the ninth conversion module 49, the tenth conversion module 4A, the eleventh conversion module 4B, the twelfth conversion module 4C, the thirteenth conversion module 4D, the fourteenth conversion module 4E, and the fifteenth conversion module 4F are all implemented using the lead-lag module (CHAR) in the Kexuan NT6000 system;

[0189] The first summation module 11, the second summation module 12, the third summation module 13, the fourth summation module 14, the fifth summation module 15, and the tenth summation module 10 are all implemented using the summation module (ADD) in the Kexuan NT6000 system;

[0190] The first inertia filter module 21, the second inertia filter module 22, the third inertia filter module 23, the fourth inertia filter module 24, the fifth inertia filter module 25, the sixth inertia filter module 26, the seventh inertia filter module 27, and the eighth inertia filter module 28 are all implemented using the lead-lag module (LLAG) in the Kexuan NT6000 system;

[0191] ​The first difference module 51, the second difference module 52, the third difference module 53, the fourth difference module 54, the fifth difference module 55, the sixth difference module 56, the seventh difference module 57 and the eighth difference module 58 all use the lead-lag module (LLAG) in the Kexuan NT6000 system; the first selection module 61, the proportional parameter selection module 621, the gain parameter selection module 622, the third selection module 63 and the fourth selection module 64 all use the selection module (SWCH) in the Kexuan NT6000 system;

[0192] The first comparison module 71 and the second comparison module 72 both use the comparison module (CMP) in the Kexuan NT6000 system;

[0193] The first PID processing module 81 and the second PID processing module 82 both use the PID controller module (PID) in the Kexuan NT6000 system;

[0194] The first division module 91, the second division module 92 and the third division module 93 all use the division module (DIV) in the Kexuan NT6000 system;

[0195] The first AND module 1 uses the AND module (AND) in the Kexuan NT6000 system;

[0196] The first maximum value acquisition module 2 uses the maximum value module (MAX) in the Kexuan NT6000 system.

[0197] The above technical solutions of the embodiments of the present application will be described in detail below in combination with specific application examples, and technical details not introduced in the implementation process can refer to the related descriptions in the foregoing.

[0198] The embodiments of the present application take the algorithm function blocks of the Kexuan NT6000 system as an example to provide a feedwater control scheme for deep peak shaving of a circulating fluidized bed unit. The scheme includes a lead-lag module (LLAG), a limiting module (LIM), a selection module (SWCH), a PID controller module (PID), a comparison module (CMP), an intelligent tracking module (TRAK) and the like. The final feedwater instruction is obtained by adding three parts: the first part is a basic feedwater instruction generated by a load instruction; the second part is a feedback feedwater instruction corrected by superheat; and the third part is a feedforward of a boiler master control, a fuel master control feedforward amount, a main steam pressure and a unit load to a feedwater master control, and four-way feedforward superposition forms a feedforward feedwater instruction. The control scheme can ensure that the feedwater flow changes in time during the variable load stage of the unit, and at the same time, the coal quality change, the intermediate point temperature fluctuation, the flue gas recirculation input and the like are taken into account, and at the same time, the feedwater flow can be kept stable during the deep peak shaving stage of the unit.

[0199] The specific implementation is as follows:

[0200] A feedwater control system for deep peak shaving of a circulating fluidized bed unit, characterized in that it comprises a lead-lag module (LLAG), a limiting module (LIM), a selection module (SWCH), a PID controller module (PID), a comparison module (CMP), an intelligent tracking module (TRAK), an addition module (ADD), a multiplication module (MUL), a piecewise function module (CHAR), an OR gate (OR), a NOT gate (NOT) and a time delay module (TD).

[0201] A feedwater control method for deep peak shaving of a circulating fluidized bed unit, comprising three parts of logic. The first part is the basic feedwater instruction generated by the load instruction. Compared with the traditional scheme, the calculation logic of the feedwater BTU coefficient is added, and the basic feedwater flow obtained by the load instruction is divided by the feedwater BTU coefficient to obtain the basic feedwater instruction. Moreover, in consideration of the deep peak shaving situation, the logic of stopping the calculation of the feedwater BTU coefficient when the feedwater flow is less than 160 t / h is added to avoid triggering the minimum protection of the feedwater flow. The second part is to send the deviation of the superheat degree and the set value into the PID controller to obtain the feedback feedwater instruction of the superheat degree correction, and at the same time, the influence of the left and right side main steam temperatures and the flue gas recirculation air volume is considered to superimpose the corresponding feedforward. The third part is to calculate the boiler master control output, LDC, fuel master control feedforward and main steam pressure to feedwater master control respectively, and the four-way feedforward is superimposed to form the feedforward feedwater instruction.

[0202] In the first part of the logic, the basic feedwater instruction is calculated. The input points of the logic include the primary frequency modulation instruction, LDC, power generation load, heating load and feedwater flow. The logic contains two parts: first, a total load is calculated from the primary frequency modulation instruction and LDC, and after the piecewise function, the corresponding feedwater flow is converted; then the feedwater BTU coefficient is calculated from the power generation load, heating load and feedwater flow, and the coefficient ranges from 0.85 to 1.15. The feedwater flow converted by the first part is divided by the feedwater BTU coefficient to obtain the basic feedwater instruction.

[0203] In the second part of the logic, the feedback feedwater instruction is calculated. The input points of the logic include the superheat degree, LDC, MT_BIAS, total load instruction, variable load, left side steam temperature feedback, left side steam temperature set value, right side steam temperature feedback, right side steam temperature set value, flue gas recirculation air volume and flue gas recirculation input. The logic contains two parts: first, the feedback feedwater instruction is calculated by the PID module from the set value and feedback value of the superheat degree. At the same time, the proportion (Xp pin) and integration (Ti pin) of the PID module are not set as constants, but are distinguished in the state of whether the unit is variable load, and in the variable load state, the total load instruction is also processed by segmented variable parameters; the second part is the calculation of the feedforward amount (Ff pin) MT_FF of the PID module. This part considers the influence of the main steam temperature and the flue gas recirculation, and the main steam temperature takes the larger one of the feedback and set value deviation of the left and right sides to calculate.

[0204] In the third part of logic, the feedforward feedwater instruction is calculated. The input points of the logic include the basic feedwater instruction (calculated by the first part of logic), the basic coal quantity, the coal quality correction coefficient, the boiler master control feedforward, the LDC, the fuel master control feedforward, the pressure setting, and the main steam pressure. The feedforward feedwater instruction is formed by superposition of four feedforwards, i.e. the boiler master control feedforward, the fuel master control feedforward, the main steam pressure, and the feedforward of the unit load to the feedwater master control. The first feedforward is calculated by the basic feedwater instruction (calculated by the first part of logic), the basic coal quantity, the coal quality correction coefficient, and the boiler master control feedforward; the second feedforward is calculated by the LDC; the third feedforward is calculated by the fuel master control feedforward; and the fourth feedforward is calculated by the pressure setting and the main steam pressure. After superposition of the four feedforwards, a coefficient segmented according to the LDC is multiplied, and the feedforward feedwater instruction is obtained.

[0205] The following continues to be described by another embodiment:

[0206] The inventor finds that the basic principle of the existing circulating fluidized bed unit feedwater control scheme is to add the feedback feedwater instruction to the basic feedwater instruction. This method has three main shortcomings:

[0207] The first is that the basic feedwater instruction is only calculated by the LDC. In the existing scheme, the basic feedwater instruction is only calculated by the LDC, and the feedwater BTU coefficient is not considered because the LDC is only the set value of the power generation load, which will lead to the situation that the feedwater flow calculated by the LDC is not accurate in the heating condition.

[0208] The second is that in the calculation logic of the feedback feedwater instruction, the proportion and integral of the PID module are fixed values, which do not change with the total load instruction, leading to poor adjustment effect; and the influence of the main steam temperature on the feedwater is not considered, so that when the main steam temperature feedback and setting deviation is large, the operator needs to manually intervene the feedwater flow.

[0209] The third is the lack of feedforward feedwater instruction, so that the feedwater instruction cannot follow the adjustment in time in the variable load stage, leading to the phenomenon that the main steam pressure deviation is large.

[0210] To solve the above problems, the embodiment of the application provides a circulating fluidized bed unit deep peak shaving feedwater control method and device, which overcomes the shortcomings of the original control scheme, and increases the feedwater BTU coefficient calculation in the basic feedwater instruction, the proportion and integral of the PID module in the feedback feedwater instruction, the influence of the main steam temperature on the feedback feedwater instruction, and the feedforward feedwater instruction.

[0211] To achieve the above object, on the one hand, embodiments of the present application take a 350 MW circulating fluidized bed unit as an example, and provide a feedwater control method for deep peak shaving of a circulating fluidized bed unit, comprising the following steps:

[0212] In the basic feedwater instruction logic, the primary frequency modulation instruction is passed through a 1.5s inertia module, multiplied by 0.7, added to the LDC, converted into a corresponding feedwater flow through a broken line function module, and divided by the feedwater BTU coefficient, so as to obtain the basic feedwater instruction.

[0213] In the basic feedwater instruction logic, the calculation logic of the feedwater BTU coefficient is as follows: the power generation load plus the heat supply load is passed through a broken line function module, then the feedwater flow is subtracted through a 60s inertia module, the obtained quantity is multiplied by the feedwater BTU coefficient, and the difference is sent to the selection module Pv2 pin, and the Pv1 pin value is 0. When the feedwater flow is lower than 160t / h, the selection module output is Pv1, otherwise it is Pv2, and then the output is connected with the SP pin of the PID module, the PV value of the PID module is 0, the proportion is 0, and the integral is 3600. The output of the PID is passed through a broken line function module, and the output is the feedwater BTU coefficient.

[0214] In the feedback feedwater instruction logic, the superheat degree is connected with the PV pin of the PID; the LDC is passed through a 5s inertia module, then passed through a broken line function module, the output is superimposed with the MT_BIAS, and then connected with the SP pin of the PID; the MT_FF (i.e. the PID bias) is connected with the Ff (i.e. the feedforward bias) pin of the PID module; in the case that the variable load value is TRUE and FALSE, the Xp and Ti of the PID module correspond to different values, which are calculated by the load total instruction passing through a broken line function module, i.e. the proportional and integral actions are processed in sections under variable load; the Td pin is 0; the high and low limits HLOP and LLOP of the PID output are 150 and -150 respectively.

[0215] In the feedback feedwater instruction logic, the calculation method of the MT_FF is as follows: the left and right side steam temperature feedbacks are subtracted from the settings, the larger of the two side deviations is taken, and then sent to two different broken line modules, the outputs are connected with the Pv1 pin and the Pv2 pin of the selection module respectively, and the selection conditions are whether the deviation is greater than 0; the selection condition of the second selection module is whether the flue gas recirculation is put into, and the Pv2 pin input is 0. The flue gas recirculation air volume is divided into three routes after passing through an inertia module, the first route is subtracted from the second route after passing through a 240s inertia, then the broken line function module is passed through, superimposed with the third route passing through a broken line function module, and sent to the Pv1 pin; the outputs of the two selection modules are subtracted, i.e. the MT_FF is obtained.

[0216] In the feedforward feedwater instruction logic, there are four feedforward paths. The first feedforward path is the basic feedwater instruction divided by the basic coal amount, divided by the coal quality correction coefficient, multiplied by the boiler master control feedforward. The second feedforward path is the LDC itself minus the LDC through a 90s inertia module, multiplied by a coefficient of 3, and then through a broken line function module. The third feedforward path is the fuel master control feedforward multiplied by a coefficient of 3.2, and then through a 140s inertia module. The fourth feedforward path is the pressure set minus the main steam pressure, and then divided into three paths. The first path is multiplied by a coefficient of 1.1, and then connected to a broken line function module. The second path is subtracted from the output of the third path through a 90s inertia module, and the result is added to the first path. After the four feedforward paths are added together, the result is multiplied by a coefficient obtained from the LDC through a broken line function module, and the result is the feedforward feedwater instruction.

[0217] The basic feedwater instruction, the feedback feedwater instruction, and the feedforward feedwater instruction are added together, and the result is the total feedwater instruction.

[0218] It should be understood that the particular order or hierarchy of steps in processes disclosed is an example that can be re-arranged as desired. The particular order or hierarchy of steps in processes disclosed should not be interpreted as reflecting an intention that the steps of the processes are intended to be performed in the order recited or that they are intended to be performed at the particular time recited or in the described order, but are instead intended to be performed, or carried out, in any order, including sequentially or simultaneously. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

[0219] In the above detailed description, various features are grouped together in single embodiments for the purpose of streamlining the disclosure. This disclosed approach is not to be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are explicitly recited in each claim. Rather, as the claims below reflect, inventive subject matter lies in fewer than all features of the disclosed single embodiments. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate preferred embodiment of the inventive subject matter.

[0220] The disclosed embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein. The scope of the disclosure is therefore indicated by the following claims, rather than by the foregoing description. In this respect, reference is made to the appended claims and not to the foregoing description as indicating the scope of the disclosure.

[0221] The above description includes examples of one or more embodiments. Of course, not all possible combinations of components or methods described above will be employed to make or use the embodiments nor will all of

[0222] The above description is further explained with reference to the accompanying drawings in which the specific embodiments are shown. It is understood that the detailed description and specific examples that follow are intended to explain the embodiments of the application and are not intended to limit the scope of the application. It is understood that the examples given are intended to explain the present application and are not intended to limit the present application. It is understood that the examples given are intended to explain the present application and are not intended to limit the present application.

Claims

1. A feedwater control method for deep peaking of a circulating fluidized bed unit, characterized by, The method comprises the following steps: determining a basic feedwater command based on a first PID processing procedure according to a primary frequency modulation command, a post-amplitude-limiting and speed-limiting load command, a power generation load, a heat supply load, and an actual feedwater flow rate; determining a feedback feedwater command based on a second PID processing procedure according to superheat degree related information, the post-amplitude-limiting and speed-limiting load command, a total load command, variable load information, main steam temperature feedback and setting information, and flue gas recirculation information; determining a feedforward feedwater command according to the basic feedwater command, coal quantity information, the post-amplitude-limiting and speed-limiting load command, main steam pressure information, boiler main control feedforward, and fuel main control feedforward; summing the basic feedwater command, the feedback feedwater command, and the feedforward feedwater command to obtain a total feedwater command; controlling the feedwater of a circulating fluidized bed unit under deep peak shaving according to the total feedwater command; The method of determining a basic feedwater command based on a first PID processing procedure according to a primary frequency modulation command, a post-amplitude-limiting and speed-limiting load command, a power generation load, a heat supply load, and an actual feedwater flow rate comprises the following steps: determining a basic feedwater flow rate according to a primary frequency modulation command and a post-amplitude-limiting and speed-limiting load command; determining a current feedwater correction coefficient based on a first PID processing procedure according to a power generation load, a heat supply load, and an actual feedwater flow rate; dividing the basic feedwater flow rate by the current feedwater correction coefficient to obtain the basic feedwater command; The method of determining a current feedwater correction coefficient based on a first PID processing procedure according to a power generation load, a heat supply load, and an actual feedwater flow rate comprises the following steps: adding the power generation load and the heat supply load to obtain a power generation and heat supply load; inputting the power generation and heat supply load into a second conversion function to obtain a predicted feedwater flow rate; subjecting an actual feedwater flow rate to first inertia filtering to obtain an inertia-filtered feedwater flow rate; multiplying the inertia-filtered feedwater flow rate by a feedwater correction coefficient feedback value to obtain a corrected feedwater flow rate; subtracting the corrected feedwater flow rate from the predicted feedwater flow rate to obtain a feedwater flow rate difference; determining whether the actual feedwater flow rate is less than a preset flow rate threshold value; if the actual feedwater flow rate is less than the preset flow rate threshold value, setting a first PID flow rate difference to 0, otherwise, using the feedwater flow rate difference as the first PID flow rate difference; inputting the first PID flow rate difference as a set value of the first PID processing procedure into the first PID processing procedure, inputting an output control quantity of the first PID processing procedure into a third conversion function, and updating the current feedwater correction coefficient using an output value of the third conversion function; wherein the feedwater correction coefficient feedback value is a current feedwater correction coefficient obtained when the step of multiplying the inertia-filtered feedwater flow rate by the feedwater correction coefficient feedback value to obtain the corrected feedwater flow rate is performed; wherein parameters of the first PID processing procedure include a current sampling value, a set value, a proportional gain, an integral gain, a differential gain, and an output control quantity; the superheat degree related information includes superheat degree and superheat degree setting bias; the main steam temperature feedback and setting information includes left side main steam temperature feedback, left side main steam temperature setting, right side main steam temperature feedback, and right side main steam temperature setting; the flue gas recirculation information includes flue gas recirculation air volume and flue gas recirculation input information; The parameters of the second PID processing process include: a current sampling value, a set value, a proportional gain, an integral gain, a differential gain, a feedforward bias, and an output control quantity; The determination of the feedback water command according to the superheat degree related information, the limited-amplitude and limited-speed post-load command, the total load command, the variable load information, the main steam temperature feedback and setting information, and the flue gas recirculation information comprises: The limited-amplitude and limited-speed post-load command is filtered by a second inertia filter to obtain a second filtered limited-amplitude and limited-speed post-load command; The second filtered limited-amplitude and limited-speed post-load command is converted by a fourth conversion function to obtain a predicted superheat degree; The predicted superheat degree is added to the superheat degree set bias to obtain a biased predicted superheat degree; The biased predicted superheat degree is input to the second PID processing process as a set value of the second PID processing process; The superheat degree is input to the second PID processing process as a current sampling value of the second PID processing process; The total load command is converted by a fifth conversion function to obtain a first proportional parameter; The total load command is converted by a sixth conversion function to obtain a second proportional parameter; The total load command is converted by a seventh conversion function to obtain a first integral parameter; The total load command is converted by an eighth conversion function to obtain a second integral parameter; It is determined whether it is a variable load according to the variable load information; If the variable load information is a variable load, the first proportional parameter and the first integral parameter are respectively taken as a PID proportional parameter and a PID integral parameter; If the variable load information is not a variable load, the second proportional parameter and the second integral parameter are respectively taken as a PID proportional parameter and a PID integral parameter; The PID proportional parameter and the PID integral parameter are respectively input to the second PID processing process as a proportional gain and an integral gain of the second PID processing process; The left main steam temperature feedback is subtracted from the left main steam temperature setting to obtain a left main steam temperature difference value; The right main steam temperature feedback is subtracted from the right main steam temperature setting to obtain a right main steam temperature difference value; The left main steam temperature difference value and the right main steam temperature difference value are compared, and the larger value is taken as a main steam temperature difference value; The main steam temperature difference value is converted by a ninth conversion function to obtain a first predicted superheat degree difference initial value; The main steam temperature difference value is converted by a tenth conversion function to obtain a second predicted superheat degree difference initial value; It is determined whether the main steam temperature difference value is greater than zero; If the main steam temperature difference value is greater than zero, the first predicted superheat degree difference initial value is taken as a first predicted superheat degree difference value, otherwise the second predicted superheat degree difference initial value is taken as a first predicted superheat degree difference value; The flue gas recirculation air volume is filtered by a third inertia filter to obtain a filtered flue gas recirculation air volume; The filtered flue gas recirculation air volume is filtered by a fourth inertia filter to obtain a twice inertia filtered flue gas recirculation air volume; The difference between the filtered flue gas recirculation air volume and the twice inertia filtered flue gas recirculation air volume is converted by an eleventh conversion function to obtain a third predicted superheat degree difference initial value; The filtered flue gas recirculation air volume is converted by a twelfth conversion function to obtain a fourth predicted superheat degree difference initial value; The third predicted superheat degree difference initial value and the fourth predicted superheat degree difference initial value are added to obtain a fifth predicted superheat degree difference initial value; judging whether the flue gas recirculation input information is inputting flue gas recirculation; if the flue gas recirculation input information is inputting flue gas recirculation, taking the fifth predicted superheat difference initial value as a second predicted superheat difference value; otherwise, taking 0 as the second predicted superheat difference value; subtracting the second predicted superheat difference value from the first predicted superheat difference value to obtain a PID bias; inputting the PID bias to a feedforward bias of a second PID processing process; taking an output control quantity of the second PID processing process as a feedback water instruction.

2. The feedwater control method for deep peaking of a circulating fluidized bed unit as set forth in claim 1, characterized by, the determining of the basic feedwater flow according to the primary frequency modulation instruction and the limited-amplitude and limited-speed post-load instruction comprises: determining a basic total load according to the primary frequency modulation instruction and the limited-amplitude and limited-speed post-load instruction; inputting the basic total load to a first conversion function to convert to obtain the basic feedwater flow.

3. The feedwater control method for deep peaking of a circulating fluidized bed unit as set forth in claim 1, characterized by, the coal quantity information comprises a basic coal quantity and a coal quality correction coefficient; the main steam pressure information comprises a pressure set value and a main steam pressure; the determining of the feedforward feedwater instruction according to the basic feedwater instruction, the coal quantity information, the limited-amplitude and limited-speed post-load instruction, the main steam pressure information, a boiler master feedforward and a fuel master feedforward comprises: dividing the basic feedwater instruction by the basic coal quantity and the coal quality correction coefficient in sequence to obtain a quotient, and multiplying the quotient by the boiler master feedforward to obtain a first feedforward feedwater instruction initial value; the limited-amplitude and limited-speed post-load instruction is filtered by a fifth inertia filter to obtain a filtered limited-amplitude and limited-speed post-load instruction; multiplying a difference between the limited-amplitude and limited-speed post-load instruction and the filtered limited-amplitude and limited-speed post-load instruction by a first proportional coefficient, and converting a product obtained by the multiplication by a thirteenth conversion function to obtain a second feedforward feedwater instruction initial value; multiplying the fuel master feedforward by a second proportional coefficient, and filtering a product obtained by the multiplication by a sixth inertia filter to obtain a third feedforward feedwater instruction initial value; subtracting the main steam pressure from the pressure set value to obtain a pressure difference value; multiplying the pressure difference value by a third proportional coefficient, and converting a product obtained by the multiplication by a fourteenth conversion function to obtain a pressure difference value conversion value; filtering the pressure difference value by the sixth inertia filter to obtain a filtered pressure difference value; subtracting the filtered pressure difference value from the pressure difference value to obtain a pressure difference value differential value; adding the pressure difference value conversion value and the pressure difference value differential value to obtain a fourth feedforward feedwater instruction initial value; performing an AND operation on the first feedforward feedwater instruction initial value, the second feedforward feedwater instruction initial value, the third feedforward feedwater instruction initial value and the fourth feedforward feedwater instruction initial value to obtain a fifth feedforward feedwater instruction initial value; converting the limited-amplitude and limited-speed post-load instruction by a fifteenth conversion function to obtain a sixth feedforward feedwater instruction initial value; multiplying the fifth feedforward feedwater instruction initial value and the sixth feedforward feedwater instruction initial value to obtain the feedforward feedwater instruction.

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