Frequency modulation method and system by using instantaneous spray water flow of desuperheating water of coal-fired unit boiler

Abstract

The invention relates to the technical field of coal-fired unit desuperheating water spraying, in particular to a method and system for frequency modulation through coal-fired unit boiler desuperheating water instantaneous water spraying flow. The frequency modulation method using the instantaneous spray water flow of the desuperheating water of the coal-fired unit boiler comprises the following steps: firstly, determining increase or decrease of a unit load corresponding to a primary frequency modulation instruction in a DCS (Distributed Control System) corresponding to the coal-fired unit boiler; secondly, primary boiler desuperheating water instantaneous control logic is added in primary frequency modulation instruction response control logic configuration in the DCS control system, so that the primary boiler desuperheating water instantaneous control logic is controlled according to increase or decrease of unit load; and finally, applying the boiler desuperheating water instantaneous control logic to the opening degree of a desuperheating water control valve in a DCS (Distributed Control System) so as to realize desuperheating water instantaneous water spraying flow control. The method can achieve the quick change of the unit load, and can better respond to the primary frequency modulation signal of the unit.

Description

Technical Field

[0001] The invention relates to the technical field of water spraying for cooling water of coal-fired units, and in particular to a method and system for frequency modulation of instantaneous water spraying flow rate of cooling water of a boiler of a coal-fired unit. Background Art

[0002] When a coal-fired boiler performs a frequency modulation operation, it will show significant hysteresis due to its huge thermal inertia and complex thermal system. Specifically, starting from receiving the frequency modulation signal of the power grid, the coal-fired boiler needs a certain amount of time to respond to this change. First, the fuel input and air supply are adjusted to change the combustion intensity, which in turn affects the heat energy generation in the boiler; then, the heat energy accumulates in the boiler and is gradually transferred to the superheater and reheater, causing the steam parameters to change; finally, these changes are transmitted to the steam turbine through the steam pipe, affecting its steam intake and power output. Throughout the process, the combustion, heat release, steam generation and temperature regulation of the boiler all involve the accumulation and release of heat, resulting in a time delay between the issuance of the frequency modulation command and the actual change of the unit output. This lag may affect the timeliness and accuracy of the power grid frequency modulation.

[0003] The existing technical means are mainly aimed at optimizing and adjusting the combustion, boiler air volume and coal volume, but they cannot solve the above-mentioned lag very well. The specific process of the traditional primary frequency regulation action is: after the primary frequency regulation command of the power grid is issued, the steam turbine throttle will act first to control the flow into the steam turbine and adjust the unit load. At the same time, the boiler coordinated control system receives the load command and starts to control the boiler output, coordinating the steam turbine to change the unit load, and finally achieves the load change required by the frequency regulation command and responds to the frequency regulation command. The primary frequency regulation command of the power grid requires the unit to respond as quickly as possible, but the traditional control methods, especially the boiler coordinated control method, respond slowly and are easily evaluated by the power grid.

[0004] In the traditional coal-fired boiler control logic, the cooling water is only used to control the steam temperature. When the steam temperature reaches the target value, the cooling water regulating valve stops working. Only when the steam temperature changes, the cooling water is increased or decreased accordingly. Therefore, when the boiler output change cannot keep up with the unit load change command requirements, the unit cannot respond well to the primary frequency modulation command. Summary of the invention

[0005] The purpose of the present invention is to provide a method for frequency modulation using instantaneous spray flow rate of desuperheating water in a coal-fired unit boiler, so as to solve the problem in the prior art that the timeliness and accuracy of power grid frequency modulation is affected by the response delay of a primary frequency modulation instruction in a coal-fired unit.

[0006] In order to solve the above problems, the technical solution of the method for frequency modulation of instantaneous spraying water flow rate of desuperheating water of a coal-fired unit boiler of the present invention is: The method for frequency modulation of instantaneous spray flow rate of desuperheating water of a coal-fired unit boiler comprises the following steps: S1, determining the increase or decrease of the unit load corresponding to the primary frequency modulation instruction in the DCS control system corresponding to the boiler of the coal-fired unit; S2, add a boiler desuperheating water instantaneous control logic to the primary frequency modulation command response control logic configuration in the DCS control system, so that it can be controlled according to the increase or decrease of the unit load; S3, applying the boiler desuperheating water instantaneous control logic to the desuperheating water regulating valve opening in the DCS control system to achieve desuperheating water instantaneous spray flow control; The instantaneous control logic of boiler desuperheating water includes: control logic for instantaneously opening the desuperheating water regulating valve opening and control logic for instantaneous desuperheating water spray flow rate.

[0007] Furthermore, the control process of the control logic for instantaneously opening the desuperheating water regulating valve opening includes: instantaneously opening and increasing or decreasing the desuperheating water regulating valve opening according to the increase or decrease of the unit load; The control process of the control logic of the instantaneous spray flow rate of the desuperheating water includes: controlling the instantaneous spray flow rate of the boiler desuperheating water according to increasing or decreasing the opening of the desuperheating water regulating valve so that the load quickly reaches the required load point.

[0008] Furthermore, the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, the cooling water regulating valve is opened instantly and the opening is reduced, thereby reducing the instantaneous spray flow of cooling water and allowing the load to be quickly reduced to the required load point.

[0009] Furthermore, the desuperheating water valve opening includes a conventional desuperheating water valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water is instantly opened and opened to increase the instantaneous spray flow of the desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, instantly open and reduce the normal regulating valve opening of the cooling water, reduce the instantaneous spray flow of the cooling water, and quickly reduce the load to the required load point.

[0010] Furthermore, the desuperheating water valve opening also includes the desuperheating water variable load bypass valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water and the variable load bypass regulating valve of the warm water are opened instantly and increased simultaneously, so as to increase the instantaneous spray flow of the desuperheating water and quickly increase the load to the required load point; When reducing the unit load, open instantly and reduce the opening of the conventional desuperheating water regulating valve and the hot water variable load bypass regulating valve at the same time, reduce the instantaneous spray flow of desuperheating water and quickly reduce the load to the required load point.

[0011] Furthermore, the control process of the boiler cooling water instantaneous control logic also includes: when the unit load is increased or reduced, the steam flow required for the unit load change is calculated according to the increase or decrease of the unit load obtained by a primary frequency modulation instruction, thereby increasing the instantaneous water spray flow of the cooling water or reducing the instantaneous water spray flow of the cooling water.

[0012] Furthermore, the steam flow required for the change in unit load is calculated based on the increase or decrease in unit load obtained from the primary frequency modulation instruction, including: Based on the flow-load control function, which is a function for calculating the steam flow required for the primary frequency modulation load instruction change, the steam flow required for the unit load change is calculated; the calculation formula for the steam flow required for the unit load change is shown in Formula 1: Q = f (Δp) = a * (ΔP) 2 +b*ΔP+cFormula 1 Among them, Q is the steam flow required for unit load change, ΔP is the variable load instruction, a, b, c are constants obtained by fitting the unit variable load test.

[0013] Furthermore, the boiler desuperheating water instantaneous control logic also includes control logic for restoring the desuperheating water valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point, and then the desuperheating water regulating valve opening is restored; When reducing the unit load, open and reduce the opening of the cooling water regulating valve instantly, reduce the instantaneous spray flow of the cooling water, so that the load is quickly reduced to the required load point, and then restore the opening of the cooling water regulating valve.

[0014] In order to solve the above problems, the present invention also provides a technical solution of utilizing the instantaneous spray flow rate frequency modulation system of the desuperheating water of the coal-fired unit boiler: The instantaneous spray water flow frequency modulation system of the coal-fired unit boiler desuperheating water includes: unit load system, boiler desuperheating water instantaneous control system and desuperheating water valve opening system. The unit load system is used in the DCS control system corresponding to the coal-fired unit boiler to receive a primary frequency modulation instruction, determine the increase or decrease of the unit load and issue a unit load instruction; The boiler desuperheating water instantaneous control system is connected to the unit load system and to the desuperheating water valve opening system, and is used to receive the unit load instruction and control the instantaneous desuperheating water spray flow rate according to the increase or decrease of the unit load; The desuperheating water valve opening system is connected to the boiler desuperheating water instantaneous control system and is used to realize instantaneous desuperheating water spraying according to the boiler desuperheating water instantaneous control system.

[0015] Furthermore, the frequency modulation system also includes a turbine valve control system, a boiler coordination control system and a load change response system. The turbine valve regulating system is connected to the unit load system and the load change response system, and is used to receive the unit load instruction and realize the load change; The boiler coordination control system is connected to the unit load system and to the load change response system, and is used to receive the unit load instruction and control the boiler output to achieve load change; The load change response system is connected to the desuperheating water valve opening system, the steam turbine valve opening system and the boiler coordinated control system, and is used to receive the load change and then respond to the primary frequency modulation instruction.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The instantaneous spray flow rate of desuperheating water of the boiler of the coal-fired unit is controlled by the method and system of frequency modulation using the instantaneous spray flow rate of desuperheating water of the boiler of the coal-fired unit. By adding a boiler desuperheating water instantaneous control logic to the traditional primary frequency modulation instruction response control logic, and applying it to the desuperheating water regulating valve opening in the DCS control system, the desuperheating water regulating valve opening is instantly opened or closed to realize the instantaneous spray flow rate control of desuperheating water, thereby controlling the steam flow entering the steam turbine instantly, realizing the rapid change of the unit load, and better responding to the primary frequency modulation signal of the unit. The frequency modulation method using the instantaneous spray flow rate of desuperheating water of the boiler of the coal-fired unit has a fast adjustment speed and a safe process, and can be applied to most coal-fired units.

[0017] The control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, the cooling water regulating valve is instantly opened and the opening is reduced, reducing the instantaneous spray flow of cooling water so that the load can be quickly reduced to the required load point, effectively realizing the control of the instantaneous spray flow of cooling water, and the operation is simple.

[0018] The desuperheating water valve opening includes the conventional desuperheating water valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water is instantly opened and opened to increase the instantaneous spray flow of the desuperheating water so that the load is quickly increased to the required load point; When the unit load is reduced, the conventional regulating valve opening of the desuperheating water is instantly opened and reduced, reducing the instantaneous spray flow of the desuperheating water so that the load can be quickly reduced to the required load point. It directly uses the original conventional regulating valve opening of warm water, does not require additional control, and has a simple structure.

[0019] The desuperheating water regulating valve opening also includes the desuperheating water variable load bypass regulating valve opening, and the control process of the control logic of the desuperheating water instantaneous spray flow rate includes: When the unit load is increased, the conventional regulating valve of the desuperheating water and the variable load bypass regulating valve of the warm water are instantly opened and increased to increase the instantaneous spray flow of the desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, the opening of the conventional regulating valve of the desuperheating water and the opening of the variable load bypass regulating valve of the warm water are instantly opened and reduced, reducing the instantaneous spray flow of the desuperheating water so that the load can be quickly reduced to the required load point. By setting the opening of the variable load bypass regulating valve of the desuperheating water, it can act simultaneously with the opening of the conventional regulating valve of the warm water, thereby realizing an instantaneous and rapid change in the desuperheating water flow.

[0020] The control process of the boiler cooling water instantaneous control logic also includes: when the unit load is increased or reduced, the steam flow required for the unit load change is calculated based on the increase or decrease in the unit load obtained by a primary frequency modulation instruction, thereby increasing the cooling water instantaneous spray flow rate or reducing the cooling water instantaneous spray flow rate, so as to more accurately control the cooling water instantaneous spray flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a principle diagram of a method for frequency modulation of instantaneous water spraying flow rate of desuperheating water of a coal-fired unit boiler according to an embodiment of the present application; Figure 2 A diagram of a desuperheating water valve opening system in a desuperheating water instantaneous spray flow frequency modulation system for a coal-fired unit boiler according to an embodiment of the present application; In the figure, 1. conventional cooling water regulating valve, 2. cooling water bypass quick closing valve, 3. feed water, 4. boiler cooling water. DETAILED DESCRIPTION

[0022] As cited in the background art, in the prior art, the primary frequency regulation command response delay in the coal-fired unit affects the timeliness and accuracy of the grid frequency regulation. Therefore, the method for frequency modulation of instantaneous spray flow rate of desuperheating water of the boiler of the coal-fired unit includes the following steps: first, determining the increase or decrease of the unit load corresponding to the primary frequency modulation instruction in the DCS control system corresponding to the boiler of the coal-fired unit, so as to realize load response according to the increase or decrease of the unit load; second, adding the instantaneous control logic of the boiler desuperheating water in the primary frequency modulation instruction response control logic configuration in the DCS control system, so that it is controlled according to the increase or decrease of the unit load; finally, applying the instantaneous control logic of the boiler desuperheating water to the desuperheating water regulating valve opening in the DCS control system, the instantaneous control logic of the boiler desuperheating water includes: the control logic of instantaneously opening the desuperheating water regulating valve opening and the control logic of the instantaneous spray flow rate of the desuperheating water, that is, realizing the instantaneous spray flow rate control of the desuperheating water by instantaneously opening or closing the desuperheating water regulating valve opening, thereby controlling the steam flow rate instantly entering the turbine, realizing the rapid change of the unit load, and better responding to the primary frequency modulation signal of the unit. The method of frequency modulation of instantaneous water spray flow rate of desuperheating water of the coal-fired unit boiler has fast adjustment speed and safe process, and can be applied to most coal-fired units.

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] The following describes, with reference to the accompanying drawings, a method and system for frequency modulation of instantaneous spray flow rate of desuperheating water in a coal-fired unit boiler according to an embodiment of the present application.

[0026] Combine the following Figure 1, the method for frequency modulation of instantaneous water spray flow rate using desuperheating water of a coal-fired unit boiler provided in this application is described in detail. Figure 1 This is a schematic diagram of a method for frequency modulation of instantaneous water spray flow rate of desuperheating water in a coal-fired unit boiler according to an embodiment of the present application.

[0027] like Figure 1 As shown, the method for frequency modulation of instantaneous spray flow rate of desuperheating water of a coal-fired unit boiler according to an embodiment of the present invention includes: first, determining the increase or decrease of the unit load corresponding to a frequency modulation instruction in the DCS control system corresponding to the coal-fired unit boiler; second, adding a boiler desuperheating water instantaneous control logic to the frequency modulation instruction response control logic configuration in the DCS control system, so that it is controlled according to the increase or decrease of the unit load; finally, applying the boiler desuperheating water instantaneous control logic to the desuperheating water regulating valve opening in the DCS control system to realize the desuperheating water instantaneous spray flow rate control. Among them, the boiler desuperheating water instantaneous control logic includes: the control logic for instantaneously opening the desuperheating water regulating valve opening and the control logic for the instantaneous spray flow rate of desuperheating water.

[0028] Specifically, the control process of the control logic for instantaneously opening the desuperheating water regulating valve opening includes: instantly opening and increasing or decreasing the desuperheating water regulating valve opening according to the increase or decrease of the unit load; the control process of the control logic for the instantaneous desuperheating water spray flow rate includes: controlling the instantaneous desuperheating water spray flow rate of the boiler according to increasing or decreasing the desuperheating water regulating valve opening so that the load quickly reaches the required load point.

[0029] The control process of boiler desuperheating water instantaneous control logic includes: First, determine the increase or decrease of the unit load corresponding to the primary frequency modulation instruction in the DCS control system corresponding to the boiler of the coal-fired unit; Secondly, add a boiler desuperheating water instantaneous control logic to the primary frequency modulation instruction response control logic configuration in the DCS control system, and apply it to the desuperheating water valve opening in the DCS control system; Finally, when the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, the cooling water regulating valve is opened instantly and the opening is reduced, thereby reducing the instantaneous spray flow of cooling water and allowing the load to be quickly reduced to the required load point.

[0030] In a specific embodiment of the present application, the desuperheating water valve opening includes the desuperheating water conventional valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water is instantly opened and opened to increase the instantaneous spray flow of the desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, instantly open and reduce the normal regulating valve opening of the cooling water, reduce the instantaneous spray flow of the cooling water, and quickly reduce the load to the required load point.

[0031] In another specific embodiment of the present application, the desuperheating water valve opening also includes the desuperheating water variable load bypass valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water and the variable load bypass regulating valve of the warm water are opened instantly and increased simultaneously, so as to increase the instantaneous spray flow of the desuperheating water and quickly increase the load to the required load point; When reducing the unit load, open instantly and reduce the opening of the conventional desuperheating water regulating valve and the hot water variable load bypass regulating valve at the same time, reduce the instantaneous spray flow of desuperheating water and quickly reduce the load to the required load point.

[0032] In another specific embodiment of the present application, the control process of the boiler desuperheating water instantaneous control logic further includes: when increasing the unit load or reducing the unit load, the steam flow required for the unit load change is calculated according to the increase or decrease of the unit load obtained by the primary frequency modulation instruction, thereby increasing the instantaneous spray flow of desuperheating water or reducing the instantaneous spray flow of desuperheating water. Specifically, the steam flow required for the unit load change is calculated according to the increase or decrease of the unit load obtained by the primary frequency modulation instruction, including: Based on the flow-load control function, which is a function for calculating the steam flow required for the primary frequency modulation load instruction change, the steam flow required for the unit load change is calculated; the calculation formula for the steam flow required for the unit load change is shown in Formula 1: Q = f (Δp) = a * (ΔP) 2 +b*ΔP+cFormula 1 Among them, Q is the steam flow required for unit load change, ΔP is the variable load instruction, a, b, c are constants obtained by fitting the unit variable load test.

[0033] In another specific embodiment of the present application, the boiler desuperheating water instantaneous control logic also includes control logic for restoring the desuperheating water valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point, and then the desuperheating water regulating valve opening is restored; When the unit load is reduced, the cooling water regulating valve opening system is instantly opened and reduced to reduce the instantaneous spray flow of cooling water so that the load is quickly reduced to the required load point, and then the cooling water regulating valve opening is restored.

[0034] like Figure 1 As shown, the specific implementation process is: When the primary frequency modulation instruction requires the unit to increase the load, in the primary frequency modulation instruction response control logic configuration in the DCS control system, the steam turbine regulating valve receives the unit load instruction and opens. Based on the flow-load control function, it is a function for calculating the steam flow required for the primary frequency modulation load instruction change, and then the required increased instantaneous spray flow of the desuperheating water is calculated; at the same time, the unit load instruction acts on the instantaneous control of the boiler desuperheating water to instantly increase the opening of the conventional regulating valve of the boiler desuperheating water and the opening of the warm water variable load bypass regulating valve. Due to the heat storage characteristics of the boiler, the steam flow will increase instantly, the steam pressure will increase, and the load increase amount and speed are much greater than simply opening the steam turbine regulating valve, which is conducive to the rapid change of the load to the load point required by the instruction, and realizes a rapid response to the primary frequency modulation instruction; at this time, the opening of the conventional regulating valve of the unit desuperheating water and the opening of the warm water variable load bypass regulating valve return to their original positions, and the boiler coordinated control keeps up, so that the unit load is kept stable; When the frequency modulation instruction requires load reduction, in the primary frequency modulation instruction response control logic configuration in the DCS control system, the steam turbine regulating valve receives the unit load instruction to open the action, and at the same time, based on the flow-load control function, it is a function for calculating the steam flow required for the primary frequency modulation load instruction change, and then calculates the required reduction in the instantaneous spray flow of the desuperheating water; the unit load instruction acts on the instantaneous control of the boiler desuperheating water to instantly increase the opening of the conventional regulating valve of the boiler desuperheating water and the opening of the warm water variable load bypass regulating valve, instantly reducing the boiler desuperheating water spray, and further reducing the steam flow. The load reduction amount and reduction speed are also much faster than simply closing the steam turbine regulating valve. Similarly, when it changes quickly to the load point required by the instruction, a rapid response to the primary frequency modulation instruction is achieved; at this time, the unit desuperheating water conventional regulating valve opening unit and the warm water variable load bypass regulating valve opening unit return to their original positions, and the boiler coordinated control keeps up to keep the unit load stable.

[0035] Based on the above method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler, the instantaneous water spray flow rate frequency modulation system of the present invention is as follows: Figure 2 As shown, it includes: a unit load system, a boiler cooling water instantaneous control system and a cooling water valve opening system. The unit load system is used in the DCS control system corresponding to the coal-fired unit boiler to receive a frequency modulation instruction, determine the increase or decrease of the unit load and issue a unit load instruction; the boiler cooling water instantaneous control system is connected to the unit load system and to the cooling water valve opening system, and is used to receive the unit load instruction and control the instantaneous cooling water spray flow rate according to the increase or decrease of the unit load; the cooling water valve opening system is connected to the boiler cooling water instantaneous control system, and is used to realize the instantaneous cooling water spray according to the boiler cooling water instantaneous control system.

[0036] Specifically, the desuperheating water valve opening system includes a desuperheating water conventional valve opening unit and a hot water variable load bypass valve opening unit, that is, the desuperheating water conventional valve opening unit is a conventional desuperheating water regulating valve 1, and the hot water variable load bypass regulating valve opening unit is a desuperheating water bypass fast closing valve 2. The boiler desuperheating water instantaneous control system receives the unit load command and issues a desuperheating water frequency modulation instantaneous command, which acts on the conventional desuperheating water regulating valve 1 and the desuperheating water bypass fast closing valve 2 at the same time, and the incoming water 3 passes through the conventional desuperheating water regulating valve 1 and the desuperheating water bypass fast closing valve 2 to control the desuperheating water flow rate and deliver the boiler desuperheating water 4, thereby realizing the instantaneous and rapid change of the desuperheating water flow rate.

[0037] The specific implementation process is: When a frequency modulation instruction requires the unit to increase the load, first, the unit load system receives the frequency modulation instruction and issues a unit load increase instruction; secondly, the boiler cooling water instantaneous control system receives the unit load instruction and instantly opens the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2 at the same time, and the incoming water 3 passes through the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2 to achieve rapid control of the cooling water flow rate and provide boiler cooling water 4, instantly increasing the boiler cooling water 4 spray water. Due to the heat storage characteristics of the boiler, the steam flow rate will increase instantly, the steam pressure will increase, and the load will change rapidly to the load point required by the instruction, realizing a rapid response to the frequency modulation instruction; finally, the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2 return to their original positions, and the boiler coordinated control keeps up, so that the unit load is kept stable; When a frequency modulation instruction requires the unit to reduce the load, first, the unit load system receives the frequency modulation instruction and issues a unit load reduction instruction; secondly, the boiler cooling water instantaneous control system receives the unit load instruction and instantly closes the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2, and the incoming water 3 passes through the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2 to achieve rapid control of the cooling water flow rate and supply boiler cooling water 4, instantly reducing the boiler cooling water 4 spray water, further reducing the steam flow rate, and quickly changing the load to the load point required by the instruction, thereby achieving a rapid response to the frequency modulation instruction; finally, the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2 return to their original positions, and the boiler coordinated control keeps up, so that the unit load is kept stable.

[0038] In another embodiment of the present application, the frequency regulation system also includes a steam turbine valve regulating system, a boiler coordinated control system and a load change response system, the steam turbine valve regulating system is connected to the unit load system and to the load change response system, and is used to receive the unit load command and realize the load change; the boiler coordinated control system is connected to the unit load system and to the load change response system, and is used to receive the unit load command and control the boiler output to realize the load change; the load change response system is connected to the cooling water valve opening system, the steam turbine valve regulating system and the boiler coordinated control system, and is used to receive the load change and respond to a frequency regulation command.

[0039] The specific implementation process is: When a frequency modulation instruction requires the unit to increase the load, first, the unit load system receives the frequency modulation instruction and issues a unit load increase instruction; secondly, the steam turbine regulating valve system receives the instruction to open the regulating valve, and the boiler cooling water instantaneous control system receives the unit load instruction and instantly opens the conventional cooling water regulating valve 1 and the cooling water bypass quick-closing valve 2. Due to the heat storage characteristics of the boiler, the steam flow rate will increase instantly, the steam pressure will increase, and the load will change rapidly to the load point required by the instruction; finally, the conventional cooling water regulating valve 1 and the cooling water bypass quick-closing valve 2 return to their original positions, receive the unit load instruction, control the boiler output, and thus realize the load change, so that the unit load is kept stable; the load change response system receives the load change and then responds to the frequency modulation instruction.

[0040] When a frequency modulation instruction requires the unit to reduce the load, first, the unit load system receives the frequency modulation instruction and issues a unit load reduction instruction; secondly, the steam turbine regulating valve system receives the instruction to open the regulating valve, and the boiler cooling water instantaneous control system receives the unit load instruction and instantly closes the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2, instantly reducing the boiler cooling water spray, further reducing the steam flow, and the load changes rapidly to the load point required by the instruction; finally, the conventional cooling water regulating valve 1 and the cooling water bypass quick closing valve 2 return to their original positions, receive the unit load instruction and control the boiler to keep the unit load stable; the load change response system receives the load change and then responds to the primary frequency modulation instruction.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler, characterized in that: The following steps are involved: S1, determining the increase or decrease of the unit load corresponding to the primary frequency modulation instruction in the DCS control system corresponding to the boiler of the coal-fired unit; S2, add a boiler desuperheating water instantaneous control logic to the primary frequency modulation command response control logic configuration in the DCS control system, so that it can be controlled according to the increase or decrease of the unit load; S3, applying the boiler desuperheating water instantaneous control logic to the desuperheating water regulating valve opening in the DCS control system to achieve desuperheating water instantaneous spray flow control; The instantaneous control logic of boiler desuperheating water includes: control logic for instantaneously opening the desuperheating water regulating valve opening and control logic for instantaneous desuperheating water spray flow rate.

2. The method for frequency modulation of instantaneous water spray flow rate of coal-fired unit boiler desuperheating water according to claim 1 is characterized in that: The control process of the control logic for instantaneously opening the desuperheating water regulating valve opening includes: instantaneously opening and increasing or decreasing the desuperheating water regulating valve opening according to the increase or decrease of the unit load; The control process of the control logic of the instantaneous spray flow rate of the desuperheating water includes: controlling the instantaneous spray flow rate of the boiler desuperheating water according to increasing or decreasing the opening of the desuperheating water regulating valve so that the load quickly reaches the required load point.

3. The method for frequency modulation of instantaneous water spray flow rate of coal-fired unit boiler desuperheating water according to claim 2 is characterized in that: The control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, the cooling water regulating valve is opened instantly and the opening is reduced, thereby reducing the instantaneous spray flow of cooling water and allowing the load to be quickly reduced to the required load point.

4. The method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler according to claim 3 is characterized in that: The desuperheating water valve opening includes the conventional desuperheating water valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water is instantly opened and opened to increase the instantaneous spray flow of the desuperheating water so that the load is quickly increased to the required load point; When reducing the unit load, instantly open and reduce the normal regulating valve opening of the cooling water, reduce the instantaneous spray flow of the cooling water, and quickly reduce the load to the required load point.

5. The method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler according to claim 4 is characterized in that: The desuperheating water regulating valve opening also includes the desuperheating water variable load bypass regulating valve opening, and the control process of the boiler desuperheating water instantaneous control logic includes: When the unit load is increased, the conventional regulating valve of the desuperheating water and the variable load bypass regulating valve of the warm water are opened instantly and increased simultaneously, so as to increase the instantaneous spray flow of the desuperheating water and quickly increase the load to the required load point; When reducing the unit load, open instantly and reduce the opening of the conventional desuperheating water regulating valve and the hot water variable load bypass regulating valve at the same time, reduce the instantaneous spray flow of desuperheating water and quickly reduce the load to the required load point.

6. The method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler according to claim 5 is characterized in that: The control process of the boiler cooling water instantaneous control logic also includes: when the unit load is increased or reduced, the steam flow required for the unit load change is calculated based on the increase or decrease of the unit load obtained by a primary frequency modulation instruction, thereby increasing the instantaneous cooling water spray flow rate or reducing the instantaneous cooling water spray flow rate.

7. The method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler according to claim 6 is characterized in that: The steam flow required for the change in unit load calculated by increasing or decreasing the unit load obtained according to the primary frequency modulation instruction includes: Based on the flow-load control function, which is a function for calculating the steam flow required for the primary frequency modulation load instruction change, the steam flow required for the unit load change is calculated; the calculation formula for the steam flow required for the unit load change is shown in Formula 1: Q = f(Δp) = a*(ΔP) 2 + b*ΔP + c Equation 1 Among them, Q is the steam flow required for unit load change, ΔP is the variable load instruction, a, b, c are constants obtained by fitting the unit variable load test.

8. The method for frequency modulation of instantaneous water spray flow rate of desuperheating water of a coal-fired unit boiler according to any one of claims 3 to 7, characterized in that: The instantaneous control logic of the boiler desuperheating water also includes the control logic for restoring the opening of the desuperheating water regulating valve. The control process of the instantaneous control logic of the boiler desuperheating water includes: When the unit load is increased, the desuperheating water regulating valve is instantly opened and opened to increase the instantaneous spray flow of desuperheating water so that the load is quickly increased to the required load point, and then the desuperheating water regulating valve opening is restored; When reducing the unit load, open and reduce the opening of the cooling water regulating valve instantly, reduce the instantaneous spray flow of the cooling water, so that the load is quickly reduced to the required load point, and then restore the opening of the cooling water regulating valve.

9. The instantaneous spray flow frequency modulation system of the desuperheating water of the coal-fired unit boiler is characterized in that: The method for frequency modulation of instantaneous spraying water flow rate of desuperheating water of a coal-fired unit boiler according to any one of claims 1 to 8 comprises: a unit load system, a boiler desuperheating water instantaneous control system and a desuperheating water valve opening system, The unit load system is used in the DCS control system corresponding to the coal-fired unit boiler to receive a primary frequency modulation instruction, determine the increase or decrease of the unit load and issue a unit load instruction; The boiler desuperheating water instantaneous control system is connected to the unit load system and to the desuperheating water valve opening system, and is used to receive the unit load instruction and control the instantaneous desuperheating water spray flow rate according to the increase or decrease of the unit load; The desuperheating water valve opening system is connected to the boiler desuperheating water instantaneous control system and is used to realize instantaneous desuperheating water spraying according to the boiler desuperheating water instantaneous control system.

10. The frequency modulation system for instantaneous water spraying flow rate of coal-fired unit boiler desuperheating water according to claim 9 is characterized in that: The frequency modulation system also includes a turbine valve control system, a boiler coordination control system and a load change response system. The turbine valve regulating system is connected to the unit load system and the load change response system, and is used to receive the unit load instruction and realize the load change; The boiler coordination control system is connected to the unit load system and to the load change response system, and is used to receive the unit load instruction and control the boiler output to achieve load change; The load change response system is connected to the desuperheating water valve opening system, the steam turbine valve opening system and the boiler coordination control system, and is used to receive the load change amount and then respond to a frequency modulation instruction.

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