Control method and system for dynamic and static combined correction of main steam pressure deviation of secondary reheating unit

Abstract

The invention discloses a control method and system for dynamic and static combined correction of main steam pressure deviation of a secondary reheating unit. The control method comprises the steps that dynamic correction is conducted under the continuous variable load working condition, and the final main steam pressure dynamic feedforward correction control quantity is obtained; performing static correction under a stable load working condition to obtain a static correction control quantity; whole-course pressure correction is conducted in the dynamic and static process, and a feed water flow set correction value is obtained; the main steam pressure set value and the main feed water flow set value are corrected in real time according to the final main steam pressure dynamic feedforward correction control quantity, the static correction control quantity and the feed water flow set correction value in combination with the unit working condition; main steam pressure correction amplitude constraint and correction rate constraint are given according to the threshold function with the actual load as the reference and the actual operation condition of equipment. The response of the main steam pressure of the secondary reheating unit can be improved, and the peak regulation and frequency modulation capacity of the unit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power generation, and in particular relates to a control method and system for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit. Background Art

[0002] In the process of thermal power generation, the control of main steam pressure is a key link, which directly affects the power generation efficiency and the safe operation of equipment. By controlling the main steam pressure, the thermal power generation process can be optimized, the energy utilization efficiency can be improved, and the equipment can be ensured to operate within a safe range to avoid equipment damage or safety accidents caused by pressure fluctuations.

[0003] At present, in the face of the frequent changes in the load response requirements of the power grid, under the influence of coal quality and furnace heat storage, the main steam pressure is prone to large deviations from the set value and slow load response of the unit during the operating condition change. Therefore, in the process of frequent load changes, quickly stabilizing the unit operating condition migration to a new equilibrium point, improving the main steam pressure response speed, and reducing the frequent fluctuations of the main steam pressure are one of the problems that need to be solved urgently at this stage of thermal power generation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a control method and system for dynamic and static combined correction of the main steam pressure deviation of a secondary reheat unit, which can quickly stabilize the unit operating condition at a new equilibrium point during frequent load changes, so as to improve the main steam pressure response speed and reduce the frequent fluctuations of the main steam pressure.

[0005] To this end, a technical solution adopted by the present invention is: a control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit, which comprises:

[0006] Step 1: In the TF (machine-to-furnace control) mode of the unit, the main steam pressure setting function tracks the actual load generation of the unit; in the CCS (machine-to-furnace coordinated control) mode of the unit, the main steam pressure setting function tracks the load instruction generation of the unit;

[0007] Step 2: Perform dynamic correction under continuously variable load conditions to obtain the final main steam pressure dynamic feedforward correction control amount; perform static correction under stable load conditions to obtain the static correction control amount; perform full-process pressure correction in the dynamic and static processes to obtain the feedwater flow setting correction value;

[0008] Step 3, in combination with the unit operating conditions, the main steam pressure setting value and the main feed water flow setting value are corrected in real time according to the final main steam pressure dynamic feedforward correction control amount, the static correction control amount and the feed water flow setting correction value;

[0009] Step 4: According to the threshold function based on the actual load and the actual operation of the equipment, the main steam pressure correction amplitude constraint and the correction rate constraint are given.

[0010] The correction object of dynamic correction under continuously variable load conditions and static correction under stable load conditions is the main steam pressure setting value, and the correction object of full-process pressure correction in dynamic and static processes is the main feed water flow setting value.

[0011] Further, in step 1, under the unit TF mode, the main steam pressure setting function tracks the actual load x of the unit. LD Generate; in the CCS mode of the unit, the main steam pressure setting function tracks the unit load instruction x LDD Generate, expressed as follows:

[0012]

[0013] Where, SP m is the main steam pressure setting value, and f(x) is the main steam pressure setting function.

[0014] Furthermore, in step 2, the dynamic correction under the continuously variable load condition is specifically as follows: the number of same-direction changes under the continuously variable load condition is recorded in real time using a variable load condition register, a same-direction correction coefficient is generated according to the number of same-direction changes, and the final main steam pressure dynamic feedforward correction control amount ΔSP is obtained by combining the dynamic pressure correction function. 动态 .

[0015] Furthermore, the final main steam pressure dynamic feedforward correction control amount ΔSP 动态 The calculation formula is as follows:

[0016]

[0017] Where, e is the main steam pressure deviation value, N1 is the dynamic pressure correction function under high load, α1 is the same direction correction coefficient function under high load, N2 is the dynamic pressure correction function under low load, α2 is the same direction correction coefficient function under low load, n is the number of same direction recorded by the register, x LD Indicates the actual load of the unit.

[0018] Furthermore, in step 2, the static correction under the stable load condition is specifically as follows: when the static pressure deviation reaches the threshold, the correction delay timer is activated, and when the timer ends, the static pressure correction controller is activated to correct the main steam pressure setting value, and the static correction control amount ΔSP is generated according to the static pressure deviation correction function. 静态 .

[0019] Furthermore, when |e|>z1, and When the correction delay timer starts timing, the static pressure correction controller is activated to correct the main steam pressure setting value after the timing ends. The static correction control amount ΔSP 静态 for:

[0020]

[0021] e is the main steam pressure deviation value, z1 is the main steam pressure deviation value amplitude threshold, d PV is the differential of the main steam pressure, z2 is the threshold value of the change rate of the actual value of the main steam pressure, N3 is the static pressure correction function, β1 is the static correction coefficient function corresponding to the load, and t is the differential action time.

[0022] Furthermore, in step 2, the full-range pressure correction in the dynamic and static processes is specifically as follows: with appropriate superheat as a prerequisite, when the main steam pressure deviation reaches a threshold, the full-range pressure correction controller is activated, and a feed water flow setting correction value is generated according to the full-range pressure deviation correction function.

[0023] Furthermore, the full-range pressure correction controller is activated to generate a water flow setting correction value ΔSP according to the full-range pressure deviation correction function. w :

[0024] ΔSP w =N4(e)β2(x LD )δ(T), |e|>c1 and c2≤T≤c3

[0025] c1 is the main steam pressure deviation amplitude threshold, c2 is the superheat lower limit threshold, c3 is the superheat upper limit threshold, N4 is the full-range pressure correction function, β2 is the full-range correction coefficient function corresponding to the load, and δ is the full-range correction coefficient function corresponding to the superheat.

[0026] Furthermore, in step 3, the main steam pressure setting value SP m and main feedwater flow setting value SP w Real-time correction is performed, and the corrected main steam pressure setting value SP m修 and the corrected main feedwater flow setting value SP w修 for:

[0027]

[0028] Where, ΔSP 动态 is the dynamic feedforward correction control amount of the final main steam pressure, ΔSP 静态 is the static correction control quantity, ΔSP w Set a correction value for the feedwater flow rate.

[0029] The present invention also provides a control system for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit, which is used to implement the control method for dynamic and static combined correction of main steam pressure deviation of the secondary reheat unit, comprising:

[0030] Reference set value generation unit: In the TF mode of the unit, the main steam pressure setting function tracks the actual load generation of the unit; in the CCS mode of the unit, the main steam pressure setting function tracks the load instruction generation of the unit;

[0031] Correction value acquisition unit: Perform dynamic correction under continuously variable load conditions to obtain the final main steam pressure dynamic feedforward correction control amount; perform static correction under stable load conditions to obtain the static correction control amount; perform full-process pressure correction in the dynamic and static processes to obtain the feedwater flow setting correction value;

[0032] Correction set unit: In combination with the unit operating conditions, the main steam pressure set value and the main feed water flow set value are corrected in real time according to the final main steam pressure dynamic feedforward correction control amount, the static correction control amount and the feed water flow setting correction value;

[0033] Correction amplitude limit and speed limit unit: According to the threshold function based on the actual load and the actual operation of the equipment, the correction amplitude constraint and correction rate constraint of the main steam pressure are given.

[0034] The present invention has the following beneficial effects: in the process of frequent load changes, the present invention can quickly stabilize the unit operating condition migration at a new equilibrium point, improve the main steam pressure response speed, and reduce the frequent fluctuations of the main steam pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 1 is a flow chart of a control method for combining dynamic and static correction of main steam pressure deviation of a double reheat unit in accordance with Embodiment 1 of the present invention;

[0036] Figure 2 It is a structural diagram of a control system for combining dynamic and static correction of main steam pressure deviation of a secondary reheat unit in Example 2 of the present invention. DETAILED DESCRIPTION

[0037] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0038] Example 1

[0039] As attached Figure 1 As shown, this embodiment provides a control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit, comprising the following steps:

[0040] Step 1: In the TF (machine-to-furnace control) mode, the main steam pressure setting function tracks the actual load x of the unit. LD Generated, in the CCS (coordinated control of boiler and turbine) mode, the main steam pressure setting function tracks the unit load instruction x LDD generate.

[0041] Taking a 1000MW double reheat unit as an example, the load range of the coordinated control of the turbine and boiler is 400MW~1000MW, and the load range of the turbine and boiler control is 0MW~1000MW. The main steam pressure setting value is:

[0042]

[0043] Where, SP m is the main steam pressure setting value, and f(x) is the main steam pressure setting function.

[0044] Step 2, perform dynamic correction under continuously variable load conditions, static correction under stable load conditions, and full-range pressure correction in dynamic and static processes. The correction objects of dynamic correction under continuously variable load conditions and static correction under stable load conditions are the main steam pressure setting value, and the correction object of full-range pressure correction in dynamic and static processes is the main feedwater flow setting value.

[0045] Among them, for the 1000MW secondary reheat unit from 730MW→750MW→780MW→820MW to the stable operating condition, the functions of each correction circuit are as follows:

[0046] Dynamic correction under continuously variable load conditions: The main steam pressure deviation is 1MPa: The number of same-direction changes in the variable load condition register is recorded as 3 times. The same-direction correction coefficient is generated according to the number of same-direction changes, and combined with the same-direction pressure correction function, the final main steam pressure dynamic feedforward correction control amount ΔSP is obtained. 动态 :

[0047] ΔSP 动态 =N1(1)α1(3),x LD ≥70%

[0048] Where N1 is the dynamic pressure correction function under high load, and α1 is the same direction correction coefficient function under high load.

[0049] Moreover, after the 1000MW secondary reheat unit reaches a stable state under the continuously variable load condition, the main steam pressure deviation reaches 0.8MPa. According to the static correction deviation amplitude threshold z1 set by the unit is 0.8MPa, and the actual main steam pressure change rate threshold z2 is 0.2MPa / min, the activation requirement of the static pressure correction controller has been met, and the correction delay timer starts timing. After the timing ends, the static pressure correction controller is activated to correct the main steam pressure set value. The static correction control amount ΔSP 静态 for:

[0050]

[0051] Where N3 is the static pressure correction function, β1 is the static correction coefficient function corresponding to the load, and t is the differential action time.

[0052] During the entire process of the above-mentioned operating condition changes, the full-range pressure correction controller performs real-time output according to the changes in load and pressure, activates the full-range pressure correction controller, and generates the water flow setting correction value ΔSP according to the full-range pressure deviation correction function. w :

[0053] ΔSP w =N4(e)β2(x LD )δ(T), |e|>c1 and c2≤T≤c3

[0054] Wherein, c1 is the main steam pressure deviation amplitude threshold, c2 is the superheat lower limit threshold, c3 is the superheat upper limit threshold, N4 is the full-range pressure correction function, β2 is the full-range correction coefficient function corresponding to the load, and δ is the full-range correction coefficient function corresponding to the superheat.

[0055] Step 3, in combination with the unit operating conditions, the main steam pressure setting value and the main feed water flow setting value are corrected in real time according to the final main steam pressure dynamic feedforward correction control value, the static correction control value and the feed water flow setting correction value.

[0056] Corrected main steam pressure setting value SP for 1000MW double reheat unit during the whole load change process m修 And the corrected main feedwater flow setting value SP w修 for:

[0057]

[0058] Step 4: According to the threshold function based on the actual load and the actual operation of the equipment, the main steam pressure correction amplitude constraint and the correction rate constraint are given.

[0059] The correction amplitude constraint and correction rate constraint set for the 1000MW double reheat unit in Example 1 are threshold functions based on the actual load:

[0060] SP m修 ∈[f1(x LD ),f2(x LD )]

[0061]

[0062] In the formula, f1(x LD )、f2(x LD ) are respectively the upper limit function and lower limit function of the correction amplitude constraint of the main steam pressure after correction, f3(x LD )、f4(x LD ) are the upper limit function and lower limit function of the correction rate constraint of the corrected main steam pressure.

[0063] Example 2

[0064] The present embodiment provides a control system for dynamic and static combined correction of the main steam pressure deviation of a secondary reheat unit, which is used to implement the control method for dynamic and static combined correction of the main steam pressure deviation of a secondary reheat unit described in Example 1, and is composed of a reference set value generation unit, a correction value acquisition unit, a correction set unit and a correction limit and speed limit unit.

[0065] Reference set value generation unit: In the unit TF (machine-to-boiler control) mode, the main steam pressure setting function tracks the actual load generation of the unit; in the unit CCS (machine-to-boiler coordinated control) mode, the main steam pressure setting function tracks the load instruction generation of the unit.

[0066] Correction value acquisition unit: perform dynamic correction under continuously variable load conditions to obtain the final main steam pressure dynamic feedforward correction control quantity; perform static correction under stable load conditions to obtain the static correction control quantity; perform full pressure correction in the dynamic and static processes to obtain the feedwater flow setting correction value.

[0067] Correction set unit: In combination with the unit operating conditions, the main steam pressure set value and the main feed water flow set value are corrected in real time according to the final main steam pressure dynamic feedforward correction control quantity, the static correction control quantity and the feed water flow setting correction value.

[0068] Correction amplitude limit and speed limit unit: According to the threshold function based on the actual load and the actual operation of the equipment, the correction amplitude constraint and correction rate constraint of the main steam pressure are given.

[0069] The correction value acquisition unit is composed of a dynamic correction subunit under continuously variable load conditions, a static correction subunit under stable load conditions, and a full-range pressure correction subunit in dynamic and static processes.

[0070] The dynamic correction subunit under the continuously variable load condition: uses the variable load condition register to record the number of same-direction changes under the continuously variable load condition in real time, generates a same-direction correction coefficient according to the number of same-direction changes, and combines the same-direction pressure correction function to obtain the final main steam pressure dynamic feedforward correction control amount ΔSP 动态 :

[0071]

[0072] Where, e is the main steam pressure deviation value, N1 is the dynamic pressure correction function under high load, α1 is the same direction correction coefficient function under high load, N2 is the dynamic pressure correction function under low load, α2 is the same direction correction coefficient function under low load, n is the number of same direction recorded by the register, x LD Indicates the actual load of the unit.

[0073] The static correction subunit under the stable load condition: when |e|>z1, and When the correction delay timer starts timing, the static pressure correction controller is activated after the timing ends to correct the main steam pressure setting value and generate the static correction control amount ΔSP 静态 :

[0074]

[0075] e is the main steam pressure deviation value, z1 is the main steam pressure deviation value amplitude threshold, d PV is the differential of the main steam pressure, z2 is the threshold value of the change rate of the actual value of the main steam pressure, N3 is the static pressure correction function, β1 is the static correction coefficient function corresponding to the load, and t is the differential action time.

[0076] The full pressure correction subunit in the dynamic and static process: when |e|>c1, and Activate the full-range pressure correction controller and generate the water flow setting correction value ΔSP according to the pressure deviation correction function w :

[0077] ΔSP w =N4(e)β2(x LD )δ(T), |e|>c1 and c2≤T≤c3

[0078] Wherein, c1 is the main steam pressure deviation amplitude threshold, c2 is the superheat lower limit threshold, c3 is the superheat upper limit threshold, N4 is the full-range pressure correction function, β2 is the full-range correction coefficient function corresponding to the load, and δ is the full-range correction coefficient function corresponding to the superheat.

[0079] In the correction set unit, the main steam pressure setting value SP m and main feedwater flow setting value SPw Real-time correction is performed, and the corrected main steam pressure setting value SP m修 and the corrected main feedwater flow setting value SP w修 for:

[0080]

[0081] Where, ΔSP 动态 is the dynamic feedforward correction control amount of the final main steam pressure, ΔSP 静态 is the static correction control quantity, ΔSP w Set a correction value for the feedwater flow rate.

[0082] It should be noted that each unit in the above-mentioned control system for the dynamic and static combined correction of the main steam pressure deviation of a secondary reheat unit can be fully or partially implemented by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the corresponding operations of each of the above modules. For the specific definition of a control system for the dynamic and static combined correction of the main steam pressure deviation of a secondary reheat unit, please refer to the definition of a control method for the dynamic and static combined correction of the main steam pressure deviation of a secondary reheat unit mentioned above. The two have the same functions and effects, which will not be repeated here.

[0083] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit, characterized in that: include: Step 1: In the TF mode of the unit, the main steam pressure setting function tracks the actual load generation of the unit; In the CCS mode of the unit, the main steam pressure setting function tracks the generation of the unit load command; Step 2, performing dynamic correction under continuously variable load conditions to obtain a final main steam pressure dynamic feedforward correction control amount; Perform static correction under stable load conditions to obtain static correction control quantity; Perform full pressure correction in the dynamic and static processes to obtain the set correction value of the water flow rate; Step 3, in combination with the unit operating conditions, the main steam pressure setting value and the main feed water flow setting value are corrected in real time according to the final main steam pressure dynamic feedforward correction control amount, the static correction control amount and the feed water flow setting correction value; Step 4: According to the threshold function based on the actual load and the actual operation of the equipment, the main steam pressure correction amplitude constraint and the correction rate constraint are given.

2. The control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit according to claim 1 is characterized in that: In step 1, in the unit TF mode, the main steam pressure setting function tracks the actual load x of the unit LD Generate; in the CCS mode of the unit, the main steam pressure setting function tracks the unit load instruction x LDD Generate, expressed as follows: Where, SP m is the main steam pressure setting value, and f(x) is the main steam pressure setting function.

3. The control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit according to claim 1, characterized in that: In step 2, the dynamic correction under the continuously variable load condition is specifically as follows: the number of same-direction changes under the continuously variable load condition is recorded in real time using the variable load condition register, a same-direction correction coefficient is generated according to the number of same-direction changes, and the final main steam pressure dynamic feedforward correction control amount ΔSP is obtained by combining the dynamic pressure correction function. 动态 .

4. The control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit according to claim 3 is characterized in that: The final main steam pressure dynamic feedforward correction control amount ΔSP 动态 The calculation formula is as follows: Where, e is the main steam pressure deviation value, N1 is the dynamic pressure correction function under high load, α1 is the same direction correction coefficient function under high load, N2 is the dynamic pressure correction function under low load, α2 is the same direction correction coefficient function under low load, n is the number of same direction recorded by the register, x LD Indicates the actual load of the unit.

5. The control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit according to claim 1, characterized in that: In step 2, the static correction under the stable load condition is specifically as follows: when the static pressure deviation reaches the threshold, the correction delay timer is activated, and after the timer is over, the static pressure correction controller is activated to correct the main steam pressure setting value, and the static correction control amount ΔSP is generated according to the static pressure deviation correction function 静态 .

6. The control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit according to claim 5, characterized in that: When |e|>z1, and When the correction delay timer starts timing, the static pressure correction controller is activated to correct the main steam pressure setting value after the timing ends. The static correction control amount ΔSP 静态 for: e is the main steam pressure deviation value, z1 is the main steam pressure deviation value amplitude threshold, d PV is the differential of the main steam pressure, z2 is the threshold value of the actual value of the main steam pressure change rate, N3 is the static pressure correction function, β1 is the static correction coefficient function corresponding to the load, t is the differential action time, x LD Indicates the actual load of the unit.

7. The control method for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit according to claim 1, characterized in that: In step 2, the full-range pressure correction in the dynamic and static processes is specifically as follows: with appropriate superheat as a prerequisite, when the main steam pressure deviation reaches a threshold, the full-range pressure correction controller is activated, and a feed water flow setting correction value is generated according to the full-range pressure deviation correction function.

8. The control method for dynamic and static combined correction of main steam pressure deviation of a double reheat unit according to claim 7, characterized in that: Activate the full-range pressure correction controller and generate the water flow setting correction value ΔSP according to the full-range pressure deviation correction function w : ΔSP w = N4(e)β2(x LD )δ(T), |e| > c1 and c2 ≤ T ≤ c3 e is the main steam pressure deviation value, c1 is the main steam pressure deviation value amplitude threshold, c2 is the superheat lower limit threshold, c3 is the superheat upper limit threshold, N4 is the full-range pressure correction function, β2 is the full-range correction coefficient function corresponding to the load, δ is the full-range correction coefficient function corresponding to the superheat, x LD Indicates the actual load of the unit.

9. The control method for dynamic and static combined correction of main steam pressure deviation of a double reheat unit according to claim 1, characterized in that: In step 3, the main steam pressure setting value SP m and main feedwater flow setting value SP w Real-time correction is performed, and the corrected main steam pressure setting value SP m修 and the corrected main feedwater flow setting value SP w修 for: Where, ΔSP 动态 is the dynamic feedforward correction control amount of the final main steam pressure, ΔSP 静态 is the static correction control quantity, ΔSP w Set a correction value for the feedwater flow rate.

10. A control system for dynamic and static combined correction of main steam pressure deviation of a secondary reheat unit, characterized in that: include: Benchmark set value generation unit: In the unit TF mode, the main steam pressure setting function tracks the actual load generation of the unit; In the CCS mode of the unit, the main steam pressure setting function tracks the generation of the unit load command; Correction value acquisition unit: performs dynamic correction under continuously variable load conditions to obtain the final main steam pressure dynamic feedforward correction control value; Perform static correction under stable load conditions to obtain static correction control quantity; Perform full pressure correction in the dynamic and static processes to obtain the set correction value of the water flow rate; Correction set unit: In combination with the unit operating conditions, the main steam pressure set value and the main feed water flow set value are corrected in real time according to the final main steam pressure dynamic feedforward correction control amount, the static correction control amount and the feed water flow setting correction value; Correction amplitude limit and speed limit unit: According to the threshold function based on the actual load and the actual operation of the equipment, the correction amplitude constraint and correction rate constraint of the main steam pressure are given.

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