CN104791754A - Supercritical or ultra-supercritical generating set variable-load overshoot control method - Google Patents
Supercritical or ultra-supercritical generating set variable-load overshoot control method Download PDFInfo
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- CN104791754A CN104791754A CN201410165967.5A CN201410165967A CN104791754A CN 104791754 A CN104791754 A CN 104791754A CN 201410165967 A CN201410165967 A CN 201410165967A CN 104791754 A CN104791754 A CN 104791754A
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Abstract
The invention relates to a supercritical or ultra-supercritical generating set variable-load overshoot control method. According to the method, water supply overshooting and coal quantity overshooting are conducted separately, and various overshoots are intelligently generated according to a state of the generating set before the load is varied. The control method particularly comprises the following steps that 1, comparison is conducted between a load command and a real load deviation, whether the deviation is larger than a first constant value is judged, if yes, water supply overshooting is triggered, and the overshoot adopts hierarchical control; 2, comparison is conducted between a real intermediate point enthalpy value and a preset value of the enthalpy value, whether the deviation is larger than a second constant value is judged, if yes, the coal quantity overshooting is triggered, and the overshoot adopts the hierarchical control. Compared with the prior art, by means of the supercritical or ultra-supercritical generating set variable-load overshoot control method, the various overshoots are intelligently generated according to the state of the generating set before the load is varied, and load control and steam temperature control of a turbine high-pressure control valve in sliding pressure operation are well achieved.
Description
Technical field
The present invention relates to automation field that is overcritical or ultra supercritical unit, especially relate to a kind of overcritical or ultra supercritical unit varying duty overshoot control method.
Background technology
Quantity that is overcritical or ultra supercritical thermal power generation unit is increasing, becomes main force's unit of domestic electrical network gradually.The coordinated control mode of unit mostly adopts based on CBF (boiler tracking) or the mode based on CTF (steam turbine tracking), boiler control vapour pressure under CBF mode, steam turbine control load; And under CTF mode, boiler control load, steam turbine control vapour pressure.Because dispatching of power netwoks is more and more higher to fired power generating unit AGC control overflow, unit mainly adopts the control mode based on CBF, to accelerate load responding, improves spatial load forecasting precision.But this mode needs steam turbine pitch to be in throttle, and (when single valve regulates, all pitch all want throttling; When sequence valve regulates, there is throttling in some pitch), sacrifice unit operation economy and meet AGC control overflow.Part of generating units have employed the mode of steam turbine pitch standard-sized sheet sliding pressure operation for this reason, in varying duty, do not participate in Load Regulation or Steam Pressure Control of Circulated directly, is only carried out the change of load-responsive instruction by boiler.Because the thermal inertia of boiler is larger, if do not adopt advanced control mode, then the requirement of dispatching of power netwoks to unit AGC varying duty performance cannot be met.In varying duty process, in order to make full use of or discharge the accumulation of heat of unit, need boiler combustion rate instruction overshoot to control, namely during application of load same ratio the instruction of coal water increase outside, need specified increase overshoot, varying duty terminate overshoot reset; Contrary in load shedding process, outside the coal water instruction of same ratio reduces, also additionally subtract a bit, after varying duty terminates, overshoot resets more.Conventional overshoot mode is that the change of following load instruction synchronously increases or reduce the corresponding coal water yield, when steam turbine pitch does not participate in regulating, effectively cannot improve the load responding ability of unit.
Summary of the invention
Object of the present invention is exactly provide a kind of overcritical or ultra supercritical unit varying duty overshoot control method to overcome defect that above-mentioned prior art exists, feedwater and the overshoot of coal amount are separately carried out, the overshoot different according to the generation of the condition intelligent of unit before varying duty, realizes the load under turbine high-pressure governing valve sliding pressure operation and control of steam temperature better.
Object of the present invention can be achieved through the following technical solutions:
A kind of overcritical or ultra supercritical unit varying duty overshoot control method, it is characterized in that, feedwater and the overshoot of coal amount are separately carried out by the method, and produce different overshoot according to the condition intelligent of unit before varying duty, and described control method specifically comprises the following steps:
1) load instruction and actual load are compared, judge whether its deviation is greater than the first definite value, trigger feedwater overshoot if yes, overshoot adopts grading control;
2) actual intermediate point enthalpy and enthalpy setting value are compared, judge whether its deviation is greater than the second definite value, if yes, trigger the overshoot of coal amount, overshoot adopts grading control.
Described step 1) be specially:
11) load instruction and actual load are compared, judge whether its deviation is greater than the first definite value, if yes, perform step 12), otherwise continue to perform step 11);
12) judge whether this deviation is positive number, if yes, perform step 13), otherwise perform step 14);
13) trigger first time forward feedwater overshoot, if deviation continues to strengthen, trigger second time forward feedwater overshoot, until deviation reduces, after deviation reduces, carry out overshoot and progressively reset;
14) trigger first time negative sense feedwater overshoot, if deviation continues to reduce, trigger second time negative sense feedwater overshoot, until deviation increases, after deviation increases, carry out overshoot and progressively reset.
Described feedwater overshoot resets from overshoot and adopts different speed.
Described step 2) be specially:
21) actual intermediate point enthalpy and enthalpy setting value are compared, judge whether its deviation is greater than the second definite value, if yes, perform step 22), otherwise continue to perform step 21);
22) judge whether this deviation is positive number, if yes, perform step 23), otherwise perform step 24);
23) trigger first time negative sense coal amount overshoot, if deviation continues to strengthen, trigger the overshoot of second time negative sense coal amount, until deviation reduces, after deviation reduces, carry out overshoot and progressively reset;
24) trigger first time forward coal amount overshoot, if deviation continues to reduce, trigger the overshoot of second time forward coal amount, until deviation increases, after deviation increases, carry out overshoot and progressively reset.
Described coal amount overshoot resets from overshoot and adopts different speed.
Described actual intermediate point enthalpy is steam-water separator outlet enthalpy.
Compared with prior art, after the present invention adopts above-mentioned overshoot technology, even if when steam turbine pitch standard-sized sheet does not participate in Load Regulation, unit actual load also can substantially be followed the change of AGC load instruction and change, reach the check requirements of dispatching of power netwoks to AGC varying duty performance, while realizing power unit in economic operation, also can meet the performance requirement of electrical network to unit varying duty.
Accompanying drawing explanation
Fig. 1 is application of load of the present invention feedwater forward overshoot schematic diagram;
Fig. 2 is enthalpy of the present invention higher coal amount negative sense overshoot schematic diagram;
Fig. 3 is feedwater coal amount overshoot introducing position view;
Fig. 4 is the curve map of unit AGC instruction under overshoot of the present invention, load instruction and actual load.
Detailed description of the invention
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
Embodiment
In order to reduce the restriction loss of turbine high-pressure governing valve, improve unit operation economy, have employed the mode of turbine high-pressure governing valve standard-sized sheet sliding pressure operation, in varying duty process, pitch no longer participates in Load Regulation or Steam Pressure Control of Circulated, thus affects unit varying duty performance.Conventional overshoot mode is that the change of following load instruction synchronously increases or reduce the corresponding coal water yield, when steam turbine pitch does not participate in regulating, effectively cannot improve the load responding ability of unit.For this reason, the invention provides a kind of new varying duty overshoot control mode, make up the decline due to pitch standard-sized sheet afterload changing capability.
Overcritical or extra-supercritical unit is after entering DC state, evaporation capacity equals feedwater flow, although steam turbine pitch standard-sized sheet cannot change evaporation capacity by pitch during varying duty, evaporation capacity can be caused to change by changing feedwater flow, thus reach the effect of Rapid Variable Design unit load.Therefore the present invention devises a kind of new overshoot method: namely when load instruction and actual load deviation are greater than certain value, trigger feedwater overshoot, overshoot adopts grading control, and relevant with load deviation.When load instruction is greater than actual load, need application of load, triggering feedwater overshoot increases a certain amount of feedwater, thus corresponding increase evaporation capacity, unit load is increased, and when load deviation reduces, overshoot progressively resets; When load instruction is less than actual load, need load shedding, trigger the negative overshoot of feedwater and reduce a certain amount of feedwater, thus corresponding minimizing evaporation capacity, unit load is reduced, and when load deviation reduces, overshoot progressively resets.
The overshoot of coal amount is not simple according to load instruction or load deviation, but adopt the intermediate point enthalpy (steam-water separator outlet enthalpy) representing coal-water ratio relation and the change of boiler heat storage amount, according to the variation tendency of enthalpy with trigger with the deviation size of setting value, like this can the intelligentized accumulation of heat situation according to boiler before varying duty, come reasonable supplement or release accumulation of heat.During when the rising of intermediate point enthalpy and higher than setting value, trigger and subtract the overshoot of coal amount, overshoot adopts classification process, overshoot reset after enthalpy falls after rise; During when the decline of intermediate point enthalpy and lower than setting value, trigger the overshoot of coal amount, after enthalpy rises, overshoot resets.
After adopting such overshoot mode, even if when steam turbine pitch standard-sized sheet does not participate in Load Regulation, unit actual load also can substantially be followed the change of AGC load instruction and change, reach the check requirements of dispatching of power netwoks to AGC varying duty performance, while realizing power unit in economic operation, also can meet the performance requirement of electrical network to unit varying duty.
In unit DCS control system, carry out Logical Configuration, realize above-mentioned controlling functions, specific embodiments is shown in Fig. 1-3, and implementation result is shown in certain AGC testing load change curve (Fig. 4)
Fig. 1 represents feedwater overshoot during application of load.After load instruction is higher than actual load certain value, trigger a certain amount of forward feedwater overshoot, after this deviation reduces, overshoot is replied, and overshoot triggers and adopts different speed with replying.Overshoot adopts classification process, namely when load deviation continues to strengthen, original overshoot triggers new overshoot again, and deviation reduces rear secondary overshoot to some extent and resets.Feedwater overshoot during load shedding is similar, just becomes negative sense overshoot and reduces confluent, feedwater overshoot during final resulting load instruction change.
Coal-fired overshoot when Fig. 2 represents that enthalpy is higher.After actual enthalpy is higher than enthalpy setting value certain value, triggers the overshoot of a certain amount of negative sense coal amount, namely reduce a certain amount of fire coal, after enthalpy deviation reduces, overshoot is replied, and overshoot triggers and adopts different speed with replying.Overshoot adopts classification process, namely when enthalpy deviation continues to strengthen, original overshoot triggers new overshoot again, and deviation reduces rear secondary overshoot to some extent and resets.Coal amount overshoot when enthalpy is on the low side is similar, just becomes forward overshoot and increases Coal-fired capacity, coal amount overshoot during final synthesis enthalpy change.
Fig. 3 represents feedwater, position is introduced in the overshoot of coal amount.Generate boiler master instruction by unit load instruction, then generate the master instruction of feedwater, coal amount through feed water function and boiler master one coal flow function of boiler master one respectively, superpose overshoot respectively and form final feedwater and the instruction of coal amount.
Fig. 4 represents under this overshoot mode, unit AGC varying duty curve, analytic curve is known, when the standard-sized sheet sliding pressure operation of steam turbine high-pressure governing valve, unit actual load can follow AGC instruction change, and speed reaches 1.5% rated load per minute of dispatching of power netwoks requirement.
Claims (5)
1. an overcritical or ultra supercritical unit varying duty overshoot control method, it is characterized in that, feedwater and the overshoot of coal amount are separately carried out by the method, and produce different overshoot according to the condition intelligent of unit before varying duty, and described control method specifically comprises the following steps:
1) load instruction and actual load are compared, judge whether its deviation is greater than the first definite value, trigger feedwater overshoot if yes, overshoot adopts grading control;
2) actual intermediate point enthalpy and enthalpy setting value are compared, judge whether its deviation is greater than the second definite value, if yes, trigger the overshoot of coal amount, overshoot adopts grading control.
2. the overcritical or ultra supercritical unit varying duty overshoot control method of one according to claim 1, is characterized in that, described step 1) be specially:
11) load instruction and actual load are compared, judge whether its deviation is greater than the first definite value, if yes, perform step 12), otherwise continue to perform step 11);
12) judge whether this deviation is positive number, if yes, perform step 13), otherwise perform step 14);
13) trigger first time forward feedwater overshoot, if deviation continues to strengthen, trigger second time forward feedwater overshoot, until deviation reduces, after deviation reduces, carry out overshoot and progressively reset;
14) trigger first time negative sense feedwater overshoot, if deviation continues to reduce, trigger second time negative sense feedwater overshoot, until deviation increases, after deviation increases, carry out overshoot and progressively reset.
3. the overcritical or ultra supercritical unit varying duty overshoot control method of one according to claim 2, it is characterized in that, described feedwater overshoot resets from overshoot and adopts different speed.
4. the overcritical or ultra supercritical unit varying duty overshoot control method of one according to claim 1, is characterized in that, described step 2) be specially:
21) actual intermediate point enthalpy and enthalpy setting value are compared, judge whether its deviation is greater than the second definite value, if yes, perform step 22), otherwise continue to perform step 21);
22) judge whether this deviation is positive number, if yes, perform step 23), otherwise perform step 24);
23) trigger first time negative sense coal amount overshoot, if deviation continues to strengthen, trigger the overshoot of second time negative sense coal amount, until deviation reduces, after deviation reduces, carry out overshoot and progressively reset;
24) trigger first time forward coal amount overshoot, if deviation continues to reduce, trigger the overshoot of second time forward coal amount, until deviation increases, after deviation increases, carry out overshoot and progressively reset.
5. the overcritical or ultra supercritical unit varying duty overshoot control method of one according to claim 4, it is characterized in that, described coal amount overshoot resets from overshoot and adopts different speed.
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Cited By (3)
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| CN105465823A (en) * | 2015-12-29 | 2016-04-06 | 广东电网有限责任公司电力科学研究院 | Control method and system for preventing fuel-water ratio of once-through boiler of heat-engine plant from imbalance |
| CN107228380A (en) * | 2017-05-19 | 2017-10-03 | 中国神华能源股份有限公司 | The method and system for determining boiler heating parameters are instructed by generated output |
| CN111649313A (en) * | 2020-06-16 | 2020-09-11 | 上海明华电力科技有限公司 | Control method for inhibiting heat transfer deterioration of water-cooled wall of vertical tube coil of supercritical boiler |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105465823A (en) * | 2015-12-29 | 2016-04-06 | 广东电网有限责任公司电力科学研究院 | Control method and system for preventing fuel-water ratio of once-through boiler of heat-engine plant from imbalance |
| CN105465823B (en) * | 2015-12-29 | 2017-12-12 | 广东电网有限责任公司电力科学研究院 | Prevent the control method and system of thermal power plant's direct current cooker Fuel- Water Rate imbalance |
| CN107228380A (en) * | 2017-05-19 | 2017-10-03 | 中国神华能源股份有限公司 | The method and system for determining boiler heating parameters are instructed by generated output |
| CN111649313A (en) * | 2020-06-16 | 2020-09-11 | 上海明华电力科技有限公司 | Control method for inhibiting heat transfer deterioration of water-cooled wall of vertical tube coil of supercritical boiler |
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