Automatic control method for high exhaust pressure of steam turbine under high-low side combined heat supply working condition

Abstract

An automatic control method for high exhaust pressure of a steam turbine under a high-low side combined heat supply working condition relates to the technical field of heat supply units and comprises the following steps: acquiring a first adjusting parameter, a second adjusting parameter, a third adjusting parameter and a high exhaust pressure value; based on the first adjustment parameter, the second adjustment parameter and the third adjustment parameter, generating a first adjustment target, a second adjustment target and a third adjustment target correspondingly; whether the high discharge pressure value obtained in real time exceeds the safety range in the first adjustment target or not is judged; if yes, the opening degree of a middle control valve is adjusted, and the adjusted and controlled high exhaust pressure value meets the corresponding combination of the first adjustment target, the second adjustment target or the third adjustment target under different conditions; if not, continuously monitoring the high discharge pressure value; the method can solve the problem that the high-discharge pressure adjusting result is inaccurate.

Description

Technical Field

[0001] The invention relates to the technical field of heating units, and in particular to a method for automatically controlling high exhaust pressure under high and low bypass combined heating conditions of a steam turbine. Background Art

[0002] In the context of "dual carbon", in order to solve the problem of new energy electricity consumption, thermal power generating units, which account for the largest proportion, need to undertake more peak-shaving tasks, while also taking into account the needs of industry, people's livelihood and heating; especially in winter, heating becomes one of the important tasks. Traditional thermal power generating units have limited heating capacity when operating at low load, and the use of high-low-side combined heating technology can enhance this capacity.

[0003] The turbine high and low bypass combined heating technology adjusts the bypass steam flow to reduce the amount of steam entering the three cylinders of the turbine. In this way, the excess steam can be used for heating without affecting power production, thereby improving the heating capacity of the unit during low-load operation and meeting the heating needs during deep peak-shaving operation.

[0004] When the high and low bypass of the steam turbine are combined for heating, the high exhaust pressure will be reduced, and the blades of the last stage of the high pressure cylinder will be subjected to a greater front-to-rear pressure difference, which will increase the safety risk of blade operation. Therefore, the high exhaust pressure is kept in the safe range value under the corresponding load by adjusting the middle valve or matching the high and low bypass flow, ensuring the safe operation of the unit when the steam turbine is combined for heating;

[0005] Traditionally, the high-discharge pressure is adjusted to a suitable value by adjusting the size of the middle regulating valve based on experience. However, this method is not suitable for workers with insufficient experience. On the other hand, the high-discharge pressure value adjusted based on experience may affect the turbine because there are fewer reference factors.

[0006] The Chinese patent with publication number: CN113266435B discloses a method and device for adjusting the high exhaust pressure by using a medium pressure regulating valve. It only determines whether the high exhaust pressure exceeds the upper limit or is lower than the lower limit to decide whether to open or close the medium regulating valve to adjust the high exhaust pressure value. After adjusting the medium regulating valve, it is determined again whether the high exhaust pressure exceeds the upper limit or is lower than the lower limit to determine the adjustment degree of the high exhaust pressure. Therefore, the accuracy of the high exhaust pressure judgment of this method is poor; and when adjusting the high exhaust pressure, the steps adopted by this method are relatively cumbersome, because the adjustment process of the high exhaust pressure will also affect the operation of the steam turbine, so the cumbersome operation process will affect the working effect of the steam turbine.

[0007] Therefore, we propose a method that can accurately control the high exhaust pressure adjustment. Summary of the invention

[0008] The object of the present invention is to provide a method for automatically controlling high exhaust pressure under high and low bypass combined heating conditions of a steam turbine, which is used to solve the problem of inaccurate high exhaust pressure adjustment results.

[0009] The present invention is achieved through the following technical solutions:

[0010] A method for automatically controlling high exhaust pressure under high and low bypass combined heating conditions of a steam turbine comprises:

[0011] Obtaining a first adjustment parameter, a second adjustment parameter, a third adjustment parameter and a high exhaust pressure value;

[0012] Based on the first adjustment parameter, the second adjustment parameter and the third adjustment parameter, respectively generate a corresponding first adjustment target, a second adjustment target and a third adjustment target;

[0013] Determine whether the high-discharge pressure value obtained in real time exceeds the safety range of the first adjustment target;

[0014] If it exceeds, the opening of the intermediate regulating valve is adjusted, and the adjusted high exhaust pressure value is made to meet the corresponding combination of the first regulating target, the second regulating target or the third regulating target under different conditions;

[0015] If not exceeded, continue to monitor the high discharge pressure value.

[0016] Furthermore, the first adjustment parameter includes the pressure after the adjustment stage, the low alarm parameter and the high alarm parameter, and the first adjustment target is the safety range control function. The expression of the safety range control function f(x) is:

[0017] f(x)=mX+b;

[0018] Where X is the pressure after the regulating stage, m is the slope, and b is the intercept;

[0019] The safety range is [f(x)-α, f(x)+β], where α and β are low alarm parameters and high alarm parameters respectively.

[0020] Furthermore, the second regulating parameter includes the high bypass inlet steam flow H a , high bypass cooling water flow H b and low bypass inlet steam flow H c , the second regulation target is the matching relationship between high and low bypass steam flow rates, and the expression of the matching relationship is:

[0021] H a +H b =H c .

[0022] Furthermore, the third adjustment parameter includes the pressure after the adjustment stage, and the third adjustment target is the high-pressure cylinder pressure ratio U, which is specifically expressed as:

[0023]

[0024] Among them, X is the pressure after the regulating stage, and Y is the high discharge pressure value.

[0025] Furthermore, when the rate of change of the load of the unit is less than 10%, the high exhaust pressure value after regulation is within the safety range [f(x)-α, f(x)+β] of the safety range control function.

[0026] Furthermore, when the unit is in a relatively stable operating state, the high bypass inlet steam flow H affected by the regulated high exhaust pressure is a , high bypass cooling water flow H b and low bypass inlet steam flow H c , the high and low bypass steam flow matching relationship needs to be met.

[0027] Furthermore, when the turbine is in the range of 70% to 40% electrical load and the boiler load is in the range of 70% to 60%, the high-pressure cylinder pressure ratio is calculated to be in the range of (3.5, 4.5) by using the regulated high exhaust pressure value.

[0028] Furthermore, when the load variation of the unit is greater than 20% or the heating demand changes, the regulated high exhaust pressure value needs to meet the first regulation target and the second regulation target at the same time.

[0029] Furthermore, when the turbine is in the range of 70% to 40% electrical load, the boiler load is in the range of 70% to 60%, and the load variation of the unit is less than 10%, the regulated high exhaust pressure value needs to meet both the first regulation target and the third regulation target.

[0030] Furthermore, when the load or heating demand needs to be adjusted frequently, the regulated high discharge pressure value needs to meet the second regulation target and the third regulation target at the same time.

[0031] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0032] The present invention discloses a high-discharge pressure automatic control method under high-low bypass combined heating conditions of a steam turbine, which can effectively improve the accuracy of the regulated high-discharge pressure value by utilizing a combination of multiple adjustment targets, thereby ensuring that the unit can operate safely when the steam turbine is in high-low bypass combined heating.

[0033] In addition, by implementing different control targets for the high exhaust pressure value under different conditions of the steam turbine, the accuracy of the controlled high exhaust pressure value can be further improved, effectively taking into account the power supply and heating work of the thermal power generating unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1It is a schematic diagram of the method flow of the present invention;

[0035] Figure 2 It is a schematic diagram of the system structure in the present invention;

[0036] Figure 3 It is a schematic diagram of the structure of the electronic device in the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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 part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0041] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Example 1

[0043] As attached Figure 1 The method for automatically controlling high exhaust pressure under high and low bypass combined heating conditions of a steam turbine is shown, comprising:

[0044] Obtaining a first adjustment parameter, a second adjustment parameter, a third adjustment parameter and a high exhaust pressure value;

[0045] Based on the first adjustment parameter, the second adjustment parameter and the third adjustment parameter, respectively generate a corresponding first adjustment target, a second adjustment target and a third adjustment target;

[0046] The high exhaust pressure value is a parameter value that needs to be regulated, and the first regulation target is calculated based on the first regulation parameter, the second regulation target is calculated based on the second regulation parameter, and the third regulation target is calculated based on the third regulation parameter, and by making the regulated high exhaust pressure value directly or indirectly meet the requirements of the first regulation target, the second regulation target and the third regulation target, it is ensured that the regulated high exhaust pressure value can enable the thermal power generating set to maintain good heating and power supply at the same time;

[0047] In addition, the first adjustment parameter includes the pressure after the adjustment stage, the low alarm parameter and the high alarm parameter, and the first adjustment target is the safety range control function. The expression of the safety range control function f(x) is:

[0048] f(x)=mX+b;

[0049] Where X is the pressure after the regulating stage, m is the slope, and b is the intercept;

[0050] The safety range is [f(x)-α, f(x)+β], where α and β are low alarm parameters and high alarm parameters respectively; that is, the first adjustment target is to determine a safety control range, and to ensure that the high exhaust pressure value after adjustment is within the safety control range, so as to meet the requirements of the thermal power generating unit;

[0051] In addition, tests were conducted in the range of 70% to 40% electrical load and 70% to 60% boiler load for a supercritical 350MW steam turbine, and the results showed that the values ​​of α and β were 0.2 and 0.4, respectively, that is, the safety range is [f(x)-0.2,f(x)+0.4].

[0052] In addition, the second adjustment parameter includes the high bypass inlet steam flow H a , high bypass cooling water flow H b and low bypass inlet steam flow H c , the second regulation target is the matching relationship between high and low bypass steam flow rates, and the expression of the matching relationship is:

[0053] H a +H b =H c ;

[0054] The second regulation target is used to indirectly calculate the control result of the high exhaust pressure value. a , high bypass cooling water flow H b and low bypass inlet steam flow H c , will be affected by the high-discharge pressure value, and the three parameters in the second adjustment parameter can be calculated by the flow meter. In the process of adjusting the high-discharge pressure value, the three parameters in the second adjustment parameter are monitored in real time, and judged according to the expression. When the expression is established, the adjustment of the high-discharge pressure value can be stopped, indicating that the high-discharge pressure value has been adjusted in place;

[0055] It should be noted that the regulation of the high exhaust pressure value is achieved by controlling the opening of the middle regulating valve;

[0056] As required, the third adjustment parameter includes the pressure after the adjustment stage, and the third adjustment target is the high-pressure cylinder pressure ratio U, which is specifically expressed as:

[0057]

[0058] Among them, X is the pressure after the regulating stage, and Y is the high discharge pressure value;

[0059] It should be noted that the value of the high-pressure cylinder pressure ratio U is also obtained by testing in the range of 70% to 40% of the supercritical 350MW steam turbine electrical load and 70% to 60% of the boiler load. Because the test is basically a full-load operation of the generator set, the result obtained is relatively accurate, specifically (3.5, 4.5).

[0060] Determine whether the high-discharge pressure value obtained in real time exceeds the safety range of the first adjustment target;

[0061] If it exceeds, the opening of the middle regulating valve is adjusted, and the high exhaust pressure value after adjustment is made to meet the corresponding combination of the first adjustment target, the second adjustment target or the third adjustment target under different conditions, wherein the specific combination form may be any one of the first adjustment target, the second adjustment target or the third adjustment target alone, or a combination of the first adjustment target and the second adjustment target, a combination of the first adjustment target and the third adjustment target, or a combination of the third adjustment target and the second adjustment target, or a combination of the first adjustment target, the second adjustment target and the third adjustment target; it should be noted that the specific combination form selected will be determined according to the operation of the thermal power generating unit;

[0062] If it does not exceed the limit, the high-discharge pressure value will continue to be monitored, and there is no need to adjust the opening of the middle regulating valve at this time, and the current high-discharge pressure value will be maintained.

[0063] Example 2

[0064] When the load change rate of the unit is less than 10%, the high discharge pressure value after regulation only meets the first regulation target, specifically: the high discharge pressure value after regulation is within the safety range [f(x)-α, f(x)+β] of the safety range control function, and according to the test in the range of 70% to 40% of the supercritical 350MW steam turbine electrical load and 70% to 60% of the boiler load, the values ​​of α and β are 0.2 and 0.4 respectively, that is, the safety range is [f(x)-0.2, f(x)+0.4];

[0065] In addition, since the expression of the first regulation target, the safety range control function f(x), is a linear equation, the specific expression of the safety range control function f(x) can be obtained according to the given two sets of data of the pressure after the regulation stage (MPa) X and the high-discharge pressure value (MPa) during implementation; if the two sets of data of the pressure after the regulation stage (MPa) X and the high-discharge pressure value (MPa) are respectively: (11.19, 2.8) and (15.96, 3.59), then

[0066] f(x)=0.17X+0.95;

[0067] The safety range can be obtained by substituting the post-adjustment pressure (MPa) X obtained according to the high-discharge pressure value after adjustment into the expression, and it can be determined whether the high-discharge pressure value after adjustment is within the safety range.

[0068] When the unit is in a relatively stable operating state, the adjusted high exhaust pressure value only needs to meet the second regulation target, that is, the high bypass inlet steam flow H affected by the adjusted high exhaust pressure. a , high bypass cooling water flow H b and low bypass inlet steam flow H c , the high and low bypass steam flow matching relationship needs to be met.

[0069] When the turbine is in the range of 70% to 40% electrical load and the boiler load is in the range of 70% to 60%, the regulated high exhaust pressure value only needs to meet the third regulation target, that is, the regulated high exhaust pressure value is used to make the calculated high-pressure cylinder pressure ratio be between (3.5, 4.5).

[0070] Example 3

[0071] When the load change of the unit is greater than 20% or the heating demand changes, the high exhaust pressure value after regulation needs to meet the first regulation target and the second regulation target at the same time; that is, the high exhaust pressure value after regulation must be within the safety range, and the high bypass inlet steam flow H affected by the high exhaust pressure after regulation a , high bypass cooling water flow H b and low bypass inlet steam flow H c, and the matching relationship between high and low bypass steam flows needs to be met; because the combination of the two methods can provide more precise control when the load changes rapidly.

[0072] When the turbine is in the range of 70% to 40% electrical load, the boiler load is in the range of 70% to 60%, and the load change of the unit is less than 10%, the regulated high exhaust pressure value needs to meet the first regulation target and the third regulation target at the same time; that is, the regulated high exhaust pressure value must be within the corresponding safety range, and the high-pressure cylinder pressure ratio calculated according to the regulated high exhaust pressure must be within (3.5, 4.5); because this ensures that the unit can maintain safe and efficient operation even under complex and changeable operating conditions.

[0073] In addition, when the load or heating demand needs to be adjusted frequently, the high exhaust pressure value after regulation needs to meet both the second regulation target and the third regulation target; that is, the high bypass inlet steam flow H affected by the high exhaust pressure after regulation needs to be a , high bypass cooling water flow H b and low bypass inlet steam flow H c , satisfying the matching relationship between high and low bypass steam flows, and ensuring that the high-pressure cylinder pressure ratio calculated based on the regulated high exhaust pressure is within (3.5, 4.5); this ensures that the heating supply of the generator meets the requirements.

[0074] Example 4

[0075] When the unit faces extreme operating conditions, such as deep peak regulation, rapid start and stop, or other situations that may cause drastic fluctuations in the high exhaust pressure, it is necessary to meet three control targets at the same time; that is, the high exhaust pressure value after regulation is within the safe range, and the high bypass inlet steam flow H affected by the high exhaust pressure after regulation a , high bypass cooling water flow H b and low bypass inlet steam flow H c , satisfying the matching relationship between high and low bypass steam flows, and the high-pressure cylinder pressure ratio calculated according to the regulated high exhaust pressure is in the range of (3.5, 4.5); this can maximize the safety and stability of the unit, especially at critical moments that are very sensitive to the high exhaust pressure.

[0076] Example 5

[0077] As attached Figure 2 The high exhaust pressure automatic control system under the high and low bypass combined heating working condition of the steam turbine shown includes a parameter acquisition module, a first calculation module, a second calculation module, a third calculation module, a judgment module and a control module;

[0078] The parameter acquisition module is used to acquire the first adjustment parameter, the second adjustment parameter, the third adjustment parameter and the high exhaust pressure value;

[0079] The first calculation module is used to calculate a first control target according to the first adjustment parameter;

[0080] The second calculation module is used to calculate a second control target according to the second adjustment parameter;

[0081] The third calculation module is used to calculate a third control target according to the third adjustment parameter;

[0082] The judging module is used to judge whether the high-discharge pressure value acquired in real time exceeds the safety range of the first adjustment target;

[0083] The control module is used to change the opening of the middle control valve according to the result of the judgment module, and call the high exhaust pressure value in the parameter acquisition module in combination with the different conditions of the generator set, and make the high exhaust pressure value meet the corresponding combination of the first calculation module result, the second calculation module result or the third calculation module result.

[0084] Example 6

[0085] As attached Figure 3 An electronic device as shown, characterized in that it includes:

[0086] Processor, memory, communication interface;

[0087] The memory is used to store executable instructions of the processor;

[0088] Wherein, the processor is configured to execute the above-mentioned high exhaust pressure automatic control method under the high and low bypass combined heating conditions of the steam turbine by executing the executable instructions.

[0089] A readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the high exhaust pressure automatic control method under the above-mentioned steam turbine high and low bypass combined heating conditions is implemented.

[0090] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for automatically controlling high exhaust pressure under high and low bypass combined heating conditions of a steam turbine, characterized in that: include: Obtaining a first adjustment parameter, a second adjustment parameter, a third adjustment parameter and a high exhaust pressure value; Based on the first adjustment parameter, the second adjustment parameter and the third adjustment parameter, respectively generate a corresponding first adjustment target, a second adjustment target and a third adjustment target; Determine whether the high-discharge pressure value obtained in real time exceeds the safety range of the first adjustment target; If it exceeds, the opening of the intermediate regulating valve is adjusted, and the adjusted high exhaust pressure value is made to meet the corresponding combination of the first regulating target, the second regulating target or the third regulating target under different conditions; If not exceeded, continue to monitor the high discharge pressure value.

2. The high exhaust pressure automatic control method under the high and low bypass combined heating condition of the steam turbine according to claim 1 is characterized in that: The first adjustment parameter includes the pressure after the adjustment stage, the low alarm parameter and the high alarm parameter. The first adjustment target is the safety range control function. The expression of the safety range control function f(x) is: f(x)=mX+b; Where X is the pressure after the regulating stage, m is the slope, and b is the intercept; The safety range is [f(x)-α, f(x)+β], where α and β are low alarm parameters and high alarm parameters respectively.

3. The high exhaust pressure automatic control method under the high and low bypass combined heating condition of the steam turbine according to claim 2 is characterized by: The second adjustment parameter includes the high bypass inlet steam flow H a , high bypass cooling water flow H b and low bypass inlet steam flow H c , the second regulation target is the matching relationship between high and low bypass steam flow rates, and the expression of the matching relationship is: H a +H b =H c 。 4. The high exhaust pressure automatic control method under high and low bypass combined heating conditions of a steam turbine according to claim 3 is characterized in that: The third adjustment parameter includes the pressure after the adjustment stage, and the third adjustment target is the high-pressure cylinder pressure ratio U, which is specifically expressed as: Among them, X is the pressure after the regulating stage, and Y is the high discharge pressure value.

5. The high exhaust pressure automatic control method under the high and low bypass combined heating condition of the steam turbine according to claim 4 is characterized in that: When the rate of change of the unit's load is less than 10%, the high exhaust pressure value after regulation is within the safety range [f(x)-α, f(x)+β] of the safety range control function.

6. The high exhaust pressure automatic control method under the high and low bypass combined heating condition of the steam turbine according to claim 4 is characterized in that: When the unit is in a relatively stable operating state, the high bypass inlet steam flow rate H affected by the regulated high exhaust pressure a , high bypass cooling water flow H b and low bypass inlet steam flow H c , the high and low bypass steam flow matching relationship needs to be met.

7. The high exhaust pressure automatic control method under high and low bypass combined heating conditions of a steam turbine according to claim 4 is characterized in that: When the turbine is in the range of 70% to 40% electrical load and the boiler load is in the range of 70% to 60%, the high-pressure cylinder pressure ratio is calculated to be in the range of (3.5, 4.5) by using the regulated high-discharge pressure value.

8. The high exhaust pressure automatic control method under high and low bypass combined heating conditions of a steam turbine according to claim 4 is characterized in that: When the load variation of the unit is greater than 20% or the heating demand changes, the adjusted high exhaust pressure value needs to meet the first adjustment target and the second adjustment target at the same time.

9. The high exhaust pressure automatic control method under high and low bypass combined heating conditions of a steam turbine according to claim 4 is characterized in that: When the turbine is in the electric load range of 70% to 40%, the boiler load is in the range of 70% to 60%, and the load variation of the unit is less than 10%, the regulated high exhaust pressure value needs to meet both the first and third regulation targets.

10. The high exhaust pressure automatic control method under high and low bypass combined heating conditions of a steam turbine according to claim 4, characterized in that: When the load or heating demand needs to be adjusted frequently, the regulated high discharge pressure value needs to meet the second regulation target and the third regulation target at the same time.

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