Thermal power unit reheat steam outlet temperature control method based on dynamic parameter optimization

Abstract

The scheme discloses a thermal power unit reheat steam outlet temperature control method based on dynamic parameter optimization, which directly controls the low-temperature reheater outlet temperature by taking the reheater desuperheating water guide front temperature set value as the flue gas damper dynamic set value baseline, greatly reduces the hysteresis of the reheat flue gas damper control object, and can effectively reduce the action frequency of the desuperheating water. Meanwhile, the reheating flue gas damper set value is dynamically corrected through the deviation between the high-temperature reheater outlet temperature set value and the actual value, the advanced adjustment is carried out before the reheater desuperheating water acts, the closed loop is optimized, and the response speed can be further improved. Therefore, the scheme can not only avoid the influence of frequent and large desuperheating water input on the thermal efficiency of the boiler, but also improve the economy of the unit, effectively reduce the oscillation phenomenon of over-temperature and under-temperature, improve the automatic input rate of the flue gas damper, and reduce the labor intensity of the operator.

Description

Technical Field

[0001] This invention belongs to the field of automatic control technology, and in particular relates to a method for controlling the reheat steam outlet temperature of ultra-supercritical thermal power units based on dynamic parameter optimization. Background Technology

[0002] In current ultra-supercritical thermal power units, a reheat system is typically designed to improve the thermal efficiency of the operating unit and the utilization rate of pressurized steam. This system further heats the low-pressure steam that has already performed work, enabling the secondary utilization of the steam. Both excessively high and low reheat steam temperatures can affect the safety and economy of the power plant. Therefore, controlling the reheat steam temperature of thermal power units is particularly important and must be efficiently regulated within a safe range.

[0003] The steam flows from the low-temperature reheater 4 to the high-temperature reheater 3. The steam coming out of the high-temperature reheater 3 is the reheated steam after reheating treatment. We need to control this reheated steam within a certain range to ensure safety.

[0004] like Figure 1 As shown, pulverized coal is burned in the π-shaped furnace 7, and the resulting hot flue gas flows in the following direction: screen-type superheater 1 -- high-temperature superheater 2 -- high-temperature reheater 3 -- low-temperature reheater 4 and low-temperature superheater 5 + economizer 6 arranged in parallel at the tail flue, releasing heat to these components. The reheat flue gas baffles A1 and B1 and the superheat flue gas baffles A2 and B2 at the tail flue control the flue gas volume distribution in the tail flue by changing their opening degrees, thereby controlling the heat absorption of the steam flowing through the low-temperature reheater 4. Reheat flue gas baffles A1 and A2 are grouped together, and reheat flue gas baffles B1 and B2 are grouped together. The opening degrees of the reheat flue gas baffles and superheat flue gas baffles within each group are inversely related.

[0005] Currently, the common method for regulating reheat steam outlet temperature in ultra-supercritical units is to target the high-temperature reheater outlet temperature by adjusting the opening of the flue gas dampers at the outlets of the low-temperature reheater 4 and economizer 6 to regulate the flow of flue gas, thereby achieving the goal of regulating the high-temperature reheater outlet temperature. This employs conventional PID control. When the high-temperature reheater outlet temperature exceeds the limit and emergency intervention is required, control is achieved through reheater desuperheating water regulation. However, because the flue gas dampers regulate the low-temperature reheater, there is a significant lag in controlling the reheat steam temperature after passing through the high-temperature reheater. This results in insensitive steam temperature regulation and a high risk of over-regulation. Although desuperheating water control is available, the high lag of the flue gas dampers makes simple damper control prone to significant temperature over- or under-regulation. If the temperature is too high, a large amount of desuperheating water is required. Excessive desuperheating water or excessively low steam temperature will reduce the unit's cycle efficiency and economic efficiency. Therefore, the current control method has two problems. First, the frequent and large-scale input of desuperheating water will have a significant impact on the thermal efficiency of the unit and reduce its economic efficiency. Second, the reheat steam outlet temperature is prone to repeated overheating and underheating fluctuations, making it difficult to ensure that the reheat steam temperature is within the required range and affecting the safety of the unit. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing a method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions:

[0008] A method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization includes:

[0009] S1. Obtain the actual value of the high-temperature reheater outlet temperature;

[0010] S2. The first control logic generates a value based on the actual value of the high temperature reheater outlet temperature and the set value of the high temperature reheater outlet temperature, such that the actual value of the high temperature reheater outlet temperature is equal to the set value of the high temperature reheater outlet temperature or the set value of the desuperheating water inlet temperature within its allowable deviation range.

[0011] S4. Determine the low-temperature reheater outlet temperature setting value based on the desuperheating water inlet temperature setting value;

[0012] S5. Compare the actual value of the low temperature reheater outlet temperature with the set value of the low temperature reheater outlet temperature, and adjust the flue gas damper through the second control logic so that the actual value of the low temperature reheater outlet temperature continuously approaches the set value of the low temperature reheater outlet temperature.

[0013] S6. The first control logic continuously adjusts the desuperheating water valve of the reheater based on the change in the actual value of the low temperature reheater outlet temperature and the set value of the desuperheating water inlet temperature, so that the actual value of the high temperature reheater outlet temperature is equal to the set value of the high temperature reheater outlet temperature or within its allowable deviation range.

[0014] S7. Repeat steps S5-S6 until the desuperheating water valve is completely closed;

[0015] When the actual value of the high-temperature reheater outlet temperature exceeds the allowable deviation range of the high-temperature reheater outlet temperature setpoint, repeat steps S1-S7.

[0016] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, step S3 is included between steps S2 and S4:

[0017] The actual value of the low temperature reheater outlet temperature is obtained at this time. The first control logic adjusts the reheater desuperheating water valve according to the actual value of the low temperature reheater outlet temperature and the set value of the desuperheating water inlet temperature, so that the actual value of the high temperature reheater outlet temperature is equal to the set value of the high temperature reheater outlet temperature or within its allowable deviation range.

[0018] Step S6 is as follows: The first control logic continuously adjusts the desuperheating water valve of the reheater based on the change in the actual value of the low-temperature reheater outlet temperature and the newly generated desuperheating water inlet temperature setpoint, so that the actual value of the high-temperature reheater outlet temperature is equal to the high-temperature reheater outlet temperature setpoint or within its allowable deviation range; and Step S7 is as follows: Steps S4-S6 are repeated continuously until the desuperheating water valve is completely closed and the actual value of the high-temperature reheater outlet temperature is equal to the high-temperature reheater outlet temperature setpoint or within its allowable deviation range.

[0019] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, in step S3, the setpoint of the desuperheating water inlet temperature is used as the setpoint of the low-temperature reheater outlet temperature.

[0020] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, the method prior to step S3 also includes:

[0021] Using the deviation correction function f2(x), the setpoint of the low temperature reheater outlet temperature is advancedly corrected based on the deviation between the actual value of the high temperature reheater outlet temperature and the setpoint of the high temperature reheater outlet temperature.

[0022] In step S3, the advance correction result is superimposed with the desuperheating water inlet temperature setpoint as the low-temperature reheater outlet temperature setpoint.

[0023] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, in step S3, the set value of the desuperheating water inlet temperature is superimposed with the bias value set by the user as the set value of the low-temperature reheater outlet temperature.

[0024] Alternatively, in step S3, the advanced correction result, the desuperheating water inlet temperature setpoint, and the user-set bias value are superimposed as the low-temperature reheater outlet temperature setpoint.

[0025] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, before step S2, it is first determined whether the desuperheating water control is in automatic mode. If so, the high-temperature reheater outlet temperature setpoint itself is directly taken; otherwise, an adaptive setpoint is determined according to the load and the adaptive setpoint is used as the high-temperature reheater outlet temperature setpoint.

[0026] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, before step S4, it is first determined whether the flue gas damper is in automatic mode. If so, the subsequent steps are executed; otherwise, the second control logic does not take effect.

[0027] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, both the first control logic and the second control logic are PID control logic.

[0028] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, the system has different second control logics pre-stored according to different load ranges. In step S5, the corresponding second control logic is adaptively selected according to the current load.

[0029] In the above-mentioned method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization, the outlet of the low-temperature reheater on side A is connected to the inlet of the high-temperature reheater on side B, and the outlet of the low-temperature reheater on side B is connected to the inlet of the high-temperature reheater on side A, so that steam flows crosswise between side A and side B.

[0030] A reheat steam outlet temperature control system for thermal power units based on dynamic parameter optimization is provided to execute the aforementioned reheat steam outlet temperature control method for thermal power units based on dynamic parameter optimization.

[0031] The advantages of this invention are as follows: Unlike traditional flue gas damper control of reheat steam outlet temperature (i.e., the actual value of the high-temperature reheater outlet temperature), which suffers from significant lag, this solution uses the reheater desuperheating water preheating temperature setpoint as the benchmark for the flue gas damper's dynamic setpoint, directly controlling the low-temperature reheater outlet temperature. This significantly reduces the lag of the reheat flue gas damper's controlled object and effectively decreases the frequency of desuperheating water operation. Simultaneously, the deviation between the high-temperature reheater outlet temperature setpoint and the actual value dynamically corrects the reheat flue gas damper setpoint, performing pre-emptive adjustment before the reheater desuperheating water operates, optimizing the closed loop and further improving response speed. Therefore, this solution avoids the impact of frequent and large-scale desuperheating water input on boiler thermal efficiency, improves unit economy, effectively reduces overheating and underheating fluctuations, increases the automatic operation rate of the flue gas damper, and reduces the workload of operators. Attached Figure Description

[0032] Figure 1 This is a diagram illustrating the flow direction of flue gas in the furnace of an ultra-supercritical unit.

[0033] Figure 2 This is a control flowchart of the ultra-supercritical thermal power unit with dynamic parameter optimization according to the present invention;

[0034] Figure 3 This is a schematic diagram of the dynamic parameter optimization logic of the reheater baffle of an ultra-supercritical thermal power unit according to the present invention.

[0035] Figure 4 This is the interface diagram of the dynamic parameter optimization of the reheater baffle control and conventional control logic of the ultra-supercritical thermal power unit according to the present invention;

[0036] Figure 5 This is a diagram illustrating the application of the optimized control of reheater baffles in ultra-supercritical thermal power units in the 400MW-900MW load range of this invention.

[0037] Figure labels: 1. Screen-type superheater; 2. High-temperature superheater; 3. High-temperature reheater; 4. Low-temperature reheater; 5. Low-temperature superheater; 6. Economizer; 7. Furnace; A1, B1 reheat flue gas dampers; A2, B2 superheat flue gas dampers. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] This embodiment proposes a method and system for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization. Based on the principles of heat transfer, this method ignores the heat absorption and release effects of connecting pipelines. Since they are on the same pipeline, the change in the low-temperature reheater outlet temperature is directly related to the high-temperature reheater outlet temperature only when desuperheating water is not added. First, the desuperheating water guide temperature setpoint is obtained through a first PID control logic. Then, based on the aforementioned heat transfer principles, the high-temperature reheater inlet setpoint, i.e., the desuperheating water guide temperature setpoint, is used as the adjustment benchmark for the low-temperature reheater outlet temperature setpoint. The reheat flue gas damper is adjusted through a second PID control logic to keep the low-temperature reheater outlet temperature within the set range. The adjustment of the flue gas damper continuously replaces the control effect of desuperheating water, thereby minimizing the amount of desuperheating water used while ensuring control accuracy and response speed. The specific implementation method is as follows:

[0040] The actual value of the high temperature reheater outlet temperature is obtained. The first PID control logic generates a value that makes the actual value of the high temperature reheater outlet temperature equal to the high temperature reheater outlet temperature setpoint or the desuperheating water inlet temperature setpoint within its allowable deviation range.

[0041] The actual outlet temperature of the low-temperature reheater is obtained at this time. The first PID control logic adjusts the reheater desuperheating water valve according to the actual outlet temperature of the low-temperature reheater and the setpoint of the desuperheating water inlet temperature, so that the actual outlet temperature of the high-temperature reheater is equal to the setpoint of the high-temperature reheater outlet temperature or within its allowable deviation range. That is, the first PID control logic takes the desuperheating water valve as the controlled object and takes the actual outlet temperature of the high-temperature reheater, the setpoint of the high-temperature reheater outlet temperature, and the actual outlet temperature of the low-temperature reheater as input parameters.

[0042] Subsequently, the set value of the low temperature reheater outlet temperature is determined based on the set value of the desuperheating water inlet temperature. In this embodiment, the set value of the desuperheating water inlet temperature is directly used as the set value of the low temperature reheater outlet temperature.

[0043] The actual value of the low-temperature reheater outlet temperature is compared with the set value of the low-temperature reheater outlet temperature. The flue gas damper is adjusted through the second control logic so that the actual value of the low-temperature reheater outlet temperature continuously approaches the set value of the low-temperature reheater outlet temperature.

[0044] Simultaneously, the first control logic continuously adjusts the reheater desuperheating water valve based on the changes in the actual temperature of the low-temperature reheater outlet and the newly generated desuperheating water inlet temperature setpoint, ensuring that the actual temperature of the high-temperature reheater outlet equals the high-temperature reheater outlet temperature setpoint or falls within its allowable deviation range. Theoretically, under stable external conditions such as load, the desuperheating water inlet temperature setpoint remains constant. In this case, the reheater desuperheating water valve can be continuously adjusted directly based on the initially generated desuperheating water inlet temperature setpoint and the constantly changing actual temperature of the low-temperature reheater outlet.

[0045] However, in practice, the setpoint for the desuperheating water inlet temperature may change during the coordinated adjustment of the flue gas damper and the desuperheating water valve. Furthermore, external factors such as load changes can cause the actual high-temperature reheater outlet temperature to exceed the allowable range, leading to a change in the desuperheating water inlet temperature setpoint. Therefore, the preferred approach is to generate a new desuperheating water inlet temperature setpoint each time, and use this new setpoint and the constantly changing actual low-temperature reheater outlet temperature to adjust the reheater desuperheating water valve. Even if the temperature exceeds the allowable range, this will bring the actual high-temperature reheater outlet temperature back to the setpoint or its allowable deviation range.

[0046] Finally, repeat the above steps until the desuperheating water valve is completely closed and the actual temperature of the high-temperature reheater outlet is equal to the set temperature of the high-temperature reheater outlet or within its allowable deviation range.

[0047] The above scheme requires the desuperheating water and flue gas dampers to be in an automatic adjustment state. However, in actual use, the desuperheating water or flue gas dampers may need to be manually adjusted. This scheme also proposes a solution to address this issue. Furthermore, to achieve better heat transfer, the boiler reheat steam in this scheme flows cross-currently on sides A and B. That is, the reheat steam on side A flows through the low-temperature reheater on side A and then flows to the high-temperature reheater on side B to continue absorbing heat; conversely, the reheat steam on side B flows through the low-temperature reheater on side B and then flows to the high-temperature reheater on side A to continue absorbing heat. For example... Figure 3 As shown, the flow from the low-temperature reheater on side A to the high-temperature reheater on side B is illustrated below, taking into account the possibility of manual adjustment. The flow from side B to side A is similar and will not be repeated.

[0048] S1. First, determine whether the desuperheating water has been removed from the automatic temperature control mode. If so, use the adaptive set value of the load reference temperature; otherwise, directly take the set value of the outlet temperature of the high-temperature reheater on side B.

[0049] When the desuperheating water is withdrawn from automatic regulation and the system is in manual mode, the water valve is no longer adjusted based on the actual temperature of the high-temperature reheater outlet. The desuperheating water side setpoint (i.e., the high-temperature reheater inlet temperature setpoint) tracks the actual temperature. Temperature control via the reheater flue gas damper alone is not as effective as in automatic desuperheating water mode, and over-adjustment is more likely to occur. The higher the load, the more severe the over-adjustment will be. Therefore, the high-temperature reheater outlet temperature setpoint is adaptively generated based on the unit load and operating experience. This setpoint deviates somewhat from the high-temperature reheater outlet temperature setpoint when the desuperheating water is in automatic mode. Generally, it is smaller than the high-temperature reheater outlet temperature setpoint when the desuperheating water is in automatic mode. The higher the load, the closer it is to the high-temperature reheater outlet temperature setpoint when the desuperheating water is in automatic mode. For example, if the high-temperature reheater outlet temperature setpoint when the desuperheating water is in automatic mode is 600℃, the adaptive setpoint may be 597 or 598℃. The system stores adaptive setpoints or set deviations and deviation rates under various unit loads obtained from experience. The adaptive setpoints are then obtained directly based on the unit load, or calculated based on the set deviation / deviation rate and the high-temperature reheater outlet temperature setpoint when desuperheating water is automatically activated.

[0050] S2. Obtain the actual value of the outlet temperature of the high-temperature reheater on side B (referred to as the outlet temperature of the high-temperature reheater on side B in the figure), compare the set value of the outlet temperature of the high-temperature reheater on side B with the actual value of the outlet temperature of the high-temperature reheater on side B, and then control the desuperheating water valve based on the comparison result through the first PID control logic so that the actual value of the outlet temperature of the high-temperature reheater is equal to the set value of the outlet temperature of the high-temperature reheater or within its allowable deviation range. At this time, a desuperheating water set value will be generated, which is also called the desuperheating water inlet temperature set value.

[0051] Then, this pre-heater temperature setpoint is used as the low-temperature reheater outlet temperature setpoint. Control of the desuperheater is gradually transferred to control of the flue gas damper. The second PID control logic adjusts the flue gas damper based on the comparison between the low-temperature reheater outlet temperature setpoint and the actual outlet temperature, ensuring the actual outlet temperature equals the setpoint or falls within its allowable deviation range. Simultaneously, as the flue gas damper adjusts, the actual outlet temperature of the low-temperature reheater continuously approaches the desuperheating water setpoint, thus reducing the desuperheating water adjustment intensity. In a stable state, the desuperheating water valve can be completely closed after adjustment.

[0052] Preferably, to achieve better control, a deviation correction function f2(x) is used to correct the deviation beforehand. The generation rules are set in advance by those skilled in the art based on the characteristics of the unit and the control effect. Taking a 1000MW unit as an example, some of the generation rules for f2(x) are as follows:

[0053] Table 1. Deviation Correction Relationship under Automatic Desuperheating Water Injection

[0054] Deviation (°C) -20 -10 0 10 50 Deviation correction (°C) -10 -5 0 10 50

[0055] When a deviation occurs between the setpoint and the actual outlet temperature of the high-temperature reheater on side B, the flue gas damper setpoint is adjusted in advance based on the deviation, i.e., the low-temperature reheater outlet temperature setpoint is adjusted in advance. After correction, this setpoint is superimposed on the guide temperature setpoint. Before superposition, the advanced corrected low-temperature reheater outlet temperature setpoint can be directly used for control via the second PID control logic; after superposition, the superimposed result is used as the latest low-temperature reheater outlet temperature setpoint for control via the second PID control logic. In other words, the flue gas damper setpoint is first coarsely adjusted based on the high-temperature reheater outlet temperature to further improve response speed, and then finely adjusted based on the guide temperature setpoint to improve control accuracy.

[0056] Further optimization can also include a setpoint bias function, which can compensate for external influences such as heat absorption and release in the pipeline. Users can manually design this bias value, and then superimpose this bias with the advanced adjustment of the low-temperature reheater outlet temperature setpoint and the lead-in temperature setpoint. The final superposition result is used as the latest low-temperature reheater outlet temperature setpoint, and then controlled by the second PID control logic.

[0057] Further, before step S2, it is first determined whether the reheater baffle on side A is in automatic control mode. If so, step S2 is executed to achieve joint temperature control of the baffle and the desuperheating water. Otherwise, the baffle does not participate in temperature control, meaning that the actual value and set value on the input side of the second PID control logic are the same, or in other words, the second PID control logic is not active. Correspondingly, as... Figure 4 As shown, when the adjustment command is finally issued to the reheat flue gas damper on side A, if the damper is in automatic control mode, the second PID control logic issues an adjustment command to the damper based on the comparison between the setpoint and the actual outlet temperature of the low-temperature reheater. This adjustment adjusts the opening of the damper to ensure that the actual outlet temperature of the low-temperature reheater equals the setpoint or its allowable deviation. If the damper is in manual control mode, an adjustment command is issued to the damper based on the manually adjusted damper control command. Since there are two dampers on one side, referred to as damper 1 and damper 2, adjustment commands are issued to both dampers respectively. By seamlessly embedding the reheater flue gas regulating damper control logic into the unit via a switching module, and using the dynamic optimization control mode for the reheater flue gas regulating damper to trigger the operation, the conventional reheater flue gas regulating damper control is not affected, ensuring seamless control of the unit. Figure 4The function f1(x) is the allocation function for the reheater flue gas damper and the superheater flue gas damper. The generation rules for the reheater flue gas damper are as follows:

[0058] Table 2 Relationships in the Formation Rules of Reheater Flue Gas Damperes

[0059] Reheater flue gas damper command (%) 0 55 110 Instruction correction (%) 0 55 110

[0060] More preferably, this scheme dynamically adjusts the upper and lower limit parameters of the adaptive PID controller based on the unit load range and the thermal efficiency under different loads. This ensures that the opening of the reheater flue gas regulating damper is matched to the high-temperature reheater outlet temperature within a reasonable range, preventing phenomena that could affect unit safety, such as tail flue vibration caused by excessively small reheater flue gas damper opening under high loads and excessive low-temperature reheater outlet pipe wall temperature under low loads. Figure 3 In the process, there is a corresponding PID for 900MW and above, and a corresponding PID for below 900MW. The PID control logic is selected adaptively according to the load, that is, the upper and lower limit parameters of the adaptive PID. Figure 2 Taking two intervals as an example, in actual use, there may be only one interval, or there may be three or more intervals.

[0061] Figure 5 Taking the actual operation of a 1050MW ultra-supercritical thermal power unit as an example, the application diagram of this scheme for optimized reheater damper control is shown. As can be seen from the diagram, the overall desuperheating water consumption is very low during the control process implemented by this scheme. This is because this scheme minimizes desuperheating water consumption by controlling the high reheat inlet temperature and the low reheat outlet temperature to be close, thus eliminating the deviation between the high reheat inlet temperature and the low reheat outlet temperature. Furthermore, it can be seen that the damper command has several distinct downward phases, and these phases occur when the load increases. This is because, in a dynamic process, when the load increases, the flue gas volume increases, and the reheater absorption temperature increases at the same damper opening. Therefore, the damper opening decreases significantly during these phases. Thus, it can be seen that the control method implemented by this scheme can achieve good control results even under load variations while significantly reducing the use of desuperheating water. It ensures both unit economy and effective control of the reheat steam outlet temperature, thereby maximizing the safety and economy of the power plant.

[0062] The actual temperature values ​​described herein are obtained using temperature sensors or other temperature-detecting devices installed at appropriate locations. The permissible deviation ranges described herein are determined by those skilled in the art based on specific circumstances; depending on the actual situation, the permissible deviation ranges may be the same or different. The specific embodiments described herein are merely illustrative examples of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization, characterized in that, include: S1. Obtain the actual value of the high-temperature reheater outlet temperature; S2. The first control logic generates a value based on the actual value of the high temperature reheater outlet temperature and the set value of the high temperature reheater outlet temperature, such that the actual value of the high temperature reheater outlet temperature is equal to the set value of the high temperature reheater outlet temperature or the set value of the desuperheating water inlet temperature within its allowable deviation range. S4. Determine the low-temperature reheater outlet temperature setting value based on the desuperheating water inlet temperature setting value; S5. Compare the actual value of the low temperature reheater outlet temperature with the set value of the low temperature reheater outlet temperature, and adjust the flue gas damper through the second control logic so that the actual value of the low temperature reheater outlet temperature continuously approaches the set value of the low temperature reheater outlet temperature. S6. The first control logic continuously adjusts the desuperheating water valve of the reheater based on the change in the actual value of the low temperature reheater outlet temperature and the set value of the desuperheating water inlet temperature, so that the actual value of the high temperature reheater outlet temperature is equal to the set value of the high temperature reheater outlet temperature or within its allowable deviation range. S7. Repeat steps S5-S6 until the desuperheating water valve is completely closed; When the actual value of the high-temperature reheater outlet temperature exceeds the allowable deviation range of the high-temperature reheater outlet temperature setpoint, repeat steps S1-S7.

2. The method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization according to claim 1, characterized in that, Between steps S2 and S4, there is also step S3: The actual value of the low temperature reheater outlet temperature is obtained at this time. The first control logic adjusts the reheater desuperheating water valve according to the actual value of the low temperature reheater outlet temperature and the set value of the desuperheating water inlet temperature, so that the actual value of the high temperature reheater outlet temperature is equal to the set value of the high temperature reheater outlet temperature or within its allowable deviation range. Step S6 is as follows: The first control logic continuously adjusts the desuperheating water valve of the reheater based on the change in the actual value of the low-temperature reheater outlet temperature and the newly generated desuperheating water inlet temperature setpoint, so that the actual value of the high-temperature reheater outlet temperature is equal to the high-temperature reheater outlet temperature setpoint or within its allowable deviation range; and Step S7 is as follows: Steps S4-S6 are repeated continuously until the desuperheating water valve is completely closed and the actual value of the high-temperature reheater outlet temperature is equal to the high-temperature reheater outlet temperature setpoint or within its allowable deviation range.

3. The method for controlling the reheat steam outlet temperature of thermal power units based on dynamic parameter optimization according to claim 2, characterized in that, In step S3, the setpoint of the desuperheating water inlet temperature is used as the setpoint of the low-temperature reheater outlet temperature.

4. The method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization according to claim 2, characterized in that, Step S3 is preceded by: The deviation correction function f2(x) is used to advance the setting value of the low temperature reheater outlet temperature based on the deviation between the actual value of the high temperature reheater outlet temperature and the set value of the high temperature reheater outlet temperature. In step S3, the advance correction result is superimposed with the desuperheating water inlet temperature setpoint as the low-temperature reheater outlet temperature setpoint.

5. The method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization according to claim 4, characterized in that, In step S3, the set value of the desuperheating water inlet temperature is superimposed with the bias value set by the user as the set value of the low temperature reheater outlet temperature. Alternatively, in step S3, the advanced correction result, the desuperheating water inlet temperature setpoint, and the user-set bias value are superimposed as the low-temperature reheater outlet temperature setpoint.

6. The method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization according to claim 1, characterized in that, Before step S2, first determine whether the desuperheating water control is in automatic mode. If so, directly take the high-temperature reheater outlet temperature setpoint itself; otherwise, determine the adaptive setpoint based on the load and use the adaptive setpoint as the high-temperature reheater outlet temperature setpoint.

7. The method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization according to claim 1, characterized in that, Before step S4, first determine whether the flue gas damper is in automatic mode. If so, execute the subsequent steps; otherwise, the second control logic does not work.

8. The method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization according to claim 1, characterized in that, The system has different second control logics pre-stored according to different load ranges. In step S5, the corresponding second control logic is adaptively selected according to the current load. Both the first and second control logics are PID control logics.

9. The method for controlling the reheat steam outlet temperature of a thermal power unit based on dynamic parameter optimization according to any one of claims 1-8, characterized in that, The outlet of the low-temperature reheater on side A is connected to the inlet of the high-temperature reheater on side B, and the outlet of the low-temperature reheater on side B is connected to the inlet of the high-temperature reheater on side A, so that water vapor can flow crosswise between side A and side B.

10. A reheat steam outlet temperature control system for thermal power units based on dynamic parameter optimization, characterized in that, Used to implement the reheat steam outlet temperature control method for thermal power units based on dynamic parameter optimization as described in any one of claims 1-9.

Images