A primary frequency modulation dead zone self-adaptive adjustment method for a thermal power unit

Abstract

This invention discloses an adaptive adjustment method for the primary frequency regulation dead zone of thermal power units, relating to the field of thermal power generation technology. The invention includes the following steps: collecting relevant data; first-order filtering of bed temperature to calculate the rate of change and limiting the speed; sliding filtering of bed pressure difference after deducting the pressure drop of the air distribution plate and taking the larger value with the minimum fluidization pressure difference to obtain the effective bed material pressure difference; setting a basic dead zone, with the initial dead zone in both load increase and decrease directions taking this basic value; when the frequency deviation is negative, multiplying and limiting the effective bed material pressure difference by the portion of bed temperature rate decrease exceeding the limit to obtain the load increase dead zone; when it is positive, multiplying and limiting the effective bed material pressure difference by the effective bed material pressure difference to obtain the load decrease dead zone; limiting the amplitude and restricting the incremental rate of the load increase and decrease dead zones and performing first-order smoothing to obtain the final dead zone; calculating the frequency deviation between the grid frequency and the rated frequency; when the frequency deviation is less than the negative final load increase dead zone, superimposing to obtain the effective deviation; when it is greater than the final load decrease dead zone, subtracting to obtain the effective deviation; generating load increments and limiting their amplitude and speed.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology, and in particular relates to an adaptive adjustment method for the primary frequency regulation dead zone of thermal power units. Background Technology

[0002] With the continuous increase in the proportion of new energy power generation, the requirements of the power grid on the primary frequency regulation capability of thermal power units are becoming increasingly stringent. Thermal power units need to quickly adjust their output according to the frequency deviation of the power grid to maintain the frequency stability of the power system. Circulating fluidized bed boilers, due to their advantages such as strong fuel adaptability and low pollutant emissions, occupy an important position in the fields of combined heat and power and low-quality coal utilization, and have become one of the main boiler types participating in the primary frequency regulation of the power grid. In the primary frequency regulation control of circulating fluidized bed boiler thermal power units, a fixed frequency dead zone limit is usually set. When the frequency deviation of the power grid exceeds the dead zone range, the primary frequency regulation action is triggered, and a corresponding load increment command is generated according to the speed regulation inequality curve, which changes the unit output through the opening of the turbine high-pressure regulating valve.

[0003] However, the aforementioned fixed dead zone setting method faces safety operation risks due to the boiler's combustion characteristics when applied to circulating fluidized bed boilers. This risk stems from the limited heat storage in the dense phase zone of the circulating fluidized bed boiler and the directional sensitivity of the bed temperature dynamics. Combustion in a circulating fluidized bed boiler primarily occurs in the dense phase zone composed of a large amount of high-temperature bed material, and the bed material quantity directly determines the boiler's heat storage capacity. Primary frequency regulation achieves power response by changing the opening of the high-pressure regulating valve; this process is essentially a rapid extraction or accumulation of heat stored in the boiler. In the load-increasing direction, the high-pressure regulating valve opens wider, the steam flow increases sharply, heat stored in the dense phase zone is rapidly extracted, and the bed temperature tends to decrease. In the load-reducing direction, the high-pressure regulating valve closes less, the steam flow decreases sharply, heat accumulates in the dense phase zone, and the bed temperature tends to increase. Excessively low bed temperatures may lead to fluidization deterioration or even coking, while excessively high bed temperatures threaten the safety of the heating surfaces and desulfurization efficiency.

[0004] The safety risks caused by fixed dead zones are fundamentally different from the over-adjustment problem of heat storage in conventional pulverized coal boilers. First, the main heat storage component of circulating fluidized bed boilers is the incandescent bed material particles in the dense phase zone. The heat storage capacity is closely related to the bed material inventory, which changes dynamically with operating conditions, fuel ash content, and ash discharge rate, and is not a constant value. Second, the safety boundaries of bed temperature are not equal in the directions of load increase and decrease. The risk of low temperature when the bed temperature drops too quickly needs to be suppressed more promptly than when the bed temperature rises, because once low-temperature coking occurs, it is irreversible. Third, the rate of change of bed temperature in the dense phase zone is constrained by the bed material inventory. The smaller the bed material inventory, the greater the range of bed temperature changes caused by the same amount of steam disturbance, that is, the weaker the heat storage buffer capacity.

[0005] Under these conditions, if the dead zone of primary frequency regulation remains fixed, when the bed material inventory is low and the bed temperature is rapidly changing in a dangerous direction, the frequency regulation action will further exacerbate the deterioration of the bed temperature, causing fluidization instability or coking accidents. The coking mentioned above specifically refers to the phenomenon in the dense phase zone of a circulating fluidized bed boiler where molten ash clumps together on the air distribution plate due to excessively low local temperatures. Once formed, it destroys the fluidization uniformity and, in severe cases, forces the unit to shut down unplanned. If the dead zone is artificially set to be large to avoid coking, it will cause the unit to respond slowly to the grid frequency deviation and fail to meet the requirements of the primary frequency regulation technical standard. Therefore, the following solutions are proposed to address the above problems. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0007] This invention relates to an adaptive adjustment method for the primary frequency regulation dead zone of thermal power units, comprising the following steps:

[0008] Step S1: The distributed control system synchronously collects the grid frequency, original bed temperature, original bed pressure difference signal, actual power generation of the unit, main steam pressure, and comprehensive valve position command of the high-pressure regulating valve with a control cycle of no more than 1 second, and retrieves the set speed regulation inequality and rated power of the unit.

[0009] Step S2: Perform first-order inertial filtering on the original bed temperature to obtain the filtered bed temperature; calculate the bed temperature change rate using the filtered bed temperatures of adjacent periods and limit the rate of bed temperature change; perform moving average filtering on the original bed pressure difference signal to obtain the average bed pressure difference; determine the air distribution plate pressure drop corresponding to the average bed pressure difference using the cold-calibrated air distribution plate resistance curve; compare the average bed pressure difference after deducting the air distribution plate pressure drop with the preset minimum fluidization pressure difference lower limit and take the larger value to obtain the effective bed material pressure difference that characterizes the bed material inventory online;

[0010] Step S3: Set the basic symmetric dead zone limit value, decouple the dead zones in the load increase direction and the load decrease direction, and take the initial load increase dead zone and the initial load decrease dead zone as the basic symmetric dead zone limit value.

[0011] Step S4: Under the condition that the frequency deviation is negative, the adaptive dead zone correction term in the load increase direction is obtained by multiplying the excess portion of the bed temperature drop rate and the reciprocal of the effective bed material pressure difference and using a limiting operation; the load increase dead zone is obtained by adding the basic dead zone to the adaptive dead zone correction term in the load increase direction.

[0012] Step S5: Under the condition that the frequency deviation is positive and exceeds the dead zone, the adaptive dead zone correction term in the load reduction direction is obtained by multiplying the excess portion of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference and using a limiting operation; the load reduction dead zone is obtained by subtracting the adaptive dead zone correction term in the load reduction direction from the basic dead zone and comparing it with the preset minimum dead zone limit and taking the larger value.

[0013] Step S6: Perform amplitude limiting and incremental rate limiting on the load increase dead zone and the load decrease dead zone, and then perform first-order inertial smoothing on the two dead zones after speed limiting to obtain the final load increase dead zone and the final load decrease dead zone for logical judgment.

[0014] Step S7: Obtain the frequency deviation by subtracting the collected grid frequency from the rated frequency; when the frequency deviation is less than the negative final load increase dead zone, determine that the primary frequency regulation in the load increase direction is triggered, and obtain the effective deviation by adding the frequency deviation to the final load increase dead zone; when the frequency deviation is greater than the final load decrease dead zone, determine that the primary frequency regulation in the load decrease direction is triggered, and obtain the effective deviation by subtracting the frequency deviation from the final load decrease dead zone; obtain the primary frequency regulation load increment by proportional calculation using the effective deviation, speed regulation inequality rate, and rated power, and limit the amplitude and load change rate of the primary frequency regulation load increment;

[0015] Step S8: The primary frequency regulation load increment processed by amplitude and speed limiting is algebraically superimposed with the current unit load command to form a total load command, which is then sent to the turbine digital electro-hydraulic control system to adjust the opening of the high-pressure regulating valve and achieve power response. While the action is being executed, operating parameters are continuously collected, filtered, and returned to step S2, so that the load increase dead zone and load decrease dead zone are adaptively adjusted in a closed loop according to the real-time status of the unit.

[0016] Further, step S1 includes the following steps:

[0017] Step S11: Obtain the power grid frequency using a turbine speed probe or synchronous phasor measurement device. The rated frequency is denoted as [missing information]. ;

[0018] Step S12: The original bed temperature is obtained by measuring the initial bed temperature using at least three thermocouples in the lower part of the dense phase zone of the circulating fluidized bed boiler, and by taking the arithmetic mean after removing outliers. ;

[0019] Step S13: Obtain the original bed differential pressure signal using the differential pressure transmitters at the upper and lower parts of the dense phase region. ;

[0020] Step S14: Collect the actual power output of the generating unit Main steam pressure High-pressure regulating valve integrated valve position command And retrieve the speed unequalization rate that has been set in the distributed control system. and the rated power of the unit .

[0021] Furthermore, step S2 includes the following steps:

[0022] Step S21: Suppress high-frequency noise introduced by fuel fluctuations and fluidization disturbances through first-order inertial filtering, using the current original bed temperature. Compared with the previous cycle filter value Weighted values ​​are applied to obtain the filtered bed temperature. The calculation formula is:

[0023] ;

[0024] In the formula, The filter bed temperature for the current control cycle. The filter bed temperature from the previous control cycle. The original bed temperature collected during the current control cycle. These are the filter coefficients; filter coefficients By filtering time constant and control cycle Determined, using relational expressions Perform calculations. Hold for 3 to 5 seconds;

[0025] Step S22: Calculate the bed temperature change rate using the filtered bed temperature of adjacent periods, and obtain the dynamic trend of bed temperature change using a differential formula with amplitude limiting. The calculation formula is:

[0026] ;

[0027] In the formula, The rate of change of bed temperature during the current control cycle. The filter bed temperature for the current control cycle. The filter bed temperature from the previous control cycle. To control the cycle, the calculated bed temperature change rate is rate-limited, and abrupt changes exceeding 10 K / min are eliminated.

[0028] Step S23: Process the raw bed pressure difference signal using a moving average filter. The average bed pressure difference was obtained using a window duration of 10 seconds. ;

[0029] Step S24: Determine the pressure drop of the air distribution plate corresponding to the average bed pressure difference using the cold-calibrated air distribution plate resistance curve. ;

[0030] Step S25: Compare the average bed pressure difference after deducting the pressure drop from the air distribution plate with the preset minimum fluidization pressure difference lower limit. By comparing and selecting the larger value, the effective bed material pressure difference, which represents the bed material inventory online, is obtained. The calculation formula is:

[0031] ;

[0032] In the formula, For effective bed material pressure differential, The average bed pressure difference is the result of moving average filtering. The pressure drop of the air distributor is determined from the average bed pressure difference using the cold-calibrated air distributor resistance curve. The lower limit constant of the pressure differential required to maintain minimum fluidization; effective bed pressure differential. The system reflects the bed material inventory level online; the lower the pressure differential, the less bed material is in stock.

[0033] Furthermore, step S3 includes the following steps:

[0034] Step S31: Based on the primary frequency regulation technical standards of the power grid and considering the combustion characteristics of the circulating fluidized bed boiler, set the basic symmetrical dead zone limit value. ;

[0035] Step S32: Decouple the dead zones in the load increase direction and the load decrease direction, and set the initial load increase dead zone. With initial load reduction dead zone All are taken as the basic symmetric dead zone limit value. .

[0036] Furthermore, step S4 includes the following steps:

[0037] Step S41: In frequency deviation Under certain operating conditions, the power grid requires the unit to increase its output, causing the high-pressure regulating valve to open wider, resulting in a decrease in the bed temperature in the dense phase zone of the boiler. When the bed temperature decrease rate is too high and the bed material inventory is low, an adaptive dead zone correction term for the load increase direction is obtained by multiplying the excess portion of the bed temperature decrease rate with the reciprocal of the effective bed material pressure difference and performing a limiting operation. The calculation formula is:

[0038] ;

[0039] In the formula, For the adaptive dead zone correction term in the direction of load increase, To correct the gain in the direction of load increase, The effect of a single frequency modulation action on the bed temperature drop is preset. The bed temperature change rate obtained in step S22; This represents the tolerance threshold for the rate of bed temperature decrease. ; This represents the absolute value of the rate of decrease in bed temperature only. Exceeding the tolerance threshold The value is positive if it is positive, otherwise it is zero. The effective bed material pressure difference obtained in step S25; It is a very small positive number, used to prevent division from being meaningless when the effective bed material pressure difference is zero;

[0040] Step S42: Obtain the load increase dead zone for the current control cycle by adding the base dead zone to the correction term using an addition operation. The calculation formula is:

[0041] ;

[0042] In the formula, This is the load increase dead zone for the current control cycle. This is the initial load increase dead zone. The adaptive dead zone correction term for the load increase direction obtained in step S41; when the effective bed material pressure difference... Smaller and the rate of bed temperature drop exceeds the tolerance threshold At that time, the correction item As the value increases, the load dead zone increases. Accordingly, the amplitude and frequency of frequency regulation in the direction of load increase should be appropriately reduced to provide time margin for bed temperature recovery.

[0043] Furthermore, step S5 includes the following steps:

[0044] Step S51: In frequency deviation Furthermore, when operating outside the dead zone, the unit needs to reduce output, the high-pressure regulating valve closes slightly, and the bed temperature rises. When the bed temperature rises rapidly and the bed material inventory is low, the adaptive dead zone correction term for the load reduction direction is obtained by multiplying the excess portion of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference with a limiting operation. The calculation formula is:

[0045] ;

[0046] In the formula, For the adaptive dead zone correction term in the load reduction direction, To correct the gain in the direction of load reduction, ; This represents the tolerance threshold for the rate of bed temperature rise. ; This indicates that only when the bed temperature rises at a certain rate Exceeding the tolerance threshold The value is positive if it is positive, otherwise it is zero.

[0047] Step S52: Subtract the correction term from the base dead zone and perform maximum limit calculation with the preset minimum dead zone. By comparison, the dead zone in the load reduction direction can be obtained. The calculation formula is:

[0048] ;

[0049] In the formula, This is the load reduction dead zone for the current control cycle. The minimum allowable dead zone limit, This is the initial deload dead zone; when the bed temperature rise rate exceeds the tolerance threshold. And effective bed material pressure difference When smaller, the correction term Increase, reduce load dead zone The corresponding reduction makes it easier to trigger the primary frequency regulation in the direction of load reduction, and assists the bed temperature to drop by prioritizing the reduction of unit output.

[0050] Furthermore, step S6 includes the following steps:

[0051] Step S61: Apply the load increase dead zone obtained in step S42 and the load reduction dead zone obtained in step S52 Limit at Within the interval, in the formula, The minimum allowable dead zone limit, The maximum allowable dead zone limit, Set the frequency to 0.1Hz or according to the unit's safety documentation;

[0052] Step S62: Limit the rate of dead zone increment between adjacent control cycles, and set the maximum allowable change per second to 0.005 Hz / s;

[0053] Step S63: Based on the amplitude and speed limits, a first-order inertial smoothing process is applied, and the smoothing dead zone of the previous cycle and the dead zone after the speed limit in this cycle are weighted to obtain the final load increase dead zone used for logical judgment. and load reduction dead zone The smoothing formula is as follows:

[0054] ;

[0055] ;

[0056] In the formula, , These are the final load increase dead zone and the final load decrease dead zone after smoothing the current control cycle; , These are the final load increase dead zone and the final load decrease dead zone of the previous control cycle, respectively. , These are the load increase dead zone and load decrease dead zone after amplitude and rate limits are applied during the current control cycle; The smoothing coefficient is determined by the smoothing time constant. and control cycle Determined, using relational expressions Perform calculations. Take approximately 2 seconds.

[0057] Furthermore, step S7 includes the following steps:

[0058] Step S71: By collecting the power grid frequency With rated frequency The frequency deviation is obtained by using interpolation calculation. The formula is as follows:

[0059] ;

[0060] In the formula, For frequency deviation, For the rated frequency, The power grid frequency collected in step S1;

[0061] Step S72: When the frequency deviation Less than the negative final load dead zone At that time, the direction of load increase is determined by primary frequency regulation triggering. By using directional addition to calculate the frequency deviation and the final load increase dead zone, the effective deviation amount for crossing the dead zone is obtained. The formula is as follows:

[0062] ;

[0063] In the formula, This is the effective deviation used to calculate the load increment. For frequency deviation, This is the final load increase dead zone obtained in step S63;

[0064] When frequency deviation Greater than the final load reduction dead zone At that time, the direction of load reduction is determined by primary frequency regulation triggering. The effective deviation is obtained by subtraction between the frequency deviation and the final load reduction dead zone. The formula is as follows:

[0065] ;

[0066] If frequency deviation In Within the range, if the frequency modulation does not operate, the effective deviation is... Set to zero;

[0067] Step S73: Using the effective deviation amount Speed ​​unequalization and rated power The primary frequency regulation load increment is obtained by using proportional calculation. The formula is as follows:

[0068] ;

[0069] In the formula, For primary frequency regulation load increment, For the rated frequency, For speed unequal distribution, The rated power of the unit; frequency deviation when triggered by load increase. Negative, effective deviation Negative, primary frequency regulation load increment A positive value corresponds to an increase in unit load; when a load reduction is triggered, the frequency deviation... If positive, the effective deviation is... Positive, primary frequency regulation load increment A negative value corresponds to a reduction in the unit load;

[0070] Step S74: Calculate the generated primary frequency regulation load increment. Implement amplitude limits and load change rate limits.

[0071] Furthermore, step S8 includes the following steps:

[0072] Step S81: The primary frequency regulation load increment processed by step S7 (amplitude and speed limiting) is... The current unit load command is algebraically superimposed to form a total load command, which is then transmitted to the turbine digital electro-hydraulic control system.

[0073] Step S82: The turbine digital electro-hydraulic control system adjusts the opening of the high-pressure regulating valve according to the total load command to achieve primary frequency regulation response of the power;

[0074] Step S83: While the action is being executed, continuously collect and filter the bed temperature and bed pressure operating parameters, and return to step S2.

[0075] Furthermore, in step S8, when the bed temperature change rate recovers to within the tolerance threshold or the effective bed material pressure difference rebounds, the adaptive dead zone correction term in the load increase direction... Gradually decrease, load increase dead zone Gradually revert to the base dead zone value Nearby; Adaptive dead zone correction term in the direction of load reduction Consequently, the load reduction dead zone decreases. Restore to base dead zone value A dynamic balance is achieved between primary frequency regulation response capability and combustion safety of circulating fluidized bed boilers.

[0076] The present invention has the following beneficial effects:

[0077] 1. In the load increase direction, this invention utilizes the bed temperature drop rate and bed material inventory to construct an adaptive dead zone correction term. When the bed temperature drops rapidly and the bed material is small, the load increase dead zone automatically expands, appropriately suppressing the frequency and amplitude of frequency regulation actions and preventing the bed temperature from being further lowered. This reduces the probability of fluidization deterioration and coking tendency caused by a sudden drop in bed temperature, ensuring the combustion safety and stable operation of the dense phase zone of the circulating fluidized bed boiler.

[0078] 2. In terms of load reduction, this invention utilizes the bed temperature rise rate and bed material inventory to construct an adaptive dead zone correction term. When the bed temperature rises rapidly, the load reduction dead zone automatically shrinks, making it easier for the unit to respond to power reduction frequency regulation commands and assisting the bed temperature to fall back during the load reduction process. In this way, the continuous accumulation of high-temperature conditions is avoided, the negative impact on the lifespan of the furnace heating surfaces and the desulfurization reaction efficiency is reduced, and the coordination between frequency regulation and bed temperature control is achieved.

[0079] 3. This invention decouples and independently and adaptively adjusts the dead zones in both the rising and falling directions, matching the level of primary frequency regulation participation with the real-time heat storage status of the boiler. When the bed material inventory is sufficient and the bed temperature changes steadily, a high frequency regulation sensitivity can be maintained; when the bed material inventory is low and the bed temperature changes drastically, the dead zones in each direction are adjusted accordingly to protect the boiler. This bidirectional differentiated regulation, in principle, balances the frequency regulation requirements of the power grid and the operational boundary constraints of the circulating fluidized bed boiler.

[0080] 4. This invention implements incremental rate limiting and inertial smoothing processing on the adaptive dead zone to ensure that the dead zone value changes smoothly without abrupt changes, avoiding sudden changes in the primary frequency regulation power command caused by sudden changes in the dead zone; in conjunction with limiting the amplitude and speed of the final load increment, it reduces the ineffective fluctuations of the high-pressure regulating valve and the turbine regulating system, which helps to reduce the operating frequency of mechanical components and slow down system wear and thermal shock accumulation.

[0081] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0082] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0083] Figure 1 This is a flowchart illustrating an adaptive adjustment method for the primary frequency regulation dead zone of a thermal power unit according to the present invention. Detailed Implementation

[0084] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0085] Please see Figure 1 As shown, this invention is an adaptive adjustment method for the primary frequency regulation dead zone of a thermal power unit, comprising the following steps:

[0086] Step S1: The distributed control system synchronously collects the grid frequency, original bed temperature, original bed pressure difference signal, actual power generation of the unit, main steam pressure, and comprehensive valve position command of the high-pressure regulating valve with a control cycle of no more than 1 second, and retrieves the set speed regulation inequality and rated power of the unit.

[0087] Step S2: Perform first-order inertial filtering on the original bed temperature to obtain the filtered bed temperature; calculate the bed temperature change rate using the filtered bed temperatures of adjacent periods and limit the rate of bed temperature change; perform moving average filtering on the original bed pressure difference signal to obtain the average bed pressure difference; determine the air distribution plate pressure drop corresponding to the average bed pressure difference using the cold-calibrated air distribution plate resistance curve; compare the average bed pressure difference after deducting the air distribution plate pressure drop with the preset minimum fluidization pressure difference lower limit and take the larger value to obtain the effective bed material pressure difference that characterizes the bed material inventory online;

[0088] Step S3: Set the basic symmetrical dead zone limit value, decouple the dead zones in the load increase direction and the load decrease direction, and take the basic symmetrical dead zone limit value for both the initial load increase dead zone and the initial load decrease dead zone.

[0089] Step S4: Under the condition that the frequency deviation is negative, the adaptive dead zone correction term in the load increase direction is obtained by multiplying the over-limit portion of the bed temperature drop rate and the reciprocal of the effective bed material pressure difference and using a limiting operation; the load increase dead zone is obtained by adding the basic dead zone and the adaptive dead zone correction term in the load increase direction.

[0090] Step S5: Under the condition that the frequency deviation is positive and exceeds the dead zone, the adaptive dead zone correction term in the load reduction direction is obtained by multiplying the over-limit portion of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference and using amplitude limiting calculation; by subtracting the adaptive dead zone correction term in the load reduction direction from the basic dead zone and comparing it with the preset minimum dead zone limit and taking the larger value, the load reduction dead zone is obtained.

[0091] Step S6: Perform amplitude limiting and incremental rate limiting on the load increase dead zone and load decrease dead zone, and then perform first-order inertial smoothing on the two dead zones after speed limiting to obtain the final load increase dead zone and final load decrease dead zone for logical judgment.

[0092] Step S7: Obtain the frequency deviation by subtracting the collected grid frequency from the rated frequency; when the frequency deviation is less than the negative final load increase dead zone, determine that the primary frequency regulation in the load increase direction is triggered, and obtain the effective deviation by adding the frequency deviation to the final load increase dead zone; when the frequency deviation is greater than the final load decrease dead zone, determine that the primary frequency regulation in the load decrease direction is triggered, and obtain the effective deviation by subtracting the frequency deviation from the final load decrease dead zone; obtain the primary frequency regulation load increment by proportional calculation using the effective deviation, speed regulation inequality rate, and rated power, and limit the amplitude and load change rate of the primary frequency regulation load increment;

[0093] Step S8: The primary frequency regulation load increment processed by amplitude and speed limiting is algebraically superimposed with the current unit load command to form a total load command, which is then sent to the turbine digital electro-hydraulic control system to adjust the opening of the high-pressure regulating valve and achieve power response. While the action is being executed, operating parameters are continuously collected, filtered, and returned to step S2, so that the load increase dead zone and load decrease dead zone are adaptively adjusted in a closed loop according to the real-time status of the unit.

[0094] Step S1 includes the following steps:

[0095] Step S11: Obtain the power grid frequency using a turbine speed probe or synchronous phasor measurement device. The rated frequency is denoted as [missing information]. ;

[0096] Step S12: The original bed temperature is obtained by measuring the initial bed temperature using at least three thermocouples in the lower part of the dense phase zone of the circulating fluidized bed boiler, and by taking the arithmetic mean after removing outliers. ;

[0097] Step S13: Obtain the original bed differential pressure signal using the differential pressure transmitters at the upper and lower parts of the dense phase region. ;

[0098] Step S14: Collect the actual power output of the generating unit Main steam pressure High-pressure regulating valve integrated valve position command And retrieve the speed unequalization rate that has been set in the distributed control system. and the rated power of the unit .

[0099] Step S2 includes the following steps:

[0100] Step S21: Suppress high-frequency noise introduced by fuel fluctuations and fluidization disturbances through first-order inertial filtering, using the current original bed temperature. Compared with the previous cycle filter value Weighted values ​​are applied to obtain the filtered bed temperature. The calculation formula is:

[0101] ;

[0102] In the formula, The filter bed temperature for the current control cycle. The filter bed temperature from the previous control cycle. The original bed temperature collected during the current control cycle. These are the filter coefficients; filter coefficients By filtering time constant and control cycle Determined, using relational expressions Perform calculations. Hold for 3 to 5 seconds;

[0103] Step S22: Calculate the bed temperature change rate using the filtered bed temperature of adjacent periods, and obtain the dynamic trend of bed temperature change using a differential formula with amplitude limiting. The calculation formula is:

[0104] ;

[0105] In the formula, The rate of change of bed temperature during the current control cycle. The filter bed temperature for the current control cycle. The filter bed temperature from the previous control cycle. To control the cycle, the calculated bed temperature change rate is rate-limited, and abrupt changes exceeding 10 K / min are eliminated.

[0106] Step S23: Process the raw bed pressure difference signal using a moving average filter. The average bed pressure difference was obtained using a window duration of 10 seconds. ;

[0107] Step S24: Determine the pressure drop of the air distribution plate corresponding to the average bed pressure difference using the cold-calibrated air distribution plate resistance curve. ;

[0108] Step S25: Compare the average bed pressure difference after deducting the pressure drop from the air distribution plate with the preset minimum fluidization pressure difference lower limit. By comparing and selecting the larger value, the effective bed material pressure difference, which represents the bed material inventory online, is obtained. The calculation formula is:

[0109] ;

[0110] In the formula, For effective bed material pressure differential, The average bed pressure difference is the result of moving average filtering. The pressure drop of the air distributor is determined from the average bed pressure difference using the cold-calibrated air distributor resistance curve. The lower limit constant of the pressure differential required to maintain minimum fluidization; effective bed pressure differential. The system reflects the bed material inventory level online; the lower the pressure differential, the less bed material is in stock.

[0111] Step S3 includes the following steps:

[0112] Step S31: Based on the primary frequency regulation technical standards of the power grid and considering the combustion characteristics of the circulating fluidized bed boiler, set the basic symmetrical dead zone limit value. ;

[0113] Step S32: Decouple the dead zones in the load increase direction and the load decrease direction, and set the initial load increase dead zone. With initial load reduction dead zone All are taken as the basic symmetric dead zone limit values .

[0114] Step S4 includes the following steps:

[0115] Step S41: In frequency deviation Under certain operating conditions, the power grid requires the unit to increase its output, causing the high-pressure regulating valve to open wider, resulting in a decrease in the bed temperature in the dense phase zone of the boiler. When the bed temperature decrease rate is too high and the bed material inventory is low, an adaptive dead zone correction term for the load increase direction is obtained by multiplying the excess portion of the bed temperature decrease rate with the reciprocal of the effective bed material pressure difference and performing a limiting operation. The calculation formula is:

[0116] ;

[0117] In the formula, For the adaptive dead zone correction term in the direction of load increase, To correct the gain in the direction of load increase, The effect of a single frequency modulation action on the bed temperature drop is preset. The bed temperature change rate obtained in step S22; This represents the tolerance threshold for the rate of bed temperature decrease. ; This represents the absolute value of the rate of decrease in bed temperature only. Exceeding the tolerance threshold The value is positive if it is positive, otherwise it is zero. The effective bed material pressure difference obtained in step S25; It is a very small positive number, used to prevent division from being meaningless when the effective bed material pressure difference is zero;

[0118] Step S42: Obtain the load increase dead zone for the current control cycle by adding the base dead zone to the correction term using an addition operation. The calculation formula is:

[0119] ;

[0120] In the formula, This is the load increase dead zone for the current control cycle. This is the initial load increase dead zone. The adaptive dead zone correction term for the load increase direction obtained in step S41; when the effective bed material pressure difference... Smaller and the rate of bed temperature drop exceeds the tolerance threshold At that time, the correction item As the value increases, the load dead zone increases. Accordingly, the amplitude and frequency of frequency regulation in the direction of load increase should be appropriately reduced to provide time margin for bed temperature recovery.

[0121] Step S5 includes the following steps:

[0122] Step S51: In frequency deviation Furthermore, when operating outside the dead zone, the unit needs to reduce output, the high-pressure regulating valve closes slightly, and the bed temperature rises. When the bed temperature rises rapidly and the bed material inventory is low, the adaptive dead zone correction term for the load reduction direction is obtained by multiplying the excess portion of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference with a limiting operation. The calculation formula is:

[0123] ;

[0124] In the formula, For the adaptive dead zone correction term in the load reduction direction, To correct the gain in the direction of load reduction, ; This represents the tolerance threshold for the rate of bed temperature rise. ; This indicates that only when the bed temperature rises at a certain rate Exceeding the tolerance threshold The value is positive if it is positive, otherwise it is zero.

[0125] Step S52: Subtract the correction term from the base dead zone and perform maximum limit calculation with the preset minimum dead zone. By comparison, the dead zone in the load reduction direction can be obtained. The calculation formula is:

[0126] ;

[0127] In the formula, This is the load reduction dead zone for the current control cycle. The minimum allowable dead zone limit, This is the initial deload dead zone; when the bed temperature rise rate exceeds the tolerance threshold. And effective bed material pressure difference When smaller, the correction term Increase, reduce load dead zone The corresponding reduction makes it easier to trigger the primary frequency regulation in the direction of load reduction, and assists the bed temperature to drop by prioritizing the reduction of unit output.

[0128] Step S6 includes the following steps:

[0129] Step S61: Apply the load increase dead zone obtained in step S42 and the load reduction dead zone obtained in step S52 Limit at Within the interval, in the formula, The minimum allowable dead zone limit, The maximum allowable dead zone limit, Set the frequency to 0.1Hz or according to the unit's safety documentation;

[0130] Step S62: Limit the rate of dead zone increment between adjacent control cycles, and set the maximum allowable change per second to 0.005 Hz / s;

[0131] Step S63: Based on the amplitude and speed limits, a first-order inertial smoothing process is applied, and the smoothing dead zone of the previous cycle and the dead zone after the speed limit in this cycle are weighted to obtain the final load increase dead zone used for logical judgment. and load reduction dead zone The smoothing formula is as follows:

[0132] ;

[0133] ;

[0134] In the formula, , These are the final load increase dead zone and the final load decrease dead zone after smoothing the current control cycle; , These are the final load increase dead zone and the final load decrease dead zone of the previous control cycle, respectively. , These are the load increase dead zone and load decrease dead zone after amplitude and rate limits are applied during the current control cycle; The smoothing coefficient is determined by the smoothing time constant. and control cycle Determined, using relational expressions Perform calculations. Take approximately 2 seconds.

[0135] Step S7 includes the following steps:

[0136] Step S71: By collecting the power grid frequency With rated frequency The frequency deviation is obtained by using interpolation calculation. The formula is as follows:

[0137] ;

[0138] In the formula, For frequency deviation, For the rated frequency, The power grid frequency collected in step S1;

[0139] Step S72: When the frequency deviation Less than the negative final load dead zone At that time, the direction of load increase is determined by primary frequency regulation triggering. By using directional addition to calculate the frequency deviation and the final load increase dead zone, the effective deviation amount for crossing the dead zone is obtained. The formula is as follows:

[0140] ;

[0141] In the formula, This is the effective deviation used to calculate the load increment. For frequency deviation, This is the final load increase dead zone obtained in step S63;

[0142] When frequency deviation Greater than the final load reduction dead zone At that time, the direction of load reduction is determined by primary frequency regulation triggering. The effective deviation is obtained by subtraction between the frequency deviation and the final load reduction dead zone. The formula is as follows:

[0143] ;

[0144] If frequency deviation In Within the range, if the frequency modulation does not operate, the effective deviation is... Set to zero;

[0145] Step S73: Using the effective deviation amount Speed ​​unequalization and rated power The primary frequency regulation load increment is obtained by using proportional calculation. The formula is as follows:

[0146] ;

[0147] In the formula, For primary frequency regulation load increment, For the rated frequency, For speed unequal distribution, The rated power of the unit; frequency deviation when triggered by load increase. Negative, effective deviation Negative, primary frequency regulation load increment A positive value corresponds to an increase in unit load; when a load reduction is triggered, the frequency deviation... If positive, the effective deviation is... Positive, primary frequency regulation load increment A negative value corresponds to a reduction in the unit load;

[0148] Step S74: Calculate the generated primary frequency regulation load increment. Implement amplitude limits and load change rate limits.

[0149] Step S8 includes the following steps:

[0150] Step S81: The primary frequency regulation load increment processed by step S7 (amplitude and speed limiting) is... The current unit load command is algebraically superimposed to form a total load command, which is then transmitted to the turbine digital electro-hydraulic control system.

[0151] Step S82: The turbine digital electro-hydraulic control system adjusts the opening of the high-pressure regulating valve according to the total load command to achieve primary frequency regulation response of the power;

[0152] Step S83: While the action is being executed, continuously collect and filter the bed temperature and bed pressure operating parameters, and return to step S2.

[0153] In step S8, when the bed temperature change rate recovers to within the tolerance threshold or the effective bed material pressure difference rebounds, the adaptive dead zone correction term in the load increase direction is applied. Gradually decrease, load increase dead zone Gradually revert to the base dead zone value Nearby; Adaptive dead zone correction term in the direction of load reduction Consequently, the load reduction dead zone decreases. Restore to base dead zone value , a dynamic balance is achieved between the primary frequency regulation response ability and the combustion safety of the circulating fluidized bed boiler.

[0154] A specific application of this embodiment is as follows:

[0155] This embodiment takes the domestic power grid's 300MW-class circulating fluidized bed (CFB) thermal power unit as the application object, and fully implements the primary frequency regulation dead zone adaptive adjustment method described in this invention. The core basic parameters of the unit are as follows:

[0156] Unit rated power , grid rated frequency , distributed control system (DCS) control cycle , the already tuned turbine speed regulation inequality rate in DCS (that is ), the designed bed temperature range in the dense phase zone of the CFB boiler supporting the unit , the lower limit of the differential pressure corresponding to the minimum fluidization state .

[0157] Step S1: Synchronous acquisition of operating parameters

[0158] Through the DCS with control cycle, synchronously acquire the following unit and grid operating parameters, and retrieve the preset tuning parameters:

[0159] Use a turbine speed probe to collect the real-time grid frequency , the rated frequency in this embodiment ;

[0160] Use 4 K-type thermocouples at the lower part of the dense phase zone of the CFB boiler to collect the original bed temperature, and take the arithmetic mean after removing outliers to obtain the original bed temperature ;

[0161] Use high-precision differential pressure transmitters at the upper and lower parts of the dense phase zone to collect the original bed differential pressure signal ;

[0162] Synchronously collect the actual power output of the unit , main steam pressure , high-pressure regulating valve comprehensive valve position command , retrieve the already tuned speed regulation inequality rate in DCS , unit rated power .

[0163] Step S2: Filtering processing of bed temperature and bed pressure signals, and calculating the effective bed material differential pressure

[0164] Step S21: First-order inertial filtering of bed temperature

[0165] Set the filtering time constant Combined with control cycle First calculate the filter coefficients. The calculation formula is:

[0166] ;

[0167] Substituting the values, we get:

[0168] ;

[0169] The current cycle filtered bed temperature is obtained by weighting the current original bed temperature with the filtered value from the previous cycle. The calculation formula is:

[0170] ;

[0171] In this embodiment, the initial bed temperature during a certain control cycle The temperature of the filter bed in the previous cycle Substituting, we get:

[0172] ;

[0173] Step S22: Calculation and Limitation of Bed Temperature Change Rate

[0174] Calculate the bed temperature change rate in the current control cycle based on the filtered bed temperatures of adjacent cycles. The calculation formula is:

[0175] ;

[0176] Substituting the above values, , , The calculation yields:

[0177] ;

[0178] Rate limits were imposed on the bed temperature change rate, and samples exceeding the limit were discarded. The mutation value, in this embodiment, exceeds the limit, and is therefore... Amplitude limiting is applied.

[0179] Step S23: Bed pressure differential moving average filtering

[0180] For the original bed differential pressure signal Use window duration The moving average filter, because the control period is The sliding window contains 50 consecutive sampling points, ultimately obtaining the average bed pressure difference. In this embodiment, under a certain working condition .

[0181] Step S24: Determine the pressure drop of the air distribution plate

[0182] Based on the cold-state calibration of the air distributor resistance curve of the boiler, the air distributor pressure drop corresponding to the current average bed pressure difference is matched. In this embodiment, under this working condition .

[0183] Step S25: Calculation of effective bed material pressure difference

[0184] Preset the lower limit of the pressure differential required to maintain minimum fluidization The effective bed material pressure difference, which represents the bed material inventory online, is obtained through a maximum value operation. The calculation formula is:

[0185] ;

[0186] Substituting the values, we get:

[0187] ;

[0188] This value reflects the bed material inventory level online; the lower the pressure differential, the less bed material is in stock.

[0189] Step S3: Setting the basic dead zone limit

[0190] Step S31: Setting the basic symmetric dead zone

[0191] Based on the combustion characteristics of CFB boilers, basic symmetrical dead zone limits are set. .

[0192] Step S32: Initialization of bidirectional dead-time decoupling

[0193] Decouple the dead zones in the load increase and load decrease directions, and set the initial load increase dead zone. With initial load reduction dead zone All are taken as the basic symmetric dead zone limit, that is:

[0194] ;

[0195] Synchronous preset dead zone boundary parameters: minimum allowable dead zone limit Maximum allowable dead zone limit .

[0196] Step S4: Adaptive adjustment of dead zone in load increase direction

[0197] Step S41: Calculation of adaptive dead zone correction term for load increase direction

[0198] In this embodiment, the power grid frequency drops and frequency deviations... The power grid requires the generating unit to increase output, the high-pressure regulating valve opens wider, and the bed temperature shows a downward trend. Preset load increase direction correction gain. Tolerance threshold for bed temperature decrease rate , prevent zero minimum value By multiplying the excess portion of the bed temperature drop rate and the reciprocal of the effective bed material pressure difference, and performing a limiting operation, the adaptive dead zone correction term for the load increase direction is obtained. The calculation formula is:

[0199] ;

[0200] Under this operating condition, the bed temperature change rate Effective bed material pressure difference Substitute the numerical values ​​into the calculation:

[0201] ;

[0202] ;

[0203] Step S42: Calculation of dead zone during load increase

[0204] The load increase dead zone for the current control cycle is obtained by adding the base dead zone to the correction term. The calculation formula is:

[0205] ;

[0206] Substituting the values, we get:

[0207] ;

[0208] When the rate of bed temperature decrease further increases and the effective bed material pressure difference further decreases, the value of the correction term increases synchronously, the dead zone of load increase expands accordingly, and the frequency regulation action suppresses further impact on bed temperature.

[0209] Step S5: Adaptive adjustment of dead zone in load reduction direction

[0210] Step S51: Calculation of adaptive dead zone correction term for load reduction direction

[0211] In this embodiment, the power grid frequency increases, and the frequency deviation increases. Furthermore, once the dead zone is exceeded, the unit needs to reduce output, the high-pressure regulating valve closes slightly, and the bed temperature tends to rise. The preset load reduction direction correction gain is used. Tolerance threshold for bed temperature rise rate , prevent zero minimum value By multiplying the excess portion of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference, and performing a limiting operation, the adaptive dead zone correction term for the load reduction direction is obtained. The calculation formula is:

[0212] ;

[0213] Under this operating condition, the bed temperature change rate Effective bed material pressure difference Substitute the numerical values ​​into the calculation:

[0214] ;

[0215] ;

[0216] Step S52: Calculation of load reduction dead zone

[0217] The load reduction dead zone for the current control cycle is obtained by subtracting the correction term from the base dead zone and comparing it with the preset minimum dead zone limit, taking the larger value. The calculation formula is:

[0218] ;

[0219] Substituting the values, we get:

[0220] ;

[0221] When the rate of increase in bed temperature further increases and the effective bed material pressure difference further decreases, the value of the correction term increases synchronously, the dead zone of load reduction shrinks accordingly, making it easier to trigger load reduction frequency regulation and assisting the bed temperature to drop quickly.

[0222] Step S6: Dead Zone Limiting, Speed ​​Limiting, and Smoothing

[0223] Step S61: Dead Zone Amplitude Limiting

[0224] The above calculated load increase dead zone Load reduction dead zone Limit at Right now Within the interval; in this embodiment, , All values ​​are within the limit range and no additional limit is required.

[0225] Step S62: Dead Zone Increment Rate Limit

[0226] Rate limiting is applied to the dead zone increment between adjacent control cycles, with a maximum allowable change per second set to [value missing]. In this embodiment, the dead zone increment for load increases in adjacent cycles is: The corresponding rate of change If the limit is exceeded, proceed as follows: Speed ​​limit, maximum increment per cycle is After speed limit, the dead zone for increasing load is The load reduction dead zone increment is The corresponding absolute value of the rate of change is If the limit is exceeded, proceed as follows: Speed ​​limit, maximum reduction per cycle is The dead zone for load reduction after speed limit is .

[0227] Step S63: First-order inertial smoothing

[0228] Set the smoothing time constant. Combined with control cycle Calculate the smoothing coefficient The calculation formula is:

[0229] ;

[0230] Substituting the values, we get:

[0231] ;

[0232] Smoothing is performed on the load increase and decrease dead zones separately to obtain the final load increase dead zone used for logical judgment. and the final load reduction dead zone The calculation formula is:

[0233] ;

[0234] ;

[0235] In this embodiment, the smoothing dead zone of the previous cycle , Substituting the values ​​into the speed limit, we get:

[0236] ;

[0237] ;

[0238] Step S7: Primary frequency regulation trigger judgment and load increment calculation

[0239] Step S71: Frequency Deviation Calculation

[0240] The frequency deviation is obtained by subtracting the real-time frequency of the power grid from the rated frequency. The calculation formula is:

[0241] ;

[0242] In this embodiment, the real-time frequency of the power grid under load increase conditions Substituting, we get:

[0243] ;

[0244] Real-time frequency of power grid under load reduction conditions Substituting, we get:

[0245] ;

[0246] Step S72: Frequency modulation trigger judgment and effective deviation calculation

[0247] Load increase trigger judgment: when At that time, the direction of load increase is determined by primary frequency regulation triggering, and the effective deviation is... The calculation formula is:

[0248] ;

[0249] Under the load increase condition in this embodiment , , This will not trigger frequency regulation for increased load; if the grid frequency drops to , , , Still not triggered; if the frequency drops to , , , Correction here: Frequency deviation is defined as... ,when , The load increase trigger condition is When the frequency deviation is less than the negative final load increase dead zone, the load increase is determined to be triggered, i.e. ,correspond This means that the power grid frequency is higher than the rated value.

[0250] Grid frequency , Not satisfied When the power grid frequency , ,satisfy Determine the direction of load increase and trigger the frequency regulation once, then calculate the effective deviation:

[0251] ;

[0252] Load reduction trigger judgment: when At that time, the direction of load reduction is determined by primary frequency regulation triggering, and the effective deviation is... The calculation formula is:

[0253] ;

[0254] In this embodiment, under load reduction conditions, the grid frequency... , , ,satisfy Determine the direction of load reduction and trigger the frequency regulation once, then calculate the effective deviation:

[0255] ;

[0256] If the frequency deviation is within Within the interval, the frequency modulation does not operate, and the effective deviation is set to zero.

[0257] Step S73: Calculation of primary frequency regulation load increment

[0258] The primary frequency regulation load increment is obtained through proportional calculation using the effective deviation, speed regulation inequality rate, and rated power. The calculation formula is:

[0259] ;

[0260] Under load-triggered conditions, , , , Substituting, we get:

[0261] ;

[0262] When load increase is triggered, the frequency deviation is negative, the effective deviation is negative, and the load increment is positive. The corrected frequency deviation is defined as follows: Finally, the calculation for the increased load condition was obtained. The corresponding unit increases its output. .

[0263] Under load reduction triggering conditions, Substituting, we get:

[0264] ;

[0265] When load reduction is triggered, the load increment is negative, and the corresponding unit reduces its output. .

[0266] Step S74: Load Increment Limiting and Speed ​​Limiting

[0267] The preset primary frequency regulation load increment amplitude is limited to the rated power. ,Right now The load change rate is limited to In this embodiment, both the increase and decrease in load are within the limit range, requiring no additional limiting, and are executed according to the calculated values.

[0268] Step S8: Instruction Execution and Closed-Loop Adaptive Adjustment

[0269] The primary frequency regulation load increment, after being limited in amplitude and speed, is algebraically superimposed with the current unit load command to form a total load command, which is then sent to the turbine digital electro-hydraulic control system (DEH).

[0270] The DEH system adjusts the opening of the high-pressure regulating valve according to the total load command, and achieves rapid frequency regulation response of the unit power by changing the steam flow rate;

[0271] While the frequency modulation action is being executed, the DCS continues to... Periodically collect operating parameters such as bed temperature, bed pressure, and power grid frequency, and repeatedly execute the calculation process from step S2 to step S7 to enable the load increase and decrease dead zone to achieve closed-loop adaptive adjustment based on the real-time bed temperature and bed material inventory status of the unit.

[0272] When the bed temperature change rate recovers to within the tolerance threshold, or the effective bed material pressure difference rebounds, the adaptive dead zone correction term for the load increase direction is applied. Gradually decrease, and the load increase dead zone gradually recedes back to the basic dead zone. Nearby; Adaptive dead zone correction term for load reduction direction Synchronous reduction, the load reduction dead zone is restored to the basic dead zone. A dynamic balance is achieved between the primary frequency regulation response capability of the power grid and the combustion safety of the CFB boiler.

[0273] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0274] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for adaptive adjustment of primary frequency regulation dead zone in thermal power units, characterized in that, Includes the following steps: Step S1: Synchronously collect grid frequency, original bed temperature, original bed pressure difference signal, actual power generation of the unit, main steam pressure, and comprehensive valve position command of high pressure regulating valve through the distributed control system, and retrieve the set speed regulation inequality rate and rated power of the unit. Step S2: Perform first-order inertial filtering on the original bed temperature to obtain the filtered bed temperature; calculate the bed temperature change rate using the filtered bed temperatures of adjacent periods and limit the rate of bed temperature change; perform moving average filtering on the original bed pressure difference signal to obtain the average bed pressure difference; determine the air distribution plate pressure drop corresponding to the average bed pressure difference using the cold-calibrated air distribution plate resistance curve; compare the average bed pressure difference after deducting the air distribution plate pressure drop with the preset minimum fluidization pressure difference lower limit and take the larger value to obtain the effective bed material pressure difference that characterizes the bed material inventory online; Step S3: Set the basic symmetric dead zone limit value, decouple the dead zones in the load increase direction and the load decrease direction, and take the initial load increase dead zone and the initial load decrease dead zone as the basic symmetric dead zone limit value. Step S4: Under the condition that the frequency deviation is negative, the adaptive dead zone correction term in the load increase direction is obtained by multiplying the excess portion of the bed temperature drop rate and the reciprocal of the effective bed material pressure difference and using a limiting operation; the load increase dead zone is obtained by adding the basic dead zone to the adaptive dead zone correction term in the load increase direction. Step S5: Under the condition that the frequency deviation is positive and exceeds the dead zone, the adaptive dead zone correction term in the load reduction direction is obtained by multiplying the excess part of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference and using the amplitude limiting operation. The load reduction dead zone is obtained by subtracting the adaptive dead zone correction term in the load reduction direction from the basic dead zone and comparing it with the preset minimum dead zone limit and taking the larger value. Step S6: Perform amplitude limiting and incremental rate limiting on the load increase dead zone and the load decrease dead zone, and then perform first-order inertial smoothing on the two dead zones after speed limiting to obtain the final load increase dead zone and the final load decrease dead zone for logical judgment. Step S7: Obtain the frequency deviation by subtracting the collected grid frequency from the rated frequency; when the frequency deviation is less than the negative final load increase dead zone, determine that the primary frequency regulation in the load increase direction is triggered, and obtain the effective deviation by adding the frequency deviation to the final load increase dead zone; when the frequency deviation is greater than the final load decrease dead zone, determine that the primary frequency regulation in the load decrease direction is triggered, and obtain the effective deviation by subtracting the frequency deviation from the final load decrease dead zone; obtain the primary frequency regulation load increment by proportional calculation using the effective deviation, speed regulation inequality rate, and rated power, and limit the amplitude and load change rate of the primary frequency regulation load increment; Step S8: The primary frequency regulation load increment processed by amplitude and speed limiting is algebraically superimposed with the current unit load command to form a total load command, which is then sent to the turbine digital electro-hydraulic control system to adjust the opening of the high-pressure regulating valve and achieve power response. While the action is being executed, operating parameters are continuously collected, filtered, and returned to step S2, so that the load increase dead zone and load decrease dead zone are adaptively adjusted in a closed loop according to the real-time status of the unit.

2. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Obtain the power grid frequency using a turbine speed probe or synchronous phasor measurement device. The rated frequency is denoted as [missing information]. ; Step S12: The original bed temperature is obtained by measuring the initial bed temperature using at least three thermocouples in the lower part of the dense phase zone of the circulating fluidized bed boiler, and by taking the arithmetic mean after removing outliers. ; Step S13: Obtain the original bed differential pressure signal using the differential pressure transmitters at the upper and lower parts of the dense phase region. ; Step S14: Collect the actual power output of the generating unit Main steam pressure High-pressure regulating valve integrated valve position command And retrieve the speed unequalization rate that has been set in the distributed control system. and the rated power of the unit .

3. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Suppress high-frequency noise introduced by fuel fluctuations and fluidization disturbances through first-order inertial filtering, using the current original bed temperature. Compared with the previous cycle filter value Weighted values ​​are applied to obtain the filtered bed temperature. The calculation formula is: ； In the formula, The filter bed temperature for the current control cycle. The filter bed temperature from the previous control cycle. The original bed temperature collected during the current control cycle. These are the filter coefficients; filter coefficients By filtering time constant and control cycle Determined, using relational expressions Perform calculations. Hold for 3 to 5 seconds; Step S22: Calculate the bed temperature change rate using the filtered bed temperature of adjacent periods, and obtain the dynamic trend of bed temperature change using a differential formula with amplitude limiting. The calculation formula is: ； In the formula, The rate of change of bed temperature during the current control cycle. The filter bed temperature for the current control cycle. The filter bed temperature from the previous control cycle. To control the cycle, the calculated bed temperature change rate is rate-limited, and abrupt changes exceeding 10 K / min are eliminated. Step S23: Process the raw bed pressure difference signal using a moving average filter. The average bed pressure difference was obtained using a window duration of 10 seconds. ; Step S24: Determine the pressure drop of the air distribution plate corresponding to the average bed pressure difference using the cold-calibrated air distribution plate resistance curve. ; Step S25: Compare the average bed pressure difference after deducting the pressure drop from the air distribution plate with the preset minimum fluidization pressure difference lower limit. By comparing and selecting the larger value, the effective bed material pressure difference, which represents the bed material inventory online, is obtained. The calculation formula is: ； In the formula, For effective bed material pressure differential, The average bed pressure difference is the result of moving average filtering. The pressure drop of the air distributor is determined from the average bed pressure difference using the cold-calibrated air distributor resistance curve. The lower limit constant of the pressure differential required to maintain minimum fluidization; effective bed pressure differential. The system reflects the bed material inventory level online; the lower the pressure differential, the less bed material is in stock.

4. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S3 includes the following steps: Step S31: Based on the primary frequency regulation technical standards of the power grid and considering the combustion characteristics of the circulating fluidized bed boiler, set the basic symmetrical dead zone limit value. ; Step S32: Decouple the dead zones in the load increase direction and the load decrease direction, and set the initial load increase dead zone. With initial load reduction dead zone All are taken as the basic symmetric dead zone limit value. .

5. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S4 includes the following steps: Step S41: In frequency deviation Under certain operating conditions, the power grid requires the unit to increase its output, causing the high-pressure regulating valve to open wider, resulting in a decrease in the bed temperature in the dense phase zone of the boiler. When the bed temperature decrease rate is too high and the bed material inventory is low, an adaptive dead zone correction term for the load increase direction is obtained by multiplying the excess portion of the bed temperature decrease rate with the reciprocal of the effective bed material pressure difference and performing a limiting operation. The calculation formula is: ； In the formula, For the adaptive dead zone correction term in the direction of load increase, To correct the gain in the direction of load increase, The effect of a single frequency modulation action on the bed temperature drop is preset. The bed temperature change rate obtained in step S22; This represents the tolerance threshold for the rate of bed temperature decrease. ; This represents the absolute value of the rate of decrease in bed temperature only. Exceeding the tolerance threshold The value is positive if it is positive, otherwise it is zero. The effective bed material pressure difference obtained in step S25; It is a very small positive number, used to prevent division from being meaningless when the effective bed material pressure difference is zero; Step S42: Obtain the load increase dead zone for the current control cycle by adding the base dead zone to the correction term using an addition operation. The calculation formula is: ； In the formula, This is the load increase dead zone for the current control cycle. This is the initial load increase dead zone. The adaptive dead zone correction term for the load increase direction obtained in step S41; when the effective bed material pressure difference... Smaller and the rate of bed temperature drop exceeds the tolerance threshold At that time, the correction item As the value increases, the load dead zone increases. The corresponding expansion.

6. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S5 includes the following steps: Step S51: In frequency deviation Furthermore, when operating outside the dead zone, the unit needs to reduce output, the high-pressure regulating valve closes slightly, and the bed temperature rises. When the bed temperature rises rapidly and the bed material inventory is low, the adaptive dead zone correction term for the load reduction direction is obtained by multiplying the excess portion of the bed temperature rise rate and the reciprocal of the effective bed material pressure difference with a limiting operation. The calculation formula is: ； In the formula, For the adaptive dead zone correction term in the load reduction direction, To correct the gain in the direction of load reduction, ; This represents the tolerance threshold for the rate of bed temperature rise. ; This indicates that only when the bed temperature rises at a certain rate Exceeding the tolerance threshold The value is positive if it is positive, otherwise it is zero. Step S52: Subtract the correction term from the base dead zone and perform maximum limit calculation with the preset minimum dead zone. By comparison, the dead zone in the load reduction direction can be obtained. The calculation formula is: ； In the formula, This is the load reduction dead zone for the current control cycle. The minimum allowable dead zone limit, This is the initial deload dead zone; when the bed temperature rise rate exceeds the tolerance threshold. And effective bed material pressure difference When smaller, the correction term Increase, reduce load dead zone The corresponding reduction makes it easier to trigger the primary frequency regulation in the direction of load reduction, and assists the bed temperature to drop by prioritizing the reduction of unit output.

7. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S6 includes the following steps: Step S61: Apply the load increase dead zone obtained in step S42 and the load reduction dead zone obtained in step S52 Limit at Within the interval, in the formula, The minimum allowable dead zone limit, The maximum allowable dead zone limit, Set the frequency to 0.1Hz or according to the unit's safety documentation; Step S62: Rate limit the dead zone increment of adjacent control cycles; Step S63: Based on the amplitude and speed limits, a first-order inertial smoothing process is applied, and the smoothing dead zone of the previous cycle and the dead zone after the speed limit in this cycle are weighted to obtain the final load increase dead zone used for logical judgment. and load reduction dead zone The smoothing formula is as follows: ； ； In the formula, , These are the final load increase dead zone and the final load decrease dead zone after smoothing the current control cycle; , These are the final load increase dead zone and the final load decrease dead zone of the previous control cycle, respectively. , These are the load increase dead zone and load decrease dead zone after amplitude and rate limits are applied during the current control cycle; The smoothing coefficient is determined by the smoothing time constant. and control cycle Determined, using relational expressions Perform the calculation.

8. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S7 includes the following steps: Step S71: By collecting the power grid frequency With rated frequency The frequency deviation is obtained by using interpolation calculation. The formula is as follows: ； In the formula, For frequency deviation, For the rated frequency, The power grid frequency collected in step S1; Step S72: When the frequency deviation Less than the negative final load dead zone At that time, the direction of load increase is determined by primary frequency regulation triggering. By using directional addition to calculate the frequency deviation and the final load increase dead zone, the effective deviation amount for crossing the dead zone is obtained. The formula is as follows: ； In the formula, This is the effective deviation used to calculate the load increment. For frequency deviation, This is the final load increase dead zone obtained in step S63; When frequency deviation Greater than the final load reduction dead zone At that time, the direction of load reduction is determined by primary frequency regulation triggering. The effective deviation is obtained by subtraction between the frequency deviation and the final load reduction dead zone. The formula is as follows: ； If frequency deviation In Within the range, if the frequency modulation does not operate, the effective deviation is... Set to zero; Step S73: Using the effective deviation amount Speed ​​unequalization and rated power The primary frequency regulation load increment is obtained by using proportional calculation. The formula is as follows: ； In the formula, For primary frequency regulation load increment, For the rated frequency, For speed unequal distribution, The rated power of the unit; frequency deviation when triggered by load increase. Negative, effective deviation Negative, primary frequency regulation load increment A positive value corresponds to an increase in unit load; when a load reduction is triggered, the frequency deviation... If positive, the effective deviation is... Positive, primary frequency regulation load increment A negative value corresponds to a reduction in the unit load; Step S74: Calculate the generated primary frequency regulation load increment. Implement amplitude limits and load change rate limits.

9. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, Step S8 includes the following steps: Step S81: The primary frequency regulation load increment processed by step S7 (amplitude and speed limiting) is... The current unit load command is algebraically superimposed to form a total load command, which is then transmitted to the turbine digital electro-hydraulic control system. Step S82: The turbine digital electro-hydraulic control system adjusts the opening of the high-pressure regulating valve according to the total load command to achieve primary frequency regulation response of the power; Step S83: While the action is being executed, continuously collect and filter the bed temperature and bed pressure operating parameters, and return to step S2.

10. The adaptive adjustment method for primary frequency regulation dead zone of a thermal power unit according to claim 1, characterized in that, In step S8, when the bed temperature change rate recovers to within the tolerance threshold or the effective bed material pressure difference rebounds, the adaptive dead zone correction term in the load increase direction... Gradually decrease, load increase dead zone Gradually revert to the base dead zone value Nearby; Adaptive dead zone correction term in the direction of load reduction Consequently, the load reduction dead zone decreases. Restore to base dead zone value .

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