Auxiliary frequency modulation control method and system for thermal power generating unit

Abstract

The invention relates to the technical field of data acquisition control, in particular to an auxiliary frequency modulation control method and system for a thermal power generating unit, and the method specifically comprises the steps: calculating the frequency deviation fluctuation degree of a power grid frequency through the deviation degree of the power grid frequency and a power grid power frequency, and the random degree and frequency degree of deviation; determining an adjustment coefficient of a frequency modulation dead zone through the charge state of flywheel energy storage and the change stability degree of the flywheel rotating speed in combination with the frequency deviation fluctuation degree, and adjusting a preset reference frequency deviation through the adjustment coefficient so as to determine a self-adaptive frequency modulation dead zone. Power grid frequency auxiliary frequency modulation control is carried out by adopting a self-adaptive frequency modulation dead zone interval, and the flywheel energy storage auxiliary frequency modulation control performance is improved; the problem that accurate frequency modulation control is difficult to realize in a large-scale new energy grid-connected scene due to the fact that a frequency modulation dead zone is usually set as a fixed value at present is avoided, and the stability and reliability of auxiliary frequency modulation control of the thermal power generating unit are improved.

Description

Technical Field

[0001] This application relates to the field of data acquisition and control technology, specifically to an auxiliary frequency regulation control method and system for thermal power units. Background Technology

[0002] With the rapid development of the economy and society, the large-scale grid connection of new energy sources such as wind power and solar power has caused large fluctuations in grid frequency. The intermittency and uncertainty inherent in new energy sources pose a serious challenge to grid frequency security. Grid frequency fluctuations will cause frequent frequency regulation actions of thermal power units, which will accelerate the aging of the units. Frequency regulation control of thermal power units refers to the automatic response of the generator unit's speed regulation system when the power system frequency deviates from the dead zone frequency, adjusting the active power output of the unit to restore the frequency to the dead zone. Due to the large inertia and slow response of thermal power units, energy storage is usually used to assist in the frequency regulation control of the units. Flywheel energy storage to assist in the frequency regulation of thermal power units is one of the commonly used auxiliary frequency regulation control methods, which can effectively improve the frequency regulation performance of the units.

[0003] To ensure the stable operation of flywheel energy storage systems, a frequency dead zone is typically set to prevent unnecessary charging and discharging actions caused by minor fluctuations in the grid frequency. Currently, the frequency dead zone range is usually set to a fixed value. Under the influence of large-scale renewable energy grid integration, grid frequency fluctuations are relatively large. If the frequency dead zone range is set too small, even minor fluctuations in the grid frequency will increase the triggering frequency of the frequency regulation control system, reduce the balance of the power generation system, and affect the service life of thermal power units. If the frequency dead zone range is set too large, even significant fluctuations in the grid frequency will prevent the auxiliary frequency regulation control system from responding in a timely manner, potentially leading to major accidents. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide an auxiliary frequency regulation control method and system for thermal power units, the specific technical solution of which is as follows: In a first aspect, embodiments of this application provide an auxiliary frequency regulation control method for thermal power units, the method comprising the following steps: Obtain the grid frequency and flywheel speed of the flywheel energy storage system at various times; Based on the characteristics of power grid frequency fluctuations and the flywheel speed, the frequency regulation dead zone is adaptively set, specifically as follows: (1) Obtain the deviation between each power grid frequency and the power grid frequency, and statistically analyze the distribution of non-zero elements in all the deviations in different data intervals to determine the overall fluctuation amplitude characteristic value of the power grid frequency. Combine the frequency and randomness of the non-zero elements in all the deviations to determine the frequency deviation fluctuation of the power grid frequency. (2) Calculate the state of charge of the flywheel energy storage at each time by the flywheel speed at each time; based on the degree of deviation of the state of charge from the standard state of charge and the stability of the flywheel speed change, and in combination with the frequency deviation fluctuation, determine the adjustment coefficient of the frequency dead zone interval; (3) The preset reference frequency deviation is adjusted by the adjustment coefficient to obtain the maximum frequency deviation, so as to determine the adaptive frequency modulation dead zone interval; An adaptive frequency regulation dead zone is used for auxiliary frequency regulation control of thermal power units.

[0005] In one embodiment, the process of obtaining the fluctuation amplitude feature value is as follows: The deviation is specifically the difference between each power grid frequency and the power grid operating frequency; The sequence of differences at all times is denoted as the frequency deviation sequence. A small deviation threshold is set to filter the non-zero elements in the frequency deviation sequence. The number of filtered non-zero elements in different data intervals is counted to determine the overall fluctuation amplitude characteristic value of the power grid frequency.

[0006] In one embodiment, the step of setting a small deviation threshold to filter non-zero elements in the frequency deviation sequence specifically involves: Elements whose absolute values ​​in the frequency deviation sequence are less than or equal to the threshold are filtered out, and elements whose absolute values ​​are greater than the threshold are obtained as the filtered non-zero elements.

[0007] In one embodiment, the process of obtaining the fluctuation amplitude feature value is as follows: Get the elements whose absolute value is greater than the preset reference frequency deviation among the filtered non-zero elements, and record the product of the mean of the absolute values ​​of all the corresponding elements and the corresponding number of elements as the first product; Get the elements whose absolute value is less than or equal to the preset reference frequency deviation among the filtered non-zero elements, and record the product of the mean of the absolute values ​​of all the corresponding elements and the number of the corresponding elements as the second product; The fluctuation amplitude characteristic value is directly proportional to the second product and inversely proportional to the first product.

[0008] In one embodiment, the process of obtaining the frequency deviation fluctuation is as follows: Obtain the percentage of the filtered non-zero elements in the frequency deviation sequence; obtain the permutation entropy of the elements in the frequency deviation sequence; The frequency deviation fluctuation of the power grid frequency is determined based on the fluctuation amplitude characteristic value, the proportion, and the arrangement entropy.

[0009] In one embodiment, the expression for the frequency deviation fluctuation is: ; In the formula, The frequency deviation fluctuation of the power grid frequency is represented by 'a', where 'a' is the proportion, 'b' is the permutation entropy, and 'P' is the characteristic value of the fluctuation amplitude. These are the preset error parameters.

[0010] In one embodiment, the process of obtaining the adjustment coefficient is as follows: Obtain the standard deviation c of the first-order difference sequence of the flywheel speed time series; calculate the mean d of the difference between the state of charge of the flywheel energy storage and the standard state of charge at all times; when or At that time, the adjustment coefficient of the FM dead zone interval for: ; In other cases ; Wherein, P is the characteristic value of the fluctuation amplitude. The preset threshold for deviation of state of charge. This refers to the frequency deviation fluctuation of the power grid frequency. This is the normalization function.

[0011] In one embodiment, the process of obtaining the maximum frequency deviation is as follows: The adjustment coefficient is mapped to a value in the range [0,2], and the mapped value is used as the weight of the preset reference frequency deviation. The weighted result of the reference frequency deviation is used as the maximum frequency deviation.

[0012] In one embodiment, the upper limit of the adaptive frequency dead zone is the sum of the power grid frequency and the maximum frequency deviation, and the lower limit is the difference between the power grid frequency and the maximum frequency deviation.

[0013] Secondly, embodiments of this application also provide an auxiliary frequency regulation control system for thermal power units, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0014] The embodiments of this application have at least the following beneficial effects: This application calculates the frequency deviation fluctuation of the power grid frequency by considering the degree of deviation between the power grid frequency and the power grid frequency, as well as the randomness and frequency of the deviation, thus quantifying the significance of the frequency deviation fluctuation and determining the adjustment direction of the dead zone. By combining the state of charge of the flywheel energy storage and the stability of the flywheel speed changes with the frequency deviation fluctuation, an adjustment coefficient for the frequency regulation dead zone is determined. This adjustment coefficient is used to adjust the preset reference frequency deviation, thereby determining the adaptive frequency regulation dead zone. This avoids the problem that the current frequency regulation dead zone is usually set to a fixed value, making it difficult to achieve precise frequency regulation control in large-scale new energy grid-connected scenarios. The use of an adaptive frequency regulation dead zone for power grid frequency auxiliary frequency regulation control improves the performance of flywheel energy storage-assisted frequency regulation control. This application uses flywheel energy storage for auxiliary frequency regulation control and adaptively adjusts the frequency regulation dead zone in real time, avoiding the problem of frequent triggering of frequency regulation control due to an excessively small dead zone or the inability of the auxiliary frequency regulation control system to respond in a timely manner due to an excessively large dead zone, thus improving the stability and reliability of auxiliary frequency regulation control for thermal power units. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A flowchart illustrating the steps of an auxiliary frequency regulation control method for thermal power units, provided in one embodiment of this application; Figure 2 A flowchart illustrating the steps for adaptively setting the frequency modulation dead zone. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an auxiliary frequency regulation control method and system for thermal power units proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0019] The following description, in conjunction with the accompanying drawings, details the specific scheme of the auxiliary frequency regulation control method and system for thermal power units provided in this application.

[0020] Please see Figure 1 The diagram illustrates a flowchart of an auxiliary frequency regulation control method for thermal power units according to an embodiment of this application. The method includes the following steps: Step S1: Obtain the grid frequency and flywheel speed of the flywheel energy storage system at each time point.

[0021] This application analyzes a flywheel energy storage-assisted frequency regulation scenario for thermal power units. It collects grid frequency data using a synchronous phasor measurement unit (PMU) installed at the grid connection node, and collects flywheel speed data by coaxially connecting a photoelectric encoder to the flywheel shaft. The state of charge (SOC) of the flywheel energy storage is obtained based on the flywheel speed, where SOC is equal to the ratio of the square of the flywheel speed to the square of the flywheel's rated speed. It should be noted that the calculation process for SOC is publicly known.

[0022] In this embodiment, the sampling frequency of the power grid frequency is 100Hz, the sampling frequency of the flywheel speed is 1kHz, and the sampling duration is 60s. In other embodiments of this application, the implementer can set the sampling frequency of the power grid frequency and flywheel speed, as well as the sampling duration, according to the actual situation.

[0023] To avoid missing grid frequency and flywheel speed data, the collected grid frequency and flywheel speed data are used as input, and a linear interpolation method is employed to fill in the missing values, ensuring the integrity and reliability of the data acquisition. The preprocessed grid frequency, flywheel speed, and SOC are then used for further analysis. The linear interpolation method is a well-known technique, and its specific implementation will not be detailed here.

[0024] Step S2: Based on the characteristics of power grid frequency fluctuations and the flywheel speed, adaptively set the frequency dead zone interval.

[0025] Large-scale grid connection of new energy sources leads to significant grid frequency fluctuations. If the frequency regulation dead zone is set too small, even minor grid frequency fluctuations will increase the trigger frequency of the frequency regulation control system, reduce the balance of the power generation system, and affect the operating life of thermal power units. If the frequency regulation dead zone is set too large, the auxiliary frequency regulation control system may not be able to respond promptly to large grid frequency fluctuations, potentially leading to major accidents. Therefore, it is necessary to adaptively set the frequency regulation dead zone based on the characteristics of grid frequency fluctuations. Specifically: Step S21: Obtain the deviation between each power grid frequency and the power grid operating frequency, and statistically analyze the distribution of non-zero elements in all deviations in different data intervals to determine the overall fluctuation amplitude characteristic value of the power grid frequency. Combined with the frequency and randomness of the occurrence of non-zero elements in all deviations, determine the frequency deviation fluctuation of the power grid frequency.

[0026] To analyze the frequency fluctuation of the power grid, the power grid frequency (50Hz) is subtracted from the power grid frequency at each moment within the sampling period (60s) to construct a power grid frequency deviation sequence. If the power grid frequency fluctuates frequently, there will be more non-zero elements in the frequency deviation sequence. To avoid the small measurement error caused by sampling noise leading to an excessive number of non-zero elements, a small deviation threshold is set to filter out noise non-zero elements. The small deviation threshold range is 0-0.003Hz, and in this embodiment, the threshold value is 0.001Hz. In other embodiments of this application, the implementer can set the threshold according to the actual situation. Elements whose absolute values ​​in the frequency deviation sequence are less than or equal to the threshold are filtered out. Elements whose absolute values ​​in the frequency deviation sequence are greater than the threshold are recorded as usable non-zero elements, and the number of usable non-zero elements in the frequency deviation sequence is counted. The ratio of the number of usable non-zero elements in the frequency deviation sequence to the total number of elements is calculated and recorded as the first ratio. The first ratio reflects the frequency of power grid frequency deviation under the influence of new energy grid connection. The larger the first ratio, the more frequent the power grid frequency fluctuation.

[0027] Due to the intermittency and uncertainty of new energy sources, grid frequency fluctuations are random. Therefore, the arrangement of elements in the grid frequency deviation sequence is random and irregular. The permutation entropy of the frequency deviation sequence is calculated, where the embedding dimension is set to 5 and the time delay to 1. This permutation entropy reflects the degree of randomness in the arrangement of elements in the grid frequency deviation sequence under the influence of new energy grid connection. A higher permutation entropy indicates a more random arrangement of elements in the grid frequency deviation sequence under the influence of new energy grid connection, meaning a greater randomness in grid frequency fluctuations. It should be noted that the values ​​of the embedding dimension and time delay can be set by the implementer according to actual conditions; this application does not impose specific restrictions.

[0028] The first ratio and permutation entropy can only reflect the frequency and randomness of the fluctuations in the power grid frequency relative to the power frequency, but cannot reflect the overall amplitude of the frequency fluctuations. It is difficult to distinguish whether the power grid frequency fluctuations are small or large, and therefore difficult to determine the adjustment direction of the dead zone interval. To analyze the amplitude characteristics of the power grid frequency fluctuations, the absolute values ​​of the available non-zero elements in the frequency deviation sequence are compared with the reference frequency deviation. Since the power grid frequency fluctuations are generally within 50 ± 0.033 Hz, the reference frequency deviation is set to 0.033 Hz in this embodiment. Elements in the frequency deviation sequence whose absolute values ​​of available non-zero elements are greater than the reference frequency deviation are selected. The number of selected elements is denoted as... , will this The mean of the absolute values ​​of the available non-zero elements is denoted as . ; Select elements from the frequency deviation sequence whose absolute values ​​of non-zero elements are less than or equal to the reference frequency deviation, where the number of selected elements is denoted as . , will this The mean of the absolute values ​​of the available non-zero elements is denoted as . The available non-zero elements refer to elements whose absolute value is greater than the threshold value.

[0029] Furthermore, the characteristic value P of the fluctuation amplitude is calculated, and its expression is: In the formula, This represents the error parameter. To avoid the denominator being 0, which would render the calculation meaningless, this embodiment uses a value of 0.005. In other embodiments of this application, the implementer can set the value according to the actual situation. The value of P is determined by adding an error parameter of the same size to the molecule to ensure that there exists a case where P equals 1.

[0030] P reflects the significance of small fluctuations in the power grid frequency. A larger P value (greater than 1) indicates a higher significance of small fluctuations, requiring a larger dead zone to prevent excessive triggering of the frequency regulation control system. If P equals 1, the power grid frequency fluctuations are relatively balanced, allowing the existing dead zone to be maintained. Conversely, a smaller P value (greater than or equal to 0 but less than 1) indicates larger fluctuations in the power grid frequency, requiring a smaller dead zone to improve the timely response speed of the frequency regulation control system. The first product, This is the second product.

[0031] Based on the above analysis, the frequency deviation fluctuation of the power grid is calculated to characterize the significance of the frequency deviation fluctuation of the power grid under the influence of new energy grid integration. The expression for the frequency deviation fluctuation is as follows: ; In the formula, The frequency deviation fluctuation of the power grid frequency is represented by 'a', where 'a' is the first ratio, 'b' is the permutation entropy, and 'P' is the fluctuation amplitude characteristic value. This represents the error parameter. Wherein, The purpose is to avoid the denominator being 0, which would render the calculation meaningless. In this embodiment... The value is 0.05. In other embodiments of this application, the implementer may set the value according to the actual situation. The value of .

[0032] It should be noted that the sign of A only indicates the direction of the dead zone interval that needs to be adjusted (increased or decreased), and does not reflect the magnitude of the value. The higher the significance of the power grid frequency being a small fluctuation, the larger the dead zone interval needs to be adjusted upwards. This indicates that the power grid frequency fluctuations are relatively balanced, maintaining the original frequency regulation dead zone. This indicates that the greater the fluctuation range of the power grid frequency, the smaller the dead zone interval needs to be adjusted. Therefore, the value of A is negative.

[0033] First ratio The larger the entropy of the arrangement The larger the value, the greater the fluctuation in the power grid frequency deviation. If the fluctuation amplitude characteristic... The larger the value and the greater than 1, the higher the significance of the frequency deviation fluctuation being a small fluctuation amplitude. Therefore, the frequency deviation fluctuation degree... The larger the value, the more significant the fluctuation in grid frequency deviation under the influence of new energy grid connection; if the fluctuation amplitude characteristics are... The smaller the value (greater than 0 and less than 1), the higher the significance of the frequency deviation fluctuation, indicating a larger fluctuation range. Therefore, the frequency deviation fluctuation... The larger the value, the greater the fluctuation of the grid frequency deviation under the influence of new energy grid connection.

[0034] Step S22: Calculate the state of charge of the flywheel energy storage at each time by using the flywheel speed at each time; based on the degree of deviation of the state of charge from the standard state of charge and the stability of the flywheel speed change, and in combination with the frequency deviation fluctuation, determine the adjustment coefficient of the frequency tuning dead zone.

[0035] Power grid frequency fluctuations typically require flywheel energy storage to assist in frequency regulation. If the frequency deviation is less than the lower limit of the dead zone, the flywheel converts kinetic energy into electrical energy, and the flywheel speed decreases. If the frequency deviation is greater than the upper limit of the dead zone, the flywheel converts electrical energy into flywheel kinetic energy, and the flywheel speed increases. As the flywheel speed increases, frequent fluctuations in power grid frequency will lead to frequent fluctuations in flywheel speed and flywheel SOC.

[0036] To analyze the fluctuation characteristics of flywheel speed, the flywheel speed at each moment within the sampling period (60s) was obtained. To obtain the fluctuation characteristics of flywheel speed per unit time, a time series sequence of flywheel speed was constructed, and the standard deviation of the first difference sequence of the flywheel speed time series was calculated. This reflects the degree of fluctuation of flywheel speed under the influence of new energy grid connection. The larger the standard deviation, the more frequent and greater the fluctuation of flywheel speed under the influence of new energy grid connection.

[0037] Each change in flywheel speed causes fluctuations in the State of Charge (SOC) of flywheel energy storage. Generally, when the SOC is around 0.5, the flywheel energy storage auxiliary frequency regulation efficiency is the highest, and the frequency regulation sensitivity is high, which can cope with frequent responses when the dead zone is small. When the SOC is close to the upper or lower limit of SOC, the flywheel energy storage frequency regulation efficiency is low, and the charging / discharging frequency should be reduced. By increasing the dead zone, time should be allowed for the flywheel energy storage to recover to a better SOC state.

[0038] To analyze the State of Charge (SOC) of flywheel energy storage, the deviation of the SOC from the standard SOC at each moment is calculated. This deviation is determined based on the principle of rate of change. Specifically, taking the i-th moment in the sampling period as an example, the SOC value at the i-th moment is... The standard SOC is s, and the degree of deviation is Next, the mean of the deviation at all times during the sampling period is calculated and denoted as the SOC deviation. This reflects the significance of the flywheel energy storage's SOC deviating from the standard SOC under the influence of new energy grid connection. The larger the SOC deviation, the higher the significance of the flywheel energy storage's SOC deviating from the standard SOC under the influence of new energy grid connection. The standard SOC is typically set to 0.5; therefore, in this embodiment, the standard SOC value is set to 0.5. In other embodiments of this application, the implementer can set the standard SOC value according to the actual situation.

[0039] The greater the fluctuation in flywheel speed, the greater the fluctuation in the State of Charge (SOC) of the flywheel energy storage, which in turn leads to an increase in SOC deviation, exceeding the SOC deviation threshold. In this embodiment, the threshold value is... The value is 0.15. In other embodiments of this application, the implementer can set the threshold according to the actual situation. The value of dead zone should be considered. If the SOC deviation exceeds the threshold, the flywheel energy storage frequency regulation efficiency is low, and the dead zone interval should be increased to reduce the charging / discharging frequency. If the SOC deviation is below the threshold, the flywheel energy storage frequency regulation efficiency is high, and the dead zone interval should be reduced to meet the frequent response requirements of the grid frequency regulation. If the dead zone adjustment direction determined based on frequency deviation fluctuations is consistent with the dead zone adjustment direction determined based on SOC deviation, the dead zone adjustment amplitude should be further increased; conversely, the dead zone adjustment amplitude should be appropriately reduced.

[0040] Based on the above analysis, the adjustment coefficient of the FM dead zone is calculated, which characterizes the adjustment range for the adaptive dead zone: when or hour, ; In other cases .

[0041] in, This represents the adjustment factor for the FM dead zone. The frequency deviation fluctuation of the grid frequency is represented by , c is the standard deviation of the first-order difference sequence of the flywheel speed time series, and d is the SOC deviation of the flywheel energy storage. The SOC deviation threshold is... This is the normalization function.

[0042] In this embodiment, the normalization function used is maximum-minimum normalization, calculated based on data from all sampling durations within a recent period. The value is normalized, and the size of the most recent period can be set by the implementer; in this embodiment, the most recent 30 minutes are selected. In other embodiments of this application, the implementer may also use other normalization functions. The value is normalized.

[0043] The relationship between the positive and negative values ​​of and To maintain consistency, its positive or negative sign only indicates the direction of adjustment within the dead zone. The greater the frequency deviation fluctuation, the higher the standard deviation of the flywheel speed. The larger the value of A, the greater the SOC deviation of the flywheel energy storage will be if it exceeds the threshold and A is positive, or if it is less than the threshold and A is negative. The absolute value of the adjustment coefficient in the frequency regulation dead zone is then... The larger the value, the greater the adjustment range of the adaptive dead zone. Under other conditions, it indicates that the dead zone adjustment direction determined by the frequency deviation fluctuation is inconsistent with the dead zone adjustment direction determined by the SOC deviation, and the adjustment range should be appropriately reduced.

[0044] Step S23: Adjust the preset reference frequency deviation using the adjustment coefficient to obtain the maximum frequency deviation, thereby determining the adaptive frequency modulation dead zone interval.

[0045] Based on the above analysis, the maximum allowable frequency deviation after adaptive adjustment is calculated, representing the allowable amplitude of grid frequency fluctuation: ; In the formula, This indicates the maximum frequency deviation allowed for frequency fluctuations after adaptive adjustment. This represents the adjustment factor for the FM dead zone. Indicates the reference frequency deviation. Represents the normalization function. For adjustment coefficients, The value varies The positive and negative states change, if If it is a negative value, then The value is -1; if If it is a positive value, then The value is 1.

[0046] The positive or negative sign indicates that the frequency modulation dead zone range is increased or decreased, avoiding excessive adjustment of the reference frequency deviation. Therefore, the adaptively adjusted frequency modulation dead zone range is... 50Hz is the power grid frequency.

[0047] Step S3: Use adaptive frequency regulation dead zone interval for grid frequency assisted frequency regulation control.

[0048] The grid frequency and flywheel speed collected within the sampling period (60s) prior to the current time are obtained. The real-time adaptive frequency regulation dead zone range is then determined using the above method. The grid frequency at the current time is then acquired. If the current grid frequency is within this adaptive frequency regulation dead zone range, no auxiliary frequency regulation control of the thermal power unit is required, and the current flywheel speed is maintained. If the current grid frequency exceeds the upper limit of this adaptive frequency regulation dead zone range... If the current grid frequency is below the lower limit of the frequency regulation dead zone, then the flywheel energy storage needs to be charged to convert grid power into flywheel kinetic energy and reduce the grid frequency to the frequency regulation dead zone range. Then, the flywheel energy storage needs to be discharged to convert the flywheel kinetic energy into grid electrical energy, increasing the grid frequency to the frequency regulation dead zone range. The specific charging and discharging power of the flywheel energy storage is equal to the absolute difference between the current real-time power and the theoretical power of the thermal power unit. The real-time power is obtained by collecting the output of the thermal power unit through a power analyzer to obtain the real-time power of the grid. The theoretical power refers to the ideal power value that the unit should output after the grid frequency deviation triggers a frequency regulation. The theoretical power is calculated based on the speed unequal rate. The calculation of the theoretical power of the thermal power unit based on the speed unequal rate is a well-known technology, and the specific implementation will not be elaborated here.

[0049] The flowchart for adaptively setting the frequency modulation dead zone is as follows: Figure 2 As shown.

[0050] Based on the same inventive concept as the above method, this application embodiment also provides an auxiliary frequency regulation control system for thermal power units, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described auxiliary frequency regulation control methods for thermal power units.

[0051] In summary, this application provides an auxiliary frequency regulation control method for thermal power units. By calculating the frequency deviation fluctuation of the grid frequency based on the degree of deviation between the grid frequency and the power grid frequency, as well as the randomness and frequency of the deviation, the method quantifies the significance of the grid frequency deviation fluctuation and determines the adjustment direction of the dead zone. By combining the state of charge of the flywheel energy storage and the stability of the flywheel speed change with the frequency deviation fluctuation, the adjustment coefficient of the frequency regulation dead zone is determined. This adjustment coefficient is used to adjust the preset reference frequency deviation, thereby determining the adaptive frequency regulation dead zone. This avoids the problem that the current frequency regulation dead zone is usually set to a fixed value, making it difficult to achieve accurate frequency regulation control in large-scale new energy grid-connected scenarios. Using an adaptive frequency regulation dead zone for grid frequency auxiliary frequency regulation control improves the performance of flywheel energy storage-assisted frequency regulation control. This application uses flywheel energy storage for auxiliary frequency regulation control and adaptively adjusts the frequency regulation dead zone in real time, avoiding the problem of frequent triggering of frequency regulation control due to an excessively small dead zone or the inability of the auxiliary frequency regulation control system to respond in a timely manner due to an excessively large dead zone, thus improving the stability and reliability of the auxiliary frequency regulation control for thermal power units.

[0052] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this application. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0053] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0054] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for auxiliary frequency regulation control of thermal power units, characterized in that, The method includes the following steps: Obtain the grid frequency and flywheel speed of the flywheel energy storage system at various times; Based on the characteristics of power grid frequency fluctuations and the flywheel speed, the frequency regulation dead zone is adaptively set, specifically as follows: (1) Obtain the deviation between each power grid frequency and the power grid frequency, and statistically analyze the distribution of non-zero elements in all the deviations in different data intervals to determine the overall fluctuation amplitude characteristic value of the power grid frequency. Combine the frequency and randomness of the non-zero elements in all the deviations to determine the frequency deviation fluctuation of the power grid frequency. (2) Calculate the state of charge of the flywheel energy storage at each time by the flywheel speed at each time; based on the degree of deviation of the state of charge from the standard state of charge and the stability of the flywheel speed change, and in combination with the frequency deviation fluctuation, determine the adjustment coefficient of the frequency dead zone interval; (3) The preset reference frequency deviation is adjusted by the adjustment coefficient to obtain the maximum frequency deviation, so as to determine the adaptive frequency modulation dead zone interval; An adaptive frequency regulation dead zone is used for auxiliary frequency regulation control of thermal power units.

2. The auxiliary frequency regulation control method for thermal power units as described in claim 1, characterized in that, The process for obtaining the fluctuation amplitude characteristic value is as follows: The deviation is specifically the difference between each power grid frequency and the power grid operating frequency; The sequence of differences at all times is denoted as the frequency deviation sequence. A small deviation threshold is set to filter the non-zero elements in the frequency deviation sequence. The number of filtered non-zero elements in different data intervals is counted to determine the overall fluctuation amplitude characteristic value of the power grid frequency.

3. The auxiliary frequency regulation control method for thermal power units as described in claim 2, characterized in that, The method of setting a small deviation threshold to filter non-zero elements in the frequency deviation sequence is as follows: Elements whose absolute values ​​in the frequency deviation sequence are less than or equal to the threshold are filtered out, and elements whose absolute values ​​are greater than the threshold are obtained as the filtered non-zero elements.

4. The auxiliary frequency regulation control method for thermal power units as described in claim 2, characterized in that, The process for obtaining the fluctuation amplitude characteristic value is as follows: Get the elements whose absolute value is greater than the preset reference frequency deviation among the filtered non-zero elements, and record the product of the mean of the absolute values ​​of all the corresponding elements and the corresponding number of elements as the first product; Get the elements whose absolute value is less than or equal to the preset reference frequency deviation among the filtered non-zero elements, and record the product of the mean of the absolute values ​​of all the corresponding elements and the number of the corresponding elements as the second product; The fluctuation amplitude characteristic value is directly proportional to the second product and inversely proportional to the first product.

5. The auxiliary frequency regulation control method for thermal power units as described in claim 2, characterized in that, The process for obtaining the frequency deviation fluctuation is as follows: Obtain the percentage of the filtered non-zero elements in the frequency deviation sequence; obtain the permutation entropy of the elements in the frequency deviation sequence; The frequency deviation fluctuation of the power grid frequency is determined based on the fluctuation amplitude characteristic value, the proportion, and the arrangement entropy.

6. The auxiliary frequency regulation control method for thermal power units as described in claim 5, characterized in that, The expression for the frequency deviation fluctuation is: In the formula, The frequency deviation fluctuation of the power grid frequency is represented by 'a', where 'a' is the proportion, 'b' is the permutation entropy, and 'P' is the characteristic value of the fluctuation amplitude. These are the preset error parameters.

7. The auxiliary frequency regulation control method for thermal power units as described in claim 1, characterized in that, The process of obtaining the adjustment coefficient is as follows: Obtain the standard deviation c of the first-order difference sequence of the flywheel speed time series; calculate the mean d of the difference between the state of charge of the flywheel energy storage and the standard state of charge at all times; when or At that time, the adjustment coefficient of the FM dead zone interval for: ; In other cases ; Wherein, P is the characteristic value of the fluctuation amplitude. The preset threshold for deviation of state of charge. This refers to the frequency deviation fluctuation of the power grid frequency. This is the normalization function.

8. The auxiliary frequency regulation control method for thermal power units as described in claim 1, characterized in that, The process for obtaining the maximum frequency deviation is as follows: The adjustment coefficient is mapped to a value in the range [0,2], and the mapped value is used as the weight of the preset reference frequency deviation. The weighted result of the reference frequency deviation is used as the maximum frequency deviation.

9. The auxiliary frequency regulation control method for thermal power units as described in claim 1, characterized in that, The upper limit of the adaptive frequency modulation dead zone is the sum of the power grid frequency and the maximum frequency deviation, and the lower limit is the difference between the power grid frequency and the maximum frequency deviation.

10. An auxiliary frequency regulation control system for thermal power units, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-9.

Images