A method, apparatus, device, and medium for calculating the lowest system frequency information.

Abstract

This application provides a method, apparatus, device, and medium for calculating system minimum frequency information. The method involves obtaining the system inertia, the first frequency change rate at the moment of power disturbance occurrence, and the power system transfer function of the power system. The power disturbance is calculated based on the system inertia and the first frequency change rate. An approximate frequency curve of the system frequency deviation is determined based on the transfer function and the power disturbance. Using a bisection method, the target system minimum frequency information, including the minimum frequency value and the moment of minimum frequency, is calculated based on the approximate frequency curve and the power disturbance. This method eliminates the need for power system simulation and requires only a small amount of data to calculate the system minimum frequency information, thus improving the efficiency and convenience of the calculation.

Description

Technical Field

[0001] This application relates to the field of power system technology, specifically to a method, device, and storage medium for calculating the lowest system frequency information. Background Technology

[0002] When a power system experiences a high-power disturbance, such as the tripping of large generating units or DC blocking, the system frequency undergoes inertial response, primary frequency regulation response, secondary frequency regulation response, and tertiary frequency regulation response. The inertial response and primary frequency regulation response, with time scales on the order of seconds, determine the minimum frequency drop information. When this minimum frequency information falls below the maximum permissible frequency deviation, low-frequency load shedding will be initiated to ensure system operation, resulting in substantial economic losses and potentially even grid disconnection and major blackouts. Therefore, calculating the minimum system frequency information of the power system is crucial.

[0003] In existing technologies, the estimation of system minimum frequency information often employs artificial intelligence (AI) to modify the frequency response model, or directly uses AI to solve for the minimum frequency point. This method requires a large amount of training data; however, since high-power disturbance faults have rarely occurred, there are only a few such data points in actual systems, requiring simulations to obtain training data. Furthermore, AI suffers from poor interpretability; for severe power system faults that could potentially cause large-scale blackouts, its weak interpretability fails to provide convincing evidence and facilitate accountability. The method also has poor transferability, requiring training for each system and lacking simple transferability. Moreover, generally speaking, this method requires even more input data to achieve relatively accurate predictions.

[0004] Existing technologies have poor computational efficiency and convenience for the lowest frequency information. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a method, apparatus, device and storage medium for calculating the lowest system frequency information, which can effectively improve the calculation efficiency and convenience of the lowest system frequency information.

[0006] Firstly, this application provides a method for calculating the lowest system frequency information, including:

[0007] Obtain the system inertia, the first rate of change of frequency at the moment of power disturbance, and the transfer function of the power system;

[0008] The power disturbance of the power system is calculated based on the system inertia and the first frequency change rate.

[0009] Based on the transfer function and the power disturbance, determine the approximate frequency curve of the system frequency deviation of the power system;

[0010] According to the bisection method, the target system's minimum frequency information is obtained by calculating based on the frequency approximation curve and the power disturbance amount. The target system's minimum frequency information includes the minimum frequency value and the time of the minimum frequency.

[0011] Optionally, based on the transfer function and the power disturbance, a frequency approximation curve of the system frequency deviation of the power system is determined, including:

[0012] Based on the transfer function and the power disturbance, a basic curve of the system frequency deviation of the power system is constructed.

[0013] Based on the aforementioned basic curve, boundary conditions for the basic curve are introduced;

[0014] The undetermined parameters in the basic curve are solved by the boundary conditions to determine the approximate frequency curve.

[0015] Optionally, the method further includes:

[0016] Obtain the step response of the frequency modulation resource;

[0017] Based on the step response, determine the static gain of the frequency modulation resource;

[0018] Based on the static gain, the quasi-steady-state frequency of the power system is determined;

[0019] The boundary conditions introduced based on the base curve include:

[0020] Based on the fundamental curve and the quasi-steady-state frequency, boundary conditions for the fundamental curve are introduced.

[0021] Optionally, the method further includes: obtaining the maximum permissible frequency deviation of the system and a first parameter, wherein the first parameter is a coefficient used to calculate the initial minimum frequency point of the power system;

[0022] Then, based on the bisection method, the minimum frequency information of the target system is calculated using the approximate frequency curve and the power disturbance, including:

[0023] Based on the maximum permissible frequency deviation of the system and the first parameter, the initial minimum frequency point of the power system is determined;

[0024] Based on the initial lowest frequency point and the frequency approximation curve, calculations are performed to determine multiple first power increment information of multiple frequency modulation resources at the lowest frequency moment;

[0025] Based on multiple pieces of the first power increment information, the total power increment of the first frequency modulation resource is determined;

[0026] If the total power increment of the frequency modulation resources is greater than the power disturbance, then the minimum system frequency information is determined based on the first parameter; if the total power increment of the first frequency modulation resources is greater than the power disturbance, then the minimum system frequency information is determined based on the first parameter.

[0027] Based on the first system's lowest frequency information and the frequency approximation curve, calculations are performed to determine multiple second power increment information for multiple frequency modulation resources at the lowest frequency time;

[0028] Based on multiple pieces of the second power increment information, determine the total power increment of the second frequency modulation resource;

[0029] The minimum frequency information of the first system is updated based on the total power increment of the second frequency modulation resource and the power disturbance, thereby obtaining the minimum frequency information of the target system.

[0030] Optionally, the method further includes:

[0031] If the total power increment of the first frequency regulation resource is less than or equal to the power disturbance, then the first parameter is updated, and the step of determining the initial minimum frequency point of the power system based on the maximum allowable frequency deviation of the system and the first parameter is returned, until the total power increment of the first frequency regulation resource is greater than the power disturbance.

[0032] Optionally, the first system minimum frequency information includes the minimum frequency value and the maximum frequency value.

[0033] The first system minimum frequency information is updated based on the total power increment of the second frequency modulation resource and the power disturbance to obtain the target system minimum frequency information, including:

[0034] If the total power increment of the second frequency modulation resource is greater than the power disturbance, update the upper limit of the minimum frequency value and the minimum frequency value;

[0035] If the updated minimum frequency upper limit and the first difference between the updated minimum frequency value and the updated minimum frequency value satisfy a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

[0036] Optionally, the first system minimum frequency information includes the minimum frequency value and the lower limit of the minimum frequency value;

[0037] The first system minimum frequency information is updated based on the total power increment of the second frequency modulation resource and the power disturbance to obtain the target system minimum frequency information, including:

[0038] If the total power increment of the second frequency modulation resource is less than or equal to the power disturbance, update the minimum frequency value and the lower limit of the minimum frequency value.

[0039] If the second difference between the updated minimum frequency value and the lower limit of the updated minimum frequency value satisfies a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

[0040] Secondly, this application provides a computing device for system frequency minimum information, comprising:

[0041] The acquisition unit is used to acquire the system inertia of the power system, the first frequency change rate at the moment of power disturbance, and the transfer function of the power system.

[0042] The calculation unit is used to calculate the power disturbance of the power system based on the system inertia and the first frequency change rate.

[0043] The determining unit is used to determine the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance.

[0044] The calculation unit is also used to calculate, based on the frequency approximation curve and the power disturbance, using the bisection method to obtain the target system's minimum frequency information, which includes the minimum frequency value and the time of the minimum frequency.

[0045] Thirdly, this application provides a computing device for system frequency minimum information, comprising:

[0046] Memory, used to store computer programs;

[0047] A processor for executing a computer program stored in the memory to implement the steps of the method for calculating the lowest system frequency information as described in the first aspect.

[0048] Fourthly, this application provides a computer-readable storage medium storing a computer program that is executed by a processor to implement the steps of the method for calculating the lowest system frequency information as described in the first aspect.

[0049] As can be seen, the method, apparatus, device, and medium for calculating system minimum frequency information disclosed in this application involve obtaining the system inertia, the first frequency change rate at the time of power disturbance occurrence, and the power system transfer function of the power system; calculating the power disturbance amount of the power system based on the system inertia and the first frequency change rate; determining the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance amount; and calculating the target system minimum frequency information based on the approximate frequency curve and the power disturbance amount using a bisection method. The target system minimum frequency information includes the minimum frequency value and the time of the minimum frequency. This method eliminates the need for power system simulation and requires only a small amount of data to calculate the system minimum frequency information, thus improving the calculation efficiency and convenience. Attached Figure Description

[0050] To more clearly illustrate the technical solutions 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0051] Figure 1 This is a flowchart illustrating a method for calculating the lowest system frequency information provided in an embodiment of this application;

[0052] Figure 2 This is a schematic diagram of a system control block diagram provided in an embodiment of this application;

[0053] Figure 3 This application provides a method for... Figure 2 A simplified control block diagram;

[0054] Figure 4 This is a flowchart illustrating another method for calculating the lowest system frequency information provided in an embodiment of this application;

[0055] Figure 5 This is a schematic diagram of the structure of a computing device for system minimum frequency information provided in an embodiment of this application. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0057] To facilitate understanding of the technical solution provided in this application, the method for calculating the lowest system frequency information provided in this application will be described below with reference to the accompanying drawings. See also Figure 1 The figure is a flowchart illustrating a method for calculating the lowest system frequency information provided in an embodiment of this application. Figure 1 As shown, the method includes S101-S104.

[0058] S101: Obtain the system inertia, the first frequency change rate at the moment of power disturbance, and the transfer function of the power system.

[0059] This application does not limit the specific method of obtaining the first frequency change rate. As an example, when a power system faces a high-power disturbance, the system inertia... With no fundamental changes, this application uses the total capacity of online units as the power base value and obtains the system inertia based on the start-up and shutdown status of the units.

[0060] It is understood that the first frequency change rate is the frequency change rate at the instant the power disturbance occurs. This application does not limit the specific method of obtaining the first frequency change rate. As an example, this application can measure the frequency change rate at the instant the power disturbance occurs using a synchronous phasor measurement unit (PMU). .

[0061] This application does not limit the specific content of the transfer function; as an example, such as Figure 2 As shown, Figure 2 This application provides a schematic diagram of a system frequency control block diagram. This application can determine the system's transfer function using the system frequency control block diagram. Figure 2 In the middle, the input is a step power disturbance. This generally refers to a sudden decrease in power generation or a sudden increase in load power, so the input is negative. The output is the frequency deviation. Initial frequency deviation = 0. There are five lines in total, the first line... This refers to the transfer function of the system response. For the system's equivalent inertia, This represents the load droop factor. The second and third lines represent the transfer functions for frequency regulation of multiple renewable energy units. For the virtual inertia of new energy units, This refers to the droop control coefficient for new energy generating units. This represents the power increment of new energy generating units. The fourth and fifth rows represent the transfer functions for frequency regulation of multiple thermal power units (only two are shown in the diagram). This is the speed governor adjustment coefficient. This is the power proportionality coefficient for the high-pressure turbine. The reheater time constant is... This is the mechanical power gain coefficient. This represents the power increment of thermal power units.

[0062] As one possible implementation, this application can also simplify the system control block diagram, using the second-order transfer function corresponding to the simplified control block diagram as the transfer function of this application. For example... Figure 3 As shown, Figure 3 A method for providing an embodiment of this application Figure 2 A simplified control block diagram is presented. The frequency response model is obtained through aggregation, approximation, and transformation, where… It is the system inertia. The droop coefficient for the entire system. The gain coefficient for the power of all generating units. This represents the system's equivalent time constant. Using this simplified control block diagram, the transfer function of the power system can be directly obtained in this application.

[0063] S102: The power disturbance of the power system is calculated based on the system inertia and the first frequency change rate.

[0064] This application does not limit the specific method of calculating the power disturbance of the power system based on the system inertia and the first frequency change rate. As an example, this application can calculate it using the following formula:

[0065] ;

[0066] In the formula, This represents the power disturbance. Indicates system inertia. This represents the rate of change of the first frequency.

[0067] It is understandable that the above formula is derived from the swing equation of the power system.

[0068] The frequency curve can be described by the rocking equation:

[0069] ;

[0070] In the formula: For the system's equivalent inertia, For system frequency deviation, This represents the sum of the power increments of the primary frequency regulation resources. This represents the power disturbance faced by the system.

[0071] exist At that moment, the frequency deviation reached its lowest point. ,at this time Therefore, there is This formula can be used to determine whether the frequency has reached its lowest point. At the moment the power disturbance occurs... hour, This allows the swing equation to be transformed into a formula for calculating power disturbance.

[0072] S103: Determine the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance.

[0073] This application does not limit the specific method for determining the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance. As an example, determining the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance includes the following steps A1-A3:

[0074] A1: Based on the transfer function and the power disturbance, construct a basic curve of the system frequency deviation of the power system, the basic curve including parameters to be determined.

[0075] It is understandable that this application can determine the true curve of the system frequency deviation by using the transfer function and power perturbation:

[0076] ;

[0077] In the formula, Indicates the system frequency deviation. The droop coefficient for the entire system. The gain coefficient for the power of all generating units. The system's equivalent time constant, Let represent the overall transfer function of the system, and s be a complex number and complex frequency of the Laplace transform.

[0078] Based on the actual curve of the system frequency deviation mentioned above, its time-domain form can be directly derived as follows:

[0079]

[0080] In the formula: The time-domain form of the true curve representing the system frequency deviation. , , t represents the time variable, which can be understood as a moment in time; This is the system's equivalent time constant.

[0081] Since ω is very small, It's also relatively small, in Within the scope, for and After performing a second-order approximation and simplification, the second expression for the true frequency deviation curve can be obtained as follows:

[0082] ;

[0083] Based on the second expression of the actual frequency deviation curve mentioned above, the time-domain form of the fundamental curve can be determined as follows:

[0084] ;

[0085] In the formula These are parameters to be determined, for example, parameters to be determined for the base curve. This represents the time-domain form of the basic curve.

[0086] The complex frequency domain form of the fundamental curve is:

[0087] ;

[0088] In the formula, The fundamental curve is represented in the complex frequency domain form. It can be understood that the fundamental curve is used to approximate the true frequency response curve.

[0089] A2: Based on the aforementioned basic curve, introduce the boundary conditions for the basic curve.

[0090] This application does not limit the specific way of introducing boundary conditions based on the basic curve. As one possible implementation, the method for calculating the lowest system frequency information provided in this application also includes the following steps B1-B3:

[0091] B1: Obtain the step response of the frequency modulation resource.

[0092] Understandably, a step response can be obtained through experiments, simulations, or calculations. As an example, the formula for calculating a step response is shown below:

[0093] ;

[0094] In the formula, Represents the inverse Laplace transform. This represents the step response of frequency modulation resource i. Let represent the transfer function of the i-th frequency modulation resource. This can be understood as the transfer function of the entire system. It can be considered as multiple The sum of .

[0095] This application does not require prior knowledge. The specific form only requires obtaining the step response. The scattered points are sufficient.

[0096] B2: Based on the step response, determine the static gain of the frequency modulation resource.

[0097] It is understandable that the static gain is the final value of the step response, which can be determined by the following formula:

[0098] In the formula, This represents the static gain of the i-th unit. This represents the transfer function corresponding to the control block diagram. This represents the step response of frequency modulation resource i.

[0099] B3: Determine the quasi-steady-state frequency of the power system based on the static gain.

[0100] This application does not limit the method of determining the quasi-steady-state frequency. As an example, the formula for calculating the quasi-steady-state frequency is as follows:

[0101] ;

[0102] In the formula, Indicates the quasi-steady-state frequency. This represents the power disturbance, and i represents the i-th frequency modulation resource. Represents a set of frequency modulation resources. This represents the sum of the static gains of all frequency modulation resources.

[0103] Then, A2 introduces boundary conditions for the basic curve based on the basic curve, including: introducing boundary conditions for the basic curve based on the basic curve and the quasi-steady-state frequency.

[0104] It is understandable that there is a correlation between the quasi-steady-state frequency and the lowest frequency of the system. In overdamped systems, a value can generally be taken as... ;In the formula, Indicates the quasi-steady-state frequency. This indicates the lowest frequency value.

[0105] make The time with the lowest frequency can then be determined. ;

[0106] The boundary conditions can be as follows:

[0107]

[0108] It is understandable that the first equation represents the approximate frequency curve at the moment of minimum frequency. Frequency deviation reaches its lowest point In other words: Then substitute The first formula can be obtained by doing so. The parameters in the formula are the same as those described above, and will not be repeated here.

[0109] A3: Solve the undetermined parameters using the boundary conditions to determine the approximate frequency curve.

[0110] This application does not limit the specific method for solving the undetermined parameters through boundary conditions. As an example, an approximate solution method can be used to determine the undetermined parameters. Then, the values ​​of the undetermined parameters are substituted into the basic curve to determine an approximate frequency curve.

[0111] S104: Based on the bisection method, the minimum system frequency information is obtained by calculating the approximate frequency curve and the power disturbance amount. The minimum system frequency information includes the minimum frequency value and the time of the minimum frequency.

[0112] This application does not limit the specific method of calculation based on the frequency approximation curve and the power disturbance amount according to the bisection method. As an example, this application will also obtain the maximum permissible frequency deviation of the system and the first parameter.

[0113] Then, S104 calculates the minimum frequency information of the target system based on the frequency approximation curve and the power disturbance using the bisection method, including C1-C7:

[0114] C1: Based on the maximum permissible frequency deviation of the system and the first parameter, determine the initial minimum frequency point of the power system.

[0115] Understandably, the first parameter is a coefficient used to calculate the initial minimum frequency point of the power system, and its initial value can be 1. The maximum permissible frequency deviation of the system can be considered as an assumption, and the initial minimum frequency point of the power system determined based on the maximum permissible frequency deviation and the first parameter can also be considered as an assumption. The initial minimum frequency point can be updated through subsequent iterative calculations to determine the accurate minimum system frequency information.

[0116] As an example, the initial frequency minimum point can be calculated using the following formula:

[0117] ;

[0118] In the formula, This indicates the point of lowest initial frequency. Indicates the first parameter. This indicates the maximum permissible frequency deviation of the system.

[0119] C2: Based on the initial lowest frequency point and the frequency approximation curve, calculate and determine multiple first power increment information of multiple frequency modulation resources at the lowest frequency moment.

[0120] This application does not limit the specific method of determining the first power increment information of multiple frequency modulation resources at the lowest frequency moment based on the initial lowest frequency point and the frequency approximation curve. As an example:

[0121] This application can first determine the frequency modulation resources based on the frequency approximation curve and the convolution theorem of the Laplace transform. At the lowest frequency point The power increment is:

[0122] ;

[0123] In the formula, Indicates frequency modulation resources At the lowest frequency point The power increment, Represents the inverse Laplace transform. Let s denote the transfer function, where s is a complex number derived from the Laplace transform. The parameters to be determined are those mentioned above. This represents the step response with respect to the time variable t.

[0124] See If we consider it as a variable, then we have :

[0125]

[0126] In the formula, Indicated by Frequency modulation resources for variables At the lowest frequency point The power increment, when Given a value, it can be obtained directly through discrete integration. , e represents the natural constant, and the other parameters are the same as those described above, and will not be repeated here.

[0127] Understandable, Just to emphasize As variables, and They are equal only because the variables are different. Furthermore, according to... The system frequency at its lowest point needs to meet the following requirements. .

[0128] This application can substitute the initial minimum point as the minimum frequency point into the formula. Frequency modulation resources for variables At the lowest frequency point By obtaining the equation for the power increment, multiple first power increment information can be obtained. Specifically, this can be achieved by first initializing i=1, and then based on the aforementioned power increment... By calculating the formula and taking its discrete integral, the frequency modulation resources can be obtained. power increment Then let i = i + 1, calculate the power increment of the next frequency modulation resource, until it is determined that i is equal to the total number of frequency modulation resources n, and obtain multiple first power increment information.

[0129] C3: Determine the total power increment of the first frequency modulation resource based on multiple pieces of the first power increment information.

[0130] It is understood that this application accumulates multiple first power increment information to determine the total power increment of the first frequency modulation resource. As an example, it can be calculated using the following formula:

[0131] ;

[0132] In the formula, This represents the total power increment of the first frequency modulation resource, where n represents the total number of frequency modulation resources. Indicates frequency modulation resources At the lowest frequency point C4: If the total power increment of the first frequency modulation resource is greater than the power disturbance, then the minimum frequency information of the first system is determined based on the first parameter.

[0133] In this embodiment, after calculating the total power increment of the first frequency modulation resource, the total power increment of the first frequency modulation resource can be compared with the value. If the total power increment of the frequency modulation resource is greater than the power disturbance, then the first parameter can be determined as the required coefficient, and the minimum frequency information of the first system can be determined based on the first parameter.

[0134] This application does not limit the specific method of determining the minimum frequency information of the first system based on the first parameter. As an example, this application determines the minimum frequency value using the following formula for calculating the first system frequency: The formula for calculating the first system frequency is: .

[0135] In the formula, This represents the lowest frequency value, and K represents the first parameter. Indicates the maximum permissible frequency deviation of the system. This indicates the lower limit of the frequency value. This indicates the upper limit of the minimum frequency value. It can be understood that the minimum frequency information for the first system can include the minimum frequency value, the upper limit of the minimum frequency value, and the lower limit of the minimum frequency value.

[0136] C5: Based on the first system's lowest frequency information and the frequency approximation curve, calculate and determine multiple second power increment information of multiple frequency modulation resources at the lowest frequency moment.

[0137] Understandably, after the calculation in step C4, the lowest frequency point in the lowest frequency information of the first system at this point is... This application will substitute the lowest frequency point from the lowest frequency information of the first system into... Frequency modulation resources for variables At the lowest frequency point By obtaining the equation for the power increment, multiple second power increment information can be obtained.

[0138] C6: Determine the total power increment of the second frequency modulation resource based on multiple pieces of the second power increment information.

[0139] This application does not limit the specific method for determining the total power increment of the second frequency modulation resource. As an example, the method for determining the total power increment of the second frequency modulation resource is the same as that for determining the total power increment of the first frequency resource.

[0140] C7: Update the first system minimum frequency information based on the total power increment of the second frequency modulation resource and the power disturbance to obtain the target system minimum frequency information.

[0141] This application does not limit the specific method of updating the first system's minimum frequency information based on the total power increment of the second frequency modulation resources and the power disturbance. As one possible implementation, when the first system's minimum frequency information includes a minimum frequency value, an upper limit of the minimum frequency value, and a lower limit of the minimum frequency value, updating the first system's minimum frequency information based on the total power increment of the second frequency modulation resources and the power disturbance to obtain the target system's minimum frequency information includes steps C71-C72:

[0142] C71: If the total power increment of the second frequency modulation resource is greater than the power disturbance, update the minimum frequency value and the lower limit of the minimum frequency value.

[0143] In this embodiment of the application, after calculating the total power increment of the second frequency modulation resource, it is compared with the power disturbance. If the total power increment of the second frequency modulation resource is greater than the power disturbance, the minimum frequency value and the lower limit of the minimum frequency value are updated.

[0144] This application does not limit the upper limit of the minimum update frequency or the specific method of updating the minimum frequency. As an example, it can be updated sequentially using the following formulas: ;

[0145] In the formula, Indicates the minimum and maximum values ​​of the frequency. Indicates the lowest frequency value. This indicates the lower limit of the frequency value.

[0146] C72: If the first difference between the updated minimum frequency value and the updated minimum frequency value is less than a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

[0147] In this embodiment of the application, after updating the upper limit of the minimum frequency value and the minimum frequency value, the first difference between the upper limit of the minimum frequency value and the minimum frequency value can be calculated, and it can be determined whether the first difference meets the preset threshold. If the first difference is less than the preset threshold, it means that the updated minimum frequency value is the required target system minimum frequency information. After determining the minimum frequency value, the minimum frequency time corresponding to the minimum frequency value can be determined by combining the power increment calculation formula described above.

[0148] Specifically, this application can determine whether the first difference is less than a preset threshold using the following formula:

[0149]

[0150] In the formula, This indicates a preset threshold.

[0151] Updating the minimum frequency value using the above method can provide more accurate information about the system's minimum frequency.

[0152] As one possible implementation, if the first difference is greater than or equal to a preset threshold, the step of calculating and determining the second power increment information of the multiple frequency modulation resources at the lowest frequency based on the first system frequency minimum information and the frequency approximation curve is returned, and steps C5-C7 are executed cyclically until the upper limit of the minimum frequency value and the first difference between the minimum frequency values ​​are determined to be less than the preset threshold.

[0153] As another possible implementation, the minimum frequency information of the first system is updated based on the total power increment and power disturbance of the second frequency modulation resource to obtain the minimum frequency information of the target system, including C73-C74:

[0154] C73: If the total power increment of the second frequency modulation resource is less than or equal to the power disturbance, update the minimum frequency value and the lower limit of the minimum frequency value.

[0155] In this embodiment of the application, after calculating the total power increment of the second frequency modulation resource, it is compared with the power disturbance. If the total power increment of the second frequency modulation resource is less than or equal to the power disturbance, the minimum frequency value and the lower limit of the minimum frequency value are updated.

[0156] This application does not limit the minimum update frequency threshold or the specific method for updating the minimum frequency. As an example, updates can be performed sequentially using the following formulas: ;

[0157] In the formula, Indicates the minimum and maximum values ​​of the frequency. Indicates the lowest frequency value. This indicates the lower limit of the frequency value.

[0158] C74: If the second difference between the updated minimum frequency value and the lower limit of the updated minimum frequency value is less than a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

[0159] In this embodiment of the application, after updating the minimum frequency limit and the minimum frequency value, the second difference between the minimum frequency limit and the minimum frequency value can be calculated, and it can be determined whether the second difference meets the preset threshold. If the second difference is less than the preset threshold, it means that the updated minimum frequency value is the required target system minimum frequency information. After determining the minimum frequency value, the minimum frequency time corresponding to the minimum frequency value can be determined by combining the power increment calculation formula described above.

[0160] Specifically, this application can determine whether the second difference is less than a preset threshold using the following formula:

[0161]

[0162] In the formula, ε represents the preset threshold.

[0163] Updating the minimum frequency value using the above method can provide more accurate information about the system's minimum frequency.

[0164] As one possible implementation, if the second difference is greater than or equal to a preset threshold, the process returns to the step of calculating the second power increment information of multiple frequency-regulating resources at the time of the lowest frequency based on the first system minimum frequency information and the frequency approximation curve, and repeating steps C5-C7 until the upper limit of the minimum frequency value and the second difference between the minimum frequency values ​​are determined to be less than the preset threshold. This method eliminates the need for power system simulation and requires only a small amount of data to calculate the system minimum frequency information, improving the efficiency and convenience of the calculation. Furthermore, in this application, a bisection method is used to find the minimum frequency point and its time within a certain tolerance, requiring only a small number of iterations. In each iteration, the total power increment of the frequency-regulating resources needs to be calculated, which only requires calculating deterministic discrete integrals, resulting in a small computational load. Although this invention approximates the frequency curve, it meticulously considers each link of the frequency control block diagram for each frequency-regulating resource without approximation or simplification. Therefore, it can accurately assess the frequency regulation capability of the frequency-regulating resources and thus accurately calculate the minimum frequency point and its time.

[0165] Furthermore, this application requires minimal data and equipment to evaluate the lowest frequency point and its timing, eliminating the need for additional equipment. The only data required for evaluating the lowest frequency point and its timing are the system inertia M, the initial frequency change rate, and the offline obtained step response of the frequency modulation resources. Complex control diagrams are not necessary for real-time evaluation. The system inertia can be directly obtained from scheduling results or system status, and the initial frequency change rate can be obtained from the PMU device within a few cycles, eliminating the need for additional equipment for data acquisition.

[0166] Furthermore, this application is adaptable to a variety of simple or complex frequency modulation resources. Due to the structured relationship between frequency and power, when calculating the power increment of a frequency modulation resource, the frequency is used as the input. The power increment of the frequency modulation resource can be obtained through experiments, simulations, or calculations. Therefore, as long as the frequency modulation resource does not have a nonlinear element or the nonlinear element is not triggered, its power increment can be calculated quickly and accurately, regardless of how complex or diverse its frequency control model is.

[0167] As one possible implementation, the method for calculating the lowest system frequency information provided in this application further includes:

[0168] If the total power increment of the first frequency regulation resource is less than or equal to the power disturbance, then the first parameter is updated, and the step of determining the initial minimum frequency point of the power system based on the maximum allowable frequency deviation of the system and the first parameter is returned, until the total power increment of the first frequency regulation resource is greater than the power disturbance.

[0169] It is understandable that if it is determined that the total power increment of the first frequency modulation resource is less than or equal to the power disturbance, this application needs to update the first parameter. This application does not limit the specific method of updating the first parameter. As an example, it can be set as follows: Update the first parameter. Then return to step C1, update the initial minimum frequency point using the updated first parameter, and repeat steps C1-C4 until the total power increment of the first frequency modulation resource is greater than the power disturbance. This method can effectively update the first parameter and improve the accuracy of the calculation of the system's minimum frequency information.

[0170] The following is combined Figure 4 To further explain this application, Figure 4 A schematic diagram of the calculation process for the lowest system frequency information provided in this application embodiment includes the following steps:

[0171] (1) Obtaining the system inertia of the power system The first frequency change rate at the moment of power disturbance And calculate the power disturbance. .

[0172] (2) Assume the lowest frequency point is Calculate the sum of frequency modulation resource power increments. The sub-process is as follows:

[0173] a. Initialization .

[0174] b. Using the above Frequency modulation resources for variables At the lowest frequency point By taking the discrete integral of the power increment, the frequency modulation resources can be obtained. power increment .

[0175] c. Judgment Is it equal to the total number of frequency modulation resources n? If so: Calculate Otherwise, let Return to step (2)_b.

[0176] (3) Judgment Is it greater than the power disturbance? ,in the case of:

[0177] make Otherwise, let Return to step (2).

[0178] (4) Calculate the sum of frequency modulation resource power increments. The sub-process is as follows:

[0179] a. Initialization .

[0180] b. Using the above Frequency modulation resources for variables At the lowest frequency point By taking the discrete integral of the power increment, the frequency modulation resources can be obtained. power increment .

[0181] c. Judgment Is it equal to the total number of frequency modulation resources n? If so: Calculate Otherwise, let Return to step (4)_b).

[0182] (5) Judgment Is it greater than the power disturbance? .

[0183] ① If it is: let ,judge Is it true? If true, obtain the result. If not, return to step (4).

[0184] ②If not, let ,judge Is it true? If true, obtain the result. If not, return to step (4).

[0185] The above method eliminates the need for power system simulation and requires only a small amount of data to calculate the minimum system frequency information, thus improving the efficiency and convenience of calculating the minimum system frequency information.

[0186] The following describes a device for calculating the minimum system frequency information provided in an embodiment of this application. The device described below can be referred to in correspondence with the method for calculating the minimum system frequency information described above.

[0187] See Figure 5 , Figure 5 This is a schematic diagram of a computing device for calculating the lowest system frequency information provided in an embodiment of this application. The device includes an acquisition unit 501, a calculation unit 502, and a determination unit 503.

[0188] The acquisition unit 501 is used to acquire the system inertia of the power system, the first frequency change rate at the moment of power disturbance, and the transfer function of the power system.

[0189] The calculation unit 502 is used to calculate the power disturbance of the power system based on the system inertia and the first frequency change rate.

[0190] The determining unit 503 is used to determine the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance amount.

[0191] The calculation unit 502 is further configured to calculate, based on the frequency approximation curve and the power disturbance, using the bisection method to obtain the system minimum frequency information, which includes the minimum frequency value and the time of the minimum frequency.

[0192] As one possible implementation, the determining unit 503 specifically constructs a basic curve of the system frequency deviation of the power system based on the transfer function and the power disturbance.

[0193] Based on the aforementioned basic curve, boundary conditions for the basic curve are introduced;

[0194] The undetermined parameters in the basic curve are solved by the boundary conditions to determine the approximate frequency curve.

[0195] As one possible implementation, the acquisition unit 501 is also used to acquire the step response of the frequency modulation resource;

[0196] The determining unit 503 is further configured to determine the static gain of the frequency modulation resource based on the step response;

[0197] Based on the static gain, the quasi-steady-state frequency of the power system is determined;

[0198] The determining unit 503 is specifically used to: introduce boundary conditions for the basic curve based on the basic curve and the quasi-steady-state frequency.

[0199] As one possible implementation, the acquisition unit 501 is further configured to acquire the maximum permissible frequency deviation of the system and a first parameter, wherein the first parameter is a coefficient used to calculate the initial minimum frequency point of the power system;

[0200] The calculation unit 502 is specifically used for:

[0201] Based on the maximum permissible frequency deviation of the system and the first parameter, the initial minimum frequency point of the power system is determined;

[0202] Based on the initial lowest frequency point and the frequency approximation curve, calculations are performed to determine multiple first power increment information of multiple frequency modulation resources at the lowest frequency moment;

[0203] Based on multiple pieces of the first power increment information, the total power increment of the first frequency modulation resource is determined;

[0204] If the total power increment of the first frequency modulation resource is greater than the power disturbance, then the minimum frequency information of the first system is determined based on the first parameter;

[0205] Based on the first system's lowest frequency information and the frequency approximation curve, calculations are performed to determine multiple second power increment information for multiple frequency modulation resources at the lowest frequency time;

[0206] Based on multiple pieces of the second power increment information, determine the total power increment of the second frequency modulation resource;

[0207] The minimum frequency information of the first system is updated based on the total power increment of the second frequency modulation resource and the power disturbance, thereby obtaining the minimum frequency information of the target system.

[0208] As one possible implementation: the device further includes: an update unit;

[0209] The updating unit is used to update the first parameter if the total power increment of the first frequency regulation resource is less than or equal to the power disturbance amount, and return to the step of determining the initial frequency minimum point of the power system based on the maximum allowable frequency deviation of the system and the first parameter, until the total power increment of the first frequency regulation resource is greater than the power disturbance amount.

[0210] As one possible implementation, the first system minimum frequency information includes the minimum frequency value, the upper limit of the minimum frequency value, and the lower limit of the minimum frequency value.

[0211] The determining unit 503 is specifically used for:

[0212] If the total power increment of the second frequency modulation resource is greater than the power disturbance, update the upper limit of the minimum frequency value and the minimum frequency value;

[0213] If the first difference between the updated minimum frequency value and the updated minimum frequency value is less than a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

[0214] As one possible implementation, the first system minimum frequency information includes the minimum frequency value, the upper limit of the minimum frequency value, and the lower limit of the minimum frequency value.

[0215] The determining unit 503 is specifically used for:

[0216] If the total power increment of the second frequency modulation resource is less than the power disturbance, update the minimum frequency value and the lower limit of the minimum frequency value;

[0217] If the second difference between the updated minimum frequency value and the lower limit of the updated minimum frequency value is less than a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

[0218] It should be noted that the system frequency minimum information calculation device provided in this application embodiment has the technical effects of any of the above embodiments, and will not be described in detail here.

[0219] This application also provides a device for calculating system minimum frequency information, which may include a memory and a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for calculating system minimum frequency information as described in the above embodiments.

[0220] It should be noted that the computing device for system frequency minimum information provided in this application embodiment has the technical effects of any of the above embodiments, and will not be described in detail here.

[0221] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed, can perform the steps provided in the above embodiments. The storage medium may include various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0222] It should be noted that the computer-readable storage medium provided in this application has the technical effects of any of the above embodiments, and the embodiments of this application will not be described in detail here.

[0223] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0224] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0225] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for calculating the lowest system frequency information, characterized in that, include: Obtain the system inertia of the power system, the first rate of change of frequency at the moment of power disturbance, and the transfer function of the power system; The power disturbance of the power system is calculated based on the system inertia and the first frequency change rate. Based on the transfer function and the power disturbance, determine the approximate frequency curve of the system frequency deviation of the power system; Obtain the maximum permissible frequency deviation of the system and a first parameter, wherein the first parameter is a coefficient used to calculate the initial minimum frequency point of the power system; According to the bisection method, the target system's minimum frequency information is obtained by calculating based on the frequency approximation curve and the power disturbance amount. The target system's minimum frequency information includes the minimum frequency value and the time of the minimum frequency. According to the bisection method, the target system minimum frequency information is obtained by calculation based on the frequency approximation curve and the power disturbance, including: determining the initial minimum frequency point of the power system based on the maximum allowable frequency deviation of the system and the first parameter; calculating and determining multiple first power increment information of multiple frequency regulation resources at the minimum frequency time based on the initial minimum frequency point and the frequency approximation curve; determining the total power increment of the first frequency regulation resources based on the multiple first power increment information; if the total power increment of the first frequency regulation resources is greater than the power disturbance, then determining the first system minimum frequency information based on the first parameter; calculating and determining multiple second power increment information of multiple frequency regulation resources at the minimum frequency time based on the first system minimum frequency information and the frequency approximation curve; determining the total power increment of the second frequency regulation resources based on the multiple second power increment information; updating the first system minimum frequency information based on the total power increment of the second frequency regulation resources and the power disturbance to obtain the target system minimum frequency information.

2. The method according to claim 1, characterized in that, Based on the transfer function and the power disturbance, determine the approximate frequency curve of the system frequency deviation of the power system, including: Based on the transfer function and the power disturbance, a basic curve of the system frequency deviation of the power system is constructed. Based on the aforementioned basic curve, boundary conditions for the basic curve are introduced; The undetermined parameters in the basic curve are solved by the boundary conditions to determine the approximate frequency curve.

3. The method according to claim 2, characterized in that, The method further includes: Obtain the step response of the frequency modulation resource; Based on the step response, determine the static gain of the frequency modulation resource; Based on the static gain, the quasi-steady-state frequency of the power system is determined; The boundary conditions introduced based on the base curve include: Based on the fundamental curve and the quasi-steady-state frequency, boundary conditions for the fundamental curve are introduced.

4. The method according to claim 1, characterized in that, The method further includes: if the total power increment of the first frequency regulation resource is less than or equal to the power disturbance, then updating the first parameter and returning to the step of determining the initial minimum frequency point of the power system based on the maximum allowable frequency deviation of the system and the first parameter, until the total power increment of the first frequency regulation resource is greater than the power disturbance.

5. The method according to claim 1, characterized in that, The first system minimum frequency information includes the minimum frequency value, the upper limit of the minimum frequency value, and the lower limit of the minimum frequency value; The first system minimum frequency information is updated based on the total power increment of the second frequency modulation resource and the power disturbance to obtain the target system minimum frequency information, including: If the total power increment of the second frequency modulation resource is greater than the power disturbance, update the upper limit of the minimum frequency value and the minimum frequency value; If the first difference between the updated minimum frequency value and the updated minimum frequency value is less than a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

6. The method according to claim 1, characterized in that, The first system minimum frequency information includes the minimum frequency value, the upper limit of the minimum frequency value, and the lower limit of the minimum frequency value; The first system minimum frequency information is updated based on the total power increment of the second frequency modulation resource and the power disturbance to obtain the target system minimum frequency information, including: If the total power increment of the second frequency modulation resource is less than or equal to the power disturbance, update the minimum frequency value and the lower limit of the minimum frequency value. If the second difference between the updated minimum frequency value and the lower limit of the updated minimum frequency value is less than a preset threshold, the updated minimum frequency value is determined to be the minimum frequency information of the target system.

7. A computing device for system minimum frequency information, characterized in that, include: The acquisition unit is used to acquire the system inertia of the power system, the first frequency change rate at the moment of power disturbance, and the transfer function of the power system. The calculation unit is used to calculate the power disturbance of the power system based on the system inertia and the first frequency change rate. The determining unit is used to determine the approximate frequency curve of the system frequency deviation of the power system based on the transfer function and the power disturbance. The calculation unit is also used to calculate, based on the frequency approximation curve and the power disturbance, according to the bisection method, to obtain the target system minimum frequency information, which includes the minimum frequency value and the time of the minimum frequency. The acquisition unit is further configured to acquire the maximum permissible frequency deviation of the system and a first parameter, wherein the first parameter is a coefficient used to calculate the initial minimum frequency point of the power system; The computing unit is specifically used for: Based on the maximum permissible frequency deviation of the system and the first parameter, the initial minimum frequency point of the power system is determined; Based on the initial lowest frequency point and the frequency approximation curve, calculations are performed to determine multiple first power increment information of multiple frequency modulation resources at the lowest frequency moment; Based on multiple pieces of the first power increment information, the total power increment of the first frequency modulation resource is determined; If the total power increment of the first frequency modulation resource is greater than the power disturbance, then the minimum frequency information of the first system is determined based on the first parameter; Based on the first system's lowest frequency information and the frequency approximation curve, calculations are performed to determine multiple second power increment information for multiple frequency modulation resources at the lowest frequency time; Based on multiple pieces of the second power increment information, determine the total power increment of the second frequency modulation resource; The minimum frequency information of the first system is updated based on the total power increment of the second frequency modulation resource and the power disturbance, thereby obtaining the minimum frequency information of the target system.

8. A computing device for system frequency minimum information, characterized in that, include: Memory, used to store computer programs; A processor for executing a computer program stored in the memory to implement the steps of the method for calculating the lowest system frequency information as claimed in any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program thereon, characterized in that, The computer program is executed by a processor to implement the steps of the method for calculating the lowest system frequency information as described in any one of claims 1 to 6.

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