Relay protection adaptability quantitative evaluation method and device, terminal equipment and medium

Abstract

The application discloses a relay protection adaptability quantitative evaluation method and device, terminal equipment and medium, the method comprises the following steps: according to the relationship between relay protection and power system model, the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element are determined; according to the parameter characteristics, the parameter adaptation boundary corresponding to each performance index of the protection element is calculated as the quantitative evaluation index of the adaptability of the protection element; according to the relationship between the actual parameters of the power element and the quantitative evaluation index, the quantitative evaluation of the adaptability of the protection element is carried out. The application considers the parameter difference in the process of equivalent mathematical model of the protected element to the real physical model, the selectivity, sensitivity, reliability and other protection performance indexes of the protection, determines the model equivalent error and protection performance demand, can accurately evaluate the adaptability of the protection element in the real electrical system, and has universality.

Description

Technical Field

[0001] This application relates to the field of relay protection technology, and in particular to a method, device, terminal equipment and medium for quantitative assessment of the adaptability of relay protection. Background Technology

[0002] Converters are core components for integrating new energy systems into the power grid. Compared to traditional synchronous machines, power electronic equipment, represented by converters, exhibits fault characteristics that are quite different from conventional systems, such as weak feedback, large differences in positive and negative sequence impedances, and controlled angle of attack. Therefore, it is necessary to evaluate the adaptability of traditional protection principles in new power systems.

[0003] Currently, methods for assessing the adaptability of relay protection mainly fall into two categories: The first is the simulation method, which first obtains the fault characteristics of the system through simulation, and then assesses the adaptability of the protection by combining the fault characteristics with protection criteria. Although this method is simple in principle, it lacks theoretical derivation, and there are numerous fault scenarios in actual power grids. Exhaustive simulation would be too labor-intensive, limiting its applicability and generalizability. The second category is the theoretical derivation method, which obtains fault characteristics through theoretical derivation of power system models, and then compares the corresponding operating conditions and protection criteria to assess the adaptability of the protection. However, this type of research mostly focuses on qualitative analysis of specific protection systems, failing to form a universally applicable quantitative assessment system. Furthermore, this method does not consider the impact of differences between the equivalent mathematical models and actual physical parameters of power components on the operating performance of relay protection components in real systems, thus failing to guarantee the accuracy of the assessment results. Summary of the Invention

[0004] The purpose of this application is to provide a method, device, terminal equipment and medium for quantitative assessment of the adaptability of relay protection, so as to solve the problems of limited applicable scenarios, lack of universality, inability to quantitatively assess and inaccurate assessment results in existing relay protection adaptability assessment methods.

[0005] To achieve the above objectives, this application provides a quantitative assessment method for the adaptability of relay protection, comprising:

[0006] Based on the relationship between relay protection and power system models, determine the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element;

[0007] Based on the parameter characteristics, the parameter adaptation boundary corresponding to each performance index of the protection element is calculated, which serves as a quantitative evaluation index for the adaptability of the protection element.

[0008] Based on the relationship between the actual parameters of the power components and the quantitative evaluation indicators, a quantitative assessment of the adaptability of the protection components is conducted.

[0009] Furthermore, preferably, the calculation satisfies the parameter adaptation boundaries corresponding to each performance index of the protection element, including:

[0010] Calculate the parameter adaptation boundaries that satisfy the selectivity, reliability, speed, and sensitivity indices of the protection element.

[0011] Furthermore, preferably, before determining the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element, the method further includes:

[0012] Determining the relationship between relay protection and the power system model includes determining the protection principle, protection criteria, and the performance of protection components in the actual physical model; among which,

[0013] The protection principle is determined based on the equivalent mathematical model;

[0014] The protection criterion is determined based on the parameter characteristics of the components of the equivalent mathematical model;

[0015] The performance of the protection element in the real physical model is determined by the degree of matching between the equivalent mathematical model and the real physical model.

[0016] Furthermore, preferably, the protected element includes a positive sequence mutation direction element, and the equivalent mathematical model includes an RL model.

[0017] This application also provides a relay protection adaptability quantitative assessment device, comprising:

[0018] The parameter characteristic determination unit is used to determine the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element based on the relationship between the relay protection and the power system model.

[0019] The evaluation index determination unit is used to calculate the parameter adaptation boundary corresponding to each performance index of the protection element based on the parameter characteristics, and to use it as a quantitative evaluation index of the adaptability of the protection element.

[0020] The adaptive quantitative assessment unit is used to perform adaptive quantitative assessment of protection components based on the relationship between the actual parameters of the power components and the quantitative assessment indicators.

[0021] Furthermore, preferably, the evaluation index determination unit is also used for:

[0022] Calculate the parameter adaptation boundaries that satisfy the selectivity, reliability, speed, and sensitivity indices of the protection element.

[0023] Furthermore, preferably, the relay protection adaptability quantitative assessment device further includes:

[0024] The analysis unit is used to determine the relationship between relay protection and the power system model, including determining the protection principle, protection criteria, and the performance of protection components in the actual physical model; among which,

[0025] The protection principle is determined based on the equivalent mathematical model;

[0026] The protection criterion is determined based on the parameter characteristics of the components of the equivalent mathematical model;

[0027] The performance of the protection element in the real physical model is determined by the degree of matching between the equivalent mathematical model and the real physical model.

[0028] Furthermore, preferably, the protected element includes a positive sequence mutation direction element, and the equivalent mathematical model includes an RL model.

[0029] This application also provides a terminal device, including:

[0030] One or more processors;

[0031] A memory, coupled to the processor, for storing one or more programs;

[0032] When the one or more programs are executed by the one or more processors, the one or more processors implement the relay protection adaptive quantitative evaluation method as described in any of the preceding claims.

[0033] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the relay protection adaptability quantitative evaluation method as described in any of the preceding claims.

[0034] Compared to existing technologies, the advantages of this application are as follows:

[0035] This application comprehensively considers the parameter differences that arise during the process of equipping the real physical model of the protected element with a mathematical model, as well as protection performance indicators such as selectivity, sensitivity, and reliability. First, based on the protection principle, the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element are determined. Then, combined with the protection principle, the system parameter indicators affecting its protection adaptability are analyzed, and the parameter adaptation boundary corresponding to meeting the performance requirements of the protected element is calculated based on the parameter characteristics of the equivalent mathematical model and the real physical model. The calculated parameter adaptation boundary is used as an indicator for quantitatively evaluating the protection adaptability. Finally, it compares whether the actual element parameters of the power element meet the above parameter adaptation boundary. If they do, the protection is suitable; if not, the protection is not applicable.

[0036] This application transforms the protection adaptability assessment problem into a power component parameter comparison problem, fully considering model equivalence error and protection performance requirements. It can accurately assess the adaptability of protection components in real electrical systems. Furthermore, both the fault characteristics of the system and the setting of protection criteria are closely related to the system parameters, thus this method has universality. Attached Figure Description

[0037] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments 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 from these drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating a quantitative assessment method for the adaptability of relay protection provided in a certain embodiment of this application;

[0039] Figure 2 This is a schematic diagram of a 150MW photovoltaic system built in PSCAD software according to a certain embodiment of this application;

[0040] Figure 3 This is a schematic diagram illustrating the relationship between relay protection and a power grid model provided in a certain embodiment of this application;

[0041] Figure 4 This is a schematic diagram of the orthogonal mutation network of a two-terminal system provided in a certain embodiment of this application;

[0042] Figure 5 This is a schematic diagram of a quantitative assessment method for the adaptability of relay protection provided in a certain embodiment of this application;

[0043] Figure 6 This is a simulation diagram showing the changes of current, voltage, and phase over time in the adaptability evaluation results provided in a certain embodiment of this application;

[0044] Figure 7 This is a schematic diagram of the curves showing the variation of different line lengths with phase angle according to a certain embodiment of this application;

[0045] Figure 8 This is a schematic diagram of the structure of a relay protection adaptability quantitative evaluation device provided in a certain embodiment of this application;

[0046] Figure 9 This is a schematic diagram of the structure of a terminal device provided in a certain embodiment of this application. Detailed Implementation

[0047] 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, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0048] It should be understood that the step numbers used in the text are for ease of description only and are not intended to limit the order in which the steps are performed.

[0049] It should be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0050] The terms “comprising” and “including” indicate the presence of the described feature, whole, step, operation, element and / or component, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0051] The term “and / or” refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes these combinations.

[0052] Please see Figure 1 This application provides a method for quantitatively evaluating the adaptability of relay protection in one embodiment. For example... Figure 1 As shown, the quantitative assessment method for the adaptability of relay protection includes steps S10 to S30. The specific steps are as follows:

[0053] S10. Based on the relationship between relay protection and power system model, determine the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element.

[0054] Specifically, before performing step S10, it is usually necessary to determine the relationship between the relay protection and the power system model, including determining the protection principle, protection criteria, and the performance of the protection elements in the real physical model.

[0055] The protection principle is determined based on the equivalent mathematical model;

[0056] The protection criterion is determined based on the parameter characteristics of the components of the equivalent mathematical model;

[0057] The performance of the protection element in the real physical model is determined by the degree of matching between the equivalent mathematical model and the real physical model.

[0058] S20. Based on the parameter characteristics, calculate the parameter adaptation boundary corresponding to each performance index of the protection element, and use it as a quantitative evaluation index of the adaptability of the protection element.

[0059] In this step, based on the parameter characteristics obtained in step S10, it is necessary to calculate the parameter adaptation boundaries corresponding to the selectivity index, reliability index, speed index, and sensitivity index of the protection element.

[0060] S30. Based on the relationship between the actual parameters of the power components and the quantitative evaluation indicators, perform a quantitative assessment of the adaptability of the protection components.

[0061] In this step, the actual parameters of the power element are compared with the parameter adaptation boundary. If they are within the boundary, the relay protection is applicable; otherwise, the relay protection is not applicable.

[0062] Please see Figure 2 , Figure 2 A structural schematic diagram of a 150MW photovoltaic system built in PSCAD software is provided. In one specific embodiment, for Figure 2 The system shown has elements with positive sequence mutation direction in... Figure 2 The adaptability of the system is quantitatively evaluated. Specifically, this includes the following steps:

[0063] Step 1: First, study the relationship between relay protection and the power system model, such as... Figure 3 As shown. Specifically, studying the relationship between the two can include:

[0064] 1.1) The protection principle is based on a mathematical model that is equivalent to the actual physical model. The construction of the protection criterion depends on the parameter characteristics of the components in the mathematical model.

[0065] 1.2) The performance of the protection element in the real physical model depends on the degree of matching between the equivalent mathematical model and the real physical model.

[0066] The above analysis shows that the operating performance of relay protection components is closely related to system parameters, specifically as follows:

[0067] a) Protect the features of the equivalent mathematical model parameters upon which the criterion depends.

[0068] b) The degree of parameter matching between the mathematical model on which the protection principle is based and the actual physical model.

[0069] For elements with positive sequence mutation direction, the derived model is the RL model, and the protection principle is based on... Figure 4 The fault supplementary network shown has electrical quantities at the protection installation point as shown in equations (1) and (2) when a forward fault and a reverse fault occur on the m side of the bus:

[0070] (1)

[0071] (2)

[0072] in, Z m1 and Z n1 These represent the equivalent positive-sequence impedances of the system. Δ U m1 Δ I m1 For the positive sequence sudden change in voltage and current of the m-end bus. Z l1 For transmission lines (equivalent to) RL (Model) Positive sequence impedance per unit length, L This is the total length of the line.

[0073] Since the phase of the line impedance and the system impedance in a conventional system is approximately 90°, it can be seen from formulas (1) and (2) that when a forward fault occurs at terminal m, the voltage of each fault component lags behind the current phase by 90°; when a reverse fault occurs at terminal m, the voltage of each fault component leads the current phase by 90°. Therefore, the positive and negative direction criteria for the directional elements of each fault component are given by formulas (3) and (4), respectively:

[0074] (3)

[0075] (4)

[0076] Step Two: Based on the protection principle, analyze the system parameter indicators that affect the protection criteria; for elements with positive sequence mutation direction, set the parameter indicators for evaluating the adaptability of protection as follows:

[0077] 2.1) Equivalent system impedance phase of power supply (synchronous machine, converter station, etc.).

[0078] 2.2) Equivalent impedance phase of the transmission line.

[0079] 3) The degree of matching between the RL model and the actual physical model of the transmission line.

[0080] Step 3: Based on the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element, calculate the parameter adaptation boundary corresponding to the performance indicators (selectivity, reliability, speed, sensitivity, etc.) of the protected element.

[0081] For elements with positive sequence mutation direction, the index parameters corresponding to the correct operation of the protection are:

[0082] 3.1) The equivalent system impedance phase range of the power supply (synchronous machine, converter station, etc.) is [0°, 180°].

[0083] 3.2) The equivalent impedance phase range of the transmission line is (0°, 180°).

[0084] 3.3) When a reverse fault occurs on the m side, the phase of the series impedance of the peer system and the Bergeron-based transmission line is at (0°, 180°).

[0085] Step 4: Compare the equivalent positive-sequence back-side impedance, transmission line parameters, and actual parameters of the peer system of the converter station system to see if they meet the above parameter boundaries. If they do, the protection is applicable; otherwise, the protection is not applicable. For grid-connected photovoltaic power plants, since the phase of the equivalent positive-sequence back-side impedance of the photovoltaic system may be less than 0°, i.e., it does not meet the established parameter boundary indicators, the positive-sequence abrupt change direction element installed on the m side is not applicable. The flowchart of this embodiment from step one to step four is as follows: Figure 5 As shown.

[0086] In one specific embodiment, the above process is verified by simulation: First, based on Figure 2 A grid-connected photovoltaic power plant model is provided. The voltage level is 220kV, the photovoltaic capacity is 150MW, the line uses the Bergeron model, the line length is set to 79.47km, and the impedance parameters are: positive sequence impedance per unit length is... r 1 = 0.073 Ω / km l 1 = 1.27 mH / km c 1 = 0.013 μF When the Jinggangshan Power Plant operates in minimum operating mode, the positive sequence system impedance... Z n The value can be approximated as (1.51+j13.42)Ω.

[0087] The three indicators proposed in the adaptability assessment were analyzed and verified. Regarding indicator 1: Figure 6 The simulation results show the current at the common point, the voltage on the output side, and the phase of the equivalent back-side positive sequence impedance of the bus when a positive ABCG fault occurs on the m side. The fault location is 1 km away, and the transition resistance is 5 Ω. The simulation results show that the phase of the equivalent back-side positive sequence impedance is less than 180°, meaning that index 1 is not satisfied.

[0088] For indicators 2 and 3, based on the above line parameters, it can be determined that when a reverse fault occurs on side m, maintaining the line impedance parameters constant, the following parameters can be obtained for different line lengths. Z m Phase angle as Figure 7 As shown. By Figure 7It can be seen that within the line length range of 0-500km, the calculated result of the positive sequence sudden change impedance phase when a reverse fault occurs on the m side is always within the range of equation (4). Therefore, the positive sequence sudden change directional element will not malfunction when there is a fault outside the m side. This indicates that the applicable line length of the directional element under the impedance parameters of this system exceeds 500km. Combined with the actual line length (79.47km) in the simulation model and the system parameters at the other end, the boundary indices of the model adaptation parameters of indices 2 and 3 are satisfied.

[0089] The proposed method was used to quantitatively evaluate the fitness of positive sequence mutation direction elements. Considering the three quantitative evaluation indicators mentioned above, indicator 1 was no longer satisfied, affecting the selectivity of the protective element. Therefore, even if indicators 2 and 3 were satisfied, the positive sequence mutation direction element... Figure 2 The system shown is still not applicable.

[0090] In summary, the relay protection adaptability quantitative evaluation method provided in this application transforms the protection adaptability evaluation problem into a power component parameter comparison problem, fully considering model equivalence error and protection performance requirements. It can accurately evaluate the adaptability of protection components in real electrical systems. Furthermore, both the fault characteristics of the system and the setting of protection criteria are closely related to the system parameters, thus this method has universality.

[0091] Please see Figure 8 In one specific embodiment of this application, a relay protection adaptability quantitative assessment device is also provided, comprising:

[0092] The parameter characteristic determination unit 01 is used to determine the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element based on the relationship between the relay protection and the power system model.

[0093] The evaluation index determination unit 02 is used to calculate the parameter adaptation boundary corresponding to each performance index of the protection element based on the parameter characteristics, and to use it as a quantitative evaluation index of the adaptability of the protection element.

[0094] The adaptive quantitative assessment unit 03 is used to perform adaptive quantitative assessment of the protection element based on the relationship between the actual parameters of the power element and the quantitative assessment index.

[0095] In one embodiment, the evaluation index determination unit 02 is further configured to:

[0096] Calculate the parameter adaptation boundaries that satisfy the selectivity, reliability, speed, and sensitivity indices of the protection element.

[0097] In one embodiment, the relay protection adaptability quantitative assessment device further includes:

[0098] The analysis unit is used to determine the relationship between relay protection and the power system model, including determining the protection principle, protection criteria, and the performance of protection components in the actual physical model; among which,

[0099] The protection principle is determined based on the equivalent mathematical model;

[0100] The protection criterion is determined based on the parameter characteristics of the components of the equivalent mathematical model;

[0101] The performance of the protection element in the real physical model is determined by the degree of matching between the equivalent mathematical model and the real physical model.

[0102] In one embodiment, the protected element includes a positive sequence mutation direction element, and the equivalent mathematical model includes an RL model.

[0103] It is understood that the relay protection adaptability quantitative evaluation device provided in this embodiment is used to perform the relay protection adaptability quantitative evaluation method as described in any of the above embodiments and achieve the same effect, which will not be further elaborated here.

[0104] Please see Figure 9 One embodiment of this application provides a terminal device, including:

[0105] One or more processors;

[0106] A memory, coupled to the processor, for storing one or more programs;

[0107] When the one or more programs are executed by the one or more processors, the one or more processors implement the relay protection adaptive quantitative evaluation method as described above.

[0108] The processor controls the overall operation of the terminal device to complete all or part of the steps of the aforementioned relay protection adaptive quantitative evaluation method. The memory stores various types of data to support the operation of the terminal device. This data may include, for example, instructions for any application or method used to operate on the terminal device, as well as application-related data. The memory can be implemented using any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0109] In an exemplary embodiment, the terminal device may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the relay protection adaptive quantitative evaluation method as described in any of the above embodiments and achieve the same technical effect as the above method.

[0110] In another exemplary embodiment, a computer-readable storage medium including a computer program is also provided. When executed by a processor, the computer program implements the steps of the relay protection adaptive quantitative evaluation method as described in any of the above embodiments. For example, the computer-readable storage medium may be the aforementioned memory including the computer program, which may be executed by a processor of a terminal device to complete the relay protection adaptive quantitative evaluation method as described in any of the above embodiments and achieve the same technical effects as the aforementioned method.

[0111] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A quantitative assessment method for the adaptability of relay protection, characterized in that, include: Based on the relationship between relay protection and power system models, determine the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element; Determining the relationship between relay protection and the power system model includes determining the protection principle, protection criteria, and the performance of protection components in the actual physical model; among which, The protection principle is determined based on the equivalent mathematical model; The protection criterion is determined based on the parameter characteristics of the components of the equivalent mathematical model; The performance of the protection element in the real physical model is determined by the degree of matching between the equivalent mathematical model and the real physical model; Based on the parameter characteristics, the parameter adaptation boundary corresponding to each performance index of the protection element is calculated, which serves as a quantitative evaluation index for the adaptability of the protection element. Based on the relationship between the actual parameters of the power components and the quantitative evaluation indicators, a quantitative assessment of the adaptability of the protection components is conducted.

2. The method for quantitative assessment of relay protection adaptability according to claim 1, characterized in that, The calculation satisfies the parameter adaptation boundaries corresponding to each performance index of the protection element, including: Calculate the parameter adaptation boundaries that satisfy the selectivity, reliability, speed, and sensitivity indices of the protection element.

3. The method for quantitative assessment of relay protection adaptability according to claim 1, characterized in that, The protected element includes a positive sequence mutation direction element, and the equivalent mathematical model includes an RL model.

4. A quantitative assessment device for the adaptability of relay protection, characterized in that, include: The parameter characteristic determination unit is used to determine the parameter characteristics of the equivalent mathematical model and the real physical model of the protected element based on the relationship between the relay protection and the power system model. The analysis unit is used to determine the relationship between relay protection and the power system model, including determining the protection principle, protection criteria, and the performance of protection components in the actual physical model; among which, The protection principle is determined based on the equivalent mathematical model; The protection criterion is determined based on the parameter characteristics of the components of the equivalent mathematical model; The performance of the protection element in the real physical model is determined by the degree of matching between the equivalent mathematical model and the real physical model; The evaluation index determination unit is used to calculate the parameter adaptation boundary corresponding to each performance index of the protection element based on the parameter characteristics, and to use it as a quantitative evaluation index of the adaptability of the protection element. The adaptive quantitative assessment unit is used to perform adaptive quantitative assessment of protection components based on the relationship between the actual parameters of the power components and the quantitative assessment indicators.

5. The relay protection adaptability quantitative evaluation device according to claim 4, characterized in that, The evaluation index determination unit is also used for: Calculate the parameter adaptation boundaries that satisfy the selectivity, reliability, speed, and sensitivity indices of the protection element.

6. The relay protection adaptability quantitative evaluation device according to claim 4, characterized in that, The protected element includes a positive sequence mutation direction element, and the equivalent mathematical model includes an RL model.

7. A terminal device, characterized in that, include: One or more processors; A memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the relay protection adaptive quantitative evaluation method as described in any one of claims 1-3.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the relay protection adaptability quantitative evaluation method as described in any one of claims 1-3.

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