Group high-voltage current transformer operation metering error evaluation method and storage medium

Abstract

The invention discloses a group high-voltage current transformer operation metering error evaluation method and a storage medium. The method comprises the steps of S1, data acquisition; the method comprises the following steps: acquiring known measurable electric power data, and extracting various information physical relationships and massive mutual inductor measurement data sets by analyzing three-phase power electrical physical relationships of a power grid; s2, modeling is carried out; determining a direct constraint relation of the current transformer, establishing a plurality of target sub-functions, and converting an error evaluation problem into a multi-target solving problem; s3, optimization solution is carried out; a multi-target multi-constraint problem is solved, and a CT primary side current truth value set # imgabs0 # is obtained; S4, evaluation is carried out; the mutual inductor error is evaluated according to the optimal solution, the error E of the n CTs of the to-be-detected group is calculated, and E is the final evaluation result. The storage medium is used for storing a computer program for executing the method. The method has the advantages of being simple in principle, good in real-time performance, wide in application range, low in evaluation cost and the like.

Description

Technical Field

[0001] The present invention mainly relates to the field of online monitoring of electric power metering, and in particular to a method for evaluating the operation metering error of a group of high-voltage current transformers and a storage medium. Background Art

[0002] High-voltage current transformers play a vital role in the power system and are an important part of the electric energy metering device, because the accuracy and reliability of their metering performance are directly related to the fairness and justice of electric energy trade settlement. Current transformers can be used to measure current and convert it into a smaller current proportional to the original current for monitoring, control and protection. However, due to various factors, such as manufacturing process, use environment, aging degree, etc., the performance of high-voltage current transformers may change, resulting in measurement errors. Mastering the error state of high-voltage current transformers helps ensure the stability and safety of the power system. Accurate current measurement is the basis for ensuring the normal operation of the power grid. Any error may cause abnormal system operation or even accidents. Therefore, evaluating the error state of high-voltage current transformers can help prevent potential failures. In power trading and energy management, accurate electric energy metering is crucial, and high-voltage current transformer errors may affect the accuracy of electric energy metering, resulting in disputes or losses in energy trading. Therefore, it is of great significance to evaluate the error state of high-voltage current transformers.

[0003] High-voltage current transformers are mainly used in transmission networks, which are lines that require accurate energy measurement. By evaluating the error state of high-voltage current transformers, the accuracy of energy measurement can be improved. At present, the standard calibration method is usually used for the error evaluation of high-voltage current transformers: the power grid is shut down, and the high-voltage current transformer is inspected by using a standard calibration device, and the error state is evaluated by comparing the difference between its output value and the standard value. This method usually requires professional calibration equipment and experimental conditions and has high accuracy. Through this method, the high-voltage current transformer is calibrated regularly, and the difference between its output value and the standard value is compared to evaluate the error state. The frequency and method of calibration can be adjusted according to actual conditions and requirements to ensure the accuracy and reliability of the measurement results. However, this type of method requires the distribution network line to be shut down, which is difficult to operate and has a great impact on the operation of the line network. The online evaluation method does not require power outage and is more suitable for the actual operation of the distribution network. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in response to the technical problems existing in the prior art, the present invention provides a method and storage medium for evaluating the operation metering error of a group high-voltage current transformer, which has a simple principle, good real-time performance, a wide range of applications and low evaluation cost.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for evaluating the operation measurement error of a group high-voltage current transformer, comprising:

[0007] Step S1: data collection: collect known measurable power data, analyze the electrical physical relationship of the three-phase power of the power grid, extract multiple information physical relationships and massive transformer measurement data sets;

[0008] Step S2: Modeling; determining the constraint relationship directly existing in the current transformer, establishing multiple objective sub-functions, and converting the error evaluation problem into a multi-objective solution problem;

[0009] Step S3: Optimization solution: Solve the multi-objective and multi-constraint problem to obtain the CT primary side current true value set

[0010] Step S4: Evaluation: Evaluate the mutual inductor error according to the optimal solution, and calculate the error E of the n CTs in the group to be tested, where E is the final evaluation result.

[0011] As a further improvement of the present invention: in the step S1, real-time power data of multiple transformers are collected to construct sample data.

[0012] As a further improvement of the present invention: the high-voltage current transformers with topological relationship in the three-phase circuits of the power grid to be tested are taken as a group, the number of groups of transformers is n, each group of transformers is divided into three phases ABC, and the group CT power data is collected as the source of online evaluation data for the current transformer error; the three-phase circuit electric energy representation of the n groups of transformers and the three-phase average power P are collected, Px is the average power of the three-phase circuit of the x-th group of transformers, the three-phase reactive power Qx of the x-th group of transformers is collected, the group transformer records the transformation ratio kx of the x-th group of transformers, and the secondary side current I of each transformer is collected. T , I T =i T1 ,i T2 ,...,i Tn .

[0013] As a further improvement of the present invention: in step S2, mathematical modeling is performed on the relevant physical quantities, and the following symbols are defined: is the vector truth value set of the primary current of the group CT to be solved, The angle by which current lags behind voltage is u xA ,u xB ,u xC are the primary side voltages of phases A, B and C of the xth group of transformers respectively;

[0014] Construct the following objective function;

[0015]

[0016] According to the above 6 objective sub-functions, construct the objective function:

[0017]

[0018] As a further improvement of the present invention: in the step S3, the cuckoo search algorithm is used to solve the optimal solution; the data relationship and physical relationship of the CT group in the power grid to be tested are the goals of mathematical solution, st constitutes a constraint condition, and the "power grid power data acquisition value-CT primary side current true value set" is transformed into a multi-constraint and multi-objective optimization problem. The multi-objective and multi-constraint problem is solved by the optimization algorithm to obtain the CT primary side current true value set

[0019] As a further improvement of the present invention: the process of step S3 includes:

[0020] Step S301: setting search boundaries;

[0021] Using the historical current data of the power grid, the primary side true value calculated according to the current power grid measurement value is used as the upper and lower limits of the value, denoted as

[0022] Step S302: Use the cuckoo search algorithm to find the optimal solution and initialize the parameters; use the number of CTs in the group n as the number of bird nests and set the maximum number of iterations MaxIt. Other parameters are selected by default;

[0023] Step S303: Randomly initialize a certain number of bird nests within the boundary range and calculate The objective function value;

[0024] Step S304: Iteration loop; global search, compare the objective function with the optimal solution, if it is superior to the previous solution, replace the optimal value and the optimal solution;

[0025] Step S305: determine whether the loop reaches the maximum number of iterations Max I t, otherwise jump to step S303. As a further improvement of the present invention: in step S4, the mutual inductor error is evaluated according to the optimal solution;

[0026] To find the optimal solution, i.e., the true value set of the primary current of the CT, the error E of the n CTs in the group to be tested is calculated, E = (e1, e2, ..., ei, ... en), the error of the i-th transformer is ei, which is divided into the ratio error of the real part and the angle difference of the imaginary part

[0027]

[0028] (1≤i≤n)

[0029] E is the final evaluation result.

[0030] The present invention further provides a storage medium, which can be read by a computer or a processor, and stores a computer program for executing any one of the above methods.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] 1. The method and storage medium for evaluating the operation metering error of a group of high-voltage current transformers of the present invention have a simple principle, good real-time performance, and a wide range of applications. The method aims to solve the problem that the offline evaluation of the error state of traditional high-voltage current transformers requires power outages, which has a significant impact on the operation of the power grid. The present invention collects known measurable power data, analyzes the electrical and physical relationship of the three-phase power of the power grid, extracts a variety of information-physical relationships and massive transformer measurement data sets, and converts the error evaluation problem into a multi-objective problem. Determine the constraint relationship that directly exists in the current transformer, establish multiple target sub-functions, and optimize and solve them, so that the metering error state of large-scale current transformers under environmental conditions that are difficult to obtain on the primary side of the current value can be evaluated online. The problem that the offline evaluation requires power outages and has a significant impact on the operation of the power grid is solved through online evaluation, and the evaluation cost is reduced.

[0033] 2. The group high-voltage current transformer operation metering error evaluation method and storage medium of the present invention directly evaluates the transformer error by collecting data analysis, is not affected by the environment, has irreplaceable technical advantages, and has great practical value for improving the power supply safety and reliability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the process of the present invention in a specific embodiment.

[0035] Figure 2 It is a schematic diagram of the comparison results between the present invention and the traditional method after specific application. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, the method for evaluating the operation metering error of a group high-voltage current transformer of the present invention comprises:

[0038] Step S1: data collection;

[0039] Collect known and measurable power data, and extract multiple information-physical relationships and massive transformer measurement data sets by analyzing the electrical-physical relationship of the three-phase power of the power grid;

[0040] Step S2: Modeling;

[0041] Determine the constraints directly existing in the current transformer, establish multiple objective subfunctions, and transform the error evaluation problem into a multi-objective solution problem;

[0042] Step S3: Optimization solution;

[0043] Solve the multi-objective and multi-constraint problem and obtain the true value set of the CT primary current

[0044] Step S4: Evaluation: The metering error state of large-scale current transformers is evaluated online, the transformer error is evaluated according to the optimal solution, and the error E of the n CTs in the group to be measured is calculated, where E is the final evaluation result.

[0045] In a specific application example, in step S1, real-time power data of multiple transformers are collected to construct sample data.

[0046] Specifically, the high-voltage current transformers with topological relationship in the three-phase circuit of the power grid to be tested are taken as a group (for example, the transformers are not less than 20 groups), the number of transformer groups is n, and each group of transformers is divided into three phases ABC. The group CT power data is collected as the source of online evaluation data for the current transformer error. The three-phase circuit electric energy representation of the n groups of transformers and the three-phase average power P are collected, where Px is the average power of the three-phase circuit of the x-th group of transformers. The three-phase reactive power Qx of the x-th group of transformers is collected. The group transformer records the transformation ratio kx of the x-th group of transformers, and the secondary current I of each transformer is collected. T , I T =i T1 ,i T2 ,...,i Tn .

[0047] In a specific application example, in step S2, an evaluation model is established; specifically, mathematical modeling is performed on relevant physical quantities, and the following symbols are defined:

[0048] is the vector truth value set of the primary current of the group CT to be solved, The angle by which current lags behind voltage is u xA ,u xB ,u xC They are the primary side voltages of phases A, B, and C of the xth group of transformers respectively.

[0049] Construct the following objective function.

[0050]

[0051] According to the above 6 objective sub-functions, construct the objective function:

[0052]

[0053] In the specific application example, in the step S3, the cuckoo search algorithm is used to solve the optimal solution; the data relationship and physical relationship of the CT group in the power grid to be tested are the goals of mathematical solution, and st constitutes a constraint condition. The present invention transforms the "power grid power data acquisition value-CT primary side current true value set" into a multi-constraint and multi-objective optimization problem, and uses the intelligent optimization algorithm to solve the multi-objective and multi-constraint problem to obtain the CT primary side current true value set.

[0054] It should be noted that the core idea of ​​the cuckoo search algorithm is to find the optimal solution in the search space by simulating the parasitic behavior of cuckoos. The cuckoo search algorithm is based on the following two main operations: Random walk of the cuckoo population: Each cuckoo individual will randomly select a location in the solution space for search. Through this random walk, the cuckoo has the opportunity to explore a wider search space to find better solutions. Information transmission and learning of cuckoos: The parasitic behavior of cuckoos is the key feature of the algorithm. In parasitic behavior, cuckoos will find and replace better solutions. Specifically, better cuckoo individuals will replace worse individuals and pass their information to other cuckoos to promote the learning and evolution of the entire population. The advantages of the cuckoo search algorithm include being simple and easy to implement, not requiring too many parameters to be set, and being able to search globally. It has certain advantages in solving complex optimization problems.

[0055] Specifically, the specific solution process of the present invention may include:

[0056] Step S301: setting search boundaries;

[0057] Using the historical current data of the power grid, the primary side true value calculated according to the current power grid measurement value is used as the upper and lower limits of the value, denoted as

[0058] Step S302: Introduce the modified cuckoo search algorithm to find the optimal solution and initialize the parameters; use the number of CTs in the group n as the number of bird nests and set the maximum number of iterations MaxIt. Other parameters are selected by default;

[0059] Step S303: Randomly initialize a certain number of bird nests within the boundary range and calculate The objective function value;

[0060] Step S304: Iteration loop; global search, compare the objective function with the optimal solution, if it is superior to the previous solution, replace the optimal value and the optimal solution;

[0061] Step S305: Determine whether the loop reaches the maximum number of iterations Max I t, otherwise jump to step S303.

[0062] In a specific application example, in step S4, the mutual inductor error is evaluated according to the optimal solution;

[0063] To find the optimal solution, i.e., the true value set of the primary current of the CT, the error E of the n CTs in the group to be tested is calculated, E = (e1, e2, ..., ei, ... en), the error of the i-th transformer is ei, which is divided into the ratio error of the real part and the angle difference of the imaginary part

[0064]

[0065] (1≤i≤n)

[0066] E is the final evaluation result.

[0067] The present invention has achieved the non-stop evaluation of the measurement error of high-voltage voltage transformer by designing a group high-voltage current transformer error online evaluation method. In a specific application example, the present invention evaluates the error of a group of CTs in a certain power grid area through the method of this patent, the number of CTs is 100, and the ratio difference and angle difference evaluation data are obtained. The regional power grid is shut down, and the above CT ratio difference is evaluated offline according to the traditional method. The evaluation result is used as the true value of the error, and the true value is compared with the error evaluated by the method of the present invention. The result is as follows: Figure 2 As shown in the figure, it can be seen that the evaluation error result of the present invention is close to the true value of the error, which shows that the evaluation accuracy of the present invention is relatively high.

[0068] The present invention further provides a storage medium, which can be read by a computer or a processor and stores a computer program for executing the above method.

[0069] Those skilled in the art will appreciate that the above-mentioned embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0070] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for evaluating the operation measurement error of a group high-voltage current transformer, characterized in that: include: Step S1: data collection: collect known measurable power data, analyze the electrical physical relationship of the three-phase power of the power grid, extract multiple information physical relationships and massive transformer measurement data sets; Step S2: Modeling; Determine the constraints directly existing in the current transformer, establish multiple objective sub-functions, and transform the error evaluation problem into a multi-objective solution problem; Step S3: Optimization solution; Solve the multi-objective and multi-constraint problem and obtain the true value set of the CT primary current Step S4: Evaluation: Evaluate the mutual inductor error according to the optimal solution, and calculate the error E of the n CTs in the group to be tested, where E is the final evaluation result.

2. The method for evaluating the operation measurement error of a group high-voltage current transformer according to claim 1 is characterized in that: In the step S1, real-time power data of multiple transformers are collected to construct sample data.

3. The method for evaluating the operation measurement error of a group high-voltage current transformer according to claim 2 is characterized in that: The high-voltage current transformers with topological relationship in the three-phase circuit of the power grid to be tested are taken as a group, the number of groups of transformers is n, and each group of transformers is divided into three phases ABC. The group CT power data is collected as the data source for online evaluation of current transformer errors; the three-phase circuit electric energy representation of the n groups of transformers and the three-phase average power P are collected, where Px is the average power of the three-phase circuit of the x-th group of transformers, the three-phase reactive power Qx of the x-th group of transformers is collected, the group transformer records the transformation ratio kx of the x-th group of transformers, and the secondary current I of each transformer is collected. T , I T =i T1 ,i T2 ,...,i Tn .

4. The method for evaluating the operation measurement error of a group high-voltage current transformer according to any one of claims 1 to 3, characterized in that: In step S2, mathematical modeling is performed on the relevant physical quantities, and the following symbols are defined: is the vector truth value set of the primary current of the group CT to be solved, The angle by which current lags behind voltage is u xA ,u xB ,u xC are the primary side voltages of phases A, B and C of the xth group of transformers respectively; Construct the following objective function; According to the above 6 objective sub-functions, construct the objective function:

5. The method for evaluating the operation measurement error of a group high-voltage current transformer according to any one of claims 1 to 3, characterized in that: In step S3, the cuckoo search algorithm is used to solve the optimal solution; the data relationship and physical relationship of the CT group in the power grid to be tested are the goals of the mathematical solution, and st constitutes a constraint condition. The "power grid power data acquisition value-CT primary side current true value set" is transformed into a multi-constraint and multi-objective optimization problem. The multi-objective and multi-constraint problem is solved by the optimization algorithm to obtain the CT primary side current true value set.

6. The method for evaluating the operation measurement error of a group high-voltage current transformer according to claim 5, characterized in that: The process of step S3 includes: Step S301: setting search boundaries; Using the historical current data of the power grid, the primary side true value calculated according to the current power grid measurement value is used as the upper and lower limits of the value, denoted as Step S302: Use the cuckoo search algorithm to find the optimal solution and initialize the parameters; use the number of CTs in the group n as the number of bird nests and set the maximum number of iterations MaxIt. Other parameters are selected by default; Step S303: Randomly initialize a certain number of bird nests within the boundary range and calculate The objective function value; Step S304: Iteration loop; global search, compare the objective function with the optimal solution, if it is superior to the previous solution, replace the optimal value and the optimal solution; Step S305: Determine whether the loop reaches the maximum number of iterations MaxIt, otherwise jump to step S303.

7. The method for evaluating the operation measurement error of a group high-voltage current transformer according to any one of claims 1 to 3, characterized in that: In step S4, the mutual inductor error is evaluated according to the optimal solution; I * N To find the optimal solution, i.e., the true value set of the primary current of the CT, the error E of the n CTs in the group to be tested is calculated, E = (e1, e2, ..., ei, ... en), the error of the i-th transformer is ei, which is divided into the ratio error of the real part and the angle difference of the imaginary part (1≤i≤n) E is the final evaluation result.

8. A storage medium, which can be read by a computer or a processor, characterized in that: The storage medium stores a computer program for executing any one of the methods in claims 1 to 7.

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