Method and system for evaluating error of abnormal current transformer on line

Abstract

The invention discloses an abnormal current transformer error online evaluation method and system, and relates to the technical field of power transmission and distribution equipment state evaluation and online monitoring, and the method comprises the steps: calculating a current transformer standard error; drawing a standard error coefficient curve; calculating the actual error of the current transformer; when the actual error current is not equal to the standard error current under the same condition, calculating an error current correlation coefficient variable quantity under the current condition, and when the error current correlation coefficient variable quantity exceeds a threshold value set by the standard error coefficient curve, judging that the current transformer fluctuates; and when the current transformer is judged to have fluctuation, calculating the sum of the three-phase current of the current transformer, and when the sum of the three-phase current exceeds the threshold value of the sum of the three-phase current under the same condition, judging that the transformer is an abnormal transformer. According to the method, the problems that an existing operation current transformer error evaluation method is prone to being affected by the environment and poor in engineering adaptability are solved, and abnormity monitoring and warning of the current transformer are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of state evaluation and online monitoring of power transmission and distribution equipment, and in particular to a method and system for online evaluation of abnormal current transformer errors. Background Art

[0002] In the power system, the current transformer is a vital device. It can measure the current on the transmission line, ensure the accuracy of relay protection and electricity metering, and provide the necessary primary current information for the power system. However, for a long time, the abnormal state of the operating current transformer has always been difficult to be accurately and timely monitored. This situation will not only bring considerable economic losses to the power supply company, increase the power supply cost, increase the burden on other users, but also have an adverse impact on fair and orderly power use. However, due to the inherent characteristics of the current transformer, the physical relationship within its group is relatively complex, and the physical constraints are hidden. It is impossible to achieve online monitoring of the abnormal state of the current transformer by simple mutual comparison. At the same time, the line current changes in the substation are independent of each other, and the current amplitude changes randomly within the range of 0% to 120% of the rated current. The data characteristics of the line current are affected by factors such as system adjustment mode, regional environmental characteristics, load type, and transformer voltage level. The operating status information characteristics are relatively hidden, so it is difficult to achieve online monitoring of the abnormal state of the current transformer.

[0003] At present, the methods for online monitoring of current transformers are mainly divided into two categories, namely, precise modeling method and signal processing method. The idea of ​​precise modeling method is to use the method of model analysis to abstract the physical model of the transformer into a mathematical model containing multiple parameters, obtain the precise values ​​of each parameter by consulting materials or historical operation data, and obtain the transformer operation status information by solving equations. This type of method has poor engineering adaptability, the parameter accuracy obtained in actual engineering is low, and it is easily affected by the environment, so it is often seen in laboratory simulation verification. The signal processing method uses the signal processing method to transform, separate and extract the high-frequency sampling instantaneous value of the output signal of a single transformer, and find the signal component that characterizes the abnormal operation state of the transformer. The error state of the transformer is evaluated by judging the existence and size of the signal component. However, it is not sensitive to the gradual change of the error in long-term operation, and cannot detect the error gradient. It has low recognition accuracy and weak engineering applicability. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to solve the problems of low parameter accuracy, poor engineering adaptability and susceptibility to environmental influences in the existing operating current transformer error evaluation method.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for online evaluation of abnormal current transformer error, which comprises the following steps:

[0007] Based on the loop current balance principle and considering the transformer error, the standard error of the current transformer is calculated;

[0008] According to the standard error coefficient, draw the standard error coefficient curve;

[0009] According to the loop current balance principle, taking into account the transformer error, the actual error of the current transformer is calculated;

[0010] When the actual error current is not equal to the standard error current under the same conditions, the change in the error current correlation coefficient under the current conditions is calculated, and when the change in the error current correlation coefficient exceeds the threshold set by the standard error coefficient curve, it is determined that the current transformer has fluctuations;

[0011] When it is determined that the current transformer has fluctuations, the three-phase current sum of the current transformer is calculated. When the three-phase current sum exceeds the threshold of the three-phase current sum under the same conditions, the transformer is determined to be an abnormal transformer.

[0012] As a preferred solution of the method for online evaluation of abnormal current transformer error described in the present invention, wherein: the calculation of the current transformer standard error includes:

[0013] According to the loop current balance principle, when the transformer error is not considered, the incoming current is equal to the outgoing current, and the expression is:

[0014]

[0015] in, Indicates the incoming current value, n indicates the number of incoming current branches, represents the outgoing current value, m represents the number of outgoing current branches, and j represents the number of transformers.

[0016] As a preferred solution of the method for online evaluation of abnormal current transformer error described in the present invention, wherein: the calculation of the current transformer standard error also includes:

[0017] According to the loop current balance principle, when the transformer error is considered, the expression is:

[0018]

[0019] in, is the standard measured value of the incoming line j branch current, The error standard vector of the transformer of the incoming line j branch, is the standard measured value of the branch current of outgoing line j, The error standard vector of the transformer of the outgoing branch j is: is the standard deviation of the incoming and outgoing line current vector.

[0020] As a preferred solution of the method for online evaluation of abnormal current transformer error described in the present invention, wherein: drawing a standard error coefficient curve according to the standard error coefficient includes:

[0021] According to the standard error coefficient, the error coefficient curve is drawn to express the relationship between the standard error coefficient vector and the standard measurement value of the inlet and outlet currents. The expression is:

[0022]

[0023] in, is the standard error coefficient vector, It is the standard measurement value of the incoming and outgoing line current;

[0024] According to the standard error coefficient of the current transformer of the current node at each percentage current of 1% to 120% under different operating conditions A standard error coefficient curve is drawn as a benchmark for distinguishing current transformer fluctuations and anomalies under this operating condition.

[0025] As a preferred solution of the method for online evaluation of abnormal current transformer error described in the present invention, wherein: the actual error of the current transformer is calculated based on the loop current balance principle and taking the transformer error into consideration, including:

[0026] According to the loop current balance principle, when the transformer error is considered, the expression is:

[0027]

[0028] in, is the actual measured value of the incoming branch current, The actual error vector of the transformer of the incoming line j branch, is the actual measured value of the branch current of outgoing line j, The actual error vector of the transformer in the outgoing branch j is, is the actual difference between the incoming and outgoing line current vectors.

[0029] As a preferred solution of the method for online evaluation of abnormal current transformer error described in the present invention, when the actual error current is not equal to the standard error current under the same conditions, calculating the change in the error current correlation coefficient under the current conditions includes:

[0030] When the error current is not equal to the standard error current under the same conditions, the expression is:

[0031]

[0032] in, is the error current variation;

[0033] Calculate the change in the error current correlation coefficient under the current conditions. The expression is:

[0034]

[0035] in, is the change of the error current correlation coefficient; is the actual measured value of the inlet and outlet current;

[0036] When the error current correlation coefficient changes Exceeds the threshold set by the standard error coefficient curve When , it is judged that the corresponding current transformer has fluctuation;

[0037] On the basis of judging that the current transformer has fluctuation, the three-phase current and the current transformer with fluctuation under the same conditions are compared, and the standard measurement value of each current transformer is obtained after running for a set time period. and the actual measured value Iterative calculation obtains the three-phase current and standard measurement values ​​at each percentage current in the initial operating state When the error between the actual measured value M' and the measured value M' under the same conditions exceeds the threshold When , it is judged that the current transformer is abnormal.

[0038] As a preferred solution of the method for online evaluation of abnormal current transformer error described in the present invention, wherein: the calculation of the three-phase current sum of the current transformer includes:

[0039] The three-phase current signals of the primary side nodes of the power grid satisfy the following relationship:

[0040]

[0041] in, Represents phase A of the three-phase current signal, Represents the B phase of the three-phase current signal, Represents the C phase of the three-phase current signal; Represents the unbalanced current of the node three-phase current signal;

[0042] For current transformer three-phase and current standard measurement values The expression is:

[0043]

[0044] in, and Respectively represent the standard measured values ​​of the A-phase, B-phase and C-phase currents on the n-th branch; Indicates the standard measurement values ​​of three phases and current on the nth branch;

[0045] For the three phases of the current transformer and the actual measured current value M', the relationship is:

[0046]

[0047] in, and Respectively represent the actual measured values ​​of the A-phase, B-phase and C-phase currents on the n-th branch; Indicates the actual measured values ​​of the three-phase and current on the nth branch.

[0048] Under normal conditions, the three-phase imbalance of the power grid fluctuates slightly within a certain period of time and has a statistical change pattern. When the three-phase current and change at a certain moment are different from the change pattern, it indicates that the metering performance is abnormal.

[0049] Another object of the present invention is to provide an online abnormal current transformer error evaluation device, which can solve the problem that the abnormal state of the current transformer is difficult to monitor accurately and timely in the existing technology through several current transformer branches, monitoring devices, remote hosts and clock devices, thereby improving the operation safety and economic efficiency of the power system.

[0050] To solve the above technical problems, the present invention provides the following technical solutions: an online abnormal current transformer error evaluation system, comprising: a plurality of current transformer incoming branches, a plurality of current transformer outgoing branches, a plurality of monitoring devices, a remote host and a clock device;

[0051] The monitoring device comprises a current sampling unit and a data analysis unit connected to each other;

[0052] The current transformer incoming branch and the corresponding current transformer outgoing branch are connected to a current sampling unit of the same monitoring device;

[0053] The current sampling unit includes a signal conditioning unit and a signal sampling unit, which processes and adjusts the original signal obtained from the current transformer, converts the adjusted analog signal into a digital signal, and transmits it to the data analysis unit;

[0054] The data analysis unit includes a communication unit, an operation control unit and a synchronization unit connected in sequence, and the communication unit exchanges and communicates data with the remote host so that data transmission and reception can proceed smoothly;

[0055] The operation control unit receives the digital signal and processes and analyzes it to determine the abnormal current transformer;

[0056] The synchronization unit is linked to the clock device to coordinate the operation and timing relationship between the various components inside the data analysis unit to ensure the stable operation of the data analysis unit.

[0057] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the above-mentioned method for online evaluation of abnormal current transformer errors are implemented.

[0058] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for online evaluation of abnormal current transformer errors.

[0059] Beneficial effects of the present invention: The method for online evaluation of abnormal current transformer errors proposed by the present invention can achieve the purpose of adjusting the air gap length by detachably installing multiple core modules, so as to remove some core modules as needed, so as to ensure that the magnetic flux density in the core is always unsaturated. In addition, since the magnetic flux density of the core is controlled, the method can effectively reduce the core loss at high current. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0061] Figure 1 An overall flow chart of a method for online evaluation of abnormal current transformer error provided by the first embodiment of the present invention;

[0062] Figure 2 A device structure diagram of a device for online evaluation of abnormal current transformer errors provided by a second embodiment of the present invention;

[0063] Figure 3 A comparison diagram between the method of the present invention and a traditional method in an online abnormal current transformer error evaluation method provided by the third embodiment of the present invention. DETAILED DESCRIPTION

[0064] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0065] Example 1, reference Figure 1 According to an embodiment of the present invention, a method for online evaluation of abnormal current transformer error is provided, comprising:

[0066] Reference Figure 1 , which is an embodiment of the present invention, provides a method for online evaluation of abnormal current transformer errors. In order to verify the beneficial effects of the present invention, an experimental platform is built in the laboratory to simulate a two-input and one-output line. Taking 9 0.2S-level current transformers installed on the two-input and one-output line as an example, it is assumed that transformers 2, 3, 4, 7, and 8 have abnormalities, and scientific demonstration is carried out through simulation experiments. The online monitoring data of the current transformer is shown in Table 1:

[0067] Table 1 Current transformer data

[0068]

[0069] S1: Calculate the current transformer standard error.

[0070] When the transformer error is not considered, the incoming current is equal to the outgoing current, which can be expressed as:

[0071]

[0072] in, Indicates the incoming current value, n indicates the number of incoming current branches, represents the outgoing current value, m represents the number of outgoing current branches, and j represents the number of transformers.

[0073] When the current in a branch changes, the error coefficient under the current percentage can also be obtained. The measured current values ​​of the current transformers in each branch of the node are obtained by running for a period of time. The error coefficient k and error current ε of the current transformer of the node under each percentage current of 1% to 120% in the initial operating state are obtained by iterative calculation.

[0074] When considering the transformer error, the following relationship holds:

[0075]

[0076] in, is the standard measured value of the incoming line j branch current, The error standard vector of the transformer of the incoming line j branch, is the standard measured value of the branch current of outgoing line j, The error standard vector of the transformer of the outgoing branch j is: is the standard deviation of the incoming and outgoing line current vector.

[0077] Calculate the standard error of the current transformer As shown in Table 2:

[0078] Table 2 Current transformer standard error

[0079]

[0080] S2: Plot the actual current transformer error.

[0081] According to the standard error coefficient, the error coefficient curve is drawn, and the following relationship exists:

[0082]

[0083] in, is the standard error coefficient vector, It is the standard measurement value of the incoming and outgoing line current.

[0084] According to the standard error coefficient of the current transformer of the node at each percentage current of 1% to 120% under different operating conditions Draw a standard error coefficient curve as a benchmark for judging current transformer fluctuations and anomalies under this operating condition. At the same time, set the threshold value of the standard error coefficient curve

[0085] S3: Calculate the actual error of the current transformer.

[0086] When considering the transformer error, the following relationship holds:

[0087]

[0088] in, is the actual measured value of the incoming branch current, The actual error vector of the transformer of the incoming line j branch, is the actual measured value of the branch current of outgoing line j, The actual error vector of the transformer in the outgoing branch j is, is the actual difference between the incoming and outgoing line current vectors.

[0089] Get the actual error of the current transformer As shown in Table 3.

[0090] Table 3 Actual error of current transformer

[0091]

[0092]

[0093] S4: Current transformer fluctuation determination.

[0094] The current transformer fluctuation determination includes: when the error current is not equal to the standard error current under the same conditions,

[0095]

[0096] in, is the error current variation.

[0097] Calculate the change in the error current correlation coefficient under this condition, the formula is as follows:

[0098]

[0099] in, is the change of the error current correlation coefficient; It is the actual measured value of the incoming and outgoing line current.

[0100] When the actual error current e x When it is not equal to the standard error current e0 under the same percentage conditions of the incoming and outgoing line currents, it must be that the error of a current transformer has changed, and a prediction should be made.

[0101] (1) Assumption Error change, calculate the change in the error current correlation coefficient under this condition If it exceeds the threshold, it is predicted that there is a fluctuation; ...

[0103] (n) Assumption Error change, calculate the change in the error current correlation coefficient under this condition If it exceeds the threshold, it is predicted that there is a fluctuation; ...

[0105] (n+m) Assumption When the error changes, calculate the change in the error current correlation coefficient under this condition If it exceeds the threshold, it is predicted that there is fluctuation.

[0106] When the error current correlation coefficient changes Exceeds the threshold set by the standard error coefficient curve When , it is determined that the corresponding current transformer has fluctuation.

[0107] It should be noted that the error current change that exceeds the threshold value It can only be judged that there is fluctuation in the current transformer, but it cannot be determined that there is an abnormality in the current transformer. There are other possible interference factors such as unbalanced load in the power system, measurement equipment problems, power supply problems, and changes in system parameters.

[0108] Through the above calculation, the change of the error current correlation coefficient of the current transformer is shown in Table 4:

[0109] Table 4 Error correlation coefficient variation

[0110]

[0111]

[0112] This example sets the threshold for the standard error coefficient curve setting Therefore, by comparison, it can be seen that transformers 1, 6 and 9 are qualified, transformer 5 issues an alarm, and transformers 2, 3, 4, 7 and 8 have fluctuations.

[0113] S5: Current transformer abnormality judgment.

[0114] On the basis of judging that the current transformer has fluctuation, it is necessary to further compare the three-phase current and of the current transformer with fluctuation under the same conditions. After running for a certain period of time, the standard measurement value of each current transformer is obtained. and the actual measured value Iterative calculation obtains the three-phase current and standard measurement values ​​at each percentage current in the initial operating state When the error between the actual measured value M' and the measured value M' under the same conditions exceeds the threshold When

[0115]

[0116] It is judged that the current transformer is abnormal.

[0117] The calculation method of the three-phase current sum includes that the three-phase current signals of the primary side nodes of the power grid satisfy the following relationship:

[0118]

[0119] in, Represents phase A of the three-phase current signal, Represents the B phase of the three-phase current signal, Represents the C phase of the three-phase current signal; Represents the unbalanced current of the node's three-phase current signal.

[0120] For current transformer three-phase and current standard measurement values There are the following relationships:

[0121]

[0122] in, and Respectively represent the standard measurement values ​​of the A-phase, B-phase and C-phase currents on the n-th branch; Represents the standard measured values ​​of three-phase and current on the nth branch.

[0123] Calculate the three-phase and current standard measurement values As shown in Table 5.

[0124] Table 5 Three-phase and current standard measurement values

[0125]

[0126] For the three phases of the current transformer and the actual current measurement value M', there is the following relationship:

[0127]

[0128] in, and Respectively represent the actual measured values ​​of the A-phase, B-phase and C-phase currents on the n-th branch; Indicates the actual measured values ​​of the three-phase and current on the nth branch.

[0129] Calculate the actual measured values ​​of three phases and current As shown in Table 6.

[0130] Table 6 Actual measured values ​​of three phases and current

[0131] Transformer 2 3 4 7 8 The actual measured value of the three-phase current and M'(A) 298 300 299 297 296

[0132] Under normal conditions, the three-phase imbalance of the power grid fluctuates very little within a certain period of time and has a statistical change pattern. When the sum of the three-phase currents at a certain moment is different from the change pattern, it indicates that the metering performance is abnormal.

[0133] This example sets the threshold By comparison, it can be seen that transformers 2, 4, 7, and 8 are abnormal, which has higher accuracy compared with the abnormal transformers set in this case.

[0134] For the mutual inductor 3, although the method of the present invention does not detect it as an abnormal mutual inductor, the mutual inductor has fluctuations, and the mutual inductor 3 will be continuously monitored online. When it exceeds the set threshold, it is determined that the mutual inductor has an abnormality.

[0135] Example 2, reference Figure 2 According to an embodiment of the present invention, there is provided a device for online evaluation of abnormal current transformer error method, comprising: a plurality of current transformer incoming branch circuits, a plurality of current transformer outgoing branch circuits, a plurality of monitoring devices, a remote host and a clock device;

[0136] The monitoring device comprises a current sampling unit and a data analysis unit electrically connected to each other;

[0137] The current transformer incoming branch and the corresponding current transformer outgoing branch are connected to a current sampling unit of the same monitoring device;

[0138] The current sampling unit includes a signal conditioning unit and a signal sampling unit, which processes and adjusts the original signal obtained from the current transformer, converts the adjusted analog signal into a digital signal, and transmits it to the data analysis unit;

[0139] The data analysis unit includes a communication unit, an operation control unit and a synchronization unit which are electrically connected in sequence, and the communication unit exchanges and communicates data with the remote host so that data transmission and reception can proceed smoothly;

[0140] The operation control unit receives the digital signal and processes and analyzes it to determine the abnormal current transformer;

[0141] The synchronization unit is linked to the clock device to coordinate the operation and timing relationship between the various components inside the data analysis unit to ensure the stable operation of the data analysis unit.

[0142] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0143] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0144] More specific examples of computer readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer readable medium may be paper or other suitable medium on which the program can be printed, obtained electronically by optically scanning the paper or other medium, then editing, deciphering, or processing in other suitable ways as necessary, and then stored in a computer memory.

[0145] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0146] Example 3, reference Figure 3 As another embodiment of the present invention, in order to verify the effectiveness of the present method, a comparative test was carried out on the same experimental platform and environment, and a conventional current transformer abnormality detection method (loop KCL method) was used for comparison with the present method.

[0147] In the traditional KCL method for detecting abnormal current transformer errors, when the current error exceeds a certain threshold, it is judged to be abnormal. However, this method has great limitations. The actual current transformers have certain errors due to their complex physical structure, but they are not abnormal. Further inspections of individual current transformers are required to determine whether they are abnormal. Taking the 0.2S-level current transformer in this example as an example, the threshold is 0.2A, and the calculation results are shown in Table 3. It can be seen from the table that all current transformers have errors and are abnormal current transformers. Compared with the abnormal transformers assumed in this embodiment, the misjudgment rate is higher.

[0148] like Figure 3 The result analysis of the method of the present invention and the traditional method is demonstrated. By comparison, the accuracy of the abnormality detection result of the current transformer is greatly improved by adopting the method of the present invention, and the time cost of subsequent manual inspection one by one by the traditional method is also greatly reduced.

[0149] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for online evaluation of abnormal current transformer error, characterized in that: include: Based on the loop current balance principle and considering the transformer error, the standard error of the current transformer is calculated; According to the standard error coefficient, draw the standard error coefficient curve; According to the loop current balance principle, taking into account the transformer error, the actual error of the current transformer is calculated; When the actual error current is not equal to the standard error current under the same conditions, the change in the error current correlation coefficient under the current conditions is calculated, and when the change in the error current correlation coefficient exceeds the threshold set by the standard error coefficient curve, it is determined that the current transformer has fluctuations; When it is determined that the current transformer has fluctuations, the three-phase current sum of the current transformer is calculated. When the three-phase current sum exceeds the threshold of the three-phase current sum under the same conditions, the transformer is determined to be an abnormal transformer.

2. The method for online evaluation of abnormal current transformer error according to claim 1, characterized in that: The calculation of the current transformer standard error includes: According to the loop current balance principle, when the transformer error is not considered, the incoming current is equal to the outgoing current, and the expression is: in, Indicates the incoming current value, n indicates the number of incoming current branches, represents the outgoing current value, m represents the number of outgoing current branches, and j represents the number of transformers.

3. The method for online evaluation of abnormal current transformer error according to claim 2, characterized in that: The calculating of the current transformer standard error also includes: According to the loop current balance principle, when the transformer error is considered, the expression is: in, is the standard measured value of the incoming line j branch current, The error standard vector of the transformer of the incoming line j branch, is the standard measured value of the branch current of outgoing line j, The error standard vector of the transformer of the outgoing branch j is: is the standard deviation of the incoming and outgoing line current vector.

4. The method for online evaluation of abnormal current transformer error according to claim 3, characterized in that: Drawing a standard error coefficient curve according to the standard error coefficient includes: According to the standard error coefficient, the error coefficient curve is drawn to express the relationship between the standard error coefficient vector and the standard measurement value of the inlet and outlet currents. The expression is: in, is the standard error coefficient vector, It is the standard measurement value of the incoming and outgoing line current; According to the standard error coefficient of the current transformer of the current node at each percentage current of 1% to 120% under different operating conditions A standard error coefficient curve is drawn as a benchmark for distinguishing current transformer fluctuations and anomalies under this operating condition.

5. The method for online evaluation of abnormal current transformer error according to claim 4, characterized in that: The actual error of the current transformer is calculated based on the loop current balance principle and taking the transformer error into consideration, including: According to the loop current balance principle, when the transformer error is considered, the expression is: in, is the actual measured value of the incoming branch current, The actual error vector of the transformer of the incoming line j branch, is the actual measured value of the branch current of outgoing line j, The actual error vector of the transformer in the outgoing branch j is, is the actual difference between the incoming and outgoing line current vectors.

6. The method for online evaluation of abnormal current transformer error according to claim 5, characterized in that: When the actual error current is not equal to the standard error current under the same conditions, calculating the change in the error current correlation coefficient under the current conditions includes: When the error current is not equal to the standard error current under the same conditions, the expression is: in, is the error current variation; Calculate the change in the error current correlation coefficient under the current conditions. The expression is: in, is the change of the error current correlation coefficient; is the actual measured value of the inlet and outlet current; When the error current correlation coefficient changes Exceeds the threshold set by the standard error coefficient curve When , it is judged that the corresponding current transformer has fluctuation; On the basis of judging that the current transformer has fluctuation, the three-phase current and the current transformer with fluctuation under the same conditions are compared, and the standard measurement value of each current transformer is obtained after running for a set time period. and the actual measured value Iterative calculation obtains the three-phase current and standard measurement values ​​at each percentage current in the initial operating state When the error between the actual measured value M' and the measured value M' under the same conditions exceeds the threshold When , it is judged that the current transformer is abnormal.

7. The method for online evaluation of abnormal current transformer error according to claim 6, characterized in that: The calculation of the three-phase current of the current transformer includes: The three-phase current signals of the primary side nodes of the power grid satisfy the following relationship: in, Represents phase A of the three-phase current signal, Represents the B phase of the three-phase current signal, Represents the C phase of the three-phase current signal; Represents the unbalanced current of the node three-phase current signal; For current transformer three-phase and current standard measurement values The expression is: in, and Respectively represent the standard measurement values ​​of the A-phase, B-phase and C-phase currents on the n-th branch; Indicates the standard measurement values ​​of three phases and current on the nth branch; For the three phases of the current transformer and the actual measured current value M', the relationship is: in, and Respectively represent the actual measured values ​​of the A-phase, B-phase and C-phase currents on the n-th branch; Indicates the actual measured values ​​of the three-phase and current on the nth branch. Under normal conditions, the three-phase imbalance of the power grid fluctuates slightly within a certain period of time and has a statistical change pattern. When the three-phase current and change at a certain moment are different from the change pattern, it indicates that the metering performance is abnormal.

8. A device using the method for online evaluation of abnormal current transformer error according to any one of claims 1 to 7, characterized in that: It includes a plurality of current transformer incoming branch circuits, a plurality of current transformer outgoing branch circuits, a plurality of monitoring devices, a remote host computer and a clock device; The monitoring device comprises a current sampling unit and a data analysis unit connected to each other; The current transformer incoming branch and the corresponding current transformer outgoing branch are connected to a current sampling unit of the same monitoring device; The current sampling unit includes a signal conditioning unit and a signal sampling unit, which processes and adjusts the original signal obtained from the current transformer, converts the adjusted analog signal into a digital signal, and transmits it to the data analysis unit; The data analysis unit includes a communication unit, an operation control unit and a synchronization unit connected in sequence, and the communication unit exchanges and communicates data with the remote host so that data transmission and reception can proceed smoothly; The operation control unit receives the digital signal and processes and analyzes it to determine the abnormal current transformer; The synchronization unit is linked to the clock device to coordinate the operation and timing relationship between the various components inside the data analysis unit to ensure the stable operation of the data analysis unit.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a method for online evaluation of abnormal current transformer errors according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for online evaluation of abnormal current transformer error described in any one of claims 1 to 7 are implemented.

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