Cross-range metering current transformer error interval division method and related equipment

Abstract

The embodiment of the invention provides a cross-range metering current transformer error interval division method and corresponding equipment. The method comprises the following steps: S1, arranging a current transformer with a plurality of transformation ratio ranges in an electric energy metering circuit; s2, constructing an error limit value band of the current transformer according to the rated secondary current of the set working range of the current transformer; s3, collecting the change of the secondary current of the current transformer; s4, on the basis of the change of the secondary current of the current transformer and the error limit value band, carrying out transformation ratio range switching through current transformer online switching equipment; the switching process is that when the secondary current of the current transformer is larger than the maximum value of an error limit value band, namely 120% or more of the rated secondary current, the current transformer is switched to a large-load current transformation ratio; when the secondary current of the current transformer is less than 20% of the rated secondary current, namely the minimum value of the error limit band, switching to a small load current transformation ratio; the method has the beneficial effect of improving operation efficiency and stability of a power system and is suitable for the field of electric energy metering.

Description

Technical Field

[0001] The present application relates to the technical field of electric energy metering, and in particular to a method for dividing error intervals of a current transformer for cross-range metering and related equipment. Background Art

[0002] In modern power systems, electric energy measurement is an important task, which involves the normal operation of the power system and the economic interests of power users. Electric energy metering devices mainly include: various types of electric energy meters, voltage / current transformers for measurement and their secondary circuits, electric energy metering cabinets (boxes), etc. Among them: current transformers are important equipment for electric energy measurement, and their function is to convert various primary large currents into specified secondary small currents of 5A or 1A (for special circumstances) to facilitate electric energy meter measurement.

[0003] However, with the development of the power system, the range of load changes is getting wider and wider, which puts higher requirements on electric energy metering equipment, especially medium-voltage current transformers below 35kV; according to the configuration principle of electric energy metering devices in "DL / T448-2016 Technical Management Regulations for Electric Energy Metering Devices": "The determination of the rated primary current of the current transformer should ensure that its actual load current in normal operation reaches about 60% of the rated value, and should be at least not less than 30%", and the actual small load current of the two-way metering of new energy power generation and consumption such as heating and wind power reaches less than 1% of the rated value, resulting in inaccurate electric energy metering. Usually, the lighter the load, the smaller the primary current and the more negative the ratio, that is, more is actually used but less is measured.

[0004] The existing solutions are mainly: using two sets of metering systems with large ratio range and small ratio range to switch according to power outages as needed, or replacing current transformers with different ratio ranges to adapt to different load ranges; when the load current is relatively large, current transformers with larger ratio ranges are generally designed according to regulations to ensure the accuracy of electric energy measurement. This method causes the secondary current to be too small when the load current is relatively small, making it impossible for the electric energy meter to accurately measure the mA-level latent current, and the unmetered electricity can only be shared with the electricity user according to the line loss.

[0005] In addition, when the traditional solution is to interrupt the power supply and change the transformation ratio to solve the problem of energy leakage metering, the operation is complicated and costly because the transformer needs to be replaced manually.

[0006] In summary, when dealing with ultra-large-scale load changes and two-way metering problems, the existing technology cannot guarantee the stability and reliability of electricity metering, and there are shortcomings such as power-off switching problems and the danger of manual online operation; and the existing electricity metering equipment cannot adapt to the power generation and consumption needs of an ultra-wide current load range, and there will be metering inaccuracies such as leakage metering; in addition, the two existing sets of electricity metering equipment increase the manufacturing cost and operation and maintenance management cost of the metering cabinet when dealing with a large range of load changes and two-way metering problems in medium voltage below 35kV. Summary of the invention

[0007] In order to solve one of the above-mentioned technical defects, the embodiments of the present application provide a method for dividing the error interval of a current transformer for cross-range measurement and related equipment, which can improve the operating efficiency and stability of the power system.

[0008] According to a first aspect of an embodiment of the present application, a method for dividing a current transformer error interval for cross-range measurement is provided, comprising:

[0009] S1, a current transformer with multiple ratio ranges is arranged in the metering circuit;

[0010] S2, constructing the error limit band of the current transformer according to the rated secondary current of the set current transformer working range;

[0011] S3, collecting the change of secondary current of current transformer;

[0012] S4, based on the change of the secondary current of the current transformer and the error limit band, the ratio range is switched through the current transformer online switching device;

[0013] The switching process is: when the secondary current of the current transformer is greater than the maximum value of the error limit band, it switches to a large load current ratio; when the secondary current of the current transformer is less than the minimum value of the error limit band, it switches to a small load current ratio.

[0014] Preferably, in a power application scenario with periodic load conversion, the switching process further includes:

[0015] The process of switching from a large load current ratio to a small load current ratio needs to be performed after the load current is reduced;

[0016] The process of switching from a small load current ratio to a large load current ratio needs to be performed before the load current increases.

[0017] Preferably, the error limit band of the current transformer is: 20% to 120% of the rated secondary current of the current transformer working range;

[0018] The maximum value of the error limit band is: 120% of the rated secondary current of the current transformer working range;

[0019] The minimum value of the error limit band is: 20% of the rated secondary current of the current transformer working range.

[0020] Preferably, the structure of the current transformer includes: a primary winding and a secondary winding;

[0021] The primary winding includes: a primary polarity end P1 and a primary non-polarity end P2;

[0022] The secondary winding comprises: a secondary polarity end and a plurality of secondary non-polarity ends to obtain different transformation ratios; the secondary polarity end is matched with any non-polarity end of the secondary winding to form a plurality of transformation ratio ranges respectively.

[0023] Preferably, the structure of the current transformer includes: a primary winding and a secondary winding; the primary winding includes: a first winding, the first winding is composed of a plurality of turns of coils, the starting end of the first turn of the coil is connected to the polarity end P11 of the first winding, the ending end of the last turn of the coil passes through the second winding and is connected to the non-polarity end P22 of the first winding, and the first winding or the second winding shares a primary circuit;

[0024] The secondary winding includes: a secondary polarity end S11 and a plurality of secondary non-polarity ends;

[0025] The secondary polarity end of the first winding is connected in parallel with the secondary polarity end S11 of the second winding;

[0026] The secondary polarity end S11 matches the primary winding with different secondary non-polarity ends to form different transformation ratio ranges.

[0027] Preferably, the current transformer is an S-class current transformer.

[0028] According to a second aspect of an embodiment of the present application, a current transformer error interval division device for cross-range measurement is provided, comprising:

[0029] A cross-range current transformer, which is arranged in an electric energy metering circuit and has multiple ratio ranges;

[0030] A construction unit, used for constructing an error limit band of the current transformer according to the rated current of the set working range of the current transformer;

[0031] A collection unit, used for collecting changes in the secondary current of the current transformer;

[0032] Cross-range current transformer online switching equipment, used to switch the current transformer ratio range based on the change of the current transformer secondary current and the error limit band;

[0033] Among them, the switching process is: when the secondary current of the current transformer is greater than the maximum value of the error limit band (that is, more than 120% of the rated secondary current), switch to a large load current ratio; when the secondary current of the current transformer is less than the minimum value of the error limit band (that is, less than 20% of the rated secondary current), switch to a small load current ratio.

[0034] According to a third aspect of an embodiment of the present application, there is provided an electronic device, including:

[0035] memory; processor; and computer program;

[0036] The computer program is stored in the memory and is configured to be executed by the processor to implement the method as described above.

[0037] According to a fourth aspect of an embodiment of the present application, a computer-readable storage medium is provided, on which a computer program is stored; the computer program is executed by a processor to implement the method as described above.

[0038] The embodiment of the present application adopts the above technical solution, which has the following technical effects:

[0039] 1. In this application, the current transformer online switching device can switch the ratio range under different working conditions. When dealing with large-scale load changes and bidirectional metering problems in medium voltage below 35kV, its utilization efficiency can be improved, and the manufacturing cost and operation and maintenance management cost of the metering cabinet can be reduced.

[0040] 2. In the present application, only measurement is performed within the two linear error bands of large and small ratio ranges. Since the current transformer ratio can reach a ratio difference of 2 to 50 times across the range, it can adapt to the power generation and consumption needs of an ultra-wide load range, and solves the problem that the existing electric energy metering devices may have inaccurate electric energy metering due to nonlinear exceeding the limit space such as missed measurement and under-measurement when dealing with ultra-wide load range and cross-range ratio power consumption.

[0041] 3. In the present application, automatic switching of the electric energy metering device is realized under different working conditions. Whether switching from large to small or from small to large, it can ensure that the secondary circuit of the current transformer will not be open to avoid the hazard of high voltage in the secondary circuit of the current transformer. At the same time, it reduces the manufacturing and operation and maintenance costs of the electric energy metering device and improves its utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0043] Figure 1A schematic flow chart of a method for dividing a current transformer error interval for cross-range measurement provided in an embodiment of the present application;

[0044] Figure 2 This is a schematic diagram of the linear error limit measurement interval of the 0.5S / 0.2S level current transformer in the cross-range measurement in the first embodiment of the present application;

[0045] Figure 3 A schematic diagram showing a comparison of the error limit measurement intervals of the State Grid Corporation of China's enterprise standard 0.5SS / 0.2SS level and the national standard 0.5S / 0.2S level current transformers in the cross-range measurement in the first embodiment of the present application;

[0046] Figure 4 This is a schematic diagram of the structure of the current transformer in the second embodiment of the present application;

[0047] Figure 5 This is a schematic diagram of the linear error limit measurement interval of the 0.2S-level 30A / 5A-400A / 5A current transformer in the cross-range measurement in the second embodiment of the present application;

[0048] Figure 6 This is a schematic diagram of the structure of the current transformer in the third embodiment of the present application;

[0049] Figure 7 This is a schematic diagram of the linear error limit measurement range of the 0.2S-level 20A / 5A-400A / 5A current transformer in the cross-range measurement in Example 3 of the present application. DETAILED DESCRIPTION

[0050] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0051] Embodiment 1

[0052] like Figure 1 As shown, the method for dividing the error interval of a current transformer for cross-range measurement provided in the first embodiment of the present application includes:

[0053] S1, a current transformer with multiple ratio ranges is arranged in the electric energy metering circuit;

[0054] S2, constructing an error limit band of the current transformer according to the rated current of the set working range of the current transformer;

[0055] S3, collecting the change of secondary current of current transformer;

[0056] S4, based on the change of the secondary current of the current transformer and the error limit band, the ratio range is switched through the current transformer online switching device;

[0057] The switching process is: when the secondary current of the current transformer is greater than the maximum value of the error limit band, it switches to a large load current ratio; when the secondary current of the current transformer is less than the minimum value of the error limit band, it switches to a small load current ratio.

[0058] Specifically, the multiple ratio ranges may be: multiple ratio ranges formed by matching a common primary closed loop and multiple secondary taps.

[0059] In this embodiment, the current transformer is an S-class current transformer.

[0060] Specifically, the definition of the S-class current transformer is derived from: the special-purpose measuring current transformer referred to in Table 202 of "GB20840.2-2014 Transformers Part 2 Supplementary Technical Requirements for Current Transformers", namely the so-called S-class current transformer.

[0061] In this embodiment, according to the error characteristics of the current transformer, for the S-class current transformer characteristics commonly used in power grid electric energy metering, the error curves of the in-phase component error (i.e., ratio difference) and the orthogonal component error (i.e., phase difference) are basically straight and relatively stable in the range of 20% to 120% of the rated current, and when the rated current is less than 20% or greater than 120%, the error curve shows a trend of expanding and increasing sharply; as shown in Table 1, according to relevant national standards (national standard "GB 20840.2-2014 Transformer Part 2 Supplementary Technology of Current Transformer" and national metrological verification regulations "JJG According to the provisions of "1189.3-2022 Measuring Transformers Part 3: Power Current Transformers", the operating range of the S-class current transformer with the smallest normal error fluctuation is between 20% and 120% of the rated current. The error curve in this range is basically linear. For the 0.2S-class and 0.5S-class current transformers commonly used in electric energy metering, the ratio difference error limits are all less than or equal to ±0.2% or ±0.5%, and the phase error limits are all less than or equal to the corresponding 10' and 30'.

[0062] Table 1: The national standard "GB20840.2-2014 Transformers Part 2 Supplementary Technical Requirements for Current Transformers" stipulates the ratio difference and phase difference limits of special-purpose measuring current transformers (0.2S and 0.5S grades)

[0063]

[0064] In Table 1, ±(') represents the phase difference.

[0065] Based on the above characteristics, this embodiment constructs an error limit band of the current transformer; specifically, the error limit band of the current transformer is: 20% to 120% of the rated secondary current of the current transformer working range;

[0066] The maximum value of the error limit band is: 120% of the rated secondary current of the current transformer working range;

[0067] The minimum value of the error limit band is: 20% of the rated secondary current of the current transformer working range.

[0068] In this embodiment, based on the ratio difference and phase difference of 0.5S-class current transformer and 0.2S-class current transformer commonly used for electric energy metering measurement in the power system field as shown in Table 1, the following is drawn: Figure 2 The diagram shows a comparison of each ratio error limit measurement interval in which the errors of 0.5S and 0.2S current transformers in cross-range measurement are linear; in the diagram: the ratio error (relative error of the in-phase component) and phase error (relative error of the quadrature component) limit measurement intervals of 0.5S and 0.2S current transformers with relatively maximum and minimum range ratio accuracy levels are compared across the non-metering interval. The purpose is to measure electric energy in the metering intervals at both ends of the ratio range under relatively maximum and minimum loads, while the non-metering interval in the middle is not measured, so as to avoid missed measurement, under-measurement and over-measurement caused by the ferromagnetic characteristics of the transformer coil package. The error curve changes significantly when the relative maximum and minimum loads change, thereby maintaining fairness and justice among the three parties of power generation, power supply and power consumption.

[0069] In the present embodiment, only measurement is performed within the two linear error bands of the large and small ratio ranges. Since the current transformer ratio can reach a ratio difference of 2 to 50 times across the range, it can adapt to the power generation and consumption needs of an ultra-wide load range, and solves the problem of inaccurate power metering caused by nonlinear exceeding the limit space such as missed measurement and under-measurement when existing power metering devices process ultra-wide load range and cross-range ratio power consumption.

[0070] Figure 3 The figure shows the comparison of the error limit range of the current transformer of the State Grid Corporation of China's enterprise standard 0.5SS / 0.2SS level and the national standard 0.5S / 0.2S level. Figure 2 The same 0.5S / 0.2S cross-range compound ratio current transformer that meets national standards as shown can safely and worry-freely measure within the minimum linear error range under relatively large and small loads through its peripheral current transformer online switching device, thereby achieving precise measurement across the specified range.

[0071] In cross-range electric energy metering, this embodiment adopts a current transformer with multiple ratio ranges to achieve metering within the linear error band with the smallest error fluctuation, and adopts a current transformer online switching device to judge the current load situation by collecting the change of the secondary current of the current transformer, and switch the current transformer ratio range to ensure that electric energy can be accurately measured under any circumstances; in this embodiment, the secondary current can be divided into a small load current and a large load current, and the process of the secondary current rising is the conversion of the small load current to the large load current, and the process of the secondary current falling is the conversion of the large load current to the small load current; therefore, the switching process is: when the small load current of the current transformer rises to 120% of the rated value, it switches to the large load current ratio; when the large load current of the current transformer drops to 20% of the rated value, it switches to the small load current ratio, and the accurate measurement between the ratio conversions can meet the electric energy metering needs under different loads.

[0072] In this embodiment, during the bidirectional metering process, it is necessary to simultaneously collect the phase signals of the voltage transformer and the current transformer, compare and determine the power flow direction, and then decide the conversion ratio gear.

[0073] Furthermore, in a power scenario with periodic load transformation, the switching process further includes:

[0074] The process of switching from a large load current ratio to a small load current ratio needs to be performed after the load current is reduced;

[0075] The process of switching from a small load current ratio to a large load current ratio needs to be performed before the load current increases.

[0076] In this embodiment, for non-periodic load change scenarios, it is necessary to monitor the changes in the sampled secondary current in real time. According to the theoretical characteristics that the error curve of the current transformer is linear in the range of 20%-120%, a switching process is set: when the secondary current is less than 20% of the rated current, it is switched to a small ratio, and when the secondary current exceeds 120% of the rated current, it is switched to a large ratio, so as to ensure that the electric energy is measured in a reasonable range of the linearity of the metering error and achieve the purpose of fair, just and reasonable metering; for the scenario of periodic load changes, a process is set: the conversion from a large ratio to a small ratio must be switched after the load drops, and the conversion from a small ratio to a large ratio must be switched before the load increases, so as to ensure the safety of the power grid.

[0077] In this embodiment, automatic switching of the electric energy metering device is realized under different working conditions. No matter switching from large to small or from small to large, it can ensure that the secondary circuit of the current transformer will not be open, so as to avoid the high voltage hazard caused by the open circuit of the secondary circuit of the current transformer. At the same time, the manufacturing and operation and maintenance costs of the electric energy metering device are reduced, and its utilization efficiency is improved.

[0078] The method for dividing the error interval of the current transformer for cross-range measurement provided in this embodiment can ensure the accuracy and reliability of electric energy metering under a large range of load changes in medium voltage below 35kV, and perform electricity metering within the error limit band (linear interval of error limit) of relatively large and small ratio ranges. It can adapt to the two-way metering needs of power generation or power consumption in an ultra-wide load range, and avoid the problem of missed metering and inaccurate measurement.

[0079] In addition, when dealing with large-range load changes and bidirectional metering issues in medium voltage below 35kV, the current transformer online switching device can switch the ratio range under different working conditions, which can improve its utilization efficiency and reduce the manufacturing cost and operation and maintenance management cost of the metering cabinet.

[0080] Embodiment 2

[0081] In this embodiment, the structure of the current transformer includes: a primary winding and a secondary winding;

[0082] The primary winding includes: a primary polarity end P1 and a primary non-polarity end P2;

[0083] The secondary winding comprises: a secondary polarity end and a plurality of secondary non-polarity ends to obtain different transformation ratios; the secondary polarity end is matched with any non-polarity end of the secondary winding to form a plurality of transformation ratio ranges respectively.

[0084] This embodiment provides a 0.2S class 30A / 5A-400A / 5A multiple ratio cross-range current transformer, whose secondary winding adopts a multi-tap method according to the cross-range ratio multiple; in order to ensure the accuracy stability and reliability of the 0.2S class current transformer, the minimum ampere-turns designed in combination with the magnetic properties of the iron core is 150 ampere-turns; Figure 4 As shown, the primary winding uses a group of four oxygen-free copper bars with a cross-section of 1mm×30mm that can ensure that the current carrying capacity is 120% of the primary rated current of 400A, that is, 480A, through the annular iron core for 5 turns, the start is connected to the primary polarity terminal P1, and the end is connected to the primary non-polarity terminal P2; the secondary winding uses enameled wire to connect the start to the secondary polarity terminal S1, then evenly pass through the annular iron core for 30 turns, and then the end is connected to the first and secondary non-polarity terminals S2, and then continue to evenly pass through the annular iron core for 370 turns, a total of 400 turns to meet the end connection of 400 ampere turns. To the second secondary non-polarity terminal S3, so that the polarity terminal S1 on the secondary side and the first secondary non-polarity terminal S2 tap correspond to the current transformer ratio of 30A / 5A, and the polarity terminal S1 on the secondary side and the second secondary non-polarity terminal S3 tap correspond to the current transformer ratio of 400A / 5A; the cross-range current transformer ratio spanning multiple is 13.33 times, and the same current transformer can accurately measure electric energy within the error linear range of 20% to 120% of the rated current of the 30A / 5A range and the 400A / 5A range respectively.

[0085] The schematic diagram of the linear error limit measurement range of the 0.2S class 30A / 5A-400A / 5A current transformer is as follows Figure 5 As shown; similarly, 0.5S-level 30A / 5A-400A / 5A multiple-ratio cross-range current transformer or other multiple-ratio cross-range current transformers of other accuracy levels can also implement the same technical solution, which will not be repeated here.

[0086] Embodiment 3

[0087] In this embodiment, the structure of the current transformer includes: a primary winding and a secondary winding;

[0088] The primary winding comprises: a first winding, the first winding is composed of a plurality of turns of coil, the starting end of the first turn of coil is connected to the polarity end P11 of the first winding, the ending end of the last turn of coil passes through the second winding and is connected to the non-polarity end P22 of the first winding, and the first winding and the second winding share a primary circuit;

[0089] The secondary winding includes: a secondary polarity end S11 and a plurality of secondary non-polarity ends;

[0090] The secondary polarity end of the first winding is connected in parallel with the secondary polarity end S11 of the second winding;

[0091] The secondary polarity end S11 matches the primary winding with different secondary non-polarity ends to form different transformation ratio ranges.

[0092] This embodiment provides a 0.2S class 20A / 5A-400A / 5A multi-ratio cross-range current transformer, which uses a common primary conductor to form a common primary circuit and multiple windings with different turns with multiple cores. The secondary winding uses different ampere-turns according to the transformation ratio and accuracy requirements, and all secondary polarity ends are connected in parallel to the common and other non-polarity ends. In order to ensure the stability and reliability of the 0.2S level accuracy, combined with the magnetic properties of the core, the ampere-turns of the small transformation ratio 20A / 5A winding are designed to be 120 ampere-turns, and the ampere-turns of the large transformation ratio 400A / 5A winding are designed to be 400 ampere-turns, such as Figure 6As shown, the current transformer in this embodiment can be formed by a group of four oxygen-free copper bars with a cross-section of 1mm×30mm, which can ensure that the total current carrying capacity is 120% of the primary rated current of 400A, that is, 480A, through the ring core with 6 turns to form the first winding, the beginning of which is connected to the polarity terminal P11, and then one turn through the second winding to form two windings sharing the primary loop, and the end is directly connected to the non-polarity terminal P22; the first secondary winding is connected to the polarity terminal S11 with an enameled wire, and then evenly passed through the ring core for 24 turns and connected to the first secondary non-polarity terminal S22, and the beginning of the second secondary winding enameled wire is also connected to the polarity terminal P11. The polarity terminal S11 is then evenly wound around the end of 80 turns of the second winding annular core and connected to the second non-polarity terminal S33 of the secondary side, so that the polarity terminal S11 and the first non-polarity terminal S22 taps on the secondary side correspond to a current transformer ratio of 20A / 5A, and the polarity terminal S11 and the second non-polarity terminal S33 taps on the secondary side correspond to a current transformer ratio of 400A / 5A; the cross-range current transformer ratio spans 20 times, and the same current transformer can accurately measure electric energy within the error linear range of 20% to 120% of the rated current of the 20A / 5A range and the 400A / 5A range respectively.

[0093] In particular, such a cross-range current transformer has the risk of secondary open circuit when used alone, and must be used in conjunction with a ratio online switching device. Before one of the ratio ranges is connected to the loop, the ratio online switching device needs to be used to short-circuit the secondary end of the other winding. The schematic diagram of the linear error limit measurement range of the 0.5S class 20A / 5A-400A / 5A current transformer is shown in the figure below: Figure 7 As shown; similarly, 0.5S-level 20A / 5A-400A / 5A multiple-ratio cross-range current transformers or other multiple-ratio cross-range current transformers of other accuracy levels can also implement the same technical solution.

[0094] The embodiment of the present application also provides a current transformer error interval division device for cross-range measurement, comprising:

[0095] A cross-range current transformer, which is arranged in an electric energy metering circuit and has multiple ratio ranges;

[0096] A construction unit, used for constructing an error limit band of the current transformer according to the rated current of the set working range of the current transformer;

[0097] A collection unit, used for collecting changes in the secondary current of the current transformer;

[0098] Cross-range current transformer online switching equipment, used to switch the current transformer ratio range based on the change of the current transformer secondary current and the error limit band;

[0099] The switching process is as follows: when the secondary current of the current transformer is greater than the maximum value of the error limit band, it switches to a large load current ratio; when the secondary current of the current transformer is less than the minimum value of the error limit band, it switches to a small load current ratio.

[0100] Wherein, the maximum value of the error limit band is: more than 120% of the rated secondary current;

[0101] The minimum value of the error limit band is: less than 20% of the rated secondary current.

[0102] The present application also provides an electronic device, including:

[0103] memory; processor; and computer program;

[0104] The computer program is stored in the memory and is configured to be executed by the processor to implement the method as described above.

[0105] An embodiment of the present application further provides a computer-readable storage medium on which a computer program is stored; the computer program is executed by a processor to implement the method described above.

[0106] In summary, the current transformer of the present application can maintain high-precision metering performance under a wide range of load changes, which can improve the operating efficiency and stability of the power system for the power system; at the same time, the present application can effectively solve the problem of electric energy metering of renewable energy power generation such as wind power and hydropower, especially when dealing with reverse power consumption in dry wind and dry water seasons, it can also perform accurate metering, which can improve the economic benefits of renewable energy power generation in the field of renewable energy power generation; in addition, the present application can realize automatic switching of the range of the electric energy metering device under different working conditions, which can improve the intelligence level of the power grid and reduce the operating cost of the power grid in the field of smart grids; the current transformer of the present application can have a ratio difference of 2 to 50 across the range, which can adapt to the power generation and consumption needs of an ultra-wide load range, which can reduce electricity costs for power users and improve the level of fair and just electric energy metering management.

[0107] This application can be widely used in power systems, new energy power generation, smart grids and other fields.

[0108] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0109] 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, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0110] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0111] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing 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.

[0112] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0113] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for dividing the error interval of a current transformer for cross-range measurement, characterized in that: include: S1, a current transformer with multiple ratio ranges is arranged in the electric energy metering circuit; S2, constructing the error limit band of the current transformer according to the rated secondary current of the set current transformer working range; S3, collecting the change of secondary current of current transformer; S4, based on the change of the secondary current of the current transformer and the error limit band, the ratio range is switched through the current transformer online switching device; The switching process is as follows: when the secondary current of the current transformer is greater than the maximum value of the error limit band, switching to a large load current ratio; When the secondary current of the current transformer is less than the minimum value of the error limit band, it switches to a small load current ratio.

2. The method for dividing the error interval of a current transformer for cross-range measurement according to claim 1, characterized in that: In a power scenario with periodic load changes, the switching process also includes: The process of switching from a large load current ratio to a small load current ratio needs to be performed after the load current is reduced; The process of switching from a small load current ratio to a large load current ratio needs to be performed before the load current increases.

3. The method for dividing the error interval of a current transformer for cross-range measurement according to claim 1, characterized in that: The error limit band of the current transformer is: 20% to 120% of the rated secondary current of the current transformer working range; The maximum value of the error limit band is: 120% of the rated secondary current of the current transformer working range; The minimum value of the error limit band is: 20% of the rated secondary current of the current transformer working range.

4. The method for dividing the error interval of a current transformer for cross-range measurement according to claim 1, characterized in that: The structure of the current transformer includes: a primary winding and a secondary winding; The primary winding includes: a primary polarity end P1 and a primary non-polarity end P2; The secondary winding comprises: a secondary polarity end and a plurality of secondary non-polarity ends to obtain different transformation ratios; the secondary polarity end is matched with any non-polarity end of the secondary winding to form a plurality of transformation ratio ranges respectively.

5. The method for dividing the error interval of a current transformer for cross-range measurement according to claim 1, characterized in that: The structure of the current transformer includes: a primary winding and a secondary winding; The primary winding includes: a first winding, the first winding is composed of a plurality of turns of coil, the starting end of the first turn of coil is connected to the polarity end P11 of the first winding, the ending end of the last turn of coil passes through the second winding and is connected to the non-polarity end P22 of the first winding, and the first winding or the second winding shares a primary circuit; The secondary winding includes: a secondary polarity end S11 and a plurality of secondary non-polarity ends; The secondary polarity end of the first winding is connected in parallel with the secondary polarity end S11 of the second winding; The secondary polarity end S11 matches the primary winding with different secondary non-polarity ends to form different transformation ratio ranges.

6. The method for dividing the error interval of a current transformer for cross-range measurement according to claim 1, characterized in that: The current transformer is an S-class current transformer.

7. A current transformer error interval division device for cross-range measurement, characterized in that: include: A cross-range current transformer, which is arranged in an electric energy metering circuit and has multiple ratio ranges; A construction unit, used for constructing an error limit band of the current transformer according to a rated secondary current of a set working range of the current transformer; A collection unit, used for collecting changes in the secondary current of the current transformer; Cross-range current transformer online switching equipment, used to switch the current transformer ratio range based on the change of the current transformer secondary current and the error limit band; The switching process is as follows: when the secondary current of the current transformer is greater than the maximum value of the error limit band, switching to a large load current ratio; When the secondary current of the current transformer is less than the minimum value of the error limit band, it switches to a small load current ratio.

8. An electronic device, characterized in that: include: Memory; processor; and computer programs; The computer program is stored in the memory and is configured to be executed by the processor to implement the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon; the computer program is executed by a processor to implement the method according to any one of claims 1 to 6.

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