10kV current transformer transformation ratio detector

Abstract

The utility model relates to the technical field of electric power, in particular to a transformation ratio detector for a 10kV current transformer. The current transformer is sleeved on a primary bus, an incoming line terminal of a metering winding of the current transformer is connected with an outgoing line terminal of the metering electric energy meter, an outgoing line terminal of the metering winding of the current transformer is connected with an incoming line terminal of the metering electric energy meter, and an incoming line terminal of the measuring winding of the current transformer is connected with an outgoing line terminal of the measuring ampere meter; a wire outlet terminal of the current transformer measuring winding is connected with a wire inlet terminal of the measuring ammeter. The current transformer is installed on the primary bus, the current transformer is connected with the measuring ammeter and the metering electric energy meter, and transformation ratio checking can be carried out under the non-stop condition according to the measuring ammeter and the metering electric energy meter.

Description

Technical Field

[0001] The utility model relates to the technical field of electric power. Background Art

[0002] In the power system, 10kV power users with a capacity greater than 160kVA generally use the two-wattmeter method to measure electric energy. Two voltage transformers and two current transformers need to be configured to convert the high voltage and large current on the primary side into the low voltage and small current on the secondary side, which is connected to the watt-hour meter through the metering secondary circuit to form a three-phase three-wire connection system. The power consumption of the user within a certain period of time is obtained by multiplying the watt-hour value read by the watt-hour meter by the voltage and current transformer ratio (i.e., the comprehensive ratio). Since the abnormal change ratio of the current transformer is often found after the equipment has been energized and operating on site, according to the safety regulations, it is strictly prohibited to open the box body and perform any operations on the equipment during operation. The change ratio inspection cannot be carried out by visual inspection. Therefore, when performing the change ratio inspection, it is necessary to cut off the power supply of all the user's substation equipment, hang a grounding wire on the current transformer to be measured to complete the discharge, and then perform the change ratio inspection operation. After the inspection, the power supply is restored.

[0003] When the existing method performs power-on and power-off operations, there is a safety risk of misoperation. At the same time, when a person enters the box body to observe the change ratio of the current transformer, there are risks of mechanical injury and electric shock, and it is necessary to strictly follow the safety regulations and operating procedures. For important loads, high-risk users, power plants and other users, power outages will cause major safety accidents, and it is impossible to cut off the power supply to the users for inspection. In addition, for users with distributed photovoltaics, after the power supply on the mains side is cut off, the electric energy generated by the photovoltaic side still transmits to the power grid through the primary side. Therefore, it is also necessary to shut down the photovoltaic side before the inspection can be carried out. If it cannot be shut down, the change ratio inspection cannot be carried out. Summary of the Utility Model

[0004] In order to solve the problem in the prior art that the change ratio inspection can only be carried out after shutting down, the utility model provides a 10kV current transformer change ratio detector.

[0005] The technical solution adopted by the utility model to achieve the above purpose is:

[0006] A 10kV current transformer change ratio detector, the current transformer 1 is sleeved on the primary bus 2. The incoming line terminal of the metering winding 3 of the current transformer 1 is connected to the outgoing line terminal of the metering watt-hour meter 5, and the outgoing line terminal of the metering winding 3 of the current transformer is connected to the incoming line terminal of the metering watt-hour meter 5. The incoming line terminal of the measuring winding 4 of the current transformer 1 is connected to the outgoing line terminal of the measuring ammeter 6, and the outgoing line terminal of the measuring winding 4 of the current transformer is connected to the incoming line terminal of the measuring ammeter 6.

[0007] A first split-type current transformer 7 is installed on the line connecting the current transformer 1 and the metering watt-hour meter 5, and a second split-type current transformer 8 is installed on the line connecting the current transformer 1 and the measuring ammeter 6. The first split-type current transformer 7 and the second split-type current transformer 8 are connected to a data collector 9.

[0008] The current transformer 1 is a split-type current transformer.

[0009] The data collector 9 is connected to an intelligent terminal 10.

[0010] The advantages of the present utility model compared with the prior art are as follows:

[0011] By installing the current transformer on the primary busbar, the current transformer is connected to the measuring ammeter and the metering watt-hour meter, and the turns ratio inspection can be carried out without shutting down according to the measuring ammeter and the metering watt-hour meter. Description of the Drawings

[0012] Figure 1 It is a schematic diagram of a 10kV current transformer turns ratio detector of the present utility model.

[0013] In the figure: 1, current transformer; 2, primary busbar; 3, metering winding; 4, measuring winding; 5, metering watt-hour meter; 6, measuring ammeter; 7, first split-type current transformer; 8, second split-type current transformer; 9, data collector; 10, intelligent terminal. Detailed Embodiment

[0014] The turns ratio of the 10kV voltage transformer is fixed at 10000 / 100, but the turns ratio of the current transformer is formulated according to the newly installed capacity of the user and is not fixed. At the same time, some users will increase or decrease the production load according to their own business conditions, and the corresponding turns ratio of the current transformer also needs to be changed accordingly. Currently, most current transformers are compound-ratio current transformers and single-ratio current transformers. For the compound-ratio transformer, there is an incoming line terminal (1S1) and three outgoing line terminals with increasing turns ratio (i.e., 1S2, 1S3, 1S4) on its metering winding, and a measuring winding with a fixed turns ratio (2S1, 2S2). For the single-ratio transformer, there is only one incoming line terminal (1S1) and a fixed-turns-ratio outgoing line terminal (1S2) on its metering winding, and a measuring winding with a fixed turns ratio (2S1, 2S2).

[0015] During on-site operations, there are phenomena such as the design plan, power supply plan not matching the substation equipment drawings, on-site operators misconnecting or wrongly disconnecting tap changers, equipment manufacturers mismatching transformation ratios, or wrongly selecting transformation ratios during the business expansion process, resulting in the inconsistency between the actual transformation ratio of the current transformer on-site and the transformation ratio of the power supply company's power energy acquisition system. Subsequently, it causes abnormal line losses and abnormal electricity quantities and electricity charges, having an adverse impact on users and the power supply company. Therefore, it is necessary for inspectors to promptly check the correct transformation ratio of the current transformer and restore normal power consumption.

[0016] A 10kV current transformer transformation ratio detector provided by the present utility model is as Figure 1 shown. The current transformer 1 is sleeved on the primary bus 2. The incoming line terminal of the metering winding 3 of the current transformer 1 is connected to the outgoing line terminal of the metering watt-hour meter 5, and the outgoing line terminal of the metering winding 3 of the current transformer is connected to the incoming line terminal of the metering watt-hour meter 5. The incoming line terminal of the measuring winding 4 of the current transformer 1 is connected to the outgoing line terminal of the measuring ammeter 6, and the outgoing line terminal of the measuring winding 4 of the current transformer is connected to the incoming line terminal of the measuring ammeter 6. A first split-type current transformer 7 is installed on the line connecting the current transformer 1 and the metering watt-hour meter 5, and a second split-type current transformer 8 is installed on the line connecting the current transformer 1 and the measuring ammeter 6. The first split-type current transformer 7 and the second split-type current transformer 8 are connected to the data collector 9. The current transformer 1 is a split-type current transformer. The data collector 9 is connected to the intelligent terminal 10. Using split-type current transformers facilitates the installation and disassembly of the transformers.

[0017] Working principle: The currents measured by the metering winding 3 and the measuring winding 4 of the current transformer 1 are both primary currents. The metering winding 3 is connected to the metering watt-hour meter 5 through a wire to form a secondary circuit, and the measuring winding 4 is connected to the measuring ammeter 6 through a wire to form a secondary circuit;

[0018] It is known that: I2 × current multiplication factor = I1, where I1 is the primary current; I2 is the secondary current;

[0019] Therefore, by taking a point on the metering secondary circuit through the first split-type current transformer 7 and measuring the current value passing through this point and multiplying it by the measuring circuit current multiplication factor, the value of the primary current passing through the current transformer at this moment can be obtained.

[0020] That is, I of the metering watt-hour meter × metering secondary circuit multiplication factor (k) = I1

[0021] By taking a point on the measuring secondary circuit through the second split-type current transformer 8 and measuring the current value passing through this point.

[0022] That is, I 测量电流表 × metering secondary circuit multiplication factor = I1

[0023] Then, the metering electric energy meter × the metering secondary circuit multiplier (k) = the measuring ammeter × the metering secondary circuit multiplier, and we get:

[0024]

[0025] The measuring secondary circuit multiplier of the current transformer is a known quantity and is marked below the instrument dial. In summary, in the circuits where the metering secondary circuit and the measuring secondary circuit of the on-site current transformer are connected to the power energy acquisition device, there are obvious wiring traces and wire gaps for measuring instruments to access. Therefore, the method of measuring current parameters on the two circuits is feasible. At the same time, because the rated current on the secondary side of the current transformer is 5A and it does not contact other circuits, the risk is relatively low. Therefore, the staff can operate with confidence.

[0026] Select an open-type current transformer with a transformation ratio of 1 / 1 as the acquisition device for the secondary circuit current. Collect the measurement data of the measuring ammeter 6 and the metering electric energy meter 5 through the data collector 9 and transmit it to the intelligent terminal through WiFi.

[0027] Use an Android industrial tablet to develop a calculation program and a database, and import the existing circuit transformer models into the database. Use the voltage measurement terminal as the power supply for the WiFi data transmission module, and transmit the real-time voltage and current data to the mobile terminal through WiFi connection.

[0028] The staff can check the real-time voltage and current data in the status monitoring program on the mobile terminal, and input three parameters in the transformation ratio calculation program, namely: the metering secondary circuit current value, the measuring secondary circuit current value, and the measuring circuit current multiplier. The calculation program automatically calculates the actual transformation ratio of the on-site current transformer.

[0029] The calculated value of K in [] should be a constant and cannot intuitively display the transformation ratio size. It needs to be converted into the form of * / *. Therefore, the K value needs to be associated with the corresponding transformation ratio size, and the intuitive transformation ratio size is output after the association.

[0030] According to the relevant technical standards of the existing current transformer models and transformation ratios, the corresponding relationship between the transformation ratio and the calculated value is as follows:

[0031]

[0032] Table of the corresponding relationship between K value and transformation ratio

[0033] Since the K value in the table is an integer, but the on-site calculation results may have decimal places. According to a large number of on-site verifications, the calculated value of K is generally close to an integer value. For example, 2.134 or 2.987. That is, if it is close to the smaller value, take the smaller value; if it is close to the larger value, take the larger value. If the median situation occurs, it is generally considered that the measured value is incorrect or the measurement conditions are incorrect, and it is recommended to re-measure.

[0034] Of course, this method is not perfect. If the user is in a no-load or light-load state, the measured current is often an induced current. In this case, the calculated transformation ratio may be inaccurate. The user can be asked to start a part of the load or, if conditions permit, power off to check the transformation ratio. The method described in this article is intended to solve the transformation ratio inspection operation under normal power consumption conditions.

[0035] If the current value measured on-site for any secondary circuit is 0, it indicates that there is an open-circuit fault in the secondary circuit. At this time, the fault should be excluded first. After the normal metering is restored, the transformation ratio inspection can be carried out.

[0036] The present utility model is described through embodiments. Those skilled in the art know that without departing from the spirit and scope of the present utility model, various changes or equivalent substitutions can be made to these features and embodiments. In addition, under the teaching of the present utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present utility model. Therefore, the present utility model is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the protection scope of the present utility model.

Claims

1. A 10kV current transformer ratio detector, characterized in that, The current transformer (1) is sleeved on the primary busbar (2). The incoming line terminal of the metering winding (3) of the current transformer (1) is connected to the outgoing line terminal of the metering watt-hour meter (5), and the outgoing line terminal of the metering winding (3) of the current transformer is connected to the incoming line terminal of the metering watt-hour meter (5). The incoming line terminal of the measuring winding (4) of the current transformer (1) is connected to the outgoing line terminal of the measuring ammeter (6), and the outgoing line terminal of the measuring winding (4) of the current transformer is connected to the incoming line terminal of the measuring ammeter (6).

2. The 10 kV current transformer ratio detector according to claim 1, characterized in that A first split-type current transformer (7) is installed on the line where the current transformer (1) is connected to the metering watt-hour meter (5), and a second split-type current transformer (8) is installed on the line where the current transformer (1) is connected to the measuring ammeter (6). The first split-type current transformer (7) and the second split-type current transformer (8) are connected to the data collector (9).

3. A 10 kV current transformer ratio detector according to claim 1, characterized in that, The current transformer (1) is a split-type current transformer.

4. A 10 kV current transformer ratio detector according to claim 2, characterized in that The data collector (9) is connected to the intelligent terminal (10).

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