A current loop detection device and method for a total step-down substation

Abstract

A total step-down substation current loop detection device and method, the device includes a current measuring device, a transformer primary side switch, a transformer primary side current transformer, a transformer secondary side switch, and a transformer secondary side current transformer; the measuring ends of the transformer primary side current transformer and the transformer secondary side current transformer are connected to the current measuring device. It also includes a transformer secondary side short-circuit switch and a secondary side short-circuit busbar. By controlling the short-circuit busbar of the transformer and the switch connected to it, the short-circuit test current is used as the primary side test current of the current transformer, and the transformer high-voltage side current flows through the incoming switch and the transformer high-voltage side switch, and the transformer low-voltage side current flows through the low-voltage side switch and the feed-out switch, but the integrity of the current transformer secondary loop can be checked, and the transformation ratio and polarity of the current transformer can be checked.

Description

Technical Field

[0001] The present invention relates to the technical field of current detection, and in particular to a current loop detection device and method for a total step-down substation. Background Art

[0002] In the secondary circuit integrity and polarity inspection test of the current transformer in the main step-down substation, since there are many secondary current circuits, each circuit needs to be measured separately and the wiring needs to be changed repeatedly, so the workload is large and the efficiency is low. In addition, it is impossible to determine whether the polarity of the secondary wiring of the three-phase current transformer is consistent, the polarity of the differential protection cannot be determined, and it is impossible to verify whether the current circuit is correct. Summary of the invention

[0003] In order to solve the technical problems in the background technology, the present invention provides a current loop detection device and method for a total step-down substation. By controlling the short-circuit busbar of the transformer and the switch connected thereto, the short-circuit test current is used as the primary side test current of the current transformer. The high-voltage side current of the transformer flows through the incoming switch and the high-voltage side switch of the transformer, and the low-voltage side current of the transformer flows through the low-voltage side switch and the outgoing switch. In this way, the current transformer of the incoming switch of the total step-down substation, the current transformer of the high-voltage side switch of the transformer, the current transformer of the low-voltage side switch of the transformer and the current transformer of the outgoing switch can be checked at the same time, and not only the integrity of the secondary loop of the current transformer can be checked, but also the transformation ratio and polarity of the current transformer can be checked.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A current loop detection device for a total step-down substation comprises a current measuring device, a transformer primary side switch, a transformer primary side current transformer, a transformer secondary side switch, and a transformer secondary side current transformer; the measuring ends of the transformer primary side current transformer and the transformer secondary side current transformer are both connected to the current measuring device.

[0006] It also includes a transformer secondary side short-circuit switch and a secondary side short-circuit busbar, a first opening button, a first closing button, a second opening button, a second closing button, a third opening button, and a third closing button.

[0007] The secondary side of the transformer is connected to the secondary side short-circuit switch and connected to the secondary side short-circuit busbar through the secondary side short-circuit switch;

[0008] The first opening button is connected in series with the opening coil of the primary switch of the transformer and then connected to both ends of the control power supply;

[0009] The first closing button is connected in series with the closing coil of the primary side switch of the transformer and then connected to the two ends of the control power supply;

[0010] The second opening button is connected in series with the opening coil of the secondary switch of the transformer and then connected to both ends of the control power supply;

[0011] The second closing button is connected in series with the closing coil of the secondary side switch of the transformer and then connected to the two ends of the control power supply;

[0012] The third opening button is connected in series with the opening coil of the short-circuit switch on the secondary side of the transformer and then connected to both ends of the control power supply;

[0013] The third closing button is connected in series with the closing coil of the short-circuit switch on the secondary side of the transformer and then connected to the two ends of the control power supply.

[0014] Furthermore, it also includes a first opening indicator light, a first closing indicator light, a second opening indicator light, a second closing indicator light, a third opening indicator light, and a third closing indicator light;

[0015] The first opening indicator light is connected in series with the normally closed contact of the primary switch of the transformer and then connected to both ends of the control power supply;

[0016] The first closing indicator light is connected in series with the normally open contact of the primary side switch of the transformer and then connected to the two ends of the control power supply;

[0017] The second opening indicator light is connected in series with the normally closed contact of the secondary switch of the transformer and then connected to both ends of the control power supply;

[0018] The second closing indicator light is connected in series with the normally open contact of the transformer secondary side switch and then connected to both ends of the control power supply;

[0019] The third opening indicator light is connected in series with the normally closed contact of the short-circuit switch on the secondary side of the transformer and then connected to both ends of the control power supply;

[0020] The third closing indicator light is connected in series with the normally open contact of the short-circuit switch on the secondary side of the transformer and then connected to the two ends of the control power supply.

[0021] A detection method for a current loop detection device of a total step-down substation, comprising the following steps:

[0022] 1) First, calculate the short-circuit current on the secondary side when 400V voltage is applied to the primary side of the transformer according to the nameplate parameters of the transformer. Select the short-circuit busbar section at the short-circuit point according to this current. Calculate the high-voltage side current of the transformer according to the short-circuit current and transformer parameters. Select the test power cable and power switch accordingly. If the current on the high-voltage side is too small or the current on the low-voltage side is too large, it can be adjusted by changing the gear of the transformer;

[0023] 2) Secondly, before the test, check that all live circuits are well insulated, the switch opening and closing operations are completed, the secondary current circuit is calibrated correctly, there is no open circuit, the display instrument and integrated protector display are normal, the power supply is connected according to the technical requirements, the short-circuit busbar is tightened, and the switch is preset to the specified position as required;

[0024] 3) During the test, measure the primary current with a clamp meter and compare it with the calculated value. Check the secondary current amplitude and phase through the display instrument and integrated protector, check the transformer differential current, and check whether the transformation ratio and polarity of the relevant transformer are correct. There is no need to shut down the power if there is no abnormality during the test, because the cables and short-circuit busbars have been verified, so there is enough time to check each related current loop one by one to ensure accuracy;

[0025] 4) After the final test is completed, remove the test power supply and short-circuit busbar and restore the system.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] By controlling the short-circuit busbar of the transformer and the switch connected to it, the short-circuit test current is used as the primary test current of the current transformer. The high-voltage side current of the transformer flows through the incoming switch and the high-voltage side switch of the transformer, and the low-voltage side current of the transformer flows through the low-voltage side switch and the outgoing switch. In this way, the current transformer of the incoming switch of the total step-down substation, the current transformer of the high-voltage side switch of the transformer, the current transformer of the low-voltage side switch of the transformer and the current transformer of the outgoing switch can be checked at the same time. Not only the integrity of the secondary circuit of the current transformer can be checked, but also the transformation ratio and polarity of the current transformer can be checked. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention relates to a single-line diagram of a primary circuit system of a substation;

[0029] Figure 2 This is a short-circuit diagram of the transformer secondary side;

[0030] Figure 3 It is the connection diagram of the current measuring device and the current transformer;

[0031] Figure 4 It is an electrical diagram of the switch and indicator light control circuit of the present invention. DETAILED DESCRIPTION

[0032] The specific implementation modes provided by the present invention are described in detail below with reference to the accompanying drawings.

[0033] like Figure 1-4 As shown, see Figure 1 and Figure 4 , Figure 4 For Figure 1 The control diagram of the left line of the example is taken as an example, and the control of the right line is the same as the left. A total step-down substation current loop detection device, including a current measuring device RCS-9671C (see Figure 3), transformer primary side switch 103DL (taking the left side as an example), transformer primary side current transformer 1LH-4LH (taking the left side as an example), transformer secondary side switch 201DL, transformer secondary side current transformer 5LH-8LH; see Figure 3 , transformer primary side current transformer 1LH-4LH( Figure 3 1LH is used as an example) and the transformer secondary side current transformer 5LH-8LH ( Figure 3 The measuring ends of the 5LH are connected to the current measuring device.

[0034] like Figure 1 As shown ( Figure 1 Taking the left line of as an example), it also includes a transformer secondary side short-connection switch 2001DL and a secondary side short-connection busbar M. The secondary side of the transformer is connected to the secondary side short-connection switch 2001DL and connected to the secondary side short-connection busbar M through the secondary side short-connection switch 2001DL;

[0035] like Figure 4 As shown ( Figure 1 Taking the left side line as an example), it also includes a first opening button 103TA1, a first closing button 103TA2, a second opening button 201TA1, a second closing button 201TA2, a third opening button 2001TA1, and a third closing button 2001TA2.

[0036] The first opening button 103TA1 is connected in series with the opening coil 103TQ of the transformer primary switch 103DL and then connected to both ends of the control power supply DC220V;

[0037] The first closing button 103TA2 is connected in series with the closing coil 103HQ of the primary side switch 103DL of the transformer and then connected to both ends of the control power supply DC220V;

[0038] The second opening button 201TA1 is connected in series with the opening coil 201TQ of the transformer secondary side switch 201DL and then connected to both ends of the control power supply;

[0039] The second closing button 201TA2 is connected in series with the closing coil 201HQ of the transformer secondary side switch 201DL and then connected to both ends of the control power supply;

[0040] The third opening button 2001TA1 is connected in series with the opening coil 2001TQ of the short-circuit switch 2001DL on the secondary side of the transformer and then connected to both ends of the control power supply;

[0041] The third closing button 2001TA2 is connected in series with the closing coil 2001HQ of the short-circuit switch 2001DL on the secondary side of the transformer and then connected to the two ends of the control power supply.

[0042] It also includes a first opening indicator light 103LD, a first closing indicator light 103HD, a second opening indicator light 201LD, a second closing indicator light 201HD, a third opening indicator light 2001LD, and a third closing indicator light 2001HD;

[0043] The first opening indicator light 103LD is connected in series with the normally closed contact of the transformer primary side switch 103DL and then connected to the two ends of the control power supply;

[0044] The first closing indicator light 103HD is connected in series with the normally open contact of the transformer primary side switch 103DL and then connected to the two ends of the control power supply;

[0045] The second opening indicator light 201LD is connected in series with the normally closed contact of the transformer secondary side switch 201DL and then connected to the two ends of the control power supply;

[0046] The second closing indicator light 201HD is connected in series with the normally open contact of the transformer secondary side switch 201DL and then connected to the two ends of the control power supply;

[0047] The third opening indicator light 2001LD is connected in series with the normally closed contact of the short-circuit switch 2001DL on the secondary side of the transformer and then connected to both ends of the control power supply;

[0048] The third closing indicator light 2001HD is connected in series with the normally open contact of the short-circuit switch 2001DL on the secondary side of the transformer and then connected to the two ends of the control power supply.

[0049] A detection method for a current loop detection device of a total step-down substation, comprising the following steps:

[0050] 1) First, calculate the short-circuit current on the secondary side when 400V voltage is applied to the primary side of the transformer according to the nameplate parameters of the transformer. Select the short-circuit busbar section at the short-circuit point according to this current. Calculate the high-voltage side current of the transformer according to the short-circuit current and transformer parameters. Select the test power cable and power switch accordingly. If the current on the high-voltage side is too small or the current on the low-voltage side is too large, it can be adjusted by changing the gear of the transformer;

[0051] 2) Secondly, before the test, check that all live circuits are well insulated, the switch opening and closing operations are completed, the secondary current circuit is calibrated correctly, there is no open circuit, the display instrument and integrated protector display are normal, the power supply is connected according to the technical requirements, the short-circuit busbar is tightened, and the switch is preset to the specified position as required;

[0052] 3) During the test, measure the primary current with a clamp meter and compare it with the calculated value. Check the secondary current amplitude and phase through the display instrument and integrated protector, check the transformer differential current, and check whether the transformation ratio and polarity of the relevant transformer are correct. There is no need to shut down the power if there is no abnormality during the test, because the cables and short-circuit busbars have been verified, so there is enough time to check each related current loop one by one to ensure accuracy;

[0053] 4) After the final test is completed, remove the test power supply and short-circuit busbar and restore the system.

[0054] The device of the present invention can simultaneously measure the secondary currents of three groups of current transformers by using a detection device connected in series in a current loop, and the closing and opening of the switches on the high-voltage side and the low-voltage side of the main transformer are controlled by buttons, and the switch status is displayed by an indicator light. The primary current of the current transformer is obtained by using the short-circuit busbar of the transformer to obtain the short-circuit current. A three-phase AC 400V power supply is applied to the high-voltage side of the transformer through an incoming line switch and a high-voltage side switch of the transformer. The secondary side of the transformer is short-circuited in three phases after passing through a low-voltage side switch of the transformer and a feeder switch, and a short-circuit current is generated as a test current. The integrity of the secondary circuits of the incoming line current, the high-voltage side current of the transformer, and the low-voltage side current of the transformer is checked by using a current loop detection device, which involves a metering loop, a measuring loop, and a protection loop. At the same time, it can be checked whether the transformation ratio of each current transformer is correct, whether the polarity is correct, and whether the transformer differential protection parameter settings are correct.

[0055] The above embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A detection method for a current loop detection device of a total step-down substation, wherein the detection device of the detection method comprises a current measuring device, a transformer primary side switch, a transformer primary side current transformer, a transformer secondary side switch, and a transformer secondary side current transformer; the measuring ends of the transformer primary side current transformer and the transformer secondary side current transformer are both connected to the current measuring device; It is characterized in that The detection device of the detection method also includes a transformer secondary side short-connection switch and a secondary side short-connection busbar, a first opening button, a first closing button, a second opening button, a second closing button, a third opening button, and a third closing button; The secondary side of the transformer is connected to the secondary side short-circuit switch and connected to the secondary side short-circuit busbar through the secondary side short-circuit switch; The first opening button is connected in series with the opening coil of the primary switch of the transformer and then connected to both ends of the control power supply; The first closing button is connected in series with the closing coil of the primary side switch of the transformer and then connected to the two ends of the control power supply; The second opening button is connected in series with the opening coil of the secondary switch of the transformer and then connected to both ends of the control power supply; The second closing button is connected in series with the closing coil of the secondary side switch of the transformer and then connected to the two ends of the control power supply; The third opening button is connected in series with the opening coil of the short-circuit switch on the secondary side of the transformer and then connected to both ends of the control power supply; The third closing button is connected in series with the closing coil of the short-circuit switch on the secondary side of the transformer and then connected to both ends of the control power supply; The detection method comprises the following: 1) First, calculate the secondary short-circuit current when 400V voltage is applied to the primary side of the transformer according to the nameplate parameters of the transformer. Select the secondary short-circuit busbar section at the short-circuit point according to this current. Calculate the high-voltage side current of the transformer according to the short-circuit current and transformer parameters. Select the test power cable and power switch accordingly. If the high-voltage side current is too small or the low-voltage side current is too large, adjust it by changing the gear of the transformer; 2) Secondly, before the test, check that all live circuits are well insulated, the switch opening and closing operations are completed, the secondary current circuit is calibrated correctly, there is no open circuit, the display instrument and integrated protector display are normal, the power supply is connected according to the technical requirements, the secondary side short-circuit busbar is tightened, and the switch is preset to the specified position as required; 3) During the test, measure the primary current with a clamp meter and compare it with the calculated value. Check the secondary current amplitude and phase through the display instrument and integrated protector, check the transformer differential current, and check whether the transformation ratio and polarity of the relevant transformer are correct. There is no need to shut down the power if there is no abnormality during the test, because the cable and the secondary side short-circuit busbar have been verified, so there is enough time to check each related current loop one by one to ensure accuracy; 4) After the final test is completed, remove the test power supply and secondary side short-circuit busbar and restore the system.

2. The detection method of a current loop detection device for a total step-down substation according to claim 1 is characterized in that: It also includes a first opening indicator light, a first closing indicator light, a second opening indicator light, a second closing indicator light, a third opening indicator light, and a third closing indicator light; The first opening indicator light is connected in series with the normally closed contact of the primary switch of the transformer and then connected to both ends of the control power supply; The first closing indicator light is connected in series with the normally open contact of the primary side switch of the transformer and then connected to the two ends of the control power supply; The second opening indicator light is connected in series with the normally closed contact of the secondary switch of the transformer and then connected to both ends of the control power supply; The second closing indicator light is connected in series with the normally open contact of the transformer secondary side switch and then connected to both ends of the control power supply; The third opening indicator light is connected in series with the normally closed contact of the short-circuit switch on the secondary side of the transformer and then connected to both ends of the control power supply; The third closing indicator light is connected in series with the normally open contact of the short-circuit switch on the secondary side of the transformer and then connected to the two ends of the control power supply.

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