Secondary voltage circuit abnormal parallel detection device based on current injection method

Abstract

The present invention relates to the technical field of electric power equipment, and specifically discloses a secondary voltage circuit abnormal parallel detection device based on a current injection method, comprising: a first bus circuit, the first bus circuit comprising a first primary side and a first secondary side; a second bus circuit, the second bus circuit comprising a second primary side and a second secondary side; the first primary side and the second primary side are connected in parallel; a first micro-current transformer, the first micro-current transformer is used to sense the line current of the first secondary side; a signal generating circuit, the signal generating circuit comprises a throw-in / out switch and a signal resistor connected in series, and the second secondary side is connected in series with the signal generating circuit. The present invention provides a secondary voltage circuit abnormal parallel detection device based on a current injection method, which is used to detect secondary voltage abnormal parallel circuits without power outages, so as to avoid the risk of electric shock accidents and avoid the expansion of the scope of equipment failure.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power equipment, and in particular to a secondary voltage circuit abnormal parallel detection device based on a current injection method. Background Art

[0002] Generally, take two busbars as an example, see Figure 1 The primary sides of the first bus loop 1 and the second bus loop 2 are connected in parallel, and the secondary sides of the first bus loop 1 and the second bus loop 2 are disconnected from each other. When it is necessary to shut down the first and secondary sides 105 of the first bus loop 1 for maintenance, it is only necessary to disconnect the first and secondary circuit breakers 104 on the first bus loop 1.

[0003] However, see Figure 2 If there is an abnormal parallel circuit 7 between the secondary sides of the first bus circuit 1 and the second bus circuit 2, even if the first and second circuit breakers 104 are disconnected, the first and second sides 105 of the first bus circuit 1 will still have current flowing in through the second secondary side 205 of the second bus circuit 2 and the abnormal parallel circuit 7. Since it is unknown whether the abnormal parallel circuit 7 exists in actual work, the operator will only disconnect the first and second circuit breakers 104 during normal operation. At this time, if there is an abnormal parallel circuit 7, there is a risk of electric shock, and the abnormal parallel circuit 7 is likely to expand the scope of equipment failure.

[0004] In recent years, substations have frequently experienced the situation where the secondary voltage side of the bus voltage transformer (hereinafter referred to as "PT") reversely transmits power to the outage bus during the 220kV bus outage. The reverse power transmission on the secondary side will cause the secondary circuit current of the voltage transformer to increase, leading to the tripping of the secondary circuit breaker of the voltage transformer of the operating bus, damage to the voltage transformer, and other problems, and ultimately causing the protection device to malfunction or refuse to operate due to the loss of voltage input.

[0005] Abnormal paralleling of the secondary voltage circuit is the main cause of reverse power transmission on the secondary voltage side. Devices such as voltage paralleling devices and voltage switching devices have the risk of causing abnormal paralleling of the secondary voltage circuit, and the electrical quantity changes very little when the PT secondary paralleling occurs in the primary paralleling mode. The protection device cannot send alarms for all paralleling situations, which makes it difficult to find the hidden danger of PT secondary error paralleling during equipment operation. Reverse charging is prone to occur during power outages, or the previous busbar loses pressure before the hidden danger of PT secondary error paralleling is eliminated, and the operation of the PT and secondary circuit breaker of the other busbar will be affected, which will cause the protection device to malfunction or refuse to operate.

[0006] Therefore, it is necessary to propose a live detection device for abnormal parallel secondary voltage circuits, which is used to detect abnormal parallel secondary voltage circuits without power outage, so as to avoid the risk of electric shock accidents and avoid the expansion of the scope of equipment failure. Summary of the invention

[0007] One object of the present invention is to provide a secondary voltage circuit abnormal parallel detection device based on current injection method, which is used to detect secondary voltage abnormal parallel circuits without power outage, so as to avoid the risk of electric shock accidents and avoid the expansion of equipment failure range.

[0008] To achieve the above objectives, the present invention provides a secondary voltage circuit abnormal parallel detection device based on current injection method, comprising:

[0009] A first busbar loop, the first busbar loop comprising a first primary side and a first secondary side;

[0010] A second bus circuit, the second bus circuit comprising a second primary side and a second secondary side; the first primary side and the second primary side are connected in parallel;

[0011] A first micro current transformer, the first micro current transformer is used to sense the line current of the first secondary side;

[0012] A signal generating circuit comprises a throw-in / out switch and a signal resistor connected in series, and the second secondary side is connected in series with the signal generating circuit.

[0013] Preferably, it also includes:

[0014] A second micro current transformer, wherein the second micro current transformer is used for sensing the line current of the second secondary side.

[0015] Preferably, the first micro-current transformer and the second micro-current transformer are both open-type clamp meters.

[0016] Preferably, the measuring ranges of the first micro current transformer and the second micro current transformer are both 0 mA to 200 mA, and the accuracy is both below ±0.05 mA.

[0017] Preferably, the accuracy of the first micro current transformer and the second micro current transformer are both below ±0.05mA.

[0018] Preferably, the single-phase resistance of the signal resistor is above 10 kΩ.

[0019] Preferably, the impedance value of the signal resistor is adjustable.

[0020] Preferably, it further comprises a control display module, which comprises a display screen, a control circuit module, a human-computer interaction module and a power supply module.

[0021] The beneficial effects of the present invention are: providing a secondary voltage circuit abnormal parallel detection device based on the current injection method, which can judge whether there is an abnormal parallel circuit between the first secondary side and the second secondary side by comparing the change of the current value displayed by the first micro-current transformer before and after the switch is opened and closed. It is simple and convenient, and can effectively avoid the risk of electric shock accidents and avoid the expansion of the scope of equipment failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative labor.

[0023] Figure 1 A busbar connection schematic diagram without abnormal parallel loops provided as background technology;

[0024] Figure 2 A busbar connection schematic diagram with an abnormal parallel circuit provided as background technology;

[0025] Figure 3 A schematic structural diagram of a secondary voltage circuit abnormality parallel detection device based on a current injection method provided in an embodiment.

[0026] In the figure:

[0027] 1. First bus circuit; 101. First primary side; 102. First primary circuit breaker; 103. First voltage transformer; 104. First secondary circuit breaker; 105. First secondary side;

[0028] 2. Second bus circuit; 201. Second primary side; 202. Second primary circuit breaker; 203. Second voltage transformer; 204. Second secondary circuit breaker; 205. Second secondary side;

[0029] 3. The first micro-current transformer; 4. The second micro-current transformer; 5. The on / off switch; 6. The signal resistor; 7. The abnormal parallel circuit. DETAILED DESCRIPTION

[0030] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0032] See also Figure 3 This embodiment provides a secondary voltage circuit abnormal parallel detection device based on current injection method, including a first bus circuit 1, a second bus circuit 2, a first micro current transformer 3 and a signal generating circuit. The first bus circuit 1 includes a first primary side 101, a first primary circuit breaker 102, a first voltage transformer 103, a first secondary circuit breaker 104 and a first secondary side 105 connected in series. The second bus circuit 2 includes a second primary side 201, a second primary circuit breaker 202, a second voltage transformer 203, a second secondary circuit breaker 204 and a second secondary side 205 connected in series; the first primary side 101 and the second primary side 201 are connected in parallel. The first micro current transformer 3 is used to sense the line current of the first secondary side 105. The signal generating circuit includes a throw-in / out switch 5 and a signal resistor 6 connected in series, and the second secondary side 205 is connected in series with the signal generating circuit.

[0033] It should be noted that the working principle of the secondary voltage circuit abnormal parallel detection device based on the current injection method is as follows:

[0034] ① At the beginning, the throw-in / out switch 5 is in the off state. At this time, since the load connected to the first secondary side 105 is basically in a stable state, the current displayed by the first micro-current transformer 3 is basically stable;

[0035] ② Close the throw-in / out switch 5 to connect the signal resistor 6 to the second bus circuit 2;

[0036] ③ If there is no abnormal parallel loop 7 between the first secondary side 105 and the second secondary side 205, closing the throw-in / out switch 5 has no effect on the load connected to the first secondary side 105, so the current flowing through the first secondary side 105 should not change, that is, the current displayed by the first current transformer is almost unchanged; if there is an abnormal parallel loop 7 between the first secondary side 105 and the second secondary side 205, the signal generating circuit will be electrically connected to the first primary side 101 through the abnormal parallel loop 7. After closing the throw-in / out switch 5, it is equivalent to increasing the load connected to the first secondary side 105, and the current displayed by the first microcurrent transformer 3 will be significantly reduced; therefore, by comparing the decrease in the current value displayed by the first microcurrent transformer 3 before and after closing the throw-in / out switch 5, it can be determined whether there is an abnormal parallel loop 7 between the first secondary side 105 and the second secondary side 205.

[0037] Correspondingly, if the throw-in / out switch 5 is in a closed state at the beginning, when the throw-in / out switch 5 is closed, if the current value displayed by the first micro-current transformer 3 remains almost unchanged, it means that there is no abnormal parallel circuit 7; if the current value displayed by the first micro-current transformer 3 increases by an amount reaching a preset value, it means that there is an abnormal parallel circuit 7.

[0038] The secondary voltage circuit abnormal parallel detection device based on the current injection method provided in this embodiment can determine whether there is an abnormal parallel circuit 7 between the first secondary side 105 and the second secondary side 205 by comparing the changes in the current value displayed by the first micro-current transformer 3 before and after the opening and closing of the switch 5. It is simple and convenient, and can effectively avoid the risk of electric shock accidents and prevent the expansion of the scope of equipment failure.

[0039] In this embodiment, the secondary voltage circuit abnormal parallel detection device further includes a second micro current transformer 4 , and the second micro current transformer 4 is used to sense the line current of the second secondary side 205 .

[0040] It can be understood that regardless of whether there is an abnormal parallel circuit 7, the load connected to the second secondary side 205 before and after the on-off switch 5 will change, so the current value displayed by the second microcurrent transformer 4 should change. If the current value displayed by the second microcurrent transformer 4 before and after the on-off switch 5 does not change, it means that the signal generating circuit may be broken or the signal resistor 6 is short-circuited, etc. Therefore, the second microcurrent transformer 4 can be used to observe and determine whether the signal resistor 6 is normally connected to the current circuit, so as to avoid misjudgment by only observing the first microcurrent transformer 3.

[0041] Preferably, the first micro-current transformer 3 and the second micro-current transformer 4 are both open-type clamp meters.

[0042] Specifically, the clamp meter structure is easy to operate and convenient to install and disassemble on the line.

[0043] In this embodiment, the measuring ranges of the first micro-current transformer 3 and the second micro-current transformer 4 are both 0 mA to 200 mA, and the precisions are both below ±0.05 mA, and the precisions of the first micro-current transformer 3 and the second micro-current transformer 4 are both below ±0.05 mA.

[0044] The high-precision micro-current transformer range used in this embodiment is consistent with the secondary current of the bus voltage transformer of the substation with a voltage level of 10kV and above, that is, 0mA-200mA, and the accuracy should meet the current monitoring requirements of the signal generating circuit, that is, below ±0.05mA. Within this range and accuracy, it is easy to make an accurate judgment on whether there is an abnormal parallel circuit 7.

[0045] Furthermore, the single-phase resistance of the signal resistor 6 is greater than 10 kΩ.

[0046] Specifically, the signal resistor 6 is a three-phase resistor, and the current signal to the ground (or to the neutral line of the secondary circuit of the voltage transformer) is generated in the circuit by switching the signal resistor 6 on and off through the switch 5. In order to ensure the safety and reliability of the secondary system of the voltage transformer, the impedance value of the signal resistor 6 should be equivalent to the normal secondary load of the busbar voltage transformer, that is, the single-phase resistance value is generally above 10kΩ, ensuring that the signal current is less than 6mA

[0047] Preferably, the impedance of the signal resistor 6 is adjustable.

[0048] Specifically, the adjustable resistance value can facilitate the signal circuit to be applied to the voltage transformer secondary system of different substations

[0049] The secondary voltage circuit abnormal parallel detection device also includes a control display module, which includes a display screen, a control circuit module, a human-computer interaction module and a power supply module.

[0050] Preferably, the control circuit module is also connected to the first micro-current transformer 3 and the second micro-current transformer 4, and can read the current values ​​sensed by the first micro-current transformer 3 and the second micro-current transformer 4.

[0051] Specifically, by clicking or touching the human-computer interaction module to control the circuit module to input instructions, the control circuit module controls the opening and closing of the throw-in / out switch 5 according to the instructions, changes the resistance value of the signal resistor 6, and judges whether there is an abnormal parallel circuit 7 based on the current change information before and after the signal circuit is thrown and withdrawn, and finally displays the judgment result on the display screen.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A secondary voltage circuit abnormal parallel detection device based on current injection method, characterized in that: include: A first busbar loop, the first busbar loop comprising a first primary side and a first secondary side; A second bus circuit, the second bus circuit comprising a second primary side and a second secondary side; the first primary side and the second primary side are connected in parallel; A first micro current transformer, the first micro current transformer is used to sense the line current of the first secondary side; A signal generating circuit, the signal generating circuit comprising a throw-in / out switch and a signal resistor connected in series, the second secondary side being connected in series with the signal generating circuit; the single-phase resistance of the signal resistor being above 10 kΩ; A second micro current transformer, wherein the second micro current transformer is used for sensing the line current of the second secondary side.

2. The secondary voltage circuit abnormal parallel detection device based on current injection method according to claim 1 is characterized in that: The first micro-current transformer and the second micro-current transformer are both open-type clamp meters.

3. The secondary voltage circuit abnormal parallel detection device based on current injection method according to claim 2 is characterized in that: The measuring ranges of the first micro current transformer and the second micro current transformer are both 0 mA to 200 mA.

4. The secondary voltage circuit abnormal parallel detection device based on current injection method according to claim 3 is characterized in that: The accuracy of the first micro current transformer and the second micro current transformer are both below ±0.05mA.

5. The secondary voltage circuit abnormal parallel detection device based on current injection method according to claim 1, characterized in that: The impedance value of the signal resistor is adjustable.

6. The secondary voltage circuit abnormal parallel detection device based on current injection method according to claim 1, characterized in that: It also includes a control display module, which includes a display screen, a control circuit module, a human-computer interaction module and a power supply module.

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