CN110988747A - Secondary voltage loop abnormity parallel detection device based on current injection method - Google Patents
Secondary voltage loop abnormity parallel detection device based on current injection method Download PDFInfo
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- CN110988747A CN110988747A CN201911168626.2A CN201911168626A CN110988747A CN 110988747 A CN110988747 A CN 110988747A CN 201911168626 A CN201911168626 A CN 201911168626A CN 110988747 A CN110988747 A CN 110988747A
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Abstract
The invention relates to the technical field of power equipment, and particularly discloses a secondary voltage loop abnormal parallel detection device based on a current injection method, which comprises the following steps: a first bus circuit comprising a first primary side and a first secondary side; a 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 for sensing line current at the first secondary side; and the signal generating loop comprises a switching switch and a signal resistor which are connected in series, and the second secondary side is connected with the signal generating loop in series. The invention provides a secondary voltage circuit abnormal parallel detection device based on a current injection method, which is used for finding a secondary voltage abnormal parallel circuit under the condition of no power failure so as to avoid the risk of electric shock accidents and avoid the expansion of the equipment fault range.
Description
Technical Field
The invention relates to the technical field of power equipment, in particular to a secondary voltage loop abnormity parallel detection device based on a current injection method.
Background
Generally, taking two-section buses as an example, referring to fig. 1, the primary sides of the first bus circuit 1 and the second bus circuit 2 are connected in parallel, the secondary sides of the first bus circuit 1 and the second bus circuit 2 are disconnected from each other, and when power failure needs to be performed on the first secondary side 105 of the first bus circuit 1, only the first secondary air switch 104 on the first bus circuit 1 needs to be disconnected.
However, referring to fig. 2, if there is an abnormal parallel circuit 7 between the secondary sides of the first and second bus circuits 1 and 2, even if the first secondary air switch 104 is turned off, there is a current flowing in the first secondary side 105 of the first bus circuit 1 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 the actual operation, the operator only turns off the first secondary air switch 104 during the normal operation, and at this time, if the abnormal parallel circuit 7 exists, there is a risk of an electric shock accident, and the abnormal parallel circuit 7 is likely to expand the equipment failure range.
In recent years, in a substation, a situation frequently occurs in which a secondary voltage side of a bus voltage transformer (hereinafter, abbreviated as "PT") reversely transmits power to a power failure bus during power failure and transmission of a 220kV bus. The secondary side reverse power transmission causes the current of a secondary loop of the voltage transformer to be increased, so that the problems of secondary idle tripping of the voltage transformer of the running bus, damage of the voltage transformer and the like are caused, and finally the protection device is misoperated or refused to operate due to the loss of voltage input quantity.
Abnormal parallel of secondary voltage circuits is a main cause of reverse power transmission on the secondary voltage side. The device such as the voltage paralleling device, the voltage switching device and the like has the risk of causing abnormal paralleling of a secondary voltage loop, the change of the electric quantity is very small when PT secondary paralleling occurs in a primary paralleling mode, the protection device cannot give an alarm for all paralleling conditions, further the hidden danger of PT secondary false paralleling is difficult to find in the operation process of equipment, reverse charging is easy to occur when power is cut off at present, or the hidden danger of PT secondary false paralleling does not eliminate the voltage loss of the previous section of bus, the PT and secondary open operation of the other section of bus are affected, and further the protection device is mistakenly operated or refused to operate.
Therefore, there is a need to provide a live line detection device for detecting an abnormal parallel secondary voltage circuit without power outage, so as to avoid the risk of electric shock accidents and the expansion of the equipment failure range.
Disclosure of Invention
An object of the present invention is to provide a secondary voltage circuit abnormal parallel detection device based on a current injection method, which is used for finding a secondary voltage abnormal parallel circuit without power failure, so as to avoid the risk of electric shock accidents and avoid the expansion of equipment failure range.
To achieve the above object, the present invention provides a device for detecting abnormal parallel secondary voltage circuits by current injection method, comprising:
a first bus circuit comprising a first primary side and a first secondary side;
a 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 for sensing line current at the first secondary side;
and the signal generating loop comprises a switching switch and a signal resistor which are connected in series, and the second secondary side is connected with the signal generating loop in series.
Preferably, the method further comprises the following steps:
a second micro current transformer for sensing line current on the second secondary side.
Preferably, the first micro-current transformer and the second micro-current transformer are both open type clamp gauges.
Preferably, the ranges of the first micro-current transformer and the second micro-current transformer are both 0mA-200mA, and the precision is below +/-0.05 mA.
Preferably, the precision of the first micro-current transformer and the precision of the second micro-current transformer are both below +/-0.05 mA.
Preferably, the single-phase resistance of the signal resistor is more than 10k omega.
Preferably, the reactance value of the signal resistor is adjustable.
Preferably, the intelligent control system further comprises a control display module, wherein the control display module comprises a display screen, a control circuit module, a human-computer interaction module and a power supply module.
The invention has the beneficial effects that: the secondary voltage loop abnormal parallel detection device based on the current injection method can judge whether an abnormal parallel loop exists between the first secondary side and the second secondary side or not by comparing the change conditions of the current values displayed by the first micro-current transformers before and after the on-off switch, is simple and convenient, and can effectively avoid the risk of electric shock accidents and avoid the expansion of equipment fault range.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
FIG. 1 is a schematic diagram of a bus bar connection without an abnormal parallel circuit provided in the background art;
FIG. 2 is a schematic diagram of bus connection with abnormal parallel circuit provided in the background art;
fig. 3 is a schematic structural diagram of a secondary voltage loop abnormal parallel detection device based on a current injection method according to an embodiment.
In the figure:
1. a first bus bar loop; 101. a first primary side; 102. a first primary air switch; 103. a first voltage transformer; 104. a first secondary air switch; 105. a first secondary side;
2. a second bus circuit; 201. a second primary side; 202. second primary air opening; 203. a second voltage transformer; 204. second air opening; 205. a second secondary side;
3. a first microcurrent transformer; 4. a second microcurrent transformer; 5. a switch is turned on and off; 6. a signal resistor; 7. an abnormal parallel loop.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Referring to fig. 3, the present embodiment provides a device for detecting an abnormal parallel secondary voltage circuit based on a current injection method, which includes a first bus circuit 1, a second bus circuit 2, a first micro-current transformer 3, and a signal generating circuit. The first busbar loop 1 comprises a first primary side 101, a first primary air switch 102, a first voltage transformer 103, a first secondary air switch 104 and a first secondary side 105 connected in series. The second bus circuit 2 comprises a second primary side 201, a second primary air switch 202, a second voltage transformer 203, a second secondary air switch 204 and a second secondary side 205 which are connected in series; the first primary side 101 and the second primary side 201 are connected in parallel. The first microcurrent transformer 3 is used for sensing the line current of the first secondary side 105. The signal generating circuit comprises a switch 5 and a signal resistor 6 which are connected in series, and the second secondary side 205 is connected in series with the signal generating circuit.
The operation principle of the secondary voltage circuit abnormality parallel detection device based on the current injection method is as follows:
①, the on/off switch 5 is in an off state when the current displayed by the first micro-current transformer 3 is substantially stable because the load connected to the first secondary side 105 is substantially in a stable state;
②, closing the on/off switch 5 to connect the signal resistor 6 to the second bus circuit 2;
③ if there is no abnormal parallel circuit 7 between the first secondary side 105 and the second secondary side 205, the closing of the on/off switch 5 has no effect on the load connected to the first secondary side 105, so there should be no change in the current flowing through the first secondary side 105, i.e. the current displayed by the first current transformer is almost unchanged, if there is an abnormal parallel circuit 7 between the first secondary side 105 and the second secondary side 205, the signal generating circuit is electrically connected to the first primary side 101 through the abnormal parallel circuit 7, after the on/off switch 5 is closed, the current displayed by the first micro current transformer 3 is significantly reduced, which is equivalent to increasing the load connected to the first secondary side 105, therefore, the presence or absence of the abnormal parallel circuit 7 between the first secondary side 105 and the second secondary side 205 can be determined by comparing the reduction of the current value displayed by the first micro current transformer 3 before and after the on/off switch 5 is closed.
Correspondingly, if the on-off switch 5 is in a closed state at the beginning, the on-off switch 5 is closed, and if the current value displayed by the first micro-current transformer 3 is almost unchanged, the abnormal parallel loop 7 does not exist; if the current value displayed by the first micro current transformer 3 increases by a preset value, it indicates that an abnormal parallel loop 7 exists.
The secondary voltage loop abnormal parallel detection device based on the current injection method provided by the embodiment can judge whether the abnormal parallel loop 7 exists between the first secondary side 105 and the second secondary side 205 by comparing the change conditions of the current values displayed by the first micro-current transformers 3 before and after the on-off switch 5, is simple and convenient, and can effectively avoid the risk of electric shock accidents and avoid the expansion of the equipment fault range.
In this embodiment, the parallel detection device for secondary voltage loop abnormality further includes a second micro-current transformer 4, where the second micro-current transformer 4 is configured to sense a line current of the second secondary side 205.
It can be understood that, no matter whether the abnormal parallel circuit 7 exists, the load connected to the second secondary side 205 before and after the on/off switch 5 changes, so the current value displayed by the second micro-current transformer 4 should change, and if the current value displayed by the second micro-current transformer 4 before and after the on/off switch 5 does not change, it indicates that the signal generating circuit may be open or the signal resistor 6 is short-circuited, and the like, so the second micro-current transformer 4 can be used for observing and judging whether the signal resistor 6 is normally connected to the current circuit, so as to avoid misjudgment caused by observing only the first micro-current transformer 3.
Preferably, the first micro-current transformer 3 and the second micro-current transformer 4 are both open type clamp gauges.
Particularly, the clamp meter structure is convenient to operate and assemble and disassemble on a line.
In this embodiment, the ranges of the first micro-current transformer 3 and the second micro-current transformer 4 are both 0mA to 200mA, the accuracies are both below ± 0.05mA, and the accuracies of the first micro-current transformer 3 and the second micro-current transformer 4 are both below ± 0.05 mA.
The high-precision micro-current transformer range adopted by the embodiment is consistent with the secondary current of a bus voltage transformer with the voltage class of 10kV and above of a transformer substation, namely 0mA-200mA, the precision meets the current amount monitoring requirement of a signal generation loop, namely below +/-0.05 mA, and the existence of an abnormal parallel loop 7 is easily and accurately judged under the range and the precision range.
Further, the single-phase resistance of the signal resistor 6 is more than 10k Ω.
Specifically, the signal resistor 6 is a three-phase resistor, and a current signal to the ground (or to the zero line of the secondary circuit of the voltage transformer) is generated in the circuit by switching on/off the on/off switch 5 and switching off the signal resistor 6. In order to ensure the safety and reliability of a secondary system of the voltage transformer, the impedance value of the signal resistor 6 is equivalent to the normal secondary load of the bus voltage transformer, namely, the single-phase resistance value is generally more than 10k omega, and the signal current is ensured to be less than 6mA
Preferably, the reactance value of the signal resistor 6 is adjustable.
In particular, the adjustable resistance value can facilitate the signal loop to be suitable for the secondary system of the voltage transformer of different transformer substations
The device for detecting the secondary voltage loop abnormity in parallel further comprises a control display module, wherein the control display module comprises a display screen, a control circuit module, a human-computer interaction module and a power supply module.
Preferably, the control circuit module is further connected with the first micro-current transformer 3 and the second micro-current transformer 4 in a point manner, and can read current values sensed by the first micro-current transformer 3 and the second micro-current transformer 4.
Specifically, a control circuit module inputs an instruction by clicking or touching the man-machine interaction module, the control circuit module controls the on-off of the on-off switch 5 and changes the resistance value of the signal resistor 6 according to the instruction, whether an abnormal parallel circuit 7 exists or not is judged according to the current change information before and after the signal circuit is turned on and off, and finally the judgment result is displayed on a display screen.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A secondary voltage loop abnormal parallel detection device based on a current injection method is characterized by comprising the following steps:
a first bus circuit comprising a first primary side and a first secondary side;
a 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 for sensing line current at the first secondary side;
and the signal generating loop comprises a switching switch and a signal resistor which are connected in series, and the second secondary side is connected with the signal generating loop in series.
2. The apparatus for detecting an abnormal parallel secondary voltage circuit according to claim 1, further comprising:
a second micro current transformer for sensing line current on the second secondary side.
3. The current injection method-based secondary voltage loop abnormal parallel detection device as claimed in claim 2, wherein the first micro current transformer and the second micro current transformer are both open type clamp gauges.
4. The current injection method-based secondary voltage loop abnormal parallel detection device as claimed in claim 3, wherein the ranges of the first micro current transformer and the second micro current transformer are both 0mA-200mA, and the precision is below +/-0.05 mA.
5. The current injection method-based secondary voltage loop abnormal parallel detection device as claimed in claim 4, wherein the accuracy of the first micro current transformer and the second micro current transformer is both below ± 0.05 mA.
6. The apparatus for detecting an abnormal parallel secondary voltage circuit according to claim 1, wherein the signal resistor has a single-phase resistance of 10k Ω or more.
7. The current injection method-based secondary voltage loop abnormal parallel detection device as claimed in claim 6, wherein the reactance value of the signal resistor is adjustable.
8. The current injection method-based secondary voltage loop abnormal parallel detection device according to claim 1, further comprising a control display module, wherein the control display module comprises a display screen, a control circuit module, a man-machine interaction module and a power supply module.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911168626.2A CN110988747A (en) | 2019-11-25 | 2019-11-25 | Secondary voltage loop abnormity parallel detection device based on current injection method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911168626.2A CN110988747A (en) | 2019-11-25 | 2019-11-25 | Secondary voltage loop abnormity parallel detection device based on current injection method |
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| CN110988747A true CN110988747A (en) | 2020-04-10 |
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| CN201911168626.2A Pending CN110988747A (en) | 2019-11-25 | 2019-11-25 | Secondary voltage loop abnormity parallel detection device based on current injection method |
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