CN111694306A - CT secondary circuit multipoint grounding on-line monitoring device and monitoring method thereof - Google Patents
CT secondary circuit multipoint grounding on-line monitoring device and monitoring method thereof Download PDFInfo
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- CN111694306A CN111694306A CN202010543214.9A CN202010543214A CN111694306A CN 111694306 A CN111694306 A CN 111694306A CN 202010543214 A CN202010543214 A CN 202010543214A CN 111694306 A CN111694306 A CN 111694306A
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
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Abstract
The invention discloses a multipoint grounding online monitoring device and a monitoring method of a CT secondary circuit, and the device comprises a point grounding connecting wire, a current transformer, a transmitter U1, a PLC (programmable logic controller), a relay group, a resistor group and an alarm device; the point grounding connection line is connected between a grounding point N of a secondary circuit of the CT and a secondary equipotential ground net M, the current transformer is connected in series on the point grounding connection line, the transmitter U1 is electrically connected with the secondary side of the current transformer, the PLC is electrically connected with the output end of the transmitter U1, and the relay group is used for receiving and executing commands of the PLC. The CT secondary circuit multipoint grounding on-line monitoring device and the monitoring method thereof have simple structure and convenient use, and realize the purpose of monitoring the grounding condition of the grounding point of the CT secondary circuit in real time by adopting the mutual matching arrangement of the PLC program control and the relay; potential safety hazards are timely discovered and eliminated, and safe and stable operation of the unit and the power grid is guaranteed.
Description
Technical Field
The invention relates to the field of CT secondary circuit monitoring, in particular to a CT secondary circuit multipoint grounding on-line monitoring device and a monitoring method thereof.
Background
The secondary side of the current transformer is required to have one grounding point, because if the secondary loop does not have the grounding point, the high voltage on the primary side of the current transformer is transmitted to the secondary side through the ground distributed capacitor between the primary coil and the secondary coil of the current transformer to cause danger to personal equipment, and once the secondary loop is grounded, the ground capacitor on the secondary side is equivalently fixed to be zero potential; if multipoint earthing exists, because the thermal power plant earthing network is not ideal equipotential, potential difference exists among the multipoint, and inaccurate sampling is caused to a protection device or an instrument due to shunting action; meanwhile, once a ground fault occurs, the ground current can form shunt among multiple points, so that the sampling value of the sampled waveform of the protection device is distorted and deviates, and the incorrect action of the protection device is caused.
In actual operation, due to reasons such as equipment upgrading and transformation, secondary circuit insulation aging and the like, two-point or multi-point grounding of a secondary circuit of a current transformer can be caused, so that a unit shutdown or large-area power failure accident caused by CT disconnection alarm, misoperation or refusal operation of a protection device occurs in the operation process, and relay protection operation and maintenance personnel mostly judge that the CT secondary circuit is subjected to multi-point grounding and wiring error through analysis and judgment when serious alarm conditions such as false operation of the protection device or CT disconnection occur, and have no relevant mode method for monitoring the grounding condition of the secondary circuit in real time, so that the potential hazards can not be found in time after the fact is mostly inspected and processed. Meanwhile, a large amount of time is needed for the relay protection operation and maintenance personnel to check, the checking workload is extremely large one by one, the operation randomness is large, the checking effect is low, if the checking is not found, multipoint grounding is formed during thunderstorm or under the influence of lightning current, and the time for processing defects is extremely delayed.
Therefore, a device for accurately judging the multipoint grounding hidden danger of the CT secondary circuit is needed on the premise that the operating CT secondary circuit does not lose the unique grounding point and the normal operation of the relay protection equipment is not influenced.
2013.01.02 discloses a patent with publication number CN202649370U entitled "PT secondary circuit multipoint grounding on-line monitor", which discloses a PT secondary circuit multipoint grounding on-line monitor, comprising a control room one-point grounding connection line (1), a lightning arrester F, a milliammeter a, a knife gate K and a slide rheostat R, which can determine the hidden trouble of multipoint grounding on the premise of ensuring that the operating PT secondary circuit does not lose grounding point and influence the normal operation of the protection equipment, but it monitors the multipoint grounding condition of the PT (voltage transformer) secondary circuit, and it needs to determine whether the multipoint grounding condition occurs by observing the change of the milliammeter, which is very inconvenient, and if the grounding line current returns to cause the signal to disappear, the maintainer cannot know the condition.
In the current CT secondary circuit multipoint grounding fault elimination, the following problems also exist:
1. multipoint earth faults cannot be eliminated in time, and potential safety hazards are easy to exist;
2. failure troubleshooting can not be carried out on the premise of not influencing the normal operation of the relay protection equipment.
Based on the above situation, the invention provides a CT secondary circuit multipoint grounding on-line monitoring device and a monitoring method thereof, which can effectively solve the above problems.
Disclosure of Invention
The invention aims to provide a CT secondary circuit multipoint grounding on-line monitoring device and a monitoring method thereof. The CT secondary circuit multipoint grounding on-line monitoring device and the monitoring method thereof have simple structure and convenient use, and realize the purpose of monitoring the grounding condition of the grounding point of the CT secondary circuit in real time by adopting the mutual matching arrangement of the PLC program control and the relay; potential safety hazards are timely discovered and eliminated, and safe and stable operation of the unit and the power grid is guaranteed.
The invention is realized by the following technical scheme:
the invention provides a multipoint grounding online monitoring device for a CT secondary circuit, which comprises a point grounding connecting wire, a current transformer, a transmitter U1, a PLC (programmable logic controller), a relay group, a resistor group and an alarm device, wherein the point grounding connecting wire is connected with the current transformer;
the one-point grounding connecting line is connected between a grounding point N of a CT secondary loop and a secondary equipotential ground network M, the current transformer is connected in series on the CT one-point grounding connecting line, the transmitter U1 is electrically connected with the secondary side of the current transformer, the PLC is electrically connected with the output end of the transmitter U1, and the relay group is used for receiving and executing PLC control commands;
the resistor group comprises a resistor R0 and a resistor R1;
the alarm device comprises an acousto-optic alarm and an NCS system;
the relay group comprises a relay K1 and a normally open contact K1-1 thereof, a relay KT1 and time-delay normally open contacts KT1-1 and KT1-2 thereof, a relay KT2 and time-delay normally open contacts KT2-1 and KT2-2 thereof, a relay K2 and a normally open contact K2-1 thereof, a relay K3 and a normally open contact K3-1 thereof, a relay K4 and a normally open contact K4-1 thereof, a relay K5 and a normally open contact K5-1 thereof, and a monitoring relay Z1;
the PLC and gate output contact and the relay K1 are connected in series on a direct current power supply;
the relays KT1 and KT2 are connected in parallel and are called as a first parallel group; the normally open contact K1-1 of the relay K1 and the first parallel group are connected in series on a direct current power supply;
the time-delay normally-open contact KT1-1 of the relay KT1 is connected with the time-delay normally-open contact KT2-1 of the relay KT2 in parallel and is called a second parallel group, and the time-delay normally-open contact KT1-2 of the relay KT1 is connected with the time-delay normally-open contact KT2-2 of the relay KT2 in parallel and is called a third parallel group; the two ends of the third parallel group are also connected with a normally open contact K2-1 of a relay K2 in parallel, and the normally closed contacts K3-1 of the second parallel group, the third parallel group, the relay K2 and the relay K3 are sequentially connected on a direct-current power supply in series;
the relay K3, the resistor R0 and the reset button SB are sequentially connected in series on a direct-current power supply;
the PLC output contact D0.1 and the relay K4 are connected in series on a direct current power supply, and a normally open contact K4-1, an audible and visual alarm and a resistor R1 of the relay K4 are sequentially connected in series on the direct current power supply;
the PLC output contact D0.2 and the relay K5 are connected in series on a direct current power supply, and the normally open contact K5-1 of the relay K5 and the multipoint grounding alarm signal of the NCS system are connected in series on the direct current power supply;
both ends of the transmitter U1 and the monitoring relay Z1 are connected to a direct current power supply;
the normally closed contact Z1-1 of the monitoring relay Z1 and a direct current power failure alarm signal of an NCS system are connected in series on a direct current power supply;
preferably, the current transformer is a high-precision split core type current transformer.
According to another aspect of the present invention, there is provided a monitoring method based on a CT secondary circuit multipoint grounding on-line monitoring device, the method comprising the following steps:
step S1: presetting a specific current threshold in the PLC;
step S2: the current transformer collects the current value on the grounding wire in real time;
step S3: the transmitter U1 converts the current value acquired by the current transformer into a current value which can be identified by the PLC controller and transmits the current value to the PLC controller;
step S4: comparing the current value received by the PLC with a preset current threshold value, and judging whether the secondary circuit of the current transformer has a multipoint grounding condition according to the comparison result;
step S5: if the condition of multipoint grounding exists, the PLC controller triggers an alarm device, and the specific steps are as follows:
step S51: the output contact of the AND gate outputs high level to trigger the relay K1 to act, so that the normally open contact K1-1 is closed;
step S52: the normally open contact K1-1 is closed, so that the relays KT1 and KT2 are triggered to act;
step S53: the relay KT1 and the relay KT2 act, so that the time-delay normally-open contacts KT1-1, KT1-2, KT2-1 and KT2-2 are closed in a time-delay manner, and the relay K2 is triggered to act;
step S54: the relay K2 acts, so that the PLC output contacts D0.1 and D0.2 are closed, and the normally open contact K2-1 is closed to form a self-holding loop;
step S55: the PLC output contacts D0.1 and D0.2 are closed, so that the relays K4 and K5 are triggered to act;
step S56: the relays K4 and K5 act, so that normally open contacts K4-1 and K5-1 are closed, a multipoint grounding alarm signal of an audible and visual alarm and an NCS system is triggered, and CT secondary circuit multipoint grounding information is popped up on an NCS display screen.
Step S6: if the multipoint grounding condition does not exist, the PLC controller does not perform other actions.
The invention aims to provide a CT secondary circuit multipoint grounding on-line monitoring device and a monitoring method thereof. The CT secondary circuit multipoint grounding on-line monitoring device and the monitoring method thereof have simple structure and convenient use, and realize the purpose of monitoring the grounding condition of the grounding point of the CT secondary circuit in real time by adopting the mutual matching arrangement of the PLC program control and the relay; potential safety hazards are timely discovered and eliminated, and safe and stable operation of the unit and the power grid is guaranteed.
Preferably, the method further comprises a reset function, and the step S7 is as follows:
step S71: pressing a normally open reset button SB to trigger a relay K3 to act;
step S72: the normally closed contact K3-1 is opened, the relay K2 loop is disconnected, and the alarm signal disappears.
Preferably, the method further comprises a dc power monitoring function, and step S8 is as follows:
step S81: when the direct current power supply disappears, the monitoring relay Z1 loses power, so the normally closed contact Z1-1 is closed;
step S82: the normally closed contact Z1-1 is closed, so that a direct current power failure alarm signal of the NCS system is triggered, and a 'direct current power failure of a CT secondary circuit multipoint grounding alarm device' message is popped up on an NCS display screen.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the CT secondary circuit multipoint grounding on-line monitoring device and the monitoring method thereof have simple structure and convenient use, and realize the purpose of monitoring the grounding condition of the grounding point of the CT secondary circuit in real time by adopting the mutual matching arrangement of the PLC program control and the relay; the potential safety hazard is timely discovered and eliminated, the safe and stable operation of unit and electric wire netting is ensured, and the concrete advantage is as follows:
the multipoint grounding alarm device of the CT secondary circuit has small volume, simple designed circuit and convenient installation;
2. the expandability is strong, for a plurality of CT secondary circuits to be monitored, only a high-precision pincerlike current transformer and a high-precision alternating current transmitter need to be additionally arranged, the installation is convenient, and the method is suitable for various occasions such as a power plant or a transformer substation;
3. the method can timely discover and eliminate potential safety hazards, improve the safety troubleshooting efficiency, and effectively reduce the error rate in manual troubleshooting.
Drawings
FIG. 1 is a schematic diagram of a circuit wiring structure of the current collecting section according to the present invention;
FIG. 2 is a schematic circuit wiring (upper half) structure diagram of the PLC program control part of the present invention;
fig. 3 is a schematic diagram of a circuit wiring (lower half) of the PLC program control section of the present invention.
In the figure: 1-one point grounding connection line; 2-a current transformer; 3-transmitter U1; 4-a PLC controller; 5-audible and visual alarm.
Detailed Description
In order that those skilled in the art will better understand the technical solutions of the present invention, the following description of the preferred embodiments of the present invention is provided in conjunction with specific examples, but it should be understood that the drawings are for illustrative purposes only and should not be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.
Example 1:
as shown in fig. 1 to 3, the present invention provides a CT secondary circuit multipoint grounding on-line monitoring device, which includes a point grounding connection line 1, a current transformer 2, a transmitter U13, a PLC controller 4, a relay group, a resistor group and an alarm device;
the one-point grounding connecting line 1 is connected between a grounding point N of a secondary circuit of the CT and a secondary equipotential ground network M, the current transformer 2 is connected in series on the one-point grounding connecting line 1, the transmitter U13 is electrically connected with the secondary side of the current transformer 2, and the PLC controller 4 is electrically connected with the output end of the transmitter U13; the relay group is used for receiving and executing a PLC controller 4 command;
the resistor group comprises a resistor R0 and a resistor R1;
the alarm device comprises an acousto-optic alarm 5 and an NCS system;
the relay group comprises a relay K1 and a normally open contact K1-1 thereof, a relay KT1 and time-delay normally open contacts KT1-1 and KT1-2 thereof, a relay KT2 and time-delay normally open contacts KT2-1 and KT2-2 thereof, a relay K2 and a normally open contact K2-1 thereof, a relay K3 and a normally open contact K3-1 thereof, a relay K4 and a normally open contact K4-1 thereof, a relay K5 and a normally open contact K5-1 thereof, and a monitoring relay Z1;
the PLC and gate output contact and the relay K1 are connected in series on a direct current power supply;
the relays KT1 and KT2 are connected in parallel and are called as a first parallel group; the normally open contact K1-1 of the relay K1 and the first parallel group are connected in series on a direct current power supply;
the time-delay normally-open contact KT1-1 of the relay KT1 is connected with the time-delay normally-open contact KT2-1 of the relay KT2 in parallel and is called a second parallel group, and the time-delay normally-open contact KT1-2 of the relay KT1 is connected with the time-delay normally-open contact KT2-2 of the relay KT2 in parallel and is called a third parallel group; the two ends of the third parallel group are also connected with a normally open contact K2-1 of a relay K2 in parallel, and the normally closed contacts K3-1 of the second parallel group, the third parallel group, the relay K2 and the relay K3 are sequentially connected on a direct-current power supply in series;
the relay K3, the resistor R0 and the reset button SB are sequentially connected in series on a direct-current power supply;
the PLC output contact D0.1 and the relay K4 are connected in series on a direct current power supply, and a normally open contact K4-1 of a relay K4, the audible and visual alarm 5 and a resistor R1 are sequentially connected in series on the direct current power supply;
the PLC output contact D0.2 and the relay K5 are connected in series on a direct current power supply, and the normally open contact K5-1 of the relay K5 and the multipoint grounding alarm signal of the NCS system are connected in series on the direct current power supply;
both ends of the transmitter U13 and the monitoring relay Z1 are connected to a direct current power supply;
and a normally closed contact Z1-1 of the monitoring relay Z1 and a direct current power failure alarm signal of the NCS system are connected in series on a direct current power supply.
The invention also provides a monitoring method based on the CT secondary circuit multipoint grounding on-line monitoring device, which comprises the following steps:
step S1: a specific current threshold (50mA) is preset in the PLC 4;
step S2: the current transformer 2 collects the current value on the grounding wire in real time;
step S3: the transmitter U13 converts the current value acquired by the current transformer 2 into a current value (4-20 mA) which can be identified by the PLC controller 4 and transmits the current value to the PLC controller 4;
step S4: the PLC 4 compares the received current value with a preset current threshold value thereof, and judges whether the secondary circuit of the current transformer 2 has a multipoint grounding condition according to the comparison result;
step S5: if the condition of multipoint grounding exists, the PLC 4 triggers an alarm device, and the specific steps are as follows:
step S51: the output contact of the AND gate outputs high level to trigger the relay K1 to act, so that the normally open contact K1-1 is closed;
step S52: the normally open contact K1-1 is closed, so that the relays KT1 and KT2 are triggered to act;
step S53: the relays KT1 and KT2 act, two delay time relays are arranged, interference caused by unstable factors caused by environmental factors is prevented, and the outlet relay K2 can be triggered only when the two relays act simultaneously; therefore, the delayed normally-open contacts KT1-1, KT1-2, KT2-1 and KT2-2 are closed in a delayed mode, the relay K2 is triggered to act, and the possibility of misoperation or operation rejection can be effectively avoided by utilizing the two groups of normally-open contacts which are connected in parallel and then connected in series.
Step S54: the relay K2 is operated, so the PLC output contacts D0.1 and D0.2 are closed, the normally open contact K2-1 is closed to form a self-holding loop, and the relay K2 is connected with the normally open contact K2-1 in series to prevent the signal from disappearing due to the return of the current of the grounding wire, so as to remind the operation and maintenance personnel that the grounding is carried out at multiple points once, but the signal is returned due to the change of the load current and other reasons.
Step S55: the PLC output contacts D0.1 and D0.2 are closed, so that the relays K4 and K5 are triggered to act;
step S56: the relays K4 and K5 act, so that normally open contacts K4-1 and K5-1 are closed, a multipoint grounding alarm signal of the audible and visual alarm 5 and the NCS system is triggered, and information of 'CT secondary circuit multipoint grounding' is popped up on the NCS display screen.
Step S6: if the multipoint earthing is not present, the PLC controller 4 does not perform other operations.
The above technical solutions are all understandable to those skilled in the art.
Example 2:
as shown in fig. 1 to 3, the present invention provides a CT secondary circuit multipoint grounding on-line monitoring device, which includes a point grounding connection line 1, a current transformer 2, a transmitter U13, a PLC controller 4, a relay group, a resistor group and an alarm device;
the one-point grounding connecting line 1 is connected between a grounding point N of a secondary circuit of the CT and a secondary equipotential ground network M, the current transformer 2 is connected in series on the one-point grounding connecting line 1, the transmitter U13 is electrically connected with the secondary side of the current transformer 2, and the PLC controller 4 is electrically connected with the output end of the transmitter U13; the relay group is used for receiving and executing a PLC controller 4 command;
the resistor group comprises a resistor R0 and a resistor R1;
the alarm device comprises an acousto-optic alarm 5 and an NCS system;
the relay group comprises a relay K1 and a normally open contact K1-1 thereof, a relay KT1 and time-delay normally open contacts KT1-1 and KT1-2 thereof, a relay KT2 and time-delay normally open contacts KT2-1 and KT2-2 thereof, a relay K2 and a normally open contact K2-1 thereof, a relay K3 and a normally open contact K3-1 thereof, a relay K4 and a normally open contact K4-1 thereof, a relay K5 and a normally open contact K5-1 thereof, and a monitoring relay Z1;
the PLC and gate output contact and the relay K1 are connected in series on a direct current power supply;
the relays KT1 and KT2 are connected in parallel and are called as a first parallel group; the normally open contact K1-1 of the relay K1 and the first parallel group are connected in series on a direct current power supply;
the time-delay normally-open contact KT1-1 of the relay KT1 is connected with the time-delay normally-open contact KT2-1 of the relay KT2 in parallel and is called a second parallel group, and the time-delay normally-open contact KT1-2 of the relay KT1 is connected with the time-delay normally-open contact KT2-2 of the relay KT2 in parallel and is called a third parallel group; the two ends of the third parallel group are also connected with a normally open contact K2-1 of a relay K2 in parallel, and the normally closed contacts K3-1 of the second parallel group, the third parallel group, the relay K2 and the relay K3 are sequentially connected on a direct-current power supply in series;
the relay K3, the resistor R0 and the reset button SB are sequentially connected in series on a direct-current power supply;
the PLC output contact D0.1 and the relay K4 are connected in series on a direct current power supply, and a normally open contact K4-1 of a relay K4, the audible and visual alarm 5 and a resistor R1 are sequentially connected in series on the direct current power supply;
the PLC output contact D0.2 and the relay K5 are connected in series on a direct current power supply, and the normally open contact K5-1 of the relay K5 and the multipoint grounding alarm signal of the NCS system are connected in series on the direct current power supply;
both ends of the transmitter U13 and the monitoring relay Z1 are connected to a direct current power supply;
and a normally closed contact Z1-1 of the monitoring relay Z1 and a direct current power failure alarm signal of the NCS system are connected in series on a direct current power supply.
Further, in another embodiment, the current transformer 2 is a high-precision split core current transformer 2.
The invention also provides a monitoring method based on the CT secondary circuit multipoint grounding on-line monitoring device, which comprises the following steps:
step S1: a specific current threshold value is preset in the PLC 4;
step S2: the current transformer 2 collects the current value on the grounding wire in real time;
step S3: the transmitter U13 converts the current value acquired by the current transformer 2 into a current value which can be identified by the PLC controller 4 and transmits the current value to the PLC controller 4;
step S4: the current value received by the PLC 4 is compared with a preset current threshold value, and whether the condition of multipoint grounding exists in a secondary circuit of the current transformer 2 is judged according to the comparison result;
step S5: if the condition of multipoint grounding exists, the PLC 4 triggers an alarm device, and the specific steps are as follows:
step S51: the output contact of the AND gate outputs high level to trigger the relay K1 to act, so that the normally open contact K1-1 is closed;
step S52: the normally open contact K1-1 is closed, so that the relays KT1 and KT2 are triggered to act;
step S53: the relays KT1 and KT2 act, two delay time relays are arranged, interference caused by unstable factors caused by environmental factors is prevented, and the outlet relay K2 can be triggered only when the two relays act simultaneously; therefore, the delayed normally-open contacts KT1-1, KT1-2, KT2-1 and KT2-2 are closed in a delayed mode, the relay K2 is triggered to act, and the possibility of misoperation or operation rejection can be effectively avoided by utilizing the two groups of normally-open contacts which are connected in parallel and then connected in series.
Step S54: the relay K2 is operated, so the PLC output contacts D0.1 and D0.2 are closed, the normally open contact K2-1 is closed to form a self-holding loop, and the relay K2 is connected with the normally open contact K2-1 in series to prevent the signal from disappearing due to the return of the current of the grounding wire, so as to remind the operation and maintenance personnel that the grounding is carried out at multiple points once, but the signal is returned due to the change of the load current and other reasons.
Step S55: the PLC output contacts D0.1 and D0.2 are closed, so that the relays K4 and K5 are triggered to act;
step S56: the relays K4 and K5 act, so that normally open contacts K4-1 and K5-1 are closed, a multipoint grounding alarm signal of the audible and visual alarm 5 and the NCS system is triggered, and information of 'CT secondary circuit multipoint grounding' is popped up on the NCS display screen.
Step S6: if the multipoint earthing is not present, the PLC controller 4 does not perform other operations.
Further, in another embodiment, a reset function is further included, and step S7 is as follows:
step S71: pressing a reset button SB to trigger a relay K3 to act;
step S72: the normally closed contact K3-1 is opened, the relay K2 loop is disconnected, and the alarm signal disappears.
Due to the steps, the alarm signal can be reset after the operation maintenance personnel find the alarm signal, and after the reset button is pressed down, the normally closed contact K3-1 of the relay K3 is opened, so that the relay K2 is disconnected, and the alarm signal disappears.
Further, in another embodiment, the method further includes a dc power monitoring function, and step S8 is as follows:
step S81: when the direct current power supply disappears, the monitoring relay Z1 loses power, so the normally closed contact Z1-1 is closed;
step S82: the normally closed contact Z1-1 is closed, so that a direct current power failure alarm signal of the NCS system is triggered, and a 'direct current power failure of a CT secondary circuit multipoint grounding alarm device' message is popped up on an NCS display screen.
The invention can monitor the grounding condition of the CT secondary circuit and can also monitor the self power-on condition in real time, and once the invention loses power, the invention can immediately alarm and send out warning to operation maintenance personnel through the step S8, thereby effectively avoiding the condition that the CT secondary circuit cannot be monitored due to the power loss of the invention and greatly improving the practicability of the invention.
The above technical solutions are all understandable to those skilled in the art.
The working principle of one embodiment of the invention is as follows:
the current value of the grounding wire of the neutral point N is acquired by utilizing a high-precision pincerlike current transformer, the grounding wire current value is input into a high-precision alternating current transmitter for analog quantity conversion, the converted output quantity of the high-precision alternating current transmitter (4-20 mA) is input into an acquisition module of a PLC (programmable logic controller), and is compared with a preset current constant value (50mA) of the PLC, when the current output quantity of the transmitter is greater than the current constant value set by the PLC,
the AND gate outputs high level to trigger the relay K1 to act, and then the normally open contact K1-1 is closed. After the relay K1 acts, the time delay relays KT1 and KT2 are triggered, after set time delay and disturbance avoidance, normally open contacts KT1-1, KT1-2, KT2-1 and KT2-2 are closed, and the relay K2 is triggered to act. Two time delay time relays are arranged to prevent unstable factors caused by environmental factors, eliminate possible interference and trigger the outlet relay K2 only by two simultaneous actions. Meanwhile, the normally open contacts KT1-1 and KT1-2 of the time delay relay are firstly connected in parallel, then connected in parallel with the normally open contacts KT2-1 and KT2-2 of the time delay relay and then connected in series, and then connected in parallel with the normally closed contacts K3-1 of the relay K2 and the relay K3 and then connected in series, so that the possibility of misoperation or refusal can be effectively avoided by utilizing the two normally open contacts which are firstly connected in parallel and then connected in series. In order to prevent the signal from disappearing due to the return of the current of the grounding wire, a relay K2 and a normally open contact K2-1 are also arranged in series to form a self-holding loop so as to remind an operator that the grounding is carried out at multiple points and the signal is returned due to the change of the load current and the like.
After the relay K2 acts, the PLC output contacts D0.1 and D0.2 are closed, the relays K4 and K5 are triggered to act, the normally open contact K4-1 of the relay K4 is closed to trigger the audible and visual alarm, the normally open contact K5-1 of the relay K5 is closed to trigger the multipoint grounding alarm signal of the NCS system, and the display screen of the NCS system pops up the multipoint grounding alarm information of the CT secondary circuit. The relay Z1 is also arranged and used for monitoring the direct current 110V power supply, when the direct current power supply disappears, the relay Z1 loses power, the relay Z1 normally closed contact Z1-1 is closed to trigger a direct current power failure alarm signal of the NCS system, and a display screen of the NCS system pops up alarm information of 'the CT secondary circuit multipoint grounding alarm device disappears' of the direct current power supply.
When the operation maintainer confirms the signal, the reset button is pressed to reset the alarm signal and the acousto-optic signal of the related loop, after the reset loop is closed, the relay K3 is triggered to act, the normally closed contact K3-1 is opened, the loop of the relay K2 is disconnected, and the alarm signal disappears.
According to the description and the drawings of the present invention, those skilled in the art can easily manufacture or use the CT secondary circuit multipoint grounding on-line monitoring device and the monitoring method thereof, and can generate the positive effects described in the present invention.
Unless otherwise specified, in the present invention, if there is an orientation or positional relationship indicated by terms of "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, rather than to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, the terms describing orientation or positional relationship in the present invention are for illustrative purposes only, and should not be construed as limiting the present patent, specific meanings of the above terms can be understood by those of ordinary skill in the art in light of the specific circumstances in conjunction with the accompanying drawings.
Unless expressly stated or limited otherwise, the terms "disposed," "connected," and "connected" are used broadly and encompass, for example, being fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.
Claims (5)
1. The utility model provides a CT secondary circuit multiple spot ground connection on-line monitoring device which characterized in that: the device comprises a point grounding connecting line (1), a current transformer (2), a transmitter U1(3), a PLC (programmable logic controller) controller (4), a relay group, a resistor group and an alarm device;
the one-point grounding connecting line (1) is connected between a grounding point N of a secondary circuit of the CT and a secondary equipotential ground network M, the current transformer (2) is connected in series with the one-point grounding connecting line (1), the transmitter U1(3) is electrically connected with the secondary side of the current transformer (2), the PLC controller (4) is electrically connected with the output end of the transmitter U1(3), and the relay group is used for receiving and executing a command of the PLC controller (4);
the resistor group comprises a resistor R0 and a resistor R1;
the alarm device comprises an acousto-optic alarm (5) and an NCS system;
the relay group comprises a relay K1 and a normally open contact K1-1 thereof, a relay KT1 and time-delay normally open contacts KT1-1 and KT1-2 thereof, a relay KT2 and time-delay normally open contacts KT2-1 and KT2-2 thereof, a relay K2 and a normally open contact K2-1 thereof, a relay K3 and a normally open contact K3-1 thereof, a relay K4 and a normally open contact K4-1 thereof, a relay K5 and a normally open contact K5-1 thereof, and a monitoring relay Z1;
the PLC and gate output contact and the relay K1 are connected in series on a direct current power supply;
the relays KT1 and KT2 are connected in parallel and are called as a first parallel group; the normally open contact K1-1 of the relay K1 and the first parallel group are connected in series on a direct current power supply;
the time-delay normally-open contact KT1-1 of the relay KT1 is connected with the time-delay normally-open contact KT2-1 of the relay KT2 in parallel and is called a second parallel group, and the time-delay normally-open contact KT1-2 of the relay KT1 is connected with the time-delay normally-open contact KT2-2 of the relay KT2 in parallel and is called a third parallel group; the two ends of the third parallel group are also connected with a normally open contact K2-1 of a relay K2 in parallel, and the normally closed contacts K3-1 of the second parallel group, the third parallel group, the relay K2 and the relay K3 are sequentially connected on a direct-current power supply in series;
the relay K3, the resistor R0 and the reset button SB are sequentially connected in series on a direct-current power supply;
the PLC output contact D0.1 and the relay K4 are connected in series on a direct current power supply, and a normally open contact K4-1 of the relay K4, the audible and visual alarm (5) and the resistor R1 are sequentially connected in series on the direct current power supply;
the PLC output contact D0.2 and the relay K5 are connected in series on a direct current power supply, and the normally open contact K5-1 of the relay K5 and the multipoint grounding alarm signal of the NCS system are connected in series on the direct current power supply;
both ends of the transmitter U1(3) and the monitoring relay Z1 are connected to a direct current power supply;
and a normally closed contact Z1-1 of the monitoring relay Z1 and a direct current power failure alarm signal of the NCS system are connected in series on a direct current power supply.
2. The CT secondary circuit multipoint grounding on-line monitoring device according to claim 1, characterized in that: the current transformer (2) is a high-precision pincerlike current transformer (2).
3. The monitoring method of the CT secondary circuit multipoint earthing on-line monitoring device according to any of claims 1 to 2, characterized in that: the method comprises the following steps:
step S1: a specific current threshold value is preset in the PLC (4);
step S2: the current transformer (2) collects the current value on the grounding wire in real time;
step S3: the transmitter U1(3) converts the current value acquired by the current transformer (2) into a current value which can be identified by the PLC controller (4), and transmits the current value to the PLC controller (4);
step S4: the current value received by the PLC (4) is compared with a preset current threshold value, and whether the secondary circuit of the current transformer (2) is in multipoint grounding condition is judged according to the comparison result;
step S5: if the multipoint grounding condition exists, the PLC (4) triggers an alarm device, and the specific steps are as follows:
step S51: the output contact of the AND gate outputs high level to trigger the relay K1 to act, so that the normally open contact K1-1 is closed;
step S52: the normally open contact K1-1 is closed, so that the relays KT1 and KT2 are triggered to act;
step S53: the relay KT1 and the relay KT2 act, so that the time-delay normally-open contacts KT1-1, KT1-2, KT2-1 and KT2-2 are closed in a time-delay manner, and the relay K2 is triggered to act;
step S54: the relay K2 acts, so that the PLC output contacts D0.1 and D0.2 are closed, and the normally open contact K2-1 is closed to form a self-holding loop;
step S55: the PLC output contacts D0.1 and D0.2 are closed, so that the relays K4 and K5 are triggered to act;
step S56: the relays K4 and K5 act, so that normally open contacts K4-1 and K5-1 are closed, a multipoint grounding alarm signal of an audible and visual alarm (5) and an NCS system is triggered, and information of 'CT secondary circuit multipoint grounding' is popped up on an NCS display screen.
Step S6: if the multipoint earthing condition does not exist, the PLC controller (4) does not perform other actions.
4. The monitoring method based on the CT secondary circuit multipoint grounding online monitoring device as claimed in claim 3, characterized in that: further comprising a reset function, step S7 is as follows:
step S71: pressing a reset button SB to trigger a relay K3 to act;
step S72: the normally closed contact K3-1 is opened, the relay K2 loop is disconnected, and the alarm signal disappears.
5. The monitoring method based on the CT secondary circuit multipoint grounding online monitoring device as claimed in claim 3, characterized in that: the method also comprises a direct current power supply monitoring function, and the step S8 is as follows:
step S81: when the direct current power supply disappears, the monitoring relay Z1 loses power, so the normally closed contact Z1-1 is closed;
step S82: the normally closed contact Z1-1 is closed, so that a direct current power failure alarm signal of the NCS system is triggered, and a 'direct current power failure of a CT secondary circuit multipoint grounding alarm device' message is popped up on an NCS display screen.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020057162A1 (en) * | 1999-12-06 | 2002-05-16 | Jerome Johnson Tiemann | Current transformer and method for correcting asymmetries therein |
| CN102121958A (en) * | 2010-01-07 | 2011-07-13 | 王世祥 | Device and method for monitoring neutral point earthing of secondary winding of electric power current and voltage mutual inductor |
| CN103983895A (en) * | 2014-04-08 | 2014-08-13 | 广西电网公司电力科学研究院 | PT secondary circuit online N-line multipoint ground fault detection method and device |
| CN104407265A (en) * | 2014-11-14 | 2015-03-11 | 深圳供电局有限公司 | Method and device for monitoring line defects in bus differential protective current analog quantity of transformer substation |
| CN110954845A (en) * | 2019-12-19 | 2020-04-03 | 深圳供电局有限公司 | CT secondary circuit multipoint earth fault on-line monitoring system and method |
| CN111060846A (en) * | 2019-12-19 | 2020-04-24 | 深圳供电局有限公司 | CT secondary circuit fault on-line monitoring method |
-
2020
- 2020-06-15 CN CN202010543214.9A patent/CN111694306B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020057162A1 (en) * | 1999-12-06 | 2002-05-16 | Jerome Johnson Tiemann | Current transformer and method for correcting asymmetries therein |
| CN102121958A (en) * | 2010-01-07 | 2011-07-13 | 王世祥 | Device and method for monitoring neutral point earthing of secondary winding of electric power current and voltage mutual inductor |
| CN103983895A (en) * | 2014-04-08 | 2014-08-13 | 广西电网公司电力科学研究院 | PT secondary circuit online N-line multipoint ground fault detection method and device |
| CN104407265A (en) * | 2014-11-14 | 2015-03-11 | 深圳供电局有限公司 | Method and device for monitoring line defects in bus differential protective current analog quantity of transformer substation |
| CN110954845A (en) * | 2019-12-19 | 2020-04-03 | 深圳供电局有限公司 | CT secondary circuit multipoint earth fault on-line monitoring system and method |
| CN111060846A (en) * | 2019-12-19 | 2020-04-24 | 深圳供电局有限公司 | CT secondary circuit fault on-line monitoring method |
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