CN114384297A - Magnetic balance alternating current sensor - Google Patents
Magnetic balance alternating current sensor Download PDFInfo
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- CN114384297A CN114384297A CN202111669931.7A CN202111669931A CN114384297A CN 114384297 A CN114384297 A CN 114384297A CN 202111669931 A CN202111669931 A CN 202111669931A CN 114384297 A CN114384297 A CN 114384297A
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- phase
- sequence current
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- sequence
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
Abstract
A magnetic balance alternating current sensor is applied to measurement and protection of a power distribution network of a three-phase circuit and comprises a flame-retardant shell, a magnetic balance sensor and a magnetic balance control circuit, wherein the flame-retardant shell is used for protecting the internal structure of the sensor; three circular preformed holes are arranged in the flame-retardant shell in an inserting mode and used for placing a three-phase circuit; the three phase sequence current coils are attached to the edges of the circular preformed hole and used for measuring the phase sequence current of the three-phase circuit; the three zero-sequence current coils are attached to the edge of the circular reserved hole, and each zero-sequence current coil is adjacent to each phase-sequence current coil and used for measuring the zero-sequence current of the three-phase circuit; and the non-inductive resistors are arranged in the flame-retardant shell, and the phase-sequence current coil and the zero-sequence current coil are arranged outside. Has the advantages that: the functions are various, the installation and the use are simple and convenient, the energy consumption is reduced in the operation, and the equipment maintenance is not needed; the sampling device has the advantages of light weight, small volume and wide measurement range, and overcomes the defects of narrow frequency band, slow response and the like of the traditional sampling device.
Description
Technical Field
The invention relates to a magnetic balance alternating current sensor, in particular to a magnetic balance alternating current sensor with a measurement protection function shared for a power distribution network.
Background
In order to meet the requirement of fine management of the line loss of the national power grid and realize the measurement of the line loss of the branch line of the power distribution network, a new requirement needs to be provided for a primary equipment current transformer so as to meet the requirement of measurement precision. With the rapid development of electronic technology, a microcomputer type relay protection device gradually takes a leading position, and in relay protection and measurement, energy flow and information flow of a control part are separated, so that a monitoring device does not need a transformer with high power output for sampling.
When the current sensor works at the temperature of between 40 ℃ below zero and 70 ℃ outdoors, the current sensor has a large error range, weak anti-interference capability, poor product ratio and phase difference which are easily interfered by external electromagnetic fields.
Disclosure of Invention
Due to the rapid development of the power industry and the more complex power grid conditions, the intelligent current sensor for improving the power factor and the quality of the power grid is widely applied. Because of the particularity of the pole-mounted switch and the ring main unit for the power distribution network, the invention develops a magnetic balance alternating current sensor with shared measurement and protection functions for the power distribution network, provides current acquisition signals for a power distribution terminal FTU/DTU, and is a magnetic balance phase zero sequence integrated bus current sensor with shared measurement and protection functions of current sampling, measurement, zero sequence and protection functions, which is specially designed and specially designed, the invention provides a magnetic balance alternating current sensor which is applied to the measurement and protection of the power distribution network of a three-phase circuit and is characterized by comprising,
a flame retardant housing for protecting the sensor internal structure;
three circular preformed holes are arranged in the flame-retardant shell in an inserting mode and used for placing a three-phase circuit;
the three phase sequence current coils are attached to the edge of the circular preformed hole, each phase sequence current coil comprises a first iron core and corresponds to one phase of the three-phase circuit, and the phase sequence current coils are used for measuring the phase sequence current of the three-phase circuit;
the three zero-sequence current coils are attached to the edge of the circular preformed hole, each zero-sequence current coil is adjacent to each phase-sequence current coil, each zero-sequence current coil comprises a second iron core and corresponds to one phase of the three-phase circuit, and the zero-sequence current coils are used for measuring the zero-sequence current of the three-phase circuit;
and the non-inductive resistors are arranged in the flame-retardant shell, and the phase-sequence current coil and the zero-sequence current coil are arranged outside.
Preferably, epoxy resin is filled between the flame-retardant shell and the circular reserved hole.
Preferably, the first iron core is formed by arranging a silicon steel sheet iron core and an amorphous iron core in a mixed manner.
Preferably, the second iron core is an amorphous iron core and is formed by a coil with high ampere turns.
Preferably, the three-phase circuit is coupled to each of the phase-sequence current coils, each of the phase-sequence current coils is connected in parallel to the non-inductive resistor, and outputs a first voltage signal through the non-inductive resistor, where the first voltage signal is a phase-sequence voltage and is generated when the phase sequence in the circuit is asymmetric.
Preferably, the three-phase circuit is coupled with the zero-sequence current coil, three phase-sequence current coils are connected in parallel and are connected in parallel with the non-inductive resistor, a second voltage signal is output through the non-inductive resistor, and the second voltage signal is zero-sequence voltage and is generated when the circuit is grounded and short-circuited.
Preferably, the phase-sequence current coil and the zero-sequence current coil are connected to the non-inductive resistor through a five-core shielding twisted pair.
Preferably, the zero sequence signal output generated by the zero sequence current coil is synthesized according to the zero sequence currents of three phases in the three-phase circuit.
Preferably, the first iron core and the second iron core are low-energy-consumption small iron cores, a primary winding is arranged outside the first iron core and the second iron core, a secondary winding is further arranged outside the first iron core and the second iron core, the non-inductive resistor is arranged on the secondary winding, a voltage drop is generated on the non-inductive resistor by a secondary current generated by the secondary winding, and the amplitude of the voltage drop is in direct proportion to a primary current of the primary winding and has the same phase.
Has the advantages that: the functions are various, the installation and the use are simple and convenient, the energy consumption is reduced in the operation, and the equipment maintenance is not needed; the weight is light, the volume is small, the installation space is saved, the field wiring is reduced, the structure is simple, and the performance is excellent; the measuring range is wide, and the defects of narrow frequency band, slow response and the like of the traditional electromagnetic sampling device are overcome; the small voltage signal sampling fundamentally eliminates major fault hidden dangers in the operation of the power system, and ensures the safety of personnel and equipment to the greatest extent.
Drawings
FIG. 1a is a front view of a current sensor according to a preferred embodiment of the present invention;
FIG. 1b is a side view of a current sensor according to a preferred embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a current sensor according to a preferred embodiment of the present invention;
FIG. 3 is a diagram of a small iron core coil of a current sensor according to a preferred embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments 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.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
The invention provides a magnetic balance alternating current sensor, which is applied to the measurement and protection of a power distribution network of a three-phase circuit, and is characterized in that as shown in figure 1a, the magnetic balance alternating current sensor comprises,
a flame-retardant housing 1 for protecting the internal structure of the sensor;
three circular preformed holes 2 are arranged in the flame-retardant shell 1 in an inserting mode and used for placing a three-phase circuit;
the three phase sequence current coils 3 are attached to the edge of the circular preformed hole 2, each phase sequence current coil 3 comprises a first iron core and corresponds to one phase of the three-phase circuit, and the phase sequence current coils 3 are used for measuring the phase sequence current of the three-phase circuit;
the three zero-sequence current coils 4 are attached to the edge of the circular preformed hole 2, each zero-sequence current coil 4 is adjacent to each phase-sequence current coil 3, each zero-sequence current coil 4 comprises a second iron core and corresponds to one phase of the three-phase circuit, and each zero-sequence current coil 4 is used for measuring the zero-sequence current of the three-phase circuit;
and the non-inductive resistors 5 are arranged in the flame-retardant shell 1 and outside the phase-sequence current coil 3 and the zero-sequence current coil 4.
Specifically, in the embodiment, the flame-retardant shell 1 is made of a flame-retardant material, so that the situation that a high temperature harms the sensor when a circuit fails is avoided, the circular preformed hole 2 is used for the three-phase circuit to pass through, and the sensor is placed on the inner side of the edge of the preformed hole, so that the real-time state of the three-phase circuit can be monitored;
the precision of the non-inductive resistor 5 is five parts per million, the temperature drift coefficient is small, the error range of the product is unchanged when the non-inductive resistor works at the temperature of between 40 ℃ below zero and 70 ℃ below zero, and the anti-jamming capability is strong.
In the preferred embodiment of the present invention, as shown in fig. 1b, epoxy resin 9 is filled between the flame retardant housing 1 and the circular preformed hole 2.
Specifically, in the present embodiment, the epoxy resin 9 has excellent physical mechanical and electrical insulating properties, and is suitable for filling between the flame-retardant housing 1 and the circular prepared hole 2 as an easy injection molding material.
In the preferred embodiment of the present invention, the first iron core is formed by arranging the silicon steel sheet iron core 7 and the amorphous iron core 6 in a mixed manner.
Specifically, in this embodiment, the phase-sequence current coil 3 is internally combined with the phase-sequence silicon-steel sheet iron core 7 and the phase-sequence amorphous iron core 6, so that the sharing of the measurement protection function is ensured, and meanwhile, the magnetic balance of the phase-sequence circuit is ensured due to the consistency of the phase-sequence silicon-steel sheet iron core 7 and the phase-sequence amorphous iron core 6.
In the preferred embodiment of the present invention, the second iron core is an amorphous iron core 6 and is formed by a coil with a high ampere-turn number.
Specifically, in this embodiment, the zero-sequence current coil 4 employs the amorphous iron core 6 for zero sequence and the scheme of high ampere-turns to ensure the common use of the measurement protection function, and meanwhile, the consistency of the amorphous iron core 6 for zero sequence and the metal film non-inductive resistor 5 with five ten-thousandth precision ensure the magnetic balance of the zero-sequence circuit by using the current synthesis principle.
In a preferred embodiment of the present invention, as shown in fig. 2, a three-phase circuit is coupled to each phase-sequence current coil 3, each phase-sequence current coil 3 is connected to an inductionless resistor 5 in parallel, and a first voltage signal is output through the inductionless resistor 5, where the first voltage signal is a phase-sequence voltage and is generated when the phase sequence in the circuit is asymmetric.
Specifically, in this embodiment, when the phase sequence in the circuit is asymmetric, a phase sequence voltage is generated in a different phase, the automatic protection of the circuit can be realized by using the phase sequence voltage as a control variable, and when the phase sequence voltage occurs, a response is made in time.
In the preferred embodiment of the invention, a three-phase circuit is coupled with the zero-sequence current coils 4, the three zero-sequence current coils 4 are connected in parallel and are connected in parallel with a non-inductive resistor 5, a second voltage signal is output through the non-inductive resistor 5, and the second voltage signal is zero-sequence voltage and is generated when the circuit is grounded and short-circuited.
Specifically, in this embodiment, when a ground short circuit occurs, a large zero-sequence voltage occurs, and the zero-sequence voltage is used as a control variable to protect the circuit from the ground short circuit, and the occurrence of the zero-sequence voltage proves that a ground end circuit occurs, so that a worker can timely handle the ground end circuit. Meanwhile, the output signal is more stable and reliable, and the anti-interference capability is stronger.
In the preferred embodiment of the present invention, the phase-sequence current coil 3 and the zero-sequence current coil 4 are connected to the non-inductive resistor 5 through a five-core shielded twisted pair 8.
Specifically, in this embodiment, the five-core shielded twisted pair 8 can prevent the product ratio difference and the phase difference from being interfered by an external electromagnetic field.
In a preferred embodiment of the invention, the zero sequence signal output generated by the zero sequence current coil 4 is synthesized from the zero sequence currents of the three phases in the three-phase circuit.
Specifically, in the embodiment, in a system in which the neutral point is not directly grounded, that is, a system grounded through a high-impedance grounding system or a system grounded through an arc suppression coil, when single-phase grounding occurs, zero-sequence voltage is also generated, and the zero-sequence current at this time is a composite of zero-sequence currents of three phases.
In a preferred embodiment of the present invention, as shown in fig. 3, the first iron core and the second iron core are low-energy and small-power iron cores, a primary winding is disposed outside the first iron core and the second iron core, a secondary winding is further disposed outside the first iron core and the second iron core, a non-inductive resistor 5 is disposed on the secondary winding, a voltage drop Us is generated on the non-inductive resistor 5 by a secondary current generated by the secondary winding, and the magnitude of the voltage drop is proportional to the primary current of the primary winding and has the same phase.
Specifically, in the present embodiment, the small core coil type low power current sensor includes a primary winding small core and a secondary winding with extremely low loss. The secondary winding is connected to an integrated component, so that its secondary output is a voltage signal. The secondary current produces a voltage drop on the integrated component whose magnitude is proportional to the primary current and is in phase, and the smaller the secondary power required by the internal losses and load of the sensor, the wider the measurement range and the higher the accuracy.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (9)
1. A magnetic balance alternating current sensor is applied to the measurement and protection of a power distribution network of a three-phase circuit and is characterized by comprising,
a flame retardant housing for protecting the sensor internal structure;
three circular preformed holes are arranged in the flame-retardant shell in an inserting mode and used for placing the three-phase circuit;
the three phase sequence current coils are attached to the edge of the circular preformed hole, each phase sequence current coil comprises a first iron core and corresponds to one phase of the three-phase circuit, and the phase sequence current coils are used for measuring the phase sequence current of the three-phase circuit;
the three zero-sequence current coils are attached to the edge of the circular preformed hole, each zero-sequence current coil is adjacent to each phase-sequence current coil, each zero-sequence current coil comprises a second iron core and corresponds to one phase of the three-phase circuit, and the zero-sequence current coils are used for measuring the zero-sequence current of the three-phase circuit;
and the non-inductive resistors are arranged in the flame-retardant shell, and the phase-sequence current coil and the zero-sequence current coil are arranged outside.
2. A magnetically balanced alternating current sensor according to claim 1 wherein epoxy is filled between the flame retardant casing and the circular preformed hole.
3. The magnetically balanced ac current transducer according to claim 1, wherein the first core is formed by a hybrid arrangement of silicon steel core and amorphous core.
4. A magnetically balanced alternating current sensor according to claim 1 wherein the second core is amorphous and is formed using a high ampere-turn coil.
5. A magnetically balanced ac current sensor according to claim 1 wherein said three phase circuit is coupled to each of said phase sequence current coils, each of said phase sequence current coils being connected in parallel to said non-inductive resistor, respectively, and outputting a first voltage signal through said non-inductive resistor, said first voltage signal being a phase sequence voltage generated when the phase sequence in said circuit is asymmetrical.
6. A magnetically balanced ac current sensor according to claim 1 wherein said three phase circuit couples said zero sequence current coils, three of said zero sequence current coils being connected in parallel with each other and in common with one of said non-inductive resistors, and a second voltage signal being output through said non-inductive resistors, said second voltage signal being zero sequence voltage generated when said circuit is shorted to ground.
7. A magnetically balanced alternating current sensor according to claim 1 wherein the phase-sequence current coil and the zero-sequence current coil are connected to the non-inductive resistor by a five-core shielded twisted pair.
8. A magnetically balanced alternating current sensor according to claim 6 wherein the zero sequence signal output from the zero sequence current coil is synthesized from the zero sequence currents of the three phases in a three phase circuit.
9. A magnetically balanced AC current transducer according to claim 5, wherein said first core and said second core are low energy consuming and small cores, a primary winding is disposed outside said first core and said second core, a secondary winding is disposed outside said first core and said second core, said non-inductive resistor is disposed on said secondary winding, a secondary current generated by said secondary winding generates a voltage drop on said non-inductive resistor, and the magnitude of said voltage drop is proportional to the primary current of said primary winding and is in phase with said primary current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111669931.7A CN114384297A (en) | 2021-12-30 | 2021-12-30 | Magnetic balance alternating current sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111669931.7A CN114384297A (en) | 2021-12-30 | 2021-12-30 | Magnetic balance alternating current sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114384297A true CN114384297A (en) | 2022-04-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111669931.7A Pending CN114384297A (en) | 2021-12-30 | 2021-12-30 | Magnetic balance alternating current sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114384297A (en) |
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2021
- 2021-12-30 CN CN202111669931.7A patent/CN114384297A/en active Pending
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