CN106158335A - A kind of three-phase resonance-eleminating type voltage inductor - Google Patents
A kind of three-phase resonance-eleminating type voltage inductor Download PDFInfo
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- CN106158335A CN106158335A CN201610783100.5A CN201610783100A CN106158335A CN 106158335 A CN106158335 A CN 106158335A CN 201610783100 A CN201610783100 A CN 201610783100A CN 106158335 A CN106158335 A CN 106158335A
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- 238000004804 winding Methods 0.000 claims abstract description 91
- 230000007935 neutral effect Effects 0.000 claims abstract description 29
- 238000009413 insulation Methods 0.000 claims abstract description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 12
- 230000008030 elimination Effects 0.000 claims description 21
- 238000003379 elimination reaction Methods 0.000 claims description 21
- 230000016507 interphase Effects 0.000 claims description 11
- 239000003822 epoxy resin Substances 0.000 claims description 3
- 229920000647 polyepoxide Polymers 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims 2
- 238000010125 resin casting Methods 0.000 claims 1
- 230000005350 ferromagnetic resonance Effects 0.000 abstract description 11
- 238000005259 measurement Methods 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 10
- 239000003990 capacitor Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
- 230000005284 excitation Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000013016 damping Methods 0.000 description 3
- 230000001939 inductive effect Effects 0.000 description 3
- 238000005266 casting Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 230000005291 magnetic effect Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/38—Instruments transformers for polyphase ac
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/2823—Wires
- H01F27/2828—Construction of conductive connections, of leads
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformers For Measuring Instruments (AREA)
Abstract
The invention provides a kind of three-phase resonance-eleminating type voltage inductor, including a winding, Secondary Winding, iron core and insulation, wherein, a described winding A, B, C leading-out terminal phase line corresponding with high-voltage fence respectively connects, the star connection neutral point of winding A and winding C is connected with the head end of a winding B, the end ground connection of winding B, described Secondary Winding is divided into three group windings, wherein, the indirect kilowatt-hour meter wh of outlet terminal a1 Yu b1 of secondary measurement winding, the indirect kilowatt-hour meter wh of outlet terminal b1 Yu c1, the outlet terminal a2 of double measurement winding, b2, c2, n connects voltmeter V between phase line, residue winding is open delta wiring, conventional symmetrical neutral ground has been broken in this invention, the for once end ground connection of winding B；And only B N winding can provide the passage of zero-sequence current, destroy the condition that zero-sequence current produces, solve the problem of ferromagnetic resonance in isolated neutral system simply and effectively.
Description
Technical Field
The invention relates to the technical field of voltage transformers, in particular to a three-phase harmonic elimination type voltage transformer.
Background
The insulation systems of 10-35kv power grids in China are neutral point insulation systems. In a power system with neutral point to ground insulation, in order to monitor the insulation of the line, as shown in fig. 1, three star-connected grounded voltage transformers are used, in which the neutral point is directly grounded, as shown in fig. 1: cA、CB、CCThree phase to ground equivalent capacitances; A. b, C three-phase inductance LA、LB、LCCorresponding reactance is XmA、XmB、XmCWhen the neutral point non-effective grounding system is in normal operation, XmA≈XmB≈XmC，CA≈CB≈CCThe neutral point voltage is zero. When any one phase of bus has single complete grounding accident, the voltage of the fault phase to the ground is 0V, and the phase voltage of the non-fault phase rises to the line voltage, namely, the voltage is increasedThe 3-block voltmeter measuring each phase voltage by the secondary winding of the voltage transformer can conveniently monitor which phase is insulated and has a problem. However, the bus line to ground capacitance CA、CB、CCThe capacitor and the primary winding of the voltage transformer form a parallel circuit, and the transformer is a typical nonlinear ferromagnetic element, and when some excitation occurs, such as closing of an air drop bus or a short circuit, generation and disappearance of a single-phase arc grounding, sudden rise of voltage and the like, the voltage of a certain two-phase voltage transformer is likely to change. And since PT is Y0/Y0The wiring is neutral point symmetrical grounding, the grounding capacitor is also neutral point symmetrical grounding, two-phase voltage in three phases changes, PT neutral point displacement generates zero-sequence current and zero-sequence voltage, and the small zero-sequence current generates enough zero-sequence magnetic flux in the non-fault phase voltage transformer to saturate the iron core, so that the nonlinear iron core is saturatedInductive reactance X of magnetic elementLReduce, at a certain moment, when the inductive reactance in the line is equal to the capacitive reactance (X)L＝XC) Ferromagnetic resonance will occur.
In order to monitor the system for insulation grounding, grounding voltage transformers are commonly used in the system, and currently, a mode of connecting three single-phase voltage transformers into a three-phase group is mostly adopted. The voltage transformers are all electromagnetic type, are nonlinear inductance elements, are connected in parallel with a power grid wire to ground capacitor to form a ferromagnetic resonance loop, generate resonance under a certain excitation condition, and generate overvoltage and overcurrent. Operation experience shows that voltage transformer burnout and power grid power failure accidents caused by ferromagnetic resonance are common.
For a long time, a power system has conducted many experimental studies on this, and a series of harmonic elimination measures have been taken and put into practice. The main resonance elimination measures are: (1) the excitation characteristic of the voltage transformer is improved: the most fundamental is to select a voltage transformer with good excitation volt-ampere characteristic, and the iron core of the voltage transformer is not enough to enter a deep saturation region under a common overvoltage level, so that the voltage transformer and line parameters do not form matching parameters for generating resonance. (2) The number of voltage transformers connected in parallel in the same network is reduced: in the same power grid, the more the number of voltage transformers which are operated in parallel, the worse the total voltage-current characteristic becomes, the smaller the total equivalent inductive reactance becomes, and if the capacitance current in the power grid is larger, ferromagnetic resonance is easy to occur. The number of voltage transformers in the same system should be reduced as much as possible. (3) Every phase of a 10kV bus is provided with a capacitor: when X in the systemC/XLWhen the frequency is less than or equal to 0.01, ferromagnetic resonance is not easy to occur. Therefore, a capacitor bank with a grounded neutral point can be additionally arranged in a small substation below 10kV or a reliable cable is selected to replace a section of outgoing line overhead bus. For the condition that a large substation is connected with a plurality of voltage transformers, the method of additionally arranging the capacitor is not suitable for being adopted due to the fact that the capacitance which needs to be additionally arranged is large. (4) A harmonic eliminator or a series resistor is arranged at the neutral point of a voltage transformer in the system and is grounded: when a ground fault occurs, the resonance eliminator is conducted due to the higher voltage appearing on the resonance eliminatorTherefore, the voltage transformer can play the roles of energy consumption, damping and current suppression, and the voltage on the voltage transformer is reduced, so that the volt-ampere characteristic of the voltage transformer is improved. But the resistance should be chosen to be large. However, when the resistance is too large, the open-delta voltage is reduced when the single phase is grounded, which has a certain influence on the correct operation of the protection. Therefore, a reasonable resistor is selected, a nonlinear resistor is suitable, the resistance value is large in normal conditions, and the resistance value is reduced under the action of high voltage when a fault occurs, so that the functions of energy consumption, damping and the like can be achieved, and the reliability of the protection function of the opening triangle is not influenced. This approach is often used in systems of 10kV and below. (5) The three open corners of the voltage transformer are provided with a resonance elimination device or a resistor: the resonance eliminating device or the resistor is arranged at the three opening corners of the voltage transformer, so that the effects of damping, resonance elimination and resonance inhibition can be achieved, the effect of limiting the current in the voltage transformer can be achieved, and the current of each phase of the voltage transformer is reduced, so that the volt-ampere characteristic is improved. (6) The high-voltage side neutral point is connected with a single-phase voltage transformer in series: a single-phase voltage transformer (namely a zero-sequence voltage transformer) is connected in series with a neutral point on the high-voltage side of the voltage transformer.
The measures described above each have a certain effect in practice on suppressing resonance. However, the resonance elimination measures used in neutral point insulation systems are mostly passive resonance elimination, i.e. the resonance elimination device only functions after the occurrence of a resonance. If the resonance is not effectively eliminated once the resonance-eliminating measures have failed, the harm remains.
Disclosure of Invention
The application provides a three-phase harmonic elimination formula voltage transformer to solve the technical problem of ferromagnetic resonance among the neutral point insulating system.
In order to solve the technical problems, the application adopts the following technical scheme:
a three-phase harmonic elimination type voltage transformer comprises a primary winding, a secondary winding, an iron core and insulation, wherein an outlet end of the primary winding A, B, C is connected with a corresponding phase line of a high-voltage power grid respectively, star junction neutral points of the primary winding A and the primary winding C are connected with a head end of the primary winding B, the tail end of the primary winding B is directly grounded, the secondary winding is divided into three groups of windings, an electric meter wh is connected between outlet terminals a1 and B1 of the secondary metering winding, an electric meter wh is connected between outlet terminals B1 and C1, outlet terminals a2, B2, C2 and n of the secondary metering winding are connected with a voltmeter V between the phase lines, the rest winding is in open delta connection, and the outlet terminals are da and dn.
The invention cancels the traditional method that 3 grounding voltage transformers are connected in star shape, wherein the neutral point is directly grounded, but only one end N of the winding B is grounded, and only the B-N winding can provide a channel of zero sequence current, thereby destroying the condition of generating the zero sequence current.
Further, the winding AB and the winding BC work at the online voltage, the winding B0 works at the phase voltage, and the phase voltage is:wherein,is the voltage of the inter-phase B0 phase,is the voltage of the inter-phase a0 phase,is the line voltage between the line voltage AB,is the voltage of the inter-phase C0 phase,is the line voltage between BC.
Furthermore, the three-phase harmonic elimination type voltage transformer is formed by casting epoxy resin, and belongs to maintenance-free products.
Compared with the prior art, the technical scheme that this application provided, the technological effect or advantage that have are:
1) the invention cancels the wiring form of the traditional mutual inductor with the symmetrical neutral point grounding, only the B-N winding can provide a channel of zero-sequence current, the condition of frequency division resonance is destroyed, and the frequency division resonance and other resonances are eliminated, therefore, the resonance can not be caused by any operation of the system.
2) In which single-phase earthing occurs, with relative earth inductance XLThe size of the transformer core cannot be reduced, the iron core cannot be magnetized and saturated or resonate, and the voltage transformer cannot be damaged. The GB20840.3-2013 standard is implemented, the service condition of a 10kV insulation system is met, and resonance can not occur under various disturbance factors in system operation. The self-recovery capability to the pollution flashover grounding fault is unique.
3) Tests and practices prove that the voltage transformer is irrelevant to the size of the system grounding capacitor and can be used for grounding the grounding capacitor
The flow is arbitrarily compensated.
In conclusion, the three-phase harmonic elimination type voltage transformer can meet the normal use function, can eliminate the adverse effect of the traditional voltage transformer on the system, and creates a powerful supporting point for the safe and reliable operation of the power system.
Drawings
FIG. 1 is an equivalent circuit diagram of a conventional electromagnetic voltage transformer;
FIG. 2 is a primary winding wiring schematic of the present invention;
FIG. 3 is a schematic diagram of the secondary metering winding wiring of the present invention;
FIG. 4 is a schematic diagram of the secondary measurement winding wiring of the present invention;
FIG. 5 is a schematic diagram of the residual winding wiring of the present invention;
FIG. 6 is a wiring circuit diagram of the present invention;
FIG. 7 is a voltage vector diagram of the present invention;
FIG. 8 is an equivalent vector diagram of the three-phase voltage of the present invention.
Detailed Description
The embodiment of the application provides a three-phase harmonic elimination type voltage transformer to solve the technical problem of ferromagnetic resonance in a neutral point insulation system.
In order to better understand the technical solutions, the technical solutions will be described in detail below with reference to the drawings and specific embodiments.
Example 1:
a three-phase harmonic elimination type voltage transformer comprises a primary winding, a secondary winding, an iron core and an insulator, wherein outlet ends of the primary winding A, B, C are respectively connected with corresponding phase lines of a high-voltage power grid, as shown in fig. 2, star junction neutral points of a primary winding A and a primary winding C are connected with the head end of a primary winding B, the tail end of the primary winding B is directly grounded, the secondary winding is divided into three groups of windings, as shown in fig. 3, a watt-hour meter wh is connected between outlet terminals a1 and B1 of the secondary metering winding, a watt-hour meter wh is connected between outlet terminals B1 and C1, as shown in fig. 4, a voltmeter V is connected between the outlet terminals a2, B2, C2 and n of the secondary metering winding, as shown in fig. 5, the rest windings are in open delta connection mode, and the outlet terminals are da and dn. Fig. 6 is a wiring circuit diagram of the present invention.
The invention cancels the traditional method that 3 grounding voltage transformers are connected in star shape, wherein the neutral point is directly grounded, but only one end N of the winding B is grounded, only the B-N winding can provide a channel of zero sequence current, thereby destroying the condition of generating the zero sequence current, and tests and practices prove that the special wiring design successfully solves the problem of ferromagnetic resonance in a neutral point insulation system.
The AB winding and the CB winding are connected with the phase-to-phase voltage (namely the line voltage) for measurement and measurement. The impedance of the voltage transformer is in parallel connection with the system impedance, the winding impedance is greater than the system impedance, the initial saturation voltage of the winding volt-ampere characteristic is greater than 2 times of the line voltage, the iron core of the voltage transformer cannot enter a deep saturation region under the general overvoltage level, and the overload capacity is strong. In addition, when the A phase or the C phase generates single-phase grounding, the inductive reactance X of the grounding windingLIt is not reduced and the core is not saturated or causes resonance.
The three-phase harmonic elimination type voltage transformer adopts the three single-phase voltage transformers to be combined into a whole through special wiring (namely, the method of directly grounding a neutral point is cancelled, and only one end N end of a winding B is grounded) on the whole structure so as to eliminate ferromagnetic resonance. The rectangular integral iron core is adopted by the inner iron core of each single-phase voltage transformer, so that the manufacturing is convenient, the working time is saved, the exciting current is reduced, the no-load loss of the exciting current is reduced, the product quality is improved, and the error is reduced; the primary winding is provided with an inner shielding layer and an outer shielding layer, so that the partial discharge level is improved, and the voltage gradient is improved; the winding aspect adopts the full-automatic winding machine equipment controlled by the CPU, so that the work efficiency and the product quality can be improved.
Further, fig. 7 shows a voltage vector diagram of the present invention, in which the winding AB and the winding BC operate at an online voltage, and the winding B0 operates at a phase voltage, where the phase voltage is:wherein,is the voltage of the inter-phase B0 phase,is the voltage of the inter-phase a0 phase,is the line voltage between the line voltage AB,is the voltage of the inter-phase C0 phase,is the line voltage between BC.
Fig. 8 shows an equivalent vector diagram of three-phase voltages of the present invention, which is the same as the conventional voltage-variable wiring set for protection and insulation monitoring.
Furthermore, the three-phase harmonic elimination type voltage transformer is formed by casting epoxy resin, and belongs to maintenance-free products.
In the above embodiments of the present application, by providing a three-phase harmonic elimination type voltage transformer, which includes a primary winding, a secondary winding, an iron core and an insulator, wherein the outlet ends of the primary winding A, B, C are respectively connected with the corresponding phase lines of a high voltage grid, star junction neutral points of the primary winding a and the primary winding C are connected with the head end of the primary winding B, the tail end of the primary winding B is grounded, the secondary winding is divided into three groups of windings, wherein a watt meter wh is connected between the outlet terminals a1 and B1 of the secondary metering winding, a watt meter wh is connected between the outlet terminals B1 and C1, the outlet terminals a2, B2, C2 and N of the secondary metering winding are connected with an inter-phase voltmeter V, and the remaining windings are open delta connections, the invention cancels the traditional symmetrical neutral point grounding, only the B-N winding can provide a zero-sequence current channel, and breaks the condition of generating the zero-sequence current, the problem of ferromagnetic resonance in a neutral point insulation system is simply and effectively solved.
It should be noted that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make variations, modifications, additions or substitutions within the spirit and scope of the present invention.
Claims (3)
1. A three-phase harmonic elimination type voltage transformer comprises a primary winding, a secondary winding, an iron core and insulation, wherein outlet ends of the primary winding A, B, C are respectively connected with corresponding phase lines of a high-voltage power grid, and the three-phase harmonic elimination type voltage transformer is characterized in that star junction neutral points of the primary winding A and the primary winding C are connected with the head end of the primary winding B, the tail end of the primary winding B is grounded, the secondary winding is divided into three groups of windings, wherein an outlet terminal a1 and a B1 of the secondary metering winding are connected with an electricity meter wh, an outlet terminal B1 and a C1 are connected with the electricity meter wh, outlet terminals a2, B2, C2 and n of the secondary metering winding are connected with an inter-phase voltmeter V, the rest of the outlet windings are in open delta connection, and the outlet terminals are da.
2. The three-phase harmonic elimination voltage transformer of claim 1 wherein windings AB and BC operate at on-line voltage and windings B0 operate at phase voltages: wherein,is the voltage of the inter-phase B0 phase,is the voltage of the inter-phase a0 phase,is the line voltage between the line voltage AB,is the voltage of the inter-phase C0 phase,is the line voltage between BC.
3. The three-phase resonance-eliminating voltage transformer according to claim 1, wherein the three-phase resonance-eliminating voltage transformer is molded by epoxy resin casting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610783100.5A CN106158335A (en) | 2016-08-31 | 2016-08-31 | A kind of three-phase resonance-eleminating type voltage inductor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610783100.5A CN106158335A (en) | 2016-08-31 | 2016-08-31 | A kind of three-phase resonance-eleminating type voltage inductor |
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| CN106158335A true CN106158335A (en) | 2016-11-23 |
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| CN201610783100.5A Pending CN106158335A (en) | 2016-08-31 | 2016-08-31 | A kind of three-phase resonance-eleminating type voltage inductor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106783098A (en) * | 2017-03-02 | 2017-05-31 | 国网甘肃省电力公司兰州供电公司 | Three-phase electricity magnetic-type resonance free voltage transformer wiring group |
| CN108630420A (en) * | 2018-07-16 | 2018-10-09 | 国网四川省电力公司电力科学研究院 | A kind of three element combination transformer of three-phase |
| CN112491063A (en) * | 2020-11-23 | 2021-03-12 | 国网北京市电力公司 | Method, system and device for inhibiting low-frequency nonlinear oscillation |
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|---|---|---|---|---|
| JP2001305176A (en) * | 2000-04-25 | 2001-10-31 | Nippon Kouatsu Electric Co | Grounding point standardizing method for power distribution line |
| CN201438412U (en) * | 2009-03-13 | 2010-04-14 | 上海大一互电力电器有限公司 | Zero sequence voltage transformer for neutral point |
| CN201489988U (en) * | 2009-04-14 | 2010-05-26 | 萧楠 | Non-resonance three-phase integrated voltage mutual inductor |
| CN203942275U (en) * | 2014-06-27 | 2014-11-12 | 重庆大学 | A kind of 35kV isolated neutral power distribution network ferro resonance restraining device |
| CN206040418U (en) * | 2016-08-31 | 2017-03-22 | 天水长开互感器制造有限公司 | Three -phase harmonic elimination formula voltage transformer |
-
2016
- 2016-08-31 CN CN201610783100.5A patent/CN106158335A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001305176A (en) * | 2000-04-25 | 2001-10-31 | Nippon Kouatsu Electric Co | Grounding point standardizing method for power distribution line |
| CN201438412U (en) * | 2009-03-13 | 2010-04-14 | 上海大一互电力电器有限公司 | Zero sequence voltage transformer for neutral point |
| CN201489988U (en) * | 2009-04-14 | 2010-05-26 | 萧楠 | Non-resonance three-phase integrated voltage mutual inductor |
| CN203942275U (en) * | 2014-06-27 | 2014-11-12 | 重庆大学 | A kind of 35kV isolated neutral power distribution network ferro resonance restraining device |
| CN206040418U (en) * | 2016-08-31 | 2017-03-22 | 天水长开互感器制造有限公司 | Three -phase harmonic elimination formula voltage transformer |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106783098A (en) * | 2017-03-02 | 2017-05-31 | 国网甘肃省电力公司兰州供电公司 | Three-phase electricity magnetic-type resonance free voltage transformer wiring group |
| CN108630420A (en) * | 2018-07-16 | 2018-10-09 | 国网四川省电力公司电力科学研究院 | A kind of three element combination transformer of three-phase |
| CN112491063A (en) * | 2020-11-23 | 2021-03-12 | 国网北京市电力公司 | Method, system and device for inhibiting low-frequency nonlinear oscillation |
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