CN104779602A - Flexible control method of zero-sequence voltage of resonant earthed system based on active inversion - Google Patents
Flexible control method of zero-sequence voltage of resonant earthed system based on active inversion Download PDFInfo
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- CN104779602A CN104779602A CN201410807088.8A CN201410807088A CN104779602A CN 104779602 A CN104779602 A CN 104779602A CN 201410807088 A CN201410807088 A CN 201410807088A CN 104779602 A CN104779602 A CN 104779602A
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Abstract
The invention discloses a flexible control method of a zero-sequence voltage of a resonant earthed system based on active inversion. The method can realize follow-up control of the zero-sequence voltage, adapts to the resonant earthed system with a certain asymmetric degree, and comprises a removal-changeable harmonicity control neutral point voltage method using a current as a controlled variable, and a damping-changeable control neutral point voltage method using a voltage as a controlled variable. The control method is simple and easy to implement, and can realize the optimal control of a neutral-point displacement voltage and an earthed fault current.
Description
Technical field
What the present invention relates to is a kind of control method of electrical technology, controls the technology of neutral point voltage when specifically normally running based on the resonant earthed system of active inversion.
Background technology
In resonant earthed system, arc suppression coil can produce the inductance current of compensation of ground electric current, the destruction of restricted grounding current, reduces the generation of fault phase recovery voltage and arcing ground over-voltage, improve the safety and reliability of operation of power networks, thus widely use in China's power distribution network.But in actual motion, due to three relatively parameter unbalance or three-phase imbalance loads, cause resonant earthed system neutral point displacement voltage ubiquity, resonance overvoltage when particularly arc suppression coil compensates entirely, larger neutral point displacement voltage makes the weak local discharge breakdown that insulate in electrical network, harmful effect is caused to power distribution network and electric equipment, therefore must be limited by centering point displacement voltage.Specify according to DL/T 620-1997 " overvoltage protection of alternating-current electric device and insulation coordination ": arc suppression coil earthing system, under normal operating conditions, the long-time electric voltage displacement of neutral point should not exceed 15% of system nominal phase voltage.
Traditional residual voltage control program mainly contains: 1) by regulating preset arc suppression coil damping resistance in parallel and post-set arc suppression coils tuning-off degree to suppress neutral point voltage 2) adjusted by three-phase imbalance and mend device and suppress neutral point voltage, mainly contain opening-closing capacitor bank or in certain phase, drop into the static reacance generator of capacitor, thyristor switchable capacitor group and thuristor throw-in and throw-off reactor, GTO Voltage type converter.But such scheme all well can not realize the optimal control of neutral point displacement voltage and earth fault current.
Summary of the invention
Technical problem: technical problem to be solved by this invention is to provide a kind of resonant earthed system residual voltage flexible control method based on active inversion, provide in resonant earthed system the inverter current span controlling residual voltage, to realize the optimal control meeting residual voltage and earth fault current.
Technical scheme: for solving the problems of the technologies described above, the present invention proposes a kind of resonant earthed system residual voltage flexible control method based on active inversion, for as follows respectively with the control method of the grounding system neutral point voltage of the equivalent preset arc suppression coil of the post-set arc suppression coils becoming tuning-off degree, mutative damp rate and preset arc suppression coil:
Scheme a: the post-set arc suppression coils neutral point voltage control method becoming tuning-off degree.
The post-set arc suppression coils overcompensation of change tuning-off degree or undercompensation are by neutral point displacement voltage
u 0within being limited in,
u afor A phase voltage electromotive force,
for coefficient.Inverter Injection Current control coefrficient should meet:
formula 1
formula 2
Become the post-set arc suppression coils overcompensation of tuning-off degree or undercompensation when there is single phase ground fault, for preventing earth current excessive, by earth current
i dbe limited in n(different brackets power distribution network value different) within, inversion control coefficient should meet:
formula 3
formula 4
In formula:
c Σ=
c a+
c b+
c cfor system total distributed capacitance,
c a,
c bwith
c cbe three relatively to distribute total capacitance,
l 1for arc suppression coil equivalent inductance;
u 01for arc suppression coil equivalent inductance is
l 1time neutral point voltage,
v 1for arc suppression coil equivalent inductance is
l 1 tuning-off degree, ;
d 0for natural damping rate,
d 0=1/w
c Σ r Σ,
r Σ=
r a+
r b+
r cfor system distribution all-in resistance,
r a,
r bwith
r cbe three relatively to distribute all-in resistance;
ωfor system angle frequency;
,
be respectively and residual voltage is limited in
the arc suppression coil undercompensation at place and the inverter control coefficient of overcompensation;
,
be respectively and earth current be limited in arc suppression coil undercompensation within n and overcompensation inverter control coefficient;
Formula 1 and formula 3 are post-set arc suppression coils undercompensation restriction neutral point displacement voltage control coefrficient, if neutral point displacement voltage is limited in a certain value
within, only need order
>
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
<
; If both meet a need simultaneously
<
<
;
Formula 2 and formula 4 are post-set arc suppression coils overcompensation restriction neutral point displacement voltage control coefrficient, if neutral point displacement voltage is limited in a certain value
within, only need order
<
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
>
; If both meet a need simultaneously
<
<
;
If both meet value when there is contradiction simultaneously, preferentially get control coefrficient to meet earth current requirement;
Scheme b: the equivalent preset arc suppression coil of mutative damp rate and preset arc suppression coil neutral point voltage control method.
The equivalent preset arc suppression coil of mutative damp rate is by neutral point displacement voltage
u 0be limited in
within, inverter Injection Current control coefrficient should meet:
formula 5
formula 6
The equivalent preset arc suppression coil of mutative damp rate when there is single phase ground fault, for preventing earth current excessive, by earth current
i dwithin being limited in n, inversion control coefficient should meet:
formula 7
formula 8
Formula 5 and formula 7 are neutral point displacement voltage control coefrficient when equivalent post-set arc suppression coils injects positive current in resistance property, if neutral point displacement voltage is limited in a certain value
within, only need control inversion coefficient
<
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
>
; If both meet a need simultaneously
<
<
;
Formula 6 and formula 8 are that equivalent post-set arc suppression coils injects neutral point displacement voltage control coefrficient when bearing current in resistance property, if neutral point displacement voltage is limited in a certain value
within, only need control inversion coefficient
>
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
<
; If both meet a need simultaneously
<
<
;
In above two kinds of control programs: becoming tuning-off degree control neutral point voltage is controlled quentity controlled variable with electric current, is applicable in post-set arc suppression coils grounding system; It is controlled quentity controlled variable with voltage that mutative damp rate controls neutral point voltage, is adapted in all resonant earthed systems, for only changing in formula during post-set arc suppression coils
d 0(being now natural damping rate and damping resistance ratio of damping sum) and tuning-off degree
v 1=0; If both meet simultaneously value there is contradiction time, preferentially get control coefrficient to meet earth current requirement;
Beneficial effect: the resonant earthed system residual voltage flexible control method based on active inversion that the present invention proposes, the method can realize the optimal control of residual voltage and earth current in resonant earthed system, comprises becoming tuning-off degree and mutative damp rate mode controls neutral point voltage.
Accompanying drawing illustrates:
Fig. 1 is based on the resonant earthed system winding diagram of active inversion;
Fig. 2 is based on the resonant earthed system equivalent schematic diagram of active inversion;
Fig. 3 becomes neutral point displacement voltage curve under tuning-off degree mode;
Neutral point displacement voltage curve under Fig. 4 mutative damp rate mode.
Embodiment
For making technical scheme of the invention process and effect clearly understand, below in conjunction with the accompanying drawing in the embodiment of the present invention, give detailed execution mode and specific operation process, as follows:
Step is 1.: when electrical network normally runs, as Fig. 1, by voltage measuring transformer neutral point voltage
u 01;
Step is 2.: the residual voltage control method becoming tuning-off degree mode.
Post-set arc suppression coils equivalent inductance is
l 1time neutral point voltage be
u 01, drop into inverter, make inverter current
(
value As soon as possible Promising Policy [-1,1]),
for dropping into the unsymmetrical current after arc suppression coil, can be detected by current transformer or according to power distribution network over the ground calculation of parameter go out, k is transformer voltage ratio, and inverter and single-phase earthing transformer are equivalent to an impedance
z inverse, then system total impedance and inverter impedance over the ground:
formula 9
formula 10
Neutral point displacement voltage:
formula 11
Make in formula 11
u 0equal
, then post-set arc suppression coils overcompensation or undercompensation are by neutral point displacement voltage
u 0be limited in
within, inverter current control coefrficient should meet:
formula 12
formula 13
When there is single phase ground fault, for preventing earth current excessive (considering with metallic earthing):
formula 14
Make in formula 14
i dequal n, solve:
formula 15
formula 16
Formula 12 and formula 15 are post-set arc suppression coils undercompensation restriction neutral point displacement voltage control coefrficient, if neutral point displacement voltage is limited in a certain value
within, only need order
>
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
<
; If both meet a need simultaneously
<
<
;
Formula 13 and formula 16 are post-set arc suppression coils overcompensation restriction neutral point displacement voltage control coefrficient, if neutral point displacement voltage is limited in a certain value
within, only need order
<
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
>
; If both meet a need simultaneously
<
<
;
Becoming tuning-off degree mode is that controlled quentity controlled variable controls neutral point voltage with electric current, is applicable in post-set arc suppression coils grounding system; If both meet simultaneously value there is contradiction time, preferentially get control coefrficient to meet earth current requirement;
Step is 3.: the residual voltage control method of mutative damp rate mode
Post-set arc suppression coils equivalent inductance is
l 1time neutral point voltage be
u 01, drop into inverter, make inverter current
,
for neutral point displacement voltage (can be measured in real time by voltage transformer), then inverter is equivalent to a resistance element, therefore can be equivalent to preset arc suppression coil,
System is total impedance over the ground:
formula 17
Neutral point displacement voltage:
formula 18
Make in formula 18
u 0equal
, try to achieve:
formula 19
formula 20
When there is single phase ground fault, for preventing earth current excessive (considering with metallic earthing):
formula 21
Make in formula 21
i dequal n, solve:
formula 22
formula 23
Formula 19 and formula 22 are neutral point displacement voltage control coefrficient when equivalent post-set arc suppression coils injects positive current in resistance property, if neutral point displacement voltage is limited in a certain value
within, only need control inversion coefficient
<
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
>
; If both meet a need simultaneously
<
<
;
Formula 20 and formula 23 are that equivalent post-set arc suppression coils injects neutral point displacement voltage control coefrficient when bearing current in resistance property, if neutral point displacement voltage is limited in a certain value
within, only need control inversion coefficient
>
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
<
; If both meet a need simultaneously
<
<
;
Mutative damp rate mode is that controlled quentity controlled variable controls neutral point voltage with voltage, is applicable in all resonant earthed systems, for only changing in formula during post-set arc suppression coils
d 0(being now natural damping rate and damping resistance ratio of damping sum) and tuning-off degree
v 1=0; If both meet value when there is contradiction simultaneously, preferentially get control coefrficient to meet earth current requirement.
Claims (3)
1. based on the resonant earthed system residual voltage flexible control method of active inversion, it is characterized in that, becoming tuning-off degree control method is that controlled quentity controlled variable is by neutral point displacement voltage with electric current
u 0within being limited in,
u afor A phase voltage electromotive force, be coefficient, inverter Injection Current control coefrficient should meet:
formula 1
formula 2
For preventing earth current excessive, by earth current
i dwithin being limited in n, inversion control coefficient should meet:
formula 3
formula 4
In formula:
c Σ=
c a+
c b+
c cfor system total distributed capacitance,
c a,
c bwith
c cbe three relatively to distribute total capacitance,
l 1for arc suppression coil equivalent inductance;
u 01for arc suppression coil equivalent inductance is
l 1time neutral point voltage,
v 1for arc suppression coil equivalent inductance is
l 1tuning-off degree
, ;
d 0for natural damping rate,
d 0=1/w
c Σ r Σ,
r Σ=
r a+
r b+
r cfor system distribution all-in resistance,
r a,
r bwith
r cbe three relatively to distribute all-in resistance;
ωfor system angle frequency;
,
be respectively and residual voltage is limited in
the arc suppression coil undercompensation at place and the inverter control coefficient of overcompensation;
,
be respectively and earth current be limited in arc suppression coil undercompensation within n and overcompensation inverter control coefficient;
Formula 1 and formula 3 are post-set arc suppression coils undercompensation restriction neutral point displacement voltage control coefrficient, if neutral point displacement voltage is limited in a certain value
within, only need order
>
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
<
; If both meet a need simultaneously
<
<
;
Formula 2 and formula 4 are post-set arc suppression coils overcompensation restriction neutral point displacement voltage control coefrficient, if neutral point displacement voltage is limited in a certain value
within, only need order
<
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
>
; If both meet a need simultaneously
<
<
.
2. based on the resonant earthed system residual voltage flexible control method of active inversion, it is characterized in that, mutative damp rate control method is that controlled quentity controlled variable is by neutral point displacement voltage with voltage
u 0be limited in
within,
u afor A phase voltage electromotive force,
for coefficient, inverter Injection Current control coefrficient should meet:
formula 5
formula 6
With the equivalent preset arc suppression coil of mutative damp rate when there is single phase ground fault, for preventing earth current excessive, by earth current
i dwithin being limited in n, inversion control coefficient should meet:
formula 7
formula 8
Formula 5 and formula 7 are neutral point displacement voltage control coefrficient when equivalent post-set arc suppression coils injects positive current in resistance property, if neutral point displacement voltage is limited in a certain value
within, only need control inversion coefficient
<
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
>
; If both meet a need simultaneously
<
<
;
Formula 6 and formula 8 are that equivalent post-set arc suppression coils injects neutral point displacement voltage control coefrficient when bearing current in resistance property, if neutral point displacement voltage is limited in a certain value
within, only need control inversion coefficient
>
; If meet earth current
i dwithin being limited in n, only need control inversion coefficient
<
; If both meet a need simultaneously
<
<
.
3. according to claim 1 and according to claim 2, it is characterized in that, based on the resonant earthed system residual voltage flexible control method of active inversion, become tuning-off degree control method and be applicable to post-set arc suppression coils, mutative damp rate control method is applicable in all resonant earthed systems, for only changing in formula during post-set arc suppression coils
d 0(being now natural damping rate and damping resistance ratio of damping sum) and tuning-off degree
v 1=0; Meet control overflow value at the same time when there is contradiction, preferentially get control coefrficient to meet earth current requirement.
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| CN109782055A (en) * | 2019-04-02 | 2019-05-21 | 云南电网有限责任公司电力科学研究院 | A kind of isolated neutral system capacitance current measurement method and device |
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| CN109980624A (en) * | 2019-04-02 | 2019-07-05 | 云南电网有限责任公司电力科学研究院 | A kind of full compensation implementation method of controllable current source cooperation preset arc suppression coil |
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Cited By (11)
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| CN105977947A (en) * | 2015-12-04 | 2016-09-28 | 长沙理工大学 | Power distribution network active arc extinction device and current control method thereof |
| CN105977947B (en) * | 2015-12-04 | 2018-09-11 | 长沙理工大学 | A kind of active arc-extinction device of power distribution network |
| CN105676071A (en) * | 2016-02-29 | 2016-06-15 | 国家电网公司 | High-resistance control method for fault line selection |
| CN106602540A (en) * | 2016-12-06 | 2017-04-26 | 国网山东省电力公司莱芜供电公司 | Active voltage arc-extinction method applicable to single-phase earth fault of medium voltage distribution network |
| CN107508296A (en) * | 2017-07-26 | 2017-12-22 | 国网山东省电力公司莱芜供电公司 | A kind of system and method for the regulating time for reducing control asymmetrical voltage |
| CN107508296B (en) * | 2017-07-26 | 2020-03-17 | 国网山东省电力公司莱芜供电公司 | System and method for reducing adjustment time for controlling asymmetric voltage |
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| CN109782055A (en) * | 2019-04-02 | 2019-05-21 | 云南电网有限责任公司电力科学研究院 | A kind of isolated neutral system capacitance current measurement method and device |
| CN109901019A (en) * | 2019-04-02 | 2019-06-18 | 云南电网有限责任公司电力科学研究院 | A kind of resonant earthed system capacitance current measurement method and device |
| CN109980624A (en) * | 2019-04-02 | 2019-07-05 | 云南电网有限责任公司电力科学研究院 | A kind of full compensation implementation method of controllable current source cooperation preset arc suppression coil |
| CN109980624B (en) * | 2019-04-02 | 2020-11-17 | 云南电网有限责任公司电力科学研究院 | Full compensation implementation method for matching controllable current source with pre-adjusted arc suppression coil |
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Application publication date: 20150715 |