CN104065059A - Accurate control method for zero-sequence voltage of resonant grounding system - Google Patents
Accurate control method for zero-sequence voltage of resonant grounding system Download PDFInfo
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- CN104065059A CN104065059A CN201410000588.0A CN201410000588A CN104065059A CN 104065059 A CN104065059 A CN 104065059A CN 201410000588 A CN201410000588 A CN 201410000588A CN 104065059 A CN104065059 A CN 104065059A
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- 238000000034 method Methods 0.000 title claims abstract description 24
- 230000001629 suppression Effects 0.000 claims abstract description 102
- 230000007935 neutral effect Effects 0.000 claims abstract description 61
- 238000013016 damping Methods 0.000 claims abstract description 41
- 238000006073 displacement reaction Methods 0.000 claims description 45
- 230000005611 electricity Effects 0.000 claims description 14
- 230000006698 induction Effects 0.000 claims description 3
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- 238000005259 measurement Methods 0.000 description 2
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Abstract
The invention discloses an accurate control method for the zero-sequence voltage of a resonant grounding system. The method is capable of realizing accurate tracking control for the zero-sequence voltage, and comprises a following-setting arc suppression coil overcompensation or undercompensation mode and a pre-setting arc suppression coil parallel damping mode. The optimal control scheme for the damping ratio and the resonance release degree of a power grid is put forward according to control requirements on a neutral point voltage, so as to realize the optimal control for residual currents at the places with single-phase grounding faults and instantaneous faults, of the power grid.
Description
Technical field
What the present invention relates to is a kind of measurement and control method of electrical technology, accurately controls the technology of neutral point voltage when specifically resonant earthed system is normally moved.
Background technology
Arc suppression coil can produce the inductance current of compensation of ground capacitance current at neutral point, greatly reduces fault current, reaches the effect of blow-out, improves the safety and reliability of operation of power networks.In actual motion, resonance overvoltage when neutral point displacement voltage ubiquity, particularly arc suppression coil compensate entirely, larger neutral point displacement voltage is obviously harmful to system safety operation, must be limited by centering point displacement voltage.According to the overvoltage protection of DL/T 620-1997 < < alternating-current electric devices and insulation coordination > >, stipulate: arc suppression coil earthing system; under normal operation, the long-time electric voltage displacement of neutral point should not surpass 15% of system nominal phase voltage.
At present, existing several different methods can record system distributed constant over the ground
with
.Residual voltage control program mainly contains: the mode that 1) preset arc suppression coil adopts also (string) damping to increase ratio of damping limits neutral point displacement voltage, and ratio of damping generally gets 10% ~ 20%, and occurring needs to cut off rapidly damping resistance after earth fault; 2) post-set arc suppression coils increases de-humorous degree and suppresses neutral point voltage when electrical network normally moves, there is earth fault after post-set arc suppression coils adjust to immediately full compensating coefficient.At present, the damping resistance of preset arc suppression coil is generally chosen according to the most serious situation of electrical network nature degree of unbalance, and naturally uneven when the most serious the value of corresponding ratio of damping larger, because damping is in earth fault moment generation active current, the active current of the larger generation of ratio of damping is just larger, and this will be unfavorable for arc extinction; Post-set arc suppression coils takes the mode of overcompensation 15% to move more, though can meet the general control requirement of residual voltage, the less electrical network generation single phase ground fault moment residual flow of system degree of asymmetry is controlled unreasonable; In above scheme, all can not realize the accurate control of neutral point voltage.
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 accuracy control method, provide and realize post-set arc suppression coils equivalent inductance value and the preset arc suppression coil damping resistance value in parallel that resonant earthed system residual voltage is accurately controlled, to realize, meet the optimum control scheme that residual voltage is controlled the de-humorous degree of the electrical network requiring and ratio of damping.
Technical scheme: for solving the problems of the technologies described above, the present invention proposes a kind of resonant earthed system residual voltage accuracy control method is as follows respectively for the control method of post-set arc suppression coils and preset arc suppression coil grounding system neutral point voltage:
Scheme a: post-set arc suppression coils grounding system neutral point voltage accuracy control method.
Post-set arc suppression coils overcompensation or undercompensation are by neutral point displacement voltage
u 0be limited in α
in,
for A phase voltage electromotive force, α is coefficient.The induction of arc suppression coil equivalent electric meets
formula (1)
formula (2)
In formula:
,
for system total distributed capacitance,
,
with
be three total capacitances that relatively distribute
for arc suppression coil equivalent inductance; U0X is that arc suppression coil equivalent inductance is
time neutral point voltage;
for system total electricity that distributes is led,
,
with
be that three total electricity that relatively distribute are led; ω is system angle frequency;
for residual voltage being limited in to the arc suppression coil overcompensation equivalent inductance at α EA place;
for residual voltage is limited in
the arc suppression coil undercompensation equivalent inductance at place;
Formula (1) is for post-set arc suppression coils overcompensation restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
α , a need adjusting arc suppression coil inductance L=
; If neutral point displacement voltage is limited in to certain certain value
αbelow, only need to regulate arc suppression coil inductance L <
;
Formula (2) is for post-set arc suppression coils undercompensation restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
α , a need adjusting arc suppression coil inductance L=
; If neutral point displacement voltage is limited in to certain certain value
α below, only need to regulate arc suppression coil inductance L >
.
Scheme b: preset arc suppression coil grounding system neutral point voltage accuracy control method.
Preset arc suppression coil damping resistance in parallel is limited in neutral point displacement voltage U0
β in,
for power supply phase voltage effective value, damping electricity in parallel is led and should be met
formula (3)
Formula (3) is preset arc suppression coil damping restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
β , only need to regulate arc suppression coil shunt conductance
g l=
g f; If neutral point displacement voltage is limited in to certain certain value
β below, only need to regulate arc suppression coil shunt conductance
g l>
g f.
In above two kinds of control programs: when neutral point displacement voltage is 15% phase voltage, minimum at the ratio of damping and the de-humorous degree that meet the electrical network under voltage control requirement, in formula (1), formula (2) and formula (3), α=β=0.15 o'clock system damping rate is optimum with de-humorous degree.
Beneficial effect: a kind of resonant earthed system residual voltage accuracy control method that the present invention proposes, the method can realize the accurate tracking of residual voltage and control, and comprises the mode of post-set arc suppression coils overcompensation or undercompensation mode, preset arc suppression coil damping.The optimal control scheme that requires to propose electrical network ratio of damping and de-humorous degree according to the control of neutral point voltage, realizes the optimal control of electrical network generation single phase ground fault transient fault place residual flow.
accompanying drawing explanation:
Fig. 1 resonant earthed system equivalent schematic diagram;
Fig. 2 resonant earthed system is normally moved residual voltage track;
During Fig. 3 arc suppression coil different damping resistance in parallel
phase diagram.
Embodiment
For making technical scheme of the invention process and effect more cheer and bright, below in conjunction with the accompanying drawing in the embodiment of the present invention, detailed execution mode and specific operation process have been provided.The track of neutral point voltage is concrete when introducing resonant earthed system and normally move sets forth a kind of resonant earthed system residual voltage accuracy control method, as follows:
Step is 1.: when electrical network normally moves, as Fig. 1, measure neutral point voltage U0X, according to power network line distributed constant over the ground
with
, calculate power network line parameter unbalance vector
:
formula (4)
In above formula:
for system total distributed capacitance,
for system total electricity that distributes is led, CA, CB and CC are three total capacitances that relatively distribute, and GA, GB and GC are that three total electricity that relatively distribute are led;
electric network source A phase voltage;
l xwith
g lXwhile being respectively measurement, arc suppression coil equivalent inductance and equivalent parallel electricity are led, for post-set arc suppression coils
.
Step is 2.: post-set arc suppression coils residual voltage track and control method thereof.
A): post-set arc suppression coils residual voltage track:
The residual voltage track of post-set arc suppression coils is shown in solid line in Fig. 2.Make the admittance of system zero sequence
admittance angle be θ, through O point, make the asymmetric vector of system parameters
vertical line, see pecked line in Fig. 2, the angle of note system nature unbalance voltage and this vertical line is Φ,
during isolated neutral there is nature unbalance voltage in (arc suppression coil equivalent inductance is infinitely great) system
, the asymmetric vector of system parameters
with natural unbalance voltage
the angle number of degrees be
; When arc suppression coil equivalent inductance L reduces and during in undercompensation state gradually from infinity,
, the simultaneous displacement voltage magnitude that residual voltage phase place increases gradually is also increasing, and the residual voltage track of undercompensation state is as arc in Fig. 2; When
, arc suppression coil compensates entirely, and now neutral point voltage reaches maximum, the asymmetric vector of direction and system parameters
opposite direction; Arc suppression coil equivalent inductance continues to reduce,
, arc suppression coil overcompensation, the phase place of residual voltage continues to increase, and simultaneous displacement voltage magnitude reduces, and overcompensation residual voltage track is shown in arc in Fig. 2; When arc suppression coil equivalent inductance is reduced to zero, i.e. neutral-point solid ground, residual voltage amplitude trends towards zero, phase place and the asymmetric vector of system parameters
vertically.Be more than arc suppression coil by infinitely great vanishing process analysis procedure analysis the residual voltage track under preset arc suppression coil.
B): the accurate method for limiting of post-set arc suppression coils residual voltage:
Post-set arc suppression coils equivalent inductance is
time neutral point voltage be that neutral point voltage when arc suppression coil equivalent inductance is L is
formula (5)
Make formula (5) be less than
α , α is coefficient, wherein 0<
α <Um, Um is that arc suppression coil compensates resonance overvoltage entirely,
for power supply phase voltage effective value.Post-set arc suppression coils overcompensation or undercompensation are by neutral point displacement voltage
u 0be limited in
α in, the induction of arc suppression coil equivalent electric meets
formula (6)
in formula (7) formula:
for residual voltage is limited in
α the arc suppression coil overcompensation equivalent inductance at place;
for residual voltage is limited in
α the arc suppression coil undercompensation equivalent inductance at place;
; W is system angle frequency.
Formula (6) is for post-set arc suppression coils undercompensation restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
α , a need adjusting arc suppression coil inductance L=
; If neutral point displacement voltage is limited in to certain certain value
α below, only need to regulate arc suppression coil inductance L >
.
Formula (7) is for post-set arc suppression coils overcompensation restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
α , a need adjusting arc suppression coil inductance L=
; If neutral point displacement voltage is limited in to certain certain value
α below, only need to regulate arc suppression coil inductance L <
.
De-humorous degree when neutral point displacement voltage is 15% phase voltage is minimum, and in formula (6) and formula (7), some system de-humorous degree in α=0.15 is minimum.
Step is 3.: arc suppression coil damping residual voltage track and method for limiting thereof.
A): arc suppression coil damping residual voltage track:
The residual voltage track of arc suppression coil damping is shown in the section dotted line in Fig. 2, in Fig. 2: some Q, G and S are the intersection point of post-set arc suppression coils residual voltage track and arc suppression coil damping residual voltage track.Preset arc suppression coil equivalent inductance, in full compensating coefficient, is shown in formula (8), is incorporated to damping resistance
g lafter, along with the increase of system damping rate, the amplitude of residual voltage reduce and the phase preserving of residual voltage constant, now its track of residual voltage is as the straight line OQ in Fig. 2.
formula (8)
When Fig. 3 is arc suppression coil different damping in parallel
phase diagram, in Fig. 3:
g l1with
g l2for the value before and after the change of arc suppression coil shunt conductance;
with
for arc suppression coil undercompensation shunt conductance is respectively
g l1with
g l2time
admittance angle;
with
for arc suppression coil overcompensation shunt conductance is respectively
g l1with
g l2time
admittance angle.As seen from the figure: during arc suppression coil overcompensation
, electricity is led increase
g l1<
g l2,
phase angle increase; During arc suppression coil undercompensation
, electricity is led increase
g l1<
g l2,
phase angle reduce.Therefore, when
g lduring increase, arc suppression coil undercompensation, residual voltage phase angle increases, arc suppression coil overcompensation, residual voltage phase angle reduces, and along with the amplitude of the increase residual voltage of ratio of damping reduces.When
g ldirection and the asymmetric vector of system parameters of residual voltage during trend infinitely great (neutral-point solid ground)
on the contrary.By above analysis, can show that arc suppression coil is under overcompensation or undercompensation state the residual voltage track after damping resistance in parallel respectively in Fig. 2 as shown in arc OG and OS.
B): arc suppression coil the accurate method for limiting of damping residual voltage:
When preset arc suppression coil normally moves, reactive current is in full compensating coefficient, and equivalent inductance meets
<L<
,
l x,
for α=0.15 o'clock arc suppression coil equivalent inductance in formula (6) and formula (7), residual voltage when arc suppression coil does not connect damping is greater than 15% phase voltage, need to increase ratio of damping and suppress neutral point displacement voltage.
Note arc suppression coil equivalent inductance is
l x, equivalent parallel electricity lead into
g lXtime neutral point voltage be
, arc suppression coil equivalent inductance be L, equivalent parallel electricity lead into
g ltime neutral point voltage be
formula (9)
Make formula (9) be less than
β , β is coefficient, wherein 0<
β <Un, Un is neutral point displacement voltage when arc suppression coil compensates entirely under resonant earthed system natural damping rate,
for power supply phase voltage effective value, neutral point displacement voltage U0 is limited in
β in, damping electricity in parallel is led and should be met
formula (10)
In formula
; If neutral point displacement voltage is limited in to certain certain value
β , only need to regulate arc suppression coil shunt conductance
g l=
g f; If neutral point displacement voltage is limited in to certain certain value β
below, only need to regulate arc suppression coil shunt conductance
g l>
g f.
Ratio of damping when neutral point displacement voltage is 15% phase voltage is minimum, and in formula (10), β=0.15 o'clock system damping rate is minimum.
Claims (3)
1. a resonant earthed system residual voltage accuracy control method, is characterized in that, post-set arc suppression coils overcompensation or undercompensation are by neutral point displacement voltage
u 0be limited in α
in,
for A phase voltage electromotive force, α is coefficient;
The induction of arc suppression coil equivalent electric meets
formula (1)
formula (2)
In formula:
,
for system total distributed capacitance,
,
with
be three total capacitances that relatively distribute
for arc suppression coil equivalent inductance; U0X is that arc suppression coil equivalent inductance is
time neutral point voltage;
for system total electricity that distributes is led,
,
with
be that three total electricity that relatively distribute are led; ω is system angle frequency;
for residual voltage being limited in to the arc suppression coil overcompensation equivalent inductance at α EA place;
for residual voltage is limited in
the arc suppression coil undercompensation equivalent inductance at place;
Formula (1) is for post-set arc suppression coils overcompensation restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
α , a need adjusting arc suppression coil inductance L=
; If neutral point displacement voltage is limited in to certain certain value
αbelow, only need to regulate arc suppression coil inductance L <
;
Formula (2) is for post-set arc suppression coils undercompensation restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
α , a need adjusting arc suppression coil inductance L=
; If neutral point displacement voltage is limited in to certain certain value
α below, only need to regulate arc suppression coil inductance L >
.
2. a resonant earthed system residual voltage accuracy control method, is characterized in that, preset arc suppression coil damping resistance in parallel is limited in neutral point displacement voltage U0
β in,
for power supply phase voltage effective value, damping electricity in parallel is led and should be met
formula (3)
Formula (3) is preset arc suppression coil damping restriction neutral point displacement voltage calculating formula, if neutral point displacement voltage is limited in to certain certain value
β , only need to regulate arc suppression coil shunt conductance
g l=
g f; If neutral point displacement voltage is limited in to certain certain value
β below, only need to regulate arc suppression coil shunt conductance
g l>
g f.
3. according to the device of claim 1 and the full compensation of a kind of single phase ground fault fundamental current claimed in claim 2, it is characterized in that, when neutral point displacement voltage is 15% phase voltage, minimum at the ratio of damping and the de-humorous degree that meet the electrical network under voltage control requirement, in formula (1), formula (2) and formula (3), α=β=0.15 o'clock system damping rate is optimum with de-humorous degree.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779602A (en) * | 2014-12-23 | 2015-07-15 | 中国矿业大学 | Flexible control method of zero-sequence voltage of resonant earthed system based on active inversion |
| CN108321784A (en) * | 2018-01-15 | 2018-07-24 | 中国矿业大学 | A kind of neutral ground method based on arc suppression coil and constant watt current |
| CN109596932A (en) * | 2018-11-08 | 2019-04-09 | 杭州求是电力技术有限公司 | Resonant earthed system zero sequence parameter measurement and ground voltage control method based on virtual ground principle |
-
2014
- 2014-01-02 CN CN201410000588.0A patent/CN104065059A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779602A (en) * | 2014-12-23 | 2015-07-15 | 中国矿业大学 | Flexible control method of zero-sequence voltage of resonant earthed system based on active inversion |
| CN108321784A (en) * | 2018-01-15 | 2018-07-24 | 中国矿业大学 | A kind of neutral ground method based on arc suppression coil and constant watt current |
| CN109596932A (en) * | 2018-11-08 | 2019-04-09 | 杭州求是电力技术有限公司 | Resonant earthed system zero sequence parameter measurement and ground voltage control method based on virtual ground principle |
| CN109596932B (en) * | 2018-11-08 | 2020-10-16 | 杭州求是电力技术有限公司 | Zero sequence parameter measurement and grounding voltage control method for resonance grounding system |
| US11143712B2 (en) | 2018-11-08 | 2021-10-12 | Hangzhou Qiuchuang Electric Power Science & Technology Co., Ltd. | Zero-sequence parameter measurement and ground voltage control method for resonant ground system based on virtual ground principle |
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