CN107612034A - A kind of suppressing method of energy accumulation current converter transient state excessively stream - Google Patents
A kind of suppressing method of energy accumulation current converter transient state excessively stream Download PDFInfo
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- CN107612034A CN107612034A CN201710998621.7A CN201710998621A CN107612034A CN 107612034 A CN107612034 A CN 107612034A CN 201710998621 A CN201710998621 A CN 201710998621A CN 107612034 A CN107612034 A CN 107612034A
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Abstract
A kind of suppressing method of energy accumulation current converter transient state excessively stream, the suppression of energy accumulation current converter transient state excessively stream under grid failure state is realized by current transformer port electric voltage feed forward and change virtual impedance method.Comprise the following steps that：(1) one-level excessively stream threshold value i is setover1With two level excessively stream threshold value iover2；(2) virtual resistance R is setvWith virtual inductor Lv；(3) energy accumulation current converter port voltage is sampled and carries out Clarke transform, obtain current transformer port voltage v under two-phase rest frameα、vβ；(4) to energy accumulation current converter inductance L current samples and the maximum i of the absolute value of three-phase current is calculatedpeak；(5) rated current flows into current transformer power unit direction just, to carry out Clarke transform to energy accumulation current converter inductive current, obtaining inductive current i under two-phase rest frameα、iβ；(6) when detecting current maxima ipeakIn iover1<ipeak≤iover2During section, the modulation voltage e of switching energy accumulation current converter portα、eβ.The present invention can suppress energy accumulation current converter overcurrent, reach fault ride-through of power grid and the purpose of self-protection when power network such as falls at the failure.
Description
Technical field
The present invention relates to a kind of suppressing method of energy accumulation current converter transient state excessively stream, more particularly to a kind of energy accumulation current converter power network
The suppressing method of transient state excessively stream in the case of failure.
Background technology
Energy accumulation current converter is as power electronic equipment, and conveyance capacity is limited, and its steady-state current amplitude limit and transient state excessively stream suppress
Always the emphasis of researcher's concern, the suppressing method for studying its transient state excessively stream are significant.
Traditional suppressing method, the scheme of generally use pulse blocking are short after detecting that electric current exceedes excessively stream threshold value
Time block device for power switching driving pulse, be delayed certain time or detect electric current drop to pulse restart threshold value with
When lower, the driving pulse of device for power switching is reopened.Patent 200910109535.1《A kind of double-fed induction generator is worn
The more device and method of electric network fault》I.e. in this way.But pulse blocking scheme is due to directly having interrupted portion of electrical current
Path, output current short interruptions can be produced, and then cause chugging.And steady-state current amplitude limit method is generally limited by control
The time constant of device, it is poor to transient state excessively stream inhibition.So in steady-state current amplitude limit and traditional pulse blocking suppression side
, it is necessary to a kind of excessive scheme, the excessively stream in the case of tackling in addition to the limit faults such as short circuit between case.
The content of the invention
Lack lacking for excessively stream suppressing method in addition to the limit faults such as short circuit in conventional overcurrent Restrain measurement to overcome
Point, the present invention propose a kind of suppressing method of energy accumulation current converter transient state excessively stream, when power network such as falls at the failure, can suppress to store up
Energy current transformer overcurrent, reaches fault ride-through of power grid and the purpose of self-protection.
The temporary current control of energy accumulation current converter is divided into three kinds of states.The first is controller limited current state, generally by adjusting
Device closed loop control current amplitude, stable state maximum is limited, excessively stream will not now occur.Second is one-level over-current state, now
Electric current exceedes one-level overcurrent threshold value, but still less than two level overcurrent threshold value, now can be with by adjusting appropriate control method
Suppress the generation of excessively stream.The third is two level over-current state, and now electric current exceedes two level overcurrent threshold value, should now take pulse
The method of block.If electric current exceedes three-level overcurrent threshold value, emergency shutdown operation should be performed.
The present invention realizes energy storage under one-level over-current state by current transformer port electric voltage feed forward and change virtual impedance method
The suppression of current transformer transient state excessively stream, step are as follows：
The 1st, the one-level excessively stream threshold value i of energy accumulation current converter is setover1With two level excessively stream threshold value iover2；
The 2nd, virtual resistance R is setvWith virtual inductor Lv；
3rd, energy accumulation current converter port voltage is sampled and carries out Clarke transform, obtain current transformer under two-phase rest frame
Port voltage vα、vβ；
4th, to energy accumulation current converter inductance L current samples, and the maximum i of the absolute value of three-phase current is calculatedpeak；
5th, rated current flows into current transformer power unit direction just, Clarke change to be carried out to energy accumulation current converter inductive current
Change, obtain inductive current i under two-phase rest frameα、iβ；
6th, when detecting three-phase current maximum ipeakIn iover1<ipeak≤iover2During section, switch energy accumulation current converter
The modulation voltage e of portα、eβ, calculation is shown below：
eα=vα+iαkRv+iβω(kLv+L)
eβ=vβ-iαω(kLv+L)+iβkRv
ω is energy accumulation current converter port voltage angular frequency in formula, and k is impedance coefficient, and solution formula is：
The use of impedance coefficient k can make the modulation voltage of the current transformer end mouth excess smoothness when current limliting is cut out,
Reduce transient state impact.
The present invention provides a kind of simple and effective suppression for the transient state excessively stream in the case of the non-shorting failure of energy accumulation current converter
Method.This have the advantage that：The fast response time in overcurrent, electric current is not produced and is interrupted suddenly, suppressing excessively stream
While, effectively it is lowered into pulse blocking shape probability of state.Moreover, the method for the invention calculating process is simple, it is easy to several
Word controller is realized.
Brief description of the drawings
Fig. 1 is energy accumulation current converter electric topology figure；
Fig. 2 is that the electric current with virtual resistance transmits schematic diagram；
Fig. 3 is that excessively stream suppresses control block diagram；
Current waveform figure when Fig. 4 is is not enabled on electric network fault in the case of excessively stream suppressing method；
Current waveform figure when Fig. 5 is electric network fault in the case of enabled excessively stream suppressing method.
Embodiment
The present invention is further illustrated below in conjunction with the drawings and specific embodiments.
As shown in figure 1, the dc bus end connection energy-storage units of the energy accumulation current converter of the application present invention, power cell pass through
The filter circuit of LC compositions is current transformer port, is generally attached to power network, wherein L is filter inductance, and C is filter capacitor.Take
It is just current transformer port voltage v that current transformer port, which flows to power cell direction,a、vb、vcFlow to power cell voltage ea、eb、ec's
Electric current is ia、ib、ic.Fig. 2 show the electric current transmission schematic diagram with virtual resistance, and E is power cell voltage vector in figure, V
For current transformer port voltage vector, I is the current phasor flowed through on net side filter inductance L.Not during band virtual impedance, electric current can be with
It is expressed as following formula：
After virtual impedance, electric current can be expressed as following formula：
Wherein j is that vector imaginary part represents symbol, and ω is energy accumulation current converter port voltage angular frequency, RvFor virtual resistance, LvFor
Virtual inductor value.
Power cell voltage reference value is arranged to the same of current transformer port voltage by the present invention in energy accumulation current converter excessively stream
When introduce variable virtual impedance kRv+jωkLv, k is impedance coefficient, inhibits over-current state to greatest extent.
Energy accumulation current converter transient state excessively stream suppressing method of the present invention is as shown in figure 3, step is as follows：
The 1st, the one-level excessively stream threshold value i of energy accumulation current converter is setover1With two level excessively stream threshold value iover2。
The 2nd, virtual resistance R is setvWith virtual inductor Lv。
3rd, energy accumulation current converter port voltage is sampled and carries out Clarke transform, obtain current transformer under two-phase rest frame
Port voltage vα、vβ。
4th, to energy accumulation current converter inductance L current samples and the maximum i of the absolute value of three-phase current is calculatedpeak。
5th, rated current flows into current transformer power unit direction just, Clarke change to be carried out to energy accumulation current converter inductive current
Change, obtain inductive current i under two-phase rest frameα、iβ。
6th, when detecting three-phase current maximum ipeakIn iover1<ipeak≤iover2During section, switch energy accumulation current converter
The modulation voltage e of portα、eβ, calculation is shown below：
eα=vα+iαkRv+iβω(kLv+L)
eβ=vβ-iαω(kLv+L)+iβkRv
ω is energy accumulation current converter port voltage angular frequency in formula, and k is impedance coefficient, and solution formula is：
The use of impedance coefficient k can make the modulation voltage of the current transformer end mouth excess smoothness when current limliting is cut out,
Reduce transient state impact.
By taking 50kW current transformers as an example, simulating, verifying control method of the present invention.Current transformer rated voltage 190V, specified electricity
152A is flowed, one-level excessively stream threshold value 325A is set, two level excessively stream threshold value 400A is set, the Ω of virtual resistance value 0.1, virtual inductor are set
Value 0.25mH.Fall failure when three-phase occurs for power network, when being not enabled on suppressing method of the present invention, voltage current waveform such as Fig. 4
It is shown.It is about 560V in electric network fault starting transient current peak value, recovers transient current peak value about 600A.Using of the present invention
During suppressing method, voltage current waveform is as shown in Figure 5.It is about 360V in electric network fault starting transient current peak value, recovers transient state
Current peak about 395A.As can be seen that the transient state excessively stream suppressing method of the present invention makes energy accumulation current converter during electric network fault cross stream peak
Value declines about 200A, and in process of inhibition, electric current does not occur the phenomenon of short interruptions, significant effect.
Claims (1)
- A kind of 1. suppressing method of energy accumulation current converter transient state excessively stream, it is characterised in that：Described control method passes through current transformer end Mouth electric voltage feed forward and change virtual impedance method are realized；Comprise the following steps that：(1) the one-level excessively stream threshold value i of energy accumulation current converter is setover1With two level excessively stream threshold value iover2；(2) virtual resistance R is setvWith virtual inductor Lv；(3) energy accumulation current converter port voltage is sampled and carries out Clarke transform, obtain current transformer end under two-phase rest frame Mouth voltage vα、vβ；(4) to energy accumulation current converter inductance L current samples and the maximum i of the absolute value of three-phase current is calculatedpeak；(5) rated current flows into current transformer power unit direction just, Clarke transform to be carried out to energy accumulation current converter inductive current, Obtain inductive current i under two-phase rest frameα、iβ；(6) when detecting current maxima ipeakIn iover1<ipeak≤iover2During section, the tune of switching energy accumulation current converter port Voltage e processedα、eβ, calculation is shown below：eα=vα+iαkRv+iβω(kLv+L)eβ=vβ-iαω(kLv+L)+iβkRvω is energy accumulation current converter port voltage angular frequency in formula, and k is impedance coefficient, and solution formula is：<mrow> <mi>k</mi> <mo>=</mo> <mfrac> <mrow> <msub> <mi>i</mi> <mrow> <mi>p</mi> <mi>e</mi> <mi>a</mi> <mi>k</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>i</mi> <mrow> <mi>o</mi> <mi>v</mi> <mi>e</mi> <mi>r</mi> <mn>1</mn> </mrow> </msub> </mrow> <msub> <mi>i</mi> <mrow> <mi>o</mi> <mi>v</mi> <mi>e</mi> <mi>r</mi> <mn>1</mn> </mrow> </msub> </mfrac> <mo>.</mo> </mrow>
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112311216A (en) * | 2020-10-15 | 2021-02-02 | 湖南大学 | Current transformer overcurrent suppression method and device |
| CN116865223A (en) * | 2023-07-04 | 2023-10-10 | 南方电网科学研究院有限责任公司 | Fault current limiting method and device for grid-structured fan converter and storage medium |
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| CN102623992A (en) * | 2012-04-12 | 2012-08-01 | 山东大学 | Method for islanding microgrid control and optimization based on rotating coordinate virtual impedance |
| CN103715693A (en) * | 2013-11-11 | 2014-04-09 | 国家电网公司 | Voltage compensation and fault current limiting hybrid system and control method thereof |
| CN106712088A (en) * | 2017-01-17 | 2017-05-24 | 燕山大学 | Low-voltage micro-grid inverter control system based on virtual impedance and virtual power source |
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2017
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| CN102623992A (en) * | 2012-04-12 | 2012-08-01 | 山东大学 | Method for islanding microgrid control and optimization based on rotating coordinate virtual impedance |
| CN103715693A (en) * | 2013-11-11 | 2014-04-09 | 国家电网公司 | Voltage compensation and fault current limiting hybrid system and control method thereof |
| CN106712088A (en) * | 2017-01-17 | 2017-05-24 | 燕山大学 | Low-voltage micro-grid inverter control system based on virtual impedance and virtual power source |
Non-Patent Citations (2)
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| JINWEI HE等: "Analysis, Design, and Implementation of Virtual Impedance for Power Electronics Interfaced Distributed Generation", 《IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112311216A (en) * | 2020-10-15 | 2021-02-02 | 湖南大学 | Current transformer overcurrent suppression method and device |
| CN116865223A (en) * | 2023-07-04 | 2023-10-10 | 南方电网科学研究院有限责任公司 | Fault current limiting method and device for grid-structured fan converter and storage medium |
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Application publication date: 20180119 |