CN104483639A - Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer - Google Patents
Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer Download PDFInfo
- Publication number
- CN104483639A CN104483639A CN201410723535.1A CN201410723535A CN104483639A CN 104483639 A CN104483639 A CN 104483639A CN 201410723535 A CN201410723535 A CN 201410723535A CN 104483639 A CN104483639 A CN 104483639A
- Authority
- CN
- China
- Prior art keywords
- phase
- formula
- voltage
- magnetic flux
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Protection Of Transformers (AREA)
Abstract
The invention discloses a residual magnetism estimation method for non-fault tripping of a YNd11 type three-phase combined transformer. The method comprises the following steps: firstly sampling voltage and current waveforms of the YNd11 type three-phase combined transformer through a mutual inductor by a signal acqusition device to obtain voltage and current instantaneous values, and solving the plural form of each electrical quantity through a fourier algorithm to further obtain a power factor angle and a core steady-state flux peak; then determining a first open phase and a first open phase drop-out voltage phase angle according to the sampled three-phase current waveform; finally estimating three-phase core residual magnetism according to the change situation of winding voltage in the tripping process and the relation of the voltage with core flux. According to the method, only the three-phase voltage and current waveforms during operation of the YNd11 type three-phase combined transformer are required to be sampled, and the power factor angle and the core steady-state flux peak in the steady-state operation are obtained through data processing, so the residual magnetism of a core can be estimated thereby; related parameters are easy to acquire; the method can be conveniently used for actual engineering estimation.
Description
Technical field
The invention belongs to transformer remanent magnetism method of estimation technical field, be specifically related to the remanent magnetism method of estimation of a kind of YNd11 type three-phase group formula transformer non-faulting tripping operation.
Background technology
YNd11 type three-phase group formula transformer is made up of three single transformers, and iron core builds up primarily of siliconized plate, the star-like connection of former limit winding and neutral ground, vice-side winding triangle junction.Because each phase magnetic flux closes along respective magnetic circuit, therefore its magnetic circuit system has nothing to do each other, and in supply frequency and umber of turn one timing, each phase iron core magnetic flux determines (ignoring coil resistance and leakage flux) by winding impressed voltage.
Because siliconized plate belongs to ferromagnetic material, there is hysteresis, after transformer separating brake, external magnetic field is cancelled, and ferromagnetics still can keep original part magnetic, and make transformer fe in-core leave part magnetic flux, this magnetic flux is called iron core remanent magnetism.Therefore can be similar to and to think after transformer separating brake that remanent magnetism over time and not obvious, remanent magnetism is approximately equal to separating brake moment iron core magnetic flux.Former limit three-phase current equal and opposite in direction when YNd11 type three-phase group formula transformer normally runs in three-phase symmetrical system, phase place mutual deviation 120 °, due to the nature disjunction when current over-zero of each phase isolating switch, therefore three-phase separating brake moment non-synchronous, this process will cause the change of winding impressed voltage, and then affects iron core remanent magnetism.And when transformer during no-load closing, because core material excitation property has nonlinear characteristic, affect by iron core remanent magnetism and breaker closing phase angle, the saturated of iron core may be caused, transformer is caused to produce very large exciting current in the side of voltage jump, maximum 6 ~ 8 times of reaching rated current of its numerical value, this electric current is just called the excitation surge current of transformer.Due to excitation surge current amplitude very greatly and only flow through transformer side, by causing Differential Protection of Transformer to produce very large difference stream, causing differential protection misoperation trip, making putting into operation time and again unsuccessfully of transformer; The excitation surge current that numerical value is very large also can cause transformer and isolating switch because of electric power excessive and impaired; Excitation surge current also may bring out transformer that other transformer station contiguous etc. running and produce " sympathetic inrush " and mistrip, causes large-area power-cuts; A large amount of harmonic waves wherein also can cause serious pollution to the electrical network quality of power supply.
Phase selection technology be a kind of novel electric power apparatus proposed along with the development of switching technique close means, it suppresses the principle of excitation surge current to be select suitable switching-on phase according to the remanent magnetism in separating brake back core, control isolating switch dynamic/static contact to carry out switch in the designated phase angle moment of system voltage or current waveform and close, what when making combined floodgate, remanent magnetism and magnetic bias can be similar to cancels out each other, thus avoid the supersaturation of transformer core magnetic flux, fundamentally reach the object weakening excitation surge current.
The existing multiple traditional counting model about remanent magnetism or magnetic field comprises Product model, Preisach model, Stoner-Wohlfarth model, but above Model Calculating Method all relates to the parameter that part is not directly measured, and utilize the requirement of software emulation transformer remanent magnetism to compare accurate simulation to system works behavior, model buildings is comparatively complicated, therefore practicality is all little in the concrete estimation of transformer core remanent magnetism.
Summary of the invention
In order to solve above-mentioned prior art Problems existing, the invention provides the remanent magnetism method of estimation of a kind of YNd11 type three-phase group formula transformer non-faulting tripping operation, the method only need be sampled YNd11 type three-phase group formula transformer three-phase voltage current waveform when running, by the power-factor angle under data processing acquisition steady-state operation and iron core stable state magnetic flux peak value, iron core remanent magnetism can be estimated accordingly, correlation parameter easily obtains, in can estimating for Practical Project easily.
In order to achieve the above object, the present invention adopts following technical scheme:
The remanent magnetism method of estimation of YNd11 type three-phase group formula transformer non-faulting tripping operation, comprises the steps:
When step 1:YNd11 type three-phase group formula transformer runs, signal pickup assembly is sampled by the voltage current waveform of mutual inductor to YNd11 type three-phase group formula transformer, obtains electric current and voltage instantaneous value;
Step 2: obtain YNd11 type three-phase group formula transformer stable state three-phase voltage, electric current plural form by fourier algorithm, obtains power-factor angle
and iron core stable state magnetic flux peak value φ
m, described iron core stable state magnetic flux peak value
wherein: U
mrepresent phase voltage amplitude, N represents umber of turn, and ω is system angle frequency;
Step 3: the three-phase current waveform of acquisition of sampling according to step 1, determines the first mutually disconnected and first phase drop-out voltage phase angle that breaks
or
described head breaks the phase referring to mutually and first disconnect, namely when first the electric current of certain phase is reduced to zero and remain unchanged, then and disconnected phase headed by this phase;
Step 4: estimation tri-phase iron core remanent magnetism
Suppose that first breaking is A phase mutually, and first disconnected phase voltage phase angle is δ, it is still approximate such as formula shown in (5) that A phase cut-offs rear three-phase windings voltage, cut-offfing rear three-phase windings voltage mutually because head is disconnected is similar to constant, therefore magnetic flux is still by formula (7) change, three-phase current is such as formula shown in (8);
From formula (8), during ω t=δ+30 °, C phase current reduces to zero, and this phase isolating switch cut-offs.After C phase is cut-off, three-phase windings voltage is approximately
Three-phase current is approximately
According to formula (7), C phase cut-offs moment ω t=δ+30 °, and tri-phase iron core magnetic flux is such as formula shown in (11);
According to the law of electromagnetic induction, the three-phase being cut-off the generation of rear three-phase windings voltage by C phase responds to magnetic flux φ in advance
ay, φ
by, φ
cyfor formula (12);
According to continuity of magnetic flux theorem, this moment magnetic flux cannot suddenly change, and passes to the pre-induction magnetic flux of offsetting this moment by producing such as formula the magnetic bias shown in (13);
Therefore after C phase disconnects, tri-phase iron core magnetic flux is formula (11), (12), (13) formula sum and formula (14);
From formula (10), B phase will the current over-zero blow-out when ω t=δ+120 °; Bring ω t=δ+120 ° into formula (14), can obtain tri-phase iron core remanent magnetism is formula (15);
Because three-phase system has symmetry, therefore disconnected phase time headed by B, C phase, first mutually disconnected and another two-phase flux change rule is identical with above-mentioned situation, can obtain first disconnected phase remanent magnetism expression formula accordingly, shown in (16);
Normal when running the advanced first disconnected Xiang Weici of 120 ° mutually of voltage-phase to break phase, this phase remanent magnetism is for shown in formula (17)
Normal when running the voltage-phase delayed head Xiang Weimo of 120 ° mutually that breaks to break phase, this phase remanent magnetism is for shown in formula (18)
φ
md＝φ
msin(δ-90°) (18)。
Compared to the prior art comparatively, the present invention possesses following advantage:
1, correlation parameter easily obtains.Namely all parameters of this remanent magnetism method of estimation are all by directly measuring or indirect calculation acquisition.
2., compared to software emulation YNd11 type three-phase group formula transformer remanent magnetism, without the need to building complicated system model, the convenient engineering that is used for is estimated.
Accompanying drawing explanation
Fig. 1 is voltage-current relationship figure.
Fig. 2 is YNd11 type three-phase group formula transformer Connecting groups schematic diagram.
Fig. 3 is realistic model equivalent circuit diagram.
Fig. 4 is for estimating magnetic flux and emulation flux waveforms comparison diagram.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail:
When transformer runs, signal pickup assembly carries out sampling by the voltage current waveform of mutual inductor to YNd11 type three-phase group formula transformer and obtains electric current and voltage instantaneous value, obtains stable state three-phase voltage plural form by fourier algorithm
and electric current plural form
such as formula (1), (2).Wherein U
mrepresent phase voltage amplitude, α represents A phase voltage phase angle, I
mrepresent line current amplitude, β represents A phase current phase angle, and power-factor angle is each phase voltage and current phase angle difference, therefore
If A phase voltage phase angle α=0 °, stable state three-phase voltage time-domain expression u can be obtained by (1), (2)
a(t), u
b(t), u
c(t), and electric current time-domain expression i
a(t), i
b(t), i
c(t), such as formula (3), (4).
Wherein ω is system angle frequency.
Because transformer primary side winding is YN connection, each phase winding voltage u during normal operation
aX, u
bY, u
cZbe each phase voltage, shown in (5).
According to Faraday's electromagnetic induction law,
Wherein u represents winding voltage, and φ represents iron core magnetic flux, and N represents umber of turn.
Then tri-phase iron core magnetic flux φ
a, φ
b, φ
ccan be expressed as
Wherein iron core stable state magnetic flux peak value is
In Fig. 1, u represents former limit phase voltage, and i represents phase current, and because isolating switch during separating brake will the nature disjunction when current over-zero, therefore first disconnected phase voltage phase angle is
or
Suppose that first breaking is A phase mutually, cut-offfing rear electric parameters can analyze with symmetrical component method.For YNd11 type group formula three-phase transformer, as shown in Figure 2, when residual voltage is added on transformer YN side, zero-sequence current forms loop with clicking and entering by this side winding neutrality, therefore can think that zero sequence impedance is approximately equal to transformer leakage reactance in sequence net, and because the impedance of transformer sequence is much smaller than loaded impedance, A phase can be obtained accordingly and cut-off rear three-phase windings voltage, still such as formula shown in (5), tri-phase iron core magnetic flux is still by formula (7) change, and three-phase current is such as formula shown in (8).
From formula (8), C phase current zero passage during ω t=δ+30 °, isolating switch blow-out, is equivalent to former limit A, the C two-phase broken string of three phase transformers, analyzes equally with symmetrical component method.
Can obtain after C phase cut-offs, former limit three-phase windings voltage is approximately
Former limit three-phase current is approximately
According to formula (7), C phase is cut-off the moment (ω t=δ+30 °) tri-phase iron core magnetic flux is such as formula shown in (11).
According to the law of electromagnetic induction, the three-phase being cut-off the generation of rear three-phase windings voltage by C phase responds to magnetic flux φ in advance
ay, φ
by, φ
cyfor formula (12)
According to continuity of magnetic flux theorem, this moment magnetic flux cannot suddenly change, and passes to the pre-induction magnetic flux of offsetting this moment by producing such as formula the magnetic bias shown in (13).
Therefore after C phase disconnects, tri-phase iron core magnetic flux is formula (11), (12), (13) formula sum.
From formula (10), B phase isolating switch will cut-off when ω t=δ+120 ° in current over-zero blow-out.Bring ω t=δ+120 ° into formula (14), can obtain tri-phase iron core remanent magnetism is
Because three-phase system has symmetry, therefore disconnected phase time headed by B, C phase, first mutually disconnected and another two-phase flux change rule is identical with above-mentioned situation, can obtain first disconnected phase remanent magnetism expression formula accordingly, shown in (16).
Normal when running the advanced first disconnected Xiang Weici of 120 ° mutually of voltage-phase to break phase, this phase remanent magnetism is
Normal when running the voltage-phase delayed head Xiang Weimo of 120 ° mutually that breaks to break phase, this phase remanent magnetism is
φ
md＝φ
msin(δ-90°) (18)。
Embodiment
Build realistic model as shown in Figure 3, in figure: X
lrepresent line impedance, TV represents voltage transformer (VT), and TA represents current transformer, and QK represents three-phase breaker.Carry out sub-switching operation to three-phase breaker QK, signal pickup assembly gathers three-phase voltage current waveform by TA and TV.In this emulation, power-factor angle
iron core stable state magnetic flux peak value φ
m=47.83wb*N, first breaking is A phase mutually, first disconnected phase angle
the first disconnected phase separating brake moment as shown in Figure 4.Utilize formula (16), (17) tri-phase iron core magnetic flux and in (18) matching separating brake process, compare with emulation magnetic flux, as can be seen from the figure: in separating brake process, estimate that magnetic flux can Curve fitting simulation magnetic flux preferably, when after the equal separating brake of three-phase, estimate that between magnetic flux and emulation magnetic flux, error is very little, this method can effectively estimate tri-phase iron core remanent magnetism as seen.
Below by reference to the accompanying drawings the specific embodiment of the present invention is described; but these explanations can not be understood to limit scope of the present invention; protection scope of the present invention is limited by the claims of enclosing, and any change on the claims in the present invention basis is all protection scope of the present invention.
Claims (1)
- The remanent magnetism method of estimation of 1.YNd11 type three-phase group formula transformer non-faulting tripping operation, is characterized in that: comprise the steps:When step 1:YNd11 type three-phase group formula transformer runs, signal pickup assembly is sampled by the voltage current waveform of mutual inductor to YNd11 type three-phase group formula transformer, obtains electric current and voltage instantaneous value;Step 2: obtain YNd11 type three-phase group formula transformer stable state three-phase voltage, electric current plural form by fourier algorithm, obtains power-factor angle and iron core stable state magnetic flux peak value φ m, described iron core stable state magnetic flux peak value wherein: U mrepresent phase voltage amplitude, N represents umber of turn, and ω is system angle frequency;Step 3: the three-phase current waveform of acquisition of sampling according to step 1, determines the first mutually disconnected and first phase drop-out voltage phase angle that breaks or described head breaks the phase referring to mutually and first disconnect, namely when first the electric current of certain phase is reduced to zero and remain unchanged, then and disconnected phase headed by this phase;Step 4: estimation tri-phase iron core remanent magnetismSuppose that first breaking is A phase mutually, and first disconnected phase voltage phase angle is δ, it is still approximate such as formula shown in (5) that A phase cut-offs rear three-phase windings voltage, cut-offfing rear three-phase windings voltage mutually because head is disconnected is similar to constant, therefore magnetic flux is still by formula (7) change, three-phase current is such as formula shown in (8);From formula (8), during ω t=δ+30 °, C phase current reduces to zero, and this phase isolating switch cut-offs.After C phase is cut-off, three-phase windings voltage is approximatelyThree-phase current is approximatelyAccording to formula (7), C phase cut-offs moment ω t=δ+30 °, and tri-phase iron core magnetic flux is such as formula shown in (11);According to the law of electromagnetic induction, the three-phase being cut-off the generation of rear three-phase windings voltage by C phase responds to magnetic flux φ in advance ay, φ by, φ cyfor formula (12);According to continuity of magnetic flux theorem, this moment magnetic flux cannot suddenly change, and passes to the pre-induction magnetic flux of offsetting this moment by producing such as formula the magnetic bias shown in (13);Therefore after C phase disconnects, tri-phase iron core magnetic flux is formula (11), (12), (13) formula sum and formula (14);From formula (10), B phase will the current over-zero blow-out when ω t=δ+120 °; Bring ω t=δ+120 ° into formula (14), can obtain tri-phase iron core remanent magnetism is formula (15);Because three-phase system has symmetry, therefore disconnected phase time headed by B, C phase, first mutually disconnected and another two-phase flux change rule is identical with above-mentioned situation, can obtain first disconnected phase remanent magnetism expression formula accordingly, shown in (16);Normal when running the advanced first disconnected Xiang Weici of 120 ° mutually of voltage-phase to break phase, this phase remanent magnetism is for shown in formula (17)Normal when running the voltage-phase delayed head Xiang Weimo of 120 ° mutually that breaks to break phase, this phase remanent magnetism is for shown in formula (18)φ md＝φ msin(δ-90°) (18)。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410723535.1A CN104483639B (en) | 2014-12-02 | 2014-12-02 | Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410723535.1A CN104483639B (en) | 2014-12-02 | 2014-12-02 | Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104483639A true CN104483639A (en) | 2015-04-01 |
| CN104483639B CN104483639B (en) | 2017-02-22 |
Family
ID=52758204
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410723535.1A Active CN104483639B (en) | 2014-12-02 | 2014-12-02 | Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104483639B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104833928A (en) * | 2015-04-30 | 2015-08-12 | 国网四川省电力公司电力科学研究院 | Large-scale power transformer residual magnetism detection method |
| CN106019186A (en) * | 2016-06-03 | 2016-10-12 | 国网河北省电力公司电力科学研究院 | Transformer core residual magnetism detection method based on no-load current method |
| CN107302216A (en) * | 2017-07-18 | 2017-10-27 | 西安交通大学 | YNd11 types three-phase transformer drops excitation surge current suppressing method |
| CN107947115A (en) * | 2017-12-14 | 2018-04-20 | 中南大学 | Monitoring is with suppressing transformer DC magnetic bias system in a kind of AT tractive power supply systems |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5963029A (en) * | 1996-01-30 | 1999-10-05 | Seagate Technology, Inc. | Measuring magnetic properties in media by RMS signal processing and incremental erasure |
| US6201386B1 (en) * | 1997-04-23 | 2001-03-13 | Redcliffe Magtronics Limited | Method for demagnetizing and measuring remanence and coercivity characteristics of a magnetic sample |
| CN102645640A (en) * | 2012-04-25 | 2012-08-22 | 云南电力试验研究院（集团）有限公司电力研究院 | Method for measuring ferromagnetic element residual magnetic flux by using direct current method |
| CN103913710A (en) * | 2014-03-28 | 2014-07-09 | 云南电力试验研究院（集团）有限公司电力研究院 | Method for measuring residual magnetic flux density of iron core of transformer |
-
2014
- 2014-12-02 CN CN201410723535.1A patent/CN104483639B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5963029A (en) * | 1996-01-30 | 1999-10-05 | Seagate Technology, Inc. | Measuring magnetic properties in media by RMS signal processing and incremental erasure |
| US6201386B1 (en) * | 1997-04-23 | 2001-03-13 | Redcliffe Magtronics Limited | Method for demagnetizing and measuring remanence and coercivity characteristics of a magnetic sample |
| CN102645640A (en) * | 2012-04-25 | 2012-08-22 | 云南电力试验研究院（集团）有限公司电力研究院 | Method for measuring ferromagnetic element residual magnetic flux by using direct current method |
| CN103913710A (en) * | 2014-03-28 | 2014-07-09 | 云南电力试验研究院（集团）有限公司电力研究院 | Method for measuring residual magnetic flux density of iron core of transformer |
Non-Patent Citations (3)
| Title |
|---|
| 周建平 等: "变压器铁心剩磁的一种估算方法", 《热力发电》 * |
| 邢运民 等: "变压器铁心剩磁估量", 《电网技术》 * |
| 邹晓峰 等: "三相不同期合闸下变压器电磁暂态分析及对保护的影响", 《电力系统自动化》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104833928A (en) * | 2015-04-30 | 2015-08-12 | 国网四川省电力公司电力科学研究院 | Large-scale power transformer residual magnetism detection method |
| CN104833928B (en) * | 2015-04-30 | 2017-09-29 | 国网四川省电力公司电力科学研究院 | A kind of large-scale power transformer remanent magnetism detection method |
| CN106019186A (en) * | 2016-06-03 | 2016-10-12 | 国网河北省电力公司电力科学研究院 | Transformer core residual magnetism detection method based on no-load current method |
| CN106019186B (en) * | 2016-06-03 | 2019-11-05 | 国网河北省电力公司电力科学研究院 | A kind of transformer core remanent magnetism detection method based on no-load current method |
| CN107302216A (en) * | 2017-07-18 | 2017-10-27 | 西安交通大学 | YNd11 types three-phase transformer drops excitation surge current suppressing method |
| CN107947115A (en) * | 2017-12-14 | 2018-04-20 | 中南大学 | Monitoring is with suppressing transformer DC magnetic bias system in a kind of AT tractive power supply systems |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104483639B (en) | 2017-02-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103986385B (en) | Method for restraining no-load closing magnetizing inrush current of transformer | |
| CN103474981B (en) | A kind of distribution network single-phase ground protection method based on the multistage differential transformation direction of zero-sequence current | |
| CN107302216B (en) | YNd11 type three-phase transformers drop excitation surge current suppressing method | |
| CN106526474B (en) | Load switch zero crossing operation test system and method for electric energy meter | |
| Brenna et al. | Petersen coil regulators analysis using a real-time digital simulator | |
| CN104483639A (en) | Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer | |
| Rezaei-Zare et al. | An accurate current transformer model based on Preisach theory for the analysis of electromagnetic transients | |
| CN109001592A (en) | A kind of resonant earthed system fault line selection method for single-phase-to-ground fault based on transient | |
| Corrodi et al. | Influence of system transients on the residual flux of an unloaded transformer | |
| CN102879671A (en) | Method for judging inrush current locking of equivalent instantaneous inductance for protection of extra-high voltage regulating transformer | |
| CN107482600B (en) | Yyn0 type three-phase group formula transformer drops excitation surge current suppressing method | |
| CN104459578A (en) | Residual magnetism estimation method for Yyn0-type three-phase combined transformer non-fault tripping | |
| CN104459579A (en) | Residual magnetism estimation method for Dyn11-type three-phase combined transformer non-fault tripping | |
| Li et al. | Harmonic distortion feature of AC transformers caused by DC bias | |
| CN108333540B (en) | Method and system for evaluating residual magnetism of current transformer for metering | |
| Lu et al. | The effects of the current transformer saturation on mal-operation under the DC magnetic bias caused by HVDC | |
| Tishuai et al. | Influence of system transients on the residual flux of three-phase transformers | |
| CN107332212B (en) | The three-phase group formula transformer excitation flow suppressing method to close a floodgate from delta windings side | |
| CN108599104A (en) | Tranformer protection New Algorithm for Inrush Current Identification of Transformer | |
| CN108767826A (en) | Do not demagnetize converter power transformer air-drop excitation surge current suppressing method after straight resistance experiment | |
| Zubić et al. | Managing post-fault oscillation phenomenon in compensated MV-networks | |
| Jie et al. | Analysis of Magnetizing Inrush Current of Yy10 Transformer Based on RTDS | |
| Cai et al. | Simulation Analysis of Ferromagnetic Resonance of 10kV Electromagnetic Voltage Transformer | |
| Guan et al. | Novel power transformer differential protection scheme based on improved short-window algorithm | |
| CN104360157B (en) | Transformer interval breaker closing phase detection method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |