WO2018009992A1 - Procédé de protection de transformateur contre les défaillances internes - Google Patents

Procédé de protection de transformateur contre les défaillances internes Download PDF

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Publication number
WO2018009992A1
WO2018009992A1 PCT/BR2017/000071 BR2017000071W WO2018009992A1 WO 2018009992 A1 WO2018009992 A1 WO 2018009992A1 BR 2017000071 W BR2017000071 W BR 2017000071W WO 2018009992 A1 WO2018009992 A1 WO 2018009992A1
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WO
WIPO (PCT)
Prior art keywords
sub
fault
faults
internal
transformer
Prior art date
Application number
PCT/BR2017/000071
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English (en)
Portuguese (pt)
Inventor
Fabiano Gustavo Silveira MAGRIN
Maria Cristina Dias Tavares
Original Assignee
Universidade Estadual De Campinas - Unicamp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Universidade Estadual De Campinas - Unicamp filed Critical Universidade Estadual De Campinas - Unicamp
Publication of WO2018009992A1 publication Critical patent/WO2018009992A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/72—Testing of electric windings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
    • H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers

Definitions

  • the present invention fits into the field of fault detection methodologies for a power transformer, wherein said methodology is applied with high sensitivity for transformer internal faults, between turns and ground, enabling the removal of the power transformer. service power quickly and reliably.
  • the present invention can be applied to fault detection in other equipment such as motors, shunt bumpers, capacitor banks and transmission lines, with transformers being considered the most critical case.
  • transformers must be serviced frequently, but even so, they are subject to short circuits, which is considered serious as there is always a risk of fire.
  • damage to the equipment occurs that needs to be repaired. However, it is in reducing the extent of damage that protective equipment works. The faster the abnormality is detected, the less damage to the equipment.
  • Document CN101702512 presents a proposal directed only to generators. First a calculation of. minimum current of I.2 .. When it is above 10% of the load, the zero sequence impedance angle is compared to certain limits. If between Degrees and 90 degrees the fault is external, and if between -90 degrees and -180 degrees, the fault is internal.
  • the possibilities offered by this invention are only restricted to generators, unlike the present invention, which. extends its field of application through inventive and differentiated technology, which will be detailed below.
  • US5514978 is based on the negative sequence impedance calculation. The method makes several accounts, compares 22 with a limit, but. do inverse accounts, read 12, and, after multiplying by Z2, compare. With a threshold of V2 perpetratDo the opposite too, reads V2 ⁇ compares with a 12 after calculation with a standard impedance 22.
  • the technology disclosed in US5514978 is exclusively motor-related, while the present invention broadens its scope by of inventive and differentiated technology.
  • US781.2615 the operating principle distinguished from the present invention. It is mentioned that US7812615 technology can identify 23 ⁇ 4 faults between turns. However, some technical problems can be identified, such as: having a low current sensor. negative sequence; use a minimum negative sequence differential current and use the angle to discriminate the fault, it is not clear how to use the method for more than two currents. In this regard, it is noteworthy that, in a differential manner, the present invention has a very accurate sensitivity, less than 1% for faults between turns.
  • US517Q308 discloses a technology based on the calculation of parallel transformer admittance. It applies to the detection of internal faults during power-up, which is not proposed by the present invention.
  • Document CN10: 4991160 describes a technology for detecting transformer internal faults. For its operation, a capacitive coupling sensor must be installed. This equipment injects high frequency which is measured and treated for detection.
  • the present invention differs from CN1Q4991160 mainly in that it uses a different operating principle based on negative sequence impedances.
  • the CN104991I60 requires the installation of extra equipment in the transformer, unlike the present invention, which still has the advantage of using only existing equipment for measurement, characterizing its adaptability and portability.
  • the present invention allows to present greater and improved sensitivity in detecting internal faults in power transformers. Said invention is not subject to the transformer energizing current or even the over-excitation of the power transformer. State of the art methods based on negative sequence current apply a minimum current comparator for executing an algorithm and the present invention does not, contributing to the increased sensitivity of the element. Another differential is that in no other work is it mentioned that after an external fault is output, there is a transient in the negative sequence diagram and that this transient resembles an internal fault, requiring a block or appropriate desensitization of the algorithm. A further advantage of the present invention is still the ease of expansion of the method for equipment with more than two inputs / outputs.
  • the present invention relates to a transformer protection method for internal faults.
  • the method disclosed in the present invention aims to increase the sensitivity of detection of internal faults in equipment, mainly power transformers, but may also be employed in the detection of internal faults in other equipment such as motors, generators, shunt reactors, capacitor bank, transmission lines and even for the combination of more than one equipment in the protection zone.
  • the present method acts by increasing a. sensitivity to internal faults, thereby shortening operating times and promoting a reduction in equipment damage under the protection it provides.
  • FIGURE 1 shows the example power system.
  • FIGURE 2 graphically shows the negative sequence impedances seen by the delta side:
  • FIGURE 3 graphically shows the negative sequence impedances seen by the star side.
  • FIGURE 4 graphically shows the negative sequence impedances seen by the delta side.
  • FIGURE 5 graphically shows the negative sequence impedances seen by the star side.
  • FIGURE € graphically shows negative sequence impedances., Delta side,
  • FIGURE 7 graphically shows the negative sequence impedances, debut side.
  • FIGURE 8 shows the sequence diagram for single-phase fault in bar R.
  • FIGURE 9 presents a sequence diagram for single-phase fault in S-bar.
  • FIGURE 10 represents a. impedance view seen from both sides of the trafo.
  • FIGURE. 11 is a graphical presentation of the action plan referenced in the present invention.
  • FIGURE 12 is a graphical presentation of misconduct for external fault.
  • FIGURE 13 is a graphical presentation of the new plan of action.
  • FIGURE 1.4 is a sequence diagram for external two-phase fault.
  • FIGURE 15 shows the negative sequence impedance excursion.
  • the present invention relates to a transformer protection method for internal faults which comprises the following steps and substeps:
  • cl Calculates the derivatives of the voltages of each terminal in relation to the past (from 1 to 3 cycles); c2) Compare sub-step (cl) with threshold L1 (from 0.01 to 5);
  • c.6 Declares internal disturbance if one of the derivatives of sub-step (c.2) is true and sub-step (c.4) is false by time t2 (from 0 to 3 cycles); c7) Declare internal disturbance if more than one derivative of sub-step (c.3) is true and (c.4) is false by time t3 (from 0 to .3 cycles);
  • the method disclosed in the present invention aims to increase fault detection sensitivity internal equipment, mainly in power transformers, but can also be used to detect internal faults in other equipment such as motors, generators, shunt reactors, capacitor banks, transmission lines and even for the combination of more than one equipment. in the protection zone.
  • the present method is not intended to replace the transformer's main protection scheme, but to supplement it by increasing the sensitivity to internal faults, thereby reducing actuation times and promoting a reduction in damage to equipment under protection, particularly in the case of of transformers ..
  • This method measures all: currents entering or leaving the equipment under protection. Also measures all voltages around the protected equipment. These currents and voltages are filtered through analog and digital filters in order to extract the fundamental components. Having the fundamental component factors, negative sequence currents, voltages, and impedances are calculated. Negative sequence impedances are compared to an impedance plane to detect if the fault is internal to the transformer. When all impedances fall within the specified plane, the fault is internal. In case of external fault, and after its elimination, there is a transient in the negative sequence diagram that can cause negative sequence dependent elements to act. To avoid this kind of misconduct, this kind of phenomenon should be identified and the blocking or desensitization of the method execution should be promoted.
  • Fault analysis comprises the study and recognition of how electrical quantities behave for transformer internal faults. External faults are also analyzed to find out what differentiates them from internal faults, enabling the development of the method of the present invention which is disclosed herein.
  • Figures 4 and 5 show the negative sequence impedance behavior for inter-loop faults. It is observed that the behavior of impedances is the same as in the case of ground faults.
  • Figure 8 shows the sequence diagram for a single phase fault on the R bar, ie on the star side of the transformer. It can be observed that the positive sequence and negative sequence current of source S are the same transformer currents, both on the delta side and the star side, only with the reversal of direction. For zero sequence current, there is no current on the delta side and there is current on the transformer neutral and the star side.
  • the negative sequence impedance measured by the delta side for an external fault on the R bar will have the value of the source impedance S with a negative value.
  • the impedance measured by the star side for the same fault will have the value of the sum of the impedances of the source S and the transformer, with positive value.
  • Figure 10 summarizes the negative sequence impedance view for both sides. It turns out that only for. transformer internal faults both sides may see a negative impedance.
  • Impedances on both sides determine whether the sources are strong or weak, so these impedances can range from zero to infinity. Thus it is determined that zero and minus infinity are points of action and, consequently, the region of operation, as shown in Figure 11.
  • This element is referred to here as negative impedance for internal faults or negative impedance for internal fault, Z2IF.
  • FIG. 14 shows the sequence diagram for. the two-phase transformer external fault on the R-bar and rewriting the negative sequence impedance equations for each side of the transformer have:
  • Figure 15 shows the method response in the presence of an internal loop fault with 1% of the shorted star winding. It is possible to verify the negative sequence impedance excursion to the permanent state of the impedances when the fault is present.
  • Figure 16 complements the analysis showing the currents of. both sides of the transformer and the operation bit of the method described herein.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
  • Protection Of Transformers (AREA)

Abstract

La présente invention concerne un procédé de protection de transformateur contre les défaillances internes. En résumé, le procédé de l'invention vise à augmenter la sensibilité de détection de défaillances internes dans des équipements, notamment des transformateurs de puissance, mais peut également être utilisé dans la détection de défaillances internes dans d'autres équipements, tels que des moteurs, des générateurs, des réacteurs shunt, un banc de condensateurs, des lignes de transmission, voire la combinaison de plusieurs équipements dans la zone de protection. Le présent procédé permet d'augmenter la sensibilité aux défaillances internes, réduisant ainsi les temps d'actionnement et favorisant une réduction de l'endommagement des équipements auxquels cette protection est fournie.
PCT/BR2017/000071 2016-07-12 2017-07-07 Procédé de protection de transformateur contre les défaillances internes WO2018009992A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BR102016016171-1A BR102016016171A2 (pt) 2016-07-12 2016-07-12 Método de proteção de transformador para faltas internas
BRBR1020160161711 2016-07-12

Publications (1)

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WO2018009992A1 true WO2018009992A1 (fr) 2018-01-18

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110460104A (zh) * 2019-09-20 2019-11-15 南京南瑞继保电气有限公司 一种光伏逆变器等效正、负序故障阻抗推导方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080130179A1 (en) * 2003-12-31 2008-06-05 Abb Ab Method And Device For Fault Detection In Transformers Or Power Lines
US20090091867A1 (en) * 2007-10-09 2009-04-09 Armando Guzman-Casillas Transformer Through-Fault Current Monitor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080130179A1 (en) * 2003-12-31 2008-06-05 Abb Ab Method And Device For Fault Detection In Transformers Or Power Lines
US20090091867A1 (en) * 2007-10-09 2009-04-09 Armando Guzman-Casillas Transformer Through-Fault Current Monitor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110460104A (zh) * 2019-09-20 2019-11-15 南京南瑞继保电气有限公司 一种光伏逆变器等效正、负序故障阻抗推导方法

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