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公开(公告)号：US20240250518A1
公开(公告)日：2024-07-25
申请号：US18419092
申请日：2024-01-22
CPC分类号： H02H7/045 , H02H1/0007 , H02H7/042
摘要： A system for high-impedance differential protection for power systems using a variety of signals from the power system. A fault may be detected using filtered phase current or filtered phase voltage magnitudes from current transformers (CTs) connected in parallel by phase. A fault may be detected using filtered phase voltages and raw phase voltages from the CTs. A fault may be detected using raw phase currents and raw phase voltages from the CTs. A fault may be detected using filtered phase currents and raw phase currents. A fault may be detected using raw phase currents and raw neutral currents. The embodiments herein maintain dependability and security of a differential element even when low-class CTs are used. The embodiments herein may allow users to optimize pickup settings even when low-class CTs are used.
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2.发明授权公开(公告)号：US11984720B2
公开(公告)日：2024-05-14
申请号：US17100412
申请日：2020-11-20
申请人： TechHold, LLC
摘要： A protection circuit is disclosed. The protection circuit includes a direct current (DC) blocking component electrically connected between a neutral of the transformer and a ground, and an overvoltage protection device electrically connected in parallel with the DC blocking component. The overvoltage protection device is constructed to repeatably and reliably provide overvoltage protection in response to a voltage at the transformer neutral above a threshold. The DC blocking component has an impedance below a predetermined value, thereby effectively grounding the neutral of the transformer. The DC blocking component is persistently maintained in connection to the transformer neutral.
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公开(公告)号：US20220271527A1
公开(公告)日：2022-08-25
申请号：US17677879
申请日：2022-02-22
申请人： S&C Electric Company
摘要： A system and method for determining when an electronic interrupting device will open in response to detecting overcurrent, where the interrupting device protects a transformer in a power distribution network. The method includes obtaining a time/current through fault protection curve that is defined by a plurality of time/current points for the transformer that identifies when the transformer may experience thermal or mechanical damage in response to a certain current flow over a certain time in the transformer windings, selecting a time multiplier, and determining an operating curve for the interrupting device by multiplying the multiplier and a time portion of each of the plurality of time/current points on the through fault protection curve, where the operating curve identifies when the interrupting device will open in response to a certain current flow over a certain time.
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公开(公告)号：US11411390B2
公开(公告)日：2022-08-09
申请号：US17139393
申请日：2020-12-31
摘要： Detection of, and protection against faults within a restricted earth fault (REF) zone of a transformer or a generator is disclosed herein. Security of the REF protection element uses comparison of a negative-sequence reference quantity. The REF condition is only detected when there is sufficient ground involvement and a fault in the reverse detection has not been detected. Dependability of the REF protection element in low-impedance grounded systems is improved by ensuring that the element operates when a zero-sequence reference quantity and a neutral operate quantity are orthogonal to each other. The REF protection element further determines an open CT condition and blocks detection of an REF fault upon determination of the open CT condition. A tripping subsystem may issue a trip command based upon detection of the REF condition.
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公开(公告)号：US10578653B2
公开(公告)日：2020-03-03
申请号：US15910226
申请日：2018-03-02
发明人： Ritwik Chowdhury , Dale S. Finney
摘要： Disclosed are systems and methods to determine an overexcitation condition on electric power delivery system equipment that includes a magnetizing core. Overexcitation conditions are determined even during sub-synchronous resonance, ferro-resonance, and other complex events. Power system voltage is integrated and normalized to determine a flux on the magnetizing core. The flux is compared with a protection model to determine the overexcitation condition on the magnetizing core. Once an overexcitation condition is detected, a protective action may be taken to remove power from the effected power delivery system equipment.
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6.发明申请公开(公告)号：US20180261999A1
公开(公告)日：2018-09-13
申请号：US15462913
申请日：2017-03-20
申请人： NXP USA, INC.
发明人： CHANGHAO SHI , RUI LV , DECHANG WANG
CPC分类号： H02H7/042 , G01R31/027 , H02H3/20 , H02H7/045
摘要： An apparatus for detecting disconnection of a secondary side of a current transformer includes a sampling circuit coupled to the secondary side of the current transformer that samples signals from the secondary side of the current transformer. A pull-up circuit is switchably coupled to the sampling circuit in response to a coupling signal in a diagnostic phase. A processor is coupled to the sampling circuit for receiving sampled signals from the sampling circuit. The processor extracts corresponding signal information from the sampled signals and stores the extracted signal information in a memory. The extracted signal information corresponds to statuses that the secondary side of the current transformer is connected or disconnected to a load. A detector is coupled to the processor and the memory, and accesses the memory using the signal information of the sampled signals.
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公开(公告)号：US09899830B2
公开(公告)日：2018-02-20
申请号：US14770240
申请日：2013-04-07
申请人： ABB Schweiz AG
发明人： Youyi Li , Kai Liu , Ivo Brncic , Zhanpeng Shi
摘要： The present invention discloses a method for detecting a fault and a current differential protection system thereof. The method for detecting fault includes calculating fault component currents, calculating an operate current and a restraint current of all terminals, and adjusting an operate level by adapting an operate-restraint characteristic according to a fault component. The method has very small operating area for external faults, which makes the method very reliable even for the case with serious CT saturation. A very big operating area for internal faults makes the method very sensitive for internal faults even for a heavy load and high resistance fault.
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公开(公告)号：US09891289B2
公开(公告)日：2018-02-13
申请号：US14727956
申请日：2015-06-02
发明人： Ljubomir A. Kojovic
CPC分类号： G01R31/40 , G01R15/181 , G01R19/10 , G01R19/16504 , H02H3/28 , H02H7/045
摘要： Techniques for detecting an inrush current in a power transformer in are disclosed. For example, the presence of an inrush current on a current path in a power transformer may be determined by receiving a signal from a Rogowski coil positioned on a current path of a power transformer, the signal corresponding to a current flowing in the current path; sampling the received signal to produce samples of the received signal; and analyzing the samples of the received signal relative to at least two criteria to determine whether an inrush current is present. When an inrush current is present, operation of a protective relay is blocked.
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9.发明申请公开(公告)号：US20170331279A1
公开(公告)日：2017-11-16
申请号：US15526802
申请日：2014-11-14
发明人： FRANK MIESKE
CPC分类号： H02H7/0455 , G01R19/165 , G01R31/025 , H02H3/30 , H02H7/045 , H02H7/065 , H02J3/00
摘要： A differential protection method for generating a fault signal includes measuring current measurements at least at two different measuring points of a multiphase transformer for each phase. The current measurements for each phase are used to form differential current values and stabilization values. The fault signal is generated if it is determined during a trigger region check that a measurement pair of at least one of the phases, being formed by using one of the differential current values and the associated stabilization value in each case, is in a predefined trigger region. In order to be able to selectively and reliably distinguish an external fault from an internal fault, the transformer has a grounded star point and a zero system current flowing through the star point is used to form the stabilization values. A corresponding differential protection device is provided for performing the differential protection method.
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公开(公告)号：US09640981B2
公开(公告)日：2017-05-02
申请号：US14426873
申请日：2013-07-01
发明人： Jun Chen , Quanrong Shen , Wei Yan , Huimin Wang , Kai Wang , Huazhong Li
CPC分类号： H02H7/045
摘要： A frequency-conversion differential protection method for an output transformer of a static frequency convertor system. The method comprises: a protection device measuring a three-phase current at each side of an output transformer of an SFC system; according to the connection manner of the output transformer, using a triangle side as a reference to conduct phase correction on a star side; at the same time, taking into account different secondary rated currents at each side of the transformer to adjust a balance coefficient of each side, so as to form sampling values of a correcting current and a differential current at each side, and using a startup and shut-down protection algorithm free from frequency influence in generator protection to calculate amplitude values of the correcting current, the differential current and a restraint current; and according to the magnitudes of the differential current and the restraint current, using the ratio restraint differential characteristic to achieve the frequency-conversion ratio differential protection of the output transformer. The present protection method is suitable for large-scale frequency change. Compared with the current quick-breaking protection, the sensitivity of internal failure detection in the output transformer is greatly improved.
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