Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 12/09/2025. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Response to Arguments
Applicant’s arguments/amendment, see page 8, filed 03/13/2026, with respect to USC 112 and 101 rejections of claim 12 and 16 respectively have been fully considered and are persuasive. The rejection USC 112 and 101 rejections of claim 12 and 16 respectively has been withdrawn.
Applicant's arguments filed 03/13/2026 with respect to USC 103 rejections of claims 1-20 have been fully considered but they are not persuasive.
Applicant argues that Guzman-Casillas fails to disclose "determining at least one phase angle between the voltages at the first position and the estimated voltages at the second position," because Guzman-Casillas determines angle differences between sending-end and receiving-end generators rather than estimating voltages at a second position of a power line.
Applicant further argues that Liu fails to remedy this alleged deficiency because Liu does not expressly disclose determining a phase angle between voltages at first and second positions.
The Examiner respectfully disagrees because the arguments improperly attack the references individually, whereas the rejection is based upon the combined teachings of Guzman-Casillas and Liu. Non obviousness cannot be established by attacking references individually where the rejection is predicated upon a combination of prior art references. See In re Merck, 800 F.2d 1091, 1097 (Fed. Cir. 1986).
Further, Applicant's attempt to distinguish generator locations from positions on a transmission line is not commensurate with the scope of the claims. The claims broadly recite "first position" and "second position" and do not positively exclude sending-end and receiving end locations within the transmission system.
As set forth in the rejection, Guzman-Casillas teaches obtaining voltage measurements from different locations in a power transmission system and determining angle differences between those locations using synchronized voltage measurements. See Guzman-Casillas, [0052-55]. Accordingly, Guzman-Casillas teaches determining phase-angle differences between voltages associated with different positions in the power system.
As further set forth in the rejection, Liu teaches determining or estimating a voltage at a setting point on an electrical line from measured voltage and current values obtained at another measurement point using a line model. See Liu [0007-10] and Fig. 1. Liu therefore teaches the claimed estimated voltage at the second position.
Applicant's argument that Liu is silent regarding determining a phase angle is likewise unpersuasive because the rejection does not rely on Liu alone for this teaching. Rather, Guzman-Casillas teaches determining phase-angle differences, while Liu teaches estimating
voltages at another line position. The rejection relies on the combined teachings of the references.
Accordingly, the combination of Guzman-Casillas and Liu teaches or at least suggests: obtaining voltages at a first position, estimating voltages at a second position of the power line, and, determining a phase angle between voltages associated with different positions of the power line.
Further, once Liu determines a voltage at the setting point, determining a corresponding phase-angle relationship between voltages would have been within the level of ordinary skill in the art. Therefore, the combination of Guzman-Casillas and Liu collectively teaches or renders obvious the disputed limitations of claim 1.
Applicant has not persuasively shown reversible error in the rejection. Applicant does not present separate substantive arguments for dependent claims 2-20. Therefore, claims 2-20 stand or fall with claim 1. Accordingly, the rejection of claims 1-20 under 35 U.S.C. §103 is maintained.
Claim Rejections - 35 USC § 103
6. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Guzman-Casillas (U.S. Publication 20090089608) in view of Liu (U.S. Publication 20190004103).
Regarding claim 1, Guzman-Casillas teaches method of determining a fault of a power system (detecting faults and out of step OOS conditions in electrical power systems [0017, 0049]), comprising:, the measured electrical quantities being associated with three phases of the power system and comprising voltages at the first position of the power line (“Systems and methods for calculating a positive sequence voltage given a three-phase voltage measurement” [0017, 0050-0052]); determining at least one phase angle between the voltages at the first position (determining the phase angle difference between two system locations using their voltage phasors [0052-55]); and detecting the fault based on the at least one phase angle during a power swing (detecting out of step and fault conditions including during power swings using the calculated phase angle, slip frequency and acceleration [0048-55 describing how angle based parameters discriminate between stable, unstable swings and fault conditions]).
However, Liu teaching system and apparatus for fault detection in line protection for a power transmission system teaches estimating, based on measured electrical quantities at a first position of a power line in the power system, voltages at a second position of the power line (determining a voltage at a setting point (a second location on the line) using only local volage, current and differential value of current obtained at a measurement point (the first position) fig. 1 [0007-0011] describes obtaining voltage, current at measurement point, determine di/dt, computing the voltage at the remote settling point according to a time domain lumped parameter model), and the estimated voltages at the second position (obtaining an estimated remote (second) voltage “he voltage change between the determined voltage at the setting point during the fault period and a voltage at the setting point determined during the pre-fault time period can be further determined. The fault detection can be performed based on the determined voltage change and a fault threshold,.., the determining a voltage at a setting point may be performed based on a differential equation….”[0007-0011]).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the estimated remote end voltage teaching of Liu in Guzman’s measured remote end voltage, since Guzman merely required that a remote voltage phasor be available for angle difference calculation and Liu provides a known and compatible technique for deriving the remote voltage from locally measured electrical quantities , thereby supplying the exact voltage input needed by Guzman’s angle based fault and swing detection to gain advantage of improving reliability and speed by eliminating dependence on remote communication and ensuring continuous availability of the remote end voltage during system disturbances such as power swings.
Regarding claims 2, 17, Guzman-Casillas as modified further teaches determining a first phase angle between the phase voltage of a first phase at the first position and the estimated phase voltage of the first phase at the second position; and determining a second phase angle between the interphase voltage of a second phase to a third phase at the first position and the estimated interphase voltage of the second phase to the third phase at the second position (computing phase angles using positive sequence, phase-phase and phase natural voltage phasor, thus determining phase angles “determine the angle difference .delta. between sending-end and receiving-end generators and/or generator equivalents. The angle difference .delta. may be determined from voltage measurements obtained by IEDs at particular locations in the power system (e.g., at the sending-end and receiving-end of the power system). In some embodiments, positive sequence voltages and/or alpha-Clarke components may be derived from the voltage measurements. Systems and methods for calculating a positive sequence voltage given a three-phase voltage measurement are well known in the art. An alpha-Clarke component of such a voltage measurement may be calculated per equation….” [0052-55]).
Regarding claims 3, 18, Guzman-Casillas as modified further teaches for each of the three phases, determining a phase angle between the phase voltage of the respective phase at the first position and the estimated phase voltage of the same phase at the second position (calculating angle differences using positive sequence, but also angle differences may be obtained from per phase voltages “a-Clarke components and three phase input” [0052]).
Regarding claims 4, 19, Guzman-Casillas as modified further teaches for each of three two-phase combinations, determining a phase angle between the interphase voltage of the respective two-phase combination at the first position and the estimated interphase voltage of the same two-phase combination at the second position (using line-line interphase voltages for angle calculation [0038] a-clarke transformation rely on interphase relationship [0052-55]).
Regarding claims 5, 20, Guzman-Casillas as modified further teaches for each of the three phases, determining a first phase angle between the phase voltage of the respective phase at the first position and the estimated phase voltage of the same phase at the second position; for each of three two-phase combinations, determining a second phase angle between the interphase voltage of the respective two-phase combination at the first position and the estimated interphase voltage of the same two-phase combination at the second position; and determining an average angle based on the first phase angles for the three phases and the second phase angles for the three two-phase combinations as the at least one phase angle (“The output of the CTA module 910 may comprise time aligned voltage measurements 914 and 924, which may flow to a characterization function module 920. The characterization function module 920 may derive an angle difference .delta., using the time aligned voltage measurements 914 and 924. Using the angle difference .delta., the characterization function module 920 may calculate a slip frequency S.sub.F, and acceleration A.sub.F. The angle difference .delta., slip frequency S.sub.F, and acceleration A.sub.F may be used to monitor the electrical power system as will be described below. This may comprise determining an operating point of the power system using the angle difference .delta., slip frequency S.sub.F, and/or acceleration A.sub.F. The operating point may be compared to one or more characteristics, such as predictive OOS characteristic or the like. An OOS condition may be detected if the operating point falls outside of the one or more operating characteristics” [0103] the use of aggregated or derived angle matrices such as slip frequency and acceleration which aggregate values derived from multiple instantaneous angle differences., producing an average across multiple phase angle measurement).
Regarding claim 6, Guzman-Casillas as modified further teaches determining a phase angle between a positive-sequence component of the phase voltage of one of the three phases at the first position and a positive-sequence component of the estimated phase voltage of the same phase at the second position (use of positive sequence voltage for angle difference computation “the positive-sequence voltages and/or alpha-Clarke components be estimated so that a first and second derivative of the angle difference .delta. may be calculated…”[0052-55]).
Regarding claim 7, Guzman-Casillas as modified further teaches determining a time threshold for each of the at least one phase angle, based on a measured duration of the respective phase angle previously falling within a predefined range, and determining the fault, in the event that a duration of any of the at least one phase angle within the predefined range exceeds the respective time threshold (the time based discrimination techniques using angle trajectories, including angle difference duration and slip frequency timing, these describe identifying unstable vs stable swings based on how long angle remains within a defined region [0048-55]).
Regarding claim 8, Guzman-Casillas as modified further teaches detecting the fault based on change rates of the at least one phase angle relative to time during a power swing (computing slip frequency and acceleration for swing detection “positive-sequence voltages and/or alpha-Clarke components be estimated so that a first and second derivative of the angle difference .delta. may be calculated” [0054-60]).
Regarding claim 9, Guzman-Casillas as modified further teaches determining the change rate of the respective phase angle relative to time; determining a time threshold for each of the at least one phase angle, based on the determined change rate and the predefined range; and determining the fault, in the event that a duration of any of the at least one phase angle within the predefined range exceeds the respective time threshold (“the power swing detection system 1000 may detect a power swing condition in a power system segment if the absolute value of the slip frequency is greater than 0.2 Hz, the absolute value of the acceleration is greater than 0.1 Hz/sec., and the local current satisfies a sensitivity threshold for a sufficient time period and/or number of clock cycles (depending on the configuration of security counters 1070, 1072, and 1074). As described above, these conditions may cause the PSD output 1082 to assert. The PSD output 1082 may de-assert if either: greater than 10 Hz or less than 0.2 Hz; greater than 50 Hz/sec or less than 0.1 Hz/sec.; or the sensitivity threshold (e.g., nominal current threshold) is not satisfied” [0130]).
Regarding claim 10, Guzman-Casillas as modified further teaches in response to the respective phase angle falling into the predefined range, determining an instantaneous change rate of the respective phase angle relative to time (instantaneous derivative values (slip frequency) “detects power swings by calculating an angle difference .delta. between a sending-end and a receiving-end of the power system. Using the angle difference .delta., a slip frequency S.sub.F, and acceleration A.sub.F may be calculated. These values may be derived from local and remote voltage measurements. The slip frequency S.sub.F frequency may be calculated per Equation 1.3” [0055]).
Regarding claim 11, Guzman-Casillas as modified further teaches wherein determining the change rate of the respective phase angle relative to time comprises: in response to the respective phase angle falling into the predefined range, determining an average change rate of the respective phase angle relative to time in a recent cycle of the power swing, wherein the recent cycle of the power swing comprises a time period from a time point previously entering the predefined range to a time point currently entering the predefined range (oscillatory swing behavior and implicitly operate over swing cycle “if a power swing is detected, a power swing detection indicator may be asserted. If an OOS condition is detected, additional actions may be taken at step 660 including, but not limited to, disconnecting the power system segment from the rest of the power network, taking protective actions to prevent damage to the power system apparatuses and network, and the like. It should be understood that upon detecting a particular power system condition an IED may programmatically respond in any number of ways. As such, this disclosure should not be read as limited to any particular protection and/or fault mitigation technique and/or methodology. The method then returns to step 610 to continue monitoring the power system” [0077]).
Regarding claim 12, Guzman-Casillas as modified further teaches for each of the at least one phase angle, in response to the respective phase angle falling into a predefined range comprising, determining an instantaneous change rate of the respective phase angle relative to time; and in response to the instantaneous change rate of any of the at least one phase angle exceeding a predefined threshold, determining the fault (using slip frequency compared to decision boundaries for detecting swing instability “detects power swings by calculating an angle difference .delta. between a sending-end and a receiving-end of the power system. Using the angle difference .delta., a slip frequency S.sub.F, and acceleration A.sub.F may be calculated. These values may be derived from local and remote voltage measurements. The slip frequency S.sub.F frequency may be calculated per Equation 1.3” [0055-60])).
Regarding claim 13, Guzman-Casillas does not explicitly teach calculating, based on the measured electrical quantities, the voltages at the second position of the power line in a time domain.
However, Liu teaching system and apparatus for fault detection in line protection for a power transmission system teaches calculating, based on the measured electrical quantities, the voltages at the second position of the power line in a time domain (time domain voltage determination using differential equations and lumped parameter line models [0007-11]).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the estimated remote end voltage teaching of Liu in Guzman’s measured remote end voltage, since Guzman merely required that a remote voltage phasor be available for angle difference calculation and Liu provides a known and compatible technique for deriving the remote voltage from locally measured electrical quantities , thereby supplying the exact voltage input needed by Guzman’s angle based fault and swing detection to gain advantage of improving reliability and speed by eliminating dependence on remote communication and ensuring continuous availability of the remote end voltage during system disturbances such as power swings.
Regarding claim 14, Guzman-Casillas as modified further teaches at least one processing unit; and at least one memory coupled to the at least one processing unit and storing instructions executable by the at least one processing unit, the instructions, when executed by the at least one processing unit, causing the device to perform the method according to claim 1
Regarding claim 15, Guzman-Casillas as modified further teaches wherein the electronic device comprises a distance relay used in a power system [0019].
Regarding claim 16, Guzman-Casillas as modified further teaches a computer readable storage medium having computer readable program instructions stored thereon which, when executed by a processing unit, cause the processing unit to perform the method according to claim 1. ([0171]).
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAQI R NASIR whose telephone number is (571)270-1425. The examiner can normally be reached 9AM-5PM EST M-F.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Lee Rodak can be reached at (571) 270-5628. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/TAQI R NASIR/Examiner, Art Unit 2858
/LEE E RODAK/Supervisory Patent Examiner, Art Unit 2858
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