DETAILED ACTION
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 .
Claims 1 and 6-12 are pending in this application.
Information Disclosure Statement
The information disclosure statement (IDS) were submitted on 01/13/2025 and 01/13/2026. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Claim Objections
Claim 1 objected to because of the following informalities:
Claim 1, “a modular multilevel power convertor” should be -- a modular multilevel power converter--.
Appropriate correction is required.
Claim Rejections - 35 USC § 102
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 (i.e., changing from AIA to pre-AIA ) 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.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1 and 7 are rejected under 35 U.S.C. 102(a)(1) and 102(a)(2) as being anticipated by Tahata (US 20220263424 A1).
Regarding claim 1, Tahata teaches an electric power conversion system (abstract, A power conversion system) comprising:
a self-commutated power converter (i.e. self-excited power converter 2, figs.1-2, 4-18) to perform power conversion between a three-phase alternating-current system and a direct-current system ([0033], self-excited power converter 2 to perform power conversion between DC system 14 and AC system 12);
a first transformer (i.e. transformer 13, figs.1-2, 4-18) having a primary side connected to the alternating-current system and a secondary side connected to the self-commutated power converter, the secondary side having a Y-connection ([0033], Power converter 2 and transformer 13 are connected to each other via an AC line 64) (also refer to figs.1-2, 4-18); and
an impedance switching circuit (i.e. impedance circuit 41, figs.1, 4-14) electrically connected between a neutral point of the Y- connection of the first transformer and a ground ([0036], impedance circuit 41 is connected between neutral point 62 on the secondary side of transformer 13 and the ground),
wherein when a single-line-to-ground fault occurs on three phase alternating-current lines connecting the first transformer and the self-commutated power converter, the impedance switching circuit is configured to have a reduced impedance, as compared to when the single- line-to-ground fault does not occur ([0037], a fault current flowing through the ground upon occurrence of a ground fault on the DC side (for example, DC power transmission lines 14P and 14N) or on the AC side (for example, AC line 64) of power converter 2 is reduced by impedance circuit 41),
wherein the impedance switching circuit includes a magnetic inductor configured of a core reactor electrically connected between the neutral point and the ground ([0068], iron-core reactor 44 as impedance circuit 41 is connected between neutral point 62 on the secondary side of transformer 13 and the ground) (also refer to figs.5-7) or a second transformer including a primary winding or a secondary winding electrically connected between the neutral point and the ground ([0080], a potential transformer 47 as impedance circuit 41 is connected between neutral point 62 on the secondary side of transformer 13 and the ground) (figs.8-12), and
when a voltage, generated at the neutral point upon occurrence of the single-line- to-ground fault ([0069], upon occurrence of a ground fault on the AC side or the DC side of power converter 2), is applied to the magnetic inductor, the magnetic inductor is configured to cause magnetic saturation ([0073], prevent a fault current from becoming excessive due to saturation) (it is necessarily true the inductor gets saturated), and when a voltage, generated at the neutral point when the single-line-to- ground fault does not occur, is applied to the magnetic inductor, the magnetic inductor is configured to cause no magnetic saturation (it is necessarily true that no fault results in no voltage change at magnetic inductor and hence no saturation),
wherein the impedance switching circuit further includes a current-limiting resistor connected in series to the magnetic inductor between the neutral point and the ground ([0075], impedance circuit 41 is configured of a series circuit in which iron-core reactor 44 and a resistance 46 are connected in series),
wherein the self-commutated power converter is a modular multilevel power convertor ([0040], power conversion device 1 is configured of an MMC converter) including a plurality of sub modules ([0040], including a plurality of sub-modules (corresponding to “SM” in FIG. 2) 7) which are electrically connected in series ([0040], connected in series to each other) between a direct-current power distribution line of a direct-current system and each phase of the three phase alternating- current lines (e.g. between AC system 12 and DC system 14, fig.2),
the plurality of sub modules each include a direct-current capacitor ([0052], Power storage element 32 is configured mainly using a film capacitor),
upon occurrence of the single-line-to-ground fault, a voltage difference between the direct-current power distribution line and an alternating-current line of a sound phase at which a ground fault does not occur, among the three phase alternating-current lines, increases with an increase of an electrical resistance value of the current-limiting resistor ([0076], the fault current can be reduced by resistance 46), and the electrical resistance value is set to a maximum value within a range ([0077], resistance value of resistance 46 needs to be set to the level at which the effect of fixing the DC potential to ground of power converter 2 is ensured), achieving the voltage difference preventing the direct-current capacitor of each of the plurality of sub modules from experiencing overvoltage upon occurrence of a single-line-to-ground fault (it is necessarily true that the capacitor is protected from overvoltage, as any fault is grounded via impedance switching circuit).
Regarding claim 7, Tahata substantially teaches the claim limitations as stated above for claim 1. Tahata further teaches, a detector to detect occurrence of the single-line-to-ground fault ([0119], When a fault occurs on the AC side or the DC side of power converter 2 (or upon arrival of the maintenance timing of power converter 2), controller 3 stops the operation of power converter 2), wherein the impedance switching circuit includes a switch connected between the neutral point and the ground (i.e. switch 61, fig.14), and the switch is kept off in a time period in which occurrence of the single-line-to-ground fault is not detected by the detector, and turns on upon detection of occurrence of the single- line-to-ground fault by the detector ([0130], when each switch 61 is closed and each phase of AC line 64 is grounded via impedance circuit 41).
Claims 10-11 are rejected under 35 U.S.C. 102(a)(1) and 102(a)(2) as being anticipated by Sun (CN 104753079 A).
Regarding claim 10, Sun teaches an electric power conversion system (abstract, voltage source type inverter mixed direct current power transmission system), comprising:
a self-commutated power converter (page 5, twelve-pulse bridge thyristor converter L5) to perform power conversion between a three-phase alternating-current system and a direct-current system (page 6, converted three-phase alternating current voltage into direct current);
a transformer connected between the alternating-current system and the self- commutated power converter (e.g. transformer L4, fig.1);
three phase alternating-current lines connecting between the transformer and the self- commutated power converter (page 5, current source converter the AC system side L1), and
a filter circuit connected between the ground and each of a first direct-current transmission line and a second direct-current transmission line (e.g. DC capacitor Y7, fig.1), the first direct-current transmission line and the second direct-current transmission line constituting the direct-current system (page 6, DC capacitor Y7 is connected between the direct current bus of a voltage source type inverter), wherein the filter circuit is configured to pass a system frequency component of the alternating- current system (page 6, used to maintain a stable DC voltage, equivalent to the balancing node of the direct current system) (it is necessarily true that the DC capacitor passes certain frequency component).
Regarding claim 11, Sun teaches the electric power conversion system according to claim 10, wherein the filter circuit is configured to have frequency characteristics that block a component of a frequency, other than the system frequency of the alternating-current system (page 7, the fixed direct current voltage mode operation, namely direct current capacitor Y7 voltage remains unchanged).
Claim Rejections - 35 USC § 103
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 (i.e., changing from AIA to pre-AIA ) 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.
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, 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.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Tahata (US 20220263424 A1), and further in view of Priebe (US 20210313799 A1).
Regarding claim 6, Tahata substantially teaches the claim limitations as stated above for claim 1.
Tahata does not teach, wherein the impedance switching circuit includes a lightning arrestor connected between the neutral point and the ground, and a turn-on voltage for the lightning arrestor is lower than a voltage that develops at the neutral point upon occurrence of the single-line-to-ground fault, and higher than a voltage that develops at the neutral point when the single-line-to-ground fault does not occur.
Priebe teaches in a similar field of endeavor of transformer star point grounding for overvoltage, a lightning arrestor (i.e. second overvoltage-limiting component 205, first overvoltage-limiting component 26, fig.2) connected between the neutral point and the ground (e.g. connected between 23 and 17, fig.2), and a turn-on voltage for the lightning arrestor is lower than a voltage that develops at the neutral point upon occurrence of the single-line-to-ground fault, and higher than a voltage that develops at the neutral point when the single-line-to-ground fault does not occur ([0051], in the event of a fault, in the electrical potential of the star point 23 being reduced).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included the impedance switching circuit includes a lightning arrestor connected between the neutral point and the ground, and a turn-on voltage for the lightning arrestor is lower than a voltage that develops at the neutral point upon occurrence of the single-line-to-ground fault, and higher than a voltage that develops at the neutral point when the single-line-to-ground fault does not occur in Tahata, as taught by Priebe, as it provides the advantage of limiting the current and voltage fluctuations arising in the event of a fault.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Tahata (US 20220263424 A1), and further in view of Yang (CN 107154619 B).
Regarding claim 8, Tahata substantially teaches the claim limitations as stated above for claim 1.
Tahata does not teach, wherein the impedance switching circuit includes an air gap formed between the neutral point and the ground, and the air gap is configured to cause flashover when applied a voltage developed at the neutral point upon occurrence of the single-line-to-ground fault, and cause no flashover when applied a voltage developed at the neutral point when the single-line-to-ground fault does not occur.
Yang teaches in a similar field of endeavor of automatic switching for grounding fault, an air gap formed between the neutral point and the ground (i.e. gap grounding structure 3, fig.3), and the air gap is configured to cause flashover when applied a voltage developed at the neutral point upon occurrence of the single-line-to-ground fault, and cause no flashover when applied a voltage developed at the neutral point when the single-line-to-ground fault does not occur (page 5, The gap grounding structure 3 and the direct grounding structure 4 belong to a large current grounding system, which is directly grounded through the neutral point, when the single-phase grounding fault occurs).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included an air gap formed between the neutral point and the ground, and the air gap is configured to cause flashover when applied a voltage developed at the neutral point upon occurrence of the single-line-to-ground fault, and cause no flashover when applied a voltage developed at the neutral point when the single-line-to-ground fault does not occur in Tahata, as taught by Yang, as it provides the advantage of flexibility in design and grounding system for large currents.
Claims 9 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Tahata (US 20220263424 A1) and Priebe (US 20210313799 A1), and further in view of Sun (CN 104753079 A).
Regarding claim 9, Tahata and Priebe teach the electric power conversion system according to claim 6.
Tahata and Priebe do not teach, further comprising: a filter circuit connected between the ground and each of a first direct-current transmission line and a second direct-current transmission line, the first direct-current transmission line and the second direct-current transmission line constituting the direct-current system, wherein the filter circuit is configured to pass a system frequency component of the alternating- current system.
Sun substantially teaches the claim limitations as stated above in claim 10.
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have optionally included a filter circuit connected between the ground and each of a first direct-current transmission line and a second direct-current transmission line, the first direct-current transmission line and the second direct-current transmission line constituting the direct-current system, wherein the filter circuit is configured to pass a system frequency component of the alternating- current system in Tahata and Priebe, as taught by Sun, as it provides the advantage of removing noise and further stabilizing the DC power.
Regarding claim 12, it is rejected for the same reasons as stated above for claim 11.
Conclusion
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/SREEYA SREEVATSA/ Primary Examiner, Art Unit 2838 08/27/2026
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