WO2008138873A1 - Broadband detecting circuit - Google Patents
Broadband detecting circuit Download PDFInfo
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- WO2008138873A1 WO2008138873A1 PCT/EP2008/055721 EP2008055721W WO2008138873A1 WO 2008138873 A1 WO2008138873 A1 WO 2008138873A1 EP 2008055721 W EP2008055721 W EP 2008055721W WO 2008138873 A1 WO2008138873 A1 WO 2008138873A1
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- WO
- WIPO (PCT)
- Prior art keywords
- impedance
- current
- detection circuit
- sensing
- differential
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/02—Transmitters
- H04B1/04—Circuits
- H04B1/0458—Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Transmitters (AREA)
Abstract
The present invention relates to a detection circuit, transmitter front-end module, and detection method, wherein an input current of an impedance is routed through a primary winding of a transformer arrangement (30; 32, 34). A short circuit current of a secondary winding of the transformer arrangement is sensed to measure the input current of the impedance.
Description
Broadband detecting circuit
FIELD OF THE INVENTION
The present invention relates to a circuit, transmitter module, and method of for detecting an impedance.
BACKGROUND OF THE INVENTION
In general, the overall performance of a radio frequency (RF) power amplifier (PA) can be optimized by suitably choosing its load impedance. However, due to environmental influences the impedance at the driven load (e.g. antenna) is not constant and can put the RF PA in a non-optimal operating condition. This causes performance degradation of the RF PA in power efficiency, output power and linearity.
To solve this problem it has been suggested to place an isolator or circulator between the power amplifier and the load (e.g. antenna) . The properties of such an isolator are such that the signal can only propagate in one direction and that any reflected power is absorbed in a load that is connected to a third terminal of the device. Thus, the impedance mismatch of the antenna does not affect the performance of the power amplifier anymore. However, an isolator is big, expensive, and power inefficient. Moreover, it is not suitable for use in low cost, low power, portable communication systems.
As explained for example in WO2006/038167A1 a way to solve the above antenna mismatch problem is by sensing the RF load impedance and dynamically correcting a matching network provided between the load (e.g. antenna) and the RF PA.
I. Yokoshima, "RF Impedance Measurements by Voltage-Current Detection," IEEE Trans. Instrumentation and Meas . , vol. 42, no. 2, April 1993 discloses a method of sensing an RF impedance by using V/I detection. The RF voltage and current
are sensed through a resistor and a pick-up coil, respectively. Using this method, the RF current is measured indirectly by sensing the voltage across a reference impedance, which is connected to the pick-up coil (secondary winding) . Due to non-idealities of a practical transformer, this method introduces a phase shift and a frequency dependency in the voltage read-out due to the self-inductance of the transformer windings, which makes the detection non- trivial. Furthermore, the current and voltage are measured across a resistive impedance, which means that some RF power is absorbed, and thus this sensing method is not loss-less.
The WO2006/038167A1 discloses a method of current sensing, wherein the voltage difference across an impedance is measured by using a differential amplifier. Also this method introduces frequency dependency and phase shift in the voltage read-out when the impedance is reactive. On the other hand, a series sensing resistor (which introduces no phase shift) is undesirable, since it introduces additional losses in the path between the antenna and the PA. Making the resistor very small is not a feasible solution, since it sets tremendous requirements on the common mode rejection ratio (CMMR) of the differential voltage amplifier.
A further method of sensing the complex impedance is described in D. Qiao, et al, "Antenna Impedance Mismatch Measurements and Correction for Adaptive CDMA Transceivers," IEEE MTT-S Digest, pp. 783-786, June 2005. Using this method, the impedance can be determined by measuring two independent voltage ratios, i.e. the voltages at three different points on the transmission line. For this method, knowledge is needed of the characteristic impedance of the line. This method requires three measurements along a transmission line, which has a relatively long length (quarter wavelength) and is not really suitable for integration. One could think of making a lumped equivalent of this transmission line, but this technique still remains a narrow-band solution. Moreover, knowledge is needed about the value of the lumped components, making the measurement procedure non-trivial.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a detection method and circuit, which enable broadband and loss-less current sensing.
This object is achieved by a detection circuit as claimed in claim 1, and by a detection method as claimed in claim 13.
Accordingly, by measuring or detecting the current in this way, a frequency-independent and loss-less current read-out can be established. The proposed circuit can directly sense the short-circuit current through a pick-up coil by using the transimpedance amplifier. Using this method, no CMRR requirement exists on the current detector as in conventional circuits and no frequency dependency is introduced, since magnetic coupling factor between the pick-up coil and the transmission line can be assumed constant. Although the use of transimpedance amplifiers may add to total DC-power consumption, the signal power supplied to the impedance is not compromised.
In an exemplary implementation, the detection circuit may be adapted to detect an impedance, wherein the detection circuit may further comprise another transimpedance amplifier for measuring a voltage at said impedance via a sensing impedance. Thereby, an impedance sensor can be provided, which does not suffer from bandwidth limitations and does not introduce additional losses in the signal path in which the impedance is sensed. The proposed detection circuit can be designed in such a way that it does not disturb or loads the sensing node itself. The outputs of the transimpedance amplifiers can be fed into any kind of impedance detector circuit. Another possibility is to sample the outputs of the transimpedance amplifiers, which could lower the total power consumption of the proposed sensor/detector circuit. This is possible since the impedance changes relatively slowly (e.g. for adaptive antenna matching or the like) , so that the impedance could be measured at relatively large intervals.
In another exemplary implementation, the detection circuit may comprise a differential circuit, wherein the transformer arrangement may comprise a first primary winding, through which a first differential component of the current is caused to flow, and a second primary winding, through which a second differential component of the current is caused to flow, and wherein the transformer arrangement may comprise a first secondary winding, grounded at one end and connected to a first differential input of the transimpedance amplifier, and a second secondary winding, grounded at one end and connected to a second differential input of the transimpedance amplifier. Such a differential implementation provides better rejection of external noise or interference and is especially of interest for detection of currents of at differential amplifiers or the like.
In a further exemplary implementation, the differential circuit may be arranged to detect an impedance, wherein first and second differential components of a voltage at the impedance may be applied to respective first and second differential inputs of another transimpedance amplifier via a sensing impedance. Thus, the proposed solution can be used for differential impedance measurements in connection with impedance matching purposes.
In the above exemplary implementations, the sensing impedance may comprise a sensing capacitor and the other transimpedance amplifier may comprise at least one voltage-to-current feedback capacitor. Thereby, sensing amplification can be controlled by suitable selection of the capacitance ratio between the sensing capacitor and the feedback capacitor. Moreover, the capacitor-based implementation allows incorporation of sensing capacitor (s) into the design of transmission lines.
Alternatively, in the above implementations, the sensing impedance may comprise a sensing resistor and the other transimpedance amplifier may comprise a voltage-to-current feedback resistor. Sensing amplification can now be controlled
by suitable selection of the resistance ratio between the sensing resistor and the feedback resistor.
According to another exemplary implementation, the transformer arrangement may be implemented by coupled transmission lines which have a small electrical length with respect to an operation wavelength of the circuit. As an example, the coupled transmission lines may be configured as lumped coupled inductors. In this or another example, the circuit may be configured in a manner so that all parasitic and sensing capacitors are connected in parallel to ground or to virtual ground of the first and second transimpedance amplifiers. In the above or other examples, the circuit may be configured as an L-type matching network in an impedance transformation network between an amplifier and a load. Such a design can thus be easily incorporated as part of existing impedance matching network (s) and will thus not add any additional chip or circuit area due to additional passive components apart from the sensing electronics needed to process the sampled voltage and current signals.
Further advantageous embodiments are defined in the dependent claims .
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the present invention will be described in greater detail based on embodiments with reference to the accompanying drawings in which:
Fig. 1 shows a general schematic circuit diagram of a working principle of the proposed detection circuit;
Fig. 2 shows a schematic circuit diagram of a detection circuit according to a first embodiment;
Fig. 3 shows schematic circuit diagram of a detection circuit according to a second embodiment;
Fig. 4 shows a schematic circuit diagram of a detection circuit according to a third embodiment; and
Fig. 5 shows a practical embodiment of a detection circuit according to the second embodiment using a lumped capacitor and coupled transmission line.
DESCRIPTION OF THE EMBODIMENT
The embodiments of the present invention will now be described in greater detail based on a broadband complex RF impedance detector based on voltage/current (V/I) sensing. It is however noted that the present invention is not restricted to such a specific implementation and could as well be used in any kind of current ant/or voltage detection for any purpose.
In the following embodiment, a broadband and loss-less voltage and current sensor or detection circuit is proposed, which can be used e.g. for detecting an impedance.
Fig. 1 shows a general and principle structure of the proposed detection circuit for RF impedance detection by measuring voltage vin and current I1n between an output of a power amplifier (PA) 10 and a load ZL (e.g. antenna load) directly via an impedance Z3 and a transformer 30, respectively.
The input voltage vin is sensed by or via the impedance Z3 and amplified using a first transimpedance amplifier 22. The input current I1n is sensed by measuring the short circuit current in the secondary winding L3 of the transformer 30 and amplified using a second transimpedance amplifier 24. By measuring the current in this way, a frequency-independent and loss-less current read-out can be established. It is noted that the use of the first and second transimpedance amplifiers 22, 24 will add to the total DC-power consumption, but the RF signal power from the PA 10 to the load ZL is not compromised.
A transimpedance amplifier may be implemented based on an operational amplifier which has a very high "inherent" gain.
However, if a feedback resistor (or impedance) is connected to it, i.e., from the output to the input and some input current is supplied into the input (also known as the summing point) , the gain is so high that all of the current must flow through the feedback resistor and the output voltage will be VOuτ = -(IIN x RF) • Such an amplifier circuit is then called a "current-to-voltage converter" or "transimpedance amplifier, " where the "gain" or "transimpedance" is equal to the feedback resistor .
In Fig. 1, the outputs vv and V1 of the first and second transimpedance amplifiers 22 and 24 can be fed into an analogue complex impedance detector circuit such as described for example in the WO2006/038167, where the peak voltage, peak current, and phase difference between the measured voltage and current are determined. Of course other known impedance detector circuits could be used as well. Another possibility is to sample the outputs vv and V1, which could lower the total power consumption of the overall sensor/detector circuit. This is possible since the impedance changes relatively slowly (for adaptive antenna matching) and could therefore be measured at relatively large intervals (e.g. 1 s) .
Fig. 2 shows a schematic circuit diagram of the first embodiment of the voltage and current sensor for RF impedance measurements .
The input voltage V1n is sensed using a sensing capacitor Cs and is amplified through a first transimpedance amplifier 22 having a voltage-to-current feedback capacitor CF. The input current I1n is sensed through the secondary winding L3 of a transformer 30, which is grounded at one side. The secondary measurement current is amplified through a second transimpedance amplifier 24 having a voltage-to-current feedback resistor RF.
Fig. 3 shows a schematic circuit diagram of the second embodiment of the voltage and current sensor for RF impedance measurements, where the input voltage vin is sensed using a
sensing resistor R3 and amplified through a first transimpedance amplifier 22 having a voltage-to-current feedback resistor RF. Additionally, input current sensing is implemented as shown in Fig. 2.
For the above first and second embodiments input voltage sensing can be expressed by:
V C V R (ϊ) F m s
The current sensing can be expressed by
[I)
where n = km I—- , and km is the magnetic coupling coefficient, which are tnes main non-idealities of the transformer 30. It proves that both embodiments are broadband solutions, when assuming ideal (broadband) transimpedance amplifiers 22, 24.
Fig. 4 shows a schematic circuit diagram of a detection circuit according to a third embodiment which is a differential implementation of the voltage and current detection circuit, which is especially interesting for differential PA or front-end module (FEM) implementations. Differential components vin+ and vin- of the differential voltage are measured by connecting the two differential inputs "+" and "-" of a first differential transimpedance amplifier 26 via respective sensing capacitors CS to respective lines of the differential transmission line between the differential PA 12 and a symmetrizing or balancing, respectively, transformer 36. The symmetrizing transformer 36 enables connection of the grounded load ZL to the differential transmission line. Furthermore, a differential transformer arrangement comprising a first transformer 32 and a second transformer 34 is provided, wherein one end of both secondary windings LS is connected to ground. The other end of the secondary windings LS is connected a respective one of the two differential
inputs "+" and "-" of a second differential transimpedance amplifier 28 having respective feedback resistors RF. The respective primary windings of the first and second transformers 32, 34 are connected into the respective lines of the differential transmission line in order to measure differential components iin+ and iin- of the differential input current to the load ZL.
In the third embodiment, the transformer arrangement can be implemented by two coupled transmission lines, which have a small electrical length with respect to the wavelength (typically < l/10λ) . This allows to model the coupled transmission lines as two lumped coupled inductors.
Fig. 5 shows a practical embodiment of a detection circuit according to the second embodiment using a lumped capacitor and coupled transmission lines MLl and ML2 (left-hand side) and its equivalent schematic circuit (right-hand side) .
A closer look to the equivalent circuit in Fig. 5 reveals that the voltage and current sensing network can be designed in such a way that there is minimum disturbance (undesired loading) at a point A of an upper main transmission line MLl due the impedance read-out. This is because in theory all parasitic capacitances CPl and CP2 and the sensing capacitor
CS are all connected in parallel to ground (due to the virtual ground of the transimpedance amplifiers) and can be incorporated in the design of the upper transmission line MLl. Moreover, as an example, the sensing network could even be incorporated as an L-section in a total impedance transformation network from the load ZL (e.g. antenna) to the PA 10, since the upper transmission line MLl (i.e. primary winding LP) and the capacitor parallel circuit CS//CP1//CP2 form an L-type matching network. For this reason, the circuit of the second embodiment shown in Fig. 2 is especially suitable for this implementation.
The above embodiments can be used for example in hand-held mobile phones, especially with the trend towards multi-mode
and multi-band PA front-end modules, where broadband sensing and correcting the load impedance is required (load-line adaptation) . Another interesting area is that of the so-called "picoradio", for instance used in low-power wireless sensor networks. Since these sensors are highly influenced by their environment, antenna impedance mismatch could well be a problem. Therefore, detection and correction of the RF load impedance is desirable in these applications.
In summary, a circuit, transmitter front-end module, and method of sensing an impedance have been described, wherein an input current of an impedance is routed through a primary winding of a transformer arrangement. A short circuit current of a secondary winding of the transformer arrangement is sensed to measure the input current of the impedance.
However, in general, the present invention is not restricted to the above embodiments or application examples and can be implemented in any discrete circuit arrangement or integrated architecture. The proposed current and voltage detection according to the first to third embodiments can be applied in any transmitter, transceiver, receiver system or even other systems (architectures) which requires broadband and/or lossless detection. The above embodiments may thus vary within the scope of the attached claims.
Finally, it is noted that the term "comprises" or "comprising" when used in the specification including the claims is intended to specify the presence of stated features, means, steps or components, but does not exclude the presence or addition of one or more other features, means, steps, components or group thereof. Further, the word "a" or "an" preceding an element in a claim does not exclude the presence of a plurality of such elements. Moreover, any reference sign does not limit the scope of the claims.
Claims
1. A detection circuit comprising: a) a transformer arrangement (30; 32, 34) having a primary winding through which current to be measured is caused to flow; and b) transimpedance amplifier (24; 28) for measuring a short circuit current of a secondary winding of said transformer arrangement so as to detect said current.
2. The detection circuit according to claim 1, wherein said detection circuit is adapted to detect an impedance, and wherein said detection circuit further comprises another transimpedance amplifier (26; 28) for measuring a voltage at said impedance via a sensing impedance.
3. The detection circuit according to claim 1, wherein said detection circuit comprises a differential circuit, wherein said transformer arrangement comprises a first primary winding, through which a first differential component of said current is caused to flow, and a second primary winding, through which a second differential component of said current is caused to flow, and wherein said transformer arrangement comprises a first secondary winding, grounded at one end and connected to a first differential input of said transimpedance amplifier (28), and a second secondary winding, grounded at one end and connected to a second differential input of said transimpedance amplifier (28) .
4. The detection circuit according to claim 3, wherein said differential circuit is arranged to detect an impedance, and wherein first and second differential components of a voltage at said impedance are applied to respective first and second differential inputs of another transimpedance amplifier (26) via a sensing impedance.
5. The detection circuit according to claim 2 or 4, wherein said sensing impedance comprises a sensing capacitor (Cs) and said other transimpedance amplifier comprises at least one voltage-to-current feedback capacitor (CF) .
6. The detection circuit according to claim 2 or 4, wherein said sensing impedance comprises a sensing resistor (R3) and said other transimpedance amplifier comprises a voltage-to-current feedback resistor (RF) .
7. The detection circuit according to any one of the preceding claims, wherein said transformer arrangement is implemented by coupled transmission lines which have a small electrical length with respect to an operation wavelength of said circuit.
8. The detection circuit according to claim 7, wherein said coupled transmission lines are configured as lumped coupled inductors .
9. The detection circuit according to claim 7 or 8, wherein said circuit is arranged so that all parasitic and sensing capacitors are connected in parallel to ground or to virtual ground of the transimpedance amplifiers (22, 24; 26, 28) .
10. The detection circuit according to any one of the preceding claims, wherein said circuit is configured as an L-type matching network in an impedance transformation network between an amplifier and a load.
11. A transmitter front-end module comprising a detection circuit according to any one of claims 1 to 10.
12. A transmitter front-end module according to claim 11, wherein said circuit is arranged between a power amplifier (10) and an antenna.
13. A detection method comprising: a) routing a current to be measured through a primary winding of a transformer arrangement (30; 32, 34); and b) measuring a short circuit current of a secondary winding of said transformer arrangement by a transimpedance amplifier so as to detect said current.
14. The detection method according to claim 13, wherein said detection method is used for detecting an impedance and further comprises measuring a voltage at said impedance by a transimpedance amplifier via a sensing impedance.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP07107826.5 | 2007-05-09 | ||
| EP07107826 | 2007-05-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2008138873A1 true WO2008138873A1 (en) | 2008-11-20 |
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ID=39637651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2008/055721 WO2008138873A1 (en) | 2007-05-09 | 2008-05-08 | Broadband detecting circuit |
Country Status (1)
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|---|---|
| WO (1) | WO2008138873A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2199733A1 (en) * | 2008-12-17 | 2010-06-23 | Mitutoyo Corporation | Electric circuit and method of operating a measuring instrument |
| US8345260B2 (en) | 2008-09-16 | 2013-01-01 | Mitutoyo Corporation | Method of detecting a movement of a measuring probe and measuring instrument |
| US8606376B2 (en) | 2009-01-14 | 2013-12-10 | Mitutoyo Corporation | Method of actuating a system, apparatus for modifying a control signal for actuation of a system and method of tuning such an apparatus |
| CN105425041A (en) * | 2015-09-21 | 2016-03-23 | 国家电网公司 | Calculating method of impedance value of three-winding transformer based on short circuit current restraint |
| CN105939011A (en) * | 2016-03-22 | 2016-09-14 | 江苏省电力公司电力经济技术研究院 | Optimization method of impedance values of three-winding transformer of substation |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3815013A (en) * | 1972-06-14 | 1974-06-04 | Gen Electric | Current transformer with active load termination |
| EP0071560A1 (en) * | 1981-07-24 | 1983-02-09 | Siemens Aktiengesellschaft | High-voltage measuring arrangement with capacitive dividers mounted in a vessel filled with insulating gas |
| US4659981A (en) * | 1985-09-24 | 1987-04-21 | Sony Corporation | Input transformer circuit |
| DE29714612U1 (en) * | 1996-08-19 | 1997-10-23 | Siemens Ag | Current measuring device |
| FR2813123A1 (en) * | 2000-08-18 | 2002-02-22 | Ercom Engineering Reseaux Comm | Probe for observing and analyzing asymmetric and symmetric junctions in telephone networks where a signal is produced that mirrors the signal carried in the junction so that it can be observed using the usual operating equipment |
| GB2388914A (en) * | 2002-05-10 | 2003-11-26 | Pri Ltd | Current transformer with reduced resistance |
| WO2006038167A1 (en) * | 2004-10-06 | 2006-04-13 | Koninklijke Philips Electronics N.V. | Impedance detector |
| WO2006054245A1 (en) * | 2004-11-19 | 2006-05-26 | Koninklijke Philips Electronics N.V. | Device comprising a load line coupled to an output of an amplifier stage |
| WO2006054246A1 (en) * | 2004-11-19 | 2006-05-26 | Koninklijke Philips Electronics N.V. | Device comprising a controlled matching stage |
-
2008
- 2008-05-08 WO PCT/EP2008/055721 patent/WO2008138873A1/en active Application Filing
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3815013A (en) * | 1972-06-14 | 1974-06-04 | Gen Electric | Current transformer with active load termination |
| EP0071560A1 (en) * | 1981-07-24 | 1983-02-09 | Siemens Aktiengesellschaft | High-voltage measuring arrangement with capacitive dividers mounted in a vessel filled with insulating gas |
| US4659981A (en) * | 1985-09-24 | 1987-04-21 | Sony Corporation | Input transformer circuit |
| DE29714612U1 (en) * | 1996-08-19 | 1997-10-23 | Siemens Ag | Current measuring device |
| FR2813123A1 (en) * | 2000-08-18 | 2002-02-22 | Ercom Engineering Reseaux Comm | Probe for observing and analyzing asymmetric and symmetric junctions in telephone networks where a signal is produced that mirrors the signal carried in the junction so that it can be observed using the usual operating equipment |
| GB2388914A (en) * | 2002-05-10 | 2003-11-26 | Pri Ltd | Current transformer with reduced resistance |
| WO2006038167A1 (en) * | 2004-10-06 | 2006-04-13 | Koninklijke Philips Electronics N.V. | Impedance detector |
| WO2006054245A1 (en) * | 2004-11-19 | 2006-05-26 | Koninklijke Philips Electronics N.V. | Device comprising a load line coupled to an output of an amplifier stage |
| WO2006054246A1 (en) * | 2004-11-19 | 2006-05-26 | Koninklijke Philips Electronics N.V. | Device comprising a controlled matching stage |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8345260B2 (en) | 2008-09-16 | 2013-01-01 | Mitutoyo Corporation | Method of detecting a movement of a measuring probe and measuring instrument |
| EP2199733A1 (en) * | 2008-12-17 | 2010-06-23 | Mitutoyo Corporation | Electric circuit and method of operating a measuring instrument |
| US8606376B2 (en) | 2009-01-14 | 2013-12-10 | Mitutoyo Corporation | Method of actuating a system, apparatus for modifying a control signal for actuation of a system and method of tuning such an apparatus |
| CN105425041A (en) * | 2015-09-21 | 2016-03-23 | 国家电网公司 | Calculating method of impedance value of three-winding transformer based on short circuit current restraint |
| CN105939011A (en) * | 2016-03-22 | 2016-09-14 | 江苏省电力公司电力经济技术研究院 | Optimization method of impedance values of three-winding transformer of substation |
| CN105939011B (en) * | 2016-03-22 | 2018-10-26 | 江苏省电力公司电力经济技术研究院 | A kind of optimization method of substation's three-winding transformer impedance value |
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