CN111413640A - Differential protection wiring detection method and device of high-impedance transformer - Google Patents
Differential protection wiring detection method and device of high-impedance transformer Download PDFInfo
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Abstract
The invention belongs to the field of differential protection wiring detection, and provides a differential protection wiring detection method and a differential protection wiring detection device of a high-impedance transformer. The method comprises the steps that a preset voltage is applied to a medium-voltage side of a high-impedance transformer, and a measured value of a secondary current of the medium-voltage side, a measured value of a secondary current of a high-voltage side and a measured value of a secondary current of the low-voltage side are obtained through measurement under the experimental condition that the high-voltage side and the low-voltage side are short-circuited; obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer; comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
Description
Technical Field
The invention belongs to the field of differential protection wiring detection, and particularly relates to a differential protection wiring detection method and device of a high-impedance transformer.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The high-impedance transformer refers to a transformer with the percentage of short-circuit voltage exceeding the percentage value specified by national standard of the same voltage class and the same capacity. There are two schemes for implementing a high impedance transformer: firstly, the medium-voltage side winding is split into two parts to increase the leakage reactance of the winding; and secondly, the leakage reactance of the winding is increased by connecting the lead in series with the reactor at the tail end of the low-voltage winding of the transformer. Background of the applications for high impedance transformers are: with the rapid expansion of the grid size, the short circuit capacity increases dramatically, leading to the occurrence of short circuit current levels exceeding the breaker break capacity. Compared with the conventional transformer, the high-impedance transformer has the advantage that the short-circuit impedance (which is composed of the winding resistance and the leakage impedance and can be characterized by the short-circuit voltage percentage) is larger, so that the positive sequence impedance of the system is increased, and the short-circuit current is limited.
The method is characterized in that a primary current and a working voltage are required to be checked and judged before a newly installed device or an equipment loop is put into operation according to the clear requirements of D L/T995-2006 relay protection and power grid safety automatic device inspection regulations, and the method is specifically realized by measuring the phases of current transformers of current differential protection groups and the differential current or differential voltage in a differential loop to judge the wiring correctness of the differential loop.
The inventor finds that for a starting transformer with impedance much higher than that of a system transformer, the short-circuit impedance of the medium-low voltage side is very high, and within a limited analog power output voltage range, the effective reading of a CT secondary circuit signal with high transformation ratio and low resolution is small, and in addition, the zero position of the system, data change is not obvious, the persuasion of a test result is low, and even misjudgment can be generated. Boosting and improving the capacity of a test power supply are the most direct ways to solve the problem of a CT secondary signal loop, but a series of problems of transportation, loading and unloading of equipment, safety of field application and the like are generated at the same time, and great inconvenience is brought to analog load check differential protection.
Disclosure of Invention
In order to solve the above problems, the present invention provides a differential protection wiring detection method for a high impedance transformer, which can effectively increase the primary current amplitudes of the high voltage side, the medium voltage side and the low voltage side under the experimental condition that a preset voltage is applied to the medium voltage side of the high impedance transformer and the high voltage side and the low voltage side are short-circuited, thereby achieving the purpose of increasing the secondary current signal amplitude.
In order to achieve the purpose, the invention adopts the following technical scheme:
a differential protection wiring detection method of a high-impedance transformer comprises the following steps:
applying a preset voltage on the medium-voltage side of the high-impedance transformer, and measuring to obtain a medium-voltage side secondary current measured value, a high-voltage side secondary current measured value and a low-voltage side secondary current measured value under the experimental condition that the high-voltage side and the low-voltage side are short-circuited;
obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer;
comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
In order to solve the above problem, a second aspect of the present invention provides a differential protection wiring detection device for a high impedance transformer, which is capable of effectively increasing the primary current amplitudes of the high voltage side, the medium voltage side and the low voltage side under the experimental condition that a preset voltage is applied to the medium voltage side of the high impedance transformer and the high voltage side and the low voltage side are short-circuited, so as to achieve the purpose of increasing the secondary current signal amplitude.
In order to achieve the purpose, the invention adopts the following technical scheme:
a differential protection wiring detection device of a high impedance transformer comprises:
a voltage applying power source for applying a preset voltage to a medium voltage side of the high impedance transformer;
the ammeter is used for measuring a secondary current measured value of the medium-voltage side, a secondary current measured value of the high-voltage side and a secondary current measured value of the low-voltage side under the experimental condition that a preset voltage is applied to the medium-voltage side of the high-impedance transformer and the high-voltage side and the low-voltage side are short-circuited;
a data processor for: obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer;
comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
The invention has the beneficial effects that:
according to the invention, a preset voltage is applied to the medium-voltage side of the high-impedance transformer, and the primary current amplitudes of the high-voltage side, the medium-voltage side and the low-voltage side are increased by times by effectively utilizing the power supply capacity under the condition that the high-voltage side and the low-voltage side are short-circuited, so that the purpose of increasing the secondary current signal amplitude is achieved; the high-voltage boosting of the high-impedance transformer can be avoided, and the differential protection wiring detection safety of the high-impedance transformer is high.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Fig. 1 is a flowchart of a differential protection connection detection method for a high impedance transformer according to an embodiment of the present invention;
FIG. 2 shows nameplate parameters of an A-phase transformer of a Gansu Zhangye 750kV ultra-high voltage substation;
fig. 3 shows impedance parameters of a phase-A transformer of Gansu tension fluid 750kV ultra-high voltage substation.
Detailed Description
The invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only terms of relationships determined for convenience of describing structural relationships of the parts or elements of the present invention, and are not intended to refer to any parts or elements of the present invention, and are not to be construed as limiting the present invention.
In the present invention, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be determined according to specific situations by persons skilled in the relevant scientific or technical field, and are not to be construed as limiting the present invention.
As shown in fig. 1, the method for detecting the differential protection connection of the high impedance transformer of the present embodiment includes:
step 1: applying a preset voltage (such as 380V or other preset voltage values) to the medium-voltage side of the high-impedance transformer, and measuring to obtain a medium-voltage side secondary current measured value, a high-voltage side secondary current measured value and a low-voltage side secondary current measured value under the experimental condition that the high-voltage side and the low-voltage side are short-circuited;
step 2: obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer;
and step 3: comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
The high-impedance transformer of the embodiment adopts short circuit between the high-voltage side and the low-voltage side, and the original basis of the pressurization of the medium-voltage side is the impedance parameters of the transformer, including the rated capacity and the rated voltage of the transformer in three operation modes of high-medium voltage, high-low voltage and medium-low voltage, and including the impedance percentages of the high-medium voltage, high-low voltage and medium-low voltage main connection short circuit of the transformer.
The implementation process of differential protection wiring detection is described in detail with reference to specific examples as follows:
as shown in FIG. 2 and FIG. 3, according to the transformer with model number 0DFPS-700000/750, the rated capacity of the high voltage and the medium voltage are 700MVA, and the combination of the high, medium and low three-winding voltages is 765 ^ and/or greater than
/345/
The percentage of main connection of the/63 kV short circuit impedance, converted to high or medium voltage rated capacity, was 17.72%, 57.13%, 35.73%, respectively.
According to the main short-circuit impedance parameter, the ohm value of the short-circuit impedance under the power frequency is Z10U 2UK/SN；
Wherein U represents the transformer voltage, with the unit of kV and UKRepresenting the primary connection percentage, S, of the short-circuit impedance of the transformerNRepresenting the capacity of the transformer and the unit is KVA;
calculating the short circuit impedance parameter of the 750kV main transformer to calculate the impedance ohm value under the power frequency:
through the calculation of the equivalent impedance of the transformer in a short circuit mode, the equivalent impedance is minimum after the medium voltage side is pressurized, the high voltage side and the low voltage side are short-circuited, the medium voltage side is pressurized at 345kV at this time, and the equivalent impedance of the medium voltage side to the high voltage side is converted:
ZM-H＝49.38/(765/345)2＝10.04Ω
the high-voltage side and the low-voltage side are connected with equivalent impedance in parallel after short circuit:
ZM-H∥L＝10.04×20.25/(10.04+20.25)＝6.71Ω
a primary current at the medium voltage side after 380V is applied from the medium voltage side
IM1＝380/1.732/6.71＝32.69A
The middle-voltage side test current is distributed between high-voltage side current and low-voltage side current:
IH1＝380/1.732/10.04＝21.85A
IL1＝380/1.732/20.25＝10.83A
converting to primary short-circuit current generated at high and low voltage sides:
IH1＝IH1×UM/UH＝21.85×345/765＝9.85A
IL1＝IL1×UM/UL＝10.83×345/63＝59.31A
the transformation ratios of the high-voltage side secondary circuit, the medium-voltage side secondary circuit and the low-voltage side secondary circuit are 1/2500, 1/5000 and 1/6000 respectively, and the generated secondary currents are respectively
IH2＝21.85×1/2500＝0.008A
IM2＝32.69×1/5000＝0.006A
IL2＝59.31×1/6000＝0.009A
This embodiment is compared with the traditional high-pressure side pressurization, medium-pressure side and low-pressure side short circuit:
the high voltage side is pressurized, the medium voltage side and the low voltage side are short-circuited, and the generated primary current is IH1＝5.82A，IM1＝9.84A，IL1＝9.66A；
The transformation ratios of the high-voltage side secondary circuit, the medium-voltage side secondary circuit and the low-voltage side secondary circuit are 1/2500, 1/5000 and 1/6000 respectively, and the generated secondary currents are I respectivelyH2＝0.0023A，IM2＝0.0019A，IL2＝0.0016A。
Comparing the results of the medium-pressure side pressurization and the high-pressure side pressurization, the measured value of the high-pressure side is at the edge of resolution and can be completely covered by the zero position of the system, and the reading of the medium-pressure side pressurization is 3 to 4 times that of the high-pressure side, so that the phase difference and the transformation ratio information can be judged.
The method for testing differential protection wiring by adopting a short-circuit method for a high transformer, namely the test method for testing the short circuit between a high-voltage side and a low-voltage side by adopting medium-voltage side pressurization in the embodiment, comprises the following concrete implementation processes:
calculating the short-circuit impedance Z of high-to-medium voltageH-MAnd converted into the equivalent impedance Z of the medium-voltage side to the high-voltage sideM-H；
Calculating the short-circuit impedance Z of medium to low voltageM-L；
High voltage to low voltage short circuit impedance Z in this embodimentH-LHigh voltage to medium voltage short circuit impedance ZH-MAll according to the calculation formula of short-circuit impedance ohm value under power frequency, Z is 10U2*UK/SNObtaining;
in the embodiment, the medium-voltage to high-voltage conversion impedance is converted by multiplying the square of the ratio of the voltage levels of the high voltage and the medium voltage by the short-circuit impedance of the high voltage to the medium voltage;
calculating the equivalent impedance Z after the short circuit between the high-voltage side and the low-voltage sideM-H//L＝ZM-H*ZM-L/(ZM-H+ZM-L)；
The high-voltage side and the low-voltage side are simultaneously short-circuited in the embodiment, so that the equivalent impedance of the medium-voltage side is reduced, and the current amplitude of the medium-voltage side is improved;
applying three-phase balanced voltage U to medium voltage side1Typically 380V, calculating the primary current generated at the medium voltage side as IM1＝U1/ZM-H//L；
The purpose of applying 380V three-phase balanced voltage in the embodiment is that a three-phase power supply generally adopts a three-phase power supply input and a transformer substation entrance with better electric energy quality, 380V power output can be realized without a boosting device, and the equipment universality is strong.
It is understood that in other embodiments, other voltage values may be applied by the medium voltage side.
The test current of the medium-voltage side is distributed to the high-voltage side and the low-voltage side, and the distribution relation is as follows:
IH1＝U1*UM/UH*ZM-H；
IL1＝U1*UM/UL*ZM-L；
calculating to obtain a secondary signal amplitude I according to the primary current amplitude and the transformation ratio2＝I1/S；
According to the amplitude and phase relation of the secondary signals, a hexagonal relation graph is drawn, the original medium-pressure phase A is used as a reference and is converted into a high-pressure phase A which is used as a reference, and the hexagonal phase relation and the transformation ratio show effects which can be compared with the effects of high-pressure side pressurization. According to the embodiment, low-voltage side pressurization, medium-voltage side short circuit and high-voltage side short circuit are conceivable, the low-voltage side pressurization is feasible theoretically, but the low-voltage side pressurization, high-voltage side short circuit test scheme and the medium-voltage side short circuit test scheme require lower opening voltage and higher working current support, and the equipment weight and field operability are increased invisibly.
The test effect of the short circuit testing differential protection wiring method for the high-impedance transformer on the extra-high voltage high-capacity starting transformer is obvious, the effect is also obvious in the aspect of reducing zero deviation generated by a CT secondary measurement system on the starting transformer with lower impedance, and the method is also applicable to field application.
The technical scheme of the differential protection wiring detection device of the high impedance transformer in the embodiment is given below.
The differential protection wiring detection device of the high-impedance transformer comprises:
(1) a voltage applying power source for applying a preset voltage to a medium voltage side of the high impedance transformer;
(2) the ammeter is used for measuring a secondary current measured value of the medium-voltage side, a secondary current measured value of the high-voltage side and a secondary current measured value of the low-voltage side under the experimental condition that a preset voltage is applied to the medium-voltage side of the high-impedance transformer and the high-voltage side and the low-voltage side are short-circuited;
(3) a data processor for: obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer;
comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
The pressurization power supply is a simulation load through-flow pressurization test power supply.
In this embodiment, the simulated load through-flow pressurization test power supply can be provided with a hexagonal phase relation display diagram, and the actual transformer parameters are input to display the transformation ratio and polarity relation of the transformer, so that comparison and verification with field test results are facilitated.
Specifically, in the data processor, the calculation process of the calculated value of the secondary current on the medium-voltage side, the calculated value of the secondary current on the high-voltage side and the calculated value of the secondary current on the low-voltage side under the same experimental conditions is as follows:
obtaining a primary current of the medium-voltage side according to the voltage pressurized by the medium-voltage side of the high-impedance transformer and the parallel equivalent impedance after the medium-voltage side and the low-voltage side are short-circuited;
calculating the currents distributed on the high-voltage side and the low-voltage side according to the distribution relation of the primary current of the medium-voltage side to the high-voltage side and the low-voltage side, and converting the currents into primary short-circuit currents generated on the high-voltage side and the low-voltage side according to corresponding transformation ratios;
according to the transformation ratio of the medium-voltage side, the high-voltage side and the low-voltage side, the medium-voltage side primary current, the high-voltage side primary current and the low-voltage side primary current are converted into a medium-voltage side secondary current, a high-voltage side secondary current and a low-voltage side secondary current respectively.
In the present embodiment, the parallel equivalent impedance after the short circuit between the medium voltage side and the low voltage side is equal to the equivalent impedance between the medium voltage side and the high voltage side — the short circuit impedance between the medium voltage side and the low voltage/(the equivalent impedance between the medium voltage side and the high voltage side + the short circuit impedance between the medium voltage side and the low voltage). The short-circuit impedance of the high voltage to the medium voltage is converted according to the square of the ratio of the voltage levels of the high voltage to the medium voltage multiplied by the short-circuit impedance of the high voltage to the medium voltage.
In other embodiments, the data processor is further coupled to a display for displaying whether the differential protection connections of the high impedance transformer are properly made.
In this embodiment, the pressurizing power source is used to pressurize to 380V on the medium-voltage side of the high-impedance transformer.
The power supply used in the differential protection wiring test of the embodiment is a conventional analog load through-flow pressurization test power supply, only needs one set of power supply, and does not need additional equipment for supporting; the primary current amplitudes of the high, medium and low voltage sides are improved by multiple times by effectively utilizing the power supply capacity, so that the aim of improving the amplitude of a secondary current signal is fulfilled; high-pressure boosting is avoided, and safety is high.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A differential protection wiring detection method of a high impedance transformer is characterized by comprising the following steps:
applying a preset voltage on the medium-voltage side of the high-impedance transformer, and measuring to obtain a medium-voltage side secondary current measured value, a high-voltage side secondary current measured value and a low-voltage side secondary current measured value under the experimental condition that the high-voltage side and the low-voltage side are short-circuited;
obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer;
comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
2. The differential protection wiring detection method of a high impedance transformer according to claim 1, wherein the medium voltage side secondary current measurement value, the high voltage side secondary current measurement value and the low voltage side secondary current measurement value are directly obtained by using an ammeter.
3. The differential protection wiring detection method of a high impedance transformer according to claim 1, wherein the calculation process of the calculated value of the secondary current on the medium voltage side, the calculated value of the secondary current on the high voltage side and the calculated value of the secondary current on the low voltage side under the same experimental conditions is as follows:
obtaining a primary current of the medium-voltage side according to the voltage pressurized by the medium-voltage side of the high-impedance transformer and the parallel equivalent impedance after the medium-voltage side and the low-voltage side are short-circuited;
calculating the currents distributed on the high-voltage side and the low-voltage side according to the distribution relation of the primary current of the medium-voltage side to the high-voltage side and the low-voltage side, and converting the currents into primary short-circuit currents generated on the high-voltage side and the low-voltage side according to corresponding transformation ratios;
according to the transformation ratio of the medium-voltage side, the high-voltage side and the low-voltage side, the medium-voltage side primary current, the high-voltage side primary current and the low-voltage side primary current are converted into a medium-voltage side secondary current, a high-voltage side secondary current and a low-voltage side secondary current respectively.
4. A differential protection wiring detection device of a high impedance transformer is characterized by comprising:
a voltage applying power source for applying a preset voltage to a medium voltage side of the high impedance transformer;
the ammeter is used for measuring a secondary current measured value of the medium-voltage side, a secondary current measured value of the high-voltage side and a secondary current measured value of the low-voltage side under the experimental condition that a preset voltage is applied to the medium-voltage side of the high-impedance transformer and the high-voltage side and the low-voltage side are short-circuited;
a data processor for: obtaining a secondary current calculation value at a medium-voltage side, a secondary current calculation value at a high-voltage side and a secondary current calculation value at a low-voltage side under the same experimental conditions according to the known parameter information of the high-impedance transformer;
comparing whether the measured value of the secondary current at the medium-voltage side, the measured value of the secondary current at the high-voltage side and the measured value of the secondary current at the low-voltage side are respectively corresponding to the calculated value of the secondary current at the medium-voltage side, the calculated value of the secondary current at the high-voltage side and the calculated value of the secondary current at the low-voltage side, and if so, judging that the differential protection wiring of the high-impedance transformer is correct; otherwise, the differential protection wiring error of the high-impedance transformer is judged.
5. The differential protection wiring detection device of a high impedance transformer according to claim 4, wherein said voltage source is an analog load through-current voltage test power source.
6. The differential protection wiring detection device of a high impedance transformer according to claim 4, wherein in the data processor, the calculation process of the calculated value of the secondary current on the medium voltage side, the calculated value of the secondary current on the high voltage side and the calculated value of the secondary current on the low voltage side under the same experimental conditions is as follows:
obtaining a primary current of the medium-voltage side according to the voltage pressurized by the medium-voltage side of the high-impedance transformer and the parallel equivalent impedance after the medium-voltage side and the low-voltage side are short-circuited;
calculating the currents distributed on the high-voltage side and the low-voltage side according to the distribution relation of the primary current of the medium-voltage side to the high-voltage side and the low-voltage side, and converting the currents into primary short-circuit currents generated on the high-voltage side and the low-voltage side according to corresponding transformation ratios;
according to the transformation ratio of the medium-voltage side, the high-voltage side and the low-voltage side, the medium-voltage side primary current, the high-voltage side primary current and the low-voltage side primary current are converted into a medium-voltage side secondary current, a high-voltage side secondary current and a low-voltage side secondary current respectively.
7. The differential protection wiring detection device of a high impedance transformer according to claim 6, wherein the parallel equivalent impedance after the short circuit of the medium voltage side and the low voltage side is equal to the equivalent impedance of the medium voltage side to the high voltage side.
8. The differential protection wiring detection device of a high impedance transformer as claimed in claim 7, wherein the short circuit impedance of the medium voltage to the high voltage is converted from a square of a ratio of voltage levels of the high voltage to the medium voltage multiplied by the short circuit impedance of the high voltage to the medium voltage.
9. The differential protection connection detection device of a high impedance transformer of claim 4, wherein the data processor is further connected to a display for displaying whether the differential protection connection of the high impedance transformer is correct.
10. The differential protection wiring detection device of high impedance transformer of claim 4, wherein the pressurization power source is used for pressurizing to 380V at the medium voltage side of the high impedance transformer.
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| CN112904106A (en) * | 2021-01-15 | 2021-06-04 | 国网山东省电力公司菏泽供电公司 | Multipoint synchronous pilot differential protection direction test system and method |
| CN114280392A (en) * | 2020-09-28 | 2022-04-05 | 国网安徽省电力有限公司阜阳供电公司 | Main transformer simulation load test system |
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| CN112904106A (en) * | 2021-01-15 | 2021-06-04 | 国网山东省电力公司菏泽供电公司 | Multipoint synchronous pilot differential protection direction test system and method |
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