CN110275082B - Grounding diagnosis method, system and device for main circuit of converter - Google Patents

Grounding diagnosis method, system and device for main circuit of converter Download PDF

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CN110275082B
CN110275082B CN201810219013.6A CN201810219013A CN110275082B CN 110275082 B CN110275082 B CN 110275082B CN 201810219013 A CN201810219013 A CN 201810219013A CN 110275082 B CN110275082 B CN 110275082B
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voltage
main circuit
ground fault
fault point
phase
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CN110275082A (en
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许峻峰
张志学
胡景瑜
彭赟
付刚
罗文广
苏亮亮
王跃
吴奕
陈欣
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CRRC Zhuzhou Institute Co Ltd
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CRRC Zhuzhou Institute Co Ltd
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Abstract

The application discloses a grounding diagnosis method, a system and a device of a main circuit of a converter, which comprise the following steps: acquiring half-middle direct-current voltage, input voltage and output voltage of a main circuit of the converter, and extracting alternating-current components of the half-middle direct-current voltage; judging whether the alternating current component reaches an operation alternating current value or not; if not, determining that the ground fault point of the converter main circuit is located on a busbar of the converter main circuit; if yes, judging whether the semi-intermediate direct-current voltage meets a voltage abnormal condition; if so, judging that the earth fault point is positioned on the load side of the converter main circuit; and if not, judging that the ground fault point is positioned on the rectifying side or the inverting side of the main circuit of the converter. The position of the ground fault point can be accurately judged by judging whether the alternating current component reaches the running alternating current value and whether the half-middle voltage meets the voltage abnormal condition; and the method and the device have the advantages that the overall data is taken as the main part, the influence of the burr data of the sensor can be ignored, the reliability and the accuracy of judgment are improved, and the method and the device are obviously superior to the prior art.

Description

Grounding diagnosis method, system and device for main circuit of converter
Technical Field
The invention relates to the technical field of electric locomotive fault detection, in particular to a grounding diagnosis method, a grounding diagnosis system and a grounding diagnosis device for a main circuit of a current transformer.
Background
The electric locomotive electric transmission system has the characteristics of high voltage and large current, so that the premise of ensuring the reliable operation of the locomotive is to ensure the normal operation of the transmission system. The main circuit of the locomotive may be grounded due to cable aging, vibration and friction, etc. in the operation process, although normally one-point grounding does not have great influence on the normal operation of the system, when two-point or multi-point grounding exists, a great short-circuit current may be generated, so that the parts of the electric transmission system of the locomotive are burnt, and even the locomotive is broken under severe conditions. Therefore, it is still important and necessary to accurately and rapidly determine and process a ground fault.
The converter is an important ring in an electric transmission system, and possible grounding points of the converter are divided into the following four types: the input end of the rectifying side is grounded, the middle direct current positive and negative busbar is grounded, the inversion output side is grounded, and the load side is grounded. Some methods for detecting the grounding point are provided in the prior art, but the judgment process is simple, and the detection result is not accurate enough. For example, patent CN201210101387.0 proposes a grounding detection device for locomotive auxiliary power supply, which judges the grounding of the load through the detection of the grounding current, and the grounding detection method cannot distinguish the grounding of the inverter output side from the grounding of the load side; and a paper written by the research institute of large-chain locomotives, the company Wang and the company Han and the like, "detection and analysis of the ground fault of the auxiliary converter system of the electric locomotive", which is used for carrying out simulation and ground test verification on the ground judgment mode of the conventional auxiliary converter, has the defects of too simple judgment mode and easy occurrence of false alarm when the voltage sensor has burr interference.
Therefore, how to provide a solution to the above technical problems is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
In view of the above, the present invention provides a method, a system and a device for diagnosing the ground fault of a main circuit of a converter, so as to accurately determine the position of a ground fault point. The specific scheme is as follows:
a grounding diagnosis method for a main circuit of a current transformer comprises the following steps:
acquiring half-middle direct-current voltage, input voltage and output voltage of a main circuit of the converter, and extracting alternating-current components of the half-middle direct-current voltage;
judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if so, judging whether the semi-intermediate direct-current voltage meets a voltage abnormal condition;
if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, according to the voltage amplitude ratio of the alternating current component to the input voltage and the output voltage, the grounding fault point is judged to be positioned on the rectifying side or the inverting side of the converter main circuit.
Preferably, the grounding diagnosis method further includes:
when the ground fault point is positioned on the load side or the inversion side of the converter main circuit, calculating the voltage phase difference between the alternating current component and the output voltage, and determining a target phase according to the voltage phase difference; wherein the target phase is a circuit phase of the three phases in which the ground fault point is located.
Preferably, the converter main circuit comprises a first resistor and a second resistor, a first end of the first resistor is connected with the positive busbar, a first end of the second resistor is connected with the negative busbar, a second end of the first resistor is connected with a second end of the second resistor and then grounded, and the half-middle direct-current voltage is the measurement voltage of the first resistor.
Preferably, after determining that the ground fault point of the converter main circuit is located on the busbar of the converter main circuit, the method further includes:
when the half-middle direct-current voltage is smaller than a first threshold value, judging that the ground fault point is located on the positive busbar;
and when the half-middle direct-current voltage is larger than a second threshold value, judging that the ground fault point is positioned on the negative busbar.
Preferably, the determining that the ground fault point is located on the rectifying side or the inverting side of the converter main circuit according to the voltage amplitude ratios of the alternating current component to the input voltage and the output voltage respectively includes:
calculating a first voltage amplitude proportion of the alternating current component and the input voltage, and a second voltage amplitude proportion of the alternating current component and the output voltage, respectively;
when the first voltage amplitude ratio is in a first amplitude interval, determining that the ground fault point is positioned at the rectifying side of the converter main circuit;
when the second voltage amplitude ratio is in a second amplitude interval, judging that the ground fault point is positioned on the inversion side of the converter main circuit;
the first amplitude interval and the second amplitude interval are obtained according to the resistance values of the first resistor and the second resistor.
Preferably, when the first voltage amplitude ratio is in a first amplitude interval, after determining that the ground fault point is located on a rectification side of the converter main circuit, the method further includes:
calculating a voltage phase difference of the input voltage and the alternating current component;
when the voltage phase difference is in a first phase angle difference interval, determining that the ground fault point is located at the positive end of the rectification side;
when the voltage phase difference is in a second phase angle difference interval, determining that the ground fault point is located at the negative end of the rectification side;
the first phase angle difference interval is a phase angle error allowable interval taking 180 degrees as a midpoint, and the second phase angle difference interval is a phase angle error allowable interval taking 0 degrees as a midpoint.
Preferably, the process of calculating a voltage phase difference between the alternating current component and the output voltage when the ground fault point is located on a load side of the converter main circuit, and determining a target phase according to the voltage phase difference specifically includes:
respectively calculating voltage phase differences between the three-phase voltage of the output voltage and the alternating current component;
and determining the circuit phase corresponding to the voltage phase difference in the first phase angle difference interval as a target phase.
Preferably, the process of calculating a voltage phase difference between the alternating current component and the output voltage when the ground fault point is located on an inverting side of the converter main circuit, and determining a target phase according to the voltage phase difference specifically includes:
respectively calculating voltage phase differences between the three-phase voltage of the output voltage and the alternating current component;
determining a circuit phase corresponding to the voltage phase difference positioned in the third phase angle difference interval as a target phase;
wherein the third phase angle difference interval is a phase angle offset interval taking 180 degrees as a midpoint.
Preferably, the voltage abnormality condition is:
and the proportion of the abnormal range of the half-middle direct current voltage in a single period is greater than a third threshold value.
Preferably, the voltage abnormality condition is:
an abnormality determination value of the half-intermediate direct-current voltage exceeds a fourth threshold value; the abnormal judgment value is a numerical value corresponding to the preset judgment probability of the half-middle direct-current voltage in a single period.
Correspondingly, the invention also discloses a grounding diagnosis system of the main circuit of the converter, which comprises the following components:
the data acquisition module is used for acquiring half-middle direct-current voltage, input voltage and output voltage of the converter main circuit and extracting alternating-current components of the half-middle direct-current voltage;
the first judgment module is used for judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if yes, triggering a second judgment module;
the second judging module is used for judging whether the semi-intermediate direct-current voltage meets the voltage abnormal condition; if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, according to the voltage amplitude ratio of the alternating current component to the input voltage and the output voltage, the grounding fault point is judged to be positioned on the rectifying side or the inverting side of the converter main circuit.
Correspondingly, the invention also discloses a grounding diagnosis device of the main circuit of the converter, which comprises the following components:
a memory for storing a computer program;
a processor for implementing the steps of the grounding diagnostic method of the converter main circuit as described in any one of the above when executing said computer program.
The invention discloses a grounding diagnosis method of a main circuit of a current transformer, which comprises the following steps: acquiring half-middle direct-current voltage, input voltage and output voltage of a main circuit of the converter, and extracting alternating-current components of the half-middle direct-current voltage; judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if so, judging whether the semi-intermediate direct-current voltage meets a voltage abnormal condition; if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, according to the voltage amplitude ratio of the alternating current component to the input voltage and the output voltage, the grounding fault point is judged to be positioned on the rectifying side or the inverting side of the converter main circuit. According to the invention, the alternating current component in the semi-intermediate direct current voltage is extracted, and because the positions of the ground fault points are different, the characteristics of the semi-intermediate direct current voltage are different, the characteristics can be distinguished by judging whether the alternating current component reaches the running alternating current value and whether the semi-intermediate voltage meets the voltage abnormal condition, so that the position of the ground fault point is accurately judged; and the length of data acquired in the diagnosis process is generally single cycle or multi-cycle, the diagnosis basis is mainly the whole data, the influence of the burr data of the sensor can be ignored, the reliability and the accuracy of judgment are improved, and the method is obviously superior to the prior art.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart illustrating steps of a method for diagnosing grounding of a main circuit of a converter according to an embodiment of the present invention;
fig. 2 is a structural topology diagram of a main circuit of a converter in the embodiment of the present invention;
FIG. 3 is a structural topology diagram of a main circuit of a converter with a voltage sensor according to an embodiment of the present invention;
FIG. 4a is a diagram of a ground waveform of a ground fault point according to an embodiment of the present invention;
FIG. 4b is a diagram of a ground waveform of a ground fault point according to an embodiment of the present invention;
FIG. 5 is a diagram of a ground waveform of a ground fault point according to an embodiment of the present invention;
FIG. 6 is a diagram of a ground waveform of a ground fault point according to an embodiment of the present invention;
fig. 7 is a structural distribution diagram of a grounding diagnostic system of a main circuit of a converter according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a grounding diagnosis method of a main circuit of a current transformer, which is shown in a figure 1 and comprises the following steps:
s1: acquiring half-middle direct-current voltage, input voltage and output voltage of a main circuit of the converter, and extracting alternating-current components of the half-middle direct-current voltage;
it is understood that the input voltage of the main circuit of the converter is generally the voltage measured on the rectifying side; the output voltage of the main circuit of the converter is the three-phase voltage output by the main circuit of the whole converter, and is generally measured at the position where the output end of the main circuit of the converter is connected with a load.
The half-middle direct-current voltage is a voltage obtained by measuring a part of a series resistor of the rectifier and the inverter by using two busbars as end points to be connected in series with two or more resistors and a grounding point on the series resistor.
Referring to a structural topological diagram of a main circuit of a converter shown in fig. 2, where possible ground fault points are marked, the ground fault points 1 and 2 are located on a rectification side of the main circuit of the converter, the ground fault points 3 and 4 are located on bus bars of the main circuit of the converter, the ground fault points 5, 6 and 7 are located on an inversion side three-phase line of the main circuit of the converter, and the ground fault points 8, 9 and 10 are located on a load side three-phase line of the main circuit of the converter.
It is understood that the functional circuit block of fig. 2 may be replaced by other circuit blocks with the same function, such as a capacitive-inductive filter block using different wiring schemes.
S2: judging whether the alternating current component reaches an operation alternating current value or not;
wherein, according to the judgment result of the step, step S3 or step S4 is executed.
It can be understood that when the ground fault point is located on the busbar, the ac component of the half-intermediate dc voltage is almost zero, and the operating ac value for determination is preset in consideration of the measurement error, that is, if the ac component does not reach the operating ac value, the fault ground point is considered to be located on the busbar.
S3: if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit;
s4: if so, judging whether the semi-intermediate direct-current voltage meets a voltage abnormal condition;
wherein, according to the judgment result of the step, step S5 or step S6 is executed.
It will be appreciated that the different feature of a fault earth point on the load side, i.e. when the load side is earthed, is that the half-neutral dc voltage itself is abnormal when the load side is earthed, resulting in a measured voltage value outside the normal half-neutral dc voltage range, whereas the half-neutral dc voltage is always within the normal voltage range when the other position is earthed.
Therefore, the voltage abnormality condition is set to determine whether the voltage value exceeds the normal voltage range, and there are generally the following three methods:
firstly, calculating the abnormal range proportion of the half-middle direct-current voltage exceeding the normal range in a single period, wherein the abnormal voltage condition is as follows: the proportion of the abnormal range of the half-middle direct-current voltage in a single period is larger than a certain set threshold value, and the threshold value is generally set to be 10%.
Judging whether the maximum value of the semi-intermediate direct-current voltage exceeds the maximum value of the normal range, and if so, considering that the voltage abnormal condition is met;
thirdly, judging whether the abnormal judgment value of the half-middle direct-current voltage exceeds a certain set threshold value; the abnormal judgment value is a value corresponding to a preset judgment probability of the half-middle direct-current voltage in a single period, and generally the preset judgment probability is 95%.
Of course, there may be other setting rules for setting the voltage abnormality condition, and the setting rules are not limited herein.
S5: if so, judging that the ground fault point is positioned on the load side of the converter main circuit;
s6: if not, according to the voltage amplitude ratio of the alternating current component to the input voltage and the output voltage, the grounding fault point is judged to be positioned on the rectifying side or the inverting side of the converter main circuit.
It can be understood that, when the ground fault point is located on the rectifying side and the inverting side, the ground fault point is judged and analyzed in more detail according to different voltage amplitude ratios, and details are not repeated herein.
Further, because the rectifying side and the inverting side are provided with three-phase circuits, when the specific analysis is carried out on which phase the ground fault point is located, the analysis can be carried out according to the following steps:
calculating a voltage phase difference between the alternating current component and the output voltage, and determining a target phase according to the voltage phase difference; wherein the target phase is a circuit phase of the three phases in which the ground fault point is located.
The invention discloses a grounding diagnosis method of a main circuit of a current transformer, which comprises the following steps: acquiring half-middle direct-current voltage, input voltage and output voltage of a main circuit of the converter, and extracting alternating-current components of the half-middle direct-current voltage; judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if so, judging whether the semi-intermediate direct-current voltage meets a voltage abnormal condition; if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, according to the voltage amplitude ratio of the alternating current component to the input voltage and the output voltage, the grounding fault point is judged to be positioned on the rectifying side or the inverting side of the converter main circuit. According to the invention, the alternating current component in the semi-intermediate direct current voltage is extracted, and because the positions of the ground fault points are different, the characteristics of the semi-intermediate direct current voltage are different, the characteristics can be distinguished by judging whether the alternating current component reaches the running alternating current value and whether the semi-intermediate voltage meets the voltage abnormal condition, so that the position of the ground fault point is accurately judged; and the length of data acquired in the diagnosis process is generally single cycle or multi-cycle, the diagnosis basis is mainly the whole data, the influence of the burr data of the sensor can be ignored, the reliability and the accuracy of judgment are improved, and the method is obviously superior to the prior art.
The embodiment of the invention discloses a specific grounding diagnosis method for a main circuit of a converter, and compared with the previous embodiment, the embodiment further describes and optimizes the technical scheme. Specifically, the method comprises the following steps:
the converter main circuit comprises a first resistor and a second resistor, wherein the first end of the first resistor is connected with a positive busbar, the first end of the second resistor is connected with a negative busbar, the second end of the first resistor is connected with the second end of the second resistor and then grounded, and the half-middle direct-current voltage is the measurement voltage of the first resistor.
As shown in fig. 3Based on fig. 2, a plurality of voltage sensors are connected to the main circuit of the converter in fig. 2 for respectively collecting input voltages USHalf-intermediate direct current voltage Ud-halfIntermediate DC voltage UdAnd a line voltage U of the output voltageabAnd Ubc
It will be appreciated that the line voltage U depends on the output voltageabAnd UbcObtaining Uca=-(Uab+Ubc) Phase voltage of the further output voltage:
the measurement source of the semi-intermediate direct-current voltage is specified, so that the grounding fault point can be more accurately judged according to the positive and negative values of the semi-intermediate direct-current voltage.
Fig. 4a, 4b, 5, and 6 all show the characteristics of the half-intermediate dc voltage when the positions of the ground fault points are different, where fig. 4a and 4b are voltage waveforms of the ground fault point at the positive terminal 1 point and the negative terminal 2 point of the rectifying side, fig. 5 is a voltage waveform of the ground fault point at the output terminal 5 point of the inverting side, and fig. 6 is a voltage waveform of the ground fault point at the output terminal 8 point of the load side, respectively. The following specific determination is made based on the voltage waveform characteristics in the figure.
Specifically, the step S3, where the ac component does not reach the operating ac value, and the ground fault point of the converter main circuit is determined to be located after the busbar of the converter main circuit, further includes:
and when the half-middle direct-current voltage is smaller than a first threshold value, determining that the ground fault point is located on the positive busbar, namely a fault ground point 3.
And when the half-middle direct-current voltage is larger than a second threshold value, judging that the grounding fault point is positioned on the negative busbar, namely a fault grounding point 4.
Wherein the first threshold and the second threshold are typically 10% UdAnd 90% Ud
Further, the step S6 of determining that the ground fault point is located on the rectifying side or the inverting side of the converter main circuit according to the voltage amplitude ratios of the alternating current component to the input voltage and the output voltage respectively includes:
calculating a first voltage amplitude proportion of the alternating current component and the input voltage, and a second voltage amplitude proportion of the alternating current component and the output voltage, respectively;
when the first voltage amplitude ratio is in a first amplitude interval, determining that the ground fault point is positioned at the rectifying side of the converter main circuit;
when the second voltage amplitude ratio is in a second amplitude interval, judging that the ground fault point is positioned on the inversion side of the converter main circuit;
the first amplitude interval and the second amplitude interval are obtained according to the resistance values of the first resistor and the second resistor.
Generally, the resistance values of the first resistor and the second resistor are set to be the same, and theoretically, if the ground fault point is located on the rectifying side, the first voltage amplitude ratio is 1: 2, if the ground fault point is located on the inversion side, the second voltage amplitude ratio is 1: and 1, considering various errors, setting a first amplitude interval corresponding to the first voltage amplitude proportion as an error interval taking 0.5 as a midpoint, and setting a second amplitude interval corresponding to the second voltage amplitude proportion as an error interval taking 1 as a midpoint.
Further, when the first voltage amplitude ratio is in a first amplitude interval, after determining that the ground fault point is located on a rectification side of the converter main circuit, the method further includes:
calculating a voltage phase difference of the input voltage and the alternating current component;
when the voltage phase difference is in a first phase angle difference interval, determining that the ground fault point is located at the positive end of the rectification side;
when the voltage phase difference is in a second phase angle difference interval, determining that the ground fault point is located at the negative end of the rectification side;
the first phase angle difference interval is a phase angle error allowable interval taking 180 degrees as a midpoint, and the second phase angle difference interval is a phase angle error allowable interval taking 0 degrees as a midpoint.
Typically, the first phase angle difference is in the range 180 ° ± 10 °, and the second phase angle difference is in the range 0 ° ± 10 °.
It is understood that the above judgment is designed according to the characteristics of the input voltage and the alternating current component when the positive terminal and the negative terminal of the actual rectification side have ground faults.
Further, the process of calculating a voltage phase difference between the alternating current component and the output voltage when the ground fault point is located on a load side of the converter main circuit, and determining a target phase according to the voltage phase difference specifically includes:
respectively calculating voltage phase differences between the three-phase voltage of the output voltage and the alternating current component;
and determining the circuit phase corresponding to the voltage phase difference in the first phase angle difference interval as a target phase.
It is understood that the three-phase voltages of the output voltage are respectively a-phase, b-phase and c-phase, the voltage phase difference of each phase voltage and the alternating current component is respectively calculated, and if which corresponding voltage phase difference is located in the first phase angle difference interval, the phase is determined to be the target phase.
Further, the process of calculating a voltage phase difference between the alternating current component and the output voltage when the ground fault point is located on an inverting side of the converter main circuit, and determining a target phase according to the voltage phase difference specifically includes:
respectively calculating voltage phase differences between the three-phase voltage of the output voltage and the alternating current component;
determining a circuit phase corresponding to the voltage phase difference positioned in the third phase angle difference interval as a target phase;
wherein the third phase angle difference interval is a phase angle offset interval taking 180 degrees as a midpoint.
Similar to the judgment of the target phase on the load side, when the ground fault on the inverter side occurs, a certain amount of angular deviation exists due to the filter inductance, so that the length of the angular difference interval of the third phase is greater than that of the angular difference interval of the first phase, and generally 180 degrees +/-50 degrees can be adopted.
A specific measurement position of the half-intermediate dc voltage is determined in this embodiment, except for this embodiment, the half-intermediate dc voltage may be obtained through other measurement positions, for example, a voltage waveform of a second resistor in this embodiment is obtained, or other resistors are connected in series and voltage measurement is performed, and the idea is similar to this embodiment, and the scheme may be further refined with reference to details of this embodiment.
Correspondingly, the embodiment of the present invention further discloses a grounding diagnostic system for a main circuit of a converter, as shown in fig. 7, including:
the data acquisition module 01 is used for acquiring a half-middle direct-current voltage, an input voltage and an output voltage of the converter main circuit and extracting an alternating-current component of the half-middle direct-current voltage;
the first judgment module 02 is used for judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if yes, triggering a second judgment module 03;
the second judging module 03 is configured to judge whether the half-intermediate dc voltage meets a voltage abnormality condition; if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, according to the voltage amplitude ratio of the alternating current component to the input voltage and the output voltage, the grounding fault point is judged to be positioned on the rectifying side or the inverting side of the converter main circuit.
The present embodiment has the same advantageous effects as the grounding diagnosis method of the converter main circuit in the above-described embodiments.
Correspondingly, the embodiment of the invention also discloses a grounding diagnosis device of the main circuit of the converter, which comprises the following components:
a memory for storing a computer program;
a processor for implementing the steps of the grounding diagnostic method of the main circuit of the current transformer according to any one of the above embodiments when executing the computer program.
For the details of the grounding diagnosis apparatus in this embodiment, reference may be made to the description of the grounding diagnosis method of the converter main circuit in the above embodiment, and details are not described herein again.
The present embodiment has the same advantageous effects as the grounding diagnosis method of the converter main circuit in the above-described embodiments.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The method, the system and the device for diagnosing the grounding of the main circuit of the converter provided by the invention are described in detail, the principle and the implementation mode of the invention are explained by applying specific examples, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (10)

1. A grounding diagnosis method for a main circuit of a current transformer is characterized by comprising the following steps:
acquiring half-middle direct-current voltage, input voltage and output voltage of a main circuit of the converter, and extracting alternating-current components of the half-middle direct-current voltage;
judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if so, judging whether the semi-intermediate direct-current voltage meets a voltage abnormal condition;
if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, judging that the ground fault point is positioned on the rectifying side or the inverting side of the converter main circuit according to the voltage amplitude ratios of the alternating current component to the input voltage and the output voltage respectively;
the converter main circuit comprises a first resistor and a second resistor, wherein the first end of the first resistor is connected with a positive bus bar, the first end of the second resistor is connected with a negative bus bar, the second end of the first resistor is connected with the second end of the second resistor and then grounded, and the half-middle direct-current voltage is the measurement voltage of the first resistor;
the process of determining that the ground fault point is located on the rectifying side or the inverting side of the converter main circuit according to the voltage amplitude ratios of the alternating current component to the input voltage and the output voltage respectively specifically includes:
calculating a first voltage amplitude proportion of the alternating current component and the input voltage, and a second voltage amplitude proportion of the alternating current component and the output voltage, respectively;
when the first voltage amplitude ratio is in a first amplitude interval, determining that the ground fault point is positioned at the rectifying side of the converter main circuit;
when the second voltage amplitude ratio is in a second amplitude interval, judging that the ground fault point is positioned on the inversion side of the converter main circuit;
the first amplitude interval and the second amplitude interval are obtained according to the resistance values of the first resistor and the second resistor.
2. The grounding diagnostic method according to claim 1, further comprising:
when the ground fault point is positioned on the load side or the inversion side of the converter main circuit, calculating the voltage phase difference between the alternating current component and the output voltage, and determining a target phase according to the voltage phase difference; wherein the target phase is a circuit phase of the three phases in which the ground fault point is located.
3. The ground fault diagnosis method according to claim 2, wherein after determining that the ground fault point of the converter main circuit is located on a busbar of the converter main circuit, the method further comprises:
when the half-middle direct-current voltage is smaller than a first threshold value, judging that the ground fault point is located on the positive busbar;
and when the half-middle direct-current voltage is larger than a second threshold value, judging that the ground fault point is positioned on the negative busbar.
4. The ground fault diagnosis method according to claim 3, wherein when the first voltage amplitude ratio is in a first amplitude range, the determining that the ground fault point is located on the rectification side of the converter main circuit further comprises:
calculating a voltage phase difference of the input voltage and the alternating current component;
when the voltage phase difference is in a first phase angle difference interval, determining that the ground fault point is located at the positive end of the rectification side;
when the voltage phase difference is in a second phase angle difference interval, determining that the ground fault point is located at the negative end of the rectification side;
the first phase angle difference interval is a phase angle error allowable interval taking 180 degrees as a midpoint, and the second phase angle difference interval is a phase angle error allowable interval taking 0 degrees as a midpoint.
5. The grounding diagnosis method according to claim 4, wherein the step of calculating a voltage phase difference between the ac component and the output voltage when the ground fault point is located on the load side of the converter main circuit, and determining a target phase according to the voltage phase difference specifically comprises:
respectively calculating voltage phase differences between the three-phase voltage of the output voltage and the alternating current component;
and determining the circuit phase corresponding to the voltage phase difference in the first phase angle difference interval as a target phase.
6. The ground fault diagnosis method according to claim 5, wherein the process of calculating a voltage phase difference between the ac component and the output voltage when the ground fault point is located on an inverting side of the converter main circuit, and determining a target phase according to the voltage phase difference specifically includes:
respectively calculating voltage phase differences between the three-phase voltage of the output voltage and the alternating current component;
determining a circuit phase corresponding to the voltage phase difference positioned in the third phase angle difference interval as a target phase;
wherein the third phase angle difference interval is a phase angle offset interval taking 180 degrees as a midpoint.
7. The ground fault diagnosis method according to any one of claims 1 to 6, wherein the voltage abnormality condition is:
and the proportion of the abnormal range of the half-middle direct current voltage in a single period is greater than a third threshold value.
8. The ground fault diagnosis method according to any one of claims 1 to 6, wherein the voltage abnormality condition is:
an abnormality determination value of the half-intermediate direct-current voltage exceeds a fourth threshold value; the abnormal judgment value is a numerical value corresponding to the preset judgment probability of the half-middle direct-current voltage in a single period.
9. A system for diagnosing grounding of a main circuit of a converter, comprising:
the data acquisition module is used for acquiring half-middle direct-current voltage, input voltage and output voltage of the converter main circuit and extracting alternating-current components of the half-middle direct-current voltage;
the first judgment module is used for judging whether the alternating current component reaches an operation alternating current value or not; if not, judging that the ground fault point of the converter main circuit is positioned on a busbar of the converter main circuit; if yes, triggering a second judgment module;
the second judging module is used for judging whether the semi-intermediate direct-current voltage meets the voltage abnormal condition; if so, judging that the ground fault point is positioned on the load side of the converter main circuit; if not, judging that the ground fault point is positioned on the rectifying side or the inverting side of the converter main circuit according to the voltage amplitude ratios of the alternating current component to the input voltage and the output voltage respectively;
the converter main circuit comprises a first resistor and a second resistor, wherein the first end of the first resistor is connected with a positive bus bar, the first end of the second resistor is connected with a negative bus bar, the second end of the first resistor is connected with the second end of the second resistor and then grounded, and the half-middle direct-current voltage is the measurement voltage of the first resistor;
the second determining module determines, according to the voltage amplitude ratios of the alternating current component to the input voltage and the output voltage, that the ground fault point is located on a rectification side or an inversion side of the converter main circuit, and specifically includes:
calculating a first voltage amplitude proportion of the alternating current component and the input voltage, and a second voltage amplitude proportion of the alternating current component and the output voltage, respectively;
when the first voltage amplitude ratio is in a first amplitude interval, determining that the ground fault point is positioned at the rectifying side of the converter main circuit;
when the second voltage amplitude ratio is in a second amplitude interval, judging that the ground fault point is positioned on the inversion side of the converter main circuit;
the first amplitude interval and the second amplitude interval are obtained according to the resistance values of the first resistor and the second resistor.
10. An apparatus for diagnosing grounding of a main circuit of a converter, comprising:
a memory for storing a computer program;
processor for implementing the steps of the method for diagnosing grounding of a main circuit of a converter according to any one of claims 1 to 8 when executing said computer program.
CN201810219013.6A 2018-03-16 2018-03-16 Grounding diagnosis method, system and device for main circuit of converter Active CN110275082B (en)

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