CN114184892A - Ground fault monitoring method, system, device and storage medium - Google Patents
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Abstract
The application relates to a ground fault monitoring method, a system, a device and a storage medium, which are applied to monitoring a neutral area line of a high-voltage direct-current transmission system. The ground fault monitoring method comprises the following steps: obtaining a first pole neutral current; changing the first pole neutral line current into a preset current to obtain a changed neutral line current; acquiring a second pole neutral current and an additional electrical parameter after the first pole neutral current changes; judging whether the neutral area line has a ground fault or not based on the changed neutral line current, the second pole neutral line current and the additional electric parameter; the additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is the ground electrode current, and the second electrical parameter is the neutral area voltage and the resistance of the ground line. The method solves the problem that the grounding fault of the neutral area line of the high-voltage direct-current transmission system is not effectively monitored in a bipolar balance operation mode, and simultaneously effectively reduces the risk of bipolar locking caused by the grounding fault of the neutral area line.
Description
Technical Field
The present application relates to the field of high-voltage direct-current power transmission systems, and in particular, to a method, a system, a device, and a storage medium for monitoring a ground fault.
Background
With the development of social economy, the demand for electric power is getting larger and larger, and how to realize more economical and reliable power transmission is getting more and more attention. High-voltage direct-current transmission has obvious advantages in long-distance and high-capacity electric energy transmission, and is gradually the first choice for the construction of the global Internet of energy sources and the east-west power transmission. In order to improve the power transmission reliability, reduce the line loss and inhibit the ground current, a topological structure of grounding neutral points at two ends of a bipolar electrode and a bipolar power balance operation mode are often adopted in a high-voltage direct-current transmission project during high-capacity power transmission.
When a ground fault occurs in the neutral area of bipolar balanced operation, the voltage of the neutral area of bipolar balanced operation is zero, and the ground fault cannot represent the fault amount (no ground current enters the neutral area ground point), so that the direct current protection cannot effectively react to the fault in the bipolar balanced operation.
Currently, ground fault monitoring of a ground line in bipolar balanced operation is mainly performed by a ground impedance monitoring system, which monitors ground line impedance mainly by injecting a high-frequency signal into the ground line to find a ground fault of the ground line. However, since high-frequency components cannot be injected into the neutral bus region and the ground bus region in the station, an effective monitoring means for monitoring a ground fault in the region is still lacking. When the neutral area line is not discovered after the earth fault occurs in the bipolar balanced operation process, if a unipolar latching fault occurs (such as the earthing of a unipolar line, the earthing of a polar bus and the like), the bipolar current balance is broken, the voltage of a neutral area is increased, and the existence of the neutral area grounding point can generate a large earth current, so that the neutral area protection action of a non-latching pole is caused, and the serious consequence of sequential latching in a bipolar short time is caused.
Disclosure of Invention
In view of the above, it is necessary to provide a ground fault monitoring method, system, device and storage medium capable of monitoring a neutral region line of a high voltage direct current transmission system for a ground fault.
In a first aspect, an embodiment of the present application provides an earth fault monitoring method, which is applied to monitoring a neutral area line of a high-voltage direct-current power transmission system, and the earth fault monitoring method includes:
obtaining a first pole neutral current;
changing the first pole neutral line current into a preset current to obtain a changed neutral line current;
acquiring a second pole neutral current and an additional electrical parameter after the first pole neutral current changes;
determining whether a ground fault has occurred in the neutral zone line based on the varying neutral line current, the second pole neutral line current, and the additional electrical parameter;
wherein the additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is a ground electrode current, and the second electrical parameter is a neutral area voltage and a ground line resistance.
According to the ground fault monitoring method, under the condition that the existing neutral point grounding topological structure at two ends of a double pole of the high-voltage direct-current transmission is not changed, the current on the direct-current bus of one pole is changed, appropriate double-pole unbalanced current is actively regulated and generated, corresponding electric quantities are obtained by using the mutual inductor in the existing neutral area line, and whether the neutral area line has the ground fault or not is judged according to the electric quantities, so that the problem that the ground fault of the neutral area line in a double-pole balanced operation mode in the high-voltage direct-current transmission project is not effectively monitored is solved, the operation reliability of the high-voltage direct-current transmission is improved, and the risk of double-pole locking caused by the ground fault of the neutral area line is effectively reduced.
In one embodiment of the first aspect, the preset current is a first preset current or a second preset current, and the changing the first pole neutral current by the preset current to obtain a changed neutral current includes:
if the first pole neutral line current is larger than a first current threshold value, reducing the first pole neutral line current by a first preset current to obtain a variable neutral line current;
and if the first pole neutral line current is smaller than a first current threshold value, increasing the first pole neutral line current by a second preset current to obtain a variable neutral line current.
In one embodiment of the first aspect, the first current threshold is a first multiple of a rated current of the hvdc transmission system, wherein the first multiple is greater than a multiple threshold, and a sum of the first multiple of the rated current and the first current threshold is smaller than the rated current.
In one embodiment of the first aspect, the additional electrical parameter is a first electrical parameter, and the determining whether the neutral zone line has a ground fault based on the changed neutral line current, the second polarity neutral line current, and the additional electrical parameter includes:
and if the sum of the changed neutral line current, the second-pole neutral line current and the grounding electrode current is greater than a second multiple of the grounding electrode current, judging that the neutral area has a grounding fault.
In one embodiment of the first aspect, the additional electrical parameter is a second electrical parameter, and the determining whether the neutral zone line has a ground fault based on the changed neutral line current, the second polarity neutral line current, and the additional electrical parameter includes:
and if the neutral area voltage is less than a third multiple of the product of the sum of the neutral line currents and the grounded line resistance, determining that the neutral area has a ground fault, wherein the sum of the neutral line currents is the sum of the changed neutral line current and the second polarity neutral line current.
In one embodiment of the first aspect, if it is determined that a ground fault occurs in the neutral region, the power of the high-voltage direct-current power transmission system is controlled to be reduced to a preset power, and an alarm signal is generated.
In one embodiment of the first aspect, after the obtaining the first neutral current, before changing the first neutral current by a preset current to obtain a changed neutral current, the method further includes:
acquiring the current and the bipolar power of a second-pole neutral line, and judging whether a locking signal is generated or not;
and if the sum of the first pole neutral line current and the second pole neutral line current is smaller than a second current threshold value, the bipolar power is larger than a power threshold value, and a locking signal is judged not to be generated, changing the first neutral line current into a preset current.
In a second aspect, embodiments of the present application provide a ground fault monitoring system, comprising:
a first current transformer for detecting a first pole neutral current;
a second current transformer for detecting a second pole neutral current;
the additional sensor comprises a first sensor or a second sensor, the first sensor is a third current transformer and is used for detecting the current of the grounding pole, and the second sensor is a voltage transformer and is used for detecting the voltage of the neutral area;
a controller connected to the first current transformer, the second current transformer and the additional sensor, the controller comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the method of any of the above embodiments when executing the computer program.
In a third aspect, an embodiment of the present application provides an earth fault monitoring device for monitoring a neutral area line of a high-voltage direct-current transmission system, the earth fault monitoring device including:
the first acquisition module is used for acquiring a first pole neutral current;
the current change module is used for changing the first pole neutral line current into a preset current to obtain a changed neutral line current;
the second acquisition module is used for acquiring the second pole neutral current and the additional electrical parameter after the first pole neutral current changes;
the fault judgment module is used for judging whether the neutral area line has a ground fault or not based on the change neutral line current, the second pole neutral line current and the additional electrical parameter;
wherein the additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is a ground electrode current, and the second electrical parameter is a neutral area voltage and a ground line resistance.
In a fourth aspect, embodiments of the present application provide a computer-readable storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the method of any of the above embodiments.
It is to be understood that, for the beneficial effects that can be achieved by the ground fault monitoring system according to the second aspect, the ground fault monitoring device according to the third aspect, and the computer-readable storage medium according to the fourth aspect, reference may be made to the ground fault monitoring method according to the first aspect and the beneficial effects in any one of the embodiments, which are not repeated herein.
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In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method for ground fault monitoring in one embodiment;
fig. 2 is a schematic diagram of a neutral zone line of a high voltage direct current transmission system;
FIG. 3 is a schematic flow chart of a ground fault monitoring method in another embodiment;
FIG. 4 is a schematic diagram of a ground fault monitoring system in one embodiment;
fig. 5 is a block diagram of a ground fault monitoring device in an embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
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 application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It is to be understood that the terms "first", "second", and the like, as used herein, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to a number of technical features being indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. The terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. Further, in the description of the present application, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In the description of the present application, "a number" means at least one, such as one, two, etc., unless specifically limited otherwise.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, as used in this specification, the term "and/or" includes any and all combinations of the associated listed items.
In one embodiment, as shown in fig. 1, there is provided a ground fault monitoring method for monitoring a neutral area line of a high voltage direct current transmission system, the ground fault monitoring method comprising steps S100 to S400.
And S100, acquiring a first pole neutral current.
As shown in fig. 2, fig. 2 shows a neutral area line of a hvdc transmission system, the neutral area line being connected in series between two groups of converter units, the neutral area line being connected in a bipolar two-terminal neutral grounding mode, wherein, the pole 1 represents positive polarity to the ground, the pole 2 represents negative polarity to the ground, the current transformer CT1 is positioned on the neutral DC bus of the pole 1, the current transformer CT2 is positioned on the neutral DC bus of the pole 2, the current transformer CT3 is positioned on the ground bus, the neutral area refers to the operation of bipolar current balance, the region with voltage to ground of 0, in particular the region line surrounded by CT1, CT2, CT3 in fig. 2, the first pole neutral current may be the current on the neutral dc bus of pole 1, i.e. the current detected by CT1, may also be the current on the neutral dc bus of pole 2, i.e. the current detected by CT 2.
And S200, changing the first pole neutral line current into a preset current to obtain a changed neutral line current.
Under normal conditions, the current magnitude on the medium-voltage direct-current buses corresponding to the poles 1 and 2 is equal, when the currents on the two poles are unbalanced, the voltage to the ground of the neutral area line is not 0, and whether the neutral area line has a ground fault or not can be monitored. The current of the neutral line of the first pole is changed into a preset current, so that unbalanced current is generated between the pole 1 and the pole 2, and whether the neutral area has ground fault or not can be judged according to corresponding electrical parameters.
And S300, acquiring a second pole neutral current and an additional electric parameter after the first pole neutral current is changed.
When an unbalanced current is generated between the poles 1 and 2 after the change of the first pole neutral line, the determination parameters for determining the ground fault, that is, the second pole neutral line current and the additional electrical parameter are acquired to perform the ground fault determination. The second neutral line current is a current on the neutral bus of the other pole different from the first neutral line current, that is, if the first neutral line current is a current on the neutral dc bus of the pole 1, the second neutral line current is a current on the neutral dc bus of the pole 2; if the first pole neutral current is the current on the pole 2 neutral dc bus, then the second neutral current is the current on the pole 1 neutral dc bus. The additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is a ground electrode current, and the ground electrode current is a current on a ground bus in a neutral area line, that is, a current detected by the current transformer CT3 in fig. 2. The second electrical parameter is neutral area voltage and resistance of the grounding line, the neutral area voltage is a voltage value detected by the direct current voltage transformer PT in fig. 2, and the resistance of the grounding line is the sum of the resistance from the current transformer CT3 to the grounding electrode line in fig. 2 and the resistance of the grounding electrode.
And S400, judging whether the neutral area line has a ground fault or not based on the changed neutral line current, the second-pole neutral line current and the additional electric parameter.
Specifically, different judgment modes can be adopted to judge whether the neutral area line has the ground fault according to different acquired additional electrical parameters. After the first pole neutral line current is changed, if the neutral area line has no ground fault, the sum of the changed neutral line current and the second pole neutral line current is the ground pole current, and if the ground fault occurs, current flows out from the ground point to generate a difference current during bipolar unbalanced operation. The relationship between the varying neutral line current, the second polarity neutral line current, and the ground electrode current can be used to determine whether a ground fault has occurred in the neutral region. When the two-pole current is unbalanced, the neutral-zone line generates a voltage, and if the neutral zone is not in a ground fault, the neutral-zone voltage is a product of the unbalanced current and the resistance of the ground line, and the unbalanced current is related to the changed neutral line current and the second-pole neutral line current. Or the judgment can be carried out according to the first electrical parameter and the second electrical parameter at the same time, and the judgment condition at the same time is possibly different from the judgment condition independently.
According to the ground fault monitoring method, under the condition that the existing neutral point grounding topological structure at two ends of a double pole of high-voltage direct-current transmission is not changed, appropriate double-pole unbalanced current is generated through active adjustment by changing the current on the direct-current bus of one pole, corresponding electric quantities are obtained by using a mutual inductor in the existing neutral area line, and whether the neutral area line has ground fault or not is judged according to the electric quantities, so that the problem that the ground fault of the neutral area line in a double-pole balanced operation mode in the high-voltage direct-current transmission project is not effectively monitored is solved, the operation reliability of the high-voltage direct-current transmission is improved, and the risk of double-pole locking caused by the ground fault of the neutral area line is effectively reduced.
In one embodiment, the preset current is a first preset current or a second preset current, and the step S200 specifically includes: if the first pole neutral line current is larger than a first current threshold value, reducing the first pole neutral line current by a first preset current to obtain a variable neutral line current; and if the first pole neutral line current is smaller than a first current threshold value, increasing the first pole neutral line current by a second preset current to obtain a variable neutral line current.
Specifically, as shown in fig. 3, the variation of the first pole neutral current is determined according to the magnitude of the first pole neutral current. If the first pole neutral line current is larger than the first current threshold value, in order to avoid that the change of the first pole neutral line current exceeds the rated current of the high-voltage direct-current transmission system, the first pole neutral line current is reduced by a first preset current, so that an unbalanced current equal to the first preset current is generated between the two poles. If the first pole neutral current is less than the first current threshold, the first pole neutral current may be increased by a second predetermined current, so that an unbalanced current equal to the second predetermined current is generated between the two poles. The first predetermined current and the second predetermined current may be equal or different.
In one embodiment, the first current threshold is a first multiple of a rated current of the hvdc transmission system, wherein the first multiple is greater than a multiple threshold, and a sum of the first multiple of the rated current and the preset current is less than the rated current.
In particular, the first current threshold is determined from a rated current of the hvdc transmission system and a preset current, in particular the first current threshold is a first multiple of the rated current of the hvdc transmission system and the second current threshold is a second multiple of the rated current of the hvdc transmission systemThe multiple is determined according to the preset current, the first multiple is larger than a multiple threshold value, and the sum of the first multiple of the rated current and the preset current is smaller than the rated current, so that the first multiple is larger than the multiple threshold value and is also smaller than 1, and the multiple threshold value is smaller than 1. In some embodiments, the multiple threshold is 0.85 to 0.95. For example: the first multiple is k1Multiple threshold of 0.9 and rated current of InThe predetermined current is IdThen the first current threshold is In×k1，k1Needs to satisfy k1>0.9 and Inxk1+Id＜In。
In one embodiment, the additional electrical parameter is a first electrical parameter, and the step S300 specifically includes: and if the sum of the changed neutral line current, the second-pole neutral line current and the grounding electrode current is greater than a second multiple of the grounding electrode current, judging that the neutral area has a grounding fault.
In this embodiment, the fault condition of the neutral region line is determined by specifically changing the neutral line current, the second polarity neutral line current, and the ground electrode current. The judgment formula is as follows: | IDL1+IDL2+IDL3|＞k2×|IDL3L, wherein IDL1For varying neutral current, IDL2For second pole neutral current, IDL3Is the earth electrode current, k2Is the second multiple. If the sum of the changed neutral line current, the second neutral line current and the earth electrode current is the vector sum of the changed neutral line current, the second neutral line current and the earth electrode current, and the changed neutral line current, the second neutral line current and the earth electrode current meet the judgment formula, the neutral line area is judged to have the earth fault, and the second multiple can be determined according to the relation of the three currents before and after the fault.
In one embodiment, the additional electrical parameter is a second electrical parameter, and the step S300 specifically includes: and if the neutral area voltage is less than a third multiple of the product of the sum of the neutral line currents and the grounded line resistance, determining that the neutral area has a ground fault, wherein the sum of the neutral line currents is the sum of the changed neutral line current and the second polarity neutral line current.
In this embodiment, the neutral line fault is determined by changing the neutral line current, the second polarity neutral line current, the neutral area voltage, and the ground line resistance. The judgment formula is as follows: i UDN < k3×|IDL1+IDL2I x Rd, where UDN is the neutral region voltage, Rd is the ground line resistance, k3Is a third multiple. The sum of the varying neutral current and the second polarity neutral current is a vector sum of the varying neutral current and the second polarity neutral current. If the changed neutral line current, the second polarity neutral line current, the neutral region voltage, and the ground line resistance satisfy the above determination formula, it is determined that the neutral region has the ground fault, and the second multiplier may be determined according to the relationship between the changed neutral line current, the second polarity neutral line current, the neutral region voltage, and the ground line resistance before and after the fault.
In one embodiment, if a time that a sum of the varying neutral line current, the second polarity neutral line current, and the ground electrode current continues to be greater than a second multiple of the ground electrode current exceeds a first preset time, or a time that the neutral region voltage continues to be less than a third multiple of a product of the sum of the neutral line currents and the ground line resistance exceeds a second preset time, it is determined that the neutral region has a ground fault.
When the corresponding electrical parameters are monitored to meet the ground fault judgment conditions, whether the time for continuously meeting the judgment conditions exceeds the corresponding preset time is judged, if yes, the ground fault is judged to occur, and the judgment accuracy is guaranteed.
In one embodiment, as shown in fig. 3, if it is determined that the neutral region has a ground fault, the power of the high-voltage direct-current transmission system is controlled to be reduced to a preset power and an alarm signal is generated.
In this embodiment, after it is determined that the ground fault occurs in the neutral region, the operating power of the high-voltage direct-current transmission system needs to be reduced to the preset power, so that even if the line in the neutral region has the ground fault, the operation of the high-voltage direct-current transmission system under the preset power does not affect the whole grid system, and the high-voltage direct-current transmission system can still operate normally under the condition that the ground fault occurs in the line in the neutral region is not found in time. The preset power is also selected according to the current operation condition of the system, and the basis is that the power lost after the bipolar locking of the high-voltage direct-current power transmission system cannot cause great influence on the safe and stable operation of the power system. And generating an alarm signal while reducing power so as to inform related personnel to maintain the line in the neutral area in time.
In one embodiment, as shown in fig. 3, the determination of the ground fault is a periodic monitoring, after the first pole neutral line current changes, it is determined whether the current condition of the neutral area line meets the above criterion of the occurrence of the ground fault within a fourth preset time, if the current condition of the neutral area line does not meet the criterion of the occurrence of the ground fault within the fourth preset time, the waiting logic is entered, and after waiting for a fifth preset time, the magnitude of the first pole neutral line current is monitored and determined again.
In one embodiment, after step S100, before step S200, the method further includes:
m10, acquiring the current and the bipolar power of a second-pole neutral line, and judging whether a locking signal is generated or not;
m20, if the sum of the first pole neutral line current and the second pole neutral line current is smaller than a second current threshold value, the bipolar power is larger than a power threshold value, and a locking signal is judged not to be generated, changing the first neutral line current into a preset current.
In particular, bipolar power refers to power of the hvdc transmission system, which is controlled and monitored by a dc protection. If the step of changing the first-pole neutral line current is started, the neutral region earth fault judgment logic is started, before the neutral region earth fault judgment logic is started, a neutral region line needs to meet corresponding conditions, namely, whether the current operation mode of the high-voltage direct-current power transmission system is a bipolar power balance operation mode is determined, and the judgment formula is as follows: | IDL1+IDL2|＜IpWherein, IpIs the second current threshold, if the judgment formula is satisfiedIf the sum of the first pole neutral current and the second pole neutral current is smaller than the second current threshold value, the operation mode of the high-voltage direct current transmission system is bipolar balanced operation, wherein the sum of the first pole neutral current and the second pole neutral current is a vector sum of the first pole neutral current and the second pole neutral current. And secondly, determining whether the bipolar power of the current high-voltage direct-current power transmission system is larger than a power threshold value, wherein the power threshold value is selected according to the current operation condition of the high-voltage direct-current power transmission system, and the basis is that the power lost after bipolar locking of the high-voltage direct-current power transmission system cannot cause great influence on the overall safe and stable operation of the high-voltage direct-current power transmission system. And thirdly, determining whether a blocking signal is generated, wherein the blocking signal comprises a related circuit protection action signal, a related measuring point data abnormal signal or a related control protection host abnormal signal, the related circuit protection action signal refers to a protection action signal such as a direct current line protection action, a direct current open circuit protection action and the like, and the related measuring point data abnormal signal refers to measurement abnormality of detection equipment such as a current transformer, a voltage transformer and the like. The related control and protection host exception refers to the exception of the execution main body of the method in the scheme. The generation of these abnormal signals indicates that another fault condition has occurred in the line, in which case it is not desirable to make a determination of a neutral zone line ground fault.
In some embodiments, the ground fault determination process is stopped if a lockout signal occurs during the neutral zone line ground fault determination process.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 1 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least a portion of the other steps or stages.
In one embodiment, as shown in fig. 4, there is provided a ground fault monitoring system for monitoring a neutral area line of a high voltage direct current transmission system, the ground fault monitoring system comprising: a first current transformer 510, a second current transformer 520, an additional sensor 530, and a controller 540. The first current transformer 510 is used to detect a first pole neutral current; the second current transformer 520 is used for detecting a second polar neutral current; the additional sensor 530 includes a first sensor, which is a third current transformer for detecting the ground current, or a second sensor, which is a voltage transformer for detecting the neutral zone voltage; a controller 540 is connected to the first current transformer 510, the second current transformer 520 and the additional sensor 530, the controller 540 comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the above-mentioned method embodiments when executing the computer program.
Specifically, as shown in fig. 2, a neutral area line is connected in series between two sets of inverter units, the connection mode of the neutral area line is a bipolar both-end neutral point grounding mode, a first current transformer 510 is disposed on a neutral dc bus of one pole, a second current transformer 520 is disposed on a neutral dc bus of the other pole, an additional sensor 530 adopted according to different determination modes is different, a third current transformer is disposed on a ground line, and a voltage transformer is connected with the neutral dc bus of the pole 1 or with the neutral dc bus of the pole 2. In some embodiments, the measurement accuracy of the first current transformer, the second current transformer and the third current transformer is not less than 0.01A, and/or the measurement accuracy of the voltage transformer is not less than 0.1V, so that the purpose of accurately measuring the current and the voltage can be achieved.
In one embodiment, as shown in fig. 5, there is provided a ground fault monitoring device for monitoring a neutral area line of a high voltage direct current transmission system, the ground fault monitoring device 600 comprising: a first obtaining module 610, a current changing module 620, a second obtaining module 630 and a fault judging module 640; the first obtaining module 610 is configured to obtain a first pole neutral current; the current change module 620 is configured to change the first pole neutral current to a preset current to obtain a changed neutral current; the second obtaining module 630 is configured to obtain a second polar neutral current and the additional electrical parameter after the first polar neutral current changes; the fault determining module 640 is configured to determine whether a ground fault occurs in the neutral area line based on the changed neutral line current, the second pole neutral line current, and the additional electrical parameter; wherein the additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is a ground electrode current, and the second electrical parameter is a neutral area voltage and a ground line resistance.
In an embodiment, the preset current is a first preset current or a second preset current, and the current variation module is specifically configured to reduce the first pole neutral current by the first preset current to obtain a varied neutral current if the first pole neutral current is greater than a first current threshold; and if the first pole neutral line current is smaller than a first current threshold value, increasing the first pole neutral line current by a second preset current to obtain a variable neutral line current.
In one embodiment, the additional electrical parameter is a first electrical parameter, and the determining module is specifically configured to determine that a ground fault occurs in the neutral region if a sum of the changed neutral line current, the second polarity neutral line current, and the ground electrode current is greater than a second multiple of the ground electrode current.
In one embodiment, the additional electrical parameter is a second electrical parameter, and the determining module is specifically configured to determine that a ground fault occurs in the neutral region if the neutral region voltage is less than a third multiple of a product of a sum of neutral currents and the ground line resistance, where the sum of neutral currents is a sum of the changed neutral current and the second polarity neutral current.
In one embodiment, if the neutral region is determined to have a ground fault, the power of the high-voltage direct-current power transmission system is controlled to be reduced to a preset power and an alarm signal is generated.
In one embodiment, the ground fault monitoring arrangement of the high voltage direct current transmission system further comprises: the monitoring and judging module is used for acquiring the current and the bipolar power of the second-pole neutral line and judging whether a locking signal is generated or not; and if the sum of the first pole neutral line current and the second pole neutral line current is smaller than a second current threshold value, the bipolar power is larger than a power threshold value, and a locking signal is judged not to be generated, changing the first neutral line current into a preset current.
In an embodiment, a computer-readable storage medium is provided, on which a computer program is stored, which computer program, when being executed by a processor, carries out the steps of the above-mentioned method embodiments.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. An earth fault monitoring method for monitoring a neutral zone line of a high voltage direct current transmission system, the earth fault monitoring method comprising:
obtaining a first pole neutral current;
changing the first pole neutral line current into a preset current to obtain a changed neutral line current;
acquiring a second pole neutral current and an additional electrical parameter after the first pole neutral current changes;
determining whether a ground fault has occurred in the neutral zone line based on the varying neutral line current, the second pole neutral line current, and the additional electrical parameter;
wherein the additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is a ground electrode current, and the second electrical parameter is a neutral area voltage and a ground line resistance.
2. The method according to claim 1, wherein the predetermined current is a first predetermined current or a second predetermined current, and the changing the first pole neutral current by the predetermined current comprises:
if the first pole neutral line current is larger than a first current threshold value, reducing the first pole neutral line current by a first preset current to obtain a variable neutral line current;
and if the first pole neutral line current is smaller than a first current threshold value, increasing the first pole neutral line current by a second preset current to obtain a variable neutral line current.
3. The ground fault monitoring method of claim 2, wherein the first current threshold is a first multiple of a rated current of the HVDC transmission system, wherein the first multiple is greater than a multiple threshold, and wherein a sum of the first multiple of the rated current and the first current threshold is less than the rated current.
4. The ground fault monitoring method of claim 1, wherein the additional electrical parameter is a first electrical parameter, and wherein determining whether the neutral zone line has a ground fault based on the varying neutral current, the second polarity neutral current, and the additional electrical parameter comprises:
and if the sum of the changed neutral line current, the second-pole neutral line current and the grounding electrode current is greater than a second multiple of the grounding electrode current, judging that the neutral area has a grounding fault.
5. The ground fault monitoring method of claim 1, wherein the additional electrical parameter is a second electrical parameter, and wherein determining whether the neutral zone line has a ground fault based on the changed neutral current, a second polarity neutral current, and the additional electrical parameter comprises:
and if the neutral area voltage is less than a third multiple of the product of the sum of the neutral line currents and the grounded line resistance, determining that the neutral area has a ground fault, wherein the sum of the neutral line currents is the sum of the changed neutral line current and the second polarity neutral line current.
6. The ground fault monitoring method according to claim 1, characterized by controlling the power of the HVDC transmission system to be reduced to a preset power and generating an alarm signal if it is determined that a ground fault occurs in the neutral region.
7. The ground fault monitoring method of claim 1, wherein after said obtaining the first neutral current, said changing the first neutral current by a predetermined current, and before obtaining a changed neutral current, further comprises:
acquiring the current and the bipolar power of a second-pole neutral line, and judging whether a locking signal is generated or not;
and if the sum of the first pole neutral line current and the second pole neutral line current is smaller than a second current threshold value, the bipolar power is larger than a power threshold value, and a locking signal is judged not to be generated, changing the first neutral line current into a preset current.
8. A ground fault monitoring system for monitoring a neutral area line of a high voltage direct current transmission system, the ground fault monitoring system comprising:
a first current transformer for detecting a first pole neutral current;
a second current transformer for detecting a second pole neutral current;
the additional sensor comprises a first sensor or a second sensor, the first sensor is a third current transformer and is used for detecting the current of the grounding pole, and the second sensor is a voltage transformer and is used for detecting the voltage of the neutral area;
a controller connected to the first current transformer, the second current transformer and the additional sensor, the controller comprising a memory and a processor, the memory storing a computer program, wherein the processor when executing the computer program implements the steps of the method of any one of claims 1 to 7.
9. A ground fault monitoring device for monitoring a neutral area line of a high voltage direct current transmission system, the ground fault monitoring device comprising:
the first acquisition module is used for acquiring a first pole neutral current;
the current change module is used for changing the first pole neutral line current into a preset current to obtain a changed neutral line current;
the second acquisition module is used for acquiring the second pole neutral current and the additional electrical parameter after the first pole neutral current changes;
the fault judgment module is used for judging whether the neutral area line has a ground fault or not based on the change neutral line current, the second pole neutral line current and the additional electrical parameter;
wherein the additional electrical parameter is a first electrical parameter or a second electrical parameter, the first electrical parameter is a ground electrode current, and the second electrical parameter is a neutral area voltage and a ground line resistance.
10. A storage medium having a computer program stored thereon, the computer program, when being executed by a processor, realizing the steps of the method according to any one of claims 1 to 7.
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| CN202111464021.5A CN114184892B (en) | 2021-12-02 | Ground fault monitoring method, system, device and storage medium |
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| CN202111464021.5A CN114184892B (en) | 2021-12-02 | Ground fault monitoring method, system, device and storage medium |
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