CN113363952B - Power distribution network protection alternating current circuit fault monitoring method based on adjacent node comparison - Google Patents
Power distribution network protection alternating current circuit fault monitoring method based on adjacent node comparison Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
A power distribution network protection alternating current loop fault monitoring method based on adjacent node comparison is characterized by comprising the following steps: step 1, collecting alternating current operation data of an alternating current loop based on the type of the alternating current loop accessed to a current protection node monitored in the power distribution network; step 2, collecting the alternating current operation data on one or two adjacent protection nodes adjacent to the current protection node; and 3, generating a protection alternating current circuit fault criterion based on the alternating current operation data of the current protection node acquired in the step 1 and the alternating current operation data on the adjacent protection node acquired in the step 2, and adjusting a protection action aiming at the protection alternating current circuit based on the fault criterion. The fault criterion in the invention has simple logic, accurate judgment result and high response speed, and solves the problem that the voltage and current criterion fails under special conditions.
Description
Technical Field
The invention relates to the field of power distribution network protection, in particular to a power distribution network protection alternating current loop fault monitoring method based on adjacent node comparison.
Background
In the prior art, power distribution network protection is widely applied to a power distribution network as a necessary means for reducing fault and power failure time in the power distribution network, reducing equipment fault rate, reducing power failure range, realizing power distribution network automation and other beneficial effects. However, the protective action of the power distribution network and the identification of a bus fault in the power distribution network is usually determined only on the basis of the electrical quantity data in the current interval. This makes the existing power distribution network protection technology still have the following problems.
Firstly, in a protection ac circuit with a voltage transformer, the function of monitoring the disconnection of the voltage transformer usually adopts the zero sequence voltage of the ground as the criterion. When a neutral line in the voltage transformer is disconnected, a third harmonic of voltage can be generated, and the characteristics of the third harmonic are very similar to those of zero sequence voltage of fundamental waves, so that disconnection monitoring logic distortion of the traditional voltage transformer is caused, and the condition that a protection alternating current circuit is locked by mistake occurs.
Secondly, in the protection alternating current loop with the current transformer, the realization function of the power distribution network determines that the protection alternating current loop has the characteristic of point-to-multipoint and wide structure, and under the working condition that the power distribution network access circuit operates in a large quantity, the load current in each loop is small, so that the abnormal current in the protection alternating current loop is difficult to distinguish from the current under the normal working condition, and the fault is difficult to distinguish. With the continuous development and wide application of distributed power supply and power grid technologies, the trend of local load balancing is more obvious, which further increases the difficulty of judging abnormal current faults in the protection alternating current loop.
Therefore, a new method for monitoring the fault of the ac circuit for protecting the power distribution network is needed.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a power distribution network protection alternating current loop fault monitoring method based on adjacent node comparison, and original fault criteria are optimized by collecting and comparing electric quantities such as voltage, current and the like in other nodes adjacent to the current node in a protection alternating current loop.
The invention adopts the following technical scheme. A power distribution network protection alternating current loop fault monitoring method based on adjacent node comparison comprises the following steps: step 1, collecting alternating current operation data of an alternating current loop based on the type of the alternating current loop accessed to a current protection node monitored in a power distribution network; step 2, collecting the alternating current operation data on one or two adjacent protection nodes adjacent to the current protection node; and 3, generating a protection alternating current circuit fault criterion based on the alternating current operation data of the current protection node collected in the step 1 and the alternating current operation data on the adjacent protection nodes collected in the step 2, and adjusting protection action logic aiming at the protection alternating current circuit based on the fault criterion.
Preferably, the ac loop types accessed at the current protection node include: the secondary voltage loop comprises a voltage transformer PT and the secondary current loop comprises a current transformer CT.
Preferably, the collected alternating current operation data is three-phase alternating current voltage output by the voltage transformer PT based on a secondary voltage loop containing the voltage transformer PT
And
based on a secondary current loop containing the current transformer CT, the collected alternating current operation data is the overcurrent state of the three-phase current in the protection node where the current transformer CT is located.
Preferably, if one side of the current protection node has an adjacent protection node, collecting alternating current operation data corresponding to the current protection node in the adjacent protection node; if two sides of the current protection node are provided with adjacent protection nodes, collecting alternating current operation data corresponding to the current protection node in the two adjacent protection nodes; the alternating current operation data corresponding to the current protection node is based on the type of the alternating current operation data in the current protection node, and the same type of alternating current operation data in the adjacent protection nodes is collected.
Preferably, the fault criterion of the protection alternating current loop in the secondary voltage loop comprising the voltage transformer PT comprises a first criterion and a second criterion, and when the first criterion and the second criterion are both satisfied, the fault criterion of the protection alternating current loop is satisfied; the first criterion is that the sum of three-phase alternating-current voltages on the current protection node is greater than a voltage threshold; the second criterion is that the ratio of the sum of three-phase alternating-current voltages on at least one adjacent protection node to the sum of three-phase alternating-current voltages on the current protection node is smaller than the difference coefficient of the adjacent nodes.
Preferably, the voltage threshold value is determined by referring to a zero sequence voltage alarm setting value when a secondary circuit of the power distribution network is abnormal; the difference coefficient of the adjacent nodes is determined based on the ratio of zero sequence voltages of all protection nodes in the power distribution network when the protection nodes are in a grounding state; each protection node comprises a current protection node and an adjacent protection node.
Preferably, the voltage threshold is 8V and the adjacent node difference coefficient is 0.8.
Preferably, the fault criterion of the protection alternating current loop in the secondary current loop including the current transformer CT includes a third criterion and a fourth criterion, and when the third criterion and the fourth criterion are both satisfied, the fault criterion of the protection alternating current loop is satisfied; the third criterion is that the bus differential motion criterion on the current protection node is met; the fourth criterion is that the phase of the bus differential motion of the three-phase current on the current protection node is different from the phase of the overcurrent state of the three-phase current on each adjacent protection node and the phase of the outlet overcurrent state on the adjacent protection node.
Preferably, the phase difference is that the phase where any bus differential motion in the current protection node is located is not covered by the phase where the overcurrent state of the three-phase current on the adjacent protection node is located and the phase where the outgoing line overcurrent state on the adjacent protection node is located.
Preferably, the differential protection action of each phase in the three-phase bus differential protection is started based on that the phase current of the corresponding phase in the protection node is in an overcurrent state.
Preferably, when the fault criterion of the secondary voltage loop is met, an alarm signal of the PT disconnection of the voltage transformer is sent out, and the protection function influenced by the secondary voltage is correspondingly switched off based on the state of the secondary voltage loop; and when the fault criterion of the secondary current loop is established, sending an alarm signal of the disconnection of the current transformer CT, and locking the bus differential protection.
Compared with the prior art, the method for monitoring the fault of the power distribution network protection alternating current circuit by comparing the adjacent nodes has the advantages that the electric quantities such as voltage, current and the like in other nodes adjacent to the current node in the protection alternating current circuit can be collected and compared with the corresponding electric quantities in the current node, so that the original fault criterion is optimized. The fault criterion in the invention has simple logic, accurate judgment result and high response speed, and solves the problem that the voltage and current criterion fails under special conditions.
The beneficial effects of the invention also include:
1. in the secondary voltage loop, in order to prevent the interference of the third harmonic of the voltage on the disconnection monitoring logic of the voltage transformer when the neutral line of the voltage transformer has the disconnection fault, the invention not only monitors the sum of the three-phase voltage in the protection node, but also compares the sum with the same parameter of the adjacent node, thereby eliminating the influence of the third harmonic of the voltage on the disconnection monitoring logic and accurately judging the disconnection fault of the voltage transformer.
2. In the secondary current loop, in order to accurately distinguish common bus faults and current transformer disconnection faults on bus protection nodes, the protection action states of adjacent protection nodes are collected and compared with the protection action state of the current node, so that the misoperation caused by the disconnection of the current transformer is accurately identified, and the bus differential protection is locked in time when the misoperation occurs.
3. The method can effectively utilize the voltage and current information of the adjacent nodes to accurately distinguish the power grid fault and the circuit defect, thereby solving the problem that the original voltage and current fault monitoring criterion is possibly invalid under some special operating conditions. By adding corresponding criteria, the reliability and accuracy of fault identification of the protection voltage and the protection current are better improved.
4. When the criterion takes effect, the bus differential protection is locked in time, so that the fault removal which is only executed on the whole area due to the disconnection fault of the voltage transformer and the current transformer is prevented, unnecessary power failure is prevented, the fault removal range is reduced, and the expansion of the accident is prevented in time.
Drawings
Fig. 1 is a schematic diagram of a bus protection arrangement in a power distribution network protection ac circuit fault monitoring method based on adjacent node comparison according to the present invention;
fig. 2 is a schematic diagram of bus protection when a secondary current loop fails in the power distribution network protection ac loop fault monitoring method based on adjacent node comparison according to the present invention;
fig. 3 is a schematic wiring diagram of a bus protection circuit and a secondary current circuit in the power distribution network protection alternating current circuit fault monitoring method based on adjacent node comparison.
Detailed Description
The present application is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present application is not limited thereby.
Fig. 1 is a schematic diagram of bus protection setting in a power distribution network protection ac circuit fault monitoring method based on adjacent node comparison according to the present invention. As shown in fig. 1, a method for monitoring a fault of a protection ac loop of a power distribution network based on comparison between adjacent nodes includes steps 1 to 3.
Step 1, collecting alternating current operation data of an alternating current loop based on the type of the alternating current loop accessed to a current protection node monitored in a power distribution network.
Each protection node in the invention is respectively positioned on each bus. Three protection nodes P, M and N in the three buses in FIG. 1 are respectively located between G and DG, and the three buses are connected through two bus tie lines. Specifically, for the three buses described above, the voltage at P, M and N for each protection node is recorded as U, respectively P 、U M And U N . Generally, the G terminal has a relatively high voltage and may be a transformer device, and the DG terminal has a relatively low voltage and may be a distributed power source.
In the invention, in order to prevent the node protection misoperation caused by the disconnection of a voltage transformer or a current transformer on a certain protection node, each of the three protection nodes can be sequentially selected as a current node, and whether the current node has the misoperation condition or not can be judged according to the method in the invention.
Preferably, the ac loop types accessed at the current protection node include: the secondary voltage loop comprises a voltage transformer PT and the secondary current loop comprises a current transformer CT.
Generally, a circuit connected to a Potential Transformer (PT) or a circuit connected to a Current Transformer (CT) may be used as the secondary voltage circuit or the secondary Current circuit on the bus. The bus voltage or the bus current is scaled and monitored in proportion through a voltage or current transformer, so that whether protection action is needed or not is judged. Generally, PT is used to collect the voltage on each protection node, i.e. each bus bar, and CT is used to collect the alternating current between each two protection nodes, i.e. the busties. Specifically, the respective measurement of the current at the two ends of one bus tie can be realized by respectively arranging the CT loops at the two ends of one bus tie.
Preferably, the collected alternating current operation data is three-phase alternating current voltage output by the voltage transformer PT based on a secondary voltage loop containing the voltage transformer PT
And
based on a secondary current loop containing the current transformer CT, the collected alternating current operation data is the action state of the three-phase bus differential protection action in the protection node where the current transformer CT is located.
Specifically, in order to improve the reliability and accuracy of the criterion, the fault criterion in the prior art is upgraded according to different properties of secondary circuits where the voltage transformer and the current transformer are located. Specifically, in order to judge whether a secondary voltage loop where the voltage transformer is located is in a fault state, the three-phase alternating voltage of the voltage transformer can be collected; in order to judge whether the secondary current loop where the current transformer is located is in a fault state, correspondingly, three-phase current can be collected and whether the current transformer is over-current can be judged.
In the invention, in order to reduce the operation process of fault judgment in the current transformer, the action state of the three-phase bus differential protection action determined by whether the current transformer is over-current can be directly acquired.
And 2, collecting the alternating current operation data on one or two adjacent protection nodes adjacent to the current protection node.
In particular, whether the current protection node is adjacent to one or two other protection nodes may be determined based on its location in the bus.
Preferably, if one side of the current protection node has an adjacent protection node, collecting alternating current operation data corresponding to the current protection node in the adjacent protection node; if two sides of the current protection node are provided with adjacent protection nodes, collecting alternating current operation data corresponding to the current protection node in the two adjacent protection nodes; the alternating current operation data corresponding to the current protection node is based on the type of the alternating current operation data in the current protection node, and the same type of alternating current operation data in the adjacent protection nodes is collected.
Specifically, the same type of alternating current operation data in the adjacent protection nodes refers to that if the current protection node collects three-phase voltage, the adjacent protection nodes also collect the three-phase voltage. And if the current protection node collects the three-phase current, collecting the three-phase current in the adjacent protection node. If the current protection node collects the action state of the three-phase bus differential protection action, the adjacent protection node also collects the action state of the three-phase bus differential protection action. After the corresponding data are acquired in the mode, the states of the current protection node and the adjacent protection node can be compared, so that whether the fault occurs on the whole bus or only the voltage or current transformer on the current protection node is judged.
And 3, generating a protection alternating current circuit fault criterion based on the alternating current operation data of the current protection node collected in the step 1 and the alternating current operation data on the adjacent protection nodes collected in the step 2, and adjusting protection actions aiming at the protection alternating current circuit based on the fault criterion.
In the invention, the criterion in the prior art is updated. Specifically, the judgment types of the protection ac circuits are different from each other.
Preferably, the fault criterion of the protection alternating current loop in the secondary voltage loop comprising the voltage transformer PT comprises a first criterion and a second criterion, and when the first criterion and the second criterion are both satisfied, the fault criterion of the protection alternating current loop is satisfied; the first criterion is that the sum of three-phase alternating-current voltages on the current protection node is greater than a voltage threshold; the second criterion is that the ratio of the sum of three-phase alternating-current voltages on at least one adjacent protection node to the sum of three-phase alternating-current voltages on the current protection node is smaller than the difference coefficient of the adjacent nodes.
In particular, the above criterion may be expressed in the form of a formula. According to the illustration in fig. 1, let the current protection node be M and the adjacent protection nodes be P and N, respectively. At the moment, the three-phase alternating voltages of the current protection nodes are respectively collected
And
collecting adjacent protectionThree-phase alternating voltage of node
And
the formula of the criterion is thus:
wherein, U 0PTdz Is a voltage threshold, k 1 Is the coefficient of difference.
Preferably, the voltage threshold value is determined by referring to a zero sequence voltage alarm setting value when a secondary circuit of the power distribution network is abnormal; the adjacent node difference coefficient is determined based on the ratio of zero sequence voltages of all protection nodes in the power distribution network in a grounding state; each protection node comprises a current protection node and an adjacent protection node.
Generally, the ratio of the zero sequence voltages of each node in the grounding mode of the power distribution network is between 0 and 1. Preferably, the present invention can set the difference coefficient to 0.8. Also conventionally, the voltage threshold is set to 8V.
Fig. 2 is a schematic diagram of bus protection when a secondary current loop fails in the power distribution network protection ac loop fault monitoring method based on adjacent node comparison according to the present invention. Fig. 3 is a schematic wiring diagram of a bus protection circuit and a secondary current circuit in the power distribution network protection alternating current circuit fault monitoring method based on adjacent node comparison. As shown in fig. 2-3, when the bus protection type is a protection ac circuit including a current transformer, a disconnection fault of the current transformer may cause a bus protection malfunction under an outside fault, and in the prior art, the disconnection of the current transformer may cause the bus protection malfunction, so that a circuit at the entire protection node M is cut off by the protection, and the fault cutting range is very large.
For example, assuming that any outlet line on the bus protection node M in the distribution network fails, the bus current at point M will exhibit ride-through. At this time, if the outgoing load on the protection node M is small, or the load current is offset due to the existence of the distributed power supply, the situation that the local consumption of the electric energy appears on the bus occurs, which may cause that in the common loop abnormality determination method in the prior art, it may not be accurately determined whether the CT disconnection actually occurs on the current line. When the current transformer CT is disconnected, the bus differential protection action of M points can be caused, all switches are tripped, and the integral power loss of the M station is caused.
Specifically, in the secondary current circuit, the bus differential protection is generally calculated for each of A, B, C three phases. According to different manufacturers of each differential protection device, corresponding protection action criterion equations are slightly different. However, the protection is mostly determined according to whether the three-phase current in A, B, C three phases is overcurrent. If one or more phases of the three-phase current meet the action criterion, the corresponding phase or phases are subjected to differential protection action.
In addition, when each outgoing line of the bus on the current protection node has a fault, fault current is also generated, and when the phase current exceeds the starting value of the protection device, the phase current can be judged to be over-current, so that the phase is protected.
The protection action method is a mode generally adopted in the prior art, and because the error protection caused by the disconnection of the current transformer CT cannot be eliminated, the invention provides further protection action judgment under the mode.
Preferably, the fault criterion of the protection alternating current loop in the secondary current loop including the current transformer CT includes a third criterion and a fourth criterion, and when the third criterion and the fourth criterion are both satisfied, the fault criterion of the protection alternating current loop is satisfied; the third criterion is that the bus differential motion criterion on the current protection node is met; the fourth criterion is that the phase of the bus differential motion of the three-phase current on the current protection node is different from the phase of the overcurrent state of the three-phase current on each adjacent protection node and the phase of the outlet overcurrent state on the adjacent protection node.
Specifically, when the bus differential action on the current protection node is recognized, it may be compared whether the overcurrent phases of the current protection node and the adjacent protection node are consistent. Preferably, the differential protection action of each phase in the three-phase bus differential protection is started based on that the phase current of the corresponding phase in the protection node is in an overcurrent state.
Preferably, the phase difference is that the phase where any bus differential motion in the current protection node is located is not covered by the phase where the overcurrent state of the three-phase current on the adjacent protection node is located and the phase where the outgoing line overcurrent state on the adjacent protection node is located.
As shown in fig. 2 to 3, in the embodiment of the present invention, if the two nodes P, N have different overcurrent phases from the overcurrent phase of the node M, it may be considered that a current transformer CT disconnection fault occurs.
In other cases, for example, when the over-current phase at least one side of P, N completely matches the M-node bus differential operation phase, or when more than M-node bus differential operation phases (that is, when the P-side or N-side over-current phase covers all the M-node bus differential operation phases), or when any of the P-side or N-side outgoing line over-current phases completely matches or completely covers the M-node bus differential operation phase, it is determined that the phases match, that is, when the differential protection on the M-node is caused by a fault at another position on the bus, that is, when a bus fault has indeed occurred, the bus differential protection should be performed.
When the phase difference is identified to be inconsistent, the abnormity can be caused by the disconnection of the current transformer CT, the abnormity of the secondary current loop can be identified, the bus differential protection function of the current protection node M is locked, and the M-point bus differential protection does not act.
Preferably, when the fault criterion of the secondary current loop is met, an alarm signal of the disconnection of the potential transformer PT is sent out, and the protection function influenced by the secondary voltage is correspondingly switched off based on the state of the secondary voltage loop. And when the fault criterion of the secondary current loop is established, sending an alarm signal of the disconnection of the current transformer CT, and locking the bus differential protection.
Specifically, when the criterion in the invention judges that a fault which does not affect the normal operation of the bus occurs in the protection alternating current loop, the corresponding alarm signal can be sent out, and the corresponding function is locked, for example, the bus differential protection is locked, so as to prevent the misoperation of the bus differential protection under the condition.
Specifically, in the secondary voltage loop, load voltage blocking, direction elements or protection withdrawal can be correspondingly switched on or off according to corresponding protection functions in the current secondary loop. In the secondary current circuit, the busbar differential protection can then be blocked accordingly.
Compared with the prior art, the method for monitoring the fault of the power distribution network protection alternating current circuit by comparing the adjacent nodes has the advantages that the electric quantities such as voltage, current and the like in other nodes adjacent to the current node in the protection alternating current circuit can be collected and compared with the corresponding electric quantities in the current node, so that the original fault criterion is optimized. The fault criterion in the invention has simple logic, accurate judgment result and high response speed, solves the problem of failure of the voltage and current criterion under special conditions, and ensures safe and reliable operation of protection actions.
The present applicant has described and illustrated embodiments of the present invention in detail with reference to the accompanying drawings, but it should be understood by those skilled in the art that the above embodiments are merely preferred embodiments of the present invention, and the detailed description is only for the purpose of helping the reader to better understand the spirit of the present invention, and not for limiting the scope of the present invention, and on the contrary, any improvement or modification made based on the spirit of the present invention should fall within the scope of the present invention.
Claims (10)
1. A power distribution network protection alternating current loop fault monitoring method based on adjacent node comparison is characterized by comprising the following steps:
step 1, collecting alternating current operation data of an alternating current loop based on the type of the alternating current loop accessed to a current protection node monitored in the power distribution network;
step 2, collecting the alternating current operation data on one or two adjacent protection nodes adjacent to the current protection node;
step 3, generating a protection alternating current circuit fault criterion based on the alternating current operation data of the current protection node collected in the step 1 and the alternating current operation data on the adjacent protection node collected in the step 2, and adjusting protection action logic aiming at the protection alternating current circuit based on the fault criterion;
the protection alternating current circuit fault criterion in the secondary voltage circuit comprising the voltage transformer PT comprises a first criterion and a second criterion, and when the first criterion and the second criterion are both satisfied, the protection alternating current circuit fault criterion is satisfied;
the first criterion is that the sum of three-phase alternating-current voltages on the current protection node is greater than a voltage threshold;
the second criterion is that the ratio of the sum of three-phase alternating-current voltages on at least one adjacent protection node to the sum of three-phase alternating-current voltages on the current protection node is smaller than a difference coefficient of adjacent nodes.
2. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 1, wherein the method comprises the following steps:
the types of the alternating current loops accessed to the current protection node include: the secondary voltage loop comprises a voltage transformer PT and the secondary current loop comprises a current transformer CT.
3. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 2, wherein the method comprises the following steps:
based on the secondary voltage loop containing the voltage transformer PT, the collected alternating current operation data is the three-phase alternating current voltage output by the voltage transformer PT
And
and based on the secondary current loop containing the current transformer CT, the collected alternating current operation data is the overcurrent state of the three-phase current in the protection node where the current transformer CT is located.
4. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 3, wherein the method comprises the following steps:
if one side of the current protection node is provided with one adjacent protection node, collecting alternating current operation data corresponding to the current protection node in the adjacent protection node;
if two sides of the current protection node are provided with adjacent protection nodes, collecting alternating current operation data corresponding to the current protection node in the two adjacent protection nodes;
the alternating current operation data corresponding to the current protection node is based on the type of the alternating current operation data in the current protection node, and the alternating current operation data of the same type in the adjacent protection nodes are collected.
5. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 4, wherein the method comprises the following steps:
the voltage threshold value is determined by referring to a zero sequence voltage alarm setting value when the secondary circuit of the power distribution network is abnormal;
the adjacent node difference coefficient is determined based on the ratio of zero sequence voltages of all protection nodes in the power distribution network in a grounding state;
wherein each protection node comprises the current protection node and the adjacent protection node.
6. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 5, wherein the method comprises the following steps:
the voltage threshold is 8V, and the adjacent node difference coefficient is 0.8.
7. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 4, wherein the method comprises the following steps:
the fault criterion of the protection alternating current loop in the secondary current loop comprising the current transformer CT comprises a third criterion and a fourth criterion, and when the third criterion and the fourth criterion are both satisfied, the fault criterion of the protection alternating current loop is satisfied; wherein,
the third criterion is that the bus differential motion criterion on the current protection node is satisfied;
the fourth criterion is that the phase of the bus differential motion of the three-phase current on the current protection node is different from the phase of the overcurrent state of the three-phase current on each adjacent protection node and the phase of the outgoing line overcurrent state on the adjacent protection node.
8. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 7, wherein the method comprises the following steps:
the phase difference is that the phase of any bus differential motion in the current protection node is not covered by the phase of the overcurrent state of the three-phase current on the adjacent protection node and the phase of the outlet overcurrent state on the adjacent protection node.
9. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 7, wherein the method comprises the following steps:
the differential protection action of each phase in the three-phase bus differential protection is started based on the condition that the phase current of the corresponding phase in the protection node is in an overcurrent state.
10. The method for monitoring faults of the power distribution network protection alternating current loop based on adjacent node comparison as claimed in claim 1, wherein the method comprises the following steps:
when the fault criterion of the secondary voltage loop is established, sending out a warning signal of PT disconnection of the voltage transformer, and correspondingly switching off the protection function influenced by the secondary voltage based on the state of the secondary voltage loop;
and when the fault criterion of the secondary current loop is established, sending an alarm signal of the disconnection of the current transformer CT, and locking the bus differential protection.
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| CN202110655899.0A CN113363952B (en) | 2021-06-11 | 2021-06-11 | Power distribution network protection alternating current circuit fault monitoring method based on adjacent node comparison |
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| CN202110655899.0A CN113363952B (en) | 2021-06-11 | 2021-06-11 | Power distribution network protection alternating current circuit fault monitoring method based on adjacent node comparison |
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| CN103390887A (en) * | 2013-08-07 | 2013-11-13 | 孙鸣 | Method for isolating faults of power distribution system with micro-grid |
| CN104242274A (en) * | 2014-10-10 | 2014-12-24 | 中国南方电网有限责任公司 | State variable differential protection method for power distribution network accessing to distributed power supply |
| CN105866615A (en) * | 2016-06-16 | 2016-08-17 | 山东大学 | 10kV power distribution line disconnection fault judging method based on three-phase voltage current |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103390887A (en) * | 2013-08-07 | 2013-11-13 | 孙鸣 | Method for isolating faults of power distribution system with micro-grid |
| CN104242274A (en) * | 2014-10-10 | 2014-12-24 | 中国南方电网有限责任公司 | State variable differential protection method for power distribution network accessing to distributed power supply |
| CN105866615A (en) * | 2016-06-16 | 2016-08-17 | 山东大学 | 10kV power distribution line disconnection fault judging method based on three-phase voltage current |
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