CN113363952B - A fault monitoring method for AC circuit protection of distribution network based on comparison of adjacent nodes - Google Patents

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

A fault monitoring method for AC circuit protection of distribution network based on comparison of adjacent nodes

technical field

The invention relates to the field of distribution network protection, and more particularly, to a method for monitoring AC circuit faults of distribution network protection based on the comparison of adjacent nodes.

Background technique

In the prior art, distribution network protection has been widely used in distribution networks as a necessary means to reduce the time of faults and outages in the distribution network, reduce equipment failure rates, reduce the scope of outages, and realize distribution network automation. However, the protection actions of the distribution network and the identification of busbar faults in the distribution network are usually determined only based on the electrical quantity data in the current interval. This makes the existing distribution network protection technology still have the following problems.

First of all, in the protection AC circuit with voltage transformer, the disconnection monitoring function of the voltage transformer usually takes the zero-sequence voltage of grounding as the criterion. When the neutral wire in the voltage transformer is disconnected, the third harmonic of the voltage is generated, and this third harmonic is very similar to the fundamental zero-sequence voltage, causing the traditional voltage transformer disconnection monitoring logic to distort , the protection AC circuit is blocked by mistake.

Secondly, in the protection AC circuit with current transformers, due to the realization function of the distribution network, its structure has the characteristics of being multi-faceted and wide-ranging. The load current is small, which makes it difficult to distinguish the abnormal current in the protection AC circuit from the current under normal working conditions, so the fault is difficult to distinguish. With the continuous development and wide application of distributed power and power grid technology, the trend of local load balancing becomes more and more obvious, which will increase the difficulty of identifying abnormal current faults in the protection AC circuit.

Therefore, there is an urgent need for a new method for monitoring AC circuit faults in distribution network protection.

SUMMARY OF THE INVENTION

In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a fault monitoring method for the protection AC circuit of the power distribution network based on the comparison of adjacent nodes, by comparing other nodes in the protection AC circuit adjacent to the current node. The collection and comparison of electrical quantities such as voltage and current optimizes the original fault criteria.

The present invention adopts the following technical solutions. A method for monitoring AC circuit faults of distribution network protection based on the comparison of adjacent nodes, wherein the method includes the following steps: Step 1: Collect the AC circuit of the AC circuit based on the type of AC circuit connected to the current protection node being monitored in the distribution network. Operation data; step 2, collect the AC operation data on one or two adjacent protection nodes adjacent to the current protection node; step 3, based on the AC operation data of the current protection node collected in step 1, and the data collected in step 2 Based on the AC operation data on the adjacent protection nodes, the fault criterion of the protection AC circuit is generated, and the protection action logic for the protection AC circuit is adjusted based on the fault criterion.

Preferably, the types of AC circuits currently connected to the protection node include: a secondary voltage circuit including a voltage transformer PT, and a secondary current circuit including a current transformer CT.

和

基于包含电流互感器CT的二次电流回路，采集得到的交流运行数据为电流互感器CT所在保护节点中的三相电流的过流状态。Preferably, based on the secondary voltage loop including the voltage transformer PT, the collected AC operation data is the three-phase AC voltage output by the voltage transformer PT

and

Based on the secondary current loop including the current transformer CT, the collected AC 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, collect the AC operation data corresponding to the current protection node in the adjacent protection node; if both sides of the current protection node have adjacent protection nodes, then Collect the AC operation data corresponding to the current protection node in the two adjacent protection nodes; the AC operation data corresponding to the current protection node is based on the type of AC operation data in the current protection node, and collect the same type of AC operation data in the adjacent protection nodes. Operating data.

Preferably, the protection AC circuit fault criterion in the secondary voltage loop including the voltage transformer PT includes a first criterion and a second criterion, and when both the first criterion and the second criterion are satisfied, the protection AC circuit The loop fault criterion is established; wherein, the first criterion is that the sum of the three-phase AC voltages on the current protection node is greater than the voltage threshold; the second criterion is that the sum of the three-phase AC voltages on at least one adjacent protection node and the current protection The ratio of the sum of the three-phase AC voltages on the nodes is smaller than the difference coefficient of adjacent nodes.

Preferably, the voltage threshold is determined with reference to the zero-sequence voltage alarm setting value when the secondary circuit of the distribution network is abnormal; the difference coefficient of adjacent nodes is determined based on the ratio of zero-sequence voltages of each protection node in the distribution network when the grounding state occurs; wherein, Each protection node includes a current protection node and adjacent protection nodes.

Preferably, the voltage threshold is 8V, and the difference coefficient of adjacent nodes is 0.8.

Preferably, the protection AC circuit fault criterion in the secondary current loop including the current transformer CT includes a third criterion and a fourth criterion, and when both the third criterion and the fourth criterion are satisfied, the protection AC circuit The circuit fault criterion is established; the third criterion is that the busbar differential action criterion on the current protection node is satisfied; the fourth criterion is that the current busbar differential action of the three-phase current on the current protection node The phases of the overcurrent states of the three-phase currents on the adjacent protection nodes are different, and the phases of the overcurrent states of the outgoing lines on the adjacent protection nodes are inconsistent.

Preferably, the inconsistency of the phases is that any one of the busbars in the current protection node is in the phase where the differential action of the bus is not in the overcurrent state of the three-phase current on the adjacent protection node, and the outgoing line overcurrent on the adjacent protection node The status is covered separately.

Preferably, the differential protection action of each phase in the three-phase busbar differential protection is activated based on the fact 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 circuit is established, an alarm signal for the disconnection of the voltage transformer PT is issued, and the protection function affected by the secondary voltage is switched on and off accordingly based on the state of the secondary voltage circuit; When the fault criterion of the current loop is established, the alarm signal of the CT disconnection of the current transformer is issued, and the differential protection of the bus is blocked.

The beneficial effect of the present invention is that, compared with the prior art, the method for monitoring the fault of the AC circuit of the protection AC circuit of the protection of the power distribution network by comparing the adjacent nodes in the present invention can detect the voltage of other nodes adjacent to the current node in the protection AC circuit. , current and other electrical quantities are collected, and compared with the corresponding electrical quantities in the current node, thereby optimizing the original fault criterion. The fault criterion in the present invention has simple logic, accurate judgment result and fast response speed, and solves the problem of failure of voltage and current criterion under special circumstances.

The beneficial effects of the present invention also include:

1. In the secondary voltage loop, in order to prevent the third harmonic of the voltage from interfering with the disconnection monitoring logic of the voltage transformer when the neutral line of the voltage transformer is disconnected, the present invention not only monitors the three-phase voltage in the protection node And at the same time, it will be compared with the same parameter of the adjacent node, thus 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 the common busbar fault and the current transformer disconnection fault on the busbar protection node, the present invention collects the protection action state of the adjacent protection node, and compares it with the current node. The fault action caused by the disconnection of the current transformer can be accurately identified, and the bus differential protection will be blocked in time when the fault occurs.

3. The method in the present invention can effectively use the voltage and current information of adjacent nodes to accurately distinguish grid faults and loop defects, thereby solving the problem of the original voltage and current fault monitoring criteria under some special operating conditions. possible failures. By adding corresponding criteria, the reliability and accuracy of fault identification of protection voltage and protection current are better improved.

4. When the criterion is valid, the present invention blocks the bus differential protection in time, thereby preventing the fault removal performed on the entire area due to the disconnection fault of the voltage transformer and the current transformer, and preventing unnecessary power failure. , reducing the scope of fault removal and preventing the expansion of the accident in time.

Description of drawings

1 is a schematic diagram of busbar protection settings in a method for monitoring AC circuit faults in distribution network protection based on adjacent node comparisons of the present invention;

2 is a schematic diagram of busbar protection when a secondary current circuit fails in a method for monitoring AC circuit faults for distribution network protection based on adjacent node comparisons of the present invention;

FIG. 3 is a schematic diagram of the wiring of the busbar protection and the secondary current circuit in a method for monitoring the AC circuit fault of the distribution network protection based on the comparison of adjacent nodes according to the present invention.

Detailed ways

The present application will be further described below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present application.

FIG. 1 is a schematic diagram of busbar protection settings in a method for monitoring AC circuit faults of distribution network protection based on the comparison of adjacent nodes according to the present invention. As shown in FIG. 1 , a method for monitoring AC circuit faults of power distribution network protection based on the comparison of adjacent nodes includes steps 1 to 3 .

Step 1: Collect AC operation data of the AC circuit based on the type of AC circuit connected to the current protection node being monitored in the distribution network.

Each protection node described in the present invention is located on each busbar respectively. The three protection nodes P, M and N of the three bus bars in Fig. 1 are located between G and DG respectively, and the three bus bars are connected through two bus tie lines. Specifically, for the above three bus bars, the voltages of _P , _M and _N of each protection node are recorded as UP , UM and UN , respectively. Generally speaking, the G terminal has a relatively high voltage and can be a transformer device, while the DG terminal has a relatively low voltage and can be a distributed power supply.

In the present invention, in order to prevent the voltage transformer or current transformer on a certain protection node from being disconnected and the node protection misoperation occurs, each of the above three protection nodes can be selected as the current node in turn, and according to the present invention The method judges whether the current node has a misoperation.

Preferably, the types of AC circuits currently connected to the protection node include: a secondary voltage circuit including a voltage transformer PT, and a secondary current circuit including a current transformer CT.

Generally speaking, a circuit connected by a voltage transformer (PT, Potential Transformer) or a circuit connected by a current transformer (CT, Current Transformer) can be used as a secondary voltage loop or a secondary current loop on the bus. The busbar voltage or busbar current is scaled and monitored proportionally through the voltage or current transformer, so as to determine whether the protection action is required. Generally speaking, PT is used to collect the voltage of each protection node, that is, each bus, and CT is used to collect the alternating current between every two protection nodes, that is, between the bus ties. Specifically, the current at both ends of a bus tie can be measured separately by setting CT loops at both ends of a bus tie.

和

基于包含电流互感器CT的二次电流回路，采集得到的交流运行数据为电流互感器CT所在保护节点中的三相母线差动保护动作的动作状态。Preferably, based on the secondary voltage loop including the voltage transformer PT, the collected AC operation data is the three-phase AC voltage output by the voltage transformer PT

and

Based on the secondary current loop including the current transformer CT, the collected AC operation data is the action state of the three-phase busbar 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 present invention upgrades the fault criterion in the prior art according to the different properties of the secondary circuits where the voltage transformer and the current transformer are located. Specifically, in order to determine whether the secondary voltage circuit where the voltage transformer is located is in a fault state, the three-phase AC voltage of the voltage transformer can be collected; and in order to determine whether the secondary current circuit where the current transformer is located is in a fault state, the corresponding , you can collect the three-phase current and judge whether it is overcurrent.

In the present invention, in order to reduce the operation process of judging the fault in the current transformer, the action state of the three-phase busbar differential protection action judged by whether there is overcurrent can also be directly collected.

Step 2: Collect the AC operation data on one or two adjacent protection nodes adjacent to the current protection node.

Specifically, it can be determined whether the current protection node is adjacent to one or two other protection nodes according to the position of the current protection node in the bus.

Preferably, if one side of the current protection node has an adjacent protection node, collect the AC operation data corresponding to the current protection node in the adjacent protection node; if both sides of the current protection node have adjacent protection nodes, then Collect the AC operation data corresponding to the current protection node in the two adjacent protection nodes; the AC operation data corresponding to the current protection node is based on the type of AC operation data in the current protection node, and collect the same type of AC operation data in the adjacent protection nodes. Operating data.

Specifically, the AC operation data of the same type in adjacent protection nodes means that if the current protection node collects three-phase voltages, the three-phase voltages are also collected in adjacent protection nodes. If the three-phase current is collected in the current protection node, the three-phase current is also collected in the adjacent protection node. If the current protection node collects the action state of the three-phase bus differential protection action, the action state of the three-phase bus differential protection action is also collected in the adjacent protection node. Only after the corresponding data is collected in this way, the status of the current protection node and the adjacent protection nodes can be compared to determine whether it is a fault on the entire bus or just the voltage or current mutual inductance on the current protection node. The device has malfunctioned.

Step 3, based on the AC operation data of the current protection node collected in step 1, and the AC operation data on the adjacent protection nodes collected in step 2, generate a protection AC circuit fault criterion, and adjust the protection based on the fault criterion. AC circuit protection action.

In the present invention, the criteria in the prior art are updated. Specifically, for different types of protection AC circuits, the judgment types are also different.

Preferably, the protection AC circuit fault criterion in the secondary voltage loop including the voltage transformer PT includes a first criterion and a second criterion, and when both the first criterion and the second criterion are satisfied, the protection AC circuit The loop fault criterion is established; wherein, the first criterion is that the sum of the three-phase AC voltages on the current protection node is greater than the voltage threshold; the second criterion is that the sum of the three-phase AC voltages on at least one adjacent protection node and the current protection The ratio of the sum of the three-phase AC voltages on the nodes is smaller than the difference coefficient of adjacent nodes.

和

采集相邻保护节点的三相交流电压

和

从而判据的公式形式为：Specifically, the above criteria can be expressed in the form of formulas. As shown in FIG. 1 , the current protection node is M, and the adjacent protection nodes are P and N respectively. At this time, the three-phase AC voltage of the current protection node is collected respectively.

and

Collect three-phase AC voltage of adjacent protection nodes

and

The formula of the criterion is thus:

Among them, U _0PTdz is the voltage threshold, and k ₁ is the difference coefficient.

Preferably, the voltage threshold is determined with reference to the zero-sequence voltage alarm setting value when the secondary circuit of the distribution network is abnormal; the difference coefficient of adjacent nodes is determined based on the ratio of zero-sequence voltages of each protection node in the distribution network when the grounding state occurs; wherein, Each protection node includes a current protection node and adjacent protection nodes.

Generally speaking, the ratio of the zero sequence voltage of each node in the grounding mode of the distribution network is between 0 and 1. Preferably, the present invention can set the difference coefficient to be 0.8. At the same time, by convention, the voltage threshold is set to 8V.

FIG. 2 is a schematic diagram of the busbar protection when the secondary current circuit fails in a method for monitoring the AC circuit fault of distribution network protection based on the comparison of adjacent nodes according to the present invention. FIG. 3 is a schematic diagram of the wiring of the busbar protection and the secondary current circuit in a method for monitoring the AC circuit fault of the distribution network protection based on the comparison of adjacent nodes according to the present invention. As shown in Figure 2-3, when the type of busbar protection is a protection AC circuit including a current transformer, the disconnection fault of the current transformer will cause the faulty operation of the busbar protection under the fault outside the area. The disconnection of the current transformer will cause the busbar protection to malfunction, so that the protection cuts off the entire circuit at the protection node M, and the fault removal range is very large.

For example, if any outgoing line on the busbar protection node M in the distribution network fails, the busbar current at point M will show through. At this time, if the outgoing line load on the protection node M is small, or the load current is offset due to the existence of the distributed power supply, and the local consumption of electric energy appears on the bus, it will cause the circuit commonly used in the prior art. In the abnormality judging method, it is impossible to accurately judge whether the CT disconnection has indeed occurred on the current line. This leads to the disconnection of the current transformer CT, which will also cause the busbar differential protection at point M to trip all switches and cause the overall power loss of the M station.

Specifically, in the secondary current loop, the bus differential protection is usually calculated according to the phases of the three phases A, B, and C. According to the difference of each differential protection equipment manufacturer, the corresponding protection action criterion equation is also slightly different. However, most of them decide whether the protection operates or not according to whether the three-phase current of the A, B, and C phases is overcurrent. If one or more phases of the three-phase current satisfy the action criterion, the corresponding differential protection of this or more phases will act.

In addition, the busbar also generates fault current when each outgoing line on the current protection node fails. When the phase current exceeds the starting value of the protection device, it can also be judged that an overcurrent has occurred in the phase, so that the phase protection action.

The above protection action method is commonly used in the prior art. Since it cannot be ruled out that false protection caused only by the current transformer CT disconnection, the present invention provides further protection action judgment in this way.

Preferably, the protection AC circuit fault criterion in the secondary current loop including the current transformer CT includes a third criterion and a fourth criterion, and when both the third criterion and the fourth criterion are satisfied, the protection AC circuit The circuit fault criterion is established; the third criterion is that the busbar differential action criterion on the current protection node is satisfied; the fourth criterion is that the current busbar differential action of the three-phase current on the current protection node The phases of the overcurrent states of the three-phase currents on the adjacent protection nodes are different, and the phases of the overcurrent states of the outgoing lines on the adjacent protection nodes are inconsistent.

Specifically, when the busbar differential action on the current protection node is identified, it can be compared whether the overcurrent phases of the current protection node and its adjacent protection nodes are consistent. Preferably, the differential protection action of each phase in the three-phase busbar differential protection is activated based on the fact that the phase current of the corresponding phase in the protection node is in an overcurrent state.

Preferably, the inconsistency of the phases is that any one of the busbars in the current protection node is in the phase where the differential action of the bus is not in the overcurrent state of the three-phase current on the adjacent protection node, and the outgoing line overcurrent on the adjacent protection node The status is covered separately.

As shown in Figure 2-3, in the embodiment of the present invention, if the overcurrent phases of the P and N nodes are inconsistent with the overcurrent phases of the M node, it can be considered that a current transformer CT disconnection fault has occurred .

In other cases, for example, the overcurrent phase of at least one side of P and N is completely consistent with the differential action of the M-node busbar, or more than the M-node busbar differential action is different (that is, the P-side or N-side overcurrent phase The phase difference covers all M-node busbar differential actions), or a certain outgoing line overcurrent phase on the P-side or N-side is completely consistent with or completely covered by the busbar differential action of the M-node, then it is judged as a phase difference. The difference is consistent, that is, the differential protection on the M node is caused by the fault at other positions on the bus, that is, a bus fault does occur, and the bus should be differentially protected at this time.

When it is identified that the phases are inconsistent, it can be considered that the abnormality is caused by the disconnection of the current transformer CT, the abnormality of the secondary current loop can be identified, and the bus differential protection function of the current protection node M can be blocked. The busbar differential protection at point M does not act.

Preferably, when the fault criterion of the secondary current loop is established, an alarm signal of disconnection of the voltage transformer PT is issued, and the protection function affected by the secondary voltage is switched on and off accordingly based on the state of the secondary voltage loop. When the fault criterion of the secondary current loop is established, the alarm signal of the CT disconnection of the current transformer is issued, and the differential protection of the busbar is blocked.

Specifically, when the criterion in the present invention determines that there is a fault in the protection AC circuit that will not affect the normal operation of the bus, a corresponding alarm signal can be issued, and the corresponding function can be blocked, such as blocking the bus differential protection, so as to To prevent the misoperation of the bus differential protection in this situation.

Specifically, in the secondary voltage loop, the load voltage blocking, directional element or exit protection can be switched on or off accordingly according to the corresponding protection function in the current secondary loop. In the secondary current circuit, the busbar differential protection can be blocked accordingly.

The beneficial effect of the present invention is that, compared with the prior art, the method for monitoring the fault of the AC circuit of the protection AC circuit of the protection of the power distribution network by comparing the adjacent nodes in the present invention can detect the voltage of other nodes adjacent to the current node in the protection AC circuit. , current and other electrical quantities are collected, and compared with the corresponding electrical quantities in the current node, thereby optimizing the original fault criterion. The fault criterion in the present invention has simple logic, accurate judgment result and fast response speed, solves the problem of failure of the voltage and current criterion under special circumstances, and ensures the safe and reliable operation of the protection action.

The applicant of the present invention has described and described the embodiments of the present invention in detail with reference to the accompanying drawings, but those skilled in the art should understand that the above embodiments are only preferred embodiments of the present invention, and the detailed description is only to help readers better It should be understood that the spirit of the present invention is not limited to the protection scope of the present invention. On the contrary, any improvement or modification made based on the spirit of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A distribution network protection AC circuit fault monitoring method based on the comparison of adjacent nodes, characterized in that the method comprises the following steps: Step 1: Collect AC operation data of the AC circuit based on the type of AC circuit connected to the current protection node being monitored in the power distribution network; Step 2, collecting the exchange operation data on one or two adjacent protection nodes adjacent to the current protection node; Step 3: Based on the AC operation data of the current protection node collected in the step 1, and the AC operation data on the adjacent protection nodes collected in the step 2, generate a protection AC circuit fault criterion, and based on the The fault criterion adjusts the protection action logic for the protection AC circuit; Wherein, the protection AC circuit fault criterion in the secondary voltage loop including the voltage transformer PT includes a first criterion and a second criterion, and when both the first criterion and the second criterion are satisfied, the The above protection AC circuit fault criterion is established; The first criterion is that the sum of the three-phase AC voltages on the current protection node is greater than a voltage threshold; The second criterion is that the ratio of the sum of the three-phase AC voltages on at least one of the adjacent protection nodes to the sum of the three-phase AC voltages on the current protection node is smaller than the adjacent node difference coefficient. 2. the power distribution network protection AC circuit fault monitoring method based on the comparison of adjacent nodes according to claim 1, is characterized in that: The AC circuit types connected to the current protection node include: a secondary voltage circuit including a voltage transformer PT, and a secondary current circuit including a current transformer CT. 3. the power distribution network protection AC circuit fault monitoring method based on the comparison of adjacent nodes according to claim 2, is characterized in that: Based on the secondary voltage loop including the voltage transformer PT, the collected AC operation data is the three-phase AC voltage output by the voltage transformer PT

and

Based on the secondary current loop including the current transformer CT, the collected AC operation data is the overcurrent state of the three-phase current in the protection node where the current transformer CT is located. 4. the power distribution network protection AC circuit fault monitoring method based on the comparison of adjacent nodes according to claim 3, is characterized in that: If one side of the current protection node has an adjacent protection node, collecting the AC operation data corresponding to the current protection node in the adjacent protection node; If both sides of the current protection node have adjacent protection nodes, collecting the AC operation data corresponding to the current protection node in the two adjacent protection nodes; The AC operation data corresponding to the current protection node is based on the type of AC operation data in the current protection node, and the same type of AC operation data in adjacent protection nodes is collected. 5. The method for monitoring the AC circuit fault of distribution network protection based on the comparison of adjacent nodes according to claim 4, characterized in that: The voltage threshold is determined with reference to the zero-sequence voltage alarm setting value when the secondary circuit of the distribution network is abnormal; The adjacent node difference coefficient is determined based on the ratio of the zero-sequence voltage of each protection node in the power distribution network when the grounded state occurs; Wherein, each protection node includes the current protection node and the adjacent protection node. 6. The method for monitoring the AC circuit fault of power distribution network protection based on the comparison of adjacent nodes according to claim 5, wherein: The voltage threshold is 8V, and the difference coefficient of the adjacent nodes is 0.8. 7. The method for monitoring AC circuit faults of power distribution network protection based on the comparison of adjacent nodes according to claim 4, wherein: The protection AC circuit fault criterion in the secondary current loop including the current transformer CT includes a third criterion and a fourth criterion, and when both the third criterion and the fourth criterion are satisfied, the The above protection AC circuit fault criterion is established; among them, The third criterion is that the busbar differential action criterion on the current protection node is satisfied; The fourth criterion is that the phase where the busbar differential action of the three-phase current on the current protection node is located is different from the phase where the overcurrent state of the three-phase current on each of the adjacent protection nodes is located, and the adjacent protection node is located. The outgoing line overcurrent status on the node is inconsistent. 8. The method for monitoring the AC circuit fault of power distribution network protection based on the comparison of adjacent nodes according to claim 7, wherein: The inconsistency of the phase difference is that any one of the current protection nodes is in which the busbar differential action is located, and the phase difference is not the phase where the overcurrent state of the three-phase current on the adjacent protection node is located, and the phase difference on the adjacent protection node is not. The overcurrent status of the outgoing line is covered by the phase. 9. The AC circuit fault monitoring method for power distribution network protection based on the comparison of adjacent nodes according to claim 7, characterized in that: The differential protection action of each phase in the three-phase busbar differential protection is activated based on the fact that the phase current of the corresponding phase in the protection node is in an overcurrent state. 10. The method for monitoring AC circuit faults of power distribution network protection based on the comparison of adjacent nodes according to claim 1, wherein: When the fault criterion of the secondary voltage circuit is established, an alarm signal of the disconnection of the voltage transformer PT is issued, and the protection function affected by the secondary voltage is correspondingly switched off based on the state of the secondary voltage circuit; When the fault criterion of the secondary current loop is established, the alarm signal of the CT disconnection of the current transformer is issued, and the differential protection of the busbar is blocked.

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