CN108155645A - Closed loop judgment method and device for factory and mine power distribution network - Google Patents

Abstract

The present invention provides a ring closing judgment method and device for power distribution network in factories and mines. The method includes: establishing the external network equivalent model of the ring closing network according to the boundary nodes between the ring closing network and the superior network; The equivalent impedance of the loop-closing network is obtained by model calculation; the steady-state current and transient current of the loop-closing network are calculated according to the voltage difference on both sides of the tie switch and the equivalent impedance of the loop-closing network; When the current is less than the relay protection current threshold and the equipment rated current threshold, it is judged that the power distribution network can close the loop. The present invention can be generally applied to the loop closing operation of various factory and mine power distribution networks, has accurate judgment, reduces the risk of the loop closing operation of factories and mines, avoids unnecessary power outages, and improves the reliability of power supply.

Description

Method and device for judging loop closure of power distribution network in factories and mines

technical field

The invention relates to the field of power distribution in factories and mines, in particular to a method and system for judging the closure of a power distribution network in factories and mines.

Background technique

In order to improve the reliability of power supply in the planning of the power distribution system of factories and mines, the structure of dual power supply or multi-power supply is generally adopted, and the principle of "closed-loop design, open-loop operation" is followed. When a busbar, switch or feeder needs to be repaired or fails, the load powered by multiple power sources on the busbar, switch or feeder needs to be transferred. By operating the contact switch to perform loop closing operation, the power failure time can be reduced and the power supply continuity can be improved. sex. Ring closing operation refers to the operation of converting two or more distribution lines of the same voltage level from radial wiring to ring wiring by closing the tie switch under the condition of ensuring no power failure. If the loop closing operation is performed directly, due to the large voltage difference between the two sides of the contact switch, the initial load of the feeder is heavy, resulting in excessive current after loop closing, causing protection trips, equipment overload, and affecting safe production. Therefore, a ring closure judgment is required before the ring closure.

At present, in the loop closing operation, the voltage amplitude difference between the two sides of the tie switch is generally determined by the voltage transformer, and the voltage phase difference is determined by the nuclear phase detector, and then the test analysis is carried out according to the voltage phase difference and the voltage vector angle to judge whether the loop can be closed . For example, some companies suggest that the difference between the effective value of the voltage on both sides of the contact switch before closing the ring be controlled within 0.3kV, and the voltage phasor angle be controlled within 3 degrees. The disadvantage of this technology is the lack of a reasonable distribution network loop closure analysis model and theoretical derivation, both in qualitative analysis and quantitative analysis are obtained by the test method, the judgment result is not accurate, and limited by the test area, the test The empirical value obtained from the analysis is not universal, and cannot be applied to the loop closing operation of the power distribution network of other factories and mines.

Contents of the invention

The embodiment of the present invention provides a method for judging the loop closure of the power distribution network of factories and mines, which is used to improve the accuracy of the loop closure judgment and improve the reliability of power supply. The method includes:

Establish the external network equivalent model of the ring-closing network according to the boundary nodes between the ring-closing network and the superior network;

Calculate and obtain the equivalent impedance of the ring closing network according to the equivalent model of the external network;

Calculate the steady-state current and transient current of the closed-loop network according to the voltage difference on both sides of the tie switch and the equivalent impedance of the closed-loop network;

When it is determined that the steady-state current and transient current of the closed loop network are less than the relay protection current threshold and the rated current threshold of the equipment, it is judged that the distribution network can close the loop.

The embodiment of the present invention also provides a ring-closing judging device for power distribution network in factories and mines, which is used to improve the accuracy of ring-closing judgment and improve the reliability of power supply. The device includes:

The model building module is used to establish the external network equivalent model of the ring network according to the boundary nodes between the ring network and the superior network;

The equivalent impedance acquisition module is used to calculate and obtain the equivalent impedance of the ring closing network according to the equivalent model of the external network;

The current calculation module is used to calculate the steady-state current and transient current of the closed-loop network according to the voltage difference on both sides of the tie switch and the equivalent impedance of the closed-loop network;

The loop closing judging module judges that the power distribution network can close the loop when it is determined that the steady state current and the transient current of the loop closing network are less than the relay protection current threshold and the equipment rated current threshold.

The embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor. Ring Judgment Method.

The embodiment of the present invention also provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program for executing the method for judging the loop closure of the power distribution network of the factory and mine.

The method for judging the loop closure of the factory and mine power distribution network provided by the embodiment of the present invention first needs to establish an equivalent model of the external network of the loop closure network to obtain the equivalent impedance of the external network, and then obtain the loop closure network according to the voltage difference on both sides of the tie switch The transient current and steady-state current; finally judge whether the loop-closing operation can be performed according to the steady-state current and transient current of the loop-closing network. The loop closure judgment method of the power distribution network of factories and mines according to the embodiment of the present invention is judged based on the current of the loop closure network. It reduces the risk of closed-loop operation of factories and mines, avoids unnecessary power outages, and improves the reliability of power supply.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work. In the attached picture:

Fig. 1 is the schematic flow chart of the loop closing judgment method of power distribution network in factories and mines in the embodiment of the present invention;

Fig. 2 is a schematic diagram of the principle of ring closure judgment in an embodiment of the present invention;

FIG. 3 is a schematic diagram of the division of an internal network and an external network in an embodiment of the present invention;

Fig. 4 is a schematic diagram of a balance node in an embodiment of the present invention;

Fig. 5a, Fig. 5b are the schematic diagrams of obtaining the steady-state current of the ring closing network in the embodiment of the present invention;

6 is a schematic diagram of an equivalent circuit for calculating the transient current of the ring closing network in an embodiment of the present invention;

Fig. 7 is a schematic structural diagram of a ring closure judging device of a power distribution network in a factory and a mine according to an embodiment of the present invention;

Fig. 8 is a schematic structural diagram of an equivalent impedance acquisition module in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

When the loop closing operation is performed in the enterprise, the failure is mainly due to the action of the relay protection device, which trips a certain incoming line circuit breaker, and all the loads carried by the two bus sections of the loop closing lose power. The relay protection action is mainly due to the large loop closing current generated by the loop closing operation, which causes the protection action. While the large closed loop current causes protection action, it is often accompanied by overload of the main transformer and current-carrying conductors, which poses a greater threat to system safety. Therefore, the inventor believes that when judging whether the loop closing operation is successful, it is first necessary to calculate the loop closing current, and then judge whether the loop closing operation can be performed according to the loop closing current.

Based on the above reasons, the embodiment of the present invention provides a method for judging the loop closure of the power distribution network of factories and mines, which is used to improve the accuracy of the loop closure judgment and improve the reliability of power supply. As shown in Figure 1, the method includes:

101: Establish an external network equivalent model of the ring-closed network according to the boundary nodes between the ring-closed network and the upper-level network;

102: Calculate and obtain the equivalent impedance of the loop closing network according to the equivalent model of the external network;

103: Calculate the steady-state current and transient current of the loop-closing network according to the voltage difference on both sides of the tie switch and the equivalent impedance of the loop-closing network;

104: When it is determined that the steady-state current and the transient current of the loop-closing network are less than the relay protection current threshold and the rated current threshold of the equipment, determine that the power distribution network can be loop-closed.

In one embodiment, when it is determined that the steady-state current and transient current of the ring-closing network are less than the relay protection current threshold and the rated current threshold of the equipment, it is judged that the power distribution network can be closed. There can be various implementations, for example , as shown in Figure 2, it can be judged that the distribution network can be closed when the steady-state current and transient current of the closed-loop network meet the following conditions:

I> _dz >I _c ;

I ≥ _dz > I _im ;

I _TR.e >I _c ;

Among them, I> _dz represents the overcurrent setting value of the relay protection device, _I≥dz represents the quick tripping value of the relay protection device, I _TR.e represents the overload capacity of the transformer, I _c represents the steady-state current, I _im represents the temporary state current.

In one embodiment, as shown in FIG. 2 , if the ring closing cannot be performed directly, the parameters of the ring closing network can also be adjusted until the ring closing operation can be performed. There are various implementation schemes for adjusting the parameters of the loop closing network. For example, when the steady-state current and transient current of the loop closing network are determined not to be less than the relay protection current threshold and the rated current threshold of the equipment, adjust the voltage on both sides of the tie switch According to the adjusted voltage difference, recalculate the steady-state current and transient current of the loop-closing network until the steady-state current and transient current of the loop-closing network are less than the relay protection current threshold and the rated current threshold of the equipment, and judge the power distribution The network can close the loop. After judging that the ring can be closed, an instruction to allow ring closing can also be issued. If the loop is still not closed after adjusting the parameters, you can issue a command that does not allow the loop to close.

In one embodiment, there may be multiple real-time ways to calculate and obtain the equivalent impedance of the ring-closing network according to the equivalent model of the external network. The injected power obtains the equivalent impedance of the closed loop network. During the implementation, due to the complexity of the external network and the possibility of changes, it is difficult for the electrical room performing the loop closure operation to obtain the parameters of the external network. To solve this problem, the improved Ward equivalent method can be used to perform the equivalent of the external network. The specific method is as follows:

As shown in Figure 3, there are only one or two boundary nodes between the 10kV ring closing network of factories and mines and the upper-level network. In order to meet the calculation requirements, we use the bus to be closed as the boundary bus, the boundary bus and the internal network (system ) as a research system, the outside of the boundary bus is the external network. The connection branch between the internal network (system) and the boundary bus becomes the tie line. Subset A represents the internal network, subset B is the set of boundary nodes (boundary buses), and subset C is the set of external nodes. The electrical connection of the system can be expressed by the following linear equation:

Among them, Y represents the self-admittance of each node and the mutual admittance between nodes, U represents the voltage of each node, I represents the injection current of each node, C represents the external node, B represents the boundary node, and A represents the internal node;

Eliminate the external nodes in the above formula, that is, eliminate U _C , the following equation can be obtained:

In practical applications, power can be used instead of current, and the equation is transformed into:

if will be defined as:

Then formula (2) can be written as:

Among them, _EY ^EQ is the injected power of the external network; U _B is the voltage of the boundary node; U _A is the voltage of the closed ring network; U _C is the voltage of the external network; S _B is the power of the boundary node; Power; S _C is the power of the external network; Y _BC is the mutual admittance between the external network and the boundary nodes; Y _CC is the self-admittance of the external network;

If the node voltage is known, the injected power of the external network is allocated to the incremental value of the injected power on the boundary node for:

The external network injection power can be calculated by the following formula:

Among them, S ₁ , S ₂ , and S _R represent the node injection power, y ₁ , y ₂ , and y _R represent the admittance of the branch, and Y _B12 is the admittance value of the equivalent branch between nodes on both sides of the equivalent network; S _eq1 and S _eq2 are the injection power calculated by the above formula (5) when the two boundary nodes are in the basic state, S _B12 is the power of the equivalent branch between the two boundary nodes of Ward equivalent value, and S _t1 and S _t2 are the real-time measurement to be combined The link power of the ring.

As shown in Figure 4, the equivalent impedance of the loop-closing network is viewed from the loop-closing port, and traced from the loop-closing point to the power point, that is, the sum of the impedances of the balanced nodes, and R is the balanced node.

B1 and B2 in the figure represent two boundary nodes, and the power of the balance node is:

The voltages of the two boundary nodes are U ₁ and U ₂ , which can be obtained from the measured data of the ring closure system, so the voltage _UR of the balanced node can be obtained:

Then calculate the admittance y _R of the balance node and the admittance y _i of the ring-closing network branches:

Finally, the equivalent impedance Z _eq of the ring closing network is calculated according to the following formula:

Among them, Z _eq is the equivalent impedance of the closed loop network; S _i is the power of the boundary node; y ₁ , y ₂ , y _i are the admittances of the branches of the closed loop network; U _i is the voltage of the boundary node.

In one embodiment, since the size of the loop closing current is related to the voltage difference on both sides of the tie switch and the equivalent impedance of the loop closing network, after measuring the voltage difference on both sides of the tie switch and calculating the equivalent impedance of the loop closing network, you can Calculate and obtain the steady-state current and transient current of the loop-closing network. According to the voltage difference on both sides of the tie switch and the equivalent impedance of the external network, there are many ways to calculate the steady-state current and transient current of the closed-loop network, for example, it may include:

As shown in Figure 5a and Figure 5b, the network in the figure can be decomposed into two networks, one is a radial network (Figure 5a) and the other is a ring network (Figure 5b). Perform calculations, and superimpose the calculated results to obtain the steady-state current of the entire network. There are many implementations for obtaining the steady-state current. For example, the steady-state current can be calculated according to the following formula:

Among them, I _c is the steady-state current of the closed loop network; U _oc is the voltage difference on both sides of the tie switch; Z _eq is the equivalent impedance of the closed loop network;

There can be multiple implementations for obtaining the transient current of the loop closing network. For example, as shown in Figure 6, after the loop closing, the differential equation of the loop closing network is as follows:

Among them, E _m represents the electric potential; R represents the resistance of the equivalent impedance of the ring-closing network, and L represents the inductance of the equivalent impedance of the ring-closing network;

After solving the differential equation, the transient current is calculated according to the following formula:

Among them, I _im is the transient current of the closed loop network; T _a is the time constant; I _ct is the steady state current of the closed loop network.

Based on the same inventive concept, an embodiment of the present invention also provides a device for judging loop closure of a power distribution network in factories and mines, as described in the following embodiments. Since the problem-solving principle of the loop-closing judgment device of the power distribution network of factories and mines is similar to the method of judging the loop-closing of power distribution networks of factories and mines, the implementation of the judging device of loop-closing of power distribution networks of factories and mines can be referred to in the section of the judging method of loop-closing of power distribution networks of factories and mines. implementation, the repetition will not be repeated.

Fig. 7 is a loop closure judging device of the factory and mine power distribution network according to the embodiment of the present invention. As shown in Figure 7, the ring closure judging device of the factory and mine power distribution network of the embodiment of the present invention comprises:

The model building module 701 is used to establish the external network equivalent model of the ring-closing network according to the boundary nodes between the ring-closing network and the superior network;

Equivalent impedance acquisition module 702, used to calculate and obtain the equivalent impedance of the ring closing network according to the equivalent model of the external network;

The current calculation module 703 is used to calculate the steady-state current and transient current of the loop-closing network according to the voltage difference on both sides of the tie switch and the equivalent impedance of the loop-closing network;

The loop closing judging module 704 is used to determine that the power distribution network can close the loop when it is determined that the steady state current and the transient current of the loop closing network are less than the relay protection current threshold and the rated current threshold of the equipment.

In one embodiment, the loop closure judgment module is further used for:

When it is determined that the steady-state current and transient current of the closed-loop network are not less than the relay protection current threshold and the rated current threshold of the equipment, adjust the voltage difference on both sides of the contact switch, and recalculate the stable loop-closed network according to the adjusted voltage difference. State current and transient current, until the steady state current and transient current of the ring closing network are less than the relay protection current threshold and the rated current threshold of the equipment, it can be judged that the power distribution network can close the loop.

In one embodiment, as shown in Figure 8, the equivalent impedance acquisition module further includes:

The injection power acquisition sub-module 801 is used to calculate and obtain the injection power of the external network according to the external network equivalent model of the ring closing network;

The impedance obtaining sub-module 802 is used to obtain the equivalent impedance of the loop closing network according to the injected power of the external network.

In one embodiment, the injection power acquisition sub-module is calculated according to the following formula:

Among them, _EY ^EQ is the injected power of the external network; U _B is the voltage of the boundary node; U _A is the voltage of the closed ring network; U _C is the voltage of the external network; S _B is the power of the boundary node; Power; S _C is the power of the external network; Y _BC is the mutual admittance between the external network and the boundary nodes; Y _CC is the self-admittance of the external network;

The impedance acquisition sub-module is calculated according to the following formula:

Among them, Z _eq is the equivalent impedance of the closed loop network; S _i is the power of the boundary node; y ₁ , y ₂ , y _i are the admittances of the branches of the closed loop network; U _i is the voltage of the boundary node.

In one embodiment, the current calculation module,

include:

The steady state current is calculated according to the following formula:

Among them, I _c is the steady-state current of the closed loop network; U _oc is the voltage difference on both sides of the tie switch; Z _eq is the equivalent impedance of the closed loop network;

Calculate the transient current according to the following formula:

Among them, I _im is the transient current of the closed loop network; T _a is the time constant; I _ct is the steady state current of the closed loop network.

The embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor. Ring Judgment Method.

The embodiment of the present invention also provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program for executing the method for judging the loop closure of the power distribution network of the factory and mine.

To sum up, the method for judging the loop closure of the factory and mine power distribution network provided by the embodiment of the present invention first needs to establish an equivalent model of the external network of the loop closure network to obtain the equivalent impedance of the external network, and then according to the voltage on both sides of the tie switch The difference between the transient current and the steady current of the loop closing network is obtained; finally, it is judged whether the loop closing operation can be performed according to the steady current and transient current of the loop closing network. The loop closure judgment method of the power distribution network of factories and mines according to the embodiment of the present invention is judged based on the current of the loop closure network. It reduces the risk of closed-loop operation of factories and mines, avoids unnecessary power outages, and improves the reliability of power supply.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (12)

1. A method for judging the closure of power distribution networks in factories and mines, characterized in that it comprises: Establish the external network equivalent model of the ring-closing network according to the boundary nodes between the ring-closing network and the superior network; Calculate and obtain the equivalent impedance of the ring closing network according to the equivalent model of the external network; Calculate the steady-state current and transient current of the closed-loop network according to the voltage difference on both sides of the tie switch and the equivalent impedance of the closed-loop network; When it is determined that the steady-state current and transient current of the closed loop network are less than the relay protection current threshold and the rated current threshold of the equipment, it is judged that the distribution network can close the loop. 2. the loop closure judgment method of power distribution network in factories and mines as claimed in claim 1, is characterized in that, further comprises: When it is determined that the steady-state current and transient current of the closed-loop network are not less than the relay protection current threshold and the rated current threshold of the equipment, adjust the voltage difference on both sides of the contact switch, and recalculate the stable loop-closed network according to the adjusted voltage difference. State current and transient current, until the steady state current and transient current of the ring closing network are less than the relay protection current threshold and the rated current threshold of the equipment, it can be judged that the power distribution network can close the loop. 3. the method for judging the ring closing of the power distribution network of factories and mines as claimed in claim 1 or 2, is characterized in that, said calculation obtains the equivalent impedance of the ring closing network according to the external network equivalent model, comprising: Calculate and obtain the injection power of the external network according to the external network equivalent model of the closed ring network; The equivalent impedance of the loop closing network is obtained according to the injected power of the external network. 4. the method for judging the ring closing of power distribution network of factories and mines as claimed in claim 3, is characterized in that, described according to the external network equivalent model of ring closing network, calculates and obtains external network injection power, calculates according to following formula: Among them, _EY ^EQ is the injected power of the external network; U _B is the voltage of the boundary node; U _A is the voltage of the closed ring network; U _C is the voltage of the external network; S _B is the power of the boundary node; Power; S _C is the power of the external network; Y _BC is the mutual admittance between the external network and the boundary nodes; Y _CC is the self-admittance of the external network; The equivalent impedance of the ring closing network is obtained according to the injection power of the external network, and is calculated according to the following formula: Among them, Z _eq is the equivalent impedance of the closed loop network; S _i is the power of the boundary node; y ₁ , y ₂ , y _i are the admittances of the branches of the closed loop network; U _i is the voltage of the boundary node. 5. the loop-closing judging method of power distribution network in factories and mines as claimed in claim 4, is characterized in that, described steady-state current and the transient state of loop-closing network are calculated according to the voltage difference on both sides of tie switch and the equivalent impedance of external network current, including: The steady state current is calculated according to the following formula: Among them, I _c is the steady-state current of the closed loop network; U _oc is the voltage difference on both sides of the tie switch; Z _eq is the equivalent impedance of the closed loop network; Calculate the transient current according to the following formula: Among them, I _im is the transient current of the closed loop network; T _a is the time constant; I _ct is the steady state current of the closed loop network. 6. A ring closure judgment device for power distribution network in factories and mines, characterized in that it comprises: The model building module is used to establish the external network equivalent model of the ring network according to the boundary nodes between the ring network and the superior network; The equivalent impedance acquisition module is used to calculate and obtain the equivalent impedance of the ring closing network according to the equivalent model of the external network; The current calculation module is used to calculate the steady-state current and transient current of the closed-loop network according to the voltage difference on both sides of the tie switch and the equivalent impedance of the closed-loop network; The loop closing judging module is used to determine that the power distribution network can close the loop when it is determined that the steady state current and the transient current of the loop closing network are less than the relay protection current threshold and the rated current threshold of the equipment. 7. the ring closure judging device of power distribution network in factories and mines as claimed in claim 6, is characterized in that, described ring closure judgment module is further used for: When it is determined that the steady-state current and transient current of the closed-loop network are not less than the relay protection current threshold and the rated current threshold of the equipment, adjust the voltage difference on both sides of the contact switch, and recalculate the stable loop-closed network according to the adjusted voltage difference. State current and transient current, until the steady state current and transient current of the ring closing network are less than the relay protection current threshold and the rated current threshold of the equipment, it can be judged that the power distribution network can close the loop. 8. The ring-closing judging device of the power distribution network of factories and mines as claimed in claim 6 or 7, is characterized in that, said equivalent impedance acquisition module further comprises: The injection power acquisition sub-module is used to calculate and obtain the injection power of the external network according to the external network equivalent model of the ring closing network; The impedance obtaining sub-module is used to obtain the equivalent impedance of the loop closing network according to the injected power of the external network. 9. the ring closure judging device of power distribution network in factories and mines as claimed in claim 8, is characterized in that, described injection power obtains sub-module, calculates according to the following formula: Among them, _EY ^EQ is the injected power of the external network; U _B is the voltage of the boundary node; U _A is the voltage of the closed ring network; U _C is the voltage of the external network; S _B is the power of the boundary node; Power; S _C is the power of the external network; Y _BC is the mutual admittance between the external network and the boundary nodes; Y _CC is the self-admittance of the external network; The impedance acquisition sub-module is calculated according to the following formula: Among them, Z _eq is the equivalent impedance of the closed loop network; S _i is the power of the boundary node; y ₁ , y ₂ , y _i are the admittances of the branches of the closed loop network; U _i is the voltage of the boundary node. 10. The ring closure judging device of the power distribution network of factories and mines as claimed in claim 9, wherein the current calculation module comprises: The steady state current is calculated according to the following formula: Among them, I _c is the steady-state current of the closed loop network; U _oc is the voltage difference on both sides of the tie switch; Z _eq is the equivalent impedance of the closed loop network; Calculate the transient current according to the following formula: Among them, I _im is the transient current of the closed loop network; T _a is the time constant; I _ct is the steady state current of the closed loop network. 11. A computer device, comprising a memory, a processor, and a computer program stored on the memory and operable on the processor, characterized in that, when the processor executes the computer program, any one of claims 1 to 5 is realized. the method. 12. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing the method according to any one of claims 1 to 5.