System and method for reducing current and improving electric energy quality

Abstract

The invention relates to the field of current reducing systems, and particularly discloses a system and a method for reducing current and improving electric energy quality, comprising at least one current limiting module, a first current transformer, at least one capacitive module, a first switch, a second switch, a third switch, a fourth switch, a control protection system and a voltage transformer, the current limiting module is connected in series with the third switch, then connected in parallel with the fourth switch, and then integrally connected in series with the first current transformer; the capacitive module is connected in series with the second switch and then connected in parallel with the third switch; one end of the first switch is connected with the capacitive module and a connecting line of the second switch, and the other end of the first switch is grounded. Functions of current limiting, reactive compensation, series compensation, harmonic filtering and the like can be realized, and the number of equipment is reduced.

Description

Technical Field

[0001] The present invention specifically relates to the field of current reduction systems, and more specifically, to a system and method for reducing current and improving power quality. Background Art

[0002] With the improvement of the requirements for power supply reliability and the increasing power consumption capacity, the grid structure is becoming more and more complex, and the problem of excessive short-circuit current is becoming more prominent. Excessive short-circuit current will cause the circuit breaker to be unable to cut off the fault circuit during a fault, seriously affecting the safety of the power system. Connecting a fault current limiter in the line is a better solution to the problem of excessive fault current. Among them, the fast-switching type fault current limiter is a mature application solution. When applied in a high-voltage system, the usual solution is to connect multiple fast switches in series and then connect a shunt reactor in parallel. At this time, each fast switch needs to be connected in parallel with a large-capacity voltage-sharing capacitor to ensure voltage sharing at the break. However, the reliability requirements and costs of large-capacity voltage-sharing capacitors are relatively high, and only relative voltage sharing can be achieved. After a single break fails, the function of the current limiter fails, and the value of the shunt inductance inserted into the line cannot be flexibly adjusted during a fault.

[0003] When there are many inductive loads in the power grid, the power factor does not meet the requirements, the active power transmission capacity of long lines is small, and the harmonic components caused by power electronic devices in the power grid are prominent. It is necessary to configure reactive power compensation, series compensation, harmonic filtering and other devices to solve the above problems, resulting in a large number of devices configured in the power grid. Summary of the Invention

[0004] The purpose of the present invention is to provide a system and method for reducing current and improving power quality to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A system for reducing current and improving power quality includes at least one current limiting module, a first current transformer, at least one capacitive module, a first switch, a second switch, a third switch, a fourth switch, a control and protection system, and a voltage transformer, wherein:

[0007] The current limiting module is connected in series with the third switch and then connected in parallel with the fourth switch, and then the whole is connected in series with the first current transformer; the capacitive module is connected in series with the second switch and then connected in parallel with the third switch; one end of the first switch is connected to the connection line between the capacitive module and the second switch, and the other end of the first switch is grounded.

[0008] The control and protection system is used to obtain the measurement values of the first current transformer and the voltage transformer, as well as the telemetry and remote measurement of the current limiting module and the capacitive module, and send the remote control quantity to the current limiting module and the capacitive module.

[0009] The first current transformer, the current limiting module, and the third switch are connected to form a series circuit. One end of the voltage transformer is connected to this series circuit, and the other end of the voltage transformer is grounded.

[0010] The current limiting module includes a fast switch, a reactor, and a second current transformer. The reactor and the second current transformer are connected in series and then connected in parallel with the fast switch;

[0011] The capacitive module includes a fifth switch and a capacitor. The fifth switch and the capacitor are connected in series.

[0012] As a further solution of the present invention: The system for reducing current and improving power quality has multiple operating modes, and the operating modes include a current limiting mode, a reactive power compensation mode, a series compensation mode, and a harmonic filtering mode.

[0013] As a further solution of the present invention: When the system for reducing current and improving power quality operates in the current limiting mode, the fast switch and the third switch are in the closed position, and the first switch, the second switch, the fourth switch, and the fifth switch are in the open position.

[0014] As a further solution of the present invention: When the system for reducing current and improving power quality operates in the reactive power compensation mode, the first switch, the third switch, and the fast switch are in the closed position, and the second switch and the fourth switch are in the open position.

[0015] As a further solution of the present invention: When the system for reducing current and improving power quality operates in the series compensation mode, the second switch and the fast switch are in the closed position, and the first switch, the third switch, and the fourth switch are in the open position.

[0016] As a further solution of the present invention: When the system for reducing current and improving power quality operates in the harmonic filtering mode, the first switch and the fourth switch are in the closed position, and the second switch and the third switch are in the open position.

[0017] A method for reducing current. When the system for reducing current and improving power quality operates in the current limiting mode, it includes the following steps:

[0018] S101: Close the fast switch and the third switch, and open the first switch, the second switch, the fourth switch, and the fifth switch;

[0019] S102: When the current collected by the first current transformer exceeds the fault current setting value, control the protection system to calculate the number of reactors to be put into operation according to the setting value, and control the corresponding number of fast switches to open, while the remaining fast switches remain closed. Limit the fault current by connecting the reactors in series to the line;

[0020] S103. After a delay longer than the setting time of the system backup protection, the control and protection system sends a reclosing command to the fast switch in the open state. After the reclosing command ends, if the current detected by the second current transformer is [value], the system operation ends; if the second current transformer still detects current, the control and protection system sends a reclosing command to the fast switch of the current limiting module corresponding to the second current transformer again; if the second current transformer detects current as [value], the system operation ends; if the second current transformer still detects current, then step S104 is executed;

[0021] S104. Close the fourth switch and generate an alarm of "abnormal closing of the current limiting fast switch"

[0022] As a further solution of the present invention: when the system for reducing current and improving power quality operates in the reactive power compensation mode, it includes the following steps:

[0023] S201. Close the first switch, the third switch and the fast switch, and open the second switch and the fourth switch;

[0024] S202. The control and protection system calculates the system reactive power compensation demand according to the power factor requirement and the remote measurement values of the first current transformer and the voltage transformer collected;

[0025] S203. The control and protection system calculates the number of capacitive modules to be put into operation, closes the fifth switch of the capacitive modules to be put into operation, and the fifth switches of the remaining capacitive modules are in the open state.

[0026] As a further solution of the present invention: when the system for reducing current and improving power quality operates in the series compensation mode, it includes the following steps:

[0027] S301. Close the second switch and the fast switch, and open the first switch, the third switch and the fourth switch;

[0028] S302. The control and protection system calculates the number of capacitive modules to be put into operation according to the line active power transmission capacity requirement and the remote measurement values of the first current transformer and the voltage transformer collected, closes the fifth switch of the capacitive modules to be put into operation, and the fifth switches of the remaining capacitive modules are in the open state.

[0029] As a further solution of the present invention: when the system for reducing current and improving power quality operates in the harmonic filtering mode, it includes the following steps:

[0030] S401. Close the first switch and the fourth switch, and open the second switch and the third switch;

[0031] S402. The control and protection system analyzes the harmonic components and the harmonic orders to be filtered based on the remotely measured values collected from the voltage transformers, calculates and obtains the series connection scheme of inductors and capacitors, and closes the fast switches of the current-limiting modules to be put into operation and the fifth switches of the capacitive modules.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention realizes functions such as current limiting, reactive power compensation, series compensation, and harmonic filtering through switch switching, effectively reducing the number of grid equipment.

[0034] 2. Each fast circuit breaker in the present invention is connected in parallel with a reactor, eliminating the need to configure voltage-sharing capacitors. The single-break fault current-limiting function does not fail, and the number of reactors that can be flexibly connected in series during a fault can reach different current-limiting depths.

[0035] 3. After the fast switch in the current-limiting module of the present invention receives the reclosing signal, it additionally detects the current value of the second CT, which can prevent the fast switch from actually failing to close successfully after receiving the reclosing signal, resulting in the long-term flow of current through the current-limiting reactor and causing a burnout fault. The current-limiting reactor can only withstand short-time fault currents and operating currents and cannot withstand long-term operating currents. If the fast switch still fails to close successfully after receiving the second reclosing signal, it is highly likely that the fast switch is damaged. At this time, the fourth switch is closed, and an alarm of "abnormal closing of the current-limiting fast switch" is generated, which can effectively ensure the safety of the equipment, and the power grid system can continue to operate normally. The maintenance work of the fast switch can be carried out after there is a maintenance window.

[0036] 4. The control and protection system in the present invention calculates the number of reactors to be put into operation according to the setting values, controls the opening of the corresponding number of fast switches, and the remaining fast switches remain closed. The control and protection system calculates the number of capacitive modules to be put into operation and closes the fifth switches of the capacitive modules to be put into operation, while the fifth switches of the remaining capacitive modules are in the off position. The control and protection system calculates and obtains the series connection scheme of inductors and capacitors, and closes the fast switches of the current-limiting modules and the fifth switches of the capacitive modules to be put into operation. By flexibly putting into operation the number of reactors and capacitors, the number of switch operations can be reduced, the operation times of the reactors and capacitors can be decreased, and the product life can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a system topology diagram for reducing current and improving power quality provided by an embodiment of the present invention;

[0038] Figure 2 It is a topology diagram of a current reduction system operating in a current-limiting mode provided by an embodiment of the present invention;

[0039] Figure 3 It is an operating logic of a current reduction system operating in a current-limiting mode provided by an embodiment of the present invention;

[0040] Figure 4 A topology diagram of a current reduction system operating in a reactive power compensation mode provided by an embodiment of the present invention;

[0041] Figure 5 A topology diagram of a current reduction system operating in a series compensation mode provided by an embodiment of the present invention;

[0042] Figure 6 A topology diagram of a current reduction system operating in a harmonic filtering mode provided by an embodiment of the present invention.

[0043] In the figure: 1 - current limiting module, 11 - fast switch, 12 - reactor, 13 - second current transformer, 2 - first current transformer, 3 - capacitive module, 31 - fifth switch, 32 - capacitor, 4 - first switch, 5 - second switch, 6 - third switch, 7 - fourth switch, 8 - control and protection system, 9 - voltage transformer. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] Please refer to Figure 1 , in an embodiment of the present invention, a system for reducing current and improving power quality includes at least one current limiting module 1, a first current transformer 2, at least one capacitive module 3, a first switch 4, a second switch 5, a third switch 6, a fourth switch 7, a control and protection system 8, and a voltage transformer 9, wherein:

[0046] The current limiting module 1 is connected in series with the third switch 6 and then in parallel with the fourth switch 7, and then the whole is connected in series with the first current transformer 2; the capacitive module 3 is connected in series with the second switch 5 and then in parallel with the third switch 6; one end of the first switch 4 is connected to the connection line of the capacitive module 3 and the second switch 5, and the other end of the first switch 4 is grounded.

[0047] The control and protection system 8 is used to obtain the measurement values of the first current transformer 2 and the voltage transformer 9, as well as the telemetry and remote measurement of the current limiting module 1 and the capacitive module 3, and send the remote control quantity to the current limiting module 1 and the capacitive module 3.

[0048] The first current transformer 2, the current limiting module 1, and the third switch 6 are connected to form a series circuit. One end of the voltage transformer 9 is connected to this series circuit, and the other end of the voltage transformer 9 is grounded.

[0049] Further, in the embodiment of the present application, the current limiting module 1 includes a fast switch 11, a reactor 12, and a second current transformer 13. The reactor 12 and the second current transformer 13 are connected in series and then connected in parallel with the fast switch 11. When the number of the current limiting modules 1 is greater than one, multiple current limiting modules 1 are connected in series.

[0050] In the embodiment of the present application, the capacitive module 3 includes a fifth switch 31 and a capacitor 32. The fifth switch 31 and the capacitor 32 are connected in series. When the number of the capacitive modules 3 is greater than one, multiple capacitive modules 3 are connected in parallel.

[0051] In the embodiment of the present application, the system for reducing current and improving power quality has multiple operating modes. In this embodiment, the operating modes include a current limiting mode, a reactive power compensation mode, a series compensation mode, and a harmonic filtering mode, where:

[0052] As Figure 2 shown, when the system for reducing current and improving power quality operates in the current limiting mode, the fast switch 11 and the third switch 6 are in the closed position, and the first switch 4, the second switch 5, the fourth switch 7, and the fifth switch 31 are in the open position.

[0053] As Figure 4 shown, when the system for reducing current and improving power quality operates in the reactive power compensation mode, the first switch 4, the third switch 6, and the fast switch 11 are in the closed position, and the second switch 5 and the fourth switch 7 are in the open position.

[0054] As Figure 5 shown, when the system for reducing current and improving power quality operates in the series compensation mode, the second switch 5 and the fast switch 11 are in the closed position, and the first switch 4, the third switch 6, and the fourth switch 7 are in the open position.

[0055] As Figure 6 shown, when the system for reducing current and improving power quality operates in the harmonic filtering mode, the first switch 4 and the fourth switch 7 are in the closed position, and the second switch 5 and the third switch 6 are in the open position.

[0056] In summary, the system for reducing current and improving power quality realizes functions such as current limiting, reactive power compensation, series compensation, and harmonic filtering through switch switching, effectively reducing the number of grid equipment. Each fast circuit breaker is connected in parallel with a reactor, eliminating the need to configure voltage equalizing capacitors, ensuring that the single - break fault current limiting function does not fail, and enabling flexible connection of the number of reactors during faults to achieve different current limiting depths.

[0057] As Figure 3 shown, this embodiment discloses a method for reducing current. When the system for reducing current and improving power quality operates in the current limiting mode, it includes the following steps:

[0058] S101. Close the fast switch 11 and the third switch 6, and open the first switch 4, the second switch 5, the fourth switch 7, and the fifth switch 31.

[0059] S102. When the current collected by the first current transformer 2 exceeds the fault current setting value, control the protection system 8 to calculate the number of reactors 12 to be put into operation according to the setting value, and control the corresponding number of fast switches 11 to open, while the remaining fast switches 11 remain closed. By connecting the reactors 12 in series in the line, the fault current is limited.

[0060] S103. After a delay longer than the system backup protection setting time, control the protection system 8 to send a reclosing command to the fast switches 11 in the open state. After the reclosing command ends, if the current detected by the second current transformer 13 is 0, the system operation ends; if the second current transformer 13 still detects current, control the protection system 8 to send a reclosing command to the fast switches 11 of the current limiting module 1 corresponding to the second current transformer 13 again; if the second current transformer 13 detects that the current is 0, the system operation ends; if the second current transformer 13 still detects current, then execute step S104.

[0061] S104. Close the fourth switch 7 and generate an alarm of "abnormal closing of the current limiting fast switch".

[0062] The protection system 8 calculates the number of reactors to be put into operation according to the setting value, controls the corresponding number of fast switches to open, and the remaining fast switches remain closed. Flexibly putting in the number of reactors can reduce the number of switch operations, reduce the number of reactor operations, and improve the product life. After the fast switch in the current limiting module receives the reclosing signal, detecting the current value of the second current transformer is increased, which can prevent the fast switch from actually failing to close successfully after receiving the reclosing signal, resulting in the long-term flow of current through the current limiting reactor and causing a burnout fault. The current limiting reactor can only withstand short-term fault current and operating current, and cannot withstand long-term operating current. If the fast switch still fails to close successfully after receiving the reclosing signal twice, it is very likely that the fast switch is damaged. At this time, closing the fourth switch and generating an alarm of "abnormal closing of the current limiting fast switch" can effectively ensure the safety of the equipment, and the power grid system can continue to operate normally, and then perform the maintenance work of the fast switch after there is a maintenance window.

[0063] As Figure 4 shown, this embodiment also discloses a method for reducing current. When the system for reducing current and improving power quality operates in the reactive power compensation mode, it includes the following steps:

[0064] S201. Close the first switch 4, the third switch 6, and the fast switch 11, and open the second switch 5 and the fourth switch 7.

[0065] S202. The control and protection system 8 calculates the reactive power compensation requirement of the system according to the power factor requirement and the remote measurements of the first current transformer 2 and the voltage transformer 9 collected.

[0066] S203. The control and protection system 8 calculates the number of capacitive modules 3 to be put into operation, closes the fifth switches 31 of the capacitive modules 3 to be put into operation, and the fifth switches 31 of the remaining capacitive modules 3 are in the off position.

[0067] The control and protection system 8 calculates the number of capacitive modules to be put into operation, closes the fifth switches of the capacitive modules to be put into operation, and the fifth switches of the remaining capacitive modules are in the off position. Flexibly putting into operation the number of capacitors can reduce the number of switch operations, reduce the number of capacitor operations, and improve the product life.

[0068] As Figure 5 shown, this embodiment also discloses a method for reducing current. When the system for reducing current and improving power quality operates in the series compensation mode, it includes the following steps:

[0069] S301. Close the second switch 5 and the fast switch 11, and open the first switch 4, the third switch 6, and the fourth switch 7.

[0070] S302. The control and protection system 8 calculates the number of capacitive modules 3 to be put into operation according to the line active power transmission capacity requirement and the remote measurements of the first current transformer 2 and the voltage transformer 9 collected, closes the fifth switches 31 of the capacitive modules 3 to be put into operation, and the fifth switches 31 of the remaining capacitive modules 3 are in the off position.

[0071] The control and protection system 8 calculates the number of capacitive modules to be put into operation, closes the fifth switches of the capacitive modules to be put into operation, and the fifth switches of the remaining capacitive modules are in the off position. Flexibly putting into operation the number of capacitors can reduce the number of switch operations, reduce the number of capacitor operations, and improve the product life.

[0072] As Figure 6 shown, this embodiment also discloses a method for reducing current. When the system for reducing current and improving power quality operates in the harmonic filtering mode, it includes the following steps:

[0073] S401. Close the first switch 4 and the fourth switch 7, and open the second switch 5 and the third switch 6.

[0074] S402. The control and protection system 8 analyzes the harmonic components and the harmonic orders to be filtered according to the remote measurements of the voltage transformer 9 collected, calculates and obtains the series scheme of inductance and capacitance, and closes the fast switches 11 of the current limiting modules 1 and the fifth switches 31 of the capacitive modules 3 to be put into operation.

[0075] The control and protection system 8 calculates and obtains the series scheme of inductance and capacitance, and closes the fast switch of the current-limiting module to be put into operation and the fifth switch of the capacitive module. The number of reactors and capacitors can be flexibly put into operation, which can reduce the number of switch operations, reduce the operation times of reactors and capacitors, and improve the product life.

[0076] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0077] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for reducing current and improving power quality, characterized in that: The invention comprises at least one current limiting module (1), a first current transformer (2), at least one capacitive module (3), a first switch (4), a second switch (5), a third switch (6), a fourth switch (7), a control and protection system (8) and a voltage transformer (9), wherein: The current limiting module (1) is connected in series with the third switch (6) and then in parallel with the fourth switch (7), and then the whole is connected in series with the first current transformer (2); the capacitive module (3) is connected in series with the second switch (5) and then in parallel with the third switch (6); one end of the first switch (4) is connected to the connecting line of the capacitive module (3) and the second switch (5), and the other end of the first switch (4) is grounded. The control and protection system (8) is used to obtain the measurement values ​​of the first current transformer (2) and the voltage transformer (9) and the remote signaling and remote measurement values ​​of the current limiting module (1) and the capacitive module (3), and to send the remote control values ​​to the current limiting module (1) and the capacitive module (3). The first current transformer (2), the current limiting module (1) and the third switch (6) are connected to form a series circuit, one end of the voltage transformer (9) is connected to the series circuit, and the other end of the voltage transformer (9) is grounded. The current limiting module (1) comprises a fast switch (11), a reactor (12) and a second current transformer (13); the reactor (12) and the second current transformer (13) are connected in series and then connected in parallel with the fast switch (11). The capacitive module (3) comprises a fifth switch (31) and a capacitor (32), and the fifth switch (31) and the capacitor (32) are connected in series.

2. The system for reducing current and improving power quality according to claim 1, characterized in that: The system for reducing current and improving power quality has multiple operation modes, including a current limiting mode, a reactive power compensation mode, a series compensation mode and a harmonic filtering mode.

3. The system for reducing current and improving power quality according to claim 2, characterized in that: When the system for reducing current and improving power quality operates in a current limiting mode, the fast switch (11) and the third switch (6) are closed, and the first switch (4), the second switch (5), the fourth switch (7) and the fifth switch (31) are open.

4. The system for reducing current and improving power quality according to claim 2, characterized in that: When the system for reducing current and improving power quality operates in a reactive power compensation mode, the first switch (4), the third switch (6) and the fast switch (11) are closed, and the second switch (5) and the fourth switch (7) are open.

5. The system for reducing current and improving power quality according to claim 2, characterized in that: When the system for reducing current and improving power quality operates in a series compensation mode, the second switch (5) and the fast switch (11) are closed, and the first switch (4), the third switch (6) and the fourth switch (7) are opened.

6. The system for reducing current and improving power quality according to claim 2, characterized in that: When the system for reducing current and improving power quality operates in a harmonic filtering mode, the first switch (4) and the fourth switch (7) are closed, and the second switch (5) and the third switch (6) are open.

7. A method for reducing current, characterized in that: When the system for reducing current and improving power quality according to claim 1 operates in a current limiting mode, the system comprises the following steps: S101, closing the fast switch (11) and the third switch (6), and opening the first switch (4), the second switch (5), the fourth switch (7), and the fifth switch (31); S102, when the current collected by the first current transformer (2) exceeds the fault current setting value, the control protection system (8) calculates the number of reactors (12) that need to be put into use according to the setting value, and controls the corresponding number of fast switches (11) to be opened, while the other fast switches (11) remain closed, and the fault current is limited by connecting the reactor (12) in series to the line; S103, after a delay greater than the system backup protection set value time, the control protection system (8) sends a reclosing command to the fast switch (11) in the open state; after the reclosing command is completed, if the current detected by the second current transformer (13) is (0), the system action ends; if the second current transformer (13) still detects current, the control protection system (8) again sends a reclosing command to the fast switch (11) of the current limiting module (1) corresponding to the second current transformer (13); if the current detected by the second current transformer (13) is (0), the system action ends; if the second current transformer (13) still detects current, execute step S104; S104, closing the fourth switch (7) and generating an alarm of "abnormal closing of current-limiting fast switch".

8. The method for reducing current according to claim 7, characterized in that: When the system for reducing current and improving power quality as claimed in claim 1 operates in a reactive power compensation mode, the system comprises the following steps: S201, closing the first switch (4), the third switch (6) and the fast switch (11), and opening the second switch (5) and the fourth switch (7); S202, the control protection system (8) calculates the reactive power compensation demand of the system according to the power factor requirement and the collected remote measurement data of the first current transformer (2) and the voltage transformer (9); S203, the control protection system (8) calculates the number of capacitive modules (3) that need to be put into operation, closes the fifth switches (31) of the capacitive modules (3) that need to be put into operation, and the fifth switches (31) of the remaining capacitive modules (3) are in the open position.

9. The method for reducing current according to claim 8, characterized in that: When the system for reducing current and improving power quality as claimed in claim 1 operates in a series compensation mode, the system comprises the following steps: S301, closing the second switch (5) and the fast switch (11), and opening the first switch (4), the third switch (6), and the fourth switch (7); S302, the control and protection system (8) calculates the number of capacitive modules (3) that need to be put into operation according to the active transmission capacity requirement of the line and the collected telemetry data of the first current transformer (2) and the voltage transformer (9), closes the fifth switch (31) of the capacitive modules (3) that need to be put into operation, and the fifth switches (31) of the remaining capacitive modules (3) are in the open position.

10. The method for reducing current according to claim 1, characterized in that: When the system for reducing current and improving power quality according to claim 1 operates in a harmonic filtering mode, the system comprises the following steps: S401, closing the first switch (4) and the fourth switch (7), and opening the second switch (5) and the third switch (6); S402, the control protection system (8) collects the remote measurement of the voltage transformer (9), analyzes the harmonic components and the harmonic orders that need to be filtered out, calculates and obtains the series connection scheme of the inductor and capacitor, and closes the fast switch (11) of the current limiting module (1) and the fifth switch (31) of the capacitive module (3) that need to be put into operation.

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