Resistance-inductance type current limiter control method based on energy consumption branch multiplexing and resistance-inductance type current limiter

Abstract

The invention discloses a resistance-inductance type current limiter control method based on energy consumption branch multiplexing, and the method comprises the steps: enabling a resistance-inductance type current limiter to share one energy consumption branch on a plurality of DC lines at the outlet side of the same bus for a multi-terminal DC power grid; when the system operates normally, a thyristor in the resistance-inductance type current limiter is switched off, and direct current only flows through a current limiting branch of the current limiter; after the system breaks down and before the circuit breaker acts, a thyristor in the resistance-inductance type current limiter is kept in a turn-off state; when the circuit breaker acts to clear the fault current, a thyristor of the energy consumption branch is conducted, and fault energy of the circuit and the reactance of the current limiter is separated; after the DC fault is removed, the energy consumption branch thyristor is always conducted, the residual energy of the reactor of the fault current limiter is dissipated by the energy consumption branch, and the fault current limiter recovers to the initial state after the energy dissipation of the reactor is completed. The method is simple in topology and control logic and high in reliability, the number of energy consumption devices can be effectively reduced, and the economical efficiency of the current limiting equipment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current transmission, and in particular to a resistance-inductive current limiter control method based on energy-consuming branch multiplexing, and a resistance-inductive current limiter. Background Art

[0002] The use of flexible DC interconnection is an important development trend of my country's future power grid. Flexible DC technology based on modular multilevel converter (MMC) has the ability to control active and reactive power in four quadrants. It is an important technical means suitable for cross-regional large-capacity power transmission, large-scale consumption of new energy, and island power supply. However, the DC system has the characteristics of "low inertia and low impedance". Once a DC fault occurs, the fault current rises quickly and has a large peak value. During the fault process, the DC fault current does not naturally cross the zero point, making DC fault clearing the main constraint on the development of DC power grids. There are two main DC power grid fault clearing solutions: using a converter with fault clearing capability or using a DC circuit breaker. After a fault occurs, a converter with fault clearing capability can autonomously isolate the fault, but this solution is not selective, and the recovery time of the converter station is relatively long; the DC circuit breaker has the ability to selectively clear the fault line, but the current DC circuit breaker technology needs to be improved, and the investment cost is very high. Therefore, installing a fault current limiter to suppress the fault current and reduce the requirements for the circuit breaker's breaking capacity, thereby reducing costs, is a potential improvement solution.

[0003] The main current limiting elements of the current limiter are usually resistors, inductors, or a combination of resistors and inductors. The current limiting effect of the resistor-type current limiter is weak, but the fault clearing speed is fast. The inductor-type is the opposite, and the resistor-inductor type current limiter is a better choice for both current limiting capability and fault clearing speed. In order to further reduce the investment in the metal oxide varistor (MOV) of the circuit breaker and speed up the fault current clearing speed, the current limiter topology needs to add additional energy-consuming branches. Since a current limiter is required at both ends of each line, the overall energy-consuming device of the current limiting equipment will be large in size and high in cost. Summary of the invention

[0004] The purpose of the present invention is to provide a resistance-inductive current limiter control method based on energy-consuming branch multiplexing, and a resistance-inductive current limiter. The method and the resistance-inductive current limiter have simple topology and control logic, high reliability, and can effectively reduce the number of energy-consuming devices, thereby reducing the volume and weight of the current limiting equipment and improving the economy of the current limiting equipment.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A control method of a resistance-sensing current limiter based on energy-consuming branch multiplexing, the method comprising:

[0007] For multi-terminal DC power grids, on multiple DC lines on the same bus outlet side, the resistance-inductive current limiters share one energy-consuming branch;

[0008] When the system is operating normally, the thyristor in the resistance-inductive current limiter is turned off, and the DC current flows only through the current limiting branch of the current limiter;

[0009] After a fault occurs in the system and before the circuit breaker is activated, the thyristor in the resistance-inductive current limiter remains in the off state, and the current limiting branch reactor L located on the fault line 1 and L 2 Suppress the growth of fault current;

[0010] During the period when the circuit breaker operates to clear the fault current, the thyristor of the energy-consuming branch is turned on to separate the fault energy of the line and the current limiter reactance. The current limiter reactances of multiple lines consume energy through the same energy-consuming branch.

[0011] After the DC fault is removed, the energy-consuming branch thyristor T 1 The remaining energy of the reactor of the fault current limiter is dissipated by the energy consumption branch. After the reactor energy is completely dissipated, the fault current limiter returns to its initial state.

[0012] A resistance-inductive current limiter based on energy-consuming branch reuse, the resistance-inductive current limiter comprises a current-limiting branch and an energy-consuming branch, the current-limiting branch is arranged at both ends of each DC line; the energy-consuming branch is connected to the same bus outlet side line for sharing; the current-limiting branch and the energy-consuming branch are connected through two groups of diodes in the same direction, so that the current-limiting branch inductance and the energy-consuming branch can form a loop;

[0013] The current limiting branch includes an inductor L connected in series 1 and L 2 , used to provide a flow path for steady-state current when the system is operating normally, and to play an inductive current limiting role after a line fault occurs, thereby suppressing the growth of fault current;

[0014] The energy consumption branch includes a resistor R connected in series 1 , thyristor T 1 and resistor R 2 , thyristor T 1 The conduction direction is the resistance R 2 Pointing resistor R 1 It is used to limit the fault current in the early stage of the fault, and to separate the energy of the line and the inductance of the current limiting branch of the current limiter after the DC circuit breaker is operated, so that the fault energy in the inductance is dissipated by the energy consumption branch of the current limiter.

[0015] It can be seen from the technical solution provided by the present invention that the above method and the resistance-inductive current limiter have simple topology and control logic, high reliability, and can effectively reduce the number of energy-consuming devices, thereby reducing the volume and weight of the current limiting device and improving the economy of the current limiting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0017] Figure 1 A schematic flow chart of a method for controlling a resistance-inductive current limiter based on multiplexing of energy-consuming branches provided in an embodiment of the present invention;

[0018] Figure 2 A topological schematic diagram of a resistance-inductive current limiter in which multiple circuits share an energy-consuming branch according to an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of a DC current path in a resistance-inductive current limiter during normal operation of the system according to an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of a DC current path in a resistive-inductive current limiter before a circuit breaker is actuated after a fault occurs according to an embodiment of the present invention;

[0021] Figure 5 A schematic diagram of a DC current path in a resistive-inductive current limiter during the stage of circuit breaker actuation to clear fault current according to an embodiment of the present invention;

[0022] Figure 6 The figure is a schematic diagram of a DC current path in a resistive-inductive current limiter during the recovery phase after the fault current is cleared according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 1 The figure is a schematic flow chart of a method for controlling a resistance-inductive current limiter based on energy-consuming branch multiplexing provided by an embodiment of the present invention, the method comprising:

[0025] Step 1: For a multi-terminal DC power grid, on multiple DC lines on the same bus outlet side, the resistive-inductive current limiters share an energy-consuming branch;

[0026] In this step, if Figure 2 The figure shows a topological schematic diagram of a resistance-inductive current limiter in which multiple lines share an energy-consuming branch according to an embodiment of the present invention. The resistance-inductive current limiter includes a current limiting branch and an energy-consuming branch. The resistance-inductive current limiters on multiple lines on the same side of the converter station can share the same energy-consuming branch, thereby reducing repeated configuration of energy-consuming devices, which is beneficial to reducing the overall volume of the current limiting device and improving the economy of the current limiting device.

[0027] The current limiting branch is configured at both ends of each DC line; the energy consumption branch is connected to the same bus outlet side line for common use; the current limiting branch and the energy consumption branch are connected through two groups of diodes in the same direction, so that the current limiting branch inductance and the energy consumption branch can form a loop;

[0028] The current limiting branch includes an inductor L connected in series 1 and L 2 , used to provide a flow path for steady-state current when the system is operating normally, and to play an inductive current limiting role after a line fault occurs, thereby suppressing the growth of fault current;

[0029] The energy consumption branch includes a resistor R connected in series 1 , thyristor T 1 and resistor R 2 , thyristor T 1 The conduction direction is the resistance R 2 Pointing resistor R 1 ;

[0030] It is used to limit the fault current in the early stage of the fault. After the DC circuit breaker is operated, it is used to separate the energy of the line and the inductance of the current limiting branch of the current limiter, so that the fault energy in the inductance is dissipated by the energy consumption branch of the current limiter, avoiding energy consumption through the metal oxide arrester (MOV) of the DC circuit breaker, and reducing the total dissipated energy of the DC circuit breaker.

[0031] Step 2: When the system is operating normally, the thyristor in the resistance-inductive current limiter is turned off, and the DC current flows only from the current limiting branch of the current limiter;

[0032] In this step, if Figure 3 The figure shows a schematic diagram of the DC current path in the resistive-inductive current limiter during normal operation of the system according to an embodiment of the present invention. For a stable DC current, the inductance L of the current limiting branch is 1 and L 2 It exhibits very small impedance, so the current limiter produces very little power loss in steady state.

[0033] Step 3: After the system fails and before the circuit breaker is actuated, the thyristor in the resistance-inductive current limiter remains in the off state, and the current limiting branch reactor L located on the fault line 1 and L 2 Suppress the growth of fault current;

[0034] In this step, if Figure 4 FIG. 1 is a schematic diagram of a DC current path in a resistance-inductive current limiter before a circuit breaker is actuated after a fault occurs according to an embodiment of the present invention. If a fault occurs in line 1 among n lines, after the fault occurs and before the circuit breaker is actuated, the thyristor in the resistance-inductive current limiter remains in the off state, and the inductance L of the current limiting branch of the current limiter of line 1 is 1 and L 2 Ability to suppress the increase of fault current without delay;

[0035] At the same time, the current of other lines is fed into line 1, and the diode T connecting the current limiting branch and the energy consumption branch l1_1 , T li_1 ,

[0036] T li_2 (i=2,3…,n) is therefore turned on, and the feed current is controlled by the resistance R of the current limiting branch and the energy consumption branch of the non-fault line 2 inhibition.

[0037] Step 4: During the period when the circuit breaker operates to clear the fault current, the thyristor of the energy-consuming branch is turned on to separate the fault energy of the line and the current limiter reactance. The current limiter reactances of multiple lines consume energy through the same energy-consuming branch.

[0038] In this step, if Figure 5 FIG. 1 is a schematic diagram of a DC current path in a resistive-inductive current limiter during the stage of clearing the fault current when the circuit breaker is actuated according to an embodiment of the present invention. If a fault occurs in line 1 among n lines, during the period when the circuit breaker is actuated to clear the fault current, the thyristor T of the energy-consuming branch is turned on. 1 ;

[0039] Due to the access of the circuit breaker MOV, the DC fault current decreases and the inductance L of the current limiting branch 1 The freewheeling current circulates through the energy consumption branch, and the inductance L of the current limiting branch 2 The freewheeling current passes through the resistance R of the energy consumption branch 2 Circulating flow separates the fault energy in line 1 and the current limiter from each other. The circuit breaker only needs to dissipate the fault energy in line 1, which significantly reduces the energy consumption burden of the circuit breaker, thereby improving the device utilization and the economy of the current limiting equipment.

[0040] Step 5: After the DC fault is removed, the energy-consuming branch thyristor T 1The remaining energy of the reactor of the fault current limiter is dissipated by the energy consumption branch. After the reactor energy is completely dissipated, the fault current limiter returns to its initial state.

[0041] In this step, if Figure 6 FIG. 1 is a schematic diagram of a DC current path in a resistive-inductive current limiter in the recovery phase after the fault current is cleared according to an embodiment of the present invention. If a fault occurs in line 1 among n lines, after the DC fault is removed, the thyristor T of the energy-consuming branch 1 Always conducting, the remaining energy of the fault current limiter reactance is dissipated by the energy consumption branch;

[0042] Among them, the inductance L of the current limiting branch 1 The energy in the energy dissipation branch is determined by the resistance R 1 and R 2 Dissipation, inductance L of the current limiting branch 2 The energy in the energy dissipation branch is determined by the resistance R 2 dissipates, after which the fault current limiter returns to its initial state.

[0043] The embodiment of the present invention further provides a resistance-inductive current limiter based on energy consumption branch reuse, the resistance-inductive current limiter comprises a current limiting branch and an energy consumption branch, the current limiting branch is arranged at both ends of each DC line; the energy consumption branch is connected to the same bus outlet side line for sharing; the current limiting branch and the energy consumption branch are connected through two groups of diodes in the same direction, so that the current limiting branch inductance and the energy consumption branch can form a loop;

[0044] The current limiting branch includes an inductor L connected in series 1 and L 2 , used to provide a flow path for steady-state current when the system is operating normally, and to play an inductive current limiting role after a line fault occurs, thereby suppressing the growth of fault current;

[0045] The energy consumption branch includes a resistor R connected in series 1 , thyristor T 1 and resistor R 2 , thyristor T 1 The conduction direction is the resistance R 2 Pointing resistor R 1 It is used to limit the fault current in the early stage of the fault, and to separate the energy of the line and the inductance of the current limiting branch of the current limiter after the DC circuit breaker is operated, so that the fault energy in the inductance is dissipated by the energy consumption branch of the current limiter.

[0046] Based on the resistance-inductive current limiter, when the system is operating normally, the thyristor in the resistance-inductive current limiter is turned off, and the DC current flows only from the current limiting branch of the current limiter;

[0047] After a fault occurs in the system and before the circuit breaker is activated, the thyristor in the resistance-inductive current limiter remains in the off state, and the current limiting branch reactor L located on the fault line1 and L 2 Suppress the growth of fault current;

[0048] During the period when the circuit breaker operates to clear the fault current, the thyristor of the energy-consuming branch is turned on to separate the fault energy of the line and the current limiter reactance. The current limiter reactances of multiple lines consume energy through the same energy-consuming branch.

[0049] After the DC fault is removed, the energy-consuming branch thyristor T 1 The remaining energy of the reactor of the fault current limiter is dissipated by the energy consumption branch. After the reactor energy is completely dissipated, the fault current limiter returns to its initial state.

[0050] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to professional and technical personnel in the field.

[0051] In summary, the method and the resistive-inductive current limiter described in the embodiments of the present invention are simple to operate and have high reliability. They can reduce the number of configurations of current limiting devices on energy-consuming devices and semiconductor devices without increasing the control complexity, reduce the total volume of the current limiting device, and improve the overall economy of the current limiter. They are suitable for multi-terminal DC power grid scenarios.

[0052] In addition, a person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be implemented by instructing related hardware through a program, and the corresponding program can be stored in a computer-readable storage medium. The above-mentioned storage medium can be a read-only memory, a disk or an optical disk, etc.

[0053] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A control method of a resistance-sensing current limiter based on energy-consuming branch multiplexing, characterized in that: The method comprises: For multi-terminal DC power grids, on multiple DC lines on the same bus outlet side, the resistive-inductive current limiters share one energy-consuming branch; When the system is operating normally, the thyristor in the resistance-inductive current limiter is turned off, and the DC current flows only through the current limiting branch of the current limiter; After a system fault occurs and before the circuit breaker operates, the thyristor in the resistance-inductive current limiter remains in the off state, and the current limiting branch reactors L1 and L2 located on the fault line suppress the growth of the fault current; During the period when the circuit breaker operates to clear the fault current, the thyristor of the energy-consuming branch is turned on to separate the fault energy of the line and the current limiter reactance. The current limiter reactances of multiple lines consume energy through the same energy-consuming branch. After the DC fault is removed, the energy-consuming branch thyristor T1 is turned on, and the remaining energy of the reactor of the fault current limiter is dissipated by the energy-consuming branch. After the reactor energy is completely dissipated, the fault current limiter returns to its initial state.

2. The control method of the resistance-sensing current limiter based on energy-consuming branch multiplexing according to claim 1 is characterized in that: For the multi-terminal DC grid, on multiple DC lines on the same bus outlet side, the resistive-inductive current limiters share an energy-consuming branch, wherein: The resistance-inductive current limiter comprises a current limiting branch and an energy consumption branch, wherein the current limiting branch is arranged at both ends of each DC line; the energy consumption branch is connected to the same bus outlet side line for sharing; the current limiting branch and the energy consumption branch are connected through two groups of diodes in the same direction, so that the current limiting branch inductance and the energy consumption branch can form a loop; The current limiting branch includes inductors L1 and L2 connected in series, which are used to provide a flow path for steady-state current when the system is operating normally, and to play an inductor current limiting role after a line fault occurs to suppress the growth of fault current; The energy-consuming branch includes a resistor R1, a thyristor T1 and a resistor R2 connected in series, wherein the conduction direction of the thyristor T1 is from the resistor R2 to the resistor R1; the energy-consuming branch is used to limit the fault current at the initial stage of the fault, and is used to separate the energy of the line and the inductance of the current-limiting branch of the current limiter after the DC circuit breaker is actuated, so that the fault energy in the inductance is dissipated by the energy-consuming branch of the current limiter.

3. The control method of the resistance-sensing current limiter based on energy-consuming branch multiplexing according to claim 2 is characterized in that: After a fault occurs in the system and before the circuit breaker is actuated, the thyristor in the resistive-inductive current limiter remains in the off state, and the current limiting branch reactors L1 and L2 located on the fault line suppress the growth of the fault current, wherein: If a fault occurs in line 1 among the n lines, after the fault occurs and before the circuit breaker operates, the thyristor in the resistance-inductive current limiter remains in the off state, and the inductances L1 and L2 of the current limiting branch of the current limiter of line 1 suppress the increase of the fault current; At the same time, the current of other lines is fed into line 1, and the diode T connecting the current limiting branch and the energy consumption branch l1_1 , T li_1 , T li_2 (i=2,3…,n) is therefore turned on, and the feed-in current is suppressed by the resistor R2 of the current limiting branch and the energy consumption branch of the non-fault line.

4. The control method of the resistance-sensing current limiter based on energy-consuming branch multiplexing according to claim 2 is characterized in that: During the period when the circuit breaker operates to clear the fault current, the thyristor of the energy-consuming branch is turned on to separate the fault energy of the line and the current limiter reactance, and the current limiter reactances of multiple lines consume energy through the same energy-consuming branch, wherein: If a fault occurs in line 1 among the n lines, the thyristor T1 of the energy-consuming branch is turned on while the circuit breaker operates to clear the fault current.

5. The control method of the resistance-sensing current limiter based on energy-consuming branch multiplexing according to claim 2 is characterized in that: After the DC fault is removed, the energy-consuming branch thyristor T1 is turned on, and the remaining energy of the reactor of the fault current limiter is dissipated by the energy-consuming branch. After the reactor energy is completely dissipated, the fault current limiter returns to the initial state, wherein: If a fault occurs in line 1 among the n lines, after the DC fault is removed, the thyristor T1 of the energy-consuming branch is always turned on, and the remaining energy of the fault current limiter reactance is dissipated by the energy-consuming branch; The energy in the inductor L1 of the current limiting branch is dissipated by the resistors R1 and R2 of the energy consuming branch, and the energy in the inductor L2 of the current limiting branch is dissipated by the resistor R2 of the energy consuming branch, after which the fault current limiter returns to the initial state.

6. A resistance-sensing current limiter based on energy-consuming branch multiplexing, characterized in that: The resistance-inductive current limiter comprises a current limiting branch and an energy consumption branch, wherein the current limiting branch is arranged at both ends of each DC line; the energy consumption branch is connected to the same bus outlet side line for sharing; the current limiting branch and the energy consumption branch are connected through two groups of diodes in the same direction, so that the current limiting branch inductance and the energy consumption branch can form a loop; The current limiting branch includes inductors L1 and L2 connected in series, which are used to provide a flow path for steady-state current when the system is operating normally, and to play an inductor current limiting role after a line fault occurs to suppress the growth of fault current; The energy-consuming branch includes a resistor R1, a thyristor T1 and a resistor R2 connected in series, wherein the conduction direction of the thyristor T1 is from the resistor R2 to the resistor R1; the energy-consuming branch is used to limit the fault current at the initial stage of the fault, and is used to separate the energy of the line and the inductance of the current-limiting branch of the current limiter after the DC circuit breaker is actuated, so that the fault energy in the inductance is dissipated by the energy-consuming branch of the current limiter.

7. The resistance-sensing current limiter based on energy-consuming branch multiplexing according to claim 6, characterized in that: When the system is operating normally, the thyristor in the resistance-inductive current limiter is turned off, and the DC current flows only through the current limiting branch of the current limiter; After a system fault occurs and before the circuit breaker operates, the thyristor in the resistance-inductive current limiter remains in the off state, and the current limiting branch reactors L1 and L2 located on the fault line suppress the growth of the fault current; During the period when the circuit breaker operates to clear the fault current, the thyristor of the energy-consuming branch is turned on to separate the fault energy of the line and the current limiter reactance. The current limiter reactances of multiple lines consume energy through the same energy-consuming branch. After the DC fault is removed, the energy-consuming branch thyristor T1 is turned on, and the remaining energy of the reactor of the fault current limiter is dissipated by the energy-consuming branch. After the reactor energy is completely dissipated, the fault current limiter returns to its initial state.

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