CN106300308A - A kind of transition magnetic field impulse induction type current carry circuit and using method thereof - Google Patents

Abstract

The disclosure discloses a transient magnetic pulse induction current transfer circuit and a method for using the same. The transfer circuit includes a main current circuit and a transfer current circuit. The current transfer circuit includes a transformer, and the current transfer circuit can be used to complete fast current transfer and realize current limitation or breaking. At the same time, the isolation of the capacitor in the second circuit from the DC system can significantly reduce the voltage level and volume of the charging unit and improve the reliability of the transfer. The usage method can further realize various engineering application functions, such as DC circuit breaker, AC fast circuit breaker, AC and DC current limiter.

Description

A transient magnetic pulse induction current transfer circuit and its application method

technical field

The disclosure belongs to the field of electronic circuits, and in particular relates to a transient magnetic pulse induction current transfer circuit and a use method thereof.

Background technique

With the continuous improvement of the capacity of the DC power system, the DC power transmission and transformation technology is booming, and at the same time, higher requirements are placed on the stability and safety of the system. Among the various faults that may occur in the power system, short-circuit faults are the most harmful to the power grid and have a high probability of occurrence. Since the peak value of the short-circuit current of the DC system will rise to a very high level in a short period of time, the removal and protection of the short-circuit fault is an important issue for the development of the DC system. The difficulty of DC breaking is mainly reflected in two aspects: one is that DC current does not have a natural zero-crossing point like AC current, so it is very difficult for the current to cross zero, and it is necessary to artificially create the current zero-crossing point; Absorb huge amounts of energy.

Contents of the invention

Based on this, the present disclosure discloses a transient magnetic pulse induction current transfer circuit, the circuit includes a main current circuit, a transfer current circuit and an access port;

The main current circuit is used to continuously carry current or conduct current temporarily;

The transfer current circuit is used to bear the current transferred from the main current circuit;

The access port is used for connecting with external systems.

The present disclosure also discloses a method for using a transient magnetic pulse current, and the method includes the following steps:

S1. According to the current amplitude and change rate of the main current circuit or according to the external transfer instruction received, it is judged that a short circuit fault occurs, and an opening signal is sent to the mechanical switch in the main current circuit;

S2. Turn on any two thyristors among the thyristors B1 to B4 according to the direction of current flow, and form a discharge circuit with the third circuit A3 and the inductor; at the same time, a rising voltage is generated at both ends of the secondary inductor until the arrester is turned on, and the main The current in the current circuit is gradually diverted to the first circuit;

S3. After the current in the main circuit current is completely transferred, a voltage is established at both ends of the arrester, which can complete the current limiting or breaking function.

The beneficial effects of the present disclosure: 1) The voltage generated by the transformer can directly transfer the current to the arrester, which saves the process of transferring the current to capacitors or power electronic devices, and the reliability of current limiting or breaking speed is much higher than that of traditional technologies ;

2) The present disclosure can realize the isolation of the capacitor charging unit and the DC system, significantly reduce the voltage level and volume of the charging unit, and improve the operation reliability;

3) A power semiconductor device or a trigger gap is used to form a bridge circuit on the primary side of the transformer of the transfer current circuit, which can realize bidirectional current transfer, and the withstand voltage and cost of the bridge circuit are low.

Description of drawings

1 is a schematic structural diagram of a transient magnetic pulse induction current transfer circuit according to an embodiment of the present disclosure;

2 is a schematic structural diagram of a transient magnetic pulse induction current transfer circuit in one-way operation according to an embodiment of the present disclosure;

3 is a schematic structural diagram of another unidirectional operation of the transient magnetic pulse induction current transfer circuit according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a current sign of a transient magnetic pulse induction current transfer circuit according to an embodiment of the present disclosure;

5(a) is a schematic diagram of the current flow of the main current circuit when the magnetic coupling commutation transfer circuit transfers current according to an embodiment of the present disclosure;

5(b) is a schematic diagram of the current flow of the main current circuit and the transfer current circuit when the magnetic coupling commutation transfer circuit transfers current according to an embodiment of the present disclosure;

5(c) is a schematic diagram of the current flow of the transfer current circuit when the magnetic coupling commutation transfer circuit transfers current according to an embodiment of the present disclosure;

FIG. 6 is a graph showing current changes in each circuit when the transient magnetic pulse induction current transfer circuit corresponds to the transfer current in FIG. 5 according to an embodiment of the present disclosure;

7 is a circuit diagram of a transient magnetic pulse inductive current transfer circuit according to an embodiment of the present disclosure;

8 is a circuit diagram of a transient magnetic pulse inductive current transfer according to another embodiment of the present disclosure;

FIG. 9 is a schematic diagram of the steps of the switching method of the hybrid circuit breaker with two-way switching optimized in FIG. 8 according to an embodiment of the present disclosure.

detailed description

The following detailed description is merely exemplary in nature and not intended to limit application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. Unless expressly stated to the contrary, the word "comprise" and its various variations should be understood as implying the inclusion of stated elements but not excluding any other elements.

In one embodiment, the present disclosure discloses a transient magnetic pulse inductive current transfer circuit, the circuit comprising a main current circuit, a transfer current circuit and an access port;

The main current circuit is used to continuously carry current or conduct current temporarily;

The transfer current circuit is used to bear the current transferred from the main current circuit;

The access port is used for connecting with external systems.

The purpose of this embodiment is to provide a transient magnetic pulse induction current transfer circuit, which uses a transformer and an arrester in series to realize rapid transfer and breaking of current, eliminating the need to use capacitors or power electronic devices to establish voltage to transfer the system current to The arrester process. By controlling the primary capacitor discharge of the transformer isolated from the DC system, it generates a pulse current, and at the same time, the secondary side of the transformer connected to the DC system induces a high voltage to make the arrester conduct and form a pulse current, which is used to resist the main current. The current circuit transfers the current from the main current circuit to the transfer circuit including the arrester and transformer, and then uses the arrester to complete the breaking or limiting of the current.

In one embodiment, the main current circuit is composed of one or more of mechanical switches, power electronic devices and current limiters connected in series or in parallel.

In this embodiment, the main current circuit can continuously carry or conduct current temporarily. The main current circuit includes one or more series-parallel combinations of mechanical switches, power electronic devices, current limiters, and wires. The main current circuit serves as The two ends of the transferred part in the transfer circuit of this patent are used as the access ports of this patent to the external system.

In one embodiment, the transfer current circuit comprises a first circuit and a second circuit;

The first circuit includes a secondary inductor and a lightning arrester, and the secondary inductor is connected in series with the lightning arrester;

The second circuit includes a precharge capacitor, an inductor, thyristors B1-B4 and a primary inductor;

The precharge capacitor and inductor are connected in series to form a third circuit A3;

The thyristors B1 to B4 include power semiconductors or trigger gaps;

The thyristors B1 to B4 are connected in series to form a loop and then connected in series with the primary inductor;

The thyristors B1 to B4 and the third circuit A3 form a bridge circuit;

The primary side inductor and the secondary side inductor form a transformer.

In this embodiment, the transfer current circuit has the ability to withstand the transfer current from the main current circuit, and includes a secondary inductor and a lightning arrester. The first circuit composed of secondary inductors and lightning arresters in series; the second circuit composed of the third circuit A3 composed of pre-charged capacitors or superconducting inductors, B1-B4 composed of power semiconductor devices or trigger gaps, and the primary inductor L0 in series circuit, the primary inductor and the secondary inductor form a transformer, the first circuit is connected in parallel with the main current circuit, and the second circuit may or may not be insulated from the first circuit.

According to the different current directions, in order to realize the transfer of bidirectional current, power semiconductor devices or trigger gaps are used on the primary side of the transfer current circuit transformer to form a bridge circuit.

Before the current transfer, the current flows through the mechanical switch A1 in the main current circuit; at this time, the power electronic devices, trigger switching devices and thyristors B1 to B4 in the transfer current circuit are in the off state, and the transfer current circuit No current flows through the first circuit and the second circuit.

In one embodiment, the first circuit is connected in parallel with the main current circuit, and the second circuit is selectively insulated or not insulated from the first circuit.

Further, the primary-side inductor and the secondary-side inductor are air-core inductors or inductors with magnetic cores, which are composed of one or more inductors connected in series or in parallel.

Further, the arrester is composed of one or more series-parallel connections of zinc oxide arresters, tubular arresters or valve arresters.

Further, the mechanical switch includes one of an ordinary mechanical switch based on a spring mechanism, a high-speed mechanical switch based on electromagnetic repulsion, a mechanical switch driven by a high-speed motor, or a high-speed mechanical switch driven by an explosion;

The current limiter includes one of a superconducting fault current limiter SFCL, a liquid metal current limiter LMFCL, and a PTC current limiter.

Further, the power semiconductor device includes one or more series-parallel combinations of power diodes, thyristors, IGBTs, and IGCTs.

In one embodiment, under normal working conditions, the current in the circuit flows through the main current circuit. At this time, the lightning arresters and thyristors B1 to B4 in the transfer current circuit are in the off state, and the first circuit and the second circuit There is no current flowing in the two circuits;

When the transient magnetic pulse inductive current transfer circuit needs to act, by measuring the current amplitude and rate of change of the main current circuit to determine the power semiconductor device or trigger gap in the transfer current circuit and the mechanism in the main current circuit Whether the switch and power semiconductor devices operate and the corresponding action timing.

In one embodiment, the present disclosure discloses a method for using a transient magnetic pulse current, the method for using includes the following steps:

S1. According to the current amplitude and change rate of the main current circuit or according to the external transfer instruction received, it is judged that a short circuit fault occurs, and an opening signal is sent to the mechanical switch in the main current circuit;

S2. Turn on any two thyristors among the thyristors B1 to B4 according to the direction of current flow, and form a discharge circuit with the third circuit A3 and the inductor; at the same time, a rising voltage is generated at both ends of the secondary inductor until the arrester is turned on, and the main The current in the current circuit is gradually diverted to the first circuit;

S3. After the current in the main circuit current is completely transferred, a voltage is established at both ends of the arrester, which can complete the current limiting or breaking function.

The method described in this embodiment can realize various engineering application functions, such as DC circuit breaker, AC fast circuit breaker, AC and DC current limiter. On the one hand, the present disclosure can directly transfer the main circuit current to the lightning arrester, directly establish the breaking voltage to complete current breaking and limiting, and save the intermediate process of transferring the main circuit current to capacitors or power electronic devices. At the same time, the capacitor charging unit on the primary side of the transformer is isolated from the DC system, which significantly reduces the voltage level and volume of the charging unit and improves the reliability of breaking. In addition, a bridge circuit is formed by using power semiconductor devices or trigger gaps on the primary side of the current transfer circuit transformer, which can realize bidirectional current transfer, and the bridge circuit has low withstand voltage and low cost. The current using method of the present disclosure has simple circuit, few parts and short reaction time, which improves the sensitivity and reliability of practical application.

In one embodiment, the present disclosure discloses a transient magnetic pulse induction current transfer circuit and its use method, as shown in FIG. 1 , a schematic structural diagram of a transient magnetic pulse induction current transfer circuit according to an embodiment of the present disclosure. , which includes a main current circuit and a transfer current circuit. In order to better illustrate the working process of the transfer circuit, this paper provides a schematic diagram of a direct current flowing in and out of the disclosure in a certain direction, as shown in FIG. 2 . The current direction of the power semiconductor device that may exist in FIG. 2 is consistent with the arrow direction of the mechanical switch A1, thyristors B2 and B3 in the figure. FIG. 3 shows a schematic diagram of direct current flowing in and out of the present disclosure in another direction.

Referring to the transient magnetic pulse induction current transfer circuit disclosed in Figures 1, 2 and 3, the transient magnetic pulse induction current transfer circuit includes a main current circuit, a transfer current circuit and an end connected to an external system, the main current The circuit is connected in parallel with the transfer current circuit.

The main current circuit may be one or more series-parallel combinations of mechanical switches, power electronic devices and current limiters.

The transfer current circuit includes a first circuit composed of a secondary inductor L1 and an arrester connected in series. A third circuit A3 composed of a pre-charged capacitor or a superconducting inductor, a second circuit composed of a power semiconductor device or a trigger gap B1-B4 and a primary inductor L0 connected in series, the primary inductor and the secondary inductor A transformer is formed, the first circuit is connected in parallel with the main current circuit, and the second circuit can be insulated from the first circuit.

According to different current directions, in order to realize bidirectional current transfer, power semiconductor devices or trigger gaps are used on the primary side of the transfer current circuit transformer to form a bridge circuit.

Under normal working conditions, current flows through the mechanical switch A1 in the main current circuit; at this time, the power electronic devices, trigger switching devices and thyristors B1 to B4 in the transfer current circuit are in an off state, and the transfer current circuit No current flows through the first circuit and the second circuit.

When the transient magnetic pulse induction current transfer circuit is applied to a DC circuit breaker and needs to transfer current, the power semiconductor device in the transfer current circuit is determined by measuring the current amplitude and rate of change of the main current circuit Whether the trigger gap and the mechanical switch in the main current circuit, the power semiconductor device and the corresponding action sequence.

Wherein, the mechanical switch can be an ordinary mechanical switch based on a spring mechanism, a high-speed mechanical switch based on electromagnetic repulsion, a mechanical switch driven by a high-speed motor or a high-speed mechanical switch driven by an explosion; the current limiter includes but is not limited to a super fault current limiter SFCL, liquid metal current limiter LMFCL, PTC current limiter; the power semiconductor device includes but not limited to one or any combination of series or parallel connection of power diode, thyristor, IGBT, IGCT.

Wherein, the primary side inductor and the secondary side inductor constituting the transformer are air-core inductors or inductors with magnetic cores, and the primary side and the secondary side can be connected in series or in parallel by one or more inductors. The second circuit for transferring current is composed of power electronic devices or trigger gaps B1-B4 to form a bridge circuit.

Figure 4 shows the current signs of each branch of the transfer current circuit, where i0 is the current flowing through the third circuit A3 and the primary inductor L0 in the second transfer current circuit, i1 is the current flowing through the main current circuit, and i2 is Diverts the current in the first circuit with the secondary inductor L1.

In the main current circuit, taking the current flowing from left to right as an example, Figure 5(a) to (c) shows the current direction of each branch when the current is transferred, specifically for each branch corresponding to each moment from t1 to t5 The direction of the circuit current. Figure 6 shows the current variation curves of each branch.

In one embodiment, referring to FIG. 9 , using the transient magnetic pulse induced current using method includes the following steps.

In the first step S1, an opening signal is sent to the main current loop mechanical switch A1. Due to the delay of the mechanical switch action, the fracture has not yet been formed at this time.

In the second step S2, according to the current flow direction, the controller sends a turn-on signal to two of the bridge thyristors B2 to B4 in the second circuit of the transfer circuit. The third circuit A3 and the primary inductor L0 form a discharge loop. At the same time, due to the induction effect, a rapidly rising voltage is generated at both ends of the secondary inductor L1 of the first circuit until the lightning arrester is turned on. The current of the main current loop is gradually transferred to the first circuit of the transfer current. After a period of time, the entire current is diverted to the diverting current first circuit. A fracture is then formed between the mechanical switch contacts.

In the third step S3, after the current transfer is completed, a certain voltage is established at both ends of the arrester, which can complete the current limiting or breaking function.

In one embodiment, referring to Fig. 9, the specific operation steps of the DC circuit breaker composed of the transient magnetic pulse induction current transfer circuit include the following aspects, and the current takes the main current circuit as an example:

The system is running normally, the mechanical switch is closed, the thyristor is disconnected, and all the current flows through the mechanical switch in the main current circuit, as shown in Figure 5(a), where the rated current of the system is I.

At time t1, a short-circuit fault occurs in the system, and the current of the main current circuit begins to rise. Between t0 and t1, when the short-circuit threshold of the system is exceeded, the controller sends an opening signal to the mechanical switch A1 of the main current circuit. Due to the delay of the mechanical switch action, the fracture has not yet been formed at this time.

At time t2, the thyristors B2 and B3 are turned on, and the precharged capacitor A3 forms a discharge circuit with the primary inductor L0. At the same time, due to induction, a rapidly rising voltage is generated at both ends of the inductance L1 of the first circuit until the lightning arrester is turned on. As shown in Figure 5(b), the main current loop current is gradually transferred to the first circuit of the transfer current.

At time t3, the main circuit current is all transferred to the first circuit in the transfer current circuit, as shown in FIG. 5(c). A fracture is then formed at both ends of the mechanical switch contact.

At time t4, because the conduction voltage of the arrester is higher than the high voltage of the system, the current of the transfer current circuit rapidly drops to zero, and the breaking ends.

At time t5, the current in the second circuit of the transfer current circuit is zero.

The transfer current circuit described in the present disclosure does not require only one transformer, but may be a series or parallel combination of multiple transformers and their primary side circuits, as shown in FIG. 7 and FIG. 8 .

The transfer circuit disclosed in this embodiment includes a main current circuit and a transfer current circuit. The transfer current circuit includes a transformer, and the transfer current circuit can be used to complete fast current transfer and realize current limitation or breaking. At the same time, the isolation of the capacitor in the second circuit from the DC system can significantly reduce the voltage level and volume of the charging unit and improve the reliability of the transfer.

Although the embodiments of the present disclosure have been described above in conjunction with the accompanying drawings, the present disclosure is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are only illustrative, instructive, and not restrictive . Those skilled in the art can make many forms under the enlightenment of this description and without departing from the protection scope of the claims of the present disclosure, and these all belong to the protection of the present disclosure.

Claims (10)

1. A transient magnetic pulse induction current transfer circuit, characterized in that: the circuit includes a main current circuit, a transfer current circuit and an access port; The main current circuit is used to continuously carry current or conduct current temporarily; The transfer current circuit is used to bear the current transferred from the main current circuit; The access port is used for connecting with the outside. 2. The circuit according to claim 1, wherein preferably, the main current circuit is composed of one or more of mechanical switches, power electronic devices and current limiters connected in series or in parallel. 3. The circuit according to claim 2, wherein the transfer current circuit comprises a first circuit and a second circuit; The first circuit includes a secondary inductor and a lightning arrester, and the secondary inductor is connected in series with the lightning arrester; The second circuit includes a precharge capacitor, an inductor, thyristors B1 to B4 and a primary inductor; The precharge capacitor and inductor are connected in series to form a third circuit A3; The thyristors B1 to B4 include power semiconductors or trigger gaps; The thyristors B1 to B4 are connected in series to form a loop and then connected in series with the primary inductor; The thyristors B1 to B4 and the third circuit A3 form a bridge circuit; The primary side inductor and the secondary side inductor form a transformer. 4. The circuit according to claim 3, characterized in that: the first circuit is connected in parallel with the main current circuit, and the second circuit is selectively insulated or not insulated from the first circuit. 5 . The circuit according to claim 3 , wherein the primary side inductor and the secondary side inductor are air-core inductors or inductors with magnetic cores, which are composed of one or more inductors connected in series or in parallel. 6. The circuit according to claim 3, wherein the arrester is one or more series-parallel connections of zinc oxide arresters, tubular arresters or valve arresters. 7. The circuit according to claim 2, characterized in that: said mechanical switch comprises a common mechanical switch based on a spring mechanism, a high-speed mechanical switch based on electromagnetic repulsion, a mechanical switch driven by a high-speed motor or a high-speed mechanical switch driven by an explosion one of the switches; The current limiter includes one of a superconducting fault current limiter SFCL, a liquid metal current limiter LMFCL, and a PTC current limiter. 8. The circuit according to claim 3, wherein the power semiconductor device comprises one or more series-parallel combinations of power diodes, thyristors, IGBTs, and IGCTs. 9. Any circuit according to claim 1-8, characterized in that: under normal working conditions, the current in the transient magnetic pulse induction current transfer circuit flows through the main current circuit, at this time, the Lightning arresters and thyristors B1 to B4 in the transfer current circuit are in an off state, and no current flows through the first circuit and the second circuit; When the transient magnetic pulse inductive current transfer circuit needs to act, by measuring the current amplitude and rate of change of the main current circuit, determine the power semiconductor device or the trigger gap in the transfer current circuit and the current in the main current circuit Whether mechanical switches and power semiconductor devices operate and the corresponding action timing. 10. A method for using a transient magnetic pulse type current, characterized in that the method for using comprises the following steps: S1. According to the current amplitude and change rate of the main current circuit or according to the external transfer instruction received, when it is judged that a short circuit fault occurs, an opening signal is sent to the mechanical switch in the main current circuit; S2. Turn on the two thyristors in the thyristors B1 to B4 according to the current flow direction of the circuit, and form a discharge circuit with the third circuit A3 and the inductor. At the same time, a rising voltage is generated at both ends of the secondary inductor until the arrester is turned on. , the current in the main current circuit gradually shifts to the first circuit; S3. After the current in the main circuit current is completely transferred, a voltage is established at both ends of the arrester, which can complete the current limiting or breaking function.