CN111640602A - Multi-fracture direct-current switch equipment with controllable transfer branch oscillation current and control method - Google Patents

Abstract

The invention relates to a multi-break DC switch device and a control method with a controllable oscillating current of a transfer branch. Its main flow branch includes a plurality of mechanical switches, which are connected in series in the transmission and distribution circuit of the power system; the controllable branch is composed of one or more controllable switch modules, which are respectively connected in parallel with one or more mechanical switches; the transfer branch is composed of one or more controllable switch modules. The circuit includes energy storage module and energy storage auxiliary module. All mechanical switches with controllable switch modules in the transfer branch and the main flow branch form a parallel relationship; The switches are in a parallel relationship. The DC switchgear has sufficient on-off capacity and can act quickly with load, and can be used as a circuit breaker or load switch in unipolar, bipolar and homopolar high-voltage DC transmission lines or medium and low-voltage DC distribution lines. , play the role of control, protection and isolation of faults, with the advantages of small size, good economy, high versatility and fast breaking speed.

Description

Multi-break DC switchgear with controllable oscillating current of transfer branch and control method

technical field

The invention relates to the technical field of switchgear, in particular to a multi-break DC switchgear and a control method with a controllable oscillating current of a transfer branch.

Background technique

At present, due to changes in the structure of power production, transmission, and consumption, flexible DC systems have become an important development direction of power systems, and DC circuit breakers play a key role in the transmission and distribution fields of flexible DC systems.

There are many topology schemes for DC circuit breakers, but the reliability needs to be further verified. The current DC circuit breaker topology with capacitors for current transfer has the problem of uncontrollable oscillating current. If controllable electronic components are used to control the oscillating current bidirectionally, it will lead to higher power transmission costs.

SUMMARY OF THE INVENTION

Aiming at the problem that the oscillating current of the current DC circuit breaker topology structure using capacitors for current transfer cannot be controlled, the present invention provides a multi-break DC switch device and a control method with controllable oscillating current in the transfer branch, which can be applied to high voltage, medium voltage and In the low-voltage field, it has the advantages of good economy, high versatility and fast breaking of oscillating current.

In order to achieve the above object, the present invention provides a multi-break DC switch device with controllable oscillating current of the transfer branch, which is characterized in that it includes a main control branch, a controllable switch module, a transfer branch, and an energy consumption branch. , the first side switch and the second side switch;

The main control branch includes the first to nth mechanical switches, which are sequentially connected in series in the power transmission and distribution circuit of the power system; n≥1;

The controllable switch module includes first to m controllable switch modules, each controllable switch module can form a parallel relationship with any single or adjacent multiple mechanical switches, and there are a total of k mechanical switches with it. Constitute a parallel relationship; 0<m≤k≤n;

The transfer branch is connected in parallel with the series structure of the first to a-th mechanical switches; k≤a≤n;;

Under the control of the first side switch and the second side switch, the two ends of the energy dissipation branch are respectively connected to the two ends of the series structure of the first to nth mechanical switches.

Further, the transfer branch includes an energy storage module and an energy storage auxiliary module connected in series; the energy storage module is a capacitor or includes: a resistor, a discharge control switch and a capacitive element, and the resistor is connected in series with the discharge control switch and then connected in parallel with the capacitive element ; The energy storage auxiliary module is a current limiting element.

Further, the energy-consuming branch is a lightning arrester.

Further, the transfer branch is controlled by the first side switch to be connected in parallel to the series structure of the first to a-th mechanical switches.

Further, the controllable switch module includes a bidirectional controllable switch and a lightning arrester connected in parallel with it; the bidirectional controllable switch is a bridge structure or an inverse series structure composed of diodes, IGBTs, IECTs or GTOs.

Further, the first side switch and the second side switch are mechanical switches with insulation and isolation capabilities.

Further, the first to m-th mechanical switches are isolating switches or vacuum switches.

Another aspect of the present invention provides a control method for the multi-break DC switchgear with controllable oscillating current of the transfer branch, comprising:

1) The closing operation process:

The initial state is that the first to kth mechanical switches are closed, and all other switches are disconnected;

If the system needs a closing operation, first control the transfer branch to release energy from the internal energy storage element, and then disconnect the energy release circuit after the energy is released;

Close the first side switch and the second side switch;

At the same time, the remaining n-k mechanical switches are closed to complete the closing operation;

2) Opening operation process:

The controller issues an order to make the control terminals of the m controllable switch modules provide a conduction signal to make it in a "pre-conduction" state, and then issues an order to make the 1st to nth mechanical switches perform the opening operation; when any one When the arc voltage of the mechanical switch is greater than the threshold voltage of the parallel controllable switch module, the parallel controllable switch module is in the "on" state, and the current through the mechanical switch is transferred to the parallel controllable switch module; if When the terminal voltage of the controllable switch module exceeds the triggering threshold of the arrester, the arrester in the controllable switch module will be triggered to absorb energy;

After the preset time, the mechanical switch has extinguished the arc, the controllable switch module is turned off, the current is transferred to the transfer branch, and the energy storage element inside the transfer branch is charged; charging makes the voltage of the energy storage element It rises rapidly, triggering the action of the energy-consuming branch and absorbing the remaining energy; when the 1st to nth mechanical switches all recover the insulating ability, the oscillating current generated by the transfer branch is cut off;

After the DC switch device has passed the preset time, the oscillating current generated by the transfer branch has been cut off, and the controller sends an instruction to disconnect the first side switch (6) and the second side switch (7), and then sends an instruction to make the first side switch (6) and the second side switch (7). Until the kth mechanical switch is closed.

Further, after the DC switchgear is disconnected, the controller sends an instruction to make the device transfer the multi-break DC switchgear whose branch oscillating current is controllable to perform the closing operation process, and determine if the DC switchgear does not receive the system again after closing. If the fault signal of the system is received again, the closing is completed; if the DC switchgear receives the fault signal of the system again after closing, the opening operation process is performed.

The above-mentioned technical scheme of the present invention has the following beneficial technical effects:

(1) The DC switchgear of the present invention has sufficient on-off capacity and can act quickly with load, and can be used as a circuit breaker or load switch in unipolar, bipolar and homopolar high-voltage DC transmission lines or medium and low voltage In the DC distribution line, it plays the role of control, protection and isolation of faults, and has the advantages of small size, good economy, high versatility and fast breaking speed.

(2) The first m mechanical switches of the present invention are connected in parallel with controllable switch modules, and other mechanical switches are not connected in parallel, which can reduce the cost and the complexity of control.

(3) Advantages of setting up the first and second side switches in the present invention Setting the first and second side switches can form obvious breakpoints and establish reliable insulation gaps during equipment maintenance.

(4) The transfer branch of the present invention is connected in parallel with the series structures of the first to a mechanical switches, which can ensure the reliability of the switchgear during opening and closing.

Description of drawings

Figure 1 is a schematic structural diagram of a multi-break DC switchgear with controllable oscillating current in a transfer branch;

Fig. 2 is the embodiment of the three-break series DC switchgear with controllable oscillating current of the transfer branch of the present invention;

Fig. 3 is a three-fracture series structure embodiment in which the controllable branches of the present invention are bridge-connected by electronic components;

FIG. 4 is an embodiment of the three-break series structure in which the transfer branch is directly connected in parallel at both ends of the mechanical switch according to the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present invention.

The present invention provides a multi-break DC switch device with controllable oscillating current of a transfer branch. With reference to FIG. 1 , it includes a main control branch, a controllable switch module, a transfer branch, an energy consumption branch, and a first side switch 6 and second side switch 7.

The main control branch includes the first to nth mechanical switches 1-1 to 1-n, which are sequentially connected in series in the power transmission and distribution circuit of the power system; n≥1.

The first to m controllable switch modules are included, and each controllable switch module can form a parallel relationship with any single or adjacent multiple mechanical switches, and a total of k mechanical switches form a parallel relationship with it; 0 <m≤k≤n.

The transfer branch is connected in parallel with the first to a-th mechanical switches in series structure; k≤a≤n.

Under the control of the first side switch 6 and the second side switch 7, both ends of the energy dissipation branch are connected to both ends of the series structure of the first to nth mechanical switches.

Further, the transfer branch can be connected to point A, and the series structure connected in parallel to the first to a-th mechanical switches is controlled by the first side switch 6; the first side switch 6 can play an isolation function. The transfer branch may be connected to point B in parallel to the series structure of the first to ath mechanical switches. The first side switch 6 and the second side switch 7 are mechanical switches with insulation and isolation capabilities.

Further, the transfer branch includes an energy storage module 3 and an energy storage auxiliary module 4 connected in series; the energy storage module 3 includes: a resistor, a discharge control switch and a capacitive element, and the resistor is connected in series with the discharge control switch and then connected in parallel with the capacitive element ; If the resistor is connected in parallel, the resistor can absorb the energy of the capacitive element after the circuit breaker is broken, and it has the conditions to meet the reclosing function in a short time. The mechanical switch is connected in series in the main current branch. During the opening operation, when the mechanical switch restores the insulation capability, the transfer branch can cut off the oscillating current generated by the capacitive and inductive components in the transfer branch.

Further, the energy storage auxiliary module 4 is a current limiting element, which can be a resistor, an inductor or other elements, and the energy storage auxiliary module 4 can play a current limiting role.

Further, the energy dissipation branch is the arrester 5, which absorbs the energy in the circuit after being turned on.

Further, the controllable switch module includes a bidirectional controllable switch and a lightning arrester connected in parallel with it. The bidirectional controllable switch can be a controllable electronic component, a series or parallel combination of a controllable electronic component and a power diode, and the controllable electronic component can be a single, multiple or mixed electronic components (such as IGBT/IECT). , GTO, etc.), with unidirectional or bidirectional current-carrying and shutdown capabilities.

Further, the first to m-th mechanical switches are isolating switches or vacuum switches.

Another aspect of the present invention provides a control method for the multi-break DC switchgear with controllable oscillating current of the transfer branch, comprising:

1) The closing operation process:

The initial state is that the first to mth mechanical switches are closed, and all other switches are disconnected;

If the system needs a closing operation, first control the transfer branch to release energy from the internal energy storage element, and then disconnect the energy release circuit after the energy is released;

Close the first side switch 6 and the second side switch 7;

At the same time, the remaining n-k mechanical switches are closed to complete the closing operation;

2) Opening operation process:

The controller issues an order to make the control terminals of the m controllable switch modules provide a conduction signal to make it in a "pre-conduction" state, and then issues an order to make the 1st to nth mechanical switches perform the opening operation; when any one When the arc voltage of the mechanical switch is greater than the threshold voltage of the parallel controllable switch module, the parallel controllable switch module is in the "on" state, and the current through the mechanical switch is transferred to the parallel controllable switch module; if If the terminal voltage of the controllable switch module is too large, the arrester in 2 will be triggered to absorb energy and protect the power electronic components. The power electronic components (such as IGBT/IECT, GTO, etc.) of the controllable switch module are pre-conducted, and their state (on or off) can be controlled. The conduction of power electronic components requires two conditions: the control terminal has a trigger signal, and the device terminal voltage is greater than the threshold voltage. If the control terminal of the power electronic component has a trigger signal, the power electronic component is in a pre-conduction state; if the terminal voltage is greater than the threshold voltage at the same time, the power electronic component is in a conductive state.

After the preset time, the mechanical switch has extinguished the arc, the controllable switch module is turned off, the current is transferred to the transfer branch, and the energy storage element inside the transfer branch is charged; charging makes the voltage of the energy storage element It rises rapidly, triggering the action of the energy-consuming branch and absorbing the remaining energy; when the 1st to nth mechanical switches all recover the insulating ability, the oscillating current generated by the transfer branch is cut off;

After the DC switch device has passed the preset time, the oscillating current generated by the transfer branch has been cut off. The controller sends an instruction to disconnect the first side switch 6 and the second side switch 7, and then sends an instruction to make the first to kth switches. The mechanical switch is closed.

Further, after the DC switchgear is disconnected, the controller sends an instruction to make the device transfer the multi-break DC switchgear whose branch oscillating current is controllable to perform the closing operation process, and judges if the DC switchgear does not receive the system again after closing. If the fault signal of the system is received again, the closing is completed; if the DC switchgear receives the fault signal of the system again after closing, the opening operation process is performed. In the power system, there is a relay protection device, which will determine whether the circuit is a faulty circuit, and if there is a fault, it will send a signal to the switchgear. Faults include grounding, short circuit, open circuit, etc.

Example 1

An embodiment of a three-break DC switchgear with controllable oscillating current in a transfer branch of the present invention is shown in Figure 1. The DC switchgear includes a mechanical switch 1-1, a mechanical switch 1-2, a mechanical switch 1-3, a two-way controllable type Switch module 2, energy storage module 3, energy storage auxiliary module (inductor) 4, arrester 5, first side switch 6 and second side switch 7, wherein the energy storage module 3 is composed of capacitor 3-1, switch 3-2 and Resistors 3-3. The main current branch of the DC switchgear is mainly composed of mechanical switch 1-1, mechanical switch 1-2 and mechanical switch 1-3 in series, one of which is connected in parallel with the bidirectional controllable switch module 2; the transfer branch is powered by energy storage The module 3 is formed in series with the inductor 4, and the transfer branch is connected in parallel to both ends of the mechanical switch 1-1 and the mechanical switch 1-2 through the switch 6. The energy dissipation branch is composed of the arrester 5, which is connected in parallel between the two ends of the three mechanical switches of the main current-passing branch through the series-connected first-side switch 6 and the second-side switch 7.

The bidirectional controllable switch module 2 includes two series-connected IGBTs and a surge arrester, and each IGBT is connected in parallel with a freewheeling diode. If the system needs to be switched off, the controller issues a command, and the bidirectional controllable switch module 2 is pre-conducted, that is, the control terminal of the IGBT provides a conduction signal to make it in the "pre-conduction" state. When the mechanical switch 1-1 is turned on When the arc voltage is greater than the threshold voltage of the bidirectional controllable switch module 2, the two series-connected IGBTs of the bidirectional controllable switch module 2 are in the "on" state, and the current of the mechanical switch 1-1 is transferred to the parallel controllable switch. type switch module. If the terminal voltage of the controllable switch module is too large, the arrester in the bidirectional controllable switch module 2 will be triggered to absorb energy and protect the power electronic components.

The switching process includes:

1) The closing operation process:

As shown in Figure 1, the initial state of the DC switch is in the off position (the mechanical switch 1-1 is closed, and the mechanical switch 1-2, mechanical switch 1-3, switch 6, switch 7 and switch 3-2 are off). If the system needs closing operation, first close the switch 3-2, release the energy stored in the capacitor 3-1 through the resistor 3-3, and complete the pre-closing; after the energy is released, first open the switch 3-2, and then close the Close the switch 6 and the switch 7, and finally close the mechanical switch 1-2 and the mechanical switch 1-3, so that the main current branch is turned on, and the closing operation is completed.

2) Opening operation process:

As shown in Figure 1, the initial state of the DC switch is in the closed position (mechanical switch 1-1, mechanical switch 1-2, mechanical switch 1-3, switch 6 and switch 7 are closed, switch 3-2 is off, and the main current branch carrying rated current). If the system needs to be opened, the controller sends a command to pre-conduct the bidirectional controllable switch module 2, and at the same time sends a command to make the mechanical switch 1-1, mechanical switch 1-2 and mechanical switch 1-3 start to perform the opening operation; when When the arc voltage of the mechanical switch 1-1 is greater than the threshold voltage of the two-way controllable switch module 2, the current through the mechanical switch 1-1 is transferred to the two-way controllable switch module 2, and the mechanical switch 1-1 extinguishes the arc and restores the insulation After the current of the mechanical switch 1-1 is completely transferred to the bidirectional controllable switch module 2, the bidirectional controllable switch module 2 is turned off, and the current of the main current branch is quickly transferred to the capacitor 3 for charging; Before the voltage reaches the withstand voltage value of the two-way controllable switch module 2, the arc of the mechanical switch 1-2 is extinguished and the insulation capacity is restored; the charging makes the voltage of the capacitor 3 rise rapidly, and the rapidly rising voltage will trigger the arrester 5 to act and absorb Remaining energy; when the mechanical switch 1-3 restores the insulation capacity, the mechanical switch 1-3 will cut off the oscillating current generated by the transfer branch, and the transfer branch will have no current passing through, completing the breaking. After the circuit breaker is disconnected, the controller first sends an instruction to disconnect the switch 6 and the switch 7, and then issues an instruction to close the mechanical switch 1-1.

After the circuit breaker is disconnected, the controller sends an instruction to make the device perform the closing process. If the circuit breaker is not closed to the fault circuit, the main current branch carries the rated current of the system, and the closing is completed; if the circuit breaker is closed to the fault circuit, repeat the opening process.

Example 2

As shown in FIG. 2 , it is similar to Embodiment 1, but the bidirectional controllable switch module 2 is replaced with a bridge switch module composed of electronic components, and its working principle and working process are the same as those of Embodiment 1.

Example 3

As shown in Figure 3, it is similar to Embodiment 1, but the transfer branch is directly connected to both ends of the mechanical switch 1-1 and the mechanical switch 1-2 in parallel without passing through the first side switch 6. Its working principle and working process are the same as the implementation Example 1 is the same.

In summary, the present invention relates to a multi-break DC switchgear and a control method with a controllable oscillating current of a transfer branch, which can be applied to the fields of high-voltage, medium-voltage and low-voltage DC power transmission and distribution. The main current branch of the DC switchgear includes multiple mechanical switches, which are connected in series in the transmission and distribution circuit of the power system; the controllable branch is composed of one or more controllable switch modules, which are respectively connected in parallel with one or more mechanical switches ; The transfer branch includes energy storage module and energy storage auxiliary module, and all mechanical switches with controllable switch modules in the transfer branch and the main flow branch form a parallel relationship; In parallel with all mechanical switches. The DC switchgear has sufficient on-off capacity and can act quickly with load, and can be used as a circuit breaker or load switch in unipolar, bipolar and homopolar high-voltage DC transmission lines or medium and low-voltage DC distribution lines. , plays the role of control, protection and isolation of faults, and has the advantages of small size, good economy, high versatility and fast breaking speed.

It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principle of the present invention, but not to limit the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Furthermore, the appended claims of this invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalents of such scope and boundaries.

Claims (9)

1. a controllable multi-fracture DC switchgear of a transfer branch oscillating current, is characterized in that, comprises, main control branch, controllable switch module, transfer branch, energy consumption branch, first side switch (6 ) and the second side switch (7); The main control branch includes the first to nth mechanical switches, which are sequentially connected in series in the power transmission and distribution circuit of the power system; n≥1; The controllable switch module includes first to m controllable switch modules, each controllable switch module can form a parallel relationship with any single or adjacent multiple mechanical switches, and there are a total of k mechanical switches with it. Constitute a parallel relationship; 0<m≤k≤n; The transfer branch is connected in parallel with the series structure of the first to a-th mechanical switches, k≤a≤n; Under the control of the first side switch (6) and the second side switch (7), the two ends of the energy dissipation branch are respectively connected to the two ends of the series structure of the first to nth mechanical switches. 2. The multi-break DC switchgear with controllable oscillating current of a transfer branch according to claim 1, wherein the transfer branch comprises an energy storage module (3) and an energy storage auxiliary module (4) connected in series; The energy storage module (3) is a capacitor or includes: a resistor, a discharge control switch and a capacitive element, the resistor is connected in series with the discharge control switch and then connected in parallel with the capacitive element; the energy storage auxiliary module (4) is a current limiting element. 3 . The multi-break DC switchgear with controllable oscillating current of the transfer branch according to claim 1 or 2 , wherein the energy dissipation branch is a lightning arrester ( 5 ). 4 . 4. The multi-break DC switchgear with controllable oscillating current of the transfer branch according to claim 1 or 2, wherein the transfer branch is controlled by the first side switch (6) to be connected in parallel to the first to ath A series structure of a mechanical switch. 5. The multi-break DC switchgear with controllable oscillating current of the transfer branch according to claim 1 or 2, wherein the controllable switch module comprises a bidirectional controllable switch and a lightning arrester connected in parallel with it; The control switch is a bridge structure or an inverse series structure composed of diodes, IGBTs, IECTs or GTOs. 6. The multi-break DC switchgear with controllable transfer branch oscillating current according to claim 1 or 2, wherein the first side switch (6) and the second side switch (7) are equipped with insulation and Mechanical switch with isolation capability. 7 . The multi-break DC switchgear with controllable oscillating current of the transfer branch according to claim 1 or 2 , wherein the first to mth mechanical switches are isolating switches or vacuum switches. 8 . 8. A control method for a multi-break DC switchgear with controllable transfer branch oscillating current according to one of claims 1 to 7, characterized in that, comprising: 1) The closing operation process: The initial state is that the first to kth mechanical switches are closed, and all other switches are disconnected; If the system needs a closing operation, first control the transfer branch to release energy from the internal energy storage element, and then disconnect the energy release circuit after the energy is released; Close the first side switch (6) and the second side switch (7); At the same time, the remaining n-k mechanical switches are closed to complete the closing operation; 2) Opening operation process: The controller issues an order to make the control terminals of the m controllable switch modules provide a conduction signal to make it in a "pre-conduction" state, and then issues an order to make the 1st to nth mechanical switches perform the opening operation; when any one When the arc voltage of the mechanical switch is greater than the threshold voltage of the parallel controllable switch module, the parallel controllable switch module is in the "on" state, and the current through the mechanical switch is transferred to the parallel controllable switch module; if When the terminal voltage of the controllable switch module exceeds the triggering threshold of the arrester, the arrester in the controllable switch module will be triggered to absorb energy; After the preset time, the mechanical switch has extinguished the arc, the controllable switch module is turned off, the current is transferred to the transfer branch, and the energy storage element inside the transfer branch is charged; charging makes the voltage of the energy storage element It rises rapidly, triggering the action of the energy-consuming branch and absorbing the remaining energy; when the 1st to nth mechanical switches all recover the insulating ability, the oscillating current generated by the transfer branch is cut off; After the DC switch device has passed the preset time, the oscillating current generated by the transfer branch has been cut off, and the controller sends an instruction to disconnect the first side switch (6) and the second side switch (7), and then sends an instruction to make the first side switch (6) and the second side switch (7). Until the kth mechanical switch is closed. 9. The control method according to claim 8, characterized in that: after the DC switchgear completes the breaking, the controller sends an instruction to make the device transfer the multi-break DC switchgear whose branch circuit oscillating current is controllable to perform the closing operation process to judge , if the DC switchgear does not receive the system fault signal again after closing, the closing is completed; if the DC switchgear receives the system fault signal again after closing, the opening operation process is performed.

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