CN114062909B - A DC large current flow test circuit for triggering gap switches - Google Patents

Abstract

The invention discloses a DC large current flow test circuit for triggering a gap switch, and belongs to the high voltage technical field. The test circuit of the present invention includes: a current source branch, and the current source branch includes: a DC charging circuit, an energy discharge branch, an energy storage capacitor, a freewheeling diode, a reactor, an arc time control switch K1, and a protection circuit. Switch K2, voltage divider I and current coil; the voltage source branch includes: DC high voltage generator, recovery voltage adjustment capacitor, recovery voltage rise time adjustment resistor R and voltage divider II. The test voltage of the test circuit of the invention can meet the triggering requirements, the output DC current can meet the current capacity assessment requirements, and the recovery voltage can be applied at the moment of arc extinguishing to meet the rapid insulation recovery assessment requirements. The DC current peak value, arcing time, recovery voltage peak value and rise The time is flexible and adjustable to meet the needs of different test parameters.

Description

A DC large current flow test circuit for triggering gap switches

Technical field

The present invention relates to the field of high voltage technology, and more specifically, to a DC large current flow test circuit for triggering a gap switch.

Background technique

The trigger gap switch is a new type of sub-millisecond fast closing switch that can be used in AC and DC systems. It is often connected in parallel with a circuit breaker as a fast control/protection switch. The trigger gap switch is responsible for quickly triggering the conductor and then closing the circuit breaker to help gap transfer. The current begins to restore the insulation. Taking the trigger gap switch for controlling the controllable self-restoring energy dissipation device of Baihetan-Jiangsu ±800kV DC project as an example, the minimum trigger voltage is 20kV, the current requirement is 30kA/30ms, and the insulation recovery requirement is that it can withstand DC80kV for 1 second after arc extinguishing.

The fracture of the trigger gap switch is composed of high and low voltage electrodes that are fixed and cannot be moved. The current path is maintained by arcing in the gap. If the current is large in a short time, arc ablation may cause the contacts to be burned, and at the same time, a large amount of metal vapor and metal vapor are generated. Gas decomposition products will affect the rapid insulation recovery after arc extinguishing. It is necessary to carry out flow tests to study and verify the large current flow and insulation recovery capabilities. The flow test loop is an important means for the development and performance verification of trigger gap switches.

The flow test loop of the trigger gap switch needs to generate a large current, which is controlled to flow through the trigger gap switch for a short time and then a high-amplitude recovery voltage is applied. The loop capacity is large, the recovery voltage is high, and the control is complex. At present, the AC current test can be carried out with the help of a synthetic circuit for the AC circuit breaker short-circuit breaking test. There is no test circuit available for the DC current test. Directly using the AC short-circuit breaking synthetic circuit cannot meet the requirements, and new test circuits need to be researched and proposed. (Including circuit topology, control methods and equipment parameter determination methods, etc.).

The synthetic circuit for the AC short-circuit breaking test is composed of a low-voltage large-current current source and a high-voltage small-current voltage source. The current source outputs the test current and controls the arcing time. The voltage source applies recovery voltage through ball gap ignition control.

The above loop used to trigger gap DC flow test does not meet the requirements in the following aspects:

1) The output voltage of the current source is usually only 10kV, which is lower than the minimum triggering voltage. It is difficult for the trigger gap switch to trigger conduction reliably. If the test voltage is increased, the power supply capacity will be increased and the test cost will be greatly increased;

2) The current source output is AC current, which is different from DC arc. The equivalent method of AC and DC arc has not yet been determined. If it is transformed into DC output, it will need to add rectification equipment such as large-capacity silicon stack, and the transformation cost will be high. very high;

3) The test circuit relies on the auxiliary switch of the current source branch to interrupt the current to control the arcing time. The auxiliary switch can extinguish the arc and break when the current crosses zero. If the current source is transformed into a DC output, there will be no current zero-crossing point and the auxiliary switch will The current cannot be broken, resulting in the inability to control the arcing time.

Contents of the invention

In response to the above problems, the present invention also proposes a DC large current flow test circuit for triggering the gap switch, including:

Current source branch, the current source branch includes: DC charging circuit, energy discharge branch, energy storage capacitor, freewheeling diode, reactor, arc time control switch K1, protection switch K2, voltage divider I and current coils;

The DC charging circuit is connected to the energy storage capacitor for charging the energy storage capacitor; the energy discharge branch is connected in parallel with the energy storage capacitor to discharge the energy storage capacitor under abnormal conditions; the energy storage capacitor provides test voltage before the gap is triggered. , providing a large current after the gap is connected; the freewheeling diode, the freewheeling diode and the energy storage capacitor are connected in anti-parallel, forming a DC attenuation current loop with the reactor and triggering gap, and the DC attenuation current loop generates a DC attenuation current; arcing time The control switch K1 triggers the gap current by closing the transfer and controls the arcing time; the protection switch K2 restores the voltage by disconnecting the isolation and protects the current source branch; the voltage divider I measures the test voltage; the current coil measures the test current;

Voltage source branch, the voltage source branch includes: a DC high voltage generator, a recovery voltage adjustment capacitor, a recovery voltage rise time adjustment resistor R, and a voltage divider II;

The DC high voltage generator is used to charge the recovery voltage adjustment capacitor; the recovery voltage adjustment capacitor provides the recovery voltage after the arc is extinguished in the gap; when the recovery voltage rise time adjustment resistor R flows through the gap, the output current of the direct high voltage generator is limited to be lower than the short circuit protection current, and After the arc is extinguished in the gap, it forms an RC series circuit with the stray capacitance of the gap fracture to control the rising rate of the gap recovery voltage; the voltage divider II measures the test voltage.

Optionally, the freewheeling diode is connected in anti-parallel at both ends of the energy storage capacitor. After the voltage of the energy storage capacitor is reversed, it is turned on and the energy storage capacitor is bypassed, generating a DC attenuation current in the reactor and gap circuit.

Optionally, the resistance value of the recovery voltage rise time adjustment resistor R is MΩ level, and the voltage source for the recovery voltage is a large-capacity DC high-voltage generator. The large-capacity DC high-voltage generator preloads the recovery voltage before passing through the current. The recovery voltage is immediately applied at the moment when the arc goes out in the gap.

Optionally, the arcing time control switch K1 is connected in parallel at both ends of the reactor in the test circuit. By closing K1, the gap current is transferred, so that the gap arcing time can be controlled without affecting the recovery voltage application rate.

The test voltage of the test circuit of the present invention can meet the triggering requirements, the output DC current can meet the current capacity assessment requirements, and the recovery voltage can be applied at the moment of arc extinguishing to meet the rapid insulation recovery assessment requirements. The DC current peak value, arcing time, recovery voltage peak value and rise The time is flexible and adjustable to meet the needs of different test parameters. At the same time, the test loop has low requirements on power supply capacity, simple and flexible control, and can be set up by test stations, scientific research, and production units.

Description of the drawings

Figure 1 is a circuit topology diagram of the test circuit of the present invention;

Figure 2(a)-(f) is a graph showing the simulation results of the gap flow test process of the test circuit of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete. invention, and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments represented in the drawings does not limit the invention. In the drawings, identical units/elements use the same reference numerals.

Unless otherwise defined, the terms (including scientific and technical terms) used herein have the commonly understood meaning to one of ordinary skill in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have consistent meanings in the context of their relevant fields and should not be understood as having an idealized or overly formal meaning.

The present invention will be further described below in conjunction with the examples:

The test loop circuit topology provided by the test loop of the present invention is shown in Figure 1. The present invention adopts a synthetic loop type.

The current source uses the oscillating discharge of the capacitor bank and the freewheeling of the diode to generate DC attenuation current, and the gap arcing time is selected by controlling the K1 closing time;

The voltage source uses a large-capacity direct high-voltage + MΩ-level protection resistor to apply an exponential rise recovery voltage at the moment of arc extinction. The recovery voltage rise rate is selected by controlling the resistor R and the direct high-voltage output voltage. The composition of the two branches are explained as follows:

The current source branch is composed of a DC charging circuit, an energy discharge branch, an energy storage capacitor, a freewheeling diode, a reactor, an arc time control switch K1, a protection switch K2, a voltage divider I and a current coil. The DC charging circuit is used to charge the energy storage capacitor; the energy discharge branch is used to discharge the energy of the energy storage capacitor when the circuit equipment is abnormal; the energy storage capacitor provides a test voltage before the gap is opened and provides a large current after the gap is opened. ; The freewheeling diode and the energy storage capacitor are connected in anti-parallel, forming a DC attenuation current loop with the reactor and trigger gap; after the arc time control switch K1 is closed, it can transfer the trigger gap current to control the arc time; the circuit breaker K2 is used to control the arcing time when the voltage When the source applies recovery voltage to the test sample, isolate the high-voltage protection current source loop equipment; the voltage divider I is used to measure the test voltage; the current coil is used to measure the test current.

The voltage source branch is composed of a DC high-voltage generator, a recovery voltage adjustment capacitor, a recovery voltage rise time adjustment resistor R, and a voltage divider II. The DC high-voltage generator is used to charge the recovery voltage adjustment capacitor, which provides recovery voltage after the arc is extinguished in the gap; the resistance R of the resistor is MΩ level. When the gap flows, the output current of the DC high-voltage generator is limited to be lower than its short-circuit protection current. After the arc is extinguished in the gap, it forms an RC series connection with the stray capacitance of the gap fracture to control the rising rate of the gap recovery voltage.

The specific method of test circuit control is as follows. Figure 2 shows the expected waveform diagram of the simulation;

Before the test, the energy storage capacitor bank is charged to the test voltage U1, until the high-voltage output rises to the recovery voltage U2, K1 is opened, and K2 is closed.

At 0ms, the trigger gap switch is controlled to be turned on to connect the circuit, and the energy storage capacitor bank is discharged through the reactor, as shown in Figure 2-(a), resulting in an oscillating current with a peak value I, as shown in Figure 2-(b).

The DC current generation method of the freewheeling diode: when the current reaches the peak value, the voltage of the capacitor bank is reversed, and the freewheeling diode is turned on to bypass the capacitor bank, as shown in Figure 2-(c), and a DC attenuation current is generated in the gap, as shown in Figure 2 -(d).

The arcing time control method of the reactor current bypass: control K1 to close at time t according to the current flow time requirement, and transfer the test current to the "reactor + K1" loop, which can control the gap arcing time without affecting the gap application recovery voltage, as shown in Figure 2-(e). The principle of current transfer is that before K1 is closed, the current path is "reactor + freewheeling diode + K2 + gap", in which the gap switch maintains the current path through the arc, the arc resistance is in the order of tens to hundreds of mΩ, and the freewheeling diode is on. The impedance is also on the order of mΩ. After K1 is closed, the "reactor + K1" loop impedance is the contact resistance of the contacts after the circuit breaker is closed. The resistance value is on the order of tens to hundreds of μΩ, which is much lower than the gap + freewheeling diode. branch resistance, therefore, the current will be transferred to the K1 branch to achieve gap arcing time control.

The DC recovery voltage rapid application method of the DC high voltage generator: issue a command to trigger the gap switch and control the circuit breaker K2 to open at the same time. After the current is transferred, the gap switch is triggered to extinguish the arc. At the same time, K2 is disconnected and the direct high voltage is immediately applied to restore the exponential rise. voltage, as shown in Figure 2-(f), K2 can effectively isolate the capacitor bank from recovery voltage. The advantages of this method are low power capacity and simple control. Choose a larger-capacity direct high-voltage generator. Before the gap is triggered, the direct high-voltage generator charges the recovery voltage adjustment capacitor to the recovery voltage. The adjustment capacitor applies high voltage to the gap through the MΩ-level recovery voltage adjustment resistor R. At this time, K2 is in the open state, and the The flow-through equipment and the direct high-voltage generator are isolated and protected; after the gap is connected, the direct high-voltage generator is grounded through the adjusted resistor R. The resistance value should be adjusted so that the ground current is lower than the short-circuit protection value of the direct high-voltage generator so that the direct high-voltage generator maintains high-voltage output; when the gap is extinguished, The adjusting capacitor applies an exponentially rising recovery voltage to the gap fracture through the adjusting resistor R. By selecting a reasonable adjustment of the capacitance value, the recovery voltage rise time is not affected by the corona discharge at the switch K2 fracture and the gap fracture. It is only controlled by the adjusting resistor R and the fracture surface. Determined by the loose capacitance, it can reach the ms level and meet the needs of triggering gap switches.

According to the requirements for triggering the gap switch flow test of a certain DC project, the DC current test circuit is designed. The test voltage U1=30kV, the test current peak value I=30kA, the arcing time t=80ms, the recovery voltage U2=80kV, and the rise time is 100ms. The test requirements are fully met. The rated voltage of the energy storage capacitor in the current source branch is 36kV, the capacitance value is 1mF, and the reactor inductance value is 0.78mH; the rated voltage of the direct high-voltage generator in the voltage source branch is -160kV, the rated current is 10mA, and the resistance R value is 30MΩ. . The results show that the test loop power supply capacity is small, the adjustment is simple and convenient, and it can meet the needs of the trigger gap switch flow test economically and effectively.

The test voltage of the test circuit of the present invention can meet the triggering requirements, the output DC current can meet the current capacity assessment requirements, and the recovery voltage can be applied at the moment of arc extinguishing to meet the rapid insulation recovery assessment requirements. The DC current peak value, arcing time, recovery voltage peak value and rise The time is flexible and adjustable to meet the needs of different test parameters. At the same time, the test loop has low requirements on power supply capacity, simple and flexible control, and can be set up by test stations, scientific research, and production units.

Those skilled in the art will understand that embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment that combines software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein. The solutions in the embodiments of this application can be implemented using various computer languages, such as the object-oriented programming language Java and the literal scripting language JavaScript.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Although the preferred embodiments of the present application have been described, those skilled in the art will be able to make additional changes and modifications to these embodiments once the basic inventive concepts are apparent. Therefore, it is intended that the appended claims be construed to include the preferred embodiments and all changes and modifications that fall within the scope of this application.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies, the present application is also intended to include these modifications and variations.

Claims (4)

1. A dc high current through-current test loop for triggering a gap switch, the loop comprising:

a current source branch, the current source branch comprising: the device comprises a direct current charging loop, an energy discharging branch, an energy storage capacitor, a follow current diode, a reactor, an arcing time control switch K1, a protection switch K2, a voltage divider I and a current coil;

the direct-current charging loop is connected with the energy storage capacitor and is used for charging the energy storage capacitor; the energy discharge branch is connected with the energy storage capacitor in parallel and is used for discharging the energy storage capacitor under abnormal conditions; the energy storage capacitor provides test voltage before gap contact and provides large current after the gap contact; the freewheeling diode, the freewheeling diode and the energy storage capacitor are in anti-parallel connection, and form a direct current attenuation current loop with the reactor and the trigger gap, and the direct current attenuation current loop generates direct current attenuation current; the arcing time control switch K1 controls the arcing time by closing the transfer trigger gap current; the protection switch K2 protects the current source branch by disconnecting the isolation recovery voltage; the voltage divider I measures the test voltage; measuring test current by a current coil;

a voltage source branch, the voltage source branch comprising: the direct-current high-voltage generator, the recovery voltage regulating capacitor, the recovery voltage rise time regulating resistor R and the voltage divider II;

the direct-current high-voltage generator is used for charging the recovery voltage regulating capacitor; the recovery voltage regulating capacitor provides recovery voltage after the gap is quenched; when the recovery voltage rise time adjusting resistor R is in clearance through flow, the direct high-emission output current is limited to be lower than the short-circuit protection current, and forms an RC series circuit with a clearance fracture stray capacitor after clearance arc extinction, so that the rise rate of clearance recovery voltage is controlled; the voltage divider II measures the test voltage.

2. A circuit according to claim 1, wherein the freewheeling diode is anti-parallel connected across the energy storage capacitor, and conducting back in reverse direction of the energy storage capacitor voltage bypasses the energy storage capacitor, creating a dc-damping current in the reactor, gap loop.

3. The circuit of claim 1, wherein the resistance value of the recovery voltage rise time adjusting resistor R is mΩ, the recovery voltage source is a high-capacity dc high-voltage generator, and the recovery voltage is pre-applied before the through-current, and can be applied immediately at the moment of gap arc extinction.

4. The test loop according to claim 1, wherein the test loop is connected with a arcing time control switch K1 in parallel across the reactor, and the clearance current is transferred by closing the switch K1, so that the clearance arcing time can be controlled without affecting the recovery voltage application rate.