Alternating current solid state circuit breaker fault current detection device

Abstract

This invention relates to an AC solid-state circuit breaker fault current detection device, comprising a solid-state circuit breaker and a fault current detection and processing circuit. The detection circuit in the fault current detection and processing circuit is connected in parallel with the solid-state circuit breaker, acquiring the voltage across the main switching device of the solid-state circuit breaker and the voltage across the power semiconductor device on the detection circuit, and obtaining the difference between the two voltages. The fault current detection and processing circuit processes the obtained voltage difference to obtain a characteristic value of the line state, which is then fed back to the solid-state circuit breaker to determine whether the line is in a normal conducting, open, or fault state. This device improves detection accuracy and has a simple structure, making detection convenient.

Description

Technical Field

[0001] This invention belongs to the field of power grid fault protection technology, specifically relating to an AC solid-state circuit breaker fault current detection device. Background Technology

[0002] Circuit breakers, as crucial protective devices for power grids, are primarily used to interrupt fault currents in the grid. Therefore, accurate, effective, and reliable fault current detection circuits are extremely important for the safety of both circuit breakers and the power grid. Compared to traditional mechanical and hybrid circuit breakers, solid-state circuit breakers have a simple structure, are arc-free, and offer rapid breaking capabilities. They are also easily designed as intelligent circuit breakers, making them promising candidates for application in distribution networks.

[0003] AC solid-state circuit breakers (SSDs) have advantages such as small size, simple structure, arc-free operation, fast breaking capacity, and ease of intelligent design, leading to their development in medium and low voltage distribution networks. However, issues related to withstand voltage, capacity, losses, and protection have consistently constrained their development. The primary task of AC SSDs is to interrupt fault currents in the power grid; therefore, accurate and effective fault current detection circuits are crucial. Currently, commonly used fault current detection methods include line current detection and circuit breaker on-state voltage drop detection. Current detection methods utilize sampling resistors and current sensors; on-state voltage drop detection leverages the functional relationship between the on-state voltage drop of a semiconductor device and the current, determining the fault current by detecting the on-state voltage drop, typically using voltage sensors. However, circuit breakers are usually in both on and off states. Directly using the voltage across their terminals results in a large voltage range, insufficient accuracy in on-state voltage drop detection, and susceptibility to misjudgments when in the off-state. Therefore, accurate online on-state voltage drop detection is a vital research direction for SSDs. Summary of the Invention

[0004] The purpose of this invention is to provide an AC solid-state circuit breaker fault current detection device, which is beneficial to improving detection accuracy and has a simple structure and convenient detection.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: an AC solid-state circuit breaker fault current detection device, comprising a solid-state circuit breaker and a fault current detection and processing circuit. The detection circuit in the fault current detection and processing circuit is connected in parallel with the solid-state circuit breaker, and collects the voltage across the main switching device of the solid-state circuit breaker and the voltage across the power semiconductor device on the detection circuit, and obtains the difference between the two voltages. The fault current detection and processing circuit processes the obtained voltage difference to obtain the characteristic value of the line state, and feeds it back to the solid-state circuit breaker, so as to realize the judgment of whether the line is in a normal conducting, open, or fault state.

[0006] Furthermore, the solid-state circuit breaker includes a main switching device Q1 and a control and drive circuit. The main switching device Q1 is a power semiconductor device. The fault current detection and processing circuit includes a detection circuit, a conditioning circuit, and a processing circuit. The detection circuit is connected to the processing circuit through the conditioning circuit, and the processing circuit is connected to the control and drive circuit of the solid-state circuit breaker.

[0007] Furthermore, the main switching device is a thyristor, MOSFET, IGBT, IGCT, SiC-MOSFET, or SiC-IGBT.

[0008] Furthermore, a power semiconductor device conduction voltage drop detection method is used to detect the fault current of an AC solid-state circuit breaker. The detection circuit consists of a power semiconductor device Q2, a current-limiting resistor R2, and a voltage sensor PT. The current-limiting resistor R2 is connected in series with the power semiconductor device Q2 and then in parallel across the solid-state circuit breaker. The voltage sensor PT simultaneously acquires the voltage across both the solid-state circuit breaker and the power semiconductor device Q2. The voltage sensor includes a magnetic core and three windings; the first winding acquires the voltage across the solid-state circuit breaker. u 1(t), the second winding collects the voltage across the power semiconductor device Q2. u 2(t), the voltage of the third winding is the difference between the voltage of the first winding and the voltage of the second winding. u 3(t), the voltage obtained by the detection circuit u 3(t) After passing through the conditioning circuit and processing circuit, the fault current status in the line is obtained. The fault current status is then fed back to the control and drive circuit of the solid-state circuit breaker to control and protect the solid-state circuit breaker.

[0009] Furthermore, a power semiconductor device conduction voltage drop detection method is used to detect the fault current of an AC solid-state circuit breaker. The detection circuit consists of a power semiconductor device Q2, a current-limiting resistor R2, a first voltage sensor PT1, and a second voltage sensor PT2. The current-limiting resistor R2 is connected in series with the power semiconductor device Q2 and then in parallel across the solid-state circuit breaker. The first voltage sensor PT1 collects the voltage across the solid-state circuit breaker. u 1(t), the second voltage sensor PT2 collects the voltage across the power semiconductor device Q2. u 2(t), the corresponding terminals of the secondary windings of the first voltage sensor PT1 and the second voltage sensor PT2 are connected together, and the voltage between the other corresponding terminals is... u 3(t) and simultaneously connected to a conditioning circuit, voltage u 3(t) After passing through the conditioning circuit and processing circuit, the fault current status in the line is obtained. The fault current status is then fed back to the control and drive circuit of the solid-state circuit breaker to control and protect the solid-state circuit breaker.

[0010] Furthermore, the drive signals for power semiconductor devices Q1 and Q2 are the same.

[0011] Furthermore, the resistance of the current-limiting resistor R2 is greater than a set value so that the current flowing through the power semiconductor device Q2 is small enough not to affect the main circuit.

[0012] Compared with existing technologies, the present invention has the following advantages: It provides an AC solid-state circuit breaker fault current detection device. This device determines the operating state of the solid-state circuit breaker by acquiring the difference between the voltage across the solid-state circuit breaker and the voltage across the power semiconductor device in the detection circuit. The detection signal is isolated from the main circuit, improving the accuracy, safety, and real-time performance of the detection, thereby providing accurate fault data for overload, short circuit, and over-temperature protection of solid-state circuit breakers. Furthermore, the device has a simple structure, is convenient to use, and has low implementation cost. Therefore, the present invention has strong practicality and broad application prospects. Attached Figure Description

[0013] Figure 1 This is a circuit diagram of the device according to Embodiment 1 of the present invention.

[0014] Figure 2 This is a circuit diagram of the device in Embodiment 2 of the present invention. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] like Figure 1 , 2As shown, this embodiment provides an AC solid-state circuit breaker fault current detection device, including a solid-state circuit breaker and a fault current detection and processing circuit. The detection circuit in the fault current detection and processing circuit is connected in parallel with the solid-state circuit breaker, and collects the voltage across the main switching device of the solid-state circuit breaker and the voltage across the power semiconductor device on the detection circuit, and obtains the difference between the two voltages. The fault current detection and processing circuit processes the obtained voltage difference to obtain the characteristic value of the line state, and feeds it back to the solid-state circuit breaker to realize the judgment of whether the line is in a normal conducting, open, or fault state.

[0019] Specifically, the solid-state circuit breaker includes a main switching device Q1 and a control and drive circuit. The fault current detection and processing circuit includes a detection circuit, a conditioning circuit, and a processing circuit. The detection circuit is connected to the processing circuit through the conditioning circuit, and the processing circuit is connected to the control and drive circuit of the solid-state circuit breaker. The main switching device Q1 is a power semiconductor device, which can be a thyristor, MOSFET (metal-oxide-semiconductor field-effect transistor), IGBT (insulated-gate bipolar transistor), IGCT (integrated gate commutated thyristor), SiC-MOSFET, or SiC-IGBT, etc.

[0020] This device uses a power semiconductor device conduction voltage drop detection method to detect the fault current of an AC solid-state circuit breaker, and it can be implemented in different ways.

[0021] like Figure 1 As shown, the detection circuit consists of a power semiconductor device Q2, a current-limiting resistor R2, and a voltage sensor PT. The current-limiting resistor R2 is connected in series with the power semiconductor device Q2 and then in parallel across the solid-state circuit breaker. The voltage sensor PT simultaneously acquires the voltage across both the solid-state circuit breaker and the power semiconductor device Q2. The voltage sensor includes a magnetic core and three windings; the first winding acquires the voltage across the solid-state circuit breaker. u 1(t), the second winding collects the voltage across the power semiconductor device Q2. u 2(t), the voltage of the third winding is the difference between the voltage of the first winding and the voltage of the second winding. u 3(t), the voltage obtained by the detection circuit u 3(t) After passing through the conditioning circuit and processing circuit, the fault current status in the line is obtained. The fault current status is then fed back to the control and drive circuit of the solid-state circuit breaker to control and protect the solid-state circuit breaker.

[0022] like Figure 2 As shown, the detection circuit consists of a power semiconductor device Q2, a current-limiting resistor R2, a first voltage sensor PT1, and a second voltage sensor PT2. The current-limiting resistor R2 is connected in series with the power semiconductor device Q2 and then in parallel across the solid-state circuit breaker. The first voltage sensor PT1 collects the voltage across the solid-state circuit breaker.u 1(t), the second voltage sensor PT2 collects the voltage across the power semiconductor device Q2. u 2(t), the corresponding terminals of the secondary windings of the first voltage sensor PT1 and the second voltage sensor PT2 are connected together, and the voltage between the other corresponding terminals is... u 3(t) and simultaneously connected to a conditioning circuit, voltage u 3(t) After passing through the conditioning circuit and processing circuit, the fault current status in the line is obtained. The fault current status is then fed back to the control and drive circuit of the solid-state circuit breaker to control and protect the solid-state circuit breaker.

[0023] The driving terminals of power semiconductor devices Q1 and Q2 are connected to ensure that their driving signals are consistent. The current-limiting resistor R2 has a resistance greater than a set value to ensure that the current flowing through power semiconductor device Q2 is sufficiently small to avoid affecting the main circuit.

[0024] Figure 1 This is a circuit diagram for implementing Embodiment 1 of the present invention. Figure 1 In this circuit, Q1 is the main switching device of the solid-state circuit breaker, typically employing power semiconductor devices such as thyristors, MOSFETs (metal-oxide-semiconductor field-effect transistors), IGBTs (insulated-gate bipolar transistors), IGCTs (integrated gate commutated thyristors), SiC-MOSFETs, and SiC-IGBTs. The fault current detection and processing circuit consists of a voltage sensor PT, power switching device Q2, a current-limiting resistor R2, a conditioning circuit, and a processing circuit. The drive circuits for Q1 and Q2 are identical. The current-limiting resistor R2 limits the current in the detection branch, making the current very small, thus resulting in a small and relatively stable voltage across Q2. The first winding of the voltage sensor PT is connected in parallel across the solid-state circuit breaker to detect the voltage across it. u 1(t), the second winding is connected in parallel across the power semiconductor device Q2 to detect the voltage across Q2. u 2(t), according to the principle of electromagnetic induction, the voltage of the third winding u 3(t) is u 1(t) and u 2(t) Voltage difference. When the solid-state circuit breaker is normally conducting and the current is within the rated range, u The value of 1(t) is small and does not change much. u The value of 2(t) is very small and basically constant, and the voltage u 3(t) is very small; when a line fault occurs, especially a short-circuit fault, the voltage... u 1(t) increases rapidly, while u If the value of 2(t) is small and does not change much, then u The value of 3(t) also increases rapidly, and u The 3(t) value can reflecti The magnitude of 1(t); when the solid-state circuit breaker opens, u 1(t) and u 2(t) are equal. u 3(t) is zero. Therefore, the voltage is zero. u 3(t) can reflect the magnitude of the current in the circuit. u 3(t) The conditioning circuit and processing circuit can determine whether the line is in an open state, a normal state, or a fault state. Once a fault state occurs, the system can give a control signal to control and protect the solid-state circuit breaker through the control and drive circuit.

[0025] Figure 2 This is a circuit diagram for implementing Embodiment 2 of the present invention. Figure 2 In this circuit, Q1 is the main switching device of the solid-state circuit breaker, typically employing power semiconductor devices such as thyristors, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), IGBTs (Insulated-Gate Bipolar Transistors), IGCTs (Integrated Gate Commutated Thyristors), SiC-MOSFETs, and SiC-IGBTs. The fault current detection and processing circuit consists of voltage sensors PT1 and PT2, power switching device Q2, current-limiting resistor R2, conditioning circuit, and processing circuit. Q1 and Q2 have identical drive circuits. The current-limiting resistor R2 limits the current in the detection branch, making the current very small, thus resulting in a small and relatively stable voltage across Q2. This embodiment uses two identical voltage sensors; voltage sensor PT1 is used to detect the voltage across the solid-state circuit breaker. u 1(t), voltage sensor PT2 is used to detect the voltage across power semiconductor device Q2. u 2(t), voltage u 3(t) is u 1(t) and u 2(t) Voltage difference. When the solid-state circuit breaker is normally conducting and the current is within the rated range, u The value of 1(t) is small and does not change much. u The value of 2(t) is very small and basically constant, and the voltage u 3(t) is very small; when a line fault occurs, especially a short-circuit fault, the voltage... u 1(t) increases rapidly, while u If the value of 2(t) is small and does not change much, then u The value of 3(t) also increases rapidly, and u The 3(t) value can reflect i The magnitude of 1(t); when the solid-state circuit breaker opens, u 1(t) and u 2(t) are equal. u 3(t) is zero. Therefore, the voltage is zero. u 3(t) can reflect the magnitude of the current in the circuit.u 3(t) The conditioning circuit and processing circuit can determine whether the line is in an open state, a normal state, or a fault state. Once a fault state occurs, the system can give a control signal to control and protect the solid-state circuit breaker through the control and drive circuit.

[0026] Therefore, the present invention can effectively detect fault current in a circuit, the detection signal is isolated from the main circuit, and the structure is simple and easy to measure.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An alternating current solid state circuit breaker fault current detection device, characterized by, It includes a solid-state circuit breaker and a fault current detection and processing circuit. The detection circuit in the fault current detection and processing circuit is connected in parallel with the solid-state circuit breaker. It collects the voltage across the main switching device of the solid-state circuit breaker and the voltage across the power semiconductor device on the detection circuit, and obtains the difference between the two voltages. The fault current detection and processing circuit processes the obtained voltage difference to obtain the characteristic value of the line state, and feeds it back to the solid-state circuit breaker to realize the judgment of whether the line is in a normal conducting, open, or fault state. The solid-state circuit breaker includes a main switching device Q1 and a control and drive circuit. The main switching device Q1 is a power semiconductor device. The fault current detection and processing circuit includes a detection circuit, a conditioning circuit, and a processing circuit. The detection circuit is connected to the processing circuit through the conditioning circuit, and the processing circuit is connected to the control and drive circuit of the solid-state circuit breaker. A power semiconductor device conduction voltage drop detection method is used to detect the fault current of an AC solid-state circuit breaker. The detection circuit consists of a power semiconductor device Q2, a current-limiting resistor R2, and a voltage sensor PT. The current-limiting resistor R2 is connected in series with the power semiconductor device Q2 and then in parallel across the solid-state circuit breaker. The voltage sensor PT simultaneously collects the voltages across the solid-state circuit breaker and the power semiconductor device Q2. The voltage sensor includes a magnetic core and three windings. The first winding collects the voltage u1(t) across the solid-state circuit breaker, the second winding collects the voltage u2(t) across the power semiconductor device Q2, and the voltage of the third winding is the difference u3(t) between the voltages of the first and second windings. The voltage u3(t) obtained by the detection circuit is processed by a conditioning circuit and a processing circuit to obtain the fault current status in the line. The fault current status is then fed back to the control and drive circuit of the solid-state circuit breaker to control and protect the solid-state circuit breaker. Alternatively, the detection circuit consists of a power semiconductor device Q2, a current-limiting resistor R2, a first voltage sensor PT1, and a second voltage sensor PT2. The current-limiting resistor R2 is connected in series with the power semiconductor device Q2 and then in parallel across the solid-state circuit breaker. The first voltage sensor PT1 collects the voltage u1(t) across the solid-state circuit breaker, and the second voltage sensor PT2 collects the voltage u2(t) across the power semiconductor device Q2. The corresponding terminals of the secondary windings of the first voltage sensor PT1 and the second voltage sensor PT2 are connected together, and the voltage between the other corresponding terminals is u3(t), which is simultaneously connected to a conditioning circuit. After passing through the conditioning circuit and the processing circuit, the voltage u3(t) is used to obtain the fault current status in the line. The fault current status is then fed back to the control and drive circuit of the solid-state circuit breaker to control and protect the solid-state circuit breaker.

2. The AC solid-state circuit breaker fault current detection device according to claim 1, characterized in that, The main switching device is a thyristor, MOSFET, IGBT, IGCT, SiC-MOSFET, or SiC-IGBT.

3. The AC solid-state circuit breaker fault current detection device according to claim 1, characterized in that, The drive signals for power semiconductor devices Q1 and Q2 are the same.

4. The AC solid-state circuit breaker fault current detection device according to claim 1, characterized in that, The resistance of the current-limiting resistor R2 is greater than the set value so that the current flowing through the power semiconductor device Q2 is small enough not to affect the main circuit.

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