Circuit breaker three-phase inconsistency protection device and protection method

Abstract

This disclosure relates to a three-phase inconsistency protection device and method for circuit breakers. The protection device may include: a starting circuit, a time delay circuit, and an output circuit. The starting circuit detects the state of an external circuit breaker and sends a three-phase inconsistency signal to the time delay circuit when the external circuit breaker is in a three-phase inconsistency state. The time delay circuit triggers a time delay action upon receiving the three-phase inconsistency signal and, after the time delay action, drives the output circuit to perform a three-phase inconsistency protection action, such that the time from detecting the state of the external circuit breaker to completing the three-phase inconsistency protection action is a preset time. The preset time is determined based on the AC filtering time of the starting circuit, the time delay action of the time delay circuit after compensation by a preset compensation algorithm, the closing time of the normally open contact of the starting relay, and the closing time of the contact of the output relay. This disclosure ensures the reliability of the three-phase inconsistency protection.

Description

Technical Field

[0001] This disclosure relates to the field of high-voltage power grid technology, and more specifically, to a three-phase inconsistency protection device and method for circuit breakers. Background Technology

[0002] During power system operation, one or two phases of a circuit breaker may disconnect due to various reasons, resulting in incomplete phase operation. If this incomplete phase operation persists for an extended period, it can damage electrical equipment and even trigger protective measures, causing circuit breakers to trip and disconnect normal circuits. Therefore, three-phase inconsistency protection devices are needed to protect the normal operation of the circuit system.

[0003] Currently, the State Grid requires a three-phase inconsistency action time of 3 seconds. In related technologies, taking a three-phase inconsistency protection device composed of discrete time relays and intermediate relays as an example, its three-phase inconsistency action time error in the field is generally within 1%, that is, the error reaches 30ms, and the consistency is poor. Therefore, the reliability of the three-phase inconsistency protection cannot be guaranteed. Summary of the Invention

[0004] To overcome the problems existing in related technologies, this disclosure provides a three-phase inconsistency protection device and protection method for circuit breakers.

[0005] According to a first aspect of the present disclosure, a three-phase inconsistency protection device for a circuit breaker is provided, comprising: a starting circuit, a time delay circuit, and an output circuit; wherein the time delay circuit is connected to the starting circuit and the output circuit respectively;

[0006] The starting circuit is used to detect the status of the external circuit breaker and send a three-phase inconsistency signal to the delay circuit when the external circuit breaker is in a three-phase inconsistency state. The starting circuit has an AC filtering function.

[0007] The time delay circuit is used to trigger a time delay action when the three-phase inconsistency signal is received, and after the time delay action, drive the output circuit to perform a three-phase inconsistency protection action, so that the time from the detection of the external circuit breaker status to the completion of the three-phase inconsistency protection action by the protection device is a preset time; wherein, the time delay circuit includes the excitation coil of the time relay, the output circuit includes the normally open contact of the time relay, the normally open contact of the start relay, the three-phase inconsistency start pressure plate, and the output relay connected in series;

[0008] The preset duration is determined based on the AC filtering duration of the start-up circuit, the delay action duration of the delay circuit after compensation by the preset compensation algorithm, the closing duration of the normally open contact of the start-up relay, and the closing duration of the contact of the output relay; the delay action duration includes the preset delay duration of the time relay and the closing duration of the normally open contact of the time relay.

[0009] Optionally, the starting circuit is further configured to determine that the external circuit breaker is in a three-phase inconsistency state when it is detected that the position of at least one phase of the external circuit breaker is different from that of the other two phases, there is no AC component in the position signal of the external circuit breaker, and the bus voltage meets the preset voltage condition, and to send a three-phase inconsistency signal to the delay circuit.

[0010] Optionally, the startup circuit includes a multi-channel optocoupler isolation circuit;

[0011] The delay circuit is also used to trigger a delay action when the three-phase inconsistency signal is received and the input signal of each optical coupler isolation circuit in the multi-channel optical coupler isolation circuit does not have an AC component and the bus voltage meets the preset voltage condition.

[0012] Optionally, the output circuit further includes a normally open contact of a latching relay;

[0013] The output circuit is also used to perform the three-phase inconsistency protection action when the normally open contact of the time relay is closed, the normally open contact of the start relay is closed, the normally open contact of the lockout relay is closed, and the three-phase inconsistency start pressure plate is engaged.

[0014] According to a second aspect of the present disclosure, a method for protecting against three-phase inconsistency in a circuit breaker is provided, applied to the protection device described in the first aspect, the protection method comprising:

[0015] The starting circuit detects the status of the external circuit breaker and sends a three-phase inconsistency signal to the delay circuit when the external circuit breaker is in a three-phase inconsistent state. The starting circuit has an AC filtering function.

[0016] When the delay circuit receives the three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the output circuit to perform a three-phase inconsistency protection action, so that the time from when the protection device detects the state of the external circuit breaker to when it completes the three-phase inconsistency protection action is a preset time. The delay circuit includes the excitation coil of a time relay, and the output circuit includes the normally open contacts of the time relay, the normally open contacts of the start relay, a three-phase inconsistency start pressure plate, and the output relay connected in series.

[0017] The preset duration is determined based on the AC filtering duration of the start-up circuit, the delay action duration of the delay circuit after compensation by the preset compensation algorithm, the closing duration of the normally open contact of the start-up relay, and the closing duration of the contact of the output relay; the delay action duration includes the preset delay duration of the time relay and the closing duration of the normally open contact of the time relay.

[0018] Optionally, the preset compensation algorithm includes:

[0019] The protection duration is determined by the sum of the delay time of the delay circuit and the closing time of the normally open contact of the starting relay.

[0020] Obtain the protection duration of the most recent N times the protection device has completed three-phase inconsistency protection actions, where N is a positive integer;

[0021] The difference between the N protection durations and the preset protection duration is calculated to obtain N difference values;

[0022] Determine the average value of the N differences, and compensate the average value into the delay action duration of the delay loop.

[0023] Optionally, the starting circuit detects the status of the external circuit breaker and, when the external circuit breaker is in a three-phase inconsistent state, sends a three-phase inconsistency signal to the delay circuit, including:

[0024] When the starting circuit detects that the external circuit breaker meets the following conditions, it sends a three-phase inconsistency signal to the delay circuit:

[0025] At least one phase of the three phases of the external circuit breaker is closed, and there is no AC component in the closed position of each of the three phases;

[0026] At least one phase of the three phases of the external circuit breaker is open, and there is no AC component in each phase open.

[0027] The bus voltage meets the preset voltage conditions, and there is no AC component in the bus voltage;

[0028] There is no reset signal for maintaining three-phase inconsistency, and the reset signal does not contain an AC component.

[0029] Optionally, the output circuit further includes a normally open contact of a latching relay, and the output circuit performs three-phase inconsistency protection operations, including:

[0030] The three-phase inconsistency protection action is executed when the output circuit meets the following conditions:

[0031] The normally open contact of the locking relay is closed when at least one phase of the three phases of the external circuit breaker is in the closed position and there is no AC component in each of the three phases in the closed position.

[0032] The normally open contact of the time relay is closed;

[0033] The normally open contact of the starting relay is closed;

[0034] The three-phase inconsistency start-up pressure plate is engaged.

[0035] Optionally, when the delay circuit receives the three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the output circuit to perform a three-phase inconsistency protection action, including:

[0036] The delay circuit starts timing when it receives the three-phase inconsistency signal;

[0037] When the timing duration reaches the preset delay duration, the normally open contact of the time relay is closed to drive the output circuit to perform a three-phase inconsistency protection action.

[0038] Optionally, when the delay circuit receives the three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the output circuit to perform a three-phase inconsistency protection action, further comprising:

[0039] If, during the timing process, the three-phase inconsistency signal disappears, any optocoupler isolation input signal has an AC component, or the bus voltage does not meet the preset voltage conditions, the timing will stop.

[0040] The technical solution provided by the embodiments of this disclosure includes at least the following beneficial effects: The circuit breaker three-phase inconsistency protection device includes: a starting circuit, a delay circuit, and an output circuit; the delay circuit is connected to both the starting circuit and the output circuit; the starting circuit is used to detect the state of the external circuit breaker and, when the external circuit breaker is in a three-phase inconsistency state, sends a three-phase inconsistency signal to the delay circuit, wherein the starting circuit has an AC filtering function; the delay circuit is used to trigger a delay action upon receiving the three-phase inconsistency signal, and after the delay action, drives the output circuit to perform a three-phase inconsistency protection action, so that the protection device can detect the external circuit breaker... The time from the state of the three-phase inconsistency protection to the completion of the three-phase inconsistency protection action is the preset time. The time delay circuit includes the excitation coil of the time relay, and the output circuit includes the normally open contacts of the time relays connected in series, the normally open contacts of the start relay, the three-phase inconsistency start pressure plate, and the output relay. The preset time is determined based on the AC filtering time of the start circuit, the time delay action time of the time delay circuit after compensation by the preset compensation algorithm, the closing time of the normally open contacts of the start relay, and the closing time of the contacts of the output relay. The time delay action time includes the preset time delay time of the time relay and the closing time of the normally open contacts of the time relay. In other words, the three-phase inconsistency protection action is executed based on a preset duration determined by the AC filtering time of the starting circuit, the delay action time of the delay circuit after compensation by a preset compensation algorithm, the closing time of the normally open contact of the starting relay, and the closing time of the contact of the output relay. Due to the AC filtering process involved in the switching quantity sampling and the closing time of the normally open contacts of the time relay, starting relay, and output relay, if this part of the time is not compensated, an error of more than 40ms will occur between the three-phase inconsistency delay start and the protection output. This will lead to poor setting accuracy, affecting the setting accuracy of the protection device, and thus affecting the three-phase inconsistency protection in the field. Therefore, completing the protection action based on the above-mentioned preset duration can improve the setting accuracy of the protection device, thereby reducing the three-phase inconsistency action time error of the protection device in the field and ensuring the reliability of the three-phase inconsistency protection.

[0041] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0042] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0043] Figure 1 This is a wiring diagram of a three-phase inconsistency protection device for a circuit breaker, according to an exemplary embodiment.

[0044] Figure 2This is a schematic diagram of the structure of an optocoupler circuit according to an exemplary embodiment.

[0045] Figure 3 This is a schematic diagram of the structure of a logic output circuit according to an exemplary embodiment.

[0046] Figure 4 This is a schematic diagram of the control logic of a three-phase inconsistency protection device for a circuit breaker, according to an exemplary embodiment.

[0047] Figure 5 This is a timing diagram of the three-phase inconsistency protection device for a circuit breaker, according to an exemplary embodiment.

[0048] Figure 6 This is a schematic flowchart illustrating a three-phase inconsistency protection method for a circuit breaker according to an exemplary embodiment. Detailed Implementation

[0049] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0050] In the description of this disclosure, it should be noted that the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0051] In the description of this disclosure, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0052] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0053] Figure 1 This is a schematic diagram illustrating the structure of a three-phase inconsistency protection device for a circuit breaker according to an exemplary embodiment, such as... Figure 1 As shown, the three-phase inconsistency protection device 10 for the circuit breaker may include:

[0054] The circuit includes a start-up circuit 11, a delay circuit 12, and an output circuit 13; the delay circuit 12 is connected to the start-up circuit 11 and the output circuit 13, respectively.

[0055] The aforementioned start-up circuit 11 is used to detect the status of the external circuit breaker, and when the external circuit breaker is in a three-phase inconsistent state, it sends a three-phase inconsistent signal to the aforementioned delay circuit 12, wherein the aforementioned start-up circuit has an AC filtering function.

[0056] The aforementioned delay circuit 12 is used to trigger a delay action when the aforementioned three-phase inconsistency signal is received, and after the delay action, drive the aforementioned output circuit 13 to perform a three-phase inconsistency protection action, so that the time from when the aforementioned protection device 10 detects the state of the external circuit breaker to when it completes the three-phase inconsistency protection action is a preset time; wherein, the aforementioned delay circuit 12 includes the excitation coil of the time relay, the aforementioned output circuit 13 includes the normally open contact of the aforementioned time relay, the normally open contact of the starting relay, the three-phase inconsistency starting pressure plate, and the output relay connected in series.

[0057] The preset duration is determined based on the AC filtering duration of the start-up circuit 11, the delay operation duration of the delay circuit 12 after compensation by the preset compensation algorithm, the closing duration of the normally open contact of the start-up relay, and the closing duration of the contact of the output relay; the delay operation duration includes the preset delay duration of the time relay and the closing duration of the normally open contact of the time relay.

[0058] For example, the aforementioned startup circuit 11 may include a highly selective isolated optocoupler input circuit. Optionally, this isolated optocoupler input circuit may consist of nine independent optocoupler isolation circuits. Each optocoupler isolation circuit may include at least one optocoupler and an isolation voltage divider circuit connected to the input terminal of the optocoupler. The isolation voltage divider circuit includes a general-purpose diode, a Zener diode, and a voltage divider current-limiting resistor. The output terminal of the optocoupler is connected to the input terminal of the processor. The nine optocoupler isolation circuits are respectively used to receive the A / B / C three-phase close signal, the A / B / C three-phase open signal, the signal bus signal, the three-phase inconsistency action signal, and the three-phase inconsistency action holding reset circuit from the external circuit breaker.

[0059] As an example, please refer again. Figure 1The aforementioned delay circuit 12 may include a processor 121 and multiple logic output circuits 122 corresponding to relays. The input terminal of the processor 121 is connected to the aforementioned start-up circuit 11, and the output terminal of the processor 121 is connected to the multiple logic output circuits 122 corresponding to the relays. Each logic output circuit 122 includes an excitation coil group for a relay and is used to control its corresponding relay according to the output signal of the processor 121. Optionally, the multiple relays may include time relays, output relays, latching relays, alarm relays, etc. Optionally, the working principle of the processor 121 can refer to the principle of the STM32G070CBT6 chip. The function of the processor is to: collect the input signal of the start-up circuit 11, analyze and process it, and after the conditions for delay action are met, the processor will start timing and issue a timing indication. After the timing time reaches the delay duration, it will output a signal to the output circuit 13 and drive the output circuit 13 to perform a three-phase inconsistency protection action.

[0060] As an example, such as Figure 2 As shown, the isolated optocoupler input circuit (hereinafter also referred to as the optocoupler circuit) includes: an optocoupler U1 and an isolation voltage divider circuit, wherein the optocoupler U1 is connected to the isolation voltage divider circuit and the processor 121 respectively.

[0061] The aforementioned isolation voltage divider circuit includes: a general-purpose diode D1, a first current-limiting resistor R1, a second current-limiting resistor R2, a first Zener diode D2, a second Zener diode D3, and a protection diode D4.

[0062] The positive terminal of the general-purpose diode D1 is used to connect to the three-phase auxiliary switch of the external circuit breaker, and the negative terminal of the general-purpose diode D1 is connected to the negative terminal of the first Zener diode D2 through the first current-limiting resistor R1.

[0063] The positive terminal of the first Zener diode D2 is connected to the first input terminal of the optocoupler U1 and the negative terminal of the protection diode D4, respectively.

[0064] The positive terminal of the second Zener diode D3 is connected to the second current-limiting resistor R2, and the negative terminal of the second Zener diode D3 is connected to the first output terminal of the optocoupler U1 and the positive terminal of the protection diode D4.

[0065] The second input terminal of the aforementioned optocoupler U1 is connected to the power supply circuit (i.e., power supply voltage VCC), and the second output terminal of the aforementioned optocoupler U1 is connected to the aforementioned processor 121. Optionally, the aforementioned optocoupler circuit further includes:

[0066] The first pull-down resistor R3 has its first end connected to the second output terminal of the optocoupler U1 and the processor 121, respectively, and its second end grounded.

[0067] In practical applications, the conduction current of optocoupler U1 is approximately 2mA. When a signal is input to the optocoupler circuit, the general-purpose diode D1 first acts as a reverse connection protection mechanism, preventing damage to the optocoupler if the input terminal is connected incorrectly. Through the cooperation of the first current-limiting resistor R1, the first current-limiting resistor R2, the first Zener diode D2, and the second Zener diode D3, the input current is ensured to be within the appropriate operating range of the optocoupler. The current-limiting resistors reduce the overall input return current, while the Zener diodes protect the current-limiting resistors by reducing the voltage across them and preventing overheating, thus ensuring more reliable operation of the input circuit.

[0068] Among them, the protection diode D4 is a clamping diode, which is used to clamp the first input terminal of the optocoupler U1 (such as...). Figure 2 (pin 1 in the middle) and the first output terminal (such as pin ... Figure 2 The voltage at pin 2 is fixed within a suitable range.

[0069] The second output terminal of optocoupler U1 (e.g.) Figure 2 Pin 4 of the optocoupler has a first pull-down resistor R3, which keeps the output signal at a low level when there is no input to the optocoupler, preventing the processor 121 from acquiring interference signals. When there is a signal input, the transistor in the optocoupler U1 turns on, outputting a high level to the input terminal of the processor 121.

[0070] Optionally, the general-purpose diode D1 and the protection diode D4 mentioned above can be of type 1N4007, and the resistance values ​​of the first current-limiting resistor R1 and the second current-limiting resistor R2 can be equal, with a resistance value of 24K at a DC voltage level of 220V.

[0071] Optionally, the general-purpose diode D1 and the first Zener diode D2 can be of the same type, specifically a 62V Zener diode, and the optocoupler U1 can be a TLP127. Under these parameter conditions, the operating voltage of the optocoupler circuit can be guaranteed to be between 55% and 70% of the rated voltage, thus meeting the requirement of 55% to 70% operating voltage for three-phase inconsistent circuits specified in the national standard.

[0072] As can be seen, in this embodiment, the optocoupler circuit replaces the relay coil coupling method in the traditional three-phase inconsistency protection circuit. By adopting optocoupler, the signal response speed and consistency can be improved significantly. The conduction time of the optocoupler is on the order of nanoseconds, while the energization time of the relay coil is on the order of microseconds.

[0073] As an example, the logic output circuits corresponding to multiple relays may include the logic output circuits corresponding to time relays. Taking the logic output circuits corresponding to time relays as an example, such as... Figure 3 As shown, the logic output circuit corresponding to this time relay may include:

[0074] The NAND gate U2, AND gate U3, pull-up resistor R4, second pull-down resistor R5, third pull-down resistor R6, third current limiting resistor R7, transistor Q1, and the excitation coil group of the aforementioned time relay RL1.

[0075] The first and second input terminals of the NAND gate circuit U2 are both connected to the first terminal of the pull-up resistor R4. The second terminal of the pull-up resistor R4 is connected to the power supply circuit (i.e., the power supply voltage VCC). The second input terminal of the NAND gate circuit U2 is connected to the output terminal of the processor 121. The output terminal of the NAND gate circuit U2 is connected to the first input terminal of the AND gate circuit U3.

[0076] The second input terminal of the AND gate circuit U3 is connected to the processor 121 and the first terminal of the second pull-down resistor R5, respectively. The second terminal of the second pull-down resistor R5 is grounded. The output terminal of the AND gate circuit U3 is connected to the first terminal of the third pull-down resistor R6 and the first terminal of the third current limiting resistor R7, respectively.

[0077] The second end of the third pull-down resistor R6 is grounded together with the emitter of the transistor Q1.

[0078] The second end of the third current-limiting resistor R7 is connected to the base of the transistor Q1.

[0079] The collector of transistor Q1 is connected to the power supply through the excitation coil group of time relay RL1. The part of the logic output circuit other than the excitation coil group of time relay RL1 can be considered a separate logic circuit. By connecting different relay excitation coil groups to this logic circuit, different logic output circuits corresponding to different relays can be formed.

[0080] In practical applications, please refer to [the relevant documentation] again. Figure 3 The input terminals of the NAND gate U2 (hereinafter referred to as NAND gate U2) and the AND gate U3 (hereinafter referred to as AND gate U3) are both connected to the output terminal of the processor 121.

[0081] When the processor 121 does not detect a three-phase inconsistency signal, pins 1 and 2 of the NAND gate U2 receive a high-level signal from the processor output. The pull-up resistor R4 ensures that OUT_EN is reliably held at a high level. At this time, the NAND gate U2 outputs a low-level signal to pin 1 of the AND gate U3. Simultaneously, pin 2 of the AND gate U3 receives a low-level signal from the processor 121. The pull-down resistor R5 ensures that OUT1 is reliably held at a low level. At this time, the AND gate U3 outputs a low-level signal, at which point transistor Q1 is in a non-conducting state, and time relay RL1 is not energized.

[0082] When a three-phase inconsistency signal is detected and the delay time is reached, the input signals of the NAND gate and the AND gate flip. The original OUT_EN signal flips from a high-level input to a low-level input. At this time, the NAND gate U1 outputs a high-level signal to the input terminal 1 of the AND gate, and the OUT1 signal flips from a low-level input to a high-level input. At this time, the AND gate U2 outputs a high-level signal, which, after passing through the current-limiting resistor R7, provides a high-level signal to the base of the transistor Q1, causing Q1 to conduct. The excitation coil of the time relay RL1 is thus energized, causing the normally open contact of the relay RL1 connected in series in the output circuit 13 to close.

[0083] As can be seen, in this embodiment, NAND gates U2 and AND gate U3 in the logic output circuit receive two independent input signals from processor 121, and the states of these two signals are opposite under any circumstances. Even in the worst-case scenario, the probability of both input signals being interfered with simultaneously and causing a change in the input signal states of NAND gates U2 and AND gate U3 is extremely low. Furthermore, pull-up and pull-down resistors are added to the input terminals of both NAND gates U2 and AND gate U3 to ensure the reliability of the output logic circuit. With the logic output circuit in this embodiment, the reliability of the time relay contacts is guaranteed, fundamentally solving the possibility of malfunction of the time relay in the current three-phase inconsistency protection circuit, and greatly improving the reliability of the three-phase inconsistency protection device 10.

[0084] As an example, please refer again. Figure 1 The aforementioned output circuit 13 can consist of a three-phase inconsistent starting pressure plate 134, a normally open contact 131 of a time relay, a normally open contact 134 of a lockout relay, an excitation coil 133 of an output relay, and a 5W starting circuit for the output relay. Figure 1 (Not shown in the text) constitutes the structure.

[0085] In practical applications, when the processor 121 detects that at least one phase of both the normally open and normally closed contacts is closed, the processor 121 triggers a delay action to start timing. After the preset setting time is reached, the time relay in the control logic output circuit closes the normally open contact of the time relay connected in series with the output circuit 13, thereby energizing the output relay to perform a three-phase trip of the circuit breaker and ensure the safe operation of the external circuit breaker. Optionally, the closing of the above-mentioned blocking relay's open contact can also be combined with the closing of the normally open contact of the time relay as a condition for the output circuit 13 to perform a three-phase inconsistency protection action. Among them, the 5W starting circuit of the output relay is used to enable the output circuit 13 to have a starting power of ≥5W. Only when the power of the output circuit 13 is greater than or equal to 5W can the output relay be energized, opening the three-phase inconsistency protection open contact, as well as the alarm contact and three-phase inconsistency action holding contact required by the State Grid standard.

[0086] As an example, the protection device 10 may further include a power supply circuit, which is connected to the processor 121 and the logic output circuit respectively.

[0087] Optionally, the power supply circuit can be a dual-isolated 5V output power supply circuit that meets electromagnetic compatibility level 4. This power supply circuit may include a surge suppression circuit, a rectifier and filter circuit, an isolated buck circuit, and a low dropout regulator (LDO) unit. In practical applications, after the input power enters the power supply circuit, it first passes through an EMC suppression circuit composed of a thermistor, varistor, common-mode inductor, and safety capacitor to ensure a stable output to the rectifier circuit. The rectifier and filter circuit, using a rectifier bridge and electrolytic capacitors, sets the input power to a smooth and stable DC power supply to meet the requirements of the buck circuit. The isolated buck circuit then steps down the input power to two isolated 5V DC outputs: one 5V output powers the relay in output circuit 13, and the other powers the LDO unit. The LDO unit steps down the 5V to a stable 3.3V LDO power supply to the main control unit and logic output unit. The operating principle of the LDO unit can be referenced from the principle of the AMS1117 chip.

[0088] As an example, the protection device 10 may also include a human-machine interaction circuit, which is connected to the processor 121.

[0089] As an example, the human-machine interaction circuit may include buttons, a display, and indicator lights. Optionally, the display may be an LCD display, and the indicator lights may be LED lights. Through the buttons and the display, the user can set functions such as delay time, backlight time of the display, and voice. The display and indicator lights can remind the user of the three-phase inconsistency status of the external circuit breaker.

[0090] In some embodiments, the starting circuit 11 is further configured to determine that the external circuit breaker is in a three-phase inconsistent state when it is detected that the position of at least one phase of the external circuit breaker is different from that of the other two phases, there is no AC component in the position signal of the external circuit breaker, and the bus voltage meets the preset voltage condition, and to send a three-phase inconsistent signal to the delay circuit 12.

[0091] For example, in practical applications, the signal input by the optocoupler can indicate the status of the external circuit breaker. For instance, when the external circuit breaker is operating normally in the closed state, the opening signal input by the optocoupler in the starting circuit 11 is at a low level, and the closing signal is at a high level. The bus voltage signal input by the optocoupler is at a high level, the three-phase inconsistency action signal input by the optocoupler is at a low level, and the three-phase inconsistency action holding reset signal of the optocoupler input circuit is at a low level.

[0092] In this embodiment, when the input signal of the starting circuit 11 meets the following 5 conditions, the external circuit breaker can be in a three-phase inconsistent state, and a three-phase inconsistent signal can be sent to the delay circuit 12.

[0093] (1) When one or two of the optocoupler input closing signals change to a high level, and at the same time one or two of the optocoupler input opening signals change to a low level, the circuit breaker is currently in a three-phase inconsistent state.

[0094] (2) When the signal bus signal of the optocoupler input is at a high level, it is determined that the bus voltage meets the preset voltage condition, and at this time it is shown that the signal bus voltage is normal.

[0095] (3) When the three-phase inconsistency output signal of the optocoupler input is low, it indicates that the three-phase inconsistency output relay inside the device is in normal working condition.

[0096] (4) When the external three-phase inconsistency hold reset signal of the optocoupler input is low, there is no external three-phase inconsistency hold reset signal.

[0097] (5) No AC component was detected at all optocoupler inputs. At this time, the requirements for anti-AC maloperation in the three-phase inconsistency protection circuit in the national standard can be met.

[0098] In other words, the starting circuit 11 will only generate a three-phase inconsistency signal and send it to the processor when the following conditions are met: at least one phase of the external circuit breaker is in a different position than the other two phases, no AC component is detected in the position signal, and the bus voltage is normal.

[0099] The startup circuit 11 has an AC filtering function, which can be used to detect the AC component in the input signal. The AC component detection filtering algorithm is as follows: the AC frequency is 50Hz or 60Hz. The characteristic of 50Hz AC is a sine wave with a period of 20ms. First, the reverse polarity protection diode of the optocoupler input circuit rectifies the sine wave into a small wave with only a positive half-cycle, which is reflected in the input terminal of the optocoupler circuit as a regularly fluctuating voltage. Second, the operating voltage of the optocoupler circuit is 55%–70% reliable for identification, and the processing speed of the optocoupler circuit is at the nanosecond level, much smaller than one cycle of the AC signal. Within this positive half-cycle of 10ms, the AC input signal will go through a process of 0V to 220V and then back to 0V, which is reflected in the optocoupler output signal as a process of low level to high level and then back to low level. The processor processes the signal using the algorithm. If there are two discontinuous high-level inputs within one cycle of the AC signal, i.e., within 20ms, it is determined that there is an AC component, and the processor starts timing.

[0100] In some implementations, the startup circuit 11 includes a multi-channel optocoupler isolation circuit.

[0101] The aforementioned delay circuit 12 is also used to trigger a delay action when the aforementioned three-phase inconsistency signal is received and the input signal of each of the aforementioned multi-channel optocoupler isolation circuits does not have an AC component and the bus voltage meets the preset voltage condition.

[0102] In practical applications, the processor will only perform the delay operation when the delay loop 12 meets the following conditions: a three-phase inconsistency signal is received, any optocoupler-isolated input signal has no AC component, and the bus voltage is valid. If, during the delay process, the three-phase inconsistency signal disappears, any optocoupler-isolated input signal has an AC component, or the bus voltage becomes invalid, the timing will immediately stop.

[0103] In some embodiments, the aforementioned output circuit 13 also includes a normally open contact of a latching relay.

[0104] The aforementioned output circuit 13 is also used to perform the aforementioned three-phase inconsistency protection action when the normally open contact of the aforementioned time relay is closed, the normally open contact of the aforementioned start relay is closed, the normally open contact of the aforementioned lockout relay is closed, and the aforementioned three-phase inconsistency start pressure plate is engaged.

[0105] In practical applications, when the timing duration of the delay circuit 12 reaches the preset delay duration and meets the conditions for the time relay to open, the processor will drive the time relay to be energized, changing the normally open contact of the time relay to the normally closed state.

[0106] When at least one phase is detected to be in the closed position, the processor will drive the latching relay to be energized, changing the normally open contact of the latching relay to a normally closed contact.

[0107] When the starting power of output circuit 13 is greater than or equal to 5W, after a three-phase inconsistency occurs and the time relay contacts are closed, the normally open contacts of the lockout relay are closed, and the output pressure plate is connected, the 5W starting relay will close. After the 5W starting relay closes, it will drive the output relay to be energized and simultaneously open the normally open contacts of the output relay to close, thus performing the three-phase inconsistency protection action.

[0108] When the 5W starting relay is energized, the normally open contact of another 5W starting relay feeds back a three-phase inconsistency action signal to the processor. The processor can monitor whether the three-phase inconsistency protection action has been completed, and can also compensate for the three-phase inconsistency action time to make the three-phase inconsistency action time more accurate.

[0109] After the three-phase inconsistency protection action is completed, the position input signal of the optocoupler isolation circuit will change to the open position. At this time, the processor cancels the drive of all relays and controls the protection device 10 to return to the initial state.

[0110] In summary, the control logic of the protection device 10 in this embodiment can be as follows: Figure 4 As shown, according to Figure 4 It is known that in the starting circuit 11, the starting circuit 11 will send a three-phase inconsistency signal to the delay circuit 12 only when the following conditions are met: at least one phase of the three phases of the external circuit breaker is closed and there is no AC component in the closed phase of each phase; at least one phase of the three phases of the external circuit breaker is open and there is no AC component in the open phase of each phase; the bus voltage is normal and there is no AC component in the bus voltage; there is no reset signal for maintaining the three-phase inconsistency operation and there is no AC component in the reset signal.

[0111] In the delay circuit 12, timing begins after receiving a three-phase inconsistency signal, and after the timing duration reaches the preset delay duration, the normally open contact of the time relay in the control output circuit 13 is closed.

[0112] In the output circuit 13, the three-phase inconsistency protection action is only performed when the normally open contact of the aforementioned blocking relay is detected to be closed, wherein the normally open contact of the aforementioned blocking relay is closed when at least one of the three phases of the aforementioned external circuit breaker is in the closed position and there is no AC component in the closed position of each of the three phases; the normally open contact of the aforementioned time relay is closed; the normally open contact of the aforementioned starting relay (hereinafter also referred to as the power relay) is closed; and the aforementioned three-phase inconsistency starting pressure plate is engaged, thereby realizing the three-phase inconsistency protection.

[0113] In addition, due to the existence of the AC filtering algorithm for switch quantity sampling, time relay, power circuit start relay, and normally open contact closing time of the three-phase output relay, if this part of the time is not compensated, there will be an error of more than 40ms between the three-phase inconsistency delay start and the protection output. This will result in poor setting accuracy, affect the setting accuracy of this device, and thus affect the three-phase inconsistency protection on site.

[0114] The AC component detection and filtering algorithm is as follows: The frequency of the AC power is 50Hz or 60Hz. The characteristic of 50Hz AC power is a sine wave with a period of 20ms. First, the reverse polarity protection diode in the optocoupler input circuit can rectify the sine wave into a dome wave with only a positive half-cycle, which is reflected in the input terminal of the optocoupler circuit as a voltage with regular up and down fluctuations. Second, the operating voltage of the optocoupler circuit is 55%~70% reliable identification, and the processing speed of the optocoupler circuit is at the nanosecond level, which is much smaller than one cycle of the AC signal. Within this positive half-cycle of 10ms, the AC input signal will go through a process of 0V to 220V and then back to 0V, which is reflected in the optocoupler output signal as a process of low level to high level and then back to low level. The processor times the duration of the high level. If there are two discontinuous high level inputs within one cycle of AC, that is, 20ms, it is judged that there is an AC component. At this time, the processor does not perform timing operation.

[0115] Therefore, the three-phase inconsistency protection timing of this protection device can be Figure 5As shown, specifically, the processor's timing starts when a three-phase inconsistency signal is detected. Since the AC filtering algorithm requires 20ms to detect the three-phase inconsistency signal, this time is denoted as T0. After detecting the three-phase inconsistency signal, the processor starts timing. The expected three-phase inconsistency protection time T is the time preset through the human-machine interface of this device. The time from the start delay to the closing of the normally open contact of the time relay is denoted as T1. After the normally open contact of the time relay closes, the 5W start relay is activated. When the normally open contact of the 5W start relay closes, one pair of normally open contacts of the power relay will open a three-phase inconsistency action signal, which is input to the processor via a switch. The time from the closing of the time relay to the closing of the power relay is denoted as T2. The time from the start delay to the closing of the power relay is denoted as T3. After the power relay closes, the output relay is energized, and a three-phase inconsistency trip signal is issued. The time from energization to the output is denoted as T4. In other words, the expected three-phase inconsistency protection duration, i.e., the preset duration, is T. The AC filtering duration of the aforementioned starting circuit is T0, the delay operation duration of the aforementioned delay circuit after compensation by the preset compensation algorithm is T1, the closing duration of the normally open contact of the aforementioned starting relay is T2, and the closing duration of the contact of the aforementioned output relay is T4. The delay operation duration T1 includes the preset delay duration of the time relay (i.e.,... Figure 5 The software delay of the time relay and the closing time of the normally open contact of the time relay.

[0116] T = T0 + T1 + T2 + T4, where this time period is the preset duration from the delay to the output, and it is expected that the actual three-phase inconsistency protection duration will infinitely approach this duration. T4 can also be considered as the operating time of the output relay; in this invention, based on the manufacturer's datasheet and actual measurements, this value is a setpoint of 7ms.

[0117] Since T4 is a discrete value with an error of 1ms, which meets the error requirements of the three-phase inconsistency device, this invention fixes this time as a constant. Therefore, it can be concluded that T3 is also an expected constant value, T3 = T - T0 - T4.

[0118] Additionally, T3 = T1 + T2, where this timeframe represents the actual time the processor can read from within the device. T2 is the activation time of the startup circuit, which, due to hardware circuit design, is a discrete value within a certain range under different environments. Therefore, we need to control T1 to meet accuracy requirements. T1, on the other hand, is the actual timing time performed internally by the processor, and this part is controllable. This embodiment primarily calculates and compensates for T1 using a preset compensation algorithm.

[0119] For example, the processor will compensate T1 using a preset compensation algorithm. Specifically, the compensation algorithm may include:

[0120] The time from the last three-phase inconsistency signal to the power relay closing is denoted as T3'. This time is compared to the expected T3 value, and the difference is calculated as Tx1 = T3 - T3'. This three-phase inconsistency operation is repeated N times. The processor will obtain data from Tx1 to Txn. The processor continuously sums the most recent 5 data points and calculates the average, which is denoted as... This data represents the controllable error time in the three-phase inconsistency delay, which the processor will then... The compensation is carried over to the next delay time T1 to ensure that the accuracy of the three-phase inconsistency delay meets the requirement of 0.2% * setting time + 5ms.

[0121] As can be seen, in this embodiment, the three-phase inconsistency protection device for the circuit breaker includes: a starting circuit, a delay circuit, and an output circuit; the delay circuit is connected to both the starting circuit and the output circuit; the starting circuit is used to detect the state of the external circuit breaker and, when the external circuit breaker is in a three-phase inconsistency state, sends a three-phase inconsistency signal to the delay circuit, wherein the starting circuit has an AC filtering function; the delay circuit is used to trigger a delay action upon receiving the three-phase inconsistency signal, and after the delay action, drives the output circuit to perform a three-phase inconsistency protection action, so that the protection device can complete the three-phase inconsistency protection action from detecting the state of the external circuit breaker to completing the three-phase inconsistency protection action. The duration of the phase inconsistency protection action is a preset duration; wherein, the time delay circuit includes the excitation coil of the time relay, the output circuit includes the normally open contacts of the time relays connected in series, the normally open contacts of the start relay, the three-phase inconsistency start pressure plate, and the output relay; wherein, the preset duration is determined based on the AC filtering duration of the start circuit, the time delay action duration of the time delay circuit after compensation by the preset compensation algorithm, the closing duration of the normally open contacts of the start relay, and the closing duration of the contacts of the output relay; the time delay action duration includes the preset time delay duration of the time relay and the closing duration of the normally open contacts of the time relay. In other words, the three-phase inconsistency protection action is executed using a preset duration determined by the AC filtering time of the starting circuit, the delay action time of the delay circuit after compensation by a preset compensation algorithm, the closing time of the normally open contact of the starting relay, and the closing time of the contact of the output relay. Due to the AC filtering process involved in the switching quantity sampling and the closing time of the normally open contacts of the time relay, starting relay, and output relay, if this time is not compensated, an error of more than 40ms will occur between the three-phase inconsistency delay start and the protection output. This will lead to poor setting accuracy, affecting the setting accuracy of the protection device and thus impacting the on-site three-phase inconsistency protection. Therefore, using the aforementioned preset duration to complete the protection action can improve the setting accuracy of the protection device, thereby reducing the three-phase inconsistency action time error in the field and ensuring the reliability of the three-phase inconsistency protection. Furthermore, the fully isolated input and output circuit can meet the electromagnetic compatibility level four requirements, effectively preventing interference from the on-site electromagnetic environment.

[0122] Figure 6 This is a flowchart illustrating a three-phase inconsistency protection method for a circuit breaker according to an exemplary embodiment. This three-phase inconsistency protection method can be applied to the protection device 10 of the above embodiment, and the method may include:

[0123] 110. The above-mentioned starting circuit detects the status of the external circuit breaker and sends a three-phase inconsistency signal to the above-mentioned delay circuit when the external circuit breaker is in a three-phase inconsistent state. The above-mentioned starting circuit has an AC filtering function.

[0124] 120. When the above-mentioned delay circuit receives the above-mentioned three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the above-mentioned output circuit to perform a three-phase inconsistency protection action, so that the time from the detection of the status of the external circuit breaker to the completion of the three-phase inconsistency protection action by the above-mentioned protection device is a preset time.

[0125] The aforementioned preset duration is determined based on the AC filtering duration of the aforementioned start-up circuit, the delay action duration of the aforementioned delay circuit after compensation by the preset compensation algorithm, the closing duration of the normally open contact of the aforementioned start-up relay, and the closing duration of the contact of the aforementioned output relay; the aforementioned delay action duration includes the preset delay duration of the aforementioned time relay and the closing duration of the normally open contact of the aforementioned time relay.

[0126] The specific implementation methods of steps 110 to 120 can be referred to the working process of the circuit breaker three-phase inconsistency protection device described above, so they will not be repeated here.

[0127] In some implementations, the aforementioned preset compensation algorithm includes:

[0128] The protection duration is determined by the sum of the delay time of the aforementioned delay circuit and the closing time of the normally open contact of the aforementioned starting relay.

[0129] Obtain the protection duration of the above protection device for the most recent N times it completed the three-phase inconsistency protection action, where N is a positive integer.

[0130] Calculate the difference between the above protection duration N times and the preset protection duration to obtain N difference values;

[0131] Determine the average value of the above N differences, and compensate the above average value into the delay action duration of the above delay loop.

[0132] The preset compensation algorithm can refer to the way the processor compensates for T1 using the preset compensation algorithm in the above embodiment, so it will not be described in detail here. The protection duration of the most recent N completed three-phase inconsistency protection actions can correspond to the time T3' from the last three-phase inconsistency signal to the closing time of the power relay in the above embodiment, and the preset protection duration can correspond to the expected T3 value in the above embodiment.

[0133] In some implementations, step 110 may include the following specific implementations:

[0134] When the aforementioned starting circuit detects that the aforementioned external circuit breaker meets the following conditions, it sends a three-phase inconsistency signal to the aforementioned delay circuit.

[0135] At least one of the three phases of the aforementioned external circuit breaker is in the closed position, and there is no AC component in the closed position of each of the three phases.

[0136] At least one phase of the three phases of the aforementioned external circuit breaker is open, and there is no AC component in any of the three phases.

[0137] The bus voltage meets the preset voltage conditions, and there is no AC component in the bus voltage.

[0138] There is no reset signal for maintaining three-phase inconsistency, and the aforementioned reset signal does not contain an AC component.

[0139] The specific implementation of step 110 can be found in the control flow of the start-up circuit in the above embodiments, and therefore will not be repeated here.

[0140] In some implementations, step 120 may include the following specific implementations:

[0141] The three-phase inconsistency protection will be activated when the above-mentioned output circuit meets the following conditions:

[0142] The normally open contact of the aforementioned locking relay is closed when at least one of the three phases of the aforementioned external circuit breaker is in the closed position, and when there is no AC component in the closed position of each of the three phases.

[0143] The normally open contact of the aforementioned time relay is closed.

[0144] The normally open contact of the aforementioned starting relay is closed.

[0145] The above three phases are inconsistent, so the starting pressure plate is put into operation.

[0146] The specific implementation of step 120 can be found in the control flow of the output circuit in the above embodiments, and therefore will not be repeated here.

[0147] In some embodiments, step 120 may further include:

[0148] The aforementioned delay circuit begins timing upon receiving the aforementioned three-phase inconsistency signal.

[0149] When the timing duration reaches the preset delay duration, the normally open contact of the aforementioned time relay is closed to drive the aforementioned output circuit to perform a three-phase inconsistency protection action.

[0150] In some embodiments, step 120 may further include:

[0151] If, during the timing process, the three-phase inconsistency signal disappears, any optocoupler isolation input signal has an AC component, or the bus voltage does not meet the preset voltage conditions, the timing will stop.

[0152] As can be seen, the three-phase inconsistency protection method proposed in this embodiment can effectively avoid problems such as AC signal interference and inaccurate position signals in the field, achieving high reliability, good selectivity, and strong anti-maloperation capability for three-phase inconsistency protection. Simultaneously, the algorithm compensation based on a high-performance microprocessor ensures that the time setting accuracy of the three-phase inconsistency protection circuit reaches 0.2% * setting time + 5ms, greatly improving the accuracy of the setting time and further enhancing the reliability and accuracy of the three-phase inconsistency protection circuit.

[0153] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0154] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0155] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A three-phase inconsistency protection device for a circuit breaker, characterized in that, include: The system includes a start-up circuit, a delay circuit, and an output circuit; the delay circuit is connected to both the start-up circuit and the output circuit. The starting circuit is used to detect the status of the external circuit breaker and send a three-phase inconsistency signal to the delay circuit when the external circuit breaker is in a three-phase inconsistency state. The starting circuit has an AC filtering function. The time delay circuit is used to trigger a time delay action when the three-phase inconsistency signal is received, and after the time delay action, drive the output circuit to perform a three-phase inconsistency protection action, so that the time from the detection of the external circuit breaker status to the completion of the three-phase inconsistency protection action by the protection device is a preset time; wherein, the time delay circuit includes the excitation coil of the time relay, the output circuit includes the normally open contact of the time relay, the normally open contact of the start relay, the three-phase inconsistency start pressure plate, and the output relay connected in series; The preset duration is determined based on the AC filtering duration of the start-up circuit, the delay action duration of the delay circuit after compensation by the preset compensation algorithm, the closing duration of the normally open contact of the start-up relay, and the closing duration of the contact of the output relay; the delay action duration includes the preset delay duration of the time relay and the closing duration of the normally open contact of the time relay. The starting circuit detects the status of the external circuit breaker and, when the external circuit breaker is in a three-phase inconsistent state, sends a three-phase inconsistent signal to the delay circuit, including: When the starting circuit detects that the external circuit breaker meets the following conditions, it sends a three-phase inconsistency signal to the delay circuit: At least one phase of the three phases of the external circuit breaker is closed, and there is no AC component in the closed position of each of the three phases; At least one phase of the three phases of the external circuit breaker is open, and there is no AC component in each phase open. The bus voltage meets the preset voltage conditions, and there is no AC component in the bus voltage; There is no reset signal for maintaining three-phase inconsistency, and the reset signal does not contain an AC component; The output circuit also includes a normally open contact of a latching relay, and the output circuit performs three-phase inconsistency protection actions, including: The three-phase inconsistency protection action is executed when the output circuit meets the following conditions: The normally open contact of the locking relay is closed when at least one phase of the three phases of the external circuit breaker is in the closed position and there is no AC component in each of the three phases in the closed position. The normally open contact of the time relay is closed; The normally open contact of the starting relay is closed; The three-phase inconsistency start-up pressure plate is engaged.

2. The circuit breaker three-phase inconsistency protection device according to claim 1, characterized in that, The starting circuit is also used to determine that the external circuit breaker is in a three-phase inconsistent state when it is detected that the position of at least one phase of the external circuit breaker is different from that of the other two phases, there is no AC component in the position signal of the external circuit breaker, and the bus voltage meets the preset voltage condition, and to send a three-phase inconsistent signal to the delay circuit.

3. The circuit breaker three-phase inconsistency protection device according to claim 1, characterized in that, The startup circuit includes multiple optocoupler isolation circuits; The delay circuit is also used to trigger a delay action when the three-phase inconsistency signal is received and the input signal of each optical coupler isolation circuit in the multi-channel optical coupler isolation circuit does not have an AC component and the bus voltage meets the preset voltage condition.

4. The circuit breaker three-phase inconsistency protection device according to claim 1, characterized in that, The output circuit also includes a normally open contact of a lockout relay; The output circuit is also used to perform the three-phase inconsistency protection action when the normally open contact of the time relay is closed, the normally open contact of the start relay is closed, the normally open contact of the lockout relay is closed, and the three-phase inconsistency start pressure plate is engaged.

5. A method for protecting against three-phase inconsistency in a circuit breaker, characterized in that, Applied to the protective device as described in any one of claims 1-4, characterized in that it comprises: The starting circuit detects the status of the external circuit breaker and sends a three-phase inconsistency signal to the delay circuit when the external circuit breaker is in a three-phase inconsistent state. The starting circuit has an AC filtering function. When the delay circuit receives the three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the output circuit to perform a three-phase inconsistency protection action, so that the time from when the protection device detects the state of the external circuit breaker to when it completes the three-phase inconsistency protection action is a preset time. The delay circuit includes the excitation coil of a time relay, and the output circuit includes the normally open contacts of the time relay, the normally open contacts of the start relay, a three-phase inconsistency start pressure plate, and the output relay connected in series. The preset duration is determined based on the AC filtering duration of the start-up circuit, the delay action duration of the delay circuit after compensation by the preset compensation algorithm, the closing duration of the normally open contact of the start-up relay, and the closing duration of the contact of the output relay; the delay action duration includes the preset delay duration of the time relay and the closing duration of the normally open contact of the time relay.

6. The three-phase inconsistency protection method for circuit breakers according to claim 5, characterized in that, The preset compensation algorithm includes: The protection duration is determined by the sum of the delay time of the delay circuit and the closing time of the normally open contact of the starting relay. Obtain the protection duration of the most recent N times the protection device has completed three-phase inconsistency protection actions, where N is a positive integer; The difference between the N protection durations and the preset protection duration is calculated to obtain N difference values; Determine the average value of the N differences, and compensate the average value into the delay action duration of the delay loop.

7. The three-phase inconsistency protection method for circuit breakers according to claim 5, characterized in that, When the delay circuit receives the three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the output circuit to perform a three-phase inconsistency protection action, including: The delay circuit starts timing when it receives the three-phase inconsistency signal; When the timing duration reaches the preset delay duration, the normally open contact of the time relay is closed to drive the output circuit to perform a three-phase inconsistency protection action.

8. The three-phase inconsistency protection method for circuit breakers according to claim 7, characterized in that, When the delay circuit receives the three-phase inconsistency signal, it triggers a delay action, and after the delay action, it drives the output circuit to perform a three-phase inconsistency protection action, further comprising: If, during the timing process, the three-phase inconsistency signal disappears, any optocoupler isolation input signal has an AC component, or the bus voltage does not meet the preset voltage conditions, the timing will stop.

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