Power distribution protection device

Abstract

The invention discloses a power distribution protection device. Comprising a plurality of circuit breakers configured in at least two levels, and the upper-level circuit breaker has a maintenance safety setting function and is used for reducing a current protection set value of the upper-level circuit breaker after the function is started; the upper-stage circuit breaker responds to the opening / closing of the self'maintenance safety setting 'function and sends a first signal / second signal to the lower-stage circuit breaker; the subordinate circuit breaker responds to the first signal sent by the superior circuit breaker and adjusts the current protection set value of the subordinate circuit breaker; and the subordinate circuit breaker responds to a second signal sent by the superior circuit breaker and restores the current protection set value of the subordinate circuit breaker to the current protection set value of the subordinate circuit breaker before the'maintenance safety setting 'function of the superior circuit breaker is started. Compared with the prior art, when the upper-stage circuit breaker enters the working mode of'safety setting maintenance ', the lower-stage circuit breaker is controlled through signal transmission between the upper-stage circuit breaker and the lower-stage circuit breaker, and selective protection of the upper-stage circuit breaker and the lower-stage circuit breaker is ensured.

Description

Technical Field

[0001] The invention relates to a power distribution protection device, belonging to the technical field of power distribution protection. Background Art

[0002] As an important component in the power distribution system, low-voltage circuit breakers undertake the important task of protecting the power distribution network and electrical equipment from the hazards of overload, short circuit and leakage. Circuit breakers have the characteristics of long working hours and complex environment during operation. In order to maintain their good working condition and performance, regular maintenance is required. Usually, when maintaining a circuit breaker, it is necessary to cut off the power supply of the downstream distribution circuit to put the circuit breaker in a power-off state to ensure the safety of maintenance personnel. In some cases, the electrical system must be maintained while powered on, which poses a significant risk of personal injury or property loss. In order to avoid this risk, when maintenance personnel are in the working area of ​​the circuit breaker, the "maintenance safety setting" function of the circuit breaker needs to be turned on. This function can reduce the action time of the circuit breaker and reduce the current protection threshold of the circuit breaker so that the circuit breaker can be opened as soon as possible under low energy conditions when an arc fault occurs to ensure the safety of maintenance personnel.

[0003] The power distribution system usually includes multiple circuit breakers. Especially for multi-level power distribution systems, it is necessary to realize the selective protection of upper and lower level circuit breakers. Usually, the current protection setting value of each level circuit breaker is gradually increased by the setting threshold value. However, when the upper level circuit breaker is maintained live and its "maintenance safety setting" function is turned on, the current protection setting value can be quickly reduced, the action time of the circuit breaker can be reduced, and the safety of the maintenance personnel can be ensured; however, since the current protection setting value of the lower level circuit breaker has not been changed, this destroys the upper and lower level selective protection of the power distribution system. At this time, once the lower level circuit breaker is overloaded or short-circuited, there will be a risk of the circuit breaker tripping, causing unnecessary power outages and property losses. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a distribution protection device that can transmit information to the lower-level circuit breaker while the upper-level circuit breaker realizes the "maintenance safety setting" function, so that it can adjust the current current protection setting value to ensure selective protection of the upper and lower level circuit breakers.

[0005] The present invention specifically adopts the following technical solutions to solve the above technical problems: A power distribution protection device comprises a plurality of circuit breakers configured in at least two levels, wherein an upper-level circuit breaker has a "maintenance safety setting" function for lowering its own current protection setting value after the function is turned on; the upper-level circuit breaker sends a first signal / a second signal to a lower-level circuit breaker in response to turning on / off its own "maintenance safety setting" function; the lower-level circuit breaker adjusts its own current protection setting value in response to the first signal sent by the upper-level circuit breaker; and the lower-level circuit breaker restores its own current protection setting value to its own current protection setting value before the "maintenance safety setting" function of the upper-level circuit breaker is turned on in response to the second signal sent by the upper-level circuit breaker.

[0006] As one of the specific implementation schemes, the lower-level circuit breaker has a "maintenance safety setting" function, the lower-level circuit breaker has a preset first current protection setting value and a second current protection setting value and a third current protection setting value that are lower than the first current protection setting value, and the lower-level circuit breaker is configured as follows: When the "maintenance safety setting" function of the lower circuit breaker is turned off and the first signal sent by the upper circuit breaker is not received, current protection is performed with the first current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned on and the first signal sent by the upper circuit breaker is not received, current protection is performed with the second current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned off and the first signal sent by the upper circuit breaker is received, current protection is performed with the third current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned on and the first signal sent by the upper circuit breaker is received, current protection is performed with the lower of the second current protection setting value and the third current protection setting value.

[0007] As another specific implementation scheme, the lower-level circuit breaker does not have a "maintenance safety setting" function, the lower-level circuit breaker has a preset first current protection setting value and a second current protection setting value lower than the first current protection setting value, and the lower-level circuit breaker is configured as follows: When the lower level circuit breaker does not receive the first signal sent by the upper level circuit breaker, current protection is performed with the first current protection setting value; When the lower-level circuit breaker receives the first signal sent by the upper-level circuit breaker, current protection is performed with the second current protection setting value.

[0008] Preferably, the current protection setting value includes at least one of the following current protection parameter setting values: the action threshold of overload long delay protection, the delay time of overload long delay protection, the action threshold of short circuit short delay protection, the delay time of short circuit short delay protection, the action threshold of short circuit instantaneous protection, the action threshold of ground fault protection, and the delay time of ground fault protection.

[0009] Preferably, the lower level circuit breaker has a first interface circuit for receiving the first signal and the second signal sent by the upper level circuit breaker, and the upper level circuit breaker has a second interface circuit for sending the first signal and the second signal to the lower level circuit breaker.

[0010] Further preferably, the first interface circuit includes a resistor R1, a resistor R2 and an optocoupler U1, one end of the resistor R1 is simultaneously connected to an I / O port of the circuit breaker controller and an output end of the optocoupler U1, the other end of the resistor R1 is connected to the operating voltage VCC, the other output end of the optocoupler U1 is grounded, an input end of the optocoupler U1 is connected to the operating voltage VCC, one end of the resistor R2 is grounded, and the other end of the resistor R2 and the other input end of the optocoupler U1 serve as two input ports of the first interface circuit.

[0011] Further preferably, the second interface circuit includes a resistor R3 and an optocoupler U2, one end of the resistor R3 is connected to an I / O port of the circuit breaker controller, the other end of the resistor R3 is connected to an input end of the optocoupler U2, the other input end of the optocoupler U2 is grounded, and the two output ends of the optocoupler U2 serve as the two output ends of the second interface circuit.

[0012] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The present invention enables information transmission for the "maintenance safety setting" function between the upper and lower circuit breakers. When the upper circuit breaker enters the "maintenance safety setting" working mode, the selective protection of the upper and lower circuit breakers is ensured through signal transmission between the upper and lower circuit breakers, thereby avoiding the risk of circuit breaker tripping when the lower load is overloaded or short-circuited, causing unnecessary power outages and property losses; and through signal transmission between the upper and lower circuit breakers, the current protection setting value of the lower circuit breaker can be automatically reduced, thereby avoiding cumbersome manual settings and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the current protection process of the circuit breaker controller of the present invention; Figure 2 A specific implementation circuit diagram of the circuit breaker controller of the present invention; Figure 3 A schematic diagram of a specific example of the power distribution protection device of the present invention; Figure 4An example of the interface for opening the "Maintain Security Settings" function. DETAILED DESCRIPTION

[0014] In view of the deficiencies in the prior art, the solution of the present invention is to transmit the "maintenance safety setting" function of the upper circuit breaker to the lower circuit breaker to start information. When the upper circuit breaker enters the "maintenance safety setting" working mode, the signal transmission between the upper and lower circuit breakers ensures the selective protection of the upper and lower circuit breakers, avoiding the risk of circuit breaker tripping when the lower load is overloaded or short-circuited, causing unnecessary power outages and property losses; and through the signal transmission between the upper and lower circuit breakers, the current protection setting value of the lower circuit breaker is automatically adjusted to avoid cumbersome manual settings and improve work efficiency.

[0015] The power distribution protection device of the present invention comprises a plurality of circuit breakers configured in at least two levels, wherein the upper circuit breaker has a "maintenance safety setting" function for lowering the current protection setting value of the circuit breaker after the function is turned on; and the upper circuit breaker sends a first signal to the lower circuit breaker in response to the turning on of its own "maintenance safety setting" function, and the lower circuit breaker adjusts its own current protection setting value in response to the first signal sent by the upper circuit breaker; when the "maintenance safety setting" function of the upper circuit breaker is turned off, the upper circuit breaker sends a second signal to the lower circuit breaker in response to the turning off of its own "maintenance safety setting" function, and after receiving the second signal, the lower circuit breaker restores its own current protection setting value to the current protection setting value before the "maintenance safety setting" function of the upper circuit breaker is turned on.

[0016] The upper circuit breaker and the lower circuit breaker are arranged in series in the power supply line. The upper circuit breaker and the lower circuit breaker are relative concepts. The lower circuit breaker is a circuit breaker arranged at the next level of the upper circuit breaker. If the next level of the lower circuit breaker is connected to a circuit breaker, a group of upper and lower circuit breakers is formed. The original lower circuit breaker becomes the upper circuit breaker, and the newly connected circuit breaker is the lower circuit breaker.

[0017] In some embodiments, the first and second signal transmissions in the upper and lower circuit breakers are realized through the interface circuits in the upper and lower circuit breakers, that is, the lower circuit breaker has a first interface circuit for receiving the first signal and the second signal sent by the upper circuit breaker, and the upper circuit breaker has a second interface circuit for sending the first signal and the second signal to the lower circuit breaker. Of course, the implementation method is not limited to this, for example, the signal transmission can also be carried out through wireless communication between the upper and lower circuit breakers.

[0018] When a circuit breaker has both an upper-level circuit breaker and a lower-level circuit breaker, for example, in a multi-layer cascade structure, the controller of the middle-level circuit breaker has both a first interface circuit and a second interface circuit, which can respond to the turning on and off of the "maintenance safety setting" function of the upper-level circuit breaker and adjust the current protection setting value, and transmit signals to the lower-level circuit breaker when it turns on and off the "maintenance safety setting" function, so that the current protection setting value of the lower-level circuit breaker is adjusted accordingly.

[0019] When the lower level circuit breaker also has the "maintenance safety setting" function, the lower level circuit breaker has a preset first current protection setting value and a second current protection setting value and a third current protection setting value that are lower than the first current protection setting value, and the lower level circuit breaker is configured as follows: When the "maintenance safety setting" function of the lower circuit breaker is turned off and the first signal sent by the upper circuit breaker is not received, current protection is performed with the first current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned on and the first signal sent by the upper circuit breaker is not received, current protection is performed with the second current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned off and the first signal sent by the upper circuit breaker is received, current protection is performed with the third current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned on and the first signal sent by the upper circuit breaker is received, current protection is performed with the lower of the second current protection setting value and the third current protection setting value.

[0020] When the lower level circuit breaker does not have the "Maintenance Safety Setting" function, The lower-level circuit breaker has a preset first current protection setting value and a second current protection setting value lower than the first current protection setting value, and the lower-level circuit breaker is configured as follows: When the lower level circuit breaker does not receive the first signal sent by the upper level circuit breaker, current protection is performed with the first current protection setting value; When the lower-level circuit breaker receives the first signal sent by the upper-level circuit breaker, current protection is performed with the second current protection setting value.

[0021] Taking the case where the lower-level circuit breaker also has the "maintenance safety setting" function as an example, the basic working process of the lower-level circuit breaker controller is as follows: Figure 1 As shown, the details are as follows: When the first interface circuit does not receive the first signal sent by the second interface circuit of the upper circuit breaker and the "maintenance safety setting" function is not turned on, the controller of the lower circuit breaker is in a normal working mode, and the current current protection value is the first current protection setting value; If the first interface circuit receives a first signal sent by the second interface circuit of the upper circuit breaker, the controller performs protection according to the third current protection setting value; when the upper circuit breaker turns off the "maintenance safety setting" function, the first interface circuit receives a second signal sent by the second interface circuit of the upper circuit breaker, and the lower circuit breaker resumes protection with the first current protection setting value; If the first interface circuit does not receive the first signal sent by the second interface circuit of the upper circuit breaker, when the circuit breaker turns on the "maintenance safety setting" function, the current circuit breaker controller performs protection according to the second current protection setting value, and when the "maintenance safety setting" function is turned off, the lower circuit breaker resumes protection with the original first current protection setting value; When the first interface circuit receives the first signal sent by the second interface circuit of the upper circuit breaker and the circuit breaker turns on the "maintenance safety setting" function, the current circuit breaker controller selects the lower one from the second current protection setting value and the third current protection setting value for protection.

[0022] A multi-level power distribution protection device can be constructed by configuring a plurality of the above-mentioned circuit breakers in at least two levels and electrically connecting the second interface circuit of the upper-level circuit breaker to the first interface circuit of the lower-level circuit breaker.

[0023] The current protection setting value can be various existing current protection parameter setting values, such as the action threshold of overload long delay protection, the delay time of overload long delay protection, the action threshold of short circuit short delay protection, the delay time of short circuit short delay protection, the action threshold of short circuit instantaneous protection, the action threshold of ground fault protection, the delay time of ground fault protection, etc.

[0024] The first and second interface circuits can be implemented by various existing circuits; the first signal and the second signal can also be arbitrarily designed according to actual conditions, as long as the circuit breaker controller can identify them.

[0025] Figure 2 A specific implementation circuit of the above circuit breaker controller is shown, including a microcontroller and a first interface circuit and a second interface circuit.

[0026] like Figure 2 As shown, the first interface circuit includes a resistor R1, a resistor R2 and an optocoupler U1, one end of the resistor R1 is simultaneously connected to an I / O port of a circuit breaker controller (specifically a microcontroller MCU in the controller, etc.) and an output end of the optocoupler U1, the other end of the resistor R1 is connected to a working voltage VCC, the other output end of the optocoupler U1 is grounded, an input end of the optocoupler U1 is connected to the working voltage VCC, one end of the resistor R2 is grounded, and the other end of the resistor R2 and the other input end of the optocoupler U1 serve as two input ports of the first interface circuit.

[0027] like Figure 2 As shown, the second interface circuit includes a resistor R3 and an optocoupler U2, one end of the resistor R3 is connected to an I / O port of the circuit breaker controller, the other end of the resistor R3 is connected to an input end of the optocoupler U2, the other input end of the optocoupler U2 is grounded, and the two output ends of the optocoupler U2 serve as the two output ends of the second interface circuit.

[0028] Figure 3 The secondary power distribution protection device composed of two of the above-mentioned circuit breakers is shown, and the second interface circuit in the upper circuit breaker is connected to the first interface circuit in the lower circuit breaker. When the upper circuit breaker turns on the "maintenance safety setting" function, the I / O2 port of its microcontroller 1 sends a high-level signal to drive the optocoupler U2 of the second interface circuit to turn on. At this time, the optocoupler U1 of the first interface circuit of the lower circuit breaker receives the short-circuit level signal of the optocoupler U2 and turns on. After receiving the low-level signal, the I / O1 port of its microcontroller 2 reduces the current protection setting value according to the preset value. When the upper circuit breaker turns off the "maintenance safety setting" function, the I / O2 port of its microcontroller 1 sends a low-level signal, and the optocoupler U2 of the second interface circuit is turned off. At this time, the input end of the optocoupler U1 of the first interface circuit of the lower circuit breaker is disconnected, the optocoupler U1 is turned off, and the I / O1 port of its microcontroller 2 receives the high-level signal to restore the original current protection setting value.

[0029] The method of enabling the "Maintenance Safety Setting" function is an existing mature technology, which can adopt the controller operation interface, external passive contact signal, host computer software, etc., and there will be corresponding instructions on the controller when it is enabled. Figure 4 That is, an example is displayed, in which the "Maintenance Safety Setting" function is turned on by operating the intelligent controller human-machine interface. Select "On" to turn on the maintenance safety setting function, and the "ERMS" indicator light on the controller panel is always on.

Claims

1. A power distribution protection device, comprising a plurality of circuit breakers configured in at least two levels, wherein the upper level circuit breaker has a "maintenance safety setting" function for lowering its own current protection setting value after the function is turned on; characterized in that: The upper circuit breaker sends a first signal / a second signal to the lower circuit breaker in response to the on / off of its own "maintenance safety setting" function; the lower circuit breaker adjusts its own current protection setting value in response to the first signal sent by the upper circuit breaker; the lower circuit breaker restores its own current protection setting value to its own current protection setting value before the "maintenance safety setting" function of the upper circuit breaker is turned on in response to the second signal sent by the upper circuit breaker.

2. The power distribution protection device according to claim 1, characterized in that: The lower level circuit breaker has a "maintenance safety setting" function, the lower level circuit breaker has a preset first current protection setting value and a second current protection setting value and a third current protection setting value that are lower than the first current protection setting value, and the lower level circuit breaker is configured as follows: When the "maintenance safety setting" function of the lower circuit breaker is turned off and the first signal sent by the upper circuit breaker is not received, current protection is performed with the first current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned on and the first signal sent by the upper circuit breaker is not received, current protection is performed with the second current protection setting value; When the "maintenance safety setting" function of the lower circuit breaker is turned off and the first signal sent by the upper circuit breaker is received, current protection is performed with the third current protection setting value; When the "maintain safety setting" function of the lower circuit breaker is turned on and the first signal sent by the upper circuit breaker is received, current protection is performed with the lower of the second current protection setting value and the third current protection setting value.

3. The power distribution protection device according to claim 1, characterized in that: The lower level circuit breaker does not have a "maintenance safety setting" function, the lower level circuit breaker has a preset first current protection setting value and a second current protection setting value lower than the first current protection setting value, and the lower level circuit breaker is configured as follows: When the lower level circuit breaker does not receive the first signal sent by the upper level circuit breaker, current protection is performed with the first current protection setting value; When the lower-level circuit breaker receives the first signal sent by the upper-level circuit breaker, current protection is performed with the second current protection setting value.

4. The power distribution protection device according to any one of claims 1 to 3, characterized in that: The current protection setting value includes at least one of the following current protection parameter setting values: the action threshold of overload long delay protection, the delay time of overload long delay protection, the action threshold of short circuit short delay protection, the delay time of short circuit short delay protection, the action threshold of short circuit instantaneous protection, the action threshold of ground fault protection, and the delay time of ground fault protection.

5. The power distribution protection device according to claim 1, characterized in that: The lower level circuit breaker has a first interface circuit for receiving a first signal and a second signal sent by the upper level circuit breaker, and the upper level circuit breaker has a second interface circuit for sending the first signal and the second signal to the lower level circuit breaker.

6. The power distribution protection device according to claim 5, characterized in that: The first interface circuit includes a resistor R1, a resistor R2 and an optocoupler U1, one end of the resistor R1 is simultaneously connected to an I / O port of the circuit breaker controller and an output end of the optocoupler U1, the other end of the resistor R1 is connected to the working voltage VCC, the other output end of the optocoupler U1 is grounded, an input end of the optocoupler U1 is connected to the working voltage VCC, one end of the resistor R2 is grounded, and the other end of the resistor R2 and the other input end of the optocoupler U1 serve as two input ports of the first interface circuit.

7. The power distribution protection device according to claim 5, characterized in that: The second interface circuit includes a resistor R3 and an optocoupler U2, one end of the resistor R3 is connected to an I / O port of the circuit breaker controller, the other end of the resistor R3 is connected to an input end of the optocoupler U2, the other input end of the optocoupler U2 is grounded, and the two output ends of the optocoupler U2 serve as the two output ends of the second interface circuit.

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