Grounding blade locking method, system and switchgear cabinet using the same

Abstract

The present application relates to the technical field of power system five-prevention locking, and is a grounding knife locking method and system and a switch cabinet adopting the same, which acquires the opening and closing state signal of the circuit breaker of the superior outgoing line interval, acquires the current detection signal of the line side of the superior outgoing line interval, acquires the voltage detection signal and / or live state signal of the incoming line side of the local side, performs logical judgment according to the opening and closing state signal, the current detection signal and the voltage detection signal and / or live state signal, and only when the superior outgoing line interval circuit breaker is in the opening position, the current of the line side is less than or equal to the preset threshold, and there is no voltage on the incoming line side of the local side, the locking of the closing operation of the grounding knife is released; otherwise, the locking of the closing operation of the grounding knife is maintained. The present application can avoid the risk of closing the live grounding knife or the live grounding knife by introducing the dual criteria of the position of the superior circuit breaker and the line current and combining the voltage judgment of the local side.

Description

Technical Field

[0001] This invention relates to the field of five-prevention interlocking technology in power systems, and is a grounding switch interlocking method, system, and switchgear using the system. Background Technology

[0002] In power systems, the five-prevention interlocking device is a crucial safety measure to prevent electrical misoperation. Its core functions include preventing accidental entry into energized compartments, preventing the opening and closing of disconnecting switches under load, preventing the application of grounding wires while energized, preventing the closing of switches with grounding wires connected, and preventing accidental opening and closing of circuit breakers. Among these, the closing operation of the grounding switch (or grounding switch) involves switching equipment to a grounded state, and its safety directly affects the personal safety of operators and the stable operation of the power grid. However, existing five-prevention systems primarily rely on the status information of the local equipment in their grounding switch interlocking logic design, failing to adequately consider the operating status of the upstream power supply side, thus posing serious safety hazards.

[0003] In actual operation, a typical serious misoperation incident occurred during the maintenance transfer process of a 35kV user terminal station. In this incident, maintenance personnel, while performing maintenance transfer operations on the incoming line bay, failed to confirm whether the line was already de-energized and blindly closed the grounding switch of the incoming line bay. Although the circuit breaker of the outgoing bay of the upstream substation had been disconnected at this time, the line side was still energized through other paths (such as backfeeding from the opposite substation or induced current on the line). The instantaneous closing of the grounding switch caused a direct phase-to-ground short circuit, and the overcurrent protection of the upstream substation tripped, resulting in a momentary loss of voltage for all users supplied by the substation and causing a large-scale power outage. The accident investigation found that the existing five-prevention system only detects the position of the circuit breaker and the position of the isolating switch on the local side, and cannot know the status of the circuit breaker of the upstream outgoing bay or the actual energization of the line. Therefore, it cannot effectively block the grounding switch closing operation.

[0004] In existing technologies, although some substations are equipped with live line display devices, these signals are typically only used to alert operators whether there is power on site and are not interlocked with the five-prevention interlocking system. Operators can only rely on visual observation of the live line display device to determine whether the line is energized. This reliance on manual judgment is highly subjective and prone to oversight, especially at night or in inclement weather conditions, where the probability of misjudgment increases significantly. Furthermore, some improved solutions attempt to introduce a single-sided current criterion as an interlocking condition, but they do not consider the coordination of the upstream circuit breaker position signal, and the current threshold setting is too high, making it susceptible to misjudgment due to the zero drift of the current transformer. Therefore, the reliability of the interlocking remains insufficient. Summary of the Invention

[0005] This invention provides a grounding switch interlocking method, system, and switchgear using the system, which overcomes the shortcomings of the prior art. It can effectively solve the technical problem that the existing five-prevention interlocking system cannot effectively interlock the grounding switch closing operation because it only relies on the local state, which poses a serious safety hazard.

[0006] One of the technical solutions of the present invention is achieved through the following measures: a grounding switch interlocking method, comprising the following steps: acquiring the opening and closing status signal of the upstream outgoing line compartment circuit breaker; acquiring the current detection signal of the line side of the upstream outgoing line compartment; acquiring the voltage detection signal and / or energized status signal of the incoming line side; performing logical judgment based on the opening and closing status signal, the current detection signal, and the voltage detection signal and / or energized status signal; releasing the interlocking of the grounding switch closing operation when and only when the upstream outgoing line compartment circuit breaker is in the open position, the current on the line side is less than or equal to a preset threshold, and there is no voltage on the incoming line side of the present side simultaneously; otherwise, maintaining the interlocking of the grounding switch closing operation.

[0007] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The aforementioned preset threshold may include a secondary current value of 0.01A.

[0008] The specific methods for determining whether there is voltage on the incoming line side may include: acquiring the secondary voltage of the incoming line voltage transformer on this side, and determining that there is no voltage when the secondary voltage value is lower than a preset voltage threshold; and / or acquiring the energized status signal output by the energized display device on this side, and determining that there is no voltage when the energized status signal is a no-voltage signal.

[0009] The above-mentioned method of locking the grounding switch closing operation may include: connecting the normally open node of the electrical locking node in series with the grounding switch closing circuit; when the judgment result is a locking signal, the normally open node is opened to cut off the closing circuit; when the judgment result is an allow signal, the normally open node is closed to conduct the closing circuit.

[0010] The above-mentioned method of locking the grounding switch closing operation may also include: blocking the grounding switch operating mechanism by locking the latch of the electromagnetic lock to prevent its operation, and the electromagnetic lock is driven by the result of logic judgment.

[0011] The second technical solution of the present invention is achieved through the following measures: a grounding switch interlocking system, comprising: a signal acquisition unit, used to acquire the opening and closing status signal of the upstream outgoing line compartment circuit breaker, the current detection signal on the line side of the upstream outgoing line compartment, and the voltage detection signal or energized status signal on the incoming line side of this side; a logic judgment unit, connected to the signal acquisition unit, used to perform logical judgment based on the opening and closing status signal, the current detection signal, and the voltage detection signal or energized status signal, and output a closing permission signal if and only if the upstream outgoing line compartment circuit breaker is in the open position, the current on the line side is less than or equal to a preset threshold, and there is no voltage on the incoming line side of this side; otherwise, output an interlocking signal; and an interlocking execution unit, connected to the logic judgment unit, used to prevent the grounding switch closing operation when the interlocking signal is received, and to release the restriction on the grounding switch closing operation when the closing permission signal is received.

[0012] The following are further optimizations and / or improvements to the second technical solution of the above invention: The aforementioned signal acquisition unit may include a current signal acquisition subunit, a voltage signal acquisition subunit, and a energized status signal receiving subunit. The current signal acquisition subunit can be used to acquire the secondary current value of the upstream outgoing line bay line side, the voltage signal acquisition subunit can be used to acquire the secondary voltage value of the incoming voltage transformer on this side, and the energized status signal receiving subunit can be used to receive the energized status signal output by the energized display device on this side.

[0013] The aforementioned interlocking execution unit may include an electrical interlocking subunit and a mechanical electromagnetic interlocking subunit; the electrical interlocking subunit may be used to connect its interlocking contacts into the grounding switch closing circuit to cut off the closing circuit, and the mechanical electromagnetic interlocking subunit may be used to stop the grounding switch operating mechanism by locking the locking tongue to prevent its operation.

[0014] The third technical solution of the present invention is achieved through the following measures: a switch cabinet, comprising: a cabinet body; a grounding switch disposed in the cabinet body; and the aforementioned grounding switch interlocking system, wherein the interlocking execution unit of the grounding switch interlocking system is connected to the operating mechanism of the grounding switch; the interlocking execution unit prevents the grounding switch from closing when the logic judgment unit outputs an interlocking signal, and allows the grounding switch to close when it outputs an allow closing signal.

[0015] The following are further optimizations and / or improvements to the third technical solution of the above invention: The operating mechanism of the aforementioned grounding switch may include an operating handle or an operating shaft; the interlocking execution unit of the grounding switch interlocking system may be installed on the cabinet at the position corresponding to the operating mechanism; the signal input terminal of the signal acquisition unit may be connected to the distribution terminal of the upstream outgoing line bay and / or the voltage monitoring terminal of the local incoming line.

[0016] This invention constructs a complete "upper-level + local-level" multi-dimensional interlocking logic by introducing three conditions: the position signal of the upstream outgoing circuit breaker, the current criterion of the upstream outgoing circuit breaker line side, and the voltage criterion of the local incoming circuit breaker line side. The interlocking of the grounding switch is only released when the upstream circuit breaker confirms tripping, the line confirms no current, and the local side confirms no voltage. If any condition is not met, the interlocking remains, thus avoiding the risks of disconnecting or closing the grounding switch with the grounding switch on, significantly improving the operational safety of the power system. The use of a low current threshold of 0.01A effectively eliminates zero-drift interference from the current transformer, preventing interlocking failure due to signal mis-triggering. For different scenarios with and without voltage transformers on site, two adaptation methods are provided: voltage transformer secondary side voltage acquisition and live display device signal acquisition, facilitating retrofitting and implementation in substations with different voltage levels and configurations. A dual-redundant actuator, combining an electrical interlocking node connected in series with the closing circuit and a mechanical electromagnetic lock tongue blocking mechanism, allows for independent and parallel operation of two interlocking mechanisms. Either mechanism can independently prevent the grounding switch from closing if the condition is not met. Even if one mechanism fails due to a malfunction, the other can still function as an interlocking unit, significantly improving the fault tolerance and reliability of the interlocking system. After integrating this interlocking system into the entire switchgear, fully automated control from signal acquisition and logic judgment to interlock execution can be achieved without manual intervention, eliminating the possibility of human error and misoperation. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the grounding bar locking method according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the grounding bar locking system according to an embodiment of the present invention. Detailed Implementation

[0019] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0020] The present invention will be further described below with reference to embodiments: Example 1: As Figure 1As shown, this embodiment provides a grounding switch interlocking method, including the following steps: acquiring the opening / closing status signal of the upstream outgoing line compartment circuit breaker; acquiring the current detection signal on the line side of the upstream outgoing line compartment; acquiring the voltage detection signal and / or energized status signal on the incoming line side; performing logical judgment based on the opening / closing status signal, current detection signal, and voltage detection signal and / or energized status signal; releasing the interlocking of the grounding switch closing operation when and only when the upstream outgoing line compartment circuit breaker is in the open position, the current on the line side is less than or equal to a preset threshold, and there is no voltage on the incoming line side; otherwise, maintaining the interlocking of the grounding switch closing operation. The logical judgment of this method is executed by a microcomputer-based five-prevention system or a dedicated measurement and control device, acquiring each input signal through hard contacts or communication. The preset threshold can be set according to the rated value of the secondary side of the current transformer. The triple-condition AND logic ensures that the grounding switch closing operation can only be performed under the safe conditions that the upstream circuit breaker has been disconnected, there is no current in the line, and there is no voltage on this side. If any condition is not met, the system will be locked, which completely avoids the accident of disconnecting the grounding switch while it is energized due to operator misjudgment or the single logic of the five-prevention system. At the same time, it solves the technical problem that the existing five-prevention system cannot detect the energized status of the upstream side by relying only on the status of this side.

[0021] In this embodiment, the preset threshold is a secondary current value of 0.01A. This threshold is lower than the zero drift value of conventional protection devices, ensuring that the current criterion will not be misjudged as having current due to slight zero drift of the current transformer under normal operating conditions, making the no-current judgment more reliable. At the same time, the electrical quantity corresponding to 0.01A is extremely small, which can sensitively reflect whether the line is truly energized. When there is a weak induced current or leakage current in the line, if the current value exceeds 0.01A, the system can still accurately identify and maintain the lockout, avoiding a safety blind spot caused by setting the threshold too high. The setting of this threshold takes into account the error characteristics of different types of current transformers and actual field operating data.

[0022] In this embodiment, the specific method for determining whether there is voltage on the incoming line side is as follows: The secondary voltage of the incoming line voltage transformer on this side is collected; when the secondary voltage value is lower than a preset voltage threshold, it is determined that there is no voltage. And / or, the energized status signal output by the energized display device on this side is acquired; when the energized status signal is a no-voltage signal, it is determined that there is no voltage. The secondary voltage of the voltage transformer is divided into two types: 57.7V (open delta or phase voltage) and 100V (line voltage). The preset voltage threshold can be set to 10% to 20% of the rated secondary voltage, that is, when the voltage is lower than 5.77V to 11.54V or 10V to 20V, it is determined that there is no voltage. For stations without incoming line voltage transformers, the no-voltage output signal of the energized display device can be accessed via RS485 communication or hard contact. The two methods can be used individually or mutually verified. When both methods are accessed simultaneously, if either method determines that there is voltage, the interlocking is maintained, further improving safety.

[0023] In this embodiment, the method for interlocking the grounding switch closing operation is as follows: the normally open node of the electrical interlocking node is connected in series with the grounding switch closing circuit; when the judgment result is an interlocking signal, the normally open node opens to cut off the closing circuit; when the judgment result is an allow signal, the normally open node closes to connect the closing circuit. The rated current of the electrical interlocking node should not be less than the maximum conducting current of the grounding switch closing circuit. Typically, an intermediate relay node or a solid-state relay output node with a rated current of 5A to 10A is selected. This method directly acts on the closing circuit, achieving interlocking at the electrical level. It has a fast response speed and reliable disconnection. Even if the operator presses the closing button, the circuit has already been disconnected, and the grounding switch cannot operate.

[0024] In this embodiment, the grounding switch closing operation is performed by locking the grounding switch operating mechanism with the latch of the electromagnetic lock to prevent its operation. The electromagnetic lock is driven by the result of a logic judgment. The power control circuit of the electromagnetic lock is connected in series with the output node of the logic judgment unit. When the logic judgment result is locked, the electromagnetic lock is de-energized or energized, driving the latch to extend and engage with the corresponding lock hole or slot on the operating mechanism, preventing the operating handle or operating shaft from rotating. The rated voltage of the electromagnetic lock can be DC24V, DC110V, or AC220V, selected according to the control power supply voltage of the switchgear. The protection level is not lower than IP54 to adapt to the environment inside the switchgear.

[0025] In this invention, the grounding switch interlocking method employs a triple-criteria AND logic interlocking scheme: "the upper-level outgoing line bay circuit breaker is in open position, there is no current on the upper-level outgoing line bay line side, and there is no voltage on the local incoming line." The interlocking of the grounding switch closing operation is only released when all three conditions are met simultaneously; otherwise, the interlocking remains in place. Specifically, the current criterion uses a secondary current value of 0.01A as the threshold for determining whether the circuit is energized or de-energized. This threshold is lower than the current zero-drift value of conventional protection and control devices, ensuring reliable determination of a de-energized state when the line is truly without current. It also effectively filters zero-drift interference caused by residual magnetism, ambient temperature changes, or device aging in the current transformer, preventing signal mis-triggers that could lead to interlocking failure. This significantly improves the accuracy of the criteria and the reliability of the system operation. The opening and closing status signals of the upstream outgoing circuit breaker can be obtained through hard contact (i.e., directly connected to the switch input module of the measurement and control device via control cable) or communication (obtained from the station control layer or bay layer equipment of the upstream substation via industrial standard protocols such as IEC61850 or Modbus). The two methods can be flexibly selected according to the on-site communication conditions and the renovation budget, which is especially suitable for situations where communication conditions are limited in the renovation of old substations.

[0026] This invention provides two methods for determining the absence of voltage on the local side, depending on whether an incoming voltage transformer (PT) is configured on-site: For substations or switchgear with an incoming PT, the secondary voltage value of the PT (rated value of 57.7V or 100V) can be collected for judgment. When the secondary voltage value is lower than a preset voltage threshold, it is determined to be without voltage, with accurate judgment and rapid response; For terminal stations or user stations without an incoming PT, the "energized / de-energized" switch signal output by the local energized display device can be used for judgment, without the need for additional PT installation, resulting in low modification cost and short construction period. Both methods can reliably determine the absence of voltage on the local side, with strong applicability, covering various substation scenarios with different voltage levels and equipment configurations, greatly facilitating the modification and implementation of existing five-prevention systems. In addition, when both signal sources exist simultaneously, they can be used for mutual verification, further improving the reliability of the no-voltage criterion. The interlocking actuator adopts a dual redundancy architecture combining electrical interlocking and mechanical electromagnetic locks, with the two mechanisms operating independently in parallel and serving as backups for each other. Electrical interlocking is achieved by inputting the logic judgment result into the grounding switch closing circuit via a normally open node: when the logic judgment result is "allowing closing," the normally open node closes, the grounding switch closing circuit is connected, and electrical closing operation is permitted; when the logic judgment result is "locking," the normally open node remains open, the closing circuit is cut off, and even if the operator presses the closing button, the grounding switch cannot be activated. Mechanical electromagnetic locks, on the other hand, are installed at the grounding switch operating hole or operating handle. The latch of the electromagnetic lock extends or retracts driven by the logic judgment result: when locked, the latch extends and directly jams the grounding switch operating mechanism (such as the operating handle rotating shaft or the operating hole cover), preventing the operator from rotating the operating handle or inserting it into the operating hole, mechanically forcibly preventing the grounding switch from operating. The two interlocking mechanisms are independent of each other. Either mechanism can independently prevent the grounding switch from closing when the condition is not met. Even if the relay of the electrical interlocking node fails due to faults such as contact sticking, the mechanical electromagnetic lock can still perform its interlocking function normally. Conversely, even if the electromagnetic lock loses power due to a power failure, its fault-oriented safety design (power failure lockout) can still maintain the interlocked state, while the electrical interlocking node can still reliably disconnect the closing circuit, thus achieving true dual safety protection and significantly improving the fault tolerance and overall reliability of the interlocking system. This invention forms a complete safety control link from signal perception, logical operation to interlocking execution through the acquisition and fusion of multi-source signals, the comprehensive judgment of the "AND" logic of triple criteria, and the coordinated action of dual redundant actuators. This control link does not rely on a single point signal or a single actuator, fundamentally overcoming the inherent defects of existing five-prevention systems that rely solely on a single status signal on their own side for interlocking judgment, such as "inability to sense the energized state of the upper side" and "loss of interlocking protection upon failure of a single signal." It can effectively prevent serious accidents such as upstream substation over-level tripping and large-scale power outages caused by accidental closing of the grounding switch, and effectively ensure the safe and stable operation of the power system and the life safety of operators.

[0027] During operation, when the grounding switch operator prepares to close the circuit, the system first acquires the circuit breaker's open / close position signal from the integrated protection and control device or distribution terminal of the upstream outgoing line bay, simultaneously acquiring the current signal from the secondary side of the CT in the upstream outgoing line bay, and the voltage or energization status signal from the secondary side of the PT on the local incoming line. Then, the logic judgment unit compares these three signals with preset conditions: checking if the circuit breaker is indeed in the open position, if the current is less than or equal to 0.01A, and if there is no voltage on the local side. Only when all three conditions are true does the logic judgment unit output a closing permission signal, the electrical interlocking node in the closing circuit closes, the electromagnetic lock tongue retracts, and the grounding switch operating mechanism can operate. If any condition is not met, the logic judgment unit maintains the output interlocking signal, the closing circuit is cut off, the electromagnetic lock tongue remains locked, and the grounding switch cannot be closed. This technical solution achieves fully automated control from signal acquisition and logic judgment to interlocking execution, avoiding the possibility of human error and significantly improving the safety of grounding switch operation.

[0028] Example 2: Figure 2 As shown, this embodiment provides a grounding switch interlocking system, including: a signal acquisition unit, used to acquire the opening and closing status signal of the upstream outgoing line bay circuit breaker, the current detection signal on the line side of the upstream outgoing line bay, and the voltage detection signal or energized status signal on the incoming line side of this side; a logic judgment unit, connected to the signal acquisition unit, used to perform logical judgment based on the opening and closing status signal, the current detection signal, and the voltage detection signal or energized status signal, and output a closing permission signal if and only if the upstream outgoing line bay circuit breaker is in the open position, the current on the line side is less than or equal to a preset threshold, and there is no voltage on the incoming line side of this side; otherwise, output an interlocking signal; and an interlocking execution unit, connected to the logic judgment unit, used to prevent the grounding switch closing operation when the interlocking signal is received, and to release the restriction on the grounding switch closing operation when the closing permission signal is received. This system can be integrated into the measurement and control devices in the secondary compartment of the switchgear or configured independently in the switchgear instrument room. The input terminal of the signal acquisition unit is connected to the control cable of the upper-level bay via an aviation plug or terminal block. The logic judgment unit can be implemented using a high-performance industrial-grade microcontroller or PLC. The output terminal of the interlocking execution unit is connected to the grounding switch closing circuit and electromagnetic lock via a control cable. The triple-criteria interlocking method is implemented in the form of a hardware system. Through the collaborative work of each unit, the entire process of signal acquisition, logic operation, and interlocking execution is automatically completed without manual judgment or intervention. It also has the engineering advantages of convenient modification and simple maintenance, and can be flexibly applied to the upgrading and transformation of the five-prevention system in new stations or existing stations.

[0029] In this embodiment, the signal acquisition unit includes a current signal acquisition subunit, a voltage signal acquisition subunit, and a live status signal receiving subunit. The current signal acquisition subunit is used to acquire the secondary current value of the upstream outgoing line bay, the voltage signal acquisition subunit is used to acquire the secondary voltage value of the incoming voltage transformer on this side, and the live status signal receiving subunit is used to receive the live status signal output by the live status display device on this side. The current signal acquisition subunit can use a 4mA to 20mA analog input module or read the current measurement value of the integrated protection device via RS485. The voltage signal acquisition subunit can use a voltage transmitter or be directly connected to the PT secondary circuit, quantizing the analog voltage into a digital quantity for logic judgment through A / D conversion. The live status signal receiving subunit can use a switch input module to receive the passive or active contact signal of the live status display device. Each subunit can be flexibly selected according to the actual field configuration. When both PT and live status display devices are available on site, the two methods can serve as backups and verifications for each other.

[0030] In this embodiment, the interlocking execution unit includes an electrical interlocking subunit and a mechanical electromagnetic lock subunit. The electrical interlocking subunit is used to connect its interlocking contacts in series with the grounding switch closing circuit to cut off the closing circuit. The mechanical electromagnetic lock subunit is used to lock the grounding switch operating mechanism with its locking tongue to prevent its operation. The core component of the electrical interlocking subunit is a high-reliability intermediate relay, whose coil is driven by the interlocking signal of the logic judgment unit, and its normally open contact is connected in series with the grounding switch closing circuit. The electromagnet of the mechanical electromagnetic lock subunit is linked with the allow signal output by the logic judgment unit. When closing is allowed, the electromagnet is energized and attracted, the locking tongue retracts, and the operating handle can be rotated. The two interlocking methods are physically independent but logically work together on the same grounding switch operating object, without affecting each other's interlocking function. Even if the electrical interlocking contacts fail due to adhesion or other reasons, the mechanical electromagnetic lock can still independently perform the interlocking function, and vice versa. This dual redundancy design ensures the high reliability of the interlocking function. Even if one mechanism fails, the other can still effectively prevent misoperation, meeting the high reliability requirements of power systems for safety devices.

[0031] After the system is powered on, the signal acquisition unit continuously monitors three signals: the position of the upstream circuit breaker, the upstream line current, and the voltage / energization status of this side, and transmits the real-time data to the logic judgment unit. The logic judgment unit performs a comprehensive judgment on the three signals at a preset period (e.g., every 100 milliseconds). When the operator attempts to close the grounding switch, if all three conditions are met simultaneously, the logic judgment unit sends a closing permission command to the interlocking execution unit. The relay contacts of the electrical interlocking subunit close, the latch of the mechanical electromagnetic lock subunit retracts, and the grounding switch can operate normally. If any condition is not met, the logic judgment unit outputs an interlocking signal, the electrical interlocking contacts remain open, the mechanical electromagnetic lock remains locked, and the grounding switch cannot be operated. Through this system, substation maintenance personnel can safely and reliably complete the grounding operation of the incoming line bay, effectively avoiding the occurrence of accidents involving the energized grounding switch.

[0032] Example 3: This example provides a switchgear, including: a cabinet; a grounding switch installed inside the cabinet; and the aforementioned grounding switch interlocking system. The interlocking execution unit of the grounding switch interlocking system is connected to the operating mechanism of the grounding switch. The interlocking execution unit prevents the grounding switch from closing when the logic judgment unit outputs an interlocking signal, and allows the grounding switch to close when it outputs a closing permission signal. The cabinet can be an armored withdrawable metal-enclosed switchgear or a fixed switchgear. The cabinet contains a busbar compartment, a circuit breaker compartment, a cable compartment, and an instrument compartment. The grounding switch is installed in the cable compartment or on the outgoing side, and the operating mechanism is located on the front panel of the cabinet. The signal acquisition unit and logic judgment unit of the grounding switch interlocking system are integrated into the intelligent control module inside the instrument compartment. The electrical interlocking contact of the interlocking execution unit is connected in series with the grounding switch closing control circuit. The mechanical electromagnetic lock is installed at the operating hole of the grounding switch and is connected to the logic judgment unit through a control cable. By organically integrating the grounding switch interlocking system with the switch cabinet body, an integrated safety protection solution is formed. Users do not need to install interlocking devices separately when purchasing and using the switch cabinet, which reduces the workload of on-site installation and commissioning and improves the overall reliability and aesthetics of the equipment.

[0033] In this embodiment, the operating mechanism of the grounding switch is an operating handle or an operating shaft; the interlocking execution unit of the grounding switch interlocking system is located on the cabinet at the position corresponding to the operating mechanism; the signal input terminal of the signal acquisition unit is connected to the distribution terminal of the upstream outgoing line bay and / or the voltage monitoring terminal of the local incoming line. The operating handle is connected to the transmission mechanism of the grounding switch through the operating shaft. When the operating handle is rotated, the grounding switch is opened and closed through the operating shaft. The mechanical electromagnetic lock of the interlocking execution unit is installed on the cover of the operating handle or the locking hole of the operating shaft. When the lock tongue extends, it locks the cover so that it cannot be opened or directly blocks the rotation of the operating shaft. The signal acquisition unit is connected to the distribution terminal of the upstream outgoing line bay (to obtain circuit breaker position and current signals) and the voltage monitoring terminal of the local incoming line (to obtain voltage or live signals) through the reserved wiring terminals of the secondary terminal block of the cabinet using shielded cables. The wiring method is simple, highly standardized, and convenient for on-site construction and maintenance.

[0034] In the normal operation of the switchgear of this invention, the grounding switch interlocking system monitors in real time the position of the upstream outgoing circuit breaker, the current of the upstream line, and the voltage status of the local incoming line. When the operator needs to switch the switchgear from operation to maintenance and close the grounding switch, they must first confirm that the upstream outgoing circuit breaker is open, there is no current in the upstream line, and there is no voltage on the local incoming line. If all three conditions are met, the interlocking system is unlocked, and the operator can normally close the grounding switch. If any condition is not met, the interlocking system remains locked, and the operator cannot close the grounding switch. Through this integrated design, the switchgear itself has the safety protection capability to prevent electrolytic grounding switches, fundamentally eliminating the potential for serious misoperation accidents caused by non-standard operating procedures or imperfect five-prevention logic, effectively ensuring the personal safety of operators and the power supply reliability of the power system.

[0035] It should be noted that in this invention, "upper-level outgoing line bay" refers to the outgoing line bay in a substation or power distribution station that directly supplies power to this side from the power source, relative to the switchgear on this side. Its circuit breaker position and line current signal can be obtained through hard-contact methods (directly connected via control cable) or communication methods (obtained from the upper-level station control layer via IEC61850 or Modbus protocols). "Preset threshold" refers to the critical value set by the current judgment process to distinguish between "current present" and "current absent." This value is determined comprehensively based on the rated value of the secondary side of the current transformer and the on-site zero drift level. "Voltage transformer secondary side voltage" includes two rated values: 57.7V and 100V, corresponding to the phase voltage and line voltage output of the voltage transformer, respectively. In actual judgment, the corresponding reference value should be selected for comparison based on the on-site PT wiring method. "Live display device" refers to a capacitive or inductive high-voltage live indicator configured in the switchgear. Its output contacts are passive dry contacts or active level signals, which can be directly connected to the switch input module of the measurement and control device. "Electrically interlocked node" refers to a normally open electrically controlled node composed of relays or solid-state switches. Its on / off state is controlled by logic judgment results and is connected in series in the closing circuit to play an electrical on / off control role. "Mechanical electromagnetic lock" refers to a device that uses an electromagnet to drive the latch to extend or retract to achieve mechanical locking and unlocking. Its latch engages with the slot or lock hole of the operating mechanism to achieve locking. "Signal acquisition unit" is an intelligent acquisition module with analog and digital input functions. It can be configured to simultaneously acquire current, voltage, and digital signals, or can be selectively configured according to site requirements. "Logic judgment unit" is a microprocessor or programmable logic controller (PLC) with logic operation capabilities. It can use industrial-grade chips, has multiple input / output interfaces and communication functions, and outputs control commands in real time according to preset criteria. "Interlocking execution unit" consists of two independent mechanisms: an electrical interlocking subunit and a mechanical electromagnetic lock subunit. The two mechanisms execute the interlocking action independently. The "operating mechanism" is a manual or electric operating device for the grounding switch, including an operating handle, an operating shaft, a transmission link, and a corresponding locking mechanism. When the operating handle is rotated, it drives the moving contact of the grounding switch to contact or separate from the stationary contact through the operating shaft and the transmission link.

[0036] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for locking a grounding switch, characterized in that, Includes the following steps: Obtain the opening and closing status signal of the upstream outgoing circuit breaker; Acquire the current detection signal on the line side of the upstream outgoing interval; Acquire the voltage detection signal and / or energized status signal of the incoming line on this side; Logical judgment is made based on the opening and closing status signal, current detection signal, voltage detection signal and / or energized status signal; The grounding switch closing operation is released only if the upstream outgoing circuit breaker is in the open position, the current on the line side is less than or equal to the preset threshold, and there is no voltage on the incoming line side of this side. Otherwise, the grounding switch closing operation is kept locked.

2. The grounding bar locking method according to claim 1, characterized in that: The preset threshold is the secondary current value of 0.01A.

3. The grounding bar locking method according to claim 1, characterized in that: The specific method for determining whether there is voltage on the incoming line side is as follows: collect the secondary voltage of the incoming line voltage transformer on this side, and determine that there is no voltage when the secondary voltage value is lower than the preset voltage threshold; and / or, acquire the energized status signal output by the energized display device on this side, and determine that there is no voltage when the energized status signal is a no-voltage signal.

4. The grounding bar locking method according to claim 1, 2, or 3, characterized in that: The method for interlocking the grounding switch closing operation is as follows: the normally open node of the electrical interlocking node is connected in series with the grounding switch closing circuit; when the judgment result is an interlocking signal, the normally open node is opened to cut off the closing circuit; when the judgment result is an allow signal, the normally open node is closed to conduct the closing circuit.

5. The grounding bar locking method according to claim 1, 2, or 3, characterized in that: The method for locking the grounding switch closing operation is as follows: the locking tongue of the electromagnetic lock stops the grounding switch operating mechanism to prevent its operation. The electromagnetic lock is driven by the result of logical judgment.

6. A grounding bar interlocking system, characterized in that, include: The signal acquisition unit is used to acquire the opening and closing status signals of the upstream outgoing line bay circuit breaker, the current detection signals on the line side of the upstream outgoing line bay, and the voltage detection signals or energized status signals on the incoming line side of this side. The logic judgment unit, connected to the signal acquisition unit, is used to make logical judgments based on the opening and closing status signals, current detection signals, voltage detection signals, or energized status signals. It outputs a closing permission signal only when the upstream outgoing line interval circuit breaker is in the open position, the current on the line side is less than or equal to the preset threshold, and there is no voltage on the incoming line side of this side; otherwise, it outputs a blocking signal. The interlocking execution unit, connected to the logic judgment unit, is used to prevent the grounding switch closing operation when a interlocking signal is received, and to release the restriction on the grounding switch closing operation when a closing permission signal is received.

7. The grounding bar interlocking system according to claim 6, characterized in that: The signal acquisition unit includes a current signal acquisition subunit, a voltage signal acquisition subunit, and a live status signal receiving subunit. The current signal acquisition subunit is used to acquire the secondary current value of the upstream outgoing line bay line side, the voltage signal acquisition subunit is used to acquire the secondary voltage value of the incoming voltage transformer on this side, and the live status signal receiving subunit is used to receive the live status signal output by the live display device on this side.

8. The grounding bar interlocking system according to claim 6 or 7, characterized in that: The interlocking execution unit includes an electrical interlocking subunit and a mechanical electromagnetic interlocking subunit. The electrical interlocking subunit is used to connect its interlocking contacts into the grounding switch closing circuit to cut off the closing circuit. The mechanical electromagnetic interlocking subunit is used to stop the grounding switch operating mechanism by locking the locking tongue to prevent its operation.

9. A switch cabinet, characterized in that, include: Cabinet; Grounding switch installed inside the cabinet; And the grounding switch interlocking system as described in any one of claims 6 to 8, wherein the interlocking execution unit of the grounding switch interlocking system is connected to the operating mechanism of the grounding switch; the interlocking execution unit prevents the grounding switch from closing when the logic judgment unit outputs an interlocking signal, and allows the grounding switch to close when it outputs an allow closing signal.

10. The switchgear according to claim 9, characterized in that: The operating mechanism of the grounding switch is an operating handle or an operating shaft; the interlocking execution unit of the grounding switch interlocking system is located on the cabinet at the position corresponding to the operating mechanism; the signal input terminal of the signal acquisition unit is connected to the power distribution terminal of the upstream outgoing line bay and / or the voltage monitoring terminal of the local incoming line.

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