Three power supply incoming line PLC control power supply system

Abstract

The application discloses a three-power-line PLC control power supply system and belongs to the field of electric power automation control, which comprises a power-line monitoring module, a man-machine interaction module, a PLC control module, an actuator module, a signal output module, a safety interlocking module and a backup power supply guarantee module. The application adopts PLC as a logic control core, combines with real-time feedback of a power-line voltage monitoring relay, realizes automatic switching and logic interlocking of two mains and one oil machine through the actuator module, simultaneously constructs a mechanical and electrical triple protection system by using the safety interlocking module, and cooperates with the backup power supply guarantee module to ensure uninterrupted power supply during switching. The application can realize intelligent priority management and seamless switching of three power supplies, and significantly improves the reliability, safety and automatic scheduling level of the power supply system.

Description

Technical Field

[0001] This invention relates to the field of power automation control, and in particular to a three-power-input PLC-controlled power supply system. Background Technology

[0002] This invention relates to the field of power distribution automation control technology, specifically to a control system for automatic switching of multiple power supply inputs. This system is mainly applied in scenarios with extremely high requirements for power supply continuity, such as telecommunications equipment rooms, data centers, hospitals, and large industrial production lines. In such scenarios, it is typically necessary to configure two or more mains power inputs and equip them with diesel generator sets as backup power. An automatic switching device ensures that in the event of a main power failure, the load bus can quickly connect to the backup power supply to maintain equipment operation.

[0003] However, existing multi-power switching solutions still have significant limitations in practical applications. Traditional switching equipment mostly only supports simple logical switching between two power sources. When faced with complex three-power-source conditions such as "dual AC power + generator," they often lack robust priority automated scheduling logic, leading to strong reliance on manual operation and low switching efficiency. Furthermore, existing systems are prone to logic restarts due to control loop power loss during power switching, and the physical and mechanical interlocks and electrical logic protection between multiple circuits are not sufficiently robust, posing a safety risk of multi-power-source grid collisions. This makes it difficult to meet the stringent high reliability requirements of telecom-grade cabinets. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a three-power-input PLC-controlled power supply system. It employs a PLC controller as the core logic processing unit, coupled with a high-precision voltage monitoring relay group and an electrically operated circuit breaker, to construct a triple protection system integrating mechanical interlocking, electrical circuit interlocking, and PLC logic interlocking. Furthermore, a UPS redundancy switching mechanism is introduced to ensure the stability of the control circuit.

[0005] The above objectives can be achieved through the following approach: A three-power-input PLC-controlled power supply system includes: an input monitoring module, used to collect phase voltage signals of mains power line 1, mains power line 2, and generator power line in real time through input voltage monitoring relays, and send status signals reflecting normal or fault voltage to the PLC controller; a human-machine interface module, used to allow users to select the system's operating mode and power priority, wherein the operating mode includes manual mode and automatic mode, and the priority includes mains power line 1 priority or mains power line 2 priority; a PLC control module, used to receive signals from the input monitoring module and the human-machine interface module, and send control commands to the corresponding actuators according to a preset logic program to realize the automatic switching logic of the three power supplies; and an actuator module, including a first circuit breaker, a second circuit breaker, and a third circuit breaker respectively installed on the three input lines. The system includes three circuit breakers, each equipped with an electric operating mechanism to receive commands from the PLC control module and perform closing or opening actions; a signal output module to send a remote start signal to an external generator when the PLC control module determines that both mains power 1 and mains power 2 are in a fault state, thereby controlling the generator to start supplying power; a safety interlock module, including a mechanical interlock mechanism between the first and second circuit breakers, and an electrical interlock circuit consisting of the PLC controller output and the auxiliary contacts of each circuit breaker, to ensure that only one incoming circuit breaker is in a closed state at any given time; and a backup power supply module, including a UPS power switching relay, to provide continuous control power to the PLC control module and the actuator module during system switching, ensuring that the control logic is not interrupted.

[0006] Optionally, the incoming line monitoring module includes: a first monitoring unit comprising two first voltage monitoring relays, respectively used to monitor the A-phase and C-phase voltages of the mains power 1 incoming line; a second monitoring unit comprising two second voltage monitoring relays, respectively used to monitor the A-phase and C-phase voltages of the mains power 2 incoming line; and a third monitoring unit comprising two third voltage monitoring relays, respectively used to monitor the A-phase and C-phase voltages of the generator incoming line; wherein, the auxiliary contacts of the first voltage monitoring relays, the second voltage monitoring relays, and the third voltage monitoring relays are respectively connected to the input terminals of the PLC control module, converting the undervoltage signal or normal signal of each power supply into a switching signal for uploading.

[0007] Optionally, the human-machine interaction module includes: a mode switching unit, comprising a manual / automatic switch mounted on the system cabinet panel for switching between manual control mode and automatic switching mode; a priority configuration unit, comprising a main / standby selection switch mounted on the panel for presetting mains power 1 or mains power 2 as the first priority power supply of the system; and a status indication unit, comprising power indicator lights corresponding to the three incoming lines, and closing / opening indicator lights corresponding to the first, second, and third circuit breakers, for real-time display of the energized status of each power supply and the operating position of the circuit breakers; wherein the switching signals of the mode switching unit and the priority configuration unit are connected to the signal input terminal of the PLC control module as the basis for determining whether the logic program executes automatic switching or manual blocking.

[0008] Optionally, the PLC control module includes: a logic processing unit, which is the PLC controller host, used to store and run control programs including mains power transfer logic, generator self-start logic, and fault interlocking logic; a signal input interface, used to connect the incoming line monitoring module, the human-machine interface module, and the auxiliary contacts of each circuit breaker to obtain real-time feedback on power status, operating mode, and circuit breaker position; and an instruction output interface, which connects to the coils of several intermediate relays through output terminals, wherein the contacts of the intermediate relays are connected in series in the electric operating circuit of the actuator module; wherein, in automatic mode, the logic processing unit controls the corresponding intermediate relay to operate according to the voltage status collected by the signal input interface through the instruction output interface, so as to drive the electric operating mechanism of the first, second, or third circuit breaker to complete the closing or opening operation.

[0009] Optionally, the actuator module includes: a circuit breaker main unit comprising three AC molded case circuit breakers, serving as the first, second, and third circuit breakers respectively, all three circuit breakers employing a stacked installation structure; an electric operating unit comprising an electric operating mechanism installed on each of the circuit breakers, the control power input terminal of the electric operating mechanism being connected to the instruction output interface of the PLC control module; and a position feedback unit comprising auxiliary contacts and alarm contacts installed inside each of the circuit breakers, the auxiliary contacts being used to provide feedback to the PLC control module on the real-time closing and opening status of the circuit breaker, and the alarm contacts being used to provide feedback to the PLC control module on the fault trip signal of the circuit breaker; wherein the first, second, and third circuit breakers are connected in parallel via a shared horizontal busbar, and the PLC control module controls the electric operating unit to achieve logical switching of the three incoming power supplies to the load busbar.

[0010] Optionally, the signal output module includes: a logic judgment unit, used to determine in real time whether the first incoming power supply and the second incoming power supply are simultaneously in a fault state; a start execution unit, including a start relay controlled by the PLC control module, whose normally open contact serves as a remote start signal contact, used to close when the start conditions are met to connect the start circuit of the external generator; and a stop control unit, used to disconnect the output signal of the start relay and shut down the external generator after the PLC control module determines that either mains power input voltage has returned to normal; wherein, the output contact of the start execution unit is a passive dry contact, which extends to the generator room through an external control cable to realize remote automated scheduling of the generator power supply system.

[0011] Optionally, the safety interlock module includes: a mechanical interlock unit comprising a horizontal mechanical interlock frame installed between the first circuit breaker and the second circuit breaker, and a rear plate mechanical interlock mechanism installed behind the circuit breaker, used to restrict the simultaneous closing of the first circuit breaker and the second circuit breaker by physical linkage; an electrical logic interlock unit integrated into the control program of the PLC control module, used to detect the auxiliary contact signals of the other two circuit breakers before executing the closing command of any circuit breaker, and only output the closing drive signal when the other two circuit breakers are both in the open position; and a hardware circuit interlock unit comprising normally closed auxiliary contacts of other circuit breakers connected in series in the electric operation closing circuit of each circuit breaker, realizing the closing logic blocking between the three circuit breakers through hardware wiring; wherein, the mechanical interlock unit, the electrical logic interlock unit, and the hardware circuit interlock unit together construct a triple interlock system to ensure that the mains power line 1, mains power line 2, and generator line do not collide under any operating conditions.

[0012] Optionally, the backup power supply module includes: a power access unit comprising several UPS incoming power circuit breakers for connecting an external UPS uninterruptible power supply and using it as a backup power supply for the system's control circuit; an automatic switching execution unit comprising two sets of UPS power supply switching relays with mechanical interlocking mechanisms for automatically switching between the system's main control power supply and the backup control power supply, wherein the mechanical interlocking mechanism is used to prevent physical collision between the two types of power supplies; and a control power distribution circuit for distributing the stable power output from the automatic switching execution unit to the PLC control module, the incoming line monitoring module, and the relay coil; wherein, during the power supply gap generated by the automatic switching of the first circuit breaker, the second circuit breaker, or the third circuit breaker, the automatic switching execution unit quickly connects the UPS power supply path to ensure that the operating logic of the PLC control module is not interrupted or reset due to a momentary voltage drop.

[0013] Compared with the prior art, the present invention has the following advantages: 1. Achieved highly automated three-power supply logic management and priority switching. This invention overcomes the logic dead zone problem of traditional equipment under multi-power supply conditions by cooperating with a PLC controller and an incoming line voltage monitoring relay. It can automatically identify faults, automatically start and stop generators, and automatically switch back after mains power is restored, based on preset priorities for mains power 1, mains power 2, and generators, greatly reducing manual intervention and improving the real-time performance of power supply scheduling.

[0014] 2. A triple safety interlocking mechanism combining mechanical and electrical elements has been constructed, ensuring extremely high safety. By setting up a physical mechanical interlocking framework between the first and second circuit breakers, combined with PLC software logic interlocking and hardware electrical interlocking in the secondary circuits, a three-in-one protection system is formed. This design completely eliminates the technical risks of grid collisions or arcing short circuits between the three incoming power supplies, ensuring safe operation under high-voltage and high-current environments.

[0015] 3. It possesses excellent control power stability, ensuring uninterrupted logic during switching. A backup power protection module supported by a UPS (Uninterruptible Power Supply) is introduced, along with a dedicated switching relay. During the momentary power outage caused by the switching between main and backup power supplies, the control loop can seamlessly switch to UPS power, effectively preventing PLC shutdowns or program resets due to voltage fluctuations, and enhancing the power supply continuity of telecommunications-grade critical equipment.

[0016] 4. High hardware integration facilitates future maintenance and expansion. The use of a stacked circuit breaker structure and modular control circuit design not only saves physical space within the cabinet but also makes the connection between the system's status feedback and the PLC control terminal clearer. This design reduces the difficulty of troubleshooting the system and also reserves standardized interfaces for future integration with remote centralized control systems.

[0017] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a three-power-input PLC-controlled power supply system according to an embodiment of the present invention.

[0020] Figure 2 This is a screen-to-screen logical topology diagram according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of a system according to an embodiment of the present invention.

[0022] Figure 4 This is a reference diagram of component symbols in an embodiment of the present invention.

[0023] Figure 5 This is a power monitoring and control power circuit diagram according to an embodiment of the present invention.

[0024] Figure 6 This is a PLC input / output interface allocation diagram according to an embodiment of the present invention.

[0025] Figure 7 This is a mapping diagram of the external cable connection terminal block according to an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Reference Figure 1 One embodiment of the present invention proposes a three-power-input PLC-controlled power supply system, which uses a PLC controller as the core logic processing unit, and is equipped with a high-precision voltage monitoring relay group and an electrically operated circuit breaker to construct a triple protection system integrating mechanical interlocking, electrical circuit interlocking and PLC logic interlocking, and introduces a UPS redundancy switching mechanism to ensure the stability of the control circuit.

[0028] The system described in this embodiment specifically includes: The incoming line monitoring module is used to collect the phase voltage signals of the mains power line 1, mains power line 2 and generator power line in real time through the incoming line voltage monitoring relay, and send the status signal reflecting the voltage normal or fault to the PLC controller. The human-computer interaction module is used to allow users to select the system's working mode and power priority. The working mode includes manual mode and automatic mode, and the priority includes mains power 1 priority or mains power 2 priority. The PLC control module is used to receive signals from the incoming line monitoring module and the human-machine interaction module, and send control commands to the corresponding actuators according to the preset logic program to realize the automatic switching logic of the three power supplies. The actuator module includes a first circuit breaker, a second circuit breaker, and a third circuit breaker respectively installed on the three incoming lines. Each circuit breaker is equipped with an electric operating mechanism for receiving instructions from the PLC control module to perform closing or opening actions. The signal output module is used to send a remote start signal to an external generator to control the generator to start supplying power when the PLC control module determines that both mains power 1 and mains power 2 are in a fault state. The safety interlock module includes a mechanical interlocking mechanism installed between the first circuit breaker and the second circuit breaker, and an electrical interlocking circuit consisting of the output terminal of the PLC controller and the auxiliary contacts of each circuit breaker, to ensure that only one incoming circuit breaker is in the closed state at any time. The backup power supply module includes a UPS power switching relay, which is used to provide continuous control power to the PLC control module and actuator module during system switching to ensure that the control logic is not interrupted.

[0029] Specifically, the incoming line monitoring module utilizes six CAD3207C incoming line voltage monitoring relays (KJ1 to KJ6) to collect status data. (Reference) Figure 2The mains power line 1 is connected to KJ1 and KJ2 via a sampling circuit, the mains power line 2 is connected to KJ3 and KJ4, and the generator power line is connected to KJ5 and KJ6. When any of the incoming power lines experiences a phase voltage undervoltage or loss-of-voltage fault, the monitoring relay contacts release, transmitting a switch signal reflecting the power abnormality to the PLC control module via terminal block X1. The PLC controller scans the input interface status in real time, completing the logical extraction of the power quality of the three incoming power lines. The human-machine interface module establishes the operating benchmark through the SA1 manual / automatic transfer switch and the SA2 master / slave selection switch installed on the cabinet panel. The PLC control module reads the physical signals from input points I0.0 to I0.2. If the SA2 master / slave selection switch is set to the mains power 1 priority position, the PLC controller's internal program locks mains power 1 as the first priority power supply. When the incoming power monitoring module reports that the mains power 1 voltage has returned to normal, regardless of the current power supply status, the PLC control module will trigger the priority switchback program to ensure that the power supply automatically flows to the higher priority circuit. The actuator module receives closing and opening commands from the PLC control module. To implement the three-power supply inter-transfer logic, the PLC controller command output interface first drives intermediate relays 1KA1 to 3KA2. After the normally open contacts of the intermediate relays close, the MOE electric operating mechanism circuit for the T6S630 circuit breaker is connected. Before executing any closing command, the PLC control module must obtain the opening confirmation signals of the auxiliary contacts of the other two circuit breakers through the position feedback unit. Only after confirming that the non-target circuit breaker is physically open can the electric operating mechanism be energized to drive the main contacts to close. When the signal output module determines that both mains power 1 and mains power 2 are in a fault state and the operating mode is automatic, it jumps to the generator starting branch. The PLC control module drives the starting relay to actuate, sending a passive dry contact start signal to the external generator. When the incoming line monitoring module reports that the generator voltage is stable and detects the generator start-ready signal, the PLC control module drives the third circuit breaker to close. When the voltage of either mains power supply 1 or mains power supply 2 returns to normal, the signal output module automatically disconnects the generator operating signal according to the PLC command, realizing intelligent switching of energy supply. The backup power protection module performs power redundancy protection through switching relays KP1 to KP3 of model LC1D12M7C. During the momentary power outage caused by circuit breaker switching, the switching relays quickly connect the UPS output power circuit introduced by circuit breakers 1CB to 4CB using a mechanical interlocking structure. This process ensures that the PLC control module, intermediate relay coils, and position feedback unit receive continuous power supply during power outages, preventing logic judgment resets due to momentary voltage drops, and ensuring the continuity of the entire three-power switching process.

[0030] Optionally, the incoming line monitoring module includes: The first monitoring unit includes two first voltage monitoring relays, which are used to monitor the voltage of phase A and phase C of the mains power line 1, respectively. The second monitoring unit includes two second voltage monitoring relays, which are used to monitor the voltage of phase A and phase C of the mains power line 2, respectively. The third monitoring unit contains two third voltage monitoring relays, which are used to monitor the A-phase and C-phase voltages of the generator inlet line, respectively. The auxiliary contacts of the first voltage monitoring relay, the second voltage monitoring relay, and the third voltage monitoring relay are respectively connected to the input terminals of the PLC control module to convert the undervoltage signal or normal signal of each power supply into a switch signal for uploading.

[0031] Specifically, the incoming line monitoring module uses a unit-based monitoring method to analyze the voltage quality of the three power supplies. The first monitoring unit uses two voltage monitoring relays, KJ1 and KJ2 (model CAD3207C), to collect the incoming voltage of mains power line 1. (Reference) Figure 2 Relay KJ1 and relay KJ2 are connected to phases A and C of the mains power input line 1. This two-phase sampling method, covering the three-phase status, allows the first monitoring unit to accurately determine whether the mains power input line 1 has experienced voltage loss, phase failure, or severe undervoltage. The second monitoring unit uses voltage monitoring relays KJ3 and KJ4 to monitor the voltage of phases A and C of the mains power input line 2. The third monitoring unit uses voltage monitoring relays KJ5 and KJ6 to monitor the voltage of phases A and C of the generator input line. (Reference) Figure 2 The wiring circuits and each sampling circuit are equipped with FU series fuses for short-circuit protection. When any monitoring unit determines that the incoming power supply voltage is lower than a preset safety threshold, the internal coil of the corresponding monitoring relay is de-energized, causing its normally open contact to release and change from a closed state to an open state. The auxiliary contacts of the voltage monitoring relays in each monitoring unit are led out through wire numbers 1001, 1003, 2001, 2003, 3001, and 3003, respectively. (Reference) Figure 3 The PLC allocation table shows that these physical contacts are connected to the input terminals I0.3 to I1.0 of the PLC control module. Through this connection, the power supply status on the high-voltage side is converted into a DC 24V switching logic signal recognizable by the PLC controller. The PLC controller cyclically scans the level changes of these input terminals to obtain the fault status of each incoming power line in real time, providing basic data support for the logic jumps of subsequent automatic switching programs.

[0032] Optionally, the human-computer interaction module includes: The mode switching unit includes a manual / automatic switch located on the system cabinet panel, used to switch between manual control mode and automatic switching mode; The priority configuration unit includes a main / standby selection switch on the panel, which is used to preset either mains power 1 or mains power 2 as the first priority power supply of the system. The status indication unit includes power indicator lights corresponding to the three incoming lines, and closing / opening signal lights corresponding to the first, second, and third circuit breakers, for real-time display of the energized status of each power source and the operating position of the circuit breaker. The switching signals of the mode switching unit and the priority configuration unit are connected to the signal input terminal of the PLC control module, serving as the basis for determining whether the logic program should automatically switch on or manually block.

[0033] Specifically, the human-machine interface module establishes its operational logic through hardware switches mounted on the cabinet panel. The mode switching unit uses an SA1 manual / automatic selector switch to physically switch between manual control loops and PLC automatic switching programs. The priority configuration unit uses an SA2 master / slave selector switch to preset either mains power line 1 or mains power line 2 as the preferred power supply loop. (Reference) Figure 3 The physical states of SA1 and SA2 are converted to high and low levels through contact closure, respectively connected to the input terminals I0.0, I0.1, and I0.2 of the PLC control module, serving as prerequisites for determining the priority of the control program execution. The status indication unit utilizes an array of indicator lights mounted on the cabinet panel for real-time monitoring. (Reference) Figure 4 and Figure 5 The status indicator unit includes power indicator lights connected to mains power 1, mains power 2, and the generator input line, respectively, to display the energized status of each input line. Simultaneously, the status indicator unit reads the auxiliary contact signals of each circuit breaker, driving the closing indicator lights RQD1 to RQD3 and the opening indicator lights GQD1 to GQD3 to illuminate. This design ensures that operators can determine the connection status of the three power supplies and the physical location of the actuators simply by observing the panel light status, achieving two-way human-machine interaction.

[0034] Optionally, the PLC control module includes: The logic processing unit, which is the main unit of the PLC controller, is used to store and run control programs that include mains power switching logic, generator self-starting logic, and fault interlocking logic. The signal input interface is used to connect the incoming line monitoring module, the human-machine interaction module, and the auxiliary contacts of each circuit breaker to obtain real-time feedback on power status, operating mode, and circuit breaker position. The instruction output interface connects to the coils of several intermediate relays via output terminals, and the contacts of the intermediate relays are connected in series in the electric operation circuit of the actuator module. In automatic mode, the logic processing unit controls the corresponding intermediate relay to operate based on the voltage status collected by the signal input interface, thereby driving the electric operating mechanism of the first, second, or third circuit breaker to complete the closing or opening operation.

[0035] Specifically, the PLC control module uses a Siemens S7-200 SMART series mainframe as the logic processing unit. (Reference) Figure 3 The PLC control module receives signals from the incoming line monitoring module, the human-machine interface module, and the circuit breaker auxiliary contacts via input interfaces. Input points I0.3 to I1.0 receive normal voltage signals, while I1.1 to I2.0 receive closing / opening position feedback signals from the first circuit breaker QF1, the second circuit breaker QF2, and the third circuit breaker QF3. The logic processing unit executes the programmed three-power supply switching algorithm based on changes in these input levels. The instruction output interface connects to the KA series intermediate relays via the PLC output terminals. (Reference) Figure 2 The PLC output terminals Q0.0 to Q0.5 are connected to the coils of intermediate relays 1KA1 to 3KA2, respectively. In automatic mode, after the logic processing unit determines that the switching conditions are met, it closes the corresponding output point, driving the intermediate relays to operate. The physical contacts of the intermediate relays are connected in series in the electric operating circuit of the actuator module. By controlling the energization or de-energization of the electric operating mechanism, the circuit breaker is ultimately driven to complete the physical action of closing or opening, achieving reliable isolation and control of strong and weak currents.

[0036] Optionally, the actuator module includes: The main unit of the circuit breaker includes three AC molded case circuit breakers, which serve as the first circuit breaker, the second circuit breaker and the third circuit breaker respectively, and all three circuit breakers adopt a stacked installation structure. An electric operating unit includes an electric operating mechanism installed on each of the circuit breakers, wherein the control power input terminal of the electric operating mechanism is connected to the instruction output interface of the PLC control module. The position feedback unit includes auxiliary contacts and alarm contacts installed inside each of the circuit breakers. The auxiliary contacts are used to provide feedback on the real-time closing and opening status of the circuit breaker to the PLC control module, and the alarm contacts are used to provide feedback on the fault trip signal of the circuit breaker to the PLC control module. The first, second, and third circuit breakers are connected in parallel via a shared horizontal busbar, and the PLC control module controls the electric operating unit to achieve logical switching of the three incoming power supplies to the load busbar.

[0037] Specifically, the actuator module uses three T6S630 AC molded case circuit breakers as the core components for power switching, corresponding to the first circuit breaker QF1, the second circuit breaker QF2, and the third circuit breaker QF3, respectively. (Reference) Figure 6All three circuit breakers employ a stacked mounting structure. This structure integrates the three circuit switches within the cabinet using vertically distributed mounting brackets, effectively saving space. The load terminals of the three circuit breakers are connected in parallel via a TMY-40 x 10 horizontal busbar, ultimately outputting to the load busbar. Each circuit breaker integrates high-performance automation accessories. The electric operating unit uses an MOE electric operating mechanism, whose control terminal is connected to the PLC control module. When the MOE electric operating mechanism receives a closing or opening pulse, the internal motor drives the circuit breaker mechanism to complete the main contact action. Simultaneously, the position feedback unit uses three sets of auxiliary contacts installed inside the circuit breaker to monitor the contact position in real time and connects the signal lines to the input terminal of the PLC control module. In addition, the alarm contact 1SY is used to capture the fault tripping status of the circuit breaker. Through this accessory configuration, the PLC controller can sense the physical displacement of the actuator within milliseconds, ensuring closed-loop control of the three power supply switching logic.

[0038] Optionally, the signal output module includes: The logic judgment unit is used to determine in real time whether the first incoming power supply and the second incoming power supply are both in a fault state. The start-up execution unit includes a start-up relay controlled by the PLC control module. Its normally open contact serves as a remote start-up signal contact, which is used to close when the start-up conditions are met to connect the start-up circuit of the external generator. The stop control unit is used to disconnect the output signal of the start relay and shut down the external generator after the PLC control module determines that any mains power input voltage has returned to normal. The output contact of the start-up execution unit is a passive dry contact, which extends to the generator room through an external control cable to realize remote automated scheduling of the generator power supply system.

[0039] Specifically, the signal output module achieves energy conversion and scheduling through the logic judgment unit operating within the PLC control module. (Reference) Figure 7 When the PLC control module determines, through the incoming line monitoring module, that both mains power line 1 and mains power line 2 are simultaneously experiencing a power outage or phase voltage fault, the logic program immediately triggers the generator starting branch. The PLC control module drives the start execution unit to operate through the output interface. This unit includes an intermediate relay (model CAD3207C). ​​Energizing the relay coil closes the normally open contacts, outputting a set of passive dry contact start signals to the external generator, thereby guiding the generator into the standby start-up process. During generator power supply, the stop control unit is driven in real-time by the PLC control module. (Reference) Figure 2 as well as Figure 3The system defines a shutdown point. Once the incoming power monitoring module detects that the voltage of either incoming mains line 1 or incoming mains line 2 has returned to normal, the logic judgment unit will issue a shutdown command. The PLC control module immediately cuts off the relay output power of the start-up execution unit, resetting the normally open contacts and shutting down the external generator. The entire signal transmission process is connected to the generator room via a control cable, ensuring automated switching and scheduling of power supply from the generator to the mains circuit.

[0040] Optionally, the safety interlock module includes: The mechanical interlocking unit includes a horizontal mechanical interlocking frame installed between the first circuit breaker and the second circuit breaker, and a rear plate mechanical interlocking mechanism installed behind the circuit breaker, which is used to restrict the first circuit breaker and the second circuit breaker from closing simultaneously through physical linkages. The electrical logic interlock unit is integrated into the control program of the PLC control module. Before executing the closing command of any circuit breaker, it first detects the auxiliary contact signals of the other two circuit breakers. Only when the other two circuit breakers are in the open position can the closing drive signal be output. The hardware circuit interlocking unit includes normally closed auxiliary contacts of other circuit breakers connected in series in the electric operation closing circuit of each circuit breaker, and realizes the closing logic blocking between the three circuit breakers through hardware wiring. The mechanical interlocking unit, electrical logic interlocking unit, and hardware circuit interlocking unit together form a triple interlocking system to ensure that the mains power line 1, mains power line 2, and generator power line do not collide under any operating conditions.

[0041] Specifically, the mechanical interlocking unit ensures power supply safety through physical limitations at the hardware level. A horizontal mechanical interlocking frame (model MIR-HB) is installed between the first and second circuit breakers, in conjunction with a Type F-MIR-P rear-plate mechanical interlocking mechanism installed behind the circuit breakers. This dual mechanical device uses an internal metal linkage mechanism to create physical displacement limitations. When one circuit breaker is in the closed position, the interlocking mechanism will forcibly lock the closing operation mechanism of the other circuit breaker, completely eliminating the possibility of grid connection collision between the two mains power supplies at the physical level. The electrical logic interlocking unit and the hardware circuit interlocking unit together constitute an electrical safety barrier. (Reference) Figure 7The PLC control module's internal program performs logic verification by real-time reading of the auxiliary contact signals of the first, second, and third circuit breakers transmitted by the position feedback unit. Before outputting any closing pulse, the PLC controller must confirm that the other two circuits have returned an open state. Simultaneously, in the secondary circuit wiring, the closing circuit of each circuit breaker's electric operating mechanism is connected in series with the normally closed auxiliary contacts of the other two circuit breakers. Through this interlocking system where software logic and hardware circuits support each other, a safe closed-loop control for the entire three-power supply switching process is achieved.

[0042] Optionally, the backup power supply module includes: The power access unit contains several UPS input power circuit breakers, which are used to connect to an external UPS uninterruptible power supply and use it as a backup power supply for the system's control loop. The automatic switching execution unit includes two sets of UPS power supply switching relays with mechanical interlocking mechanisms, which are used to automatically switch between the main control power supply and the backup control power supply of the system, and the mechanical interlocking mechanism is used to prevent physical collision between the two types of power supplies. A control power distribution circuit is used to distribute the stable power output from the automatic switching execution unit to the PLC control module, the incoming line monitoring module, and the relay coil. During the power supply gap caused by the automatic switching of the first circuit breaker, the second circuit breaker, or the third circuit breaker, the automatic switching execution unit quickly connects the UPS power supply path to ensure that the operating logic of the PLC control module is not interrupted or reset due to the instantaneous voltage drop.

[0043] Specifically, the backup power supply module draws on an external uninterruptible power supply (UPS) through a power access unit. (Reference) Figure 2 The external UPS power supply enters the control circuit through a miniature circuit breaker group consisting of 1CB to 4CB. The automatic switching execution unit contains two sets of LC1D12M7C type relays KP1 to KP3 with mechanical interlocking mechanisms. This unit automatically switches between the system main control power supplied by the incoming bus and the UPS backup control power supply through the relay contact logic. The mechanical interlocking structure ensures absolute physical isolation between the two types of power supplies, preventing grid connection failures between control power supplies from different sources. The control power distribution circuit is responsible for delivering the stable power supply after switching to the PLC controller and relays at all levels. When the first, second, or third circuit breaker performs an automatic switching action, the main power bus will experience a millisecond-level power outage gap. At this time, the automatic switching execution unit quickly connects the UPS power supply path by utilizing the physical characteristics of the switching relays. This process ensures that the PLC control module and its associated execution circuit receive continuous power at the moment of power switching, eliminating the risk of logic program reset or PLC host restart caused by instantaneous voltage drops, and maintaining the integrity and continuity of the three-power switching process.

[0044] It should be noted that the electrical connections between the various units described above do not necessarily represent direct or indirect connections. Any indirect connection method can be applied to the embodiments of the present invention as long as it achieves the purpose of the present invention. The above descriptions are merely exemplary embodiments of the present invention and should not be construed as limiting the scope of the present invention.

[0045] All equivalent changes and modifications made in accordance with the teachings of this invention are still within the scope of this invention. Those skilled in the art will readily conceive of other embodiments of this invention upon considering the specification and the disclosure of practical truth. This application is intended to cover any variations, uses, or adaptations of this invention that follow the general principles of this invention and include common knowledge or conventional techniques in the art not described herein.

Claims

1. A three-power-input PLC-controlled power supply system, characterized in that, The system includes: The incoming line monitoring module is used to collect the phase voltage signals of the mains power line 1, mains power line 2 and generator power line in real time through the incoming line voltage monitoring relay, and send the status signal reflecting the voltage normal or fault to the PLC controller. The human-computer interaction module is used to allow users to select the system's working mode and power priority. The working mode includes manual mode and automatic mode, and the priority includes mains power 1 priority or mains power 2 priority. The PLC control module is used to receive signals from the incoming line monitoring module and the human-machine interaction module, and send control commands to the corresponding actuators according to the preset logic program to realize the automatic switching logic of the three power supplies. The actuator module includes a first circuit breaker, a second circuit breaker, and a third circuit breaker respectively installed on the three incoming lines. Each circuit breaker is equipped with an electric operating mechanism for receiving instructions from the PLC control module to perform closing or opening actions. The signal output module is used to send a remote start signal to an external generator to control the generator to start supplying power when the PLC control module determines that both mains power 1 and mains power 2 are in a fault state. The safety interlock module includes a mechanical interlocking mechanism installed between the first circuit breaker and the second circuit breaker, and an electrical interlocking circuit consisting of the output terminal of the PLC controller and the auxiliary contacts of each circuit breaker, to ensure that only one incoming circuit breaker is in the closed state at any time. The backup power supply module includes a UPS power switching relay, which is used to provide continuous control power to the PLC control module and actuator module during system switching to ensure that the control logic is not interrupted.

2. The three-power-input PLC control power supply system according to claim 1, characterized in that, The incoming line monitoring module includes: The first monitoring unit includes two first voltage monitoring relays, which are used to monitor the voltage of phase A and phase C of the mains power line 1, respectively. The second monitoring unit includes two second voltage monitoring relays, which are used to monitor the voltage of phase A and phase C of the mains power line 2, respectively. The third monitoring unit contains two third voltage monitoring relays, which are used to monitor the A-phase and C-phase voltages of the generator inlet line, respectively. The auxiliary contacts of the first voltage monitoring relay, the second voltage monitoring relay, and the third voltage monitoring relay are respectively connected to the input terminals of the PLC control module to convert the undervoltage signal or normal signal of each power supply into a switch signal for uploading.

3. The three-power-input PLC control power supply system according to claim 1, characterized in that, The human-computer interaction module includes: The mode switching unit includes a manual / automatic switch located on the system cabinet panel, used to switch between manual control mode and automatic switching mode; The priority configuration unit includes a main / standby selection switch on the panel, which is used to preset either mains power 1 or mains power 2 as the first priority power supply of the system. The status indication unit includes power indicator lights corresponding to the three incoming lines, and closing / opening signal lights corresponding to the first, second, and third circuit breakers, for real-time display of the energized status of each power source and the operating position of the circuit breaker. The switching signals of the mode switching unit and the priority configuration unit are connected to the signal input terminal of the PLC control module, serving as the basis for determining whether the logic program should automatically switch on or manually block.

4. The three-power-input PLC control power supply system according to claim 1, characterized in that, The PLC control module includes: The logic processing unit, which is the main unit of the PLC controller, is used to store and run control programs that include mains power switching logic, generator self-starting logic, and fault interlocking logic. The signal input interface is used to connect the incoming line monitoring module, the human-machine interaction module, and the auxiliary contacts of each circuit breaker to obtain real-time feedback on power status, operating mode, and circuit breaker position. The instruction output interface connects to the coils of several intermediate relays via output terminals, and the contacts of the intermediate relays are connected in series in the electric operation circuit of the actuator module. In automatic mode, the logic processing unit controls the corresponding intermediate relay to operate based on the voltage status collected by the signal input interface, thereby driving the electric operating mechanism of the first, second, or third circuit breaker to complete the closing or opening operation.

5. The three-power-input PLC control power supply system according to claim 1, characterized in that, The actuator module includes: The main unit of the circuit breaker includes three AC molded case circuit breakers, which serve as the first circuit breaker, the second circuit breaker and the third circuit breaker respectively, and all three circuit breakers adopt a stacked installation structure. An electric operating unit includes an electric operating mechanism installed on each of the circuit breakers, wherein the control power input terminal of the electric operating mechanism is connected to the instruction output interface of the PLC control module. The position feedback unit includes auxiliary contacts and alarm contacts installed inside each of the circuit breakers. The auxiliary contacts are used to provide feedback on the real-time closing and opening status of the circuit breaker to the PLC control module, and the alarm contacts are used to provide feedback on the fault trip signal of the circuit breaker to the PLC control module. The first, second, and third circuit breakers are connected in parallel via a shared horizontal busbar, and the PLC control module controls the electric operating unit to achieve logical switching of the three incoming power supplies to the load busbar.

6. The three-power-input PLC control power supply system according to claim 1, characterized in that, The signal output module includes: The logic judgment unit is used to determine in real time whether the first incoming power supply and the second incoming power supply are both in a fault state. The start-up execution unit includes a start-up relay controlled by the PLC control module. Its normally open contact serves as a remote start-up signal contact, which is used to close when the start-up conditions are met to connect the start-up circuit of the external generator. The stop control unit is used to disconnect the output signal of the start relay and shut down the external generator after the PLC control module determines that any mains power input voltage has returned to normal. The output contact of the start-up execution unit is a passive dry contact, which extends to the generator room through an external control cable to realize remote automated scheduling of the generator power supply system.

7. The three-power-input PLC control power supply system according to claim 1, characterized in that, The safety interlock module includes: The mechanical interlocking unit includes a horizontal mechanical interlocking frame installed between the first circuit breaker and the second circuit breaker, and a rear plate mechanical interlocking mechanism installed behind the circuit breaker, which is used to restrict the first circuit breaker and the second circuit breaker from closing simultaneously through physical linkages. The electrical logic interlock unit is integrated into the control program of the PLC control module. Before executing the closing command of any circuit breaker, it first detects the auxiliary contact signals of the other two circuit breakers. Only when the other two circuit breakers are in the open position can the closing drive signal be output. The hardware circuit interlocking unit includes normally closed auxiliary contacts of other circuit breakers connected in series in the electric operation closing circuit of each circuit breaker, and realizes the closing logic blocking between the three circuit breakers through hardware wiring. The mechanical interlocking unit, electrical logic interlocking unit, and hardware circuit interlocking unit together form a triple interlocking system to ensure that the mains power line 1, mains power line 2, and generator power line do not collide under any operating conditions.

8. The three-power-input PLC control power supply system according to claim 1, characterized in that, The backup power supply module includes: The power access unit contains several UPS input power circuit breakers, which are used to connect to an external UPS uninterruptible power supply and use it as a backup power supply for the system's control loop. The automatic switching execution unit includes two sets of UPS power supply switching relays with mechanical interlocking mechanisms, which are used to automatically switch between the main control power supply and the backup control power supply of the system, and the mechanical interlocking mechanism is used to prevent physical collision between the two types of power supplies. A control power distribution circuit is used to distribute the stable power output from the automatic switching execution unit to the PLC control module, the incoming line monitoring module, and the relay coil. During the power supply gap caused by the automatic switching of the first circuit breaker, the second circuit breaker, or the third circuit breaker, the automatic switching execution unit quickly connects the UPS power supply path to ensure that the operating logic of the PLC control module is not interrupted or reset due to the instantaneous voltage drop.

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