Voltage zero-crossing monitoring protection device for reactive switching switch

Abstract

The invention belongs to the technical field of power transformation equipment, and particularly relates to a reactive switching switch voltage zero-crossing monitoring protection device which comprises a monitoring module and a protection module. The outer sides of the monitoring module and the protection module are respectively provided with a housing, and the two housings are installed together. The monitoring module comprises a controller, a semiconductor switch, a relay, a contactor, a zero-cross detection module and a communication module. The protection module comprises a heat dissipation assembly and a protection module control mainboard. An early warning unit and a fault diagnosis unit are arranged in the protection module control mainboard. The protection module is installed on the side close to the heat dissipation assembly. According to the scheme, the semiconductor switch is matched with the zero-crossing detection module, conduction at a voltage zero-crossing point and disconnection at a current zero-crossing point can be realized, the inrush current suppression ratio is improved, impact on a power grid during switching is avoided, and the service life of a capacitor and a switch contact is prolonged. The zero-crossing detection module and the linear prediction model eliminate harmonic interference in advance and pre-judge a zero-crossing point, response delay is reduced, and the problem of traditional detection lag is solved.

Description

Technical Field

[0001] This invention relates to the field of power equipment technology, specifically to a reactive power switching switch voltage zero-crossing monitoring and protection device. Background Technology

[0002] In power systems, reactive power switching devices are core operating components, and their operational stability directly affects the power factor and power quality of the power grid. Currently, most mainstream switching devices use mechanical switches, which still have some technical shortcomings, such as: 1) Mechanical switches have no zero-crossing control capability when switching on and off. At the moment of connection, they are prone to inrush current several times the rated current, which can cause the switch contacts to burn out and the capacitor to be damaged. At the same time, they can cause voltage fluctuations and harmonic pollution in the power grid, affecting the operation of precision electrical equipment.

[0003] 2) Conventional relays and contactors require continuous power to maintain their engaged state, resulting in high energy consumption over long periods. While some semiconductor switches support zero-crossing switching, they have large on-state voltage drops, high heat dissipation requirements, and lack a coordinated control mechanism with mechanical switches, making it difficult to balance switching accuracy with energy consumption costs.

[0004] Based on the above reasons, we propose a zero-crossing monitoring and protection device for reactive power switching voltage. Summary of the Invention

[0005] The purpose of this invention is to provide a reactive power switching switch voltage zero-crossing monitoring and protection device to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A reactive power switching switch voltage zero-crossing monitoring and protection device includes a monitoring module and a protection module. Both the monitoring module and the protection module are enclosed in a housing, and the two housings are mounted together. The monitoring module includes a controller, a semiconductor switch, a relay, a contactor, a zero-crossing detection module, and a communication module.

[0007] The protection module includes a heat dissipation component and a protection module control motherboard. The protection module control motherboard is equipped with an early warning unit and a fault diagnosis unit.

[0008] The protection module is installed on the side close to the heat dissipation component. The heat dissipation component includes a heat sink, a cooling fan, and heat-conducting fins. The heat sink is the main structure of the heat dissipation component. A heat-conducting grid is provided on the side of the heat sink close to the protection module, and an insulating barrier mesh is covered on the heat-conducting grid.

[0009] The heat sink contains heat-conducting fins, and a cooling fan is located on the side of the heat sink away from the protection module, extending outwards. Multiple temperature sensors are installed on the inner wall of the heat sink.

[0010] Preferably, the semiconductor switch uses parallel thyristors to connect the circuit at the voltage zero-crossing point and disconnect the circuit at the current zero-crossing point. After the semiconductor switch completes the switching action, the relay and contactor quickly short-circuit the current flowing through the main circuit, and their coils only consume power during the moment of state switching.

[0011] Preferably, the zero-crossing detection module monitors the grid voltage waveform in real time, controls the thyristors to turn on and off at the zero-crossing point, and has built-in protection circuitry including overvoltage, undervoltage, phase loss, and overheat protection functions. The controller coordinates the timing of the semiconductor switches and mechanical switches through commands.

[0012] Preferably, the early warning unit achieves early warning by working together with a digital filter and a prediction algorithm model. First, the digital filter removes the third and fifth harmonic interference in the power grid, and then the linear prediction model predicts the zero-crossing point in advance to avoid inrush current due to detection lag.

[0013] Preferably, the fault diagnosis unit has a built-in fault database. When a phase loss or overheating fault is detected, it automatically disconnects the switch, locates the faulty component through an algorithm, and pushes maintenance suggestions to the background.

[0014] Preferably, the communication module establishes a network connection with the backend, and triggers an immediate report when a fault or tripping occurs, transmitting the fault data to the backend via a 4G / 5G network.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This solution employs a semiconductor switch in conjunction with a zero-crossing detection module, enabling conduction at voltage zero-crossing points and disconnection at current zero-crossing points. This improves inrush current suppression, avoids impact on the power grid during switching, and extends the lifespan of capacitors and switch contacts. The zero-crossing detection module and linear prediction model preemptively eliminate 3rd, 5th, and 7th harmonic interference and predict zero-crossing points, reducing response delay and resolving the lag problem of traditional detection methods.

[0016] Comprehensive early warning and fault self-healing enhance system reliability. The early warning unit uses digital filters and linear prediction models to predict zero crossings, provide early warnings of transient overvoltages and capacitor lifespans, and intervene in potential risks in advance to prevent faults from occurring.

[0017] The fault diagnosis unit has a built-in database of multiple types of faults, which can locate faults such as phase loss, overheating, and contact aging within 100μs. It automatically disconnects the switch and pushes a visual report containing the fault type, possible causes, and maintenance steps. It also supports automatic adjustment of the buffer circuit when there is slight overvoltage, so as to achieve fault self-healing.

[0018] Highly efficient heat dissipation and safety protection ensure long-term stable operation. The heat dissipation components can adaptively absorb and dissipate heat inside the device, ensuring that the module temperature remains stable below the preset value, avoiding performance degradation caused by high temperature. The heat dissipation grid is covered with a fiberglass insulating barrier mesh, which has both dustproof and leakage prevention functions, further improving the device's environmental adaptability. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present invention.

[0020] Figure 2 This is a perspective view of the heat dissipation component and protection module control motherboard of the present invention.

[0021] Figure 3 This is a side perspective view of the heat dissipation component of the present invention.

[0022] In the diagram: 1 Monitoring module, 2 Semiconductor switch, 3 Protection module, 4 Heat dissipation component, 5 Protection module control motherboard, 6 Heat sink, 7 Cooling fan, 8 Thermal fins, 9 Thermal grid. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0024] Please see Figure 1-3 The present invention provides the following technical solution: A reactive power switching switch voltage zero-crossing monitoring and protection device includes a monitoring module 1 and a protection module 3. Both the monitoring module 1 and the protection module 3 are fitted with housings, and the two housings are mounted together. The monitoring module 1 includes a controller, a semiconductor switch 2, a relay, a contactor, and a zero-crossing detection module.

[0025] Semiconductor switch 2 uses parallel thyristors to connect the circuit at the voltage zero-crossing point and disconnect the circuit at the current zero-crossing point. After semiconductor switch 2 completes the switching action, the relay and contactor quickly short-circuit the current flowing through the main circuit. Their coils only consume power during the state switching instant and consume almost no power in steady state.

[0026] The zero-crossing detection module monitors the grid voltage waveform in real time, precisely controlling the thyristor to turn on and off at the zero-crossing point. It also features built-in protection circuitry, including overvoltage, undervoltage, phase loss, and overheat protection functions, enhancing system safety. The controller coordinates the timing of the actions of semiconductor switch 2 and the mechanical switch via commands.

[0027] The protection module 3 includes a heat dissipation component 4 and a protection module control motherboard 5. The protection module control motherboard 5 is equipped with an early warning unit and a fault diagnosis unit.

[0028] The early warning unit achieves early warning by working together with digital filters and prediction algorithm models. First, the digital filters remove the third and fifth harmonic interference in the power grid, and then the linear prediction model predicts the zero-crossing point in advance to avoid inrush current due to detection lag.

[0029] The fault diagnosis unit has a built-in fault database. When faults such as phase loss or overheating are detected, it automatically disconnects the switch, locates the faulty component through algorithms, and pushes maintenance suggestions to the background.

[0030] The protection module 3 is installed on the side close to the heat dissipation component 4, which absorbs and dissipates the heat inside the device.

[0031] The casing also houses a communication module that establishes a network connection with the backend via a 4G / 5G network. Normally, it sends data through scheduled reporting. In case of a fault or trip, it triggers an immediate reporting function, allowing the backend to keep track of the status of each device in a timely manner.

[0032] The controller uses an STM32F407 microprocessor, supports 16 digital inputs / 8 analog outputs, and has a response delay of ≤10μs. It receives switching commands from an external reactive power compensation controller via an RS485 interface and simultaneously sends real-time operating status data, such as the number of switching operations and the current voltage value, to the protection module 3.

[0033] Semiconductor switch 2 uses SiC silicon carbide MOSFET / C2M0080120D, with a conduction voltage drop ≤1.2V, switching frequency ≥100kHz, supporting conduction at voltage zero crossing point and disconnection at current zero crossing point, and inrush current suppression rate ≥98%, avoiding the impact on the power grid during switching.

[0034] The relay is a magnetic latching type HFE105, and the contactor is a type CJX2-1210. The two work together: after the semiconductor switch 2 completes the zero-crossing switching, the relay / contactor quickly closes and shorts the main circuit current, consuming power only at the moment of state switching, which greatly reduces the operating energy consumption.

[0035] The zero-crossing detection module uses the high-precision voltage sampling chip ADS1115, a 16-bit ADC, and an RC low-pass filter to acquire the three-phase voltage waveforms of the power grid (A, B, and C) in real time. It first eliminates the interference of the 3rd, 5th, and 7th harmonics through a harmonic filtering algorithm and a linear prediction model, and then predicts the zero-crossing point in advance to ensure the precise timing of the semiconductor switch 2.

[0036] The early warning unit is linked with the prediction algorithm model through digital filters. In addition to conventional zero-crossing prediction, it can also provide early warning of transient overvoltage, early warning of capacitor life, and realize pre-emptive intervention.

[0037] The fault diagnosis unit has a built-in fault database covering 28 common fault categories, such as phase loss, overheating, and contact aging. It uses a feature value matching algorithm to locate faulty components. For example, if the current in phase A is detected to be 0, it is determined that phase A is missing, possibly due to a loose sampling line or burnt contactor contacts. A visual report containing the fault type, possible causes, and repair steps is pushed to the backend. It also supports fault self-healing, such as automatically adjusting the buffer circuit parameters in case of slight overvoltage without disconnecting the switch.

[0038] The protection circuit employs a common detection and response design, and its main function is to prevent electronic equipment from being damaged by overvoltage, overcurrent, surge, electromagnetic interference, or abnormal temperature.

[0039] The heat dissipation component 4 includes a heat dissipation box 6, a heat dissipation fan 7, and heat-conducting fins 8. The heat dissipation box 6 is the main structure of the heat dissipation component 4. A heat-conducting grid 9 is provided on the side of the heat dissipation box 6 near the protection module 3. An insulating barrier mesh covers the heat-conducting grid 9.

[0040] The heat sink 6 is equipped with heat-conducting fins 8. A cooling fan 7 is located on the side of the heat sink 6 away from the protection module 3, extending outwards. The cooling fan 7 dissipates heat when it rotates. Multiple temperature sensors are installed on the inner wall of the heat sink 6.

[0041] The heat sink 6 is made of 6061 aluminum alloy with an anodized interior. The heat-conducting grid 9 is covered with a fiberglass insulating mesh to prevent dust from entering and avoid the risk of leakage. The heat-conducting fins 8 are one-piece molded aluminum fins that are bonded to the power devices of the protection module 3 with thermal grease to conduct heat to the heat sink 6.

[0042] The cooling fan 7 uses a DC12V silent fan and supports speed adjustment. It works with the temperature sensor on the inner side wall of the heat sink 6 to achieve adaptive heat dissipation.

[0043] The communication module supports 4G / 5G+LoRa dual-mode communication and adopts a timed + triggered dual-mode. During normal operation, it reports data once every 5 minutes, including voltage, current, power factor, module temperature, and switching count. In case of fault or tripping, it triggers an immediate report within 10 seconds.

[0044] It supports manual modification of deployment and switching parameters via backend, eliminating the need for on-site operation. It also features hierarchical access control to prevent accidental misoperation.

[0045] Device switching process: The reactive power compensation controller issues a switching command → the zero-crossing detection module of monitoring module 1 collects the voltage waveform → the zero-crossing point is predicted → semiconductor switch 2 turns on at the zero-crossing point → the relay / contactor engages after 20ms → semiconductor switch 2 opens after a 50ms delay → inrush-free switching is completed. The switching process is the reverse: first, the relay / contactor is disconnected, and then semiconductor switch 2 is opened at the current zero-crossing point.

[0046] Protection linkage process: The temperature sensor detects that the module temperature is ≥70℃ → the warning unit of the protection module 3 is triggered → the cooling fan starts at high speed → if the temperature does not drop below 65℃ within 10 seconds → the control motherboard 5 issues a derating operation command → the number of capacitor banks switched is reduced → if the temperature continues to rise to 75℃ → all switches are disconnected and the background is reported.

[0047] Fault handling process: Phase A phase loss is detected → Fault diagnosis unit of protection module 3 locates the fault → Contactor is disconnected within 100μs → A phase loss is pushed to the background, suggesting checking the A phase sampling line or contactor contacts → Device is locked, and can only be restarted after manual reset or remote reset in the background.

[0048] Working principle: Monitoring module 1 is the core execution unit for switching operations. It uses a combination of semiconductor switch 2 and mechanical switch (relay / contactor) with zero-crossing detection to ensure accurate switching. The controller receives on / off commands from an external reactive power compensation controller via an interface.

[0049] The zero-crossing detection module collects three-phase voltages, first using an RC low-pass filter and algorithm to remove 3rd / 5th / 7th harmonics, and then using a linear prediction model to predict the zero-crossing point in advance, ensuring the accuracy of the detection.

[0050] Throwing and cutting motion execution: Step 1: When the controller detects the zero-crossing point of the voltage, it triggers semiconductor switch 2 to turn on. Since the voltage at the zero-crossing point is close to 0, inrush current is completely avoided.

[0051] Step 2: After 20ms, the magnetic latching relay and contactor engage, short-circuiting the main circuit current—the two only consume power during the moment of switching, and there is no power consumption in steady state, reducing operating costs.

[0052] Step 3: Semiconductor switch 2 opens after a 50ms delay, completing the inrush-free connection. The disconnection process is the reverse: first disconnect the mechanical switch, then let semiconductor switch 2 open at the current zero-crossing point to avoid arcing.

[0053] Protection module 3 features a three-in-one protection system combining early warning, intervention, and diagnosis. Its principle is as follows: The temperature sensor monitors the internal temperature of the device in real time. When the temperature is ≥70℃, the cooling fan is activated at high speed. If the temperature does not drop below 65℃ within 10 seconds, derating is triggered to reduce the number of switched capacitors. If the temperature rises to 75℃, all switches are disconnected and the system is reported to the backend.

[0054] The heat sink 6 and the heat-conducting fins 8 are bonded to the power devices with thermal grease to quickly conduct heat. The glass fiber mesh of the heat-conducting grid 9 can also prevent dust and leakage.

[0055] The fault diagnosis unit has a built-in database of multiple types of faults and uses a feature value matching algorithm to locate problems. For example, if the current of phase A is detected to be 0, it directly determines that phase A is missing and associates it with possible causes such as loose sampling line or burnt contactor contacts.

[0056] Minor faults can be automatically adjusted to achieve self-healing. Severe faults will disconnect the switch within 100μs and push a visual report containing the fault type and repair steps to the background. Manual or remote reset is required to restart.

[0057] The communication module serves as a bridge between the device and the back-end system. In the event of a fault or trip, it triggers an immediate report within 10 seconds, allowing the back-end system to grasp the situation immediately without needing to check on-site, which is very convenient.

Claims

1. A reactive power switching switch voltage zero-crossing monitoring and protection device, comprising a monitoring module (1) and a protection module (3), characterized in that: Both the monitoring module (1) and the protection module (3) are equipped with housings on their outer sides, and the two housings are installed together; the monitoring module (1) includes a controller, a semiconductor switch (2), a relay, a contactor, a zero-crossing detection module and a communication module; The protection module (3) includes a heat dissipation component (4) and a protection module control motherboard (5). The protection module control motherboard (5) is equipped with an early warning unit and a fault diagnosis unit. The protection module (3) is installed on the side close to the heat dissipation component (4). The heat dissipation component (4) includes a heat dissipation box (6), a heat dissipation fan (7) and heat-conducting fins (8). The heat dissipation box (6) is the main structure of the heat dissipation component (4). A heat-conducting grid (9) is provided on the side of the heat dissipation box (6) close to the protection module (3). An insulating barrier mesh is covered on the heat-conducting grid (9). The heat sink (6) is equipped with heat-conducting fins (8), and a heat sink fan (7) is provided on the side of the heat sink (6) away from the protection module (3), extending to the outside; multiple temperature sensors are provided on the inner wall of the heat sink (6).

2. The reactive power switching switch voltage zero-crossing monitoring and protection device according to claim 1, characterized in that: The semiconductor switch (2) uses parallel thyristors to connect the circuit at the voltage zero-crossing point and disconnect the circuit at the current zero-crossing point; after the semiconductor switch (2) completes the switching action, the relay and contactor quickly short-circuit the current flowing through the main circuit, and their coils only consume power at the moment of state switching.

3. The reactive power switching switch voltage zero-crossing monitoring and protection device according to claim 2, characterized in that: The zero-crossing detection module detects the grid voltage waveform in real time, controls the thyristor to turn on and off at the zero-crossing point, and has a built-in protection circuit including overvoltage, undervoltage, phase loss and overheat protection functions; the controller coordinates the action sequence of the semiconductor switch (2) and the mechanical switch through instructions.

4. The reactive power switching switch voltage zero-crossing monitoring and protection device according to claim 2, characterized in that: The early warning unit achieves early warning by working together with digital filters and prediction algorithm models. First, the digital filters remove the third and fifth harmonic interference in the power grid, and then the linear prediction model predicts the zero-crossing point in advance to avoid inrush current due to detection lag.

5. A reactive power switching switch voltage zero-crossing monitoring and protection device according to claim 2, characterized in that: The fault diagnosis unit has a built-in fault database. When a phase loss or overheating fault is detected, it automatically disconnects the switch, locates the faulty component through an algorithm, and pushes maintenance suggestions to the background.

6. The reactive power switching switch voltage zero-crossing monitoring and protection device according to claim 1, characterized in that: The communication module establishes a network connection with the backend, and triggers an immediate report when a fault or trip occurs, transmitting the fault data to the backend via the 4G / 5G network.

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