Capacitor power switch with fault diagnosis function and method

Abstract

The present invention provides a capacitor power-taking switch and method with a fault diagnosis function, the switch includes a high-voltage capacitor, a protection module, a power-taking unit and a measurement and control unit, a current measurement sensor is connected between the protection module and the grounding terminal, the second end of the high-voltage capacitor is connected to the first end of the protection module, the second end of the protection module is connected to the first end of the current measurement sensor, the second end of the current measurement sensor is grounded, the first end of the power-taking unit is connected to the first end of the protection module, the second end of the power-taking unit is connected to the second end of the current measurement sensor, the third end of the power-taking unit outputs a voltage signal to the measurement and control unit, and the third end of the current measurement sensor outputs a current signal of the protection module to the measurement and control unit. The present invention uses the existing resources of the FTU equipped with the existing switch to analyze the data to obtain the opening and closing time characteristics of the switch, thereby judging whether the switch is in a normal state.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution automation, and in particular to a capacitor power switch with a fault diagnosis function and a fault diagnosis method applied to the switch. Background Art

[0002] As the link between the distribution network and the user, the reliable operation of the distribution switch is of great significance to ensure the reliability of power supply. The distribution switch plays two roles in the distribution network: one is the control role, that is, according to the operation requirements of the distribution network, a part of the electrical equipment or line is put into or out of operation; the other is the protection role, that is, when the electrical equipment or line fails, the faulty part is quickly cut off from the power grid through the action of relay protection and automatic devices to protect the trouble-free operation of the power grid. With the development of the economy and the transformation of the national distribution network and the deepening of the construction of smart grids, there is a huge demand for pole switches, especially primary and secondary fusion pole switches. Hundreds of thousands of units are put into use every year. In recent years, the primary and secondary fusion pole switches for capacitor power are gradually replacing the primary and secondary fusion pole switches for traditional PT power due to the advantages of no explosion hazards, so the fault diagnosis of the primary and secondary fusion pole switches for capacitor power is of great significance, especially the early fault diagnosis.

[0003] The current capacitor power supply switches are passively replaced after a fault occurs, and lack measures to prevent early faults of the switch. The capacitor power supply primary and secondary fusion switches are highly intelligent distribution automation switches with functions such as current and voltage sampling, line protection, and communication, but these resources are not currently being used to the maximum extent.

[0004] There are several mechanical characteristic parameters of the switch, but in actual use, the most important factor affecting the reliability of multiple power supply is the opening and closing characteristics, and in the opening and closing characteristics, the opening and closing time and the different phases are the two most important parameter values. The mechanical failure of the switch will eventually manifest as abnormal opening and closing. Therefore, through the opening and closing process, it is basically clear whether the current operation of the switch is in a normal state. The conventional method for analyzing the opening and closing process is to install a displacement sensor inside the switch and analyze it using the displacement-current and displacement-voltage curves. However, this method requires the switch to be redesigned, which increases the cost. In particular, it is impossible to add a displacement sensor to a molded, stable switch and a large number of switches that have been put into operation. Summary of the invention

[0005] The main purpose of the present invention is to provide a capacitor power switch with a fault diagnosis function, which does not require the addition of a displacement sensor. By analyzing the existing resources of the FTU equipped with the existing switch, the opening and closing time characteristics of the switch can be obtained, thereby judging whether the switch is in a normal state.

[0006] Another object of the present invention is to provide a fault diagnosis method for a capacitor power switch with a fault diagnosis function, which does not require the addition of a displacement sensor and can obtain the opening and closing time characteristics of the switch by analyzing the data through the existing resources of the FTU equipped with the existing switch, thereby determining whether the switch is in a normal state.

[0007] In order to achieve the above main purpose, the present invention provides a capacitor power switch with a fault diagnosis function, including a high-voltage capacitor, a protection module, a power supply unit with electrical isolation and a measurement and control unit, a current measurement sensor is connected between the protection module and the grounding terminal, the first end of the high-voltage capacitor is connected to any one of the three phases A, B, and C of the power line, the second end of the high-voltage capacitor is connected to the first end of the protection module, the second end of the protection module is connected to the first end of the current measurement sensor, the second end of the current measurement sensor is grounded, the first end of the power supply unit is connected to the first end of the protection module, the second end of the power supply unit is connected to the second end of the current measurement sensor, the third end of the power supply unit outputs a voltage signal to the measurement and control unit, and the third end of the current measurement sensor outputs a current signal of the protection module to the measurement and control unit, wherein the measurement and control unit is used to measure voltage and current signals and control the switch, and when the measurement and control unit detects that the sampling data is abnormal, it sends an alarm message to the master station.

[0008] In a further solution, the high-voltage capacitor, protection module, and power supply unit can be supplied in single-phase, two-phase, or three-phase power supply mode.

[0009] In a further solution, the protection module is a varistor array, which is composed of a number of varistors connected in series. Each varistor is set according to a creepage distance or an insulation level spacing, and is arranged in series on the circuit board of the protection module.

[0010] In a further solution, the power supply unit includes an isolation transformer, a rectifier and filter circuit, and a voltage stabilizing circuit. The primary coil of the isolation transformer is connected to both ends of the protection module, and both ends of the secondary coil of the isolation transformer are connected to the rectifier and filter circuit. The voltage stabilizing circuit is arranged at the output end of the rectifier and filter circuit, and the output end of the rectifier and filter circuit is connected to the input end of the voltage stabilizing circuit.

[0011] In order to achieve the above-mentioned another purpose, the present invention provides a fault diagnosis method for a capacitor power switch with a fault diagnosis function, the capacitor power switch adopts the above-mentioned capacitor power switch, and the method comprises the following steps: removing the PT, adopting the capacitor power switch to draw power, obtaining the high-voltage AC power on the power grid, and performing voltage reduction processing on it; when a switch-on / off signal is detected, the measurement and control unit issues a switch-on / off command to connect the power supply line; obtaining the switch-on / off time of the three phases A, B, and C, which are Ta, Tb, and Tc respectively, and comparing the absolute values ​​of Ta-Tb, Ta-Tc, and Tb-Tc with the standard values. If the absolute value is greater than the standard value, it can be determined that the switch has different phase abnormalities, and an alarm message is sent to the main station; if any time among Ta, Tb, and Tc is greater than the standard maximum switch-on / off time, it can be determined that the switch has a switch-on / off abnormality, and an alarm message is sent to the main station.

[0012] In a further solution, for a permanent magnet mechanism switch, obtaining the opening / closing time specifically includes: starting timing from when an action instruction from the measurement and control unit is issued until the moment when a current signal in the line is detected, which can be determined as the opening / closing time.

[0013] In a further solution, for a permanent magnet mechanism switch, obtaining the opening / closing time specifically includes: starting timing from when an action instruction from the measurement and control unit is issued until the moment a voltage signal is detected on the load side of the switch, which can be determined as the opening / closing time.

[0014] In a further solution, when the voltage difference between the load side and the power side of the switch exceeds a predetermined value, it is determined that the switch contacts are in poor contact, and an alarm message is sent to the master station.

[0015] In a further solution, when the measurement and control unit issues a closing command, the closing circuit is connected - the closing coil is energized - the contacts are connected - the power supply line is connected.

[0016] In a further solution, for the spring-operated switch, obtaining the opening / closing time specifically includes: starting timing from the issuance of the action command from the measurement and control unit until the moment when a voltage signal is detected on the load side of the switch, and then subtracting the relay action time to obtain the switch opening / closing time.

[0017] It can be seen that the present invention provides a simple hardware modification to the existing modules, so as to perform fault diagnosis on the protection module and the power supply module with electrical isolation. By utilizing the existing resources of the switch and FTU and analyzing the sampled data, the opening and closing phase conditions and the opening and closing time during the operation of the switch can be obtained, thereby judging the action characteristics of the switch and making early diagnosis of the switch fault.

[0018] Therefore, the present invention does not increase the hardware overhead, but uses sampling data to analyze the different phases and opening and closing times of the switch and the voltage difference between the power supply side and the load side, so as to make early diagnosis of the mechanical failure of the switch, and change "passive power outage replacement" into "active prevention", which is beneficial to improving the power supply reliability; the protection circuit and the power supply circuit after the high-voltage power supply capacitor are divided into a protection module and a power supply module with electrical isolation, and the FTU detects them. When there is a fault, an alarm signal can be sent to the main station to remind the operation and maintenance personnel to perform fast and accurate online power replacement, thereby avoiding power outages, reducing economic losses from power outages, and improving power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an embodiment of a capacitor power supply switch with a fault diagnosis function of the present invention.

[0020] Figure 2 It is a circuit schematic diagram of a power taking unit in an embodiment of a capacitive power taking switch with a fault diagnosis function of the present invention.

[0021] Figure 3 The present invention is a circuit diagram of a protection module in a capacitor power switch embodiment with a fault diagnosis function.

[0022] Figure 4 The present invention discloses a circuit schematic diagram of a closing time timing starting point circuit in an embodiment of a capacitor power taking switch with a fault diagnosis function.

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] An embodiment of a capacitor power switch with a fault diagnosis function:

[0026] See also Figure 1A capacitor power switch with a fault diagnosis function of the present invention comprises a high-voltage capacitor 10, a protection module 20, a power supply unit 30 with electrical isolation and a measurement and control unit 40, a current measurement sensor 50 is connected between the protection module 20 and the grounding terminal, a first end of the high-voltage capacitor 10 is connected to any one of the three phases A, B and C of the power line, a second end of the high-voltage capacitor 10 is connected to the first end of the protection module 20, a second end of the protection module 20 is connected to the first end of the current measurement sensor 50, a second end of the current measurement sensor 50 is grounded, a first end of the power supply unit 30 is connected to the first end of the protection module 20, a second end of the power supply unit 30 is connected to the second end of the current measurement sensor 50, a third end of the power supply unit 30 outputs a voltage signal to the measurement and control unit 40, and a third end of the current measurement sensor 50 outputs a current signal of the protection module 20 to the measurement and control unit 40, wherein the measurement and control unit 40 is used to measure voltage and current signals and control the switch, and when the measurement and control unit 40 detects that the sampling data is abnormal, an alarm message is sent to the master station.

[0027] The high-voltage capacitor 10 , the protection module 20 , and the power supply unit 30 may be supplied in a single-phase, two-phase, or three-phase power supply mode.

[0028] For example, in the three-phase power supply mode, three high-voltage capacitors 10 are provided, and the three capacitors can be easily connected in parallel by providing leads on the terminal row. The terminal row can also be provided so that the three capacitors correspond to the three-phase capacitors C1 respectively, which can be applied to single-phase or three-phase situations at the same time.

[0029] See also Figure 2 The power taking unit 30 includes an isolation transformer B1, a rectifier and filter circuit, and a voltage stabilizing circuit. The primary side coil of the isolation transformer B1 is connected to both ends of the protection module 20, and both ends of the secondary side coil of the isolation transformer B1 are connected to the rectifier and filter circuit. A voltage stabilizing circuit is provided at the output end of the rectifier and filter circuit, and the output end of the rectifier and filter circuit is connected to the input end of the voltage stabilizing circuit.

[0030] Specifically, the voltage signal V1 is connected to one end of the high-voltage capacitor 10 (C1), and the other end of the high-voltage capacitor 10 is simultaneously connected to one end of the primary coil of the isolation transformer B1, and the other end of the primary coil of the isolation transformer B1 is grounded. The protection module 20 and the current measurement sensor 50 are connected in parallel at both ends of the primary coil of the isolation transformer B1.

[0031] The two ends of a set of secondary coils of the isolation transformer B1 are connected to the two ends of the resistor R1, which is a damping resistor. The two ends of a set of secondary coils of the isolation transformer B1 are connected to the input end of the rectifier bridge circuit, which is a full-wave rectifier circuit composed of diodes D1 to D4. A capacitor C3 is connected in parallel between the output ends of the rectifier bridge circuit. The rectifier bridge circuit composed of diodes D1 to D4 and the capacitor C3 that plays a filtering role constitute the above-mentioned rectifier filter circuit.

[0032] A voltage divider consisting of resistors R2-R3 connected in series and a voltage stabilizer D5 are connected in parallel between the positive and negative outputs of the rectifier bridge circuit. The voltage stabilizer D5 is implemented by a controllable precision voltage stabilizer of model TL431. The cathode of the voltage stabilizer D5 is connected to the positive output of the rectifier bridge circuit, the anode is connected to the negative output of the rectifier bridge circuit, and the reference electrode of the voltage stabilizer D5 is connected between the resistors R2-R3. The voltage across the voltage stabilizer D5 (TL431) depends on the resistance of the resistors R2-R3. It can be known from the common knowledge in the art that the voltage at the output of the voltage stabilizer D5 is U=(1+R2 / R3)·2.5V. Therefore, by adjusting the resistance of the resistors R2-R3, the voltage at the output of the voltage stabilizer D5 can be within the operating voltage range required by the input of the voltage conversion circuit. The resistors R2-R3 and the voltage stabilizer D5 constitute the above-mentioned voltage stabilizer circuit.

[0033] The voltage at the output of the voltage regulator device D5 is connected to the input of the voltage regulator chip U2. The voltage regulator chip U2 can be implemented using a common DC / DC voltage regulator chip on the market according to the power supply requirements of the powered equipment. The voltage signal output by the voltage regulator chip U2 is sent to the measurement and control unit 40 (U3).

[0034] In this embodiment, the high-voltage capacitor 10 is formed by connecting a plurality of CB81 cylindrical film capacitors with a DC withstand voltage of 80 kV in series.

[0035] It can be seen that the high-voltage capacitor 10 can be implemented by a single capacitor or by multiple capacitors connected in series. The high-voltage capacitor 10 of this embodiment uses a high-voltage ceramic capacitor, and the special series structure is suitable for long-term reliable operation under high voltage.

[0036] Furthermore, the protection module 20 is a varistor array. Figure 3 , which includes an input terminal 100, a varistor array and an output terminal 200. The varistor array is composed of a number of varistors connected in series, such as varistors RV1 to RV30. Each varistor is set according to the creepage distance or insulation level spacing, and is arranged in series on the circuit board of the protection module 20 in sequence.

[0037] Preferably, the varistor is a metal oxide varistor, which has a fast reaction speed and a fast response time of less than 10ns. The fast response can ensure better protection of the device or port from the influence of surge current.

[0038] The protection module 20 of this embodiment adopts the type of varistor array, which is made into a separate module and placed at the front end of the power taking unit 30 and connected in parallel with the power taking unit 30. It can resist surge impact, especially impact with a long duration. By dispersing the concentrated heat, the temperature rise of each device under extreme conditions is significantly reduced, thereby preventing the device from being damaged by excessive temperature rise, achieving the purpose of protecting the device and improving the reliability of the overall system.

[0039] In practical applications, the power-taking circuit of this embodiment is specifically as follows: the first conductor 1 is connected to a phase of the power line (such as phase A in the figure). Because the reactance of the high-voltage capacitor 10 is high, the voltage drop is greatly reduced after passing through the high-voltage capacitor 10. After the current flows through the second conductor 2, there are two branches. However, when the line voltage is normal, the voltage at both ends of the protection module 20 is relatively low and cannot reach the starting voltage, so that the protection module 20 does not work, that is, almost no current flows; at this time, all the current flowing out of the high-voltage capacitor 10 flows through the "power-taking module with electrical isolation", and then enters the ground through the third conductor 3 and the current measurement sensor 50.

[0040] If the high-voltage capacitor 10 breaks down and short-circuits, the voltage across the protection module 20 will rise sharply, and the protection module 20 will immediately start working and current will begin to flow. Since the reactance of the "electrical isolation power module" is high, the current flowing through it is negligible compared to the protection module 20. Therefore, when the high-voltage capacitor 10 breaks down, the current on the first wire 1, the second wire 2, the third wire 3 and the fourth wire 4 will increase sharply.

[0041] If the entire path of the second wire 2, the third wire 3 and the protection module 20 is ensured to have a sufficient wire diameter and are all made of the same copper material, but the wire diameter of the first wire 1 is much smaller than the wire diameter of the above path, then when the current path composed of the first wire 1, the high-voltage capacitor 10, the second wire 2, the protection module 20 and the third wire 3 flows through a large breakdown current, due to the different heat generation per unit length: if the wire diameter of the second wire 2 and the third wire 3 is twice that of the first wire 1, the instantaneous heat generation per unit length on the first wire 1 is 4 times that of the second wire 2 and the third wire 3. When the current rises sharply and the wire has no time to dissipate heat, the temperature rise on the first wire 1 will far exceed that of the second wire 2 and the third wire 3 and the protection module 20, so the first wire 1 must be melted first. When the first wire 1 is melted, the high voltage is isolated, so that the protection module 20 and the power supply module with electrical isolation that may be touched become a safe area, eliminating the risk of electric shock caused by burning the second wire 2, the third wire 3, that is, the internal conductor of the protection module 20.

[0042] An embodiment of a fault diagnosis method for a capacitor power switch with a fault diagnosis function:

[0043] The present invention provides a fault diagnosis method for a capacitor power switch with a fault diagnosis function. The capacitor power switch adopts the above-mentioned capacitor power switch, and the method comprises the following steps: removing the PT, adopting the capacitor power switch to draw power, obtaining the high-voltage AC power on the power grid, and performing voltage reduction processing on it; when a switch-on / off signal is detected, the measurement and control unit 40 issues a switch-on / off instruction to connect the power supply line; obtaining the switch-on / off time of the three phases A, B, and C, which are Ta, Tb, and Tc respectively, and comparing the absolute values ​​of Ta-Tb, Ta-Tc, and Tb-Tc with the standard specified values. If the absolute value is greater than the standard specified value, it can be determined that the switch has different phase abnormalities, and an alarm message is sent to the main station; if any time among Ta, Tb, and Tc is greater than the standard maximum switch-on / off time, it can be determined that the switch has a switch-on / off abnormality, and an alarm message is sent to the main station.

[0044] For example, the standard value of the spring-operated switch in this embodiment is a maximum of 2 ms, as shown in Table (1):

[0045] Table (1)

[0046]

[0047] The standard maximum closing / opening time of the spring-operated switch in the above table (1) is 60ms / 45ms.

[0048] For the permanent magnet mechanism switch, obtaining the opening / closing time specifically includes: starting timing from when the action command of the measurement and control unit 40 is issued until the moment when the current signal of the line is detected, which can be determined as the opening / closing time.

[0049] For a permanent magnet mechanism switch, obtaining the opening / closing time specifically includes: starting timing from when an action instruction is issued by the measurement and control unit 40 until the moment when a voltage signal is detected on the load side of the switch, which can be determined as the opening / closing time.

[0050] Furthermore, when the voltage difference between the load side and the power side of the switch exceeds a predetermined value, it is determined that the switch contacts are in poor contact, and an alarm message is sent to the master station.

[0051] In addition, when the voltage difference between the load side and the power supply side exceeds a certain value, it can be judged that the switch contacts are in poor contact, and an alarm signal will be sent to the main station to remind the operation and maintenance personnel to carry out maintenance.

[0052] Furthermore, when the measurement and control unit 40 issues a closing command, the closing circuit is connected - the closing coil is energized - the contacts are connected - and the power supply line is connected.

[0053] For the spring-operated switch, obtaining the opening / closing time specifically includes: starting timing from the issuance of the action command of the measurement and control unit 40 until the moment when a voltage signal is detected on the load side of the switch, and then subtracting the relay action time to obtain the switch opening / closing time.

[0054] Specifically, for spring-operated switches whose opening and closing are controlled by relays, since the action time of each relay is different, the above-mentioned relay action time of generally 8ms is only an approximation.

[0055] In this embodiment, the closing circuit of the present invention is as follows Figure 4 As shown, Figure 4 It is the starting point circuit for closing time timing. The timing starts when the current is detected in the opening and closing circuit, and Ta, Tb and Tc are accurately measured.

[0056] When the single-chip microcomputer issues a trip command (i.e. when the control port value of the measurement and control unit is at a high level), the switch tube Q1 is turned on and the relay K1 is energized. At this time, the closing coil J1 is energized and a voltage is generated on the resistor R20. This voltage can be detected through AD sampling. This moment is used as the timing starting point for closing. In this way, the timing starting point of the closing time can be accurately obtained, thereby accurately measuring the closing time.

[0057] Similarly, by setting a similar opening time timing starting circuit, the opening time can be accurately measured.

[0058] In practical applications, the current measurement sensor 50 converts the actual current into a voltage signal, which is then converted into a digital signal by an AD converter after signal processing, and the measurement and control unit 40 then performs calculations on the digital signal.

[0059] When the switch is not closed, the current is zero.

[0060] The process of closing the switch is as follows: when the measurement and control unit 40 connected to the switch detects a closing signal (which may be a closing signal such as a key operation, remote control operation, or reclosing), the measurement and control unit 40 issues a closing command, the closing circuit is connected, the closing coil is energized, and the mechanism operates until the contacts are connected and the power supply line is connected. At the moment the switch is turned on, even if there is no load, there is a transformer behind the switch, which will generate current (transformer excitation generates surge current), and this current can be detected by the measurement and control unit 40 through the above-mentioned hardware circuit with high precision and wide range.

[0061] According to the type of mechanism, switches can be divided into spring-operated mechanism switches and permanent magnet mechanism switches. The two types of switches have different mechanism drive methods. The driving current of the spring-operated mechanism switch is relatively small, and generally relay contacts can be used. If relay control is used, the time for relay action should be deducted from the action time when calculating the closing time; while permanent magnet mechanism switches are generally driven by IGBTs. IGBTs have a fast response speed. It can be considered that after the action command is issued, the coil is immediately energized without delay, that is, it acts instantly and simultaneously. In addition, the action speeds of the two switches are also quite different.

[0062] In summary, if the timing starts from the moment the action command of the measurement and control unit 40 is issued to the moment when the current is detected in the line, for the permanent magnet mechanism switch, this period of time is the switch closing time; for the spring-operated mechanism switch, this period of time minus the relay action time (generally 8ms) is the switch closing time.

[0063] Assume that the closing time of phases A, B and C is Ta, Tb and Tc respectively. If the absolute values ​​of Ta-Tb, Ta-Tc and Tb-Tc are compared with the standard values, if they are greater than the standard values, it can be judged that the switch has abnormalities at different stages. An alarm message can be sent to the main station so that the operation and maintenance personnel can handle it in time.

[0064] If any of Ta, Tb and Tc is greater than the standard maximum closing time, it can be determined that the switch has a closing abnormality; especially when a certain value is much greater than the normal closing time, it can be determined that the switch is stuck, and an alarm message can be sent to the main station to remind the operation and maintenance personnel to deal with it in time.

[0065] Since serious failures of switches are generally a gradual process, operation and maintenance personnel can be informed of early abnormal conditions of the switch closing and prevent failures from occurring.

[0066] Similarly, the fault diagnosis of the opening process can be measured by measuring the current.

[0067] In this embodiment, the voltage signal is outputted by the power taking unit 30 with electrical isolation, and after signal processing, it is converted into a digital signal by an AD converter, and the measurement and control unit 40 then performs calculation processing on the digital signal.

[0068] When the switch is not closed, the voltage on the load side of the switch is zero.

[0069] The switch closing process is as follows: when the measurement and control unit 40 connected to the switch detects a closing signal (which may be a closing signal such as a button operation, remote control operation, or reclosing), the measurement and control unit 40 issues a closing command, the closing circuit is connected, the closing coil is energized, and the mechanism operates until the contacts are connected and the power supply line is connected. The measurement and control unit 40 in the above hardware circuit can detect the voltage on the load side of the switch.

[0070] Similar to the above-mentioned method of measuring current, if the timing starts from the issuance of the closing action command of the measurement and control unit 40 to the moment when the voltage is detected on the load side of the switch, for the permanent magnet mechanism switch, this period of time is the switch closing time; for the spring-operated mechanism switch, this period of time minus the relay action time (generally 8ms) is the switch closing time.

[0071] Similarly, assuming that the closing times of phases A, B and C are Ta, Tb and Tc respectively, if the absolute values ​​of Ta-Tb, Ta-Tc and Tb-Tc are compared with the standard values, if they are greater than the standard values, it can be determined that the switches have abnormalities at different times, and an alarm message can be sent to the main station so that the operation and maintenance personnel can handle it in time.

[0072] If any of Ta, Tb and Tc is greater than the standard maximum closing time, it can be determined that the switch has a closing abnormality; especially when a certain value is much greater than the normal closing time, it can be determined that the switch is stuck, and an alarm message can be sent to the main station to remind the operation and maintenance personnel to deal with it in time.

[0073] Similarly, the fault in the opening process can be diagnosed by measuring the voltage on the power supply side and the load side.

[0074] In addition, when the voltage difference between the load side and the power supply side exceeds a certain value, it can be judged that the switch contacts are in poor contact, and an alarm signal will be sent to the main station to remind the operation and maintenance personnel to carry out maintenance.

[0075] The present invention makes a simple hardware modification to the existing modules, and can perform fault diagnosis on the protection module 20 and the power supply module with electrical isolation, as follows:

[0076] (1) Fault diagnosis of the protection module 20: Connect a current measurement sensor 50 between the protection module 20 and the ground terminal. When the protection module 20 is normal, the current is in the order of 10μA, otherwise a fault occurs. The fault may generally be that the varistor is short-circuited or open-circuited due to high-energy lightning strikes. When short-circuited, the current is in the mA level, and when open-circuited, the current is 0.

[0077] (2) Fault diagnosis of power supply module with electrical isolation: The fault diagnosis of this module is very simple. It only requires testing the output voltage of the module. When the output is the design voltage, generally 27V (supplying batteries or supercapacitors for energy storage), it is normal. When it deviates from this voltage by a large amount, and when the current of the protection module 20 is normal or zero, it is judged that the module is damaged.

[0078] When the above two modules are damaged, the measurement and control unit 40 transmits the fault information to the main station, notifies the operation and maintenance personnel to repair, and can replace them without power outage with the help of special tools.

[0079] Therefore, the present invention does not increase the hardware overhead, but uses the current sampling data to analyze the switch phases and the opening and closing time, so as to make an early diagnosis of the switch fault; does not increase the hardware overhead, but uses the voltage sampling data to analyze the switch phases and the opening and closing time, so as to make an early diagnosis of the switch fault; by adding hardware detection of the opening and closing circuit current detection, the switch phases and the opening and closing time data can be accurately obtained, so as to make an early diagnosis of the switch fault more accurately; when detecting the voltage method data, when the voltage difference between the load side and the power supply side exceeds a certain value, it can be judged that the switch contacts are in poor contact, and an alarm signal will be sent to the main station to remind the operation and maintenance personnel to carry out maintenance; the protection circuit and the power removal circuit after the high-voltage power supply capacitor are divided into a protection module 20 and a power supply unit 30 with electrical isolation, and the FTU detects them. When there is a fault, an alarm signal can be sent to the main station to remind the operation and maintenance personnel to carry out maintenance.

[0080] It can be seen that the present invention provides a simple hardware modification to the existing modules, so as to perform fault diagnosis on the protection module 20 and the power supply module with electrical isolation. By utilizing the existing resources of the switch and FTU and analyzing the sampled data, the opening and closing phase conditions and the opening and closing time during the operation of the switch can be obtained, thereby judging the action characteristics of the switch and making early diagnosis of the switch fault.

[0081] Therefore, the present invention does not increase the hardware overhead, but uses sampling data to analyze the different phases and opening and closing times of the switch and the voltage difference between the power supply side and the load side, so as to make early diagnosis of the mechanical failure of the switch, and change "passive power outage replacement" into "active prevention", which is beneficial to improving the power supply reliability; the protection circuit and the power supply circuit after the high-voltage power supply capacitor are divided into a protection module 20 and a power supply module with electrical isolation, and the FTU detects them. When there is a fault, an alarm signal can be sent to the main station to remind the operation and maintenance personnel to perform fast and accurate online power replacement, thereby avoiding power outages, reducing economic losses caused by power outages, and improving power supply reliability.

[0082] It should be noted that the above are only preferred embodiments of the present invention, but the design concept of the invention is not limited thereto, and any non-substantial modifications made to the present invention using this concept also fall within the protection scope of the present invention.

Claims

1. A capacitive power switch with fault diagnosis function, characterized in that: include: A high-voltage capacitor, a protection module, a power-taking unit with electrical isolation, and a measurement and control unit, wherein a current measurement sensor is connected between the protection module and the ground terminal, the first end of the high-voltage capacitor is connected to any one of the three phases A, B, and C of the power line, the second end of the high-voltage capacitor is connected to the first end of the protection module, the second end of the protection module is connected to the first end of the current measurement sensor, the second end of the current measurement sensor is grounded, the first end of the power-taking unit is connected to the first end of the protection module, the second end of the power-taking unit is connected to the second end of the current measurement sensor, the third end of the power-taking unit outputs a voltage signal to the measurement and control unit, and the third end of the current measurement sensor outputs a current signal of the protection module to the measurement and control unit, wherein the measurement and control unit is used to measure voltage and current signals and control the switch, and when the measurement and control unit detects that the sampling data is abnormal, it sends an alarm message to the master station; The high-voltage capacitor, protection module and power supply unit can be powered by single-phase, two-phase or three-phase power supply mode; The protection module is a varistor array, which is composed of a plurality of varistors connected in series. Each of the varistors is set according to a creepage distance or an insulation level spacing, and is sequentially arranged in series on a circuit board of the protection module.

2. The capacitive power switch according to claim 1, characterized in that: The power supply unit includes an isolation transformer, a rectifier and filter circuit, and a voltage stabilizing circuit. The primary coil of the isolation transformer is connected to both ends of the protection module, and both ends of the secondary coil of the isolation transformer are connected to the rectifier and filter circuit. The voltage stabilizing circuit is arranged at the output end of the rectifier and filter circuit, and the output end of the rectifier and filter circuit is connected to the input end of the voltage stabilizing circuit.

3. A fault diagnosis method for a capacitor power switch with a fault diagnosis function, characterized in that: The capacitive power switch is the capacitive power switch according to claim 1 or 2, and the method comprises the following steps: Remove the PT and use a capacitor power switch to obtain high-voltage AC power from the power grid and then reduce its voltage. When an opening / closing signal is detected, the measurement and control unit issues an opening / closing command to connect the power supply line; Obtain the opening / closing time of the three phases A, B, and C, which are Ta, Tb, and Tc respectively, and compare the absolute values ​​of Ta-Tb, Ta-Tc, and Tb-Tc with the standard values. If the absolute value is greater than the standard value, it can be determined that the switch has an abnormality in different periods, and send an alarm message to the master station; If any of the times Ta, Tb and Tc is greater than the standard maximum opening / closing time, it can be determined that the switch has an opening / closing abnormality, and an alarm message is sent to the master station.

4. The method according to claim 3, characterized in that: For a permanent magnet mechanism switch, the obtaining of the opening / closing time specifically includes: starting timing from when an action instruction from the measurement and control unit is issued until the moment when a current signal in the line is detected, which can be determined as the opening / closing time.

5. The method according to claim 3, characterized in that: For a permanent magnet mechanism switch, the obtaining of the opening / closing time specifically includes: starting timing from when an action instruction from the measurement and control unit is issued until the moment when a voltage signal is detected on the load side of the switch, which can be determined as the opening / closing time.

6. The method according to claim 5, characterized in that: When the voltage difference between the load side and the power side of the switch exceeds a predetermined value, it is determined that the switch contacts are in poor contact and an alarm message is sent to the master station.

7. The method according to claim 3, characterized in that: When the measurement and control unit issues a closing command, the closing circuit is connected - the closing coil is energized - the contacts are connected - and the power supply line is connected.

8. The method according to claim 5, characterized in that: For the spring-operated switch, the obtaining of the opening / closing time specifically includes: starting timing from the issuance of the action command of the measurement and control unit until the moment when a voltage signal is detected on the load side of the switch, and then subtracting the relay action time to obtain the switch opening / closing time.

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