Passive relay protection device and protection switch

Abstract

The utility model discloses a passive relay protection device and a protection switch. The protection device specifically comprises a control module; the monitoring module is used for acquiring power supply parameters of power transmission lines; the driving circuit is used for driving the protection switch to execute a tripping action; the super capacitor is used for providing energy for executing a tripping action for the protection switch; the energy supply module comprises a CT power taking unit and a conversion unit; the input end of the CT power taking unit is electrically connected with the power transmission line, and the output end of the CT power taking unit is electrically connected with the conversion unit; the output end of the conversion unit is electrically connected with the control module and the super capacitor. The CT electricity taking unit is used for obtaining electric energy from a power transmission line, and the conversion unit is used for converting the obtained electric energy into working voltage of the passive relay protection device and charging voltage of the super capacitor. According to the passive relay protection device provided by the utility model, when a short-circuit fault occurs in a power transmission line, the super capacitor can complete charging in a short time, so that the protection switch can trip in time.

Description

TECHNICAL FIELD

[0001] The utility model relates to but not limited to the relay protection device field especially, and protection switch is provided in a kind of passive relay protection device. BACKGROUND

[0002] Relay protection device is a kind of automatic protection device applied to transmission line, its working principle is to collect current and voltage signal in power system, and is analyzed by microprocessor or logic circuit to detect overcurrent, overvoltage, short circuit and other abnormal conditions, once these abnormalities are detected and need to be executed protection action according to the preset protection logic and fixed value, device will control relay drive circuit breaker or disconnecting switch to cut off fault part, to prevent the occurrence of power accident. Nowadays, with the increasing requirement of power reliability of transmission line, the reliability of protection device also needs to be improved, and active protection device is limited by the reliability of working power supply, which can cause the protection device to fail to work when the working power supply fails, therefore, in the existing relay protection device, passive relay protection device is mainly used, and passive relay protection device is usually powered by additional self-provided battery for relay protection device.

[0003] In passive relay protection device, most of them are through super capacitor discharge to provide execution tripping protection action electric energy for protection switch. Super capacitor needs to be recharged after discharging to continue to use, and the charging of super capacitor in passive relay protection device depends on self-provided battery. However, the charging rate of super capacitor by self-provided battery is affected by battery specification, and the charging speed is usually slow, and the charging time is too long. If the charging time is too long, after the first super capacitor discharge drives protection switch to trip, when the transmission line fails again in a short time, the super capacitor cannot provide energy to drive protection switch to trip, which may cause power accident. SUMMARY

[0004] The following is a summary of the subject matter described in detail in this document. This summary is not intended to limit the scope of protection of the claims.

[0005] The utility model embodiment provides a kind of passive relay protection device, can complete the energy of super capacitor in a short time when the transmission line short circuit being monitored, to ensure that protection switch trips successfully.

[0006] Firstly, the utility model embodiment provides a kind of passive relay protection device, is applied to protection switch, and the protection switch is arranged on transmission line, and the protection device includes:

[0007] Control module;

[0008] A monitoring module, which is electrically connected with the control module and the power transmission line respectively; the monitoring module is used for acquiring power supply parameters of the power transmission line, wherein the power supply parameters include voltage and current values of the power transmission line;

[0009] A driving circuit, which is electrically connected with the control module and the relay of the protection switch respectively; the driving circuit is used for driving the protection switch to perform tripping action;

[0010] A super capacitor, which is electrically connected with the protection switch; the super capacitor is used for providing energy for the protection switch to perform the tripping action;

[0011] An energy supply module, which comprises a CT power taking unit and a conversion unit; the CT power taking unit is provided with a current transformer; an input end of the CT power taking unit is electrically connected with the power transmission line, and an output end of the CT power taking unit is electrically connected with the conversion unit; an output end of the conversion unit is electrically connected with the control module and the super capacitor respectively; the CT power taking unit is used for acquiring electric energy from the power transmission line, and the conversion unit is used for converting the electric energy acquired by the CT power taking unit into working voltage of the passive relay protection device and charging voltage of the super capacitor. According to the passive relay protection device provided by the utility model, the monitoring module can acquire power supply parameters of the power transmission line, the driving circuit can control the protection switch to trip, and the super capacitor can provide tripping energy for the protection switch during the tripping process. The passive relay protection device can acquire electric energy from the power transmission line through the CT power taking unit and convert the electric energy into working power of the device and charging voltage of the super capacitor. According to the technical scheme, since the load current is extremely large when the power transmission line is short-circuited, the efficiency of the CT power taking unit for acquiring electric energy is also improved when the power transmission line is short-circuited. After the super capacitor is discharged to drive the protection switch to trip for the first time, when the power transmission line is faulty again, the super capacitor can be charged in a short time, so that the protection switch can trip in time, and the occurrence of a power accident is prevented.

[0012] According to some embodiments of the first aspect of the utility model, the CT power taking unit comprises three current transformers, three rectifier circuits and a first common-mode filter inductor, a rectifier bridge is arranged in each rectifier circuit; an input end of each current transformer is electrically connected with one phase of the power transmission line respectively, an output end of each current transformer is electrically connected with an input end of one rectifier circuit respectively, output ends of all rectifier circuits are electrically connected with an input end of the first common-mode filter inductor respectively, and an output end of the first common-mode filter inductor is electrically connected with an input end of the conversion unit.

[0013] According to some embodiments of the first aspect of the utility model, the conversion unit includes voltage stabilizing control circuit and boost circuit, the input of voltage stabilizing control circuit is electrically connected with the output of CT electricity taking unit, the output of voltage stabilizing control circuit is electrically connected with the input of boost circuit, the output of boost circuit is electrically connected with super capacitor, voltage stabilizing control circuit is used to carry out voltage stabilizing treatment to the electric energy transmission of CT electricity taking unit to output stable working voltage, boost circuit is used to boost working voltage to the charging voltage of super capacitor.

[0014] According to some embodiments of the first aspect of the utility model, the voltage stabilizing control circuit includes switching power supply chip, first transformer, filter circuit and second common mode filter inductor, the input of first transformer is electrically connected with the output of CT electricity taking unit and switching power supply chip respectively, the output of first transformer is electrically connected with the input of filter circuit, the output of filter circuit is electrically connected with the input of second common mode filter inductor, the output of second common mode filter inductor is electrically connected with boost circuit and control module respectively.

[0015] According to some embodiments of the first aspect of the utility model, the boost circuit includes boost control chip and second transformer, the input of second transformer is electrically connected with the output of voltage stabilizing control circuit and boost control chip respectively, the output of second transformer is electrically connected with super capacitor.

[0016] According to some embodiments of the first aspect of the utility model, the monitoring module includes a plurality of first monitoring units, each first monitoring unit includes monitoring mutual inductor and wave lifting shaping circuit, one monitoring mutual inductor corresponds to one wave lifting shaping circuit, the input of each monitoring mutual inductor is electrically connected with transmission line respectively, the output of each monitoring mutual inductor is electrically connected with the input of corresponding wave lifting shaping circuit, the output of each wave lifting shaping circuit is electrically connected with control module respectively, monitoring mutual inductor is used to obtain power supply parameter, wave lifting shaping circuit is used to AD conversion power supply parameter.

[0017] According to some embodiments of the first aspect of the utility model, the monitoring module further includes power grid frequency extraction circuit, the input of power grid frequency extraction circuit is electrically connected with the output of one first monitoring unit, the output of power grid frequency extraction circuit is electrically connected with control module, power grid frequency extraction circuit is used to obtain the power supply frequency of transmission line.

[0018] According to some embodiments of the first aspect of the utility model, the passive relay protection device further includes LCD display screen and key module, LCD display screen and key module are electrically connected with control module respectively.

[0019] According to some embodiments of the first aspect of the utility model, the passive relay protection device further comprises a 485 communication module, the 485 communication module is electrically connected with the control module, and the 485 communication module is in communication connection with the main station of the power transmission line.

[0020] According to the second aspect of the utility model, the utility model provides a protection switch, and the protection switch comprises the passive relay protection device of the embodiment of the above aspect.

[0021] According to the protection switch provided in the embodiment of the second aspect of the utility model, the protection switch provided with the passive relay protection device of the embodiment of the above aspect has the following beneficial effects: when the power transmission line is short-circuited, the efficiency of obtaining electric energy is also improved, after the protection switch is tripped by the first super capacitor discharging drive, when the power transmission line fails again, the super capacitor can be charged in a short time, so that the protection switch can be tripped in time, and the occurrence of a power accident is prevented.

[0022] Other features and advantages of the utility model will be set forth in the subsequent description, and some of them become apparent from the description, or are understood through implementation of the utility model. The purposes and other advantages of the utility model can be realized and obtained through the structures specially pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings are used to provide a further understanding of the technical scheme of the utility model, and constitute a part of the description, and are used together with the embodiments of the utility model to explain the technical scheme of the utility model, and do not constitute a limitation on the technical scheme of the utility model.

[0024] Figure 1 is a structural block diagram of the passive relay protection device provided in an embodiment of the utility model;

[0025] Figure 2 is a schematic diagram of a driving circuit provided in an embodiment of the utility model;

[0026] Figure 3 is a schematic diagram of a super capacitor provided in an embodiment of the utility model;

[0027] Figure 4 is a schematic diagram of a protection switch provided in an embodiment of the utility model;

[0028] Figure 5 is a schematic diagram of a CT power taking unit provided in an embodiment of the utility model;

[0029] Figure 6 is a schematic diagram of a voltage stabilizing control circuit provided in an embodiment of the utility model;

[0030] Figure 7 is a schematic diagram of a boost circuit provided by an embodiment of the utility model;

[0031] Figure 8 is a schematic diagram of a main control module provided by an embodiment of the utility model;

[0032] Figure 9 is a schematic diagram of a wave lifting shaping circuit provided by an embodiment of the utility model;

[0033] Figure 10 is a schematic diagram of a monitoring mutual inductor provided by an embodiment of the utility model;

[0034] Figure 11 is a schematic diagram of a power grid frequency extraction circuit provided by an embodiment of the utility model;

[0035] Figure 12 is a schematic diagram of an LCD display screen provided by an embodiment of the utility model;

[0036] Figure 13 is a schematic diagram of a key module provided by an embodiment of the utility model;

[0037] Figure 14 is a schematic diagram of a 485 communication module provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0038] The embodiments of the utility model are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the utility model, and cannot be understood as limiting the utility model.

[0039] In the description of the utility model, it is understood that, if there is a description of orientation, for example, the orientation or position relationship of the indications such as up, down, front, back, left and right is based on the orientation or position relationship shown in the drawings, only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as limiting the utility model.

[0040] In the description of the utility model, if there is a description of first, second, only for distinguishing technical features for the purpose, and therefore cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0041] In the description of the utility model, unless otherwise explicitly limited, the words such as setting, installing, connecting should be understood broadly, and the specific meaning of the above words in the utility model can be determined by the person skilled in the art in combination with the specific content of the technical scheme.

[0042] It should be noted that the embodiments of the present application do not limit the improvement of any method, and the function that the device or apparatus can achieve is only based on the hardware architecture of the device or apparatus itself.

[0043] The concepts involved in the utility model are explained as follows:

[0044] CT power taking unit: CT, Current Transformer, Current Transformer, the working principle of Current Transformer is based on electromagnetic induction principle, which can realize the proportional transformation between currents.

[0045] The embodiments of the utility model are further described in combination with the drawings.

[0046] Referring to Figures 1-11 , as shown, Figure 1 It is a structure block diagram of the passive relay protection device provided by an embodiment of the utility model. The embodiment of the utility model provides a kind of passive relay protection device, it is applied to protection switch, protection switch is arranged on transmission line, and protection device includes: control module;Monitoring module, monitoring module is respectively electrically connected with control module and transmission line;Monitoring module is used to obtain the power supply parameter of transmission line, and wherein, power supply parameter includes the voltage value and current value of transmission line;Drive circuit, drive circuit is respectively electrically connected with control module and relay of protection switch;Drive circuit is used to drive protection switch to execute trip action;Super capacitor E2, and it is electrically connected with protection switch;Super capacitor E2 is used to provide energy for protection switch to execute trip action;Energy supply module, including CT power taking unit and conversion unit;The input end of CT power taking unit is electrically connected with transmission line, and the output end of CT power taking unit is electrically connected with conversion unit;The output end of conversion unit is respectively electrically connected with control module and super capacitor E2;CT power taking unit is used to obtain electric energy from transmission line, and conversion unit is used to convert the electric energy obtained by CT power taking unit into the working voltage of passive relay protection device and the energy voltage of super capacitor E2 respectively.

[0047] Specifically, as shown in Figure 8 , control module is used to execute the control logic of passive relay protection device, and control chip STM32F103VCT6 is used in the embodiment of the utility model. As shown in Figures 9-11As shown, the monitoring module is used to realize the monitoring function of the passive relay protection device, that is, to obtain the power supply parameters of the transmission line such as the voltage value and current value of the monitored transmission line, and use this as the basis for the protection switch to protect the transmission line; Among them, since the voltage of the transmission line is usually high, the components used to perform the monitoring function in the monitoring module can be selected through Figure 10 The monitoring transformer CT4 is shown in the figure. The driving circuit is as follows Figure 2 As shown, the protection switch is as Figure 4 As shown, the drive circuit executes the drive control logic through the combination of gate circuits to achieve Figure 4 The control of the relay Rel ay1 of the protection switch. The super capacitor E2 is as follows Figure 5 As shown, through Figure 5 The CE end and Figure 4 The CE terminal in the circuit breaker is electrically connected to provide power to the protection switch. When the relay Rel ay1 of the protection switch is closed, the super capacitor E2 can charge the protection switch so that the protection switch can perform a tripping action. Figure 5 As shown, the CT power taking unit is used to obtain electric energy from the transmission line, so that the passive relay protection device can directly obtain electric energy from the transmission line it monitors, without the need to provide an external power supply for the relay protection device; wherein, the CT power taking unit converts the load current in the transmission line into the working current required by the passive relay protection device in proportion based on the electromagnetic induction principle through the current transformer; it can be understood that the structure of the current transformer is similar to that of the passive relay protection device. Figure 10 The monitoring transformer CT4 in the CT4 is similar, and its specific parameters such as turns ratio can be set according to specific needs. Figure 6 、 Figure 7 As shown, Figure 6 The +5V1 port in Figure 7 The +4.5V port in the CT is electrically connected, and the conversion unit can convert the electric energy obtained by the CT power taking unit into the working voltage required by the control module and other functional modules in the passive relay protection device, as well as the charging voltage required by the supercapacitor E2.

[0048] It can be understood that, since the passive relay protection device directly obtains power from the power transmission line, the efficiency of the passive relay protection device in obtaining power is directly related to the load current in the power transmission line. When the load in the power transmission line is larger, the induced current obtained by the CT power taking unit is larger, the voltage converted by the conversion unit is larger, and the charging efficiency of the super capacitor E2 is also positively related to the charging voltage. Therefore, when the relay protection device performs a tripping action and is closed, if a short-circuit fault occurs again in the power transmission line in a short time, the load current in the power transmission line is extremely large, and the charging efficiency of the super capacitor E2 is also improved, so that the super capacitor E2 is charged to sufficient power for driving the protection switch to trip in a short time. If the charging device of the super capacitor E2 is an external power supply or a battery, the charging speed is constant, and it is possible that the super capacitor E2 cannot be charged after the second short-circuit fault occurs in the power transmission line, resulting in failure of the protection switch to trip and causing a power accident.

[0049] With reference to Figure 5 In some embodiments of the present application, the CT power taking unit comprises three current transformers, three rectifier circuits and a first common-mode filter inductor T1, and a rectifier bridge is arranged in each rectifier circuit. The input end of each current transformer is electrically connected to one phase of the power transmission line, the output end of each current transformer is electrically connected to the input end of one rectifier circuit, the output end of each rectifier circuit is electrically connected to the input end of the first common-mode filter inductor, and the output end of the first common-mode filter inductor is electrically connected to the input end of the conversion unit.

[0050] Specifically, the three-phase power transmission line refers to a power transmission line composed of three independent conductors in a power system, each conductor representing one phase of the three-phase power transmission line, and the three-phase power transmission line is also the most commonly used power transmission method in practical applications. Therefore, in order to obtain power from the three-phase power transmission line, three current transformers are arranged in the CT power taking unit, each current transformer obtains an induced current on one phase of the power transmission line, and the three-phase induced current is transmitted to the rectifier circuit through the port composed of I a1 and I a2, the port composed of I b1 and I b2, and the port composed of Ic1 and Ic2. After rectification and filtering in the rectifier bridges BD1, BD2 and BD3 in the rectifier circuit, the three-phase induced current is integrated into a voltage, and then common-mode interference is suppressed by the common-mode filter inductor T1 to obtain a stable voltage. The voltage is input to the conversion unit for voltage value conversion, so as to obtain the power supply voltage of the control module and the charging voltage of the super capacitor E2.

[0051] With reference toFigures 6-7 In some embodiments of the utility model, the conversion unit includes voltage stabilizing control circuit and boost circuit, the input of voltage stabilizing control circuit is electrically connected with the output of CT electricity taking unit, the output of voltage stabilizing control circuit is electrically connected with the input of boost circuit, the output of boost circuit is electrically connected with super capacitor E2, voltage stabilizing control circuit is used to carry out voltage stabilizing treatment to the electric energy transmitted by CT electricity taking unit to output stable working voltage, boost circuit is used to boost working voltage to the charging voltage of super capacitor E2.

[0052] Specifically, Figure 6 For voltage stabilizing control circuit, Figure 7 For boost circuit. The induced current obtained by CT electricity taking unit cannot be directly used for the function of passive relay protection device and the charging of super capacitor E2, and still needs to be converted into working voltage of passive relay protection device and charging voltage of super capacitor E2 by voltage stabilizing control circuit and boost circuit, wherein voltage stabilizing control circuit is used to carry out voltage transformation, voltage stabilizing and filtering treatment to the power output by electricity taking unit, obtain 5V voltage that can be used by control module and external element of passive relay protection device, and supply power through the voltage. Then 5V voltage is boosted to the charging voltage of super capacitor E2 by boost circuit to charge super capacitor E2.

[0053] Referring to Figure 6 In some embodiments of the utility model, voltage stabilizing control circuit includes switching power supply chip U2, first transformer T2, filter circuit and second common mode filter inductor T3, the input of first transformer T2 is electrically connected with the output of CT electricity taking unit and switching power supply chip U2 respectively, the output of first transformer T2 is electrically connected with the input of filter circuit, the output of filter circuit is electrically connected with the input of second common mode filter inductor T3, and the output of second common mode filter inductor T3 is electrically connected with boost circuit and control module respectively.

[0054] Specifically, as Figure 6 Indicated in the utility model embodiment, switching power supply chip U2 is used to control voltage stabilizing, chopping and voltage reduction are carried out through switching transformer T2, 5V stable voltage is obtained by adding feedback control through filter circuit composed of E5, L2 and E6, and finally the obtained 5V voltage still needs to be inhibited common mode interference through common mode filter inductor T3 to obtain stable 5V working voltage.

[0055] Referring to Figure 7 In some embodiments of the utility model, boost circuit includes boost control chip U3 and second transformer T4, the input of second transformer T4 is electrically connected with the output of voltage stabilizing control circuit and boost control chip U3 respectively, and the output of second transformer T4 is electrically connected with super capacitor E2.

[0056] Specifically, as shown in Figure 7 In some embodiments of the utility model, the input voltage of the voltage boosting circuit (+4.5V port) can be provided by the battery of the voltage stabilizing control circuit and the passive relay protection device. It can be understood that, since the voltage output by the voltage stabilizing control circuit is derived from the induced current of the power transmission line, the voltage is directly proportional to the induced current of the power transmission line, and the size can be limited by the switching power supply chip U2 or not limited by the switching power supply chip U2.

[0057] Referring to Figures 9-11 In some embodiments of the utility model, the monitoring module includes a plurality of first monitoring units, each first monitoring unit includes a monitoring mutual inductor and a wave lifting shaping circuit, one monitoring mutual inductor corresponds to one wave lifting shaping circuit; the input end of each monitoring mutual inductor is electrically connected with the power transmission line respectively, the output end of each monitoring mutual inductor is electrically connected with the input end of the corresponding wave lifting shaping circuit, and the output end of each wave lifting shaping circuit is electrically connected with the control module respectively; the monitoring mutual inductor is used for obtaining power supply parameters, and the wave lifting shaping circuit is used for AD converting power supply parameters.

[0058] Specifically, for monitoring the power supply parameters of the power transmission line to serve as the basis for the protection switch to perform tripping action, one embodiment of the utility model is provided with a plurality of first monitoring units, each first monitoring unit includes Figure 9 The wave lifting shaping circuit as shown in Figure 10 The monitoring mutual inductor CT4 based on the principle of electromagnetic induction obtains the induced current from the power transmission line, transmits to the AIN end of the wave lifting shaping circuit, processes the induced current through the wave lifting shaping circuit, and transmits to the control module from the AD end of the wave lifting shaping circuit to obtain the power supply parameters of the power transmission line. The utility model embodiment provides 4 first monitoring units, which can monitor 4 types of power supply parameters in the power transmission line.

[0059] Referring to Figure 11 In some embodiments of the utility model, the monitoring module further includes a power grid frequency extraction circuit, the input end of the power grid frequency extraction circuit is electrically connected with the output end of a first monitoring unit, and the output end of the power grid frequency extraction circuit is electrically connected with the control module; the power grid frequency extraction circuit is used for obtaining the power supply frequency of the power transmission line.

[0060] Specifically, as shown in Figure 11 As shown in Figure 11 The in-phase input end AIN of U9 in Figure 10The AIN electrical connection of the intermediate wave shaping circuit enables the first monitoring unit to obtain the power supply frequency of the transmission line.

[0061] In some embodiments of the present invention, the passive relay protection device further includes an LCD display screen and a key module, and the LCD display screen and the key module are electrically connected to the control module respectively.

[0062] Specifically, the LCD display screen is Figure 12 As shown, the LCD display is used to display the power supply parameters of the transmission line; the circuit structure of the button module is as shown Figure 13 As shown, the button module can switch the display content of the LCD display screen so that maintenance personnel can intuitively obtain the power supply parameters of the transmission line.

[0063] In some embodiments of the present invention, the passive relay protection device further includes a 485 communication module, which is electrically connected to the control module; and the 485 communication module is communicatively connected to a master station of the transmission line.

[0064] Specifically, the 486 communication module is as follows Figure 14 As shown, the input terminals RXD3 and TXD3 of the 485 communication module are electrically connected to the control module, and the output terminals RS485A and RS485B of the 485 communication module are communicatively connected to the master station of the transmission line. Specifically, the communication connection with the master station can be achieved through a twisted pair cable.

[0065] In a second aspect, an embodiment of the present invention provides a protection switch, characterized in that the protection switch includes the passive relay protection device of the embodiment of the above aspect.

[0066] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above implementation. Technical personnel familiar with the field can also make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A passive overcurrent protection device, characterized in that The application is applied to a protection switch arranged on a power transmission line, and the protection device comprises: a control module; a monitoring module electrically connected with the control module and the power transmission line respectively; the monitoring module is used to acquire power supply parameters of the power transmission line, wherein the power supply parameters comprise voltage and current values of the power transmission line; a driving circuit electrically connected with the control module and a relay of the protection switch respectively; the driving circuit is used to drive the protection switch to perform a tripping action; a super capacitor electrically connected with the protection switch; the super capacitor is used to provide energy for the protection switch to perform the tripping action; an energy supply module comprising a CT power taking unit and a conversion unit; the CT power taking unit is provided with a current transformer; an input end of the CT power taking unit is electrically connected with the power transmission line, and an output end of the CT power taking unit is electrically connected with the conversion unit; an output end of the conversion unit is electrically connected with the control module and the super capacitor respectively; the CT power taking unit is used to acquire electric energy from the power transmission line, and the conversion unit is used to convert the electric energy acquired by the CT power taking unit into working voltage of the passive relay protection device and charging voltage of the super capacitor respectively.

2. The passive relaying protection device according to claim 1, characterized in that, The CT power taking unit comprises three current transformers, three rectifier circuits and a first common mode filter inductor; each of the rectifier circuits is provided with a rectifier bridge; an input end of each current transformer is electrically connected with one phase of the power transmission line respectively, an output end of each current transformer is electrically connected with an input end of one rectifier circuit respectively, output ends of all the rectifier circuits are electrically connected with an input end of the first common mode filter inductor respectively, and an output end of the first common mode filter inductor is electrically connected with an input end of the conversion unit.

3. The passive relaying protection device according to claim 1, characterized in that, The conversion unit comprises a voltage stabilizing control circuit and a boost circuit; an input end of the voltage stabilizing control circuit is electrically connected with an output end of the CT power taking unit, an output end of the voltage stabilizing control circuit is electrically connected with an input end of the boost circuit, and an output end of the boost circuit is electrically connected with the super capacitor; The voltage stabilizing control circuit is used to perform voltage stabilizing treatment on the electric energy transmitted by the CT power taking unit to output stable working voltage; the boost circuit is used to boost the working voltage to charging voltage of the super capacitor.

4. The passive relaying protection device according to claim 3, characterized in that, The voltage stabilizing control circuit comprises a switching power supply chip, a first transformer, a filter circuit and a second common mode filter inductor; an input end of the first transformer is electrically connected with an output end of the CT power taking unit and the switching power supply chip respectively, an output end of the first transformer is electrically connected with an input end of the filter circuit, an output end of the filter circuit is electrically connected with an input end of the second common mode filter inductor, and an output end of the second common mode filter inductor is electrically connected with the boost circuit and the control module respectively.

5. The passive relaying protection device according to claim 3, characterized in that, The boost circuit comprises a boost control chip and a second transformer; an input end of the second transformer is electrically connected with an output end of the voltage stabilizing control circuit and the boost control chip respectively, and an output end of the second transformer is electrically connected with the super capacitor.

6. The passive relaying protection device of claim 1, wherein, The monitoring module comprises a plurality of first monitoring units, each of which comprises a monitoring mutual inductor and a wave lifting shaping circuit, one monitoring mutual inductor corresponding to one wave lifting shaping circuit; the input end of each monitoring mutual inductor is electrically connected with the power transmission line, the output end of each monitoring mutual inductor is electrically connected with the input end of the corresponding wave lifting shaping circuit, and the output end of each wave lifting shaping circuit is electrically connected with the control module; the monitoring mutual inductor is used to acquire the power supply parameter, and the wave lifting shaping circuit is used to AD convert the power supply parameter.

7. The passive relaying protection device according to claim 6, characterized in that, The monitoring module further comprises a power grid frequency extraction circuit, the input end of the power grid frequency extraction circuit is electrically connected with the output end of one first monitoring unit, and the output end of the power grid frequency extraction circuit is electrically connected with the control module; the power grid frequency extraction circuit is used to acquire the power supply frequency of the power transmission line.

8. The passive relaying protection device of claim 1, wherein, The passive relaying protection device further comprises an LCD display screen and a key module, and the LCD display screen and the key module are electrically connected with the control module respectively.

9. The passive relaying protection device of claim 1, wherein, The passive relaying protection device further comprises a 485 communication module, the 485 communication module is electrically connected with the control module, and the 485 communication module is in communication connection with the main station of the power transmission line.

10. A protective switch, characterized by The protection switch comprises the passive relaying protection device according to any one of claims 1 to 9.

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