CN203673002U - Direct current system earth fault searching device - Google Patents

Abstract

The utility model provides a DC system grounding fault finding device, comprising: a DC insulation monitoring relay for collecting positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance and negative-to-ground resistance of a DC system bus bar; The Hall current sensor for the current signal on the DC feeder branch circuit; the operational amplifier connected with the Hall current sensor to convert the current signal into a voltage signal; the A/D converter connected with the operational amplifier to convert the voltage signal into a digital signal ; respectively connected to the DC insulation monitoring device and the A/D converter, and calculate the first current value according to the positive-to-ground voltage, a set of values of positive-to-ground resistance or the set of negative-to-ground voltage and negative-to-ground resistance , calculate the second current value according to the digital signal, and when the first current value is equal to the second current value, output the single-chip microcomputer of fault information. Compared with the existing equipment, the equipment of the present application does not add an AC signal when finding the ground fault, thus ensuring the safety of the electric equipment.

Description

A DC system ground fault finding device

technical field

The utility model relates to the technical field of power system safety management, in particular to a DC system grounding fault finding device.

Background technique

The DC power supply system of the substation is designed to provide uninterrupted power for various equipment in the substation. The system is an ungrounded system with long-term electrified operation, but due to dust or insulation faults, the system ground fault occurs, which will lead to malfunction or refusal of relay protection. The DC power supply system has many branch circuits, and when a ground fault occurs, it is necessary to accurately find the fault line and level the operating point, and deal with the ground fault.

The existing fault finding equipment checks the fault line by adding AC signal to the DC power system. The AC signal will cause certain damage to the DC power battery, relay protection equipment and other power equipment, and even lead to a safety accident of the power grid in severe cases.

Utility model content

In view of this, the utility model provides a DC system grounding fault finding device to solve the problem that the existing fault finding device will cause certain damage to power equipment such as DC power supply batteries and relay protection devices during operation, and in serious cases will cause power grid failure. safety incidents. The technical scheme of the utility model is as follows:

A DC system ground fault finding device, comprising:

A DC insulation monitoring relay that collects the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance and negative-to-ground resistance of the DC system busbar;

A Hall current sensor for collecting current signals on the DC feeder branch loop of the DC system;

An operational amplifier that is connected to the Hall current sensor and converts the current signal into a voltage signal;

An A/D converter that is connected to the operational amplifier and converts the voltage signal into a digital signal;

respectively connected to the DC insulation monitoring device and the A/D converter, and calculate the first A current value, calculating a second current value based on the digital signal, when the first current value is equal to the second current value, the single-chip microcomputer that outputs fault information

Preferably, it also includes: a display connected to the single-chip microcomputer to receive and display the fault information.

Preferably, it also includes: respectively connecting with the DC insulation monitoring relay, Hall current sensor, operational amplifier, A/D converter, single-chip microcomputer, and display, and connecting to the DC insulation monitoring relay, Hall current sensor, operational amplifier, A/D converter, single-chip microcomputer, and display provide power supply for power supply.

Preferably, the DC insulation monitoring relay is connected to the single-chip microcomputer through a wireless communication module, and the wireless communication module includes:

A wireless transmitting sub-module connected to the DC monitoring relay and sending the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance, and negative-to-ground resistance collected by the DC monitoring relay;

Connect with the wireless transmitting sub-module and the single-chip microcomputer respectively, receive the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance and negative-to-ground resistance sent by the wireless transmitting sub-module and transmit them to the single-chip microcomputer The wireless receiving sub-module.

Preferably, the DC insulation monitoring relay is connected to the single-chip microcomputer through a wired communication module.

Preferably, when the first current value is equal to the second current value, the single-chip microcomputer outputs an alarm signal, and the device further includes:

The alarm device is connected with the single-chip microcomputer, receives the alarm signal output by the single-chip microcomputer, and performs alarm according to the alarm signal.

From the above technical solutions, it can be seen that the utility model provides a DC system grounding fault finding device, including: collecting the positive-to-ground voltage, the negative-to-ground voltage, the positive-to-ground resistance and the negative-to-ground resistance of the DC system bus. monitoring relay; collecting the Hall current sensor of the current signal on the DC DC feeder branch circuit of the DC system; being connected with the Hall current sensor, and converting the current signal into a voltage signal; The amplifier is connected to an A/D converter that converts the voltage signal into a digital signal; it is connected to the DC insulation monitoring device and the A/D converter respectively, and according to the positive-to-ground voltage and the positive-to-ground resistance A set value or the set value of the negative-to-ground voltage and negative-to-ground resistance calculates the first current value, and calculates the second current value according to the digital signal, when the first current value is equal to the second current value , The single-chip microcomputer that outputs the fault signal. Compared with the existing fault finding equipment that adds AC signals when searching for grounding faults, the device provided by the utility model does not add the AC signals. The Hall current sensor detects the current signal on the feeder circuit of the DC system, and the single-chip microcomputer will When the current signal is equal to the ground current of the DC system bus detected by the DC insulation monitoring relay, it means that there is a ground fault point in the feeder circuit, thereby solving the problem of adding an AC signal to the DC system in the prior art. The problem of damage caused by the power equipment in the system ensures the safety of the power equipment in the process of finding the ground fault in the DC system.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description It is only an embodiment of the utility model, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is a structural schematic diagram of Embodiment 1 of a DC system grounding fault finding device provided by the utility model;

Fig. 2 is a structural schematic diagram of Embodiment 2 of a DC system grounding fault finding device provided by the utility model;

Fig. 3 is a partial structural diagram of Embodiment 3 of a DC system grounding fault finding device provided by the utility model;

Fig. 4 is a structural schematic diagram of Embodiment 4 of a DC system ground fault finding device provided by the utility model.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Please refer to FIG. 1 , which shows a schematic structural diagram of Embodiment 1 of a DC system ground fault finding device provided by the present application. This embodiment may include: a DC insulation monitoring relay 101 , a Hall current sensor 102 , an operational amplifier 103 , an A/D converter 104 , and a single-chip microcomputer 105 . in:

The DC insulation monitoring relay 101 is respectively connected to the positive pole and the negative pole of the DC system bus, and the DC insulation monitoring relay 101 is provided with a bridge circuit. A resistor with a preset value such as 60K can calculate the positive pole-to-ground voltage and the negative pole-to-ground voltage from the current output from the middle point of the bridge circuit. By using the DC insulation monitoring relay 101 connected to the busbar of the DC system, the positive pole-to-ground resistance and the negative pole-to-ground resistance of the DC system can be measured. The test principle is the positive-to-ground resistance and negative-to-ground resistance calculated by the DC insulation monitoring relay, using the corresponding calculation method of the sensor voltage.

The Hall current sensor 102 calculates the current intensity by collecting the magnetic field generated by the current. The specific process is based on the magnetic balance Hall principle, that is, the closed-loop principle. When the magnetic flux generated by the primary current IP is concentrated in the magnetic circuit through a high-quality magnetic core, the Hall element is fixed in the air gap to detect the magnetic flux. The multi-turn coil on the magnetic core outputs a reverse compensation current, which is used to offset the magnetic flux generated by the primary side IP, so that the magnetic flux in the magnetic circuit is always kept at zero. After being processed by a special circuit, the output terminal of the sensor can output a current change that accurately reflects the current of the primary side.

The Hall current sensor 102 collects positive and negative currents on the DC feeder branch circuit of the DC system. The current value sensed by the Hall current sensor is also the current value of the leakage current.

The operational amplifier 103 is connected to the Hall current sensor 102, and converts the current signal collected by the Hall current sensor 102 into a 0-5V standard voltage signal.

The A/D converter 104 is connected to the operational amplifier 103 to convert the 0-5V voltage signal into a digital signal.

The single-chip microcomputer 105 is connected to the DC insulation monitoring relay 101 and receives the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance and negative-to-ground resistance collected by the DC insulation monitoring device 101 . Using the current calculation formula, current=voltage÷resistance, the positive current value of the DC system is calculated based on the positive-to-ground voltage÷positive-to-ground resistance, or the negative current value of the DC system is calculated based on the negative-to-ground voltage÷negative-to-ground resistance.

The single-chip microcomputer 105 is connected with the A/D converter 104, and receives the digital signal converted by the A/D converter 104. The digital signal is the DC feeder branch of the DC system collected by the Hall current sensor 102. The current signal on the loop is converted, and the current value of the current signal can be calculated according to the digital signal. When the current value of the current signal is equal to the positive pole current value of the DC system or the negative pole current value of the DC system, it means that there is a leakage circuit in the branch circuit of the DC feeder detected by the Hall current sensor 102, that is, the The branch circuit of the DC feeder is grounded, and the fault point can be determined as the branch circuit of the DC feeder. The single-chip microcomputer has a numerical calculation function, and the single-chip microcomputer 105 in this embodiment uses this function of the single-chip microcomputer.

It should be noted that the positive current value of the DC system or the negative current value of the DC system calculated by the single-chip microcomputer 105 is a first current value, and the calculated current value of the current signal is a second current value.

When the first current value is equal to the second current value, the single-chip microcomputer 105 outputs fault information. Wherein, the fault information includes, but is not limited to, the positive pole-to-ground voltage, the negative pole-to-ground voltage, the positive pole-to-ground resistance, the negative pole-to-ground resistance of the DC system, and the current signal is leakage current.

It can be seen from the above technical solutions that the DC system ground fault finding equipment provided in this embodiment uses a single-chip microcomputer to compare the current of the DC system feeder branch collected by the Hall current sensor with the current collected by the DC insulation monitoring relay. When the magnitudes of the positive pole current value or the negative pole current value of the DC system bus are equal, it indicates that there is a ground fault in the DC feeder branch circuit. The equipment provided in this embodiment does not inject AC signals into the DC system, and thus does not cause damage to the electrical equipment of the DC system during the ground fault detection process, thereby providing safety in the detection process.

In the first embodiment, the single-chip computer judges whether the DC feeder branch circuit of the DC system detected by the Hall current sensor is grounded through calculation, and outputs fault information, which can be displayed on the display for relevant personnel Conduct further analysis of ground fault information. Please refer to FIG. 2 , which shows a schematic structural diagram of Embodiment 2 of a DC system ground fault finding device provided by the present application. In addition to 101 to 105 in Embodiment 1, it may also include: a display 206 and a power supply 207 . in:

The display 206 is connected to the single-chip microcomputer 105, receives the fault information and displays it, and the display form is not limited, and can be graphics and/or numbers. Wherein, the current signal in the fault information, that is, the leakage current, may be displayed in the form of a waveform diagram. Relevant personnel can use the waveform to judge the grounding degree of the branch circuit of the detected DC feeder.

The power supply 207 can be a multifunctional power supply, which is connected to the DC insulation monitoring relay 101, the Hall current sensor 102, the operational amplifier 103, the A/D converter 104, the single-chip microcomputer 105, and the display 106 respectively, according to the 101 The respective working voltages to 106 provide power to the DC insulation monitoring relay 101 , Hall current sensor 102 , operational amplifier 103 , A/D converter 104 , single-chip microcomputer 105 , and display 206 .

On the basis of Embodiment 1, the connection mode between the single-chip microcomputer 105 and the DC insulation monitoring relay 101 can be a wired connection, or a wireless communication module can be used for wireless connection. When the connection mode is wireless connection, please refer to Fig. 3, which shows a partial structural diagram of Embodiment 3 of the DC system ground fault finding device provided by the utility model, and the wireless communication module includes a wireless transmitter The submodule 301 and the wireless receiving submodule 302. in:

The wireless transmitting sub-module 301 is connected to the DC insulation monitoring relay 101, and transmits the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance, and negative-to-ground resistance collected by the DC insulation monitoring relay 101. send.

The wireless receiving sub-module 302 is connected to the wireless transmitting sub-module 301 and the single-chip microcomputer 105, and receives the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance and negative voltage transmitted by the wireless transmitting sub-module 301. resistance to ground, and transmit the received information to the single-chip microcomputer 105 .

The wireless receiving submodule 302 needs to perform a communication connection before receiving the information sent by the wireless transmitting submodule 301. The connection process is that the wireless transmitting submodule 301 sends a handshake signal to the outside. When the wireless receiving submodule 302 receives When the received signal is a 50HZ handshake signal, the information sent by the wireless transmitting sub-module 301 is received, including the positive-to-ground voltage, negative-to-ground voltage, positive-to-ground resistance and negative-to-ground resistance. Wherein, the transmitting frequency of the wireless transmitting sub-module 301 may be 11200HZ.

It can be seen from the above technical solutions that the DC insulation monitoring relay and the single-chip microcomputer in the DC system ground fault finding equipment provided by this embodiment are connected through a wireless communication module, which saves the connecting wire and has the advantage of movable detection. Effect.

Please refer to FIG. 4 , which shows a schematic structural diagram of Embodiment 4 of a DC system ground fault finding device provided by the present invention. On the basis of Embodiment 2, this embodiment further includes: an alarm 408 . in:

The alarm 408 is connected to the single-chip microcomputer 405, and can also output an alarm signal when the first current signal calculated by the single-chip microcomputer 405 is equal to the second current signal. When the alarm device 408 receives the alarm signal, it will alarm. The alarm form may be buzzing and/or flashing. Of course, the power supply 408 is respectively connected to the 401 to 407 to provide power to the 401 to 407 .

From the above technical solutions, it can be seen that the DC system ground fault finding device provided in this embodiment can, when there is a ground fault in the DC feeder branch circuit of the DC system, the alarm device will give an alarm in the form of sound and/or light to further remind the ground fault the presence of information.

It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. For the same and similar parts in each embodiment, refer to each other, that is, Can. As for the system embodiment, because it is basically similar to the method embodiment, the description is relatively simple, and for the related parts, please refer to the part of the description of the method embodiment.

Finally, it should also be noted that in this text, relational terms such as first and second etc. are only used to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations, any such actual relationship or order exists. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The above is a detailed introduction of a DC system grounding fault finding device provided by the present invention. In this paper, specific examples are used to illustrate the principle and implementation of the present application. The description of the above embodiments is only used to help understand the present application. method and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation and scope of application. In summary, the content of this specification should not be understood as Limitations on this Application.

Claims (6)

1. DC system earth fault is searched an equipment, it is characterized in that, comprising:

Gather the DC insulation monitoring relay of the positive voltage-to-ground of straight-flow system bus, negative voltage-to-ground, positive resistance to earth and negative resistance to earth;

Gather the Hall current sensor of the current signal on the DC feeder duplexure of described straight-flow system;

Be connected with described Hall current sensor, described current signal converted to the operational amplifier of voltage signal;

Be connected with described operational amplifier, described voltage signal converted to the A/D converter of digital signal;

Be connected with described direct-current insulation monitoring device, described A/D converter respectively, calculate the first current value according to described positive voltage-to-ground, positive resistance to earth one class value or described negative voltage-to-ground, negative resistance to earth one class value, calculate the second current value according to described digital signal, in the time that described the first current value equates with described the second current value, the single-chip microcomputer of output failure message.

2. equipment according to claim 1, is characterized in that, also comprises:

Be connected with described single-chip microcomputer, the display that receives described failure message and show.

3. equipment according to claim 2, is characterized in that, also comprises:

Be connected with described DC insulation monitoring relay, Hall current sensor, operational amplifier, A/D converter, single-chip microcomputer, display respectively, the power supply of power supply is provided to described DC insulation monitoring relay, Hall current sensor, operational amplifier, A/D converter, single-chip microcomputer, display.

4. equipment according to claim 1, is characterized in that, described DC insulation monitoring relay is connected by wireless communication module with described single-chip microcomputer, and described wireless communication module comprises:

Be connected with described direct current monitoring relay, the wireless transmit submodule that the described positive voltage-to-ground that described direct current monitoring relay is gathered, negative voltage-to-ground, positive resistance to earth and negative resistance to earth outwards send;

Be connected with described wireless transmit submodule, described single-chip microcomputer respectively, receive described positive voltage-to-ground, negative voltage-to-ground, positive resistance to earth and the negative resistance to earth that described wireless transmit submodule sends the wireless receiving submodule that transfers to described single-chip microcomputer.

5. equipment according to claim 1, is characterized in that, described DC insulation monitoring relay is connected by wire communication module with described single-chip microcomputer.

6. according to the equipment described in claim 1 to 5 any one, it is characterized in that, in the time that described the first current value equates with described the second current value, described single-chip microcomputer output alarm signal, described equipment also comprises:

Be connected with described single-chip microcomputer, receive the alerting signal of described single-chip microcomputer output, the alarm of reporting to the police according to described alerting signal.

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