CN203658521U - Mobile insulation supervision instrument of transformer station DC system - Google Patents

Abstract

The utility model discloses a mobile insulation monitoring instrument for a DC system of a substation, which includes a monitoring host, a data acquisition device and a mobile sensor. The monitoring host includes a bridge circuit, a protection circuit, an ultra-low frequency signal generator, a module Digital conversion circuit, microprocessor, alarm device, display device, communication module, photoelectric isolation device. The data acquisition device includes more than one group of connected analog selection switches, amplifiers, band-pass filters, phase comparators, filters, analog-to-digital conversion circuits and microprocessors. The mobile insulation monitor of the DC system of the substation of the utility model has the characteristics of a mobile type, and can detect multiple circuits at the same time, and the automation program is highly adaptable, and can perform supervisory inspection on the original DC system bridge of the substation. However, the impedance of the original bridge is detected, and the original circuit is set through the setting menu.

Description

Substation DC system mobile insulation monitor

technical field

The utility model relates to an insulation monitoring device, in particular to a mobile insulation monitoring device for a DC system of a substation.

Background technique

At present, the domestic DC power insulation monitoring devices are all fixed, and can only be installed in a certain substation to work. If the insulation monitoring device fails, during the troubleshooting of the monitoring device, the DC power supply of the substation loses the insulation monitoring device at this time. The safe operation of DC power supply brings hidden dangers. In order to ensure the safe operation of the power system, a set of general-purpose DC insulation monitoring equipment must be replaced in time to monitor the DC system insulation.

Utility model content

The purpose of this utility model is to overcome the deficiencies of the prior art, and to provide a mobile insulation system for substation direct current systems that is suitable for various direct current systems and can be put into use in an emergency, thereby ensuring the normal operation of the direct current system in a timely and effective manner. Monitor.

A mobile insulation monitoring instrument for substation DC system, including a monitoring host, a data acquisition device and a mobile sensor, the monitoring host includes a bridge circuit, a protection circuit, an ultra-low frequency signal generator, an analog-to-digital conversion circuit, a micro A processor, an alarm device, a display device, a communication module, and a photoelectric isolation device, the bridge circuit includes a balanced bridge detection circuit and an unbalanced bridge detection circuit; the protection circuit is connected to the microprocessor by controlling the ultra-low frequency signal generator, The bridge circuit is connected to the microprocessor through analog-to-digital conversion, and the microprocessor is also connected to the communication module, photoelectric isolation device, alarm device and display device, and the photoelectric isolation device is connected to the data acquisition device through the serial port;

The data acquisition device includes more than one group of connected analog selector switches, amplifiers, bandpass filters, phase comparators, filters, analog-to-digital conversion circuits and microprocessors, and the analog selector switches are passed through mobile The sensor obtains the induced current signal, and the monitoring host controls the operation of the ultra-low frequency signal generator and simultaneously outputs a synchronous signal to the phase comparator of the data acquisition device. After the monitoring host monitors that the bus bar is grounded, the host injects the ultra-low frequency signal source into the DC system, Data acquisition sends the induced current sent by the mobile sensor to the microprocessor for processing through the analog selection switch, amplifier, band-pass filter, phase comparator, filter, and analog-to-digital conversion circuit, and then through the serial circuit of the microprocessor. The interface is sent to the monitoring host;

The mobile sensor is stuck on each branch circuit of the busbar. If there is a resistance grounding on the branch circuit, the sensor installed on the branch will generate an induced current. The magnitude of the induced current is proportional to the resistance of the branch grounding resistance. inverse ratio.

The mobile insulation monitor of the substation DC system of the utility model can realize the grounding of the DC system lines, the branch grounding search, the overvoltage and undervoltage detection, and provide alarm information output and display device display according to the detection results. At the same time, the data It is transmitted to the upper computer through the communication interface circuit. Since the utility model is equipped with two electric bridges, it can be used in different DC systems of substations. Since the phase comparator is used in the data acquisition device, it can eliminate the error on the branch circuit. The influence of capacitance to ground on the accuracy of measuring ground resistance can also overcome the interference of asynchronous AC signals on the bus. Due to the use of mobile sensors, multiple substations only need to use a set of mobile insulation detector equipment, which can save a lot of equipment costs.

The setting of the balanced bridge circuit and the unbalanced bridge circuit in the bridge circuit is as follows: according to the principle of the original DC system power monitor on site, when the circuit of the original substation is a balanced circuit, if the equipment After a fault occurs, the bridge cannot be withdrawn. When the mobile insulation monitor of the DC system of the substation is used again, when the unbalanced circuit is used for monitoring, the correction value of the setting device parameter is set to 0 and then put into measurement, and the balance on the original equipment is measured. For the resistance value on the bridge, correct the measured resistance value as a correction value, and then select the balance circuit for measurement. When the monitor calculates the grounding resistance, the CPU will change the coefficient in the original calculation formula according to the set correction value , which can eliminate the influence of the original balanced circuit, so that the re-invested equipment can be monitored accurately without false alarms; If the devices working on the balanced circuit are put into operation at the same time, if the false detection or false alarm is caused, it is necessary to turn off the power of the faulty device first, and then use the above-mentioned unbalanced bridge method to measure and correct the data, and then put it into the unbalanced circuit operation. Due to the unbalanced circuit monitoring, the calculation formula is more complicated, and the calculation accuracy is poor when the grounding resistance is large, so the experimental calibration method is adopted, the data list obtained from the experiment is stored in the register, and then the table is checked according to the original set correction value Calculation processing eliminates the impact of the original balance circuit on the accuracy of the measurement, so that the re-invested equipment can be monitored accurately without false alarms.

The mobile sensor is a caliper-type mobile sensor, and the caliper is made of strong magnetic material and adopts electromagnetic shielding.

The caliper is configured with caliper-type detection probes of different sizes and shapes.

The amplifiers in the data acquisition device are operational amplifiers and data amplifiers with low noise, low drift, low power consumption and high isolation.

In summary, the utility model has the following advantages compared with the prior art:

The mobile insulation monitor of the DC system of the substation of the utility model has the characteristics of a mobile type, and can detect multiple circuits at the same time, and the automation program is highly adaptable, and can perform supervisory inspection on the original DC system bridge of the substation. However, the impedance of the original bridge is detected, the original circuit is set through the setting menu, and the balance bridge of the original system is detected during normal operation of the shield, and the equipment is used to restore the normal operation interface. This set of equipment can be used as multiple Backup equipment in substations. The application of the mobile insulation monitor for the DC system of the substation of the utility model improves the safety and reliability of the power grid operation, and the economic and social benefits are obvious: multiple substations only need to use a set of mobile insulation detector equipment, which can save a lot Equipment cost; due to the high degree of automation and easy movement of the equipment, the efficiency of the substation to eliminate the insulation fault of the DC system is greatly improved, and the power loss caused by the elimination of the insulation fault is greatly saved. At the same time, it is also effective to prevent substation operators (especially unattended stations) from having to go to the station for regular inspections during the period when the monitoring device is damaged, saving manpower input. the

Description of drawings

Figure 1 is the circuit composition of the utility model substation DC system mobile insulation monitor.

Detailed ways

Below in conjunction with embodiment the utility model is described in more detail.

Example 1

A mobile insulation monitoring instrument for substation DC system, including a monitoring host, a data acquisition device and a mobile sensor, the monitoring host includes a bridge circuit, a protection circuit, an ultra-low frequency signal generator, an analog-to-digital conversion circuit, a micro A processor, an alarm device, a display device, a communication module, and a photoelectric isolation device. The protection circuit realizes busbar monitoring. After the bridge circuit detects that the busbar is grounded, the protection circuit controls the operation of the ultra-low frequency signal generator and synchronously outputs a synchronous signal to the data The acquisition device, the bridge circuit includes a balanced bridge detection circuit and an unbalanced bridge detection circuit; the protection circuit is connected to the microprocessor by triggering and controlling the ultra-low frequency signal generator, and the bridge circuit is connected to the microprocessor through analog-to-digital conversion , the microprocessor is also connected to the communication module, photoelectric isolation device, alarm device and display device, and the photoelectric isolation device is connected to the data acquisition device through the serial port;

The data acquisition device includes more than one group of connected analog selector switches, amplifiers, bandpass filters, phase comparators, filters, analog-to-digital conversion circuits and microprocessors, and the analog selector switches are passed through mobile The sensor obtains the induced current signal, and the monitoring host controls the operation of the ultra-low frequency signal generator and simultaneously outputs a synchronous signal to the phase comparator of the data acquisition device. After the monitoring host monitors that the bus bar is grounded, the host injects the ultra-low frequency signal source into the DC system, Data acquisition sends the induced current sent by the mobile sensor to the microprocessor for processing through the analog selection switch, amplifier, band-pass filter, phase comparator, filter, and analog-to-digital conversion circuit, and then through the serial circuit of the microprocessor. The interface is sent to the monitoring host;

The mobile sensor is stuck on each branch circuit of the busbar. If there is a resistance grounding on the branch circuit, the sensor installed on the branch will generate an induced current. The magnitude of the induced current is proportional to the resistance of the branch grounding resistance. inverse ratio.

The setting of the balanced bridge circuit and the unbalanced bridge circuit in the bridge circuit is as follows: according to the principle of the original DC system power monitor on site, when the circuit of the original substation is a balanced circuit, if the equipment After a fault occurs, the bridge cannot be withdrawn. When the mobile insulation monitor of the DC system of the substation is used again, when the unbalanced circuit is used for monitoring, the correction value of the setting device parameter is set to 0 and then put into measurement, and the balance on the original equipment is measured. For the resistance value on the bridge, correct the measured resistance value as a correction value, and then select the balance circuit for measurement. When the monitor calculates the grounding resistance, the CPU will change the coefficient in the original calculation formula according to the set correction value , which can eliminate the influence of the original balanced circuit, so that the re-invested equipment can be monitored accurately without false alarms; If the devices working on the balanced circuit are put into operation at the same time, if the false detection or false alarm is caused, it is necessary to turn off the power of the faulty device first, and then use the above-mentioned unbalanced bridge method to measure and correct the data, and then put it into the unbalanced circuit operation. Due to the unbalanced circuit monitoring, the calculation formula is more complicated, and the calculation accuracy is poor when the grounding resistance is large, so the experimental calibration method is adopted, the data list obtained from the experiment is stored in the register, and then the table is checked according to the original set correction value Calculation processing eliminates the impact of the original balance circuit on the accuracy of the measurement, so that the re-invested equipment can be monitored accurately without false alarms. The mobile sensor is a caliper-type mobile sensor, and the caliper is made of strong magnetic material and adopts electromagnetic shielding. The caliper is configured with caliper-type detection probes of different sizes and shapes.

Described data acquisition device adopts operational amplifier and data amplifier with low noise, low drift, low power consumption, high isolation, high-precision A/D converter, and single-chip microprocessor with stronger function to form a narrow-band filter , phase comparator, fine-to-coarse signal converter, and information and data processing, automatic correction of measured values, by designing new lines with strong anti-interference ability and high sensitivity and new signal processing methods, the sensitivity and anti-corrosion of the detector can be improved. Interference ability. The circuit structure is as shown in Figure 5. If there is a resistance grounding on the branch circuit, the sensor installed on the branch will generate an induced current, and the magnitude of the induced current is inversely proportional to the resistance of the branch grounding resistance. The induced current signal is sent to the CPU for data processing through the analog selection switch, amplification, band-pass filter, phase comparison, filter, A/D conversion, and then sent to the host through the RS485 interface. On the one hand, the host controls the signal acquisition module to collect the sensor signals of each branch in an orderly manner, and on the other hand, it receives the data sent by the signal acquisition module. The phase comparator in the signal acquisition module is used to eliminate the influence of the ground capacitance on the branch circuit on the accuracy of the ground resistance measurement, and can also overcome the asynchronous AC signal interference on the bus. After the data received by the host is processed, on the one hand, it is sent to the LCD display and output alarm, and on the other hand, the data is transmitted to the host computer through the communication interface circuit. the

The parts not described in this embodiment are the same as the prior art.

Claims (4)

1. A mobile insulation monitoring instrument for a substation direct current system, characterized in that: it includes a monitoring host, a data acquisition device and a mobile sensor, and the monitoring host includes a bridge circuit, a protection circuit, an ultra-low frequency signal generator, An analog-to-digital conversion circuit, a microprocessor, an alarm device, a display device, a communication module, and a photoelectric isolation device. The protection circuit realizes busbar monitoring. After the bridge circuit detects that the busbar is grounded, the protection circuit controls the ultra-low frequency signal generator to work and Synchronously output synchronous signals to the data acquisition device, the bridge circuit includes a balanced bridge detection circuit and an unbalanced bridge detection circuit; the protection circuit is connected to the microprocessor by triggering the control ultra-low frequency signal generator, and the bridge circuit passes The conversion is connected with the microprocessor, and the microprocessor is also connected with the communication module, the photoelectric isolation device, the alarm device and the display device, and the photoelectric isolation is connected with the data acquisition device through the serial port; The data acquisition device includes more than one group of connected analog selector switches, amplifiers, bandpass filters, phase comparators, filters, analog-to-digital conversion circuits and microprocessors, and the analog selector switches are passed through mobile The sensor obtains the induced current signal, and the monitoring host controls the operation of the ultra-low frequency signal generator and simultaneously outputs a synchronous signal to the phase comparator of the data acquisition device. After the monitoring host monitors that the bus bar is grounded, the host injects the ultra-low frequency signal source into the DC system, Data acquisition sends the induced current sent by the mobile sensor to the microprocessor for processing through the analog selection switch, amplifier, band-pass filter, phase comparator, filter, and analog-to-digital conversion circuit, and then through the serial circuit of the microprocessor. The interface is sent to the monitoring host; The mobile sensor is stuck on each branch circuit of the bus. 2. A mobile insulation monitoring instrument for substation direct current system according to claim 1, characterized in that: said mobile sensor is a caliper type mobile sensor, said caliper is made of strong magnetic material, and adopts electromagnetic shield. 3. A mobile insulation monitor for a DC system of a substation according to claim 2, wherein the caliper is a caliper-type detection probe equipped with different sizes and shapes. 4. A substation DC system mobile insulation monitor according to claim 3, characterized in that: the amplifier in the data acquisition device is an operation with low noise, low drift, low power consumption, and high isolation amplifier and data amplifier.

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