CN103675613B - Transformer station DC system movable type insulation supervision instrument - Google Patents

Abstract

The invention discloses a mobile insulation monitoring instrument for substation DC system, 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 modulus 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 present invention has the characteristics of being mobile, and can detect multiple circuits at the same time, and the automation program is highly adaptable, and can perform supervision and inspection on the original DC system bridge of the substation, but Detect the impedance of the original bridge, and set the original circuit through the setting menu.

Description

Substation DC system mobile insulation monitor

technical field

The invention relates to an insulation monitor, in particular to a mobile insulation monitor 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.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a mobile insulation monitoring system for substation DC systems that is suitable for various DC systems and can be put into use in an emergency, thereby ensuring the normal operation of the DC system in a timely and effective manner. instrument.

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 through a trigger control ultra-low frequency signal generator, and the bridge circuit is connected to the microprocessor through an analog-to-digital conversion circuit 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, band-pass filters, phase comparators, filters, analog-to-digital conversion circuits and microprocessors, and the analog selector switches are connected 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 DC system of the substation of the present invention can realize the grounding of the DC system line, the branch grounding search, the overvoltage and undervoltage detection, and provide alarm information output and display device display according to the detection results, and at the same time, the data can also be passed through The communication interface circuit is sent to the host computer. Since the present invention 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 ground fault on the branch circuit. The impact of capacitance 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: set according to the principle of the original DC system power monitor on site, when the circuit of the original substation is a balanced bridge circuit, If the bridge cannot exit after the equipment fails, when it is put into the mobile insulation monitor of the DC system of the substation, first use the unbalanced bridge circuit to monitor, set the correction value of the device parameters to 0 and then put it into measurement, and measure the original equipment On the resistance value of the balance bridge circuit, the measured resistance value is corrected as a correction value, and then the balance bridge circuit is selected for measurement. When the monitor calculates the grounding resistance, the CPU will change it according to the set correction value. The coefficient in the original calculation formula can eliminate the influence of the original balanced bridge circuit, so that the re-invested equipment can be monitored accurately without false alarms; when the original substation circuit is an unbalanced bridge circuit, if the original DC system power supply monitoring After the equipment fails, in order to prevent the two sets of unbalanced bridge circuit working devices from being put into use at the same time, causing false detection or false alarm, it is necessary to turn off the power of the faulty device first, and use the above unbalanced bridge circuit method to measure in the same way. Data correction, and then put into the operation of the unbalanced bridge circuit, due to the unbalanced bridge 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, and the data obtained from the experiment The list is stored in the register, and then the table look-up calculation is performed according to the original set correction value to eliminate the influence of the original balance bridge circuit on the measurement accuracy, 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.

The workflow of the microprocessor of the described supervisory host is:

After setting the correct parameters of the mobile insulation monitoring device, the monitoring device will be put into operation normally, and the bus voltage and the insulation of the bus to ground will be detected in real time.

When the operating voltage collected by the DC bus is compared with the set value of overvoltage or undervoltage set by the device, when the set value exceeds the set value, an alarm of "bus overvoltage" or "bus undervoltage" will be issued, and the "overvoltage" on the panel of the drive host device will be lit. Pressure alarm" or "undervoltage alarm" indicator light, and at the same time turn on the "overvoltage alarm" hard contact,

Then, according to the set electric bridge, detect the insulation condition of the busbar to the ground. When the detected resistance value of the busbar to the ground is lower than the set insulation resistance value, an "insulation alarm" will be issued, and the "insulation alarm" indicator light on the panel of the drive host device will be turned on. Simultaneously connect the "insulation alarm" hard contact,

After detecting the grounding of the bus bar, the host CPU controls the ultra-low frequency signal generator to inject the ultra-low frequency AC signal into the bus bar, and at the same time sends a synchronous signal to the phase comparator of the data acquisition device.

The data acquisition device 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 line interface is sent to the monitoring host, and the monitoring host inspects the sampling information of the branches one by one. The information includes the amplitude and phase, and compares it with the grounding threshold value of the branch set by the device, so as to determine the grounding branch and the grounding resistance. value, after detecting that a branch circuit is grounded, a "branch circuit alarm" will be issued, the "branch circuit alarm" indicator light on the panel of the drive host device will be lit, and the "branch circuit alarm" hard contact will be connected at the same time. All inspections are performed once, and no grounding branch is found, then return to the starting point for busbar detection, repeat the above work,

After the above-mentioned equipment alarms, the CPU controls the communication module at the same time, and uploads the alarm and action information to the remote monitoring system through 485, 232 and other communication methods.

In summary, compared with the prior art, the present invention has the following advantages:

The mobile insulation monitoring instrument of the DC system of the substation of the present invention has the characteristics of being mobile, 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, but Detect the impedance of the original bridge, set the original circuit through the setting menu, detect the balance bridge of the original system during normal operation, use the equipment to restore the normal operation interface, and use this equipment as a substation for multiple substations spare equipment. The application of the mobile insulation monitor for the substation DC system of the present invention 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 of equipment Cost; Due to the high degree of automation and easy movement of the equipment, the efficiency of substations to eliminate insulation faults in the DC system is greatly improved, and the power loss caused by the removal of insulation faults 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.

Description of drawings

Fig. 1 is the circuit composition of the mobile insulation monitoring instrument of the DC system of the substation of the present invention.

Figure 2 is a flow chart of monitoring the host microprocessor.

detailed description

The present invention will be described in more detail below in conjunction with examples.

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

Claims (5)

1. a kind of transformer station DC system movable type insulation supervision instrument, it is characterised in that：Include supervision main frame, data acquisition dress Put and mobile sensor, described supervision main frame includes bridge circuit, protection circuit, Signal Generator of Ultra-low Frequency, modulus Change-over circuit, microprocessor, warning device, display device, communication module, optical isolation, the protection circuit are realized female Line is monitored, after bridge circuit detects busbar grounding, protection circuit control Signal Generator of Ultra-low Frequency work and synchronism output Synchronizing signal is to data acquisition device, and described bridge circuit includes balance bridge detection circuit and uneven bridge detects circuit; Protection circuit is connected by triggering control Signal Generator of Ultra-low Frequency with microprocessor, bridge circuit by analog to digital conversion circuit and Microprocessor be connected, microprocessor is also connected with communication module, optical isolation, warning device and display device, photoelectricity every Data acquisition device is connected by serial ports from device；

Described data acquisition device include more than one group the analog selection being connected switch, amplifier, bandpass filter, Phase comparator, wave filter, analog to digital conversion circuit and microprocessor, described analog selection switch are obtained by mobile sensor Sensor current signal is taken, described supervision host computer control Signal Generator of Ultra-low Frequency work exports synchronizing signal and adopted to data simultaneously The phase comparator of acquisition means, after supervision host supervision to busbar grounding, main frame injects ultra-low frequency signal source to straight-flow system, Data acquisition device is switched the induced-current sent of mobile sensor is received through analog selection, amplifier, bandpass filter, Phase comparator, wave filter, analog to digital conversion circuit feeding microprocessor are handled, then sent by the serial line interface of microprocessor Enter to supervise main frame；

The mobile sensor is stuck on each branch-path of bus, if there is resistance eutral grounding on branch-path, is mounted in Sensor on the branch road produces induced-current, and faradic size and the resistance of grounding resistance are inversely proportional, described Balance bridge detection circuit detects being set as circuit with uneven bridge in bridge circuit：Supervised according to live original straight-flow system power supply The principle for surveying instrument is set, when the circuit of original transformer station detects circuit for balance bridge, if equipment produces electric bridge after failure It can not exit, when putting into transformer station DC system movable type insulation supervision instrument again, first using uneven bridge detection circuit monitoring When, the correction value of setting device parameter puts into measurement again for 0, measures the resistance value on balance bridge detection circuit on original equipment, will The resistance value measured is done after correction value is modified, and reselection balance bridge detection circuit measuring, monitor is asking for earth resistance When, CPU can change the coefficient in former computing formula according to the correction value of setting, you can eliminate former balance bridge detection circuit shadow Ring, make the monitoring of equipment put into again accurate, wrong report will not be produced；When the circuit of original transformer station is uneven bridge detection circuit When, if former straight-flow system power supply monitoring equipment is produced after failure, to prevent the device of two sets of uneven bridge detection circuit work same When put into, caused error detection or wrong report, needing first will be after failed equipment power-off, similarly using above-mentioned uneven bridge detection electricity Path method is measured, and carries out data correction, and uneven bridge detection circuit operation is then put into again,

Because uneven bridge detects circuit monitoring, computing formula is more complicated, when to relatively large grounded resistance, computational accuracy compared with Difference, therefore test inhabitant area method is taken, the data list obtained by experiment is stored in register, then looked into by original setting correction value Meter calculation is handled, and eliminate former balance bridge detection circuit influences on the precision of measurement, makes the monitoring of equipment put into again accurate, will not produce Raw wrong report.

2. a kind of transformer station DC system movable type insulation supervision instrument according to claim 1, it is characterised in that：Described Mobile sensor is caliper brake movable sensor, and described clamp are made up of ferromagnetic material, and using electromagnetic shielding.

3. a kind of transformer station DC system movable type insulation supervision instrument according to claim 2, it is characterised in that：Described Clamp are the caliper brake detection probe for being configured with different size and shapes.

4. a kind of transformer station DC system movable type insulation supervision instrument according to claim 3, it is characterised in that：Described Amplifier in data acquisition device is to be put using low noise, low drifting, low-power consumption, the operational amplifier of high-isolation and data Big device.

5. a kind of transformer station DC system movable type insulation supervision instrument according to claim 4, it is characterised in that：Described The workflow of microprocessor for supervising main frame is：

After correct parameter setting is carried out to mobile insulation monitor, supervisory device normal operation carries out bus in real time Voltage and bus insulation against ground detection,

When the working voltage and device that dc bus is gathered set superpressure or under-voltage definite value to be compared, after setting definite value When, then " bus superpressure " or " bus is under-voltage " alarm is sent, driving host apparatus panel " overpressure alarm " or " under-voltage report is lighted It is alert " indicator lamp, " ultra under-pressure alarm " hard contact is also turned on,

Then according to the electric bridge of setting, bus insulation against ground situation is detected, is insulated when detection bus resistance to earth value is less than to set During resistance definite value, then " insulation alarm " is sent, light driving host apparatus panel " insulation alarm " indicator lamp, be also turned on " absolutely Edge is alarmed " hard contact,

After detection busbar grounding, host CPU controls Signal Generator of Ultra-low Frequency to inject ultralow frequency AC signal to bus, simultaneously Synchronizing signal is sent to the phase-contrast device of data acquisition device,

Data acquisition device switchs the induced-current that reception mobile sensor is sent through analog selection, amplifier, band logical filter Ripple device, phase comparator, wave filter, analog to digital conversion circuit feeding microprocessor are handled, then pass through the serial of microprocessor Interface feeding supervision main frame, supervision main frame includes amplitude and phase, set with device by road inspection branch road sample information, described information Fixed grounding threshold value is compared, so as to judge ground connection branch road and grounding resistance, is connect having detected branch road " branch road alarm " behind ground, is sent, driving host apparatus panel " branch road alarm " indicator lamp is lighted, is also turned on " branch road alarm " hard Contact, if to the whole inspections of all branch roads one time, not finding to be grounded branch road, then returning to starting point and carry out bus inspection Survey, repeat above-mentioned work,

After the said equipment alarm, CPU will be while communication control module, will be alarmed and action message by 485,232 communication modes Upload remote monitoring system.