CN211669333U - AC fleeing positioning detection device for power plant DC system - Google Patents
AC fleeing positioning detection device for power plant DC system Download PDFInfo
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- CN211669333U CN211669333U CN201922230468.0U CN201922230468U CN211669333U CN 211669333 U CN211669333 U CN 211669333U CN 201922230468 U CN201922230468 U CN 201922230468U CN 211669333 U CN211669333 U CN 211669333U
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Abstract
The utility model discloses a direct current system of power plant exchanges and scurries into location detection device, including resonance filter module and harmonious pincerlike ampere meter, resonance filter module includes power frequency filter branch road, frequency conversion filter branch road, inductance-capacitance discrimination electric capacity, switch and NTC thermistor, and harmonious pincerlike ampere meter includes pincerlike ampere meter and establishes the tuned circuit on the pincerlike mutual-inductor, and the tuned circuit includes around the third winding on the pincerlike mutual-inductor and the LC resonant circuit who establishes ties with the third winding, and harmonious pincerlike ampere meter detects each possible branch road on the direct current system in proper order, has or not the alternating current component through the differentiation, finds the trouble branch road. The utility model can search the direct current branch into which the alternating current enters in a short time, can accurately judge whether the incoming alternating current is directly accessed by a resistance or accessed by electromagnetic coupling or accessed by capacitive coupling, and can also have the capability of fast searching for the alternating current entering problem of a direct current system caused by a frequency converter; in addition, the hidden danger of alternating current entering direct current can be eliminated.
Description
Technical Field
The utility model relates to an electric power instrument, in particular to direct current system of power plant exchanges and scurries into location detection device.
Background
The alternating current fleeing into the direct current system is common electromagnetic interference of a secondary system of a power plant, and has more reasons, more common causes are wrong wiring of secondary workers, damage of board cards isolated by alternating current and direct current, poor insulation of plug-in components of a protection device, unreasonable cable shielding grounding, water seepage of outdoor equipment and the like, so that an alternating current power supply flees into the direct current system in a direct or electromagnetic coupling or electric field coupling mode. The 110/220V direct current of the power station is an ungrounded system, once an alternating current component grounded for some reason enters the direct current system, a large alternating current voltage to the ground is superposed on a direct current bus, for a 110V direct current system, the normal voltage to the ground is 50-60V, once the alternating current component enters, the voltage to the ground can be increased to about 220V of alternating current, the alternating current component entering the direct current system can be applied to some intermediate relays through cable distribution capacitors and bus ground capacitors of all direct current loops to cause serious accidents of switch misoperation, and in addition, the alternating current component can have the same frequency with the current voltage of a mutual inductor and can also generate interference on some protection devices and automatic devices to cause device damage and switch misoperation. In addition, due to interference of alternating current entering, the direct current grounding detector often cannot give an alarm correctly, and inconvenience is brought to fault detection.
The secondary direct current system plays a very important role in auxiliary equipment of a power station. In recent years, a plurality of serious accidents are caused by the alternating current channeling of a direct current system of a power station, the alternating current channeling into the direct current system can cause the alternating-current fluctuation of the voltage to ground of the whole system, the peak value of the alternating current channeling into the direct current system can reach several times of the normal voltage to ground of the direct current system, the alternating current channeling into the direct current system is long in duration, the overvoltage not only can easily break down the primary and secondary levels of a secondary direct current power supply board card, but also can cause great accident potential to a secondary system of the power station through the forms of cable. In recent years, false tripping accidents caused by alternating current channeling of a direct current system occur successively, however, an alternating current channeling detection device in the prior art can only detect alternating current components of voltage to ground of a direct current bus, does not have a source positioning detection function of alternating current channeling, does not have the attribute of an alternating current source, and is resistive direct access, electromagnetic coupling channeling or capacitive coupling channeling; in addition, with the popularization of high-low voltage frequency converters in power plants, alternating current channeling is probably caused by low-frequency alternating current of the frequency converters, and due to low frequency, the existing direct current grounding detection device injected by low-frequency signals cannot be used at all.
SUMMERY OF THE UTILITY MODEL
The utility model discloses the purpose is: for overcoming the defect that prior art exists, the utility model provides a direct current system of power plant exchanges and scurries into location detection device.
The technical scheme of the utility model is that:
a power plant direct current system alternating current flees into location detection device, it includes a resonance filter module and a tuning pincerlike ampere meter, the said resonance filter module includes power frequency filter branch, frequency conversion filter branch, inductance and capacitance discrimination electric capacity, switch and NTC thermistor, the said power frequency filter branch and frequency conversion filter branch are connected in parallel, one end of parallel connection links with a signal input end of the said resonance filter module through the said NTC thermistor, another end of parallel connection links with another signal input end of the resonance filter module through the capacitance discrimination electric capacity, the said switch and inductance and capacitance discrimination electric capacity are connected in parallel; two signal input ends of the resonance filtering module are respectively connected with a positive or negative bus and the ground of the direct current system; the tuning clamp-on ammeter sequentially detects each possible branch on the direct current system, and finds out a fault branch by judging whether an alternating current component exists or not.
Preferably, the power frequency filtering branch comprises a power frequency resonance capacitor, a power frequency resonance inductor and a power frequency ammeter, and two ends of the power frequency resonance capacitor are respectively connected in series with the power frequency resonance inductor and the power frequency ammeter; the frequency conversion filtering branch circuit comprises a frequency conversion resonant capacitor, a frequency conversion resonant inductor, an auto-coupling voltage regulator and a frequency conversion ammeter, wherein two ends of the frequency conversion resonant capacitor are respectively connected with the frequency conversion ammeter and the primary side of the auto-coupling voltage regulator in series, and the frequency conversion resonant inductor is connected with the secondary side of the auto-coupling voltage regulator in parallel.
Preferably, the tuning clamp-on ammeter comprises a clamp-on ammeter and a tuning circuit arranged on a clamp-on transformer of the clamp-on ammeter, and the tuning circuit comprises a third winding wound on the clamp-on transformer, and a resonant capacitor and a variable inductor which are connected in series with the third winding.
Preferably, the power frequency resonance capacitor and the variable frequency resonance capacitor are thin film capacitors, and the capacity is between 2 and 20 microfarads.
Preferably, the power frequency filtering branch is used for filtering a 50Hz power frequency alternating current signal; the variable-frequency filtering branch circuit realizes continuous variable of resonant frequency by changing the winding transformation ratio of the inductance element at the secondary side of the autotransformer, and is used for filtering alternating current signals with variable frequency and detecting output signals of the frequency converter.
Preferably, the capacitance sensing discrimination capacitor realizes detection of alternating current intrusion property, when the resonance filtering branch is tuned to resonance, the switch is switched off, the capacitance sensing discrimination capacitor is connected in series, and at the moment, whether the incoming alternating current enters through the capacitor or the inductor can be discriminated by observing the change of the resonance current of the ammeter.
The utility model has the advantages that:
1. the utility model overcomes the problem that the prior art can not detect the AC fleeing source of the DC system, can utilize the attached pincerlike ammeter to perform nondestructive detection, find the DC branch circuit where the AC flees in a short time, and further quickly find the fault position;
2. the utility model discloses can effectively detect the attribute that exchanges and scurry into, can accurately judge that the alternating current that spreads into is resistive direct access, or electromagnetic coupling scurry into, or capacitive coupling scurry into to provide more powerful information for the search for the fault point, can accelerate the search for the fault point, can figure out the trouble cause again, be insulating badly or electromagnetism or electric field coupling lead to;
3. the utility model discloses can effectively detect the problem that converter alternating current output signal scurried into direct current system, along with the popularization of high-low voltage converter in the power plant, it is probably that the low frequency alternating current of converter leads to scurrie into to exchange, because the frequency is low, current direct current ground detection device who relies on low frequency signal injection has nothing to do, the low frequency alternating signal who adds converter output is PWM modulation wave, its abundant harmonic can act as the carrier wave, scurries into direct current system through multiple coupling form, and the utility model discloses with the help of continuous adjustable resonance filtering return circuit, to the direct current system alternating current that the converter causes scurries into the problem, also can possess the quick searching ability;
4. the utility model discloses resonance filter module can form the impedance in base to scurrying into DC system's alternating current component to make the alternating current composition of invasion by the filtering, make the alternating current component of invasion can not continue to conduct other return circuits through the direct current generating line again, thereby scurrying into the overvoltage and the possible hidden danger that the direct current leads to with exchanging and reducing to minimumly, play the effect that eliminates to exchange and scurrying into the direct current hidden danger. It can be seen that the utility model discloses can fundamentally solve the not enough that prior art exists, powerful overcome direct current system and exchange a series of great hidden dangers of scurrying into and leading to.
Drawings
The invention will be further described with reference to the following drawings and examples:
fig. 1 is a circuit diagram of the resonant filtering module of the present invention;
FIG. 2 is a circuit diagram of the tuning clamp-on ammeter of the present invention;
FIG. 3 is a schematic diagram of the present invention looking for AC to DC crosstalk;
FIG. 4 is an equivalent circuit of AC ingress of the DC system of the power plant;
fig. 5 is an equivalent circuit of a resonance filtering branch circuit arranged after alternating current of a direct current system of a power plant enters.
Detailed Description
The utility model discloses a positioning and detecting device for AC fleeing of a power plant DC system, which comprises a resonance filtering module 1 and a tuning pincerlike ammeter 12, wherein two signal input ends of the resonance filtering module 1 are respectively connected with a positive or negative bus of the DC system and the ground; the tuning clamp-on ammeter 12 sequentially detects each possible branch on the dc system, and finds a fault branch by determining whether there is an ac current component. Fig. 3 is a schematic diagram of the present invention looking for alternating current to flee into direct current.
As shown in fig. 1, the resonance filtering module 1 includes a power frequency resonance capacitor 2, a power frequency resonance inductor 3, a variable frequency resonance capacitor 4, a variable frequency resonance inductor 5, an auto-coupling voltage regulator 6, a power frequency ammeter 7, a variable frequency ammeter 8, an inductance-capacitance judging capacitor 9, and a switch 10, wherein after the power frequency resonance capacitor 2 is connected in series with the power frequency resonance inductor 3 and the power frequency ammeter 7, one end of the capacitor is connected to one signal input end of the resonance filtering module 1, and the other end of the capacitor is connected to one end of the inductance-capacitance judging capacitor 9; the primary side of a variable-frequency resonant capacitor 4 is connected in series with the primary side of an automatic coupling voltage regulator 6, and then is connected in series with a variable-frequency ammeter 8, one end of the variable-frequency resonant capacitor is connected with one signal input end of a resonant filter module 1, the other end of the variable-frequency resonant capacitor is connected with one end of an inductance-capacitance judging capacitor 9, the other end of the inductance-capacitance judging capacitor 9 is connected with the other signal input end of the resonant filter module 1, and a variable-frequency resonant inductor 5; the switch 10 is connected in parallel with the capacitance-sensing discrimination capacitor 9.
Referring to the attached drawing 2, the utility model discloses a clamp meter for detection is harmonious type clamp meter, through additional harmonious return circuit, can make the clamp meter sensitive to the signal of a certain specific frequency, just so can conveniently to have frequency conversion or power frequency interference's direct current system simultaneously, carries out the invasion source detection of interchange, only needs to carry out the jaw with this clamp meter to each branch road load current of direct current branch screen and measures, surveys the fault branch road that is promptly that has alternating current to the realization is the location detection of scurrying into.
An equivalent circuit of alternating current fleeing into a direct current system of a power plant is shown in fig. 4, wherein U1 is direct current power supply voltage of the direct current system, points A and B represent positive and negative buses, R1 and C1 are direct current system ground distributed capacitors and ground resistors, U2 is a fleeing alternating current power supply, and the alternating current power supply is added between the ground and positive or negative of the direct current system through an impedance R2 or a capacitive reactance C2 (a cable induction mode) to form alternating current intrusion. Setting U2= sinwt, and according to the circuit principle, the voltages to ground of the positive and negative buses of the direct current system are respectively:
therefore, after alternating current flees into the system, the magnitude of overvoltage to ground of the direct current system is related to impedance parameters of the system, and the larger the insulation resistance to ground of the system is, the smaller the distributed capacitance is, and the larger the amplitude of the overvoltage is; meanwhile, the smaller the transition impedance of the ac intrusion point is, the larger the overvoltage amplitude is, and to reduce the overvoltage amplitude, it is necessary to reduce the ground insulation of the dc system and increase the ground distributed capacitance, but these parameters of the dc system cannot be increased at will, if a resonant filtering branch is provided on the dc bus, as shown in fig. 5, the filtering branch is tuned to the power frequency resonance, that is, wL =1/wC3, ignoring the resistance of the filtering branch, and substituting (1), (2) to obtain:
therefore, the leaked alternating current is completely absorbed by the resonant circuit, the voltage to ground of the direct current system is only related to the system resistance component, when the alternating current system has no transition impedance and the metal material invades the direct current system, the direct current system only shows the voltage to ground distribution when the direct current is grounded, and the leaked alternating current overvoltage component is eliminated.
The utility model discloses a set up resonance filter 1, connect between positive and negative generating line of direct current system and the ground through its signal input part, resonance filter effect through the LC filtering branch road, on the one hand, afferent alternating current component has been eliminated, on the other hand, also make the alternating current invasion component increase that flows in the direct current generating line, the alternating current invasion component that makes normal direct current branch road simultaneously reduces to being close to zero, thus, through a pincerlike ampere meter, detect each possible branch road on the direct current system in proper order, through judging whether there is the alternating current component, just can be more quick find trouble branch road. The utility model discloses be equipped with two sets of different resonance filtering branch roads, a set of power frequency filtering branch road that is for filtering 50 Hz's power frequency alternating current signal, another a set of frequency conversion filtering branch road, change secondary side inductance element's winding transformation ratio through the voltage regulator, realize that resonant frequency is continuous variable, be used for the changeable alternating current signal of filtering frequency, just so can carry out effective detection to the output signal of converter. The utility model discloses an electric capacity is differentiateed to the inductance-capacitance, realizes exchanging the detection of invasion attribute, and when resonance filtering branch road tune to the resonance, disconnection switch 10, electric capacity cluster were gone into, and the resonance current through observing the ampere meter changes this moment, just can distinguish that afferent interchange is scurried into through electric capacity or inductance to help find out scurries into the attribute of alternating current component. The power frequency resonance capacitor 2 and the variable frequency resonance capacitor 4 are film capacitors, the capacity of the film capacitors is between 2 and 20 microfarads, the frequency stability of the resonance circuit can be further improved, and meanwhile, overlarge capacitance to the ground cannot be added to a direct current system of a power plant. The NTC thermistor is used for detecting the moment when the circuit is connected into a direct current system, and slowing down the charging impact current of the capacitor.
The utility model overcomes prior art can't detect direct current system exchanges and scurries into the source problem, and usable subsidiary tong-type ampere meter nondestructive test finds the direct current branch road that exchanges and scurries into in the short time, and then seeks out the fault location fast.
The utility model discloses can effectively detect the attribute that exchanges and scurry into, can accurately judge that the interchange that spreads into is resistive direct access, still electromagnetic coupling scurries into, or capacitive coupling scurries into to for the seeking of fault point provides more powerful information, can accelerate the seeking of fault point, can find out the trouble cause again, be insulating bad or electromagnetism or electric field coupling lead to.
The utility model discloses can effectively detect converter alternating current output signal and scurry the problem of going into DC system, along with the popularization of high-low voltage converter in the power plant, it is probably that the low frequency interchange of converter leads to exchange to scurry, because the frequency is low, current direct current ground connection detection device who relies on low frequency signal injection completely can not be for doing all, the low frequency alternating current signal who adds the converter output is PWM modulation wave, its abundant harmonic can act as the carrier wave, scurry into DC system through multiple coupling form, and the utility model discloses with the help of continuous adjustable's resonance filtering return circuit, scurry into the problem to the DC system interchange that the converter causes, also can possess the ability of looking for fast.
The utility model discloses resonance filter module can form the impedance in base to scurrying into DC system's alternating current component to make the alternating current composition of invasion by the filtering, make the alternating current component of invasion can not continue to conduct other return circuits through the direct current generating line again, thereby scurrying into the overvoltage and the possible hidden danger that the direct current leads to with exchanging and reducing to minimumly, play the effect that eliminates to exchange and scurrying into the direct current hidden danger. It can be seen that the utility model discloses can fundamentally solve the not enough that prior art exists, powerful overcome direct current system and exchange a series of great hidden dangers of scurrying into and leading to.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, which cannot limit the protection scope of the present invention. All modifications made according to the spirit of the main technical scheme of the present invention shall be covered within the protection scope of the present invention.
Claims (4)
1. The alternating current channeling positioning detection device for the direct current system of the power plant is characterized by comprising a resonance filtering module (1) and a tuning pincerlike ammeter (12), wherein the resonance filtering module (1) comprises a power frequency filtering branch circuit, a frequency conversion filtering branch circuit, an inductance-capacitance judging capacitor (9), a switch (10) and an NTC thermistor (17), the power frequency filtering branch circuit and the frequency conversion filtering branch circuit are mutually connected in parallel, one parallel end of the power frequency filtering branch circuit is connected with one signal input end of the resonance filtering module (1) through the NTC thermistor (17), the other parallel end of the power frequency filtering branch circuit is connected with the other signal input end of the resonance filtering module (1) through the inductance-capacitance judging capacitor (9), and the switch (10) is connected with the inductance-capacitance judging capacitor (9) in parallel; two signal input ends of the resonance filtering module (1) are respectively connected with a positive or negative pole bus and the ground of a direct current system; the tuning clamp-on ammeter (12) sequentially detects each possible branch on the direct current system, and finds out a fault branch by judging whether an alternating current component exists or not.
2. The power plant direct current system alternating current fleeing positioning detection device according to claim 1, characterized in that the power frequency filtering branch comprises a power frequency resonance capacitor (2), a power frequency resonance inductor (3) and a power frequency ammeter (7), wherein two ends of the power frequency resonance capacitor (2) are respectively connected in series with the power frequency resonance inductor (3) and the power frequency ammeter (7); the frequency conversion filtering branch circuit comprises a frequency conversion resonant capacitor (4), a frequency conversion resonant inductor (5), an auto-coupling voltage regulator (6) and a frequency conversion ammeter (8), wherein two ends of the frequency conversion resonant capacitor (4) are connected with the primary side of the frequency conversion ammeter (8) and the auto-coupling voltage regulator (6) in series, and the frequency conversion resonant inductor (5) is connected with the secondary side of the auto-coupling voltage regulator (6) in parallel.
3. The ac channeling location detection device of the dc system of the power plant according to claim 2, wherein the tuning clamp ammeter (12) is composed of a clamp ammeter (16) and a tuning circuit provided on a clamp transformer of the clamp ammeter, and the tuning circuit is composed of a third winding (13) wound on the clamp transformer and a resonant capacitor (14) and a variable inductor (15) connected in series with the third winding (13).
4. The power plant direct current system alternating current channeling positioning detection device according to claim 2, wherein the power frequency resonance capacitor (2) and the variable frequency resonance capacitor (4) are film capacitors with a capacity of 2-20 microfarads.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922230468.0U CN211669333U (en) | 2019-12-13 | 2019-12-13 | AC fleeing positioning detection device for power plant DC system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922230468.0U CN211669333U (en) | 2019-12-13 | 2019-12-13 | AC fleeing positioning detection device for power plant DC system |
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| Publication Number | Publication Date |
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| CN211669333U true CN211669333U (en) | 2020-10-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201922230468.0U Active CN211669333U (en) | 2019-12-13 | 2019-12-13 | AC fleeing positioning detection device for power plant DC system |
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| CN (1) | CN211669333U (en) |
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