CN114301046A - Distribution network ground fault arc extinction method and device based on electrodeless voltage regulation - Google Patents
Distribution network ground fault arc extinction method and device based on electrodeless voltage regulation Download PDFInfo
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- CN114301046A CN114301046A CN202111463374.3A CN202111463374A CN114301046A CN 114301046 A CN114301046 A CN 114301046A CN 202111463374 A CN202111463374 A CN 202111463374A CN 114301046 A CN114301046 A CN 114301046A
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Abstract
The invention discloses a distribution network ground fault arc extinction method and device based on electrodeless voltage regulation, relates to the technical field of power systems, and aims to obtain a voltage suppression neutral point voltage opposite to a fault phase by using a low-voltage side voltage of a zigzag transformer, quickly switch a neutral point series resistor, change the neutral point voltage and quickly judge whether the fault point disappears. Compared with an active arc extinction device utilizing power electronic devices, the device realizes arc extinction through a simple transformer and resistor selection and a stepless on-load voltage regulator, and has the advantages of simple structure, low cost and strong adaptability and stability.
Description
Technical Field
The invention belongs to the technical field of power systems, and particularly relates to a distribution network ground fault arc extinction method and device based on electrodeless voltage regulation.
Background
The distribution network accounts for more than 95% of the power grid, and meanwhile, the distribution network is complex in structure and frequent in single-phase earth faults. Single-phase earth faults easily cause arc light overvoltage, and if the arc light overvoltage cannot be timely processed, accidents such as electric shock, fire, power failure and the like can be caused. At present, two grounding fault handling methods exist, one of the two methods is a large-current grounding method, the neutral point of the method adopts small resistance grounding, the fault characteristic quantity is large, and the fault can be tripped in time to cut off a fault line, however, the method causes high fault tripping rate and cannot meet the requirement of a user on the power supply reliability of a power grid. The other fault processing method is a large-current grounding mode, the neutral point is usually adopted to suppress arc overvoltage through an arc suppression coil grounding mode, however, as the occupation ratio of a cable circuit is continuously increased, the capacitance current is continuously increased, the traditional arc suppression coil can only compensate the idle work and has no effect on the active current, the active residual current can reach 50A, and the equipment safety and the personal safety are still seriously threatened. The method is characterized in that a controllable power supply is connected in parallel on a traditional automatic tuning arc-extinguishing coil, zero-sequence voltage with controllable size and waveform is injected into a power distribution network, and the fault phase voltage is controlled to be below the arcing voltage.
In summary, there is a need for an arc extinguishing method and apparatus that has a simple structure and low cost and can reliably extinguish arcs.
Disclosure of Invention
The invention aims to provide a distribution network ground fault arc extinction method and device based on electrodeless voltage regulation, and therefore the defects that an existing arc extinction coil cannot effectively inhibit arc overvoltage and a flexible device is complex in structure are overcome.
In order to achieve the purpose, the invention provides a distribution network ground fault arc extinction device based on electrodeless voltage regulation, which comprises:
the low-voltage side phase selection switching switch cabinet is connected with the low-voltage side of the zigzag transformer, and the high-voltage side of the zigzag transformer is connected with three phases of the power distribution network;
the input end of the electrodeless voltage regulator is connected with the switch wiring end of the low-voltage side phase-selection switching cabinet;
the input end of the injection transformer is connected with the output end of the electrodeless voltage regulator, and the output end of the injection transformer is grounded;
the grounding admittance is connected in parallel with the output end of the injection transformer;
one end of the fault type judging and switching resistor is connected with the output end of the injection transformer;
one end of the breaker is connected with the other end of the fault type judging switching resistor, and the other end of the breaker is connected with a neutral point led out from the high-voltage side of the zigzag transformer; and
and the central processing unit is respectively connected with the low-voltage side phase-selection switching switch cabinet, the electrodeless voltage regulator, the fault type judging switching resistor and the circuit breaker.
Preferably, the ratio of the zigzag transformer is kT1Then the transformation ratio of the injection transformer is 1/kT1。
Preferably, when the zigzag transformer grounding method is ZNY11, the primary side K of the electrodeless voltage regulator is connected to the ground1Secondary side fault phase terminal of terminal connection zigzag transformer, secondary test K of non-polar voltage regulator2The terminal is connected with a corresponding terminal of the zigzag transformer secondary side with fault phase advanced by 120 degrees, and after voltage opposite to the fault phase is boosted, fault point electric arcs are restrained.
If the phase A has a ground fault, the voltage at the two ends of the injection transformer is as follows:
Uinj＝-KUAO
in the above formula, UinjIs the voltage injected into the high side of the transformer. K is the transformation ratio of the stepless voltage regulator, UAOIs the voltage of the distribution network a relative to the neutral point.
As the preferable technical proposal, the utility model also comprises a closed work cabinet and an outdoor protective shell,
the closed working cabinet is used for placing a low-voltage side phase-selection switching switch cabinet, a non-polar voltage regulator, an injection transformer, a fault type judging switching resistor, a circuit breaker and a central processing unit;
the outdoor protective shell is used for placing the closed working cabinet.
As an optimized technical scheme, one closed work cabinet is used for installing a low-voltage side phase-selection switching switch cabinet, a non-polar voltage regulator, an injection transformer, a fault type judging switching resistor, a circuit breaker or a central processing unit.
The distribution network ground fault arc extinction method based on the electrodeless voltage regulation applies the distribution network ground fault arc extinction device based on the electrodeless voltage regulation, and comprises the following steps:
the distribution network ground fault arc extinction device based on the electrodeless voltage regulation obtains voltage suppression neutral point voltage opposite to a fault by using the low-voltage side voltage of the zigzag transformer, and quickly switches the neutral point series resistor to quickly judge whether the fault point disappears.
As an optimal technical scheme, the distribution network ground fault arc extinction device based on the electrodeless voltage regulation obtains a voltage suppression neutral point voltage opposite to a fault by using a low-voltage side voltage of a zigzag transformer, quickly switches a neutral point series resistor, and quickly judges whether the fault point disappears, and specifically comprises the following steps:
the method comprises the steps that a central processing unit monitors neutral point voltage, when zero sequence voltage of a neutral point is larger than a phase voltage threshold value, a fault of a distributed single network is judged, and a fault phase with the lowest phase voltage is judged;
the switch of the low-voltage side phase-selecting switching switch cabinet is controlled to be connected with a terminal fault phase led out by the low-voltage side phase-selecting switching switch cabinet in advance, the transformation ratio of the electrodeless on-load voltage regulator is adjusted to be maximum, the injection transformer is boosted, the vacuum circuit breaker is set to be closed, the switch of the fault type judging switching resistor is connected with a non-resistance end, the voltage of the fault phase is suppressed to 0, and the arc extinction of the fault is realized.
As a preferred technical scheme, whether a fault point disappears is quickly judged, and the method specifically includes:
sliding a carbon brush of the electrodeless voltage regulator, reducing the transformation ratio K <1 of the electrodeless voltage regulator, disconnecting a switch 1 of the fault type judging switching resistor, closing the switch of the fault type judging switching resistor to K2 or K3, and reducing the neutral point voltage; monitoring whether a zero sequence admittance phase angle of the power distribution network changes, if not, judging that the fault disappears, restoring each switch and the carbon brush to the original position, and restoring the normal operation of the power distribution network; and otherwise, recovering the carbon brush until K is equal to 1, judging the fault type to 1 by the switching resistor, continuing to perform arc extinction of the ground fault, and waiting for fault treatment.
As a preferred technical solution, the impedance of the zero-sequence voltage of the neutral point is:
in the formula, g is the earth electric conductivity of the power distribution network, C is the earth capacitance of the power distribution network, M is the voltage division coefficient of the neutral point after the resistor is switched, K is the transformation ratio of the electrodeless voltage regulator, and R isfIs the fault point ground impedance.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a distribution network ground fault arc extinction method and device based on electrodeless voltage regulation, which can realize fault arc extinction by combining a distribution network ground fault arc extinction method based on electrodeless voltage regulation with a distribution network ground fault arc extinction device based on electrodeless voltage regulation, namely, a central processing unit monitors neutral point zero sequence voltage through a circuit breaker, a zero sequence voltage threshold value is set, when the zero sequence voltage exceeds the threshold value, the fault phase is judged as a sending fault, then the central processing unit controls a switch of a low-voltage side phase selection switching cabinet to be connected with a terminal fault phase lead-out by the low-voltage side phase selection switching cabinet in advance, the transformation ratio of an electrodeless on-load voltage regulator is adjusted to be maximum, a vacuum circuit breaker is set to be closed, the switch of a fault type judgment resistor is connected with a non-resistance end, so that the voltage of the fault phase is suppressed to be 0, and the fault arc extinction is realized.
The invention can realize fault arc extinction through a simple connecting structure and a transformer, has simple structure, high reliability, simple control method and low cost; meanwhile, the device adopts a structural module, and is simple to overhaul.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only one embodiment of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a formal section of a distribution network ground fault arc extinction device based on electrodeless voltage regulation according to one embodiment of the invention;
FIG. 2 is a schematic circuit diagram of one embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of one embodiment of the present invention;
wherein: 1. an outdoor protective housing; 2. a shock absorbing material; 3. a filler material; 4. a central processing unit; 5. a human-computer interaction module; 6. a low-voltage side phase selection switching switch cabinet; 7. a stepless on-load voltage regulator; 8. injecting the transformer; 9. judging a switching resistor according to the fault type; 10. a circuit breaker;
FIG. 4 is a graph of the vector relationship of the primary side three-phase voltages of a zigzag transformer in accordance with one embodiment of the present invention;
fig. 5 is a flow chart of the operation of the distribution network ground fault arc extinction device based on the electrodeless voltage regulation according to one embodiment of the invention.
Detailed Description
The technical solutions in the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that, as used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and further it is to be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the features, steps, operations and/or combinations thereof.
Fig. 1 shows an electric distribution network ground fault arc extinction device based on electrodeless voltage regulation in one embodiment provided by the invention, which comprises: a low-voltage side phase-selection switching switch cabinet 6, a non-polar voltage regulator, an injection transformer 8, a fault type judging switching resistor 9, a circuit breaker 10 and a central processing unit 4,
the low-voltage side phase selection switching switch cabinet 6 is connected with the low-voltage side of the zigzag transformer, and the high-voltage side of the zigzag transformer is connected with three phases of a power distribution network;
the input end of the electrodeless voltage regulator is connected with the switch wiring end of the low-voltage side phase-selection switching cabinet 6, and the electrodeless voltage regulator is used for changing the transformation ratio of the electrodeless on-load voltage regulator 77, changing the magnitude of injection voltage, providing data support, judging the fault type and the like;
the input end of the injection transformer 8 is connected with the output end of the electrodeless voltage regulator, the output end of the injection transformer 8 is connected with the grounding admittance in parallel, one end of the grounding admittance is grounded, and the injection transformer 8 is used for increasing the secondary side voltage of the electrodeless on-load voltage regulator 7;
a fault type judging and switching resistor 9, one end of which is connected with the output end (namely the other end of the ground admittance) of the injection transformer 8, and the fault type judging and switching resistor is used for further reducing the neutral point voltage and providing data support to judge the fault type;
one end of the circuit breaker 10 is connected with the other end of the fault type judging switching resistor 9, the other end of the circuit breaker 10 is connected with a neutral point led out from the high-voltage side of the zigzag transformer, when a fault is monitored, the circuit breaker 10 is closed, and the work of a power distribution network ground fault arc extinction device based on electrodeless voltage regulation is controlled;
and the central processing unit 4 is respectively connected with the low-voltage side phase selection switching switch cabinet 6, the electrodeless voltage regulator, the fault type judgment switching resistor 9 and the circuit breaker 10, and the central processing unit 44 monitors the zero-sequence voltage of the neutral point of the power distribution network, the voltage of each phase and the zero-sequence admittance size through setting.
According to the distribution network ground fault arc extinction device based on the electrodeless voltage regulation, the central processing unit 4 monitors the neutral zero-sequence voltage through the circuit breaker 10, when the zero-sequence voltage exceeds the threshold value, the fault is judged to be sent, the fault phase is judged, then the central processing unit 4 controls the switch of the low-voltage side phase selection switching cabinet 6 to be connected with the terminal fault phase led out by the low-voltage side phase selection switching cabinet 6 in advance, the transformation ratio of the electrodeless on-load voltage regulator 7 is adjusted to be the maximum, the voltage of the injection transformer 8 is boosted, the vacuum circuit breaker 10 is set to be closed, the switch of the fault type judgment switching resistor 9 is connected with a non-resistance end, the voltage of the fault phase is suppressed to 0, and fault arc extinction is achieved. Since it is desirable that the neutral point voltage is the phase voltage during arc extinction, the injection transformer 8 boosts the neutral point voltage to the phase voltage, thereby extinguishing the fault.
In one embodiment, the electrodeless voltage regulator adopts an electrodeless on-load voltage regulator 7, and the circuit breaker 10 adopts a vacuum circuit breaker 10.
In one embodiment, the ratio of the meander transformer becomes kT1Then the transformation ratio of the injection transformer 8 is 1/kT1。
In an embodiment, if the grounding mode of the zigzag transformer is ZNY11, the primary side K of the electrodeless voltage regulator is connected to ground1Secondary side fault phase terminal of terminal connection zigzag transformer, secondary test K of non-polar voltage regulator2The terminal is connected with a corresponding terminal of the zigzag transformer secondary side with fault phase advanced by 120 degrees, and after voltage opposite to the fault phase is boosted, fault point electric arcs are restrained.
If phase a has a ground fault, the voltage across injection transformer 8 is:
Uinj＝-KUAO
in the above formula, UinjIs the voltage injected into the high side of the transformer. K is the transformation ratio of the stepless voltage regulator, UAOIs the voltage of the distribution network a relative to the neutral point.
In one embodiment, the power distribution network ground fault arc extinction device based on the electrodeless voltage regulation further comprises a closed work cabinet and an outdoor protective shell 1,
the closed working cabinet is used for placing a low-voltage side phase-selection switching switch cabinet 6, a non-polar voltage regulator, an injection transformer 8, a fault type judging switching resistor 9, a circuit breaker 10 and a central processing unit 4;
the outdoor protective shell 1 is used for placing the closed work cabinet.
In one embodiment, one of the closed work cabinets is used for installing a low-voltage side phase-selection switching switch cabinet 6, a non-polar voltage regulator, an injection transformer 8, a fault type judging switching resistor 9, a circuit breaker 10 or a central processing unit 4.
In one embodiment, a filling material 3 is filled between the closed work cabinets.
Specifically, the filler 3 is ceramic fiber.
In one embodiment, the bottom end of the inside of the closed work cabinet is provided with a damping material 2.
Specifically, the damping material 2 is made of damping rubber.
According to one embodiment, the power distribution network ground fault arc extinction device based on the electrodeless voltage regulation further comprises a human-computer interaction module 5, the human-computer interaction module 5 is connected with the central processing unit 4, and the human-computer interaction module 5 is installed outside the closed working cabinet. The human-computer interaction module 5 can control the low-voltage side phase selection switching switch cabinet 6, the electrodeless on-load voltage regulator 7, the injection transformer 8, the fault type judgment switching resistor 9, the circuit breaker 10 and the central processing unit 4, and the states of the low-voltage side phase selection switching switch cabinet 6, the electrodeless on-load voltage regulator 7, the injection transformer 8, the fault type judgment switching resistor 9, the circuit breaker 10 and the central processing unit 4 can be displayed through the human-computer interaction module 5, so that monitoring of the low-voltage side phase selection switching switch cabinet 6, the electrodeless on-load voltage regulator 7, the injection transformer 8, the fault type judgment switching resistor 9, the circuit breaker 10 and the central processing unit 4 by workers is facilitated.
In one embodiment, fig. 2 shows a schematic structural diagram of a formal section of a distribution network ground fault arc extinction device based on electrodeless voltage regulation in one embodiment, a closed working cabinet where the low-voltage side phase-selection switching switch cabinet 6 is located is placed at the lower left side inside the outdoor protective shell 1, and a closed working cabinet where the central processor 4 is located is placed above the closed working cabinet where the low-voltage side phase-selection switching switch cabinet 6 is located; the closed working cabinet where the injection transformer 8 is located is arranged at the lower right side inside the outdoor protective shell 1, the closed working cabinet where the fault type judging switching resistor 9 is located is arranged above the closed working cabinet where the injection transformer 8 is located, and the closed working cabinet where the vacuum circuit breaker 10 is located is arranged above the closed working cabinet where the fault type judging switching resistor 9 is located; the sealed work cabinet where the electrodeless on-load voltage regulator 7 is located is arranged in the middle of the outdoor protective shell 1, namely, is located in a space formed by the sealed work cabinet where the low-voltage side phase-selection switching cabinet 6 is located and the sealed work where the injection transformer 8 is located. And filling materials 3 are filled between the closed work cabinets.
Correspondingly, the human-computer interaction module 5 is installed on the closed work cabinet where the central processing unit 4 is located.
In one embodiment, the closed work cabinet is slidably mounted in the outdoor protective housing 1.
Specifically, the filling material 3 is a connecting plate, and all the connecting plates are fixedly installed, so that a placement space is provided for a closed work cabinet where the low-voltage side phase-selection switching switch cabinet 6, the electrodeless on-load voltage regulator 7, the injection transformer 8, the fault type judgment switching resistor 9, the circuit breaker 10 and the central processing unit 4 are located.
In order to facilitate the maintenance of the closed work cabinets, the drawer guide rails are arranged on the left side and the right side of each closed work cabinet, and the corresponding drawer slide rail parts are structurally embedded on the connecting plates, so that the closed work cabinets can be pushed and pulled out like drawers, and the maintenance is convenient.
In one embodiment, the front side and the rear side of the sealed working cabinet are provided with push-pull grooves, so that the sealed working cabinet can be directly pushed out of the device during maintenance, and the maintenance is convenient.
Fig. 5 shows an arc extinction method for a power distribution network ground fault based on electrodeless voltage regulation, and the arc extinction method for the power distribution network ground fault based on electrodeless voltage regulation applies the arc extinction device for the power distribution network ground fault based on electrodeless voltage regulation, and includes:
judging a fault phase after a fault occurs, and selecting a corresponding phase selection switch cabinet in a distribution network ground fault arc extinction device based on electrodeless voltage regulation;
the distribution network ground fault arc extinction device based on the electrodeless voltage regulation obtains voltage suppression neutral point voltage opposite to a fault by using the low-voltage side voltage of the zigzag transformer, and quickly switches the neutral point series resistor to quickly judge whether the fault point disappears.
According to one embodiment, the distribution network ground fault arc suppression device based on electrodeless voltage regulation utilizes the low-voltage side voltage of a zigzag transformer to obtain the voltage suppression neutral point voltage opposite to the fault, and rapidly switches the neutral point series resistor to rapidly judge whether the fault point disappears, and the method specifically comprises the following steps:
the central processing unit 4 monitors the neutral point voltage, and when the zero sequence voltage of the neutral point is greater than the phase voltage threshold value, the fault of the distributed single network is judged, and the fault phase with the lowest phase voltage is judged;
the switch of the low-voltage side phase-selecting switching switch cabinet 6 is controlled to be connected with a terminal fault phase led out from the low-voltage side phase-selecting switching switch cabinet 6 in advance, the transformation ratio of the electrodeless on-load voltage regulator 7 is adjusted to be maximum, the injection transformer 8 is boosted, the vacuum circuit breaker 10 is set to be closed, the switch of the fault type judging switching resistor 9 is connected with a non-resistance end, the voltage of the fault phase is suppressed to be 0, and the arc extinction of the fault is realized.
One embodiment of the present invention is a method for quickly determining whether a fault point disappears, including:
sliding a carbon brush of the electrodeless voltage regulator, reducing the transformation ratio K <1 of the electrodeless voltage regulator, disconnecting the switch 1 of the fault type judging switching resistor 9, closing the switch of the fault type judging switching resistor 9 to K2 or K3, and reducing the neutral point voltage; monitoring whether a zero sequence admittance phase angle of the power distribution network changes, if not, judging that the fault disappears, restoring each switch and the carbon brush to the original position, and restoring the normal operation of the power distribution network; otherwise, the carbon brush is recovered until K is equal to 1, the switching resistors 9 to 1 are judged according to the fault types, arc extinction of the ground fault is continued, and fault processing is waited.
In one embodiment, the impedance of the zero-sequence voltage of the neutral point is:
in the formula, g is the earth electric conductivity of the power distribution network, C is the earth capacitance of the power distribution network, M is the voltage division coefficient of the neutral point after the resistor is switched, K is the transformation ratio of the electrodeless voltage regulator, and R isfIs the fault point ground impedance.
The invention will be further illustrated with reference to the following examples. So that the person skilled in the art will be better aware of the inventive device:
fig. 3 shows a circuit structure connection of one of the distribution network ground fault arc extinction devices based on the stepless voltage regulation, an input end of a low-voltage side phase selection switching cabinet 6 is connected with a low-voltage side of a voltage transformer of a Z-type grounding transformer, a high-voltage side of the voltage transformer of the Z-type grounding transformer is connected with a three-phase line of the distribution network, an output end of the low-voltage side phase selection switching cabinet 6 is connected with an input end of a stepless on-load voltage regulator 7, an output end of the stepless on-load voltage regulator 7 is connected with an input end of an injection transformer 8, an output end of the injection transformer 8 is connected with a grounding admittance in parallel, one end of the grounding admittance is grounded, the other end of the grounding admittance, a fault type judgment switching resistor 9 and one end of a vacuum circuit breaker 10 are sequentially connected in series, and the other end of the vacuum circuit breaker 10 is connected with a neutral point led out from the high-voltage side of the voltage transformer of the type grounding transformer.
The low-voltage side phase-selection switching switch cabinet 6 is of an MDS2A model, the electrodeless load voltage regulator 7 is of a TSZ0-100KVA model, the injection transformer 8 is of an S11-M-500KVA model, the fault type judgment switching resistor 9 is of a ZN12-10 model, and the central processing unit 4 is of an STM32 model.
The control end of the central processing unit 4 is connected with the low-voltage side phase-selection switching switch cabinet 6, the electrodeless on-load voltage regulator 7, the fault type judging switching resistor 9 and the closed working cabinet where the controlled end of the vacuum circuit breaker 10 is located through a communication cable, and is used for controlling the actions of the low-voltage side phase-selection switching switch cabinet 6, the electrodeless on-load voltage regulator 7, the fault type judging switching resistor 9 and the vacuum circuit breaker 10.
Specifically, the central processing unit 4 monitors the neutral zero sequence voltage, when the zero sequence voltage is greater than 15% of the phase voltage, it is determined that a fault occurs, and the phase voltage is the lowest phase fault, then the central processing unit controls the switches K1 and K2 of the low-voltage side phase selection switching cabinet 6 to be connected with the phase fault of the terminal led out by the low-voltage side phase selection switching cabinet 6 in advance, and at the same time, the transformation ratio of the electrodeless on-load voltage regulator 7 is regulated to be the maximum, that is, the transformation ratio K is 1, the vacuum circuit breaker 10 is closed, the switch of the fault type judgment switching resistor 9 is 1, and at this time, the fault phase voltage is suppressed to 0, so that fault arc extinction is realized.
After fault arc extinction is realized, the fault type can be judged: the transformation ratio K of the electrodeless on-load voltage regulator 7 is reduced to be less than 1 by sliding the carbon brush of the electrodeless on-load voltage regulator 7, the switch 1 of the switching resistor 9 is judged by disconnecting the fault type, the switch of the switching resistor 9 is judged to be K2 or K3 by closing the fault type, the neutral point voltage is reduced, whether the zero sequence admittance phase angle of the power distribution network is changed or not is monitored, if the zero sequence admittance phase angle is not changed, the fault is judged to disappear, the switches and the carbon brush are restored to the original position, and the power distribution network is restored to normal operation; otherwise, the carbon brush is recovered until K is equal to 1, the switching resistors 9 to 1 are judged according to the fault types, arc extinction of the ground fault is continued, and fault processing is waited.
Specifically, the zigzag transformer is a common grounding transformer in a distribution network neutral point ungrounded system, and each phase is formed by connecting two groups of coils on different core legs. The common connection groups are ZNY11, ZNY1, ZNY11 in this embodiment, and other possible connection groups are not limited to inclusion. U shapeA1、UB1、UC1For the main winding voltage, U, on the high-voltage side of the zigzag transformerA2、UB2、UC2The winding voltage is shifted for the high-voltage side of the zigzag transformer. U shapea、Ub、UcFor three-phase voltage, k, on the low-voltage side of a zigzag transformerT1The transformation ratio of the high-voltage side and the low-voltage side of the zigzag transformer is obtained. U shapeAN、UBN、UCNThe voltage of the three-phase voltage of the power grid to the neutral point is obtained. Y is0For neutral grounded admittance, UY0Is the ground admittance voltage.
According to the winding of the zigzag transformer coil and the connection mode thereof, a vector relation diagram of three-phase voltages on the primary side of the zigzag transformer is obtained and is shown in fig. 4, and the relation diagram shows that the main winding voltage of the zigzag transformer is 30 degrees ahead of the voltage of a power distribution network, the voltage directions of the main winding and phase-shifting windings on the same iron core winding post of the zigzag transformer are opposite, and the phase voltage of the power distribution network is synthesized by the main winding and the phase-shifting winding voltage of the phase in which the main winding advances by 120 degrees.
The three-phase voltage on the low-voltage side of the Z-shaped grounding transformer is as follows: u shapea＝-kT1UA2，Ub＝-kT1UB2，Uc＝-kT1UC2；
When the A phase of the power distribution network has a ground fault, the primary side K of the electrodeless voltage regulator1The terminal is connected with a secondary side fault phase A phase terminal and K phase terminal of a zigzag transformer2The terminal is connected with the corresponding terminal of the zigzag transformer with secondary side fault phase advanced by 120 ℃, so that the voltage U of the low-voltage side of the electrodeless voltage regulatortct1Comprises the following steps:
Utct1＝-Ua+Uc＝-kT1(-U)A2+UC2
＝-kT1(U)A1+UC2＝-kT1UAN
high-voltage side U of electrodeless voltage regulatortct2Comprises the following steps:
Utct2＝-KkT1UAN
through injection transformer T3,Y0Upper voltage UY0Comprises the following steps:
UY0＝-KUAN
wherein, the transformation ratio of the injection transformer is 1/kT1。
Fault phase voltage UAComprises the following steps:
UA＝UY0+UAN
the transformation ratio of the electrodeless on-load voltage regulator is regulated and controlled to be maximum, namely the transformation ratio K is 1, the vacuum circuit breaker is closed, the fault type is judged that the switching resistor is closed to 1, the fault phase voltage is restrained to be close to 0 at the moment, and fault arc extinction is realized.
After the neutral point is suppressed to be zero for a period of time tau, the carbon brush of the electrodeless on-load voltage regulator is slid, and the transformation ratio is reduced to ensure that K is<1, disconnecting the fault type judging switching resistor switch 1, closing the fault type judging switching resistor switch to 2 or 3, and changing the neutral point voltage to-KMU due to resistance voltage divisionANWhere M is the coefficient of partial pressure.
The zero sequence parameters of the power distribution network are as follows:
wherein g is the power grid to ground electric conductivity, C is the power grid to ground capacitance, RfAnd a ground resistor for a fault point.
When the fault point does not disappear, the zero sequence parameter of the power distribution network can change along with the change of the voltage regulating coefficient K of the electrodeless voltage regulator and the voltage dividing coefficient M of the switching resistor. Judging whether the switch of the switching resistor is switched to 2 or 3 according to the fault type, changing the neutral point voltage, monitoring whether the zero sequence admittance phase angle of the power distribution network changes or not, if not, judging that the fault disappears, restoring each switch and carbon brush to the initial position, and restoring the normal operation of the power distribution network; otherwise, the carbon brush is recovered until K is equal to 1, the switching resistors 9 to 1 are judged according to the fault types, arc extinction of the ground fault is continued, and fault processing is waited.
The device can effectively inhibit arc light overvoltage, and the fault type can be judged through the electrodeless on-load voltage regulator and the fault type judging switching resistor of the regulating and controlling device. For instantaneous faults, the faults disappear by putting the arc extinction device, and the power distribution network recovers normal operation; for permanent faults, effective isolation can be achieved. The device control method has the advantages of simple structure and strong reliability, and is suitable for large-scale popularization and application.
In conclusion, the invention can effectively inhibit arc overvoltage, and the fault type can be judged through the electrodeless loaded voltage regulator and the fault type judging switching resistor of the regulating device. For instantaneous faults, the faults disappear by adjusting the low-voltage side phase-selection switching cabinet, the electrodeless on-load voltage regulator and the vacuum circuit breaker, and the power distribution network recovers to normal operation; for permanent faults, effective isolation can be achieved. The device control method has the advantages of simple structure and strong reliability, and is suitable for large-scale popularization and application.
The above disclosure is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or modifications within the technical scope of the present invention, and shall be covered by the scope of the present invention.
Claims (9)
1. The utility model provides a distribution network ground fault arc extinguishing device based on electrodeless pressure regulating which characterized in that includes:
the low-voltage side phase selection switching switch cabinet is connected with the low-voltage side of the zigzag transformer, and the high-voltage side of the zigzag transformer is connected with three phases of the power distribution network;
the input end of the electrodeless voltage regulator is connected with the switch wiring end of the low-voltage side phase-selection switching cabinet;
the input end of the injection transformer is connected with the output end of the electrodeless voltage regulator, and the output end of the injection transformer is grounded;
the grounding admittance is connected in parallel with the output end of the injection transformer;
one end of the fault type judging and switching resistor is connected with the output end of the injection transformer;
one end of the breaker is connected with the other end of the fault type judging switching resistor, and the other end of the breaker is connected with a neutral point led out from the high-voltage side of the zigzag transformer; and
and the central processing unit is respectively connected with the low-voltage side phase-selection switching switch cabinet, the electrodeless voltage regulator, the fault type judging switching resistor and the circuit breaker.
2. The electrodeless voltage regulation based power distribution network ground fault arc suppression device of claim 1, wherein the ratio of the meander transformer becomes kT1Then the transformation ratio of the injection transformer is 1/kT1。
3. The distribution network ground fault arc extinction device based on the electrodeless voltage regulation as claimed in claim 1, wherein if the zigzag transformer grounding mode is ZNY11, then a primary side K of the electrodeless voltage regulator is connected with a ground1Secondary side fault phase terminal of terminal connection zigzag transformer, secondary test K of non-polar voltage regulator2The terminal is connected with a corresponding terminal of the zigzag transformer secondary side with fault phase advanced by 120 degrees, and after voltage opposite to the fault phase is boosted, fault point electric arcs are restrained.
If the phase A has a ground fault, the voltage at the two ends of the injection transformer is as follows:
Uinj＝-KUAO
in the above formula, UinjIs the voltage injected into the high side of the transformer. K is the transformation ratio of the stepless voltage regulator, UAOIs the voltage of the distribution network a relative to the neutral point.
4. The distribution network ground fault arc extinction device based on the electrodeless voltage regulation as recited in claim 1, further comprising a closed work cabinet and an outdoor protection shell,
the closed working cabinet is used for placing a low-voltage side phase-selection switching switch cabinet, a non-polar voltage regulator, an injection transformer, a fault type judging switching resistor, a circuit breaker and a central processing unit;
the outdoor protective shell is used for placing the closed working cabinet.
5. The distribution network ground fault arc extinction device based on electrodeless voltage regulation as claimed in claim 6, wherein one of the closed work cabinets is used for installing a low-voltage side phase-selection switching cabinet, an electrodeless voltage regulator, an injection transformer, a fault type judgment switching resistor, a circuit breaker or a central processing unit.
6. An arc extinction method for power distribution network ground faults based on electrodeless voltage regulation, which applies the arc extinction device for power distribution network ground faults based on electrodeless voltage regulation of claims 1-5, and is characterized by comprising the following steps:
the distribution network ground fault arc extinction device based on the electrodeless voltage regulation obtains voltage suppression neutral point voltage opposite to a fault by using the low-voltage side voltage of the zigzag transformer, and quickly switches the neutral point series resistor to quickly judge whether the fault point disappears.
7. The distribution network ground fault arc extinction method based on the electrodeless voltage regulation as claimed in claim 1, wherein the distribution network ground fault arc extinction device based on the electrodeless voltage regulation obtains a voltage suppression neutral point voltage opposite to the fault by using a low-voltage side voltage of a zigzag transformer, and rapidly switches a neutral point series resistor to rapidly judge whether the fault point disappears, specifically comprising:
the method comprises the steps that a central processing unit monitors neutral point voltage, when zero sequence voltage of a neutral point is larger than a phase voltage threshold value, a fault of a distributed single network is judged, and a fault phase with the lowest phase voltage is judged;
the switch of the low-voltage side phase-selecting switching switch cabinet is controlled to be connected with a terminal fault phase led out by the low-voltage side phase-selecting switching switch cabinet in advance, the transformation ratio of the electrodeless on-load voltage regulator is adjusted to be maximum, the injection transformer is boosted, the vacuum circuit breaker is set to be closed, the switch of the fault type judging switching resistor is connected with a non-resistance end, the voltage of the fault phase is suppressed to 0, and the arc extinction of the fault is realized.
8. The distribution network ground fault arc extinction method based on the electrodeless voltage regulation as claimed in claim 1, wherein whether a fault point disappears is rapidly judged, and specifically includes:
sliding a carbon brush of the electrodeless voltage regulator, reducing the transformation ratio K <1 of the electrodeless voltage regulator, disconnecting a switch 1 of the fault type judging switching resistor, closing the switch of the fault type judging switching resistor to K2 or K3, and reducing the neutral point voltage; monitoring whether a zero sequence admittance phase angle of the power distribution network changes, if not, judging that the fault disappears, restoring each switch and the carbon brush to the original position, and restoring the normal operation of the power distribution network; and otherwise, recovering the carbon brush until K is equal to 1, judging the fault type to 1 by the switching resistor, continuing to perform arc extinction of the ground fault, and waiting for fault treatment.
9. The method for eliminating the ground fault of the distribution network based on the electrodeless voltage regulation as recited in claim 7, wherein the impedance of the zero sequence voltage of the neutral point is as follows:
in the above formula, g is the ground conductance of the distribution network, and C is the distributionThe network-to-ground capacitance, M is the voltage division coefficient of the neutral point after the resistor is switched, K is the transformation ratio of the electrodeless voltage regulator, and RfIs the fault point ground impedance.
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