CN114325468A - Method for conducting grounding phase selection and line selection by utilizing 66kV active intervention arc suppression device - Google Patents
Method for conducting grounding phase selection and line selection by utilizing 66kV active intervention arc suppression device Download PDFInfo
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Abstract
The invention discloses a grounding phase selection and line selection method for a 66kV active intervention arc suppression device, which can accurately and quickly determine a fault line so as to improve the power supply safety, reliability and economy of a 66kV system. The method comprises the following steps: sampling data and carrying out zero sequence increment starting, line and phase voltage calculation and analysis, S3 carrying out steady-state grounding phase selection by using zero sequence voltage mode angle comparison, slope calculation and comparison and single-phase grounding line selection based on a rapid switch type arc extinction and resonance elimination device.
Description
Technical Field
The invention relates to the field of relay protection, in particular to a method for conducting grounding phase selection and line selection by utilizing a 66kV active intervention arc suppression device.
Background
The 66kV voltage class power grid is an important component of a national power system and is a bridge for connecting a power transmission system and power consumers, and the safe and stable operation of the 66kV system is directly related to the benefits of the power consumers. According to statistics, more than 95% of power failure accidents suffered by power consumers are caused by the reasons of a power distribution system, and more than 85% of faults of a 66kV system are single-phase earth faults. The 66kV system in China adopts a low-current grounding mode that a neutral point is not directly grounded, the probability of single-phase grounding faults of the 66kV system is far higher than that of two-phase short-circuit faults, and due to the low-current grounding mode, three line voltages are still symmetrical when the 66kV system is grounded in a single phase, power supply is not affected, and the single-phase grounding can run for 1-2 hours according to the regulation of the safety regulations of power systems. However, with the continuous progress of social economy, the power load is continuously increased, the urban scale is continuously enlarged, the number of outgoing cables is increased, the 66kV system network is increasingly huge, and the grounding current of a 66kV transformer substation is increased. According to the regulation, the single-phase grounding current exceeds 30A, and single-phase grounding protection equipment needs to be installed. Because the 66kV system directly serves the masses and is close to the living places of people, personal electric shock accidents of a high-voltage power grid often occur. The importance of ensuring the power supply safety and the reliable operation of the 66kV system is very prominent in order to ensure the safety of human life and property, quickly and accurately eliminate the 66kV system fault.
At present, 66kV systems at home and abroad mainly adopt a mode that a neutral point is grounded through an arc suppression coil and the neutral point is grounded through a resistor. The arc suppression coil grounding mode has the long-time single-phase fault point operation characteristic, represents a good surface capable of supplying power uninterruptedly to a user, and leaves a plurality of problems difficult to solve for the safe operation of the system:
(1) if single-phase earth faults occur due to electric shock of people and animals, the lines cannot be rapidly powered off, people and animals cannot be effectively protected, and the electric shock time is prolonged, so that serious injury accidents are caused.
(2) The neutral point ungrounded system has no arc quenching measures, the neutral point can only compensate the power frequency reactive component in the grounding current through the arc suppression coil in the arc suppression coil grounding system, the power frequency active component and the high frequency component in the grounding current cannot be compensated, and the arc quenching effect is limited. Once an arc is generated, an arc overvoltage is caused, and a power grid cascading failure is caused. Meanwhile, the electric arc can cause accidents such as fire and the like, and great loss is caused to a power grid and users.
(3) At present, as the length of an overhead line is increased and a cable line is increased, the system capacitance current is increased, and when the capacitance current is increased to a certain degree, the manufacture of an arc suppression coil is very difficult and the cost is too high. In order to solve the problem, the 66kV system in China changes the grounding mode of a neutral point into grounding through a small resistor, so that the advantage of high power supply reliability of the non-effective grounding mode of the neutral point is sacrificed.
(4) At present, the problems of single-phase earth fault line selection and fault location of a 66kV system are not well solved, fault line selection is carried out on a plurality of substations through a manual line pulling method, fault location is carried out through a manual line patrol method, power failure time is prolonged, risk of operation with faults is increased, and power supply reliability is also reduced.
In addition, the neutral point is grounded through a resistor, and the method has certain problems:
(1) the neutral point can not guarantee the reliability of power supply by short-time fault operation after being grounded through a low resistor, but the reliability of power supply is improved by strengthening the structure of a power grid and improving the automation level;
(2) because the current of the grounding point is large, if the zero sequence protection is not timely, the grounding point and the nearby insulation are more damaged, and the tripping times of the permanent and non-permanent single-phase grounding line of the interphase fault of the cable line are obviously increased. Especially, the human body is induced with electricity, the grounding current is increased, and the injury degree is increased.
The line selection accuracy is not high for various reasons. In addition, the grounding mode of a fault phase through a low-impedance transformer is adopted, so that the grounding current of the system is completely transferred to a protective grounding point when the system is in protective grounding, and the grounding line selection device made by different line selection principles can further reduce the line selection performance and even lose the function because the multiple judgment conditions cannot be met.
In order to solve the problems, a 66kV active intervention arc suppression device is available in the market and comprises a primary grounding protection cabinet, a secondary control screen, a signal generator and a handheld signal receiving device, wherein the primary grounding protection cabinet comprises a single-phase circuit breaker, a low-impedance transformer and a zero-sequence current transformer; the secondary control screen comprises a single-phase grounding phase selection control unit, a grounding line selection unit and a driving locking module; however, the current device still cannot ensure the accuracy of fault phase selection, and the effect is poor in application.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a grounding phase selection line selection method of a 66kV active intervention arc suppression device based on a low excitation impedance transformer on the premise of not changing the advantages of a neutral point non-effective grounding mode, so that a fault line can be accurately and quickly determined, and the power supply safety, reliability and economy of a 66kV system are improved.
The technical scheme of the invention is as follows: a method for fault line selection by using a 66kV active intervention arc suppression device is characterized by comprising the following steps:
s1 sampling data and performing zero sequence incremental starting
Acquiring a bus phase, a line voltage and a zero sequence voltage of a substation in real time, carrying out vector operation on the zero sequence voltage, and starting grounding phase judgment when a variation value exceeds a set limit value;
s2 line and phase voltage calculation and analysis
Suppose K point A phase transition resistance RgGrounding, connecting K-point A-phase positive sequence, negative sequence and zero sequence networks in series and then short-circuiting to form a composite sequence network, and connecting zero sequence voltage on a bus M
Zero sequence voltage to fault point K
Equality, namely zero sequence voltage in the power grid is equal everywhere and is irrelevant to the position of a fault point; bus M available from composite grid
Is composed of
Wherein XC∑See formula (2-1), rewriting the above formula to
Wherein θ -angle, θ ═ arctg (3 ω R)gC0∑) When R isgWhen changing from 0 to infinity, θ is 0 to 90 °, and 2 θ is 0 to 180 °;
can be seen from the formula (1-2)
Trace of endpoint is
The end point is the center of a circle
Establishing phase A through R for a clockwise half arc of radiusgThe vector relationship diagram of zero sequence voltage and transition resistance Rs when grounded can be seen: namely RgWhen the temperature is changed from 0 to infinity,
the end points change along the semi-circle in the figure according to the direction of the arrow; when R isgWhen the grounding is 0, i.e. metallic grounding, then
So that the three-phase voltages are respectively
It can be seen that when the single-phase grounding is carried out, the power grid has higher zero sequence voltage, and the zero sequence voltage close to 100V can be detected at the triangular side of the opening of the voltage transformer; at the same time, the non-faulted phase voltage rises
Doubling;
As can be seen from the phase voltage phasor relation diagram of the power grid
In an asymmetrical state, and line voltage
Still in a symmetrical state;
s3 steady-state grounding phase selection by zero-sequence voltage mode angle comparison
S3.1, zero sequence voltage angle comparison: comparing and prejudging the grounding phase by using a zero sequence voltage phase angle, wherein the phase of U0 is grounded for A phase between 180 and 270 degrees; the phase of U0 is grounded for B phase between 60-150 degrees; the phase of U0 is grounded for C phase between 30-60 degrees;
s3.2, comparing the zero sequence voltage mode angles:
s4 slope calculation and comparison
When the mode angle comparison condition is not met, selecting the phase of intermittent grounding through slope change, and controlling the corresponding phase single-phase circuit breaker to switch on when the slope change is steep and is a fault phase through a recording graph;
s5 single-phase grounding line selection based on quick switch type arc and harmonic elimination device
S5.1 analysis of current distribution characteristics of grounding capacitor in unprotected grounding
When the system is in single-phase grounding, the grounding current of the non-fault loop is recorded as Ifo', is self-to-ground capacitance current IoZ' the direction flows from the bus to the line, then: i isfo’＝IoZThe relationship of'; the grounding current of the fault loop is recorded as Igo', is self-to-ground capacitance current Ioz', the direction is from bus to line, and a full-network grounding capacitance current IJ' the direction from the fault phase to the bus bar is Igo’＝Ioz’-IJThe relationship of';
s5.2 ground capacitance current distribution and characteristic analysis during protection grounding
When the protection is grounded: the grounding current of the non-fault loop is recorded as Ifo", it is still the capacitance current to earth itself, since it becomes the steady metallic grounding, the amplitude changes correspondingly, it is marked as Ioz", the degree of grounding is denoted as U0", then there is Ifo”＝IoZ"in the same manner as above; the grounding current of the fault loop is recorded as Igo", since the return current on the fault phase tends to 0, only the self capacitance-to-ground current is left, which is marked as Ioz", then there is Igo”＝I”oz；
S5.3 zero sequence current characteristic equation line selection
From the above analysis results, when the system is grounded and protected to be grounded, the grounding current of the non-fault loop is the self-grounding capacitance current, and the magnitude of the grounding current is irrelevant to the grounding position, only relevant to the grounding degree, and has the advantages of
And (3) deriving a zero-sequence current characteristic equation:
wherein UO 'and IO' are zero sequence voltage and zero sequence current of the line when grounding, and UO 'and IO' are zero sequence voltage and zero sequence current of the line when grounding transfer;
and (3) recording waves before and after the action of the split-phase circuit breaker by adopting a grounding line selection unit, and determining a grounding fault line by adopting a zero-sequence current characteristic equation according to the change of zero-sequence current of each line before and after the switch-on of the split-phase circuit breaker.
Furthermore, the grounding phase selection device comprises a display communication module, an acquisition and calculation module and a driving locking module, wherein the acquisition and calculation module adopts a TMS320F2812DSP signal processor as an operation CPU, a 14-bit A/D analog-to-digital conversion chip AD7865 performs analog-to-digital conversion to complete signal acquisition of zero sequence voltage and system phase line voltage, the signal processor performs analysis and calculation to judge single-phase grounding faults and identify grounding phases, corresponding relays are opened to control the action of the single-phase circuit breakers, and calculation data and action waveforms are uploaded to the display communication module through a double-port RAM 7024.
Furthermore, the sampling speed of the DSP signal processor is 320-640 times/cycle, and the zero sequence current and the system zero sequence voltage of each loop before and after the split-phase circuit breaker acts are synchronously sampled, so that the synchronism of each signal is ensured.
Furthermore, the driving locking module comprises a metal-oxide-semiconductor field effect transistor (MOSFET), a quick phase selection relay DZK-1, relay contacts J2, J3 and A which are locked with each other, a quick phase selection relay DZK-2, relay contacts J3, J1 and B which are locked with each other, a quick phase selection relay DZK-3, relay contacts J1, J2 and C which are locked with each other, only one phase selection relay is closed at any time, and only one phase selection relay is opened at any time; the nodes of the single-phase circuit breaker are mutually locked, one phase is switched on, and other single-phase circuit breaker switching-on loops are disconnected, so that the condition that two phases are not switched on at any moment is ensured.
The invention adopts the steady-state grounding technology to solve the problem of no protection of intermittent grounding overvoltage; the problem of grounding phase selection is solved by adopting a zero sequence voltage and line voltage mode angle comparison technology; the method solves the problem of grounding and line selection precision by adopting a zero sequence current characteristic equation method, is not influenced by factors such as system operation mode, line properties, geographical conditions, grounding degree, fault indicator measurement precision, installation interval distance, CT error and the like, realizes accurate line selection for researching and developing a single-phase grounding comprehensive protection device of a power distribution network, can avoid system overvoltage caused by intermittent grounding and damage of interphase short circuit fault caused by single-phase grounding, simultaneously realizes automatic identification of grounding fault, is convenient for maintenance personnel to quickly position grounding fault points, and has important significance for ensuring safety production, reliable power supply and life safety of social masses of power enterprises.
Drawings
Fig. 1 is a circuit diagram of phase a ground of the present invention;
FIG. 2 is a schematic diagram of a zero sequence network when K point is grounded in a power grid;
FIG. 3 is a schematic diagram of a composite grid with phase A grounded at point K;
FIG. 4 shows phase A passing through RgA schematic diagram of zero sequence voltage change when grounded;
FIG. 5 shows phase A passing through RgA neutral point displacement diagram when grounded;
FIG. 6 is a schematic circuit diagram of a 66kV active intervention arc suppression device;
FIG. 7 is a block diagram of a sample computation unit circuit;
FIG. 8 is a schematic circuit diagram of a drive latch module;
FIG. 9 is a control flow diagram of the present invention;
FIG. 10 is a schematic diagram of intermittent grounded recording;
fig. 11 is a circuit block diagram of a ground line selection unit.
Detailed Description
As shown in fig. 6, 7, 8 and 11, the fast switching arc and resonance extinction and elimination device according to the present invention includes a primary grounding protection cabinet, a secondary control panel, a signal generator 4 and a handheld signal receiving device 7, wherein the primary grounding protection cabinet includes a single-phase circuit breaker 2, a low impedance transformer 3 and a zero sequence current transformer 5; the secondary control screen 1 comprises a single-phase grounding phase selection control unit, a grounding line selection unit and a driving locking module, adopts a high-speed signal processor DSP, adopts multi-channel synchronous sampling, has the sampling speed of 640 times/cycle, synchronously samples zero-sequence current and system zero-sequence voltage of each loop before and after the action of the phase-splitting circuit breaker, and ensures the synchronism of each signal. By utilizing the characteristic that the zero-sequence current of a fault circuit can change before and after the unique action of the automatic split-phase grounding protection device, a characteristic equation method is created for line selection, and the fault grounding circuit can be accurately selected.
The secondary control screen 1 is composed of a single-phase grounding phase selection control unit, a grounding line selection unit and a driving locking module, is a core part of the rapid switch type arc and harmonic elimination device, and realizes functions of grounding phase selection, line selection, fault phase impedance measurement and the like.
One end of the single-phase circuit breaker 2(K1, K2 and K3) is connected with a substation bus, and the other end is connected with a ground grid 6 through a low impedance transformer 3. The system is in a switching-off state during normal operation, is in a switching-on state during ground protection, forces a fault phase to have equal potential with the ground, realizes electrical and program locking between the fault phase and the ground by driving the locking module, and only allows a one-phase breaker to be switched on under any condition.
The low impedance transformer 3 consists of three coils, wherein W1 is a primary coil, one end of the primary coil is connected with the split-phase circuit breaker, and the other end of the primary coil is connected with the ground grid 6; w2 is secondary coil of reactance transformer, which is connected with single-phase grounding protection control unit for signal measurement; w3 is a primary and secondary coil of a reactance type transformer, and is connected to a signal generator 4 as a high frequency signal power source for coupling a high frequency signal. And the signal generator 4 injects a special frequency signal into the system according to the instruction of the single-phase grounding control unit, and is used for fault positioning and fault automatic resetting. The equipment is specially-made equipment capable of working by a double-frequency power supply, is an electric reactor at power frequency, has impedance less than 1 ohm, and is mainly used for arc extinction and overvoltage protection; the transformer is used at high frequency and is mainly used for injecting high-frequency voltage into a fault phase under the condition of ensuring that the device can effectively protect the fault phase.
And the zero sequence current transformer 5 is arranged on a connecting line between the device and the grounding grid and is used for measuring the grounding current flowing through the device.
The grounding grid 6 determines the effect of grounding protection, and the device is required to be well connected with the grounding grid, so that grounding impedance is reduced as much as possible.
The handheld signal receiving device 7 can detect a special frequency signal which is injected into the system by the signal generator 4 through the low impedance transformer 3, and is used for an operator to carry out line patrol and locate faults.
The grounding phase selection control unit adopts a 4u case and consists of three modules, which are respectively as follows: the device comprises a display communication module, an acquisition and calculation module and a driving locking module. And each module exchanges data through the double-port RAM, and the anti-interference performance is enhanced by adopting a rear plug board mode.
The sampling calculation module adopts a TMS320F2812DSP signal processor as a calculation CPU, a 14-bit A/D analog-to-digital conversion chip AD7865 carries out analog-to-digital conversion to finish signal acquisition of zero sequence voltage and system phase line voltage, the DSP signal processor carries out analysis calculation to judge single-phase earth faults and identify an earth phase, a corresponding relay is opened to control the action of a single-phase circuit breaker, and calculation data and action waveforms are uploaded to the display communication module through a double-port RAM 7024.
The main technical indexes are as follows:
the sampling channels are 8: three line voltages of zero sequence voltage, zero sequence current, three phase voltages of Ua, Ub and Uc, and three line voltages of Uab, Ubc and Uca are respectively adopted;
sampling frequency: 320 times per cycle;
signal measurement range: the voltage is 0-100 VAC, and the current is 0-6A;
the driving locking module completes the driving of the single-phase circuit breaker and locks the driving circuit, so that the phenomenon that two phases are simultaneously closed at any moment is avoided.
The single-phase circuit breaker adopted by the device is a vacuum permanent magnet mechanism, the operating current of the single-phase circuit breaker is about 25A, and the operating speed is only 40ms, so that a voltage-driven electronic switching device MOSFET with lower power is adopted to form a driving loop. In order to ensure the action accuracy and avoid false action, the whole driving part is locked in a triple mode: 1) only one path of MOSFET is designed on the driving locking module, so that simultaneous driving output is avoided; 2) at the rear stage of the driving circuit, a quick phase selection relay is used, the relay contacts are locked with each other, only one phase selection relay is closed at any time, and only one phase selection relay is opened at any time; 3) the nodes of the single-phase circuit breaker are mutually locked, one phase is switched on, and other single-phase circuit breaker switching-on loops are disconnected, so that the condition that two phases are not switched on at any moment is ensured. DZK-1, DZK-2 and DZK-3 in FIG. 8 are A, B, C phase selection relays respectively, and J1, J2 and J3 are single-phase breaker position relays.
The working process is as follows:
the secondary control screen 1 collects the phase of a bus, the line voltage and the zero sequence voltage of a substation in real time, whether a system has a single-phase earth fault and the phase of the earth is judged according to the mode angle change of the zero sequence voltage and the line voltage, when the single-phase earth fault occurs, the single-phase circuit breakers 2(K1, K2 and K3) of corresponding phases are controlled to be switched on rapidly, after the corresponding phase circuit breakers are switched on, the faults are forced to be equipotential relatively, the earth arc is extinguished, meanwhile, effective protection is provided for human body electricity sensing, and the occurrence of personal injury accidents is avoided. When the grounding property is intermittent grounding, the device can convert unstable grounding into stable metal grounding, so that intermittent overvoltage is avoided.
And the grounding line selection unit records waves before and after the action of the split-phase circuit breaker, and determines a grounding fault line by adopting a zero-sequence current characteristic equation according to the change of zero-sequence current of each line before and after the switch-on of the split-phase circuit breaker.
After the single-phase circuit breaker 2 is switched on, after a set time delay, a signal generator 4 is started, special frequency voltage is injected into a system through a primary secondary coil W3 of a low-impedance transformer connected with the signal generator 4 to generate grounding current, a grounding phase selection control unit collects voltage and current signals fed back by a secondary coil W2 of the low-impedance transformer to separate the injected special frequency signals, the change of the grounding impedance of the system is calculated, if the grounding impedance is recovered to a normal state of the system, the grounding fault is judged to disappear, the grounding phase selection control unit controls the switching-off of the single-phase circuit breaker 2(K1, K2 and K3), and the automatic resetting of the single-phase grounding fault is realized. If the earth fault can not be recovered for a long time, an operator holds the handheld signal receiving device to patrol along a fault loop selected by the earth line selection unit, a fault point is searched, and the handheld signal receiving device displays that the received signal is weakened from strong, namely the fault point, so that the single-phase earth fault positioning is completed.
The grounding phase selection control unit collects zero sequence voltage, three-phase voltage of a bus A, B, C, three line voltages UAB, UBC, UCA and zero sequence current, the zero sequence voltage touch angle comparison technology is adopted to judge single-phase grounding faults and identify grounding fault phases, and the corresponding phase single-phase circuit breakers are controlled to be switched on, so that the single-phase grounding protection function is realized.
The control flow of the present invention is shown in fig. 9, and specifically as follows:
1) s1 sampling data and performing zero sequence incremental starting
The method comprises the steps of collecting a bus phase, a line voltage and a zero sequence voltage of a substation in real time, adopting a zero sequence voltage increment starting mode to carry out vector operation on the zero sequence voltage in order to ensure the sensitivity and the starting speed of grounding phase selection, starting grounding phase judgment when a variation value exceeds a set limit value, improving starting sensitivity, and avoiding the possibility of misoperation caused by the zero sequence voltage generated by system unbalance.
The hardware selection of the grounding line selection unit and the hardware selection of the grounding phase selection unit adopt the same mode, a display communication module is constructed by a PC104 structure 486 host computer, and a TMS320F2812DSP signal processor and an AD7865 analog-to-digital conversion chip form a sampling module. The same starting signal mode is used by multiple sampling modules, and a signal output by the grounding phase selection control unit is used as a starting signal, so that synchronous wave recording of each sampling module is ensured.
2. Calculation and analysis of steady-state grounding time line and phase voltage
A-phase transit resistance R at K point of line K in FIG. 1gAnd grounding, and connecting the positive sequence, negative sequence and zero sequence networks of the phase A at the point K in series to form a composite sequence network. Because the neutral point of the power grid is not grounded and the grounding current is not large, the positive sequence, negative sequence and zero sequence impedances of the transformer T and the lines L1 and L2 … in the figure 2 can be ignored, and then Z of the K point∑1＝0、Z∑2The zero sequence network is shown in fig. 2, and the composite sequence network is shown in fig. 3.
As can be seen from FIG. 3, the zero sequence voltage on the bus M
Zero sequence voltage to fault point K
Equality, i.e. zero sequence voltage in the grid is equal everywhere, independent of the location of the fault point. Bus M available from composite grid
Is composed of
Wherein XC∑See formula (2-1), rewriting the above formula to
Wherein θ -angle, θ ═ arctg (3 ω R)gC0∑) When R isgWhen changing from 0 to infinity, θ is 0 to 90 °, and 2 θ is 0 to 180 °.
Can be seen from the formula (2)
Trace of endpoint is
The end point is the center of a circle
Is a clockwise half arc of a radius as shown in fig. 4. Namely RgWhen the temperature is changed from 0 to infinity,
the end points vary in the direction of the arrows along the semi-circle in the figure. When R isgWhen the metal ground is equal to 0 (metallic ground),
is provided with
So that the three-phase voltages are respectively
It can be seen that when the single-phase grounding is carried out, the power grid has higher zero sequence voltage, and the voltage transformer has three openingsZero sequence voltage close to 100V can be detected by the angular side; at the same time, the non-faulted phase voltage rises
And (4) doubling.
Respectively electromotive force with power supply
Equal, middle neutral point shift electromotive force
When the voltage is expressed, the voltage of the power grid phase
Is shown as
Making phasor relationships is shown in fig. 5. It can be seen that the three-phase voltage
In an asymmetrical state, and line voltage
Still in a symmetrical state.
Steady-state grounding phase selection for S3 zero-sequence voltage mode angle comparison
And S3, when single-phase grounding occurs, the grounding phase voltage is reduced, and the non-fault phase voltage is increased, and as can be seen from the graph 5, when the 2 theta is larger, namely the grounding is performed through a larger transition resistor, the grounding phase voltage is not the lowest. In extreme cases, such as metallic grounding, two phases of voltages are the same, and meanwhile, the distribution network is affected by other non-single-phase grounding factors, so that the change of zero sequence voltage and phase voltage is caused, and the problem of selecting wrong grounding phase is caused.
By analyzing the change characteristics of the zero sequence voltage during steady-state grounding, the zero sequence voltage
Trace of endpoint is
The end point is the center of a circle
Is a clockwise half arc of a radius.
The phase ground is the ground-to-ground voltage. And determining a phase selection method for comparing the zero sequence voltage mode angles.
1) And (3) zero-sequence voltage angle comparison: comparing the phase of the pre-judged grounding phase U0 by using the phase angle of the zero sequence voltage to be in the range of 180-270 to be grounding of phase A; the phase U0 is grounded for the phase B between 60 and 150; the phase of U0 is C-phase grounding between 30-60.
S3.2) zero sequence voltage mode comparison: determining phase of ground
The application proves that the grounding phase selection accuracy is 100%, and the grounding phase can be accurately selected by the zero sequence voltage variation of 0.3v in actual measurement.
S4 slope calculation and comparison
As can be seen from fig. 10, the intermittent grounding is generally caused by insulation breakdown, insulation is not broken down when the voltage is low, all the system is normal, when the voltage is increased to a certain value, insulation breakdown occurs, the grounding phase voltage is 0, zero sequence voltage occurs, zero sequence change does not conform to the touch angle change rule, but the phase voltage changes suddenly, and thus, a phase selection method with slope change is designed. When the mode angle comparison condition is not met, selecting the phase of intermittent grounding through slope change, and controlling the corresponding phase single-phase circuit breaker to switch on when the slope change is steep and is a fault phase through a recording graph;
s5 single-phase grounding line selection based on quick switch type arc and harmonic elimination device
S5.1 analysis of current distribution characteristics of grounding capacitor in unprotected grounding
When the system is in single-phase grounding, the current distribution situation of the grounding capacitor can be known as follows:
1) the grounding current of the non-fault loop is recorded as Ifo', is self-to-ground capacitance current IoZ' the direction flows from the bus to the line, then: i isfo’＝IoZ' of the formula (I).
2) The grounding current of the fault loop is recorded as Igo', is self-to-ground capacitance current Ioz', the direction is from bus to line, and a full-network grounding capacitance current IJ' the direction from the fault phase to the bus bar is Igo’＝Ioz’-IJ' of the formula (I).
S5.2 ground capacitance current distribution and characteristic analysis during protection grounding
When the protection is grounded:
1) the grounding current of the non-fault loop is recorded as Ifo", still self capacitance-to-ground current, due to change to steady-state metallicGrounding, corresponding change in amplitude, denoted as Ioz", the degree of grounding is denoted as U0", then there is Ifo”＝IoZ"is used in the following description.
2) The grounding current of the fault loop is recorded as Igo", since the return current on the fault phase tends to 0, only the self capacitance-to-ground current is left, which is marked as Ioz", then there is Igo”＝I”oz
S5.3 zero sequence current characteristic equation line selection
It can be easily seen from the above analysis results that when the system is grounded and protected to be grounded, the grounding current of the non-fault loop is the self-grounding capacitance current, the magnitude of the grounding current is irrelevant to the grounding position and only relevant to the grounding degree, and a zero-sequence current characteristic equation is derived:
the function expression established is shown as the following formula:
(U0"/U0'× I0' -I0") → 0 non-faulted lines;
wherein UO 'and IO' are zero sequence voltage and zero sequence current of the line when grounding, and UO 'and IO' are zero sequence voltage and zero sequence current of the line when grounding transfer;
the line selection method is not influenced by factors such as a system operation mode, a grounding degree and CT errors, and provides a main theoretical basis for researching and developing a single-phase grounding comprehensive protection device of a power distribution network and realizing accurate line selection.
A high-speed signal processor DSP is adopted, multi-channel synchronous sampling is carried out, the sampling speed reaches 640 times/cycle, the zero sequence current of each loop and the zero sequence voltage of a system before and after the action of the split-phase circuit breaker are synchronously sampled, and the synchronism of each signal is ensured. By utilizing the characteristic that the zero-sequence current of a fault circuit can change before and after the unique action of the automatic split-phase grounding protection device, a characteristic equation method is created for line selection, and the fault grounding circuit can be accurately selected.
Under the effective protection state, the zero sequence voltage is the maximum value of the system, and at the moment, if the fault disappears, the system cannot judge according to the change of the zero sequence voltage; meanwhile, the split-phase protection device has obvious protection effect, and no obvious trace exists at a fault point, so that difficulty is brought to inspection personnel to determine the fault point. The existing single-phase earth fault positioning technology is generally implemented in a power failure or no effective protection state, and fault positioning in the single-phase earth protection state is in a blank state.
The software function design of the grounding line selection unit adopts a mode that a sampling calculation module is responsible for synchronous real-time sampling and a display communication module is responsible for line selection calculation. The grounding line selection algorithm adopts a line selection method of a zero sequence current transfer characteristic equation according to the action characteristics of the rapid switch type arc and resonance extinction device, namely when a grounding fault occurs, the direction of the zero sequence current of a grounding loop is the line flow direction bus, and the zero sequence current value is the sum of the zero sequence currents of a non-grounding loop of the system; after the device acts and the grounding is transferred, the zero sequence current of the grounding loop can obviously change in direction and amplitude.
Since the grounding line selection algorithm is to compare zero sequence currents before and after grounding protection, the accuracy of grounding time judgment is very important. The zero sequence current starting judgment method is adopted for judging the grounding moment, when the device is protected, the grounding current of the transfer system flows through the device, and the grounding transfer moment can be accurately judged according to the judgment of the zero sequence CT measurement signal of the device. And finding out the grounding loop with the maximum change by comparing the change of the zero sequence current of each loop before and after the grounding transfer.
Claims (4)
1. A method for fault line selection by using a 66kV active intervention arc suppression device is characterized by comprising the following steps:
s1 sampling data and performing zero sequence incremental starting
Acquiring a bus phase, a line voltage and a zero sequence voltage of a substation in real time, carrying out vector operation on the zero sequence voltage, and starting grounding phase judgment when a variation value exceeds a set limit value;
s2 line and phase voltage calculation and analysis
Suppose K point A phase transition resistance RgGrounding, connecting K points A phase positive sequence, negative sequence and zero sequence networks in series and then short-circuiting to form a complexSequencing network, zero sequence voltage on bus M
Zero sequence voltage to fault point K
Equality, namely zero sequence voltage in the power grid is equal everywhere and is irrelevant to the position of a fault point; bus M available from composite grid
Is composed of
Wherein XC∑See formula (2-1), rewriting the above formula to
Wherein θ -angle, θ ═ arctg (3 ω R)gC0∑) When R isgWhen changing from 0 to infinity, θ is 0 to 90 °, and 2 θ is 0 to 180 °;
can be seen from the formula (1-2)
Trace of endpoint is
The end point is the center of a circle
Establishing phase A through R for a clockwise half arc of radiusgThe vector relationship diagram of zero sequence voltage and transition resistance Rs when grounded can be seen: namely RgWhen the temperature is changed from 0 to infinity,
the end points change along the semi-circle in the figure according to the direction of the arrow; when R isgWhen the grounding is 0, i.e. metallic grounding, then
So that the three-phase voltages are respectively
It can be seen that when the single-phase grounding is carried out, the power grid has higher zero sequence voltage, and the zero sequence voltage close to 100V can be detected at the triangular side of the opening of the voltage transformer; at the same time, the non-faulted phase voltage rises
Doubling;
As can be seen from the phase voltage phasor relation diagram of the power grid
In an asymmetrical state, and line voltage
Still in a symmetrical state;
s3 steady-state grounding phase selection by zero-sequence voltage mode angle comparison
S3.1, zero sequence voltage angle comparison: comparing the phase angle of zero sequence voltage to pre-judge the phase difference of ground,
the phase of U0 is grounded for phase A between 180 DEG and 270 DEG; the phase of U0 is grounded for B phase between 60-150 degrees; the phase of U0 is grounded for C phase between 30-60 degrees;
s3.2, comparing zero sequence voltage modes:
s4 slope calculation and comparison
When the mode angle comparison condition is not met, selecting the phase of intermittent grounding through slope change, and controlling the corresponding phase single-phase circuit breaker to switch on when the slope change is steep and is a fault phase through a recording graph;
s5 single-phase grounding line selection based on quick switch type arc and harmonic elimination device
S5.1 analysis of current distribution characteristics of grounding capacitor in unprotected grounding
When the system is in single-phase grounding, the grounding current of the non-fault loop is recorded as Ifo', is self-to-ground capacitance current IoZ' the direction flows from the bus to the line, then: i isfo’＝IoZThe relationship of'; the grounding current of the fault loop is recorded as Igo', is self-to-ground capacitance current Ioz', the direction is from bus to line, and a full-network grounding capacitance current IJ' the direction from the fault phase to the bus bar is Igo’＝Ioz’-IJThe relationship of';
s5.2 ground capacitance current distribution and characteristic analysis during protection grounding
When the protection is grounded: the grounding current of the non-fault loop is recorded as Ifo", it is still the capacitance current to earth itself, since it becomes the steady metallic grounding, the amplitude changes correspondingly, it is marked as Ioz", the degree of grounding is denoted as U0", then there is Ifo”＝IoZ"in the same manner as above; the grounding current of the fault loop is recorded as Igo", since the return current on the fault phase tends to 0, only the self capacitance-to-ground current is left, which is marked as Ioz", then there is Igo”＝I”oz；
S5.3 zero sequence current characteristic equation line selection
From the above analysis results, when the system is grounded and protected to be grounded, the grounding current of the non-fault loop is the self-grounding capacitance current, and the magnitude of the grounding current is irrelevant to the grounding position and only relevant to the grounding processIs highly correlated and has
And (3) deriving a zero-sequence current characteristic equation:
wherein UO 'and IO' are zero sequence voltage and zero sequence current of the line when grounding, and UO 'and IO' are zero sequence voltage and zero sequence current of the line when grounding transfer;
and (3) recording waves before and after the action of the split-phase circuit breaker by adopting a grounding line selection unit, and determining a grounding fault line by adopting a zero-sequence current characteristic equation according to the change of zero-sequence current of each line before and after the switch-on of the split-phase circuit breaker.
2. The method for fault line selection by using a 66kV active intervention arc suppression device according to claim 1, wherein the method comprises the following steps: the grounding phase selection device comprises a display communication module, an acquisition and calculation module and a driving locking module, wherein the acquisition and calculation module adopts a TMS320F2812DSP signal processor as a CPU (Central processing Unit) for operation, a 14-bit A/D analog-to-digital conversion chip AD7865 performs analog-to-digital conversion to complete signal acquisition of zero sequence voltage and system phase line voltage, the DSP signal processor performs analysis and calculation to judge single-phase grounding faults and identify grounding phases, a corresponding relay is opened to control the action of a single-phase circuit breaker, and calculation data and action waveforms are uploaded to the display communication module through a double-port RAM 7024.
3. The method for fault line selection by using a 66kV active intervention arc suppression device according to claim 1, wherein the method comprises the following steps: the sampling speed of the DSP signal processor is 320-.
4. The method for fault line selection by using a 66kV active intervention arc suppression device according to claim 1, wherein the method comprises the following steps: the driving locking module comprises a metal-oxide-semiconductor field effect transistor (MOSFET), a quick phase selection relay DZK-1, relay contacts J2, J3 and A which are locked with each other, a quick phase selection relay DZK-2, relay contacts J3, J1 and B which are locked with each other, a quick phase selection relay DZK-3, relay contacts J1, J2 and C which are locked with each other, only one phase selection relay is closed at any time, and only one phase selection relay is opened at any time; the nodes of the single-phase circuit breaker are mutually locked, one phase is switched on, and other single-phase circuit breaker switching-on loops are disconnected, so that the condition that two phases are not switched on at any moment is ensured.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2829887A1 (en) * | 2013-07-24 | 2015-01-28 | Schneider Electric Industries SAS | Method and device for estimating angle of zero-sequence voltage in single-phase earth fault |
| CN111551824A (en) * | 2020-05-15 | 2020-08-18 | 中国南方电网有限责任公司 | Phase voltage amplitude and phase angle change rate ground fault phase selection method and device considering three-phase asymmetry |
| CN112526389A (en) * | 2020-11-04 | 2021-03-19 | 国网湖北省电力有限公司电力科学研究院 | Single-phase earth fault line selection device and multidimensional determination method |
-
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2829887A1 (en) * | 2013-07-24 | 2015-01-28 | Schneider Electric Industries SAS | Method and device for estimating angle of zero-sequence voltage in single-phase earth fault |
| CN111551824A (en) * | 2020-05-15 | 2020-08-18 | 中国南方电网有限责任公司 | Phase voltage amplitude and phase angle change rate ground fault phase selection method and device considering three-phase asymmetry |
| CN112526389A (en) * | 2020-11-04 | 2021-03-19 | 国网湖北省电力有限公司电力科学研究院 | Single-phase earth fault line selection device and multidimensional determination method |
Non-Patent Citations (1)
| Title |
|---|
| 唐传佳;魏曼荣;朱汇静;: "中性点不接地系统故障相经低励磁阻抗变压器接地方式的研究", 上海电气技术, no. 01 * |
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