CN107516878A - Intermittent high resistance earthing protecting method and system - Google Patents
Intermittent high resistance earthing protecting method and system Download PDFInfo
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- CN107516878A CN107516878A CN201710730010.4A CN201710730010A CN107516878A CN 107516878 A CN107516878 A CN 107516878A CN 201710730010 A CN201710730010 A CN 201710730010A CN 107516878 A CN107516878 A CN 107516878A
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- 238000004364 calculation method Methods 0.000 claims description 2
- 210000001367 artery Anatomy 0.000 description 6
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
- H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
Abstract
The present invention relates to a kind of intermittent high resistance earthing protecting method and system; according to residual voltage, zero sequence active power and zero sequence reactive power; identify high resistance earthing fault feature; timing is established according to pulse and failure timing broadening judges whether that summation pulse counts; time broadening is put when down pulse is established; having new pulse in time broadening, then step-by-step counting adds up; when step-by-step counting is added to preset times threshold value; trip signal starts, and solves the problems, such as that conventional zero-sequencedirectional protection can not trip or alarm because timing can not reach predetermined threshold value.
Description
Technical field
The present invention relates to a kind of protection of power system and control technology field, is connect more particularly to a kind of intermittent high resistant
Ground guard method and system.
Background technology
When earth fault occurs, Neutral Point Through Low Resistance system can quickly identify and cut off faulty line, because
This is more and more applied in newly-built urban distribution network.
Neutral Point Through Low Resistance system can cut off low resistance grounding failure, 10kV system zero of the neutral point through small resistor
Sequence current protection can only cut off the earth fault below the Europe of transition resistance 100.When high resistance earthing fault occurs, because high resistant connects
Ground is often accompanied by the intermittent situation about extinguishing of electric arc, causes zero-sequence current that pulsed increase and the feature returned is presented, often
Rule protection typically using continue timing mode, when zero-sequence current is more than definite value timing add up, when zero-sequence current is less than definite value
Then timing is reset, and protection returns.In this case, increase because high resistance ground zero-sequence current is intermittent, and the time maintained is very
Short, conventional zero-sequencedirectional protection can not trip or alarm because timing can not reach predetermined threshold value.
The content of the invention
Based on this, it is necessary to can not trip or report because timing can not reach predetermined threshold value for conventional zero-sequencedirectional protection
The problem of alert, there is provided a kind of intermittent high resistance earthing protecting method and system.
A kind of intermittent high resistance earthing protecting method, comprises the following steps：
The threshold value, zero sequence active power absolute value and zero sequence reactive power for obtaining zero sequence active power absolute value are absolute
Value；
Meet that default residual voltage condition, zero sequence active power absolute value condition and zero sequence reactive power are absolute when simultaneously
During value condition, start intermittent high resistance earthing protecting；
After intermittent high resistance earthing protecting is started, starting impulse establishes timer, and establishing timing in pulse reaches the
During one threshold value, an earth fault pulse is established, and down pulse is counted and added up；It is high resistance ground that wherein timing is established in pulse
The pulse duration of failure；
After earth fault pulse is established, failure broadening timer starts countdown, if being fallen in failure broadening timer
Timing establishes new earth fault pulse before terminating, and down pulse is counted cumulative；
When down pulse, which counts, is added to preset times, trip protection isolated fault is performed.
A kind of intermittent high resistance earthing protecting system, including：
Acquisition module, for obtaining threshold value, the zero sequence active power absolute value and zero of zero sequence active power absolute value
Sequence reactive power absolute value；
Presetting module, when simultaneously meet default residual voltage condition, zero sequence active power absolute value condition and zero sequence without
During work(power absolute value condition, start intermittent high resistance earthing protecting；
Module is established in pulse, for after intermittent high resistance earthing protecting is started, starting impulse to establish timer, in arteries and veins
When punching establishes timing and reaches first threshold, an earth fault pulse is established, and down pulse is counted cumulative；Wherein pulse is built
Vertical timing is the pulse duration of high resistance earthing fault；
Failure broadening module, for after earth fault pulse is established, failure broadening timer to start countdown, if
Failure broadening timer countdown establishes new earth fault pulse before terminating, and down pulse is counted cumulative；
Trip module, for when down pulse counts and is added to preset times, performing trip protection isolated fault.
Above-mentioned intermittent high resistance earthing protecting method, according to residual voltage, zero sequence active power and zero sequence reactive power,
High resistance earthing fault feature is identified, timing is established according to pulse and failure timing broadening judges whether that summation pulse counts, works as arteries and veins
When rushing counting and being added to preset times threshold value, trip signal starts, and solves conventional zero-sequencedirectional protection because timing can not reach
Predetermined threshold value and the problem of can not trip or alarm.
Brief description of the drawings
Fig. 1 is the schematic flow sheet of one embodiment of the invention intermittent high resistance earthing protecting method；
Fig. 2 is the neutral point applied in one embodiment of the invention through small resistor system main electrical scheme schematic diagram；
Fig. 3 is the phase of small resistance grounding system high resistance earthing fault when zero sequence CT polarity just connects in one embodiment of the invention
Spirogram；
The phase of small resistance grounding system high resistance earthing fault when Fig. 4 is zero sequence CT error-polarity connections in one embodiment of the invention
Spirogram.
Embodiment
The intermittent high resistance earthing protecting method of the present invention is described in detail with reference to the accompanying drawings and examples.
The present invention provides a kind of intermittent high resistance earthing protecting method, comprises the following steps：
S1：Obtain threshold value, zero sequence active power absolute value and the zero sequence reactive power of zero sequence active power absolute value
Absolute value；
S2：Meet default residual voltage condition, zero sequence active power absolute value condition and zero sequence reactive power when simultaneously
During absolute value condition, start intermittent high resistance earthing protecting；
S3：After intermittent high resistance earthing protecting is started, starting impulse establishes timer, and establishing timing in pulse reaches
During first threshold, an earth fault pulse is established, and down pulse is counted and added up；Wherein pulse is established timing and connect for high resistant
The pulse duration of earth fault；
S4：After earth fault pulse is established, failure broadening timer starts countdown, if in failure broadening timer
Countdown establishes new earth fault pulse before terminating, and down pulse is counted cumulative；
S5：When down pulse, which counts, is added to preset times, trip protection isolated fault is performed.
In above-described embodiment, specific schematic flow sheet is as shown in figure 1, step-by-step counting is more than predetermined threshold value, i.e., more than one
During definite value, outlet tripping operation.For step S1：Zero sequence active power absolute value can be calculated according to residual voltage and zero-sequence current,
In embodiments of the invention, residual voltage refers to open delta residual voltage, and zero-sequence current refers to the zero sequence electricity of each circuit
Stream, zero sequence reactive power absolute value can also be calculated according to the zero sequence active power absolute value；For step S2：Can basis
The value of earth fault transition resistance presets residual voltage condition, and/or active according to zero sequence active power absolute value and zero sequence
The threshold value of power absolute value presets zero sequence active power absolute value condition, and/or according to zero sequence active power absolute value and zero
Relation between sequence reactive power absolute value presets zero sequence reactive power absolute value condition, meets the residual voltage bar when simultaneously
When part, zero sequence active power absolute value condition and zero sequence reactive power absolute value condition, start intermittent high resistance earthing protecting
, can when meeting residual voltage condition, zero sequence active power absolute value condition and zero sequence reactive power absolute value condition simultaneously
To be determined as that the circuit has high resistance earthing fault feature, when at least one condition is unsatisfactory in three conditions, then can sentence
The fixed circuit does not have high resistance earthing fault feature；For step S3：When being determined to have high resistance earthing fault feature, into arteries and veins
Timing is established in punching, when timing is established in pulse reaches the i.e. first threshold of pre-set value of pulse build-up time, it is determined that establish one
Secondary earth fault pulse, down pulse count cumulative；For step S4：Earth fault pulse is determined after establishing in step S3,
Primary fault timing broadening is carried out, that is, it is a specified time to set failure broadening timer, and failure time broadening definite value can be
1s.When not new earth fault pulse is established, failure broadening counter decrements, until being kept to 0；If in failure broadening timing
Device is decremented to before 0 has new earth fault pulse to establish once more, then step-by-step counting continues to add up, simultaneous faults broadening timing
Device recovered to specified time again；If not occurring new earth fault pulse before failure broadening counter decrements to 0,
Down pulse counter is removed, intermittent high resistance earthing protecting returns；For step S5：The threshold of a step-by-step counting can be preset
Value, when step-by-step counting reaches the threshold value, then outlet tripping operation.
The basis for selecting of preparatory condition in step 2 is described in detail with reference to specific example, neutral point is through small electricity
Wiring diagram such as Fig. 2 of earthed system circuit is hindered, can be 10kV earthed systems, containing four circuits：Circuit 1, circuit 2, circuit 3 with
And circuit 4, in figure ground connection change refer to grounding transformer, wherein there occurs through transition resistance eutral grounding failure, A, B and C are circuit 4
The different circuit of three-phase, RrFor neutral resistance, RgFor earth fault transition resistance, neutral resistance RrCan be 6
~20 ohm, and earth fault transition resistance RgCan be in the range of 100~1000 ohm.
If ground connection become zero sequence voltage on neutral point intoIgnore ground connection impedance, then 10kV buses three-phase voltage is because neutral
Point variation, it is respectivelyAccording to Kirchhoff's current law (KCL), formula (1) be present：
Wherein,WithRespectively a, b, c three-phase voltage rated value.In formula (1),For the three-phase of power supply
Electric current sum,For the three-phase current sum of each circuit, RrBecome neutral resistance for ground connection.
When triphase parameter is symmetrical, load is symmetrical, the three-phase current sum of power branch and each non-fault line is computed
After beThat is three-phase ground capacitance electric current isWherein, j is imaginary unit, j2=-1, ω is power frequency pair
The angular speed answered, it is the π × 50 of ω=2 for 50Hz power frequencies, C is the single-phase direct-to-ground capacitance size of circuit, similarly hereinafter.For failure
Circuit, except three-phase ground capacitance electric currentAlso exist due to earth fault transition resistance RgIt is caused to earth-current,
Assuming that earth fault is occurring at for l with bus, the reactance of unit length is x, then so that A phases are grounded as an example, RgIt is caused
It is to earth-current：ByBring the above results into formula (1), be then converted into formula (2)：
According to above-mentioned analysis, for nth bar non-fault line, zero-sequence currentForDirect-to-ground capacitance caused by effect is lower
Electric current：
In formula (3) n be non-fault line sequence number, corresponding diagram 2, n=1,2,3, CnFor nth bar line electricity capacitance.
For faulty line, zero-sequence currentFor three-phase ground capacitance electric currentWith earth fault transition resistance
RgIt is caused to earth-current sum：
∑ C is system direct-to-ground capacitance sum in formula (4), C4For faulty line direct-to-ground capacitance.
According to formula 3 and 4, the zero-sequence current and residual voltage of non-fault line and faulty linePhasor relation as scheme
Shown in 3, wherein, the size of zero-sequence current is 3I0.If zero sequence CT reverse polarity connections, phasor diagram are as shown in Figure 4.
According to Fig. 3 and Fig. 4, active-power P is analyzed0=U0×3I0× Cos θ, θ is between zero-sequence current and residual voltage
Angle, I0 and U0 are respectively the amplitude of zero-sequence current and the amplitude of residual voltage.For non-fault line, no matter zero sequence CT polarity
Positive and negative, active zero sequence is 0, and for faulty line, and zero sequence CT polarity is just connecing, and positive negative equal with absolute value during reversal connection
Instead, the active absolute value of zero sequence is taken, then numerical value is equal.It is active definitely using zero sequence for Neutral Point Through Low Resistance system
It is worth as the foundation for distinguishing faulty line and non-fault line, there is obvious discrimination.Therefore, it is active definitely using zero sequence
Value detects earth fault, can prevent the influence of CT polarity.
According to formula (4), for faulty line, when calculating zero sequence active power, onlySubparticipation calculates, j3 ω
(∑C-C4) active zero sequence caused by part is 0.Therefore, obtaining active power absolute value is：
In formula (2), in the case of high resistance ground, R is consideredgIn the range of 100~1000 ohm, lx is far smaller than Rg, can
Ignore.Consider the situation of overhead line, general overhead line unit direct-to-ground capacitance is 6pF/km or so, and it is about 5.7 μ S/ to convert as admittance
Km, the admittance over the ground when system scale is equivalent to 100km overhead lines are 0.570mS, and it is general to be grounded change neutral resistance
For 6~20 ohm, it is admittance in more than 20mS to convert, much larger than system admittance over the ground, thereforeAlso it can be neglected, obtain
Become the approximate formula of neutral point voltage to following ground connection：
ForAmplitude.Bring into formula (5), obtain the approximate formula of zero sequence active power absolute value：
It is in the majority for cable run, or when power network is on a grand scale, system capacitive earth current is larger, should not directly ignoreWhen, it can obtain：
According to formula (4), it is impossible to when ignoring, j3 ω (∑ C-C4) zero sequence reactance capacity can be formed, it can obtain：
Q0For zero sequence reactive power.For same small resistance grounding system, neutral resistance RrIt is certain, root
According to formula 8 and formula 9, | P0| with grounding resistance RgIncrease and reduce, reduce with the increase of system scale, | Q0| can be with
The increase of system scale and increase.
Above-mentioned analysis is based on transition resistance R during high resistance groundgSignificantly greater than trouble point is to the line reactance lx's of bus
Under the premise of, suitable for 100 Europe and the situation of above transition resistance ground connection.Furthermore, it is contemplated that the factor such as distributed resistance, error
Influence, the zero sequence active power of non-fault line will not be entirely 0, but can show zero sequence reactive power has much larger than zero sequence
The feature of work(power, and faulty line has obvious zero sequence active power, is different in homopolar power distribution.
Using electromagnetic transient simulation software (PSCAD, Power Systems Computer Aided Design) to Fig. 2
In system carry out electromagnetic transient simulation, voltage class 10.5kV, neutral resistance is 10 Europe.Transition resistance is 100
Europe~1000 selects in the range of Europe, calculates residual voltage at 10kV buses and flows through the zero-sequence current of each bar distribution line, and counts
Calculate the zero sequence active power absolute value of each bar circuit.
Each circuit during different transition resistances | P0|、|Q0| as shown in Table 1 and Table 2, using two sub-values, unit W, Var：
Each circuit during 1 different transition resistances of table
| Rg(Ω) | Circuit 1 | Circuit 2 | Circuit 3 | Circuit 4 |
| 100 | 1.33e-3 | 4.21e-4 | 2.24e-3 | 4.81 |
| 200 | 3.74e-4 | 1.18e-4 | 6.27e-4 | 1.35 |
| 400 | 9.91e-5 | 3.13e-5 | 1.66e-4 | 0.358 |
| 600 | 4.49e-5 | 1.42e-5 | 7.54e-5 | 0.162 |
| 800 | 2.55e-5 | 8.05e-6 | 4.28e-5 | 0.0921 |
| 1000 | 1.64e-5 | 5.18e-6 | 2.76e-5 | 0.0592 |
Each circuit during 2 different transition resistances of table
| Rg(Ω) | Circuit 1 | Circuit 2 | Circuit 3 | Circuit 4 |
| 100 | 0.218 | 0.148 | 0.261 | 0.904 |
| 200 | 0.0610 | 0.0406 | 0.0732 | 0.253 |
| 400 | 0.0162 | 0.0108 | 0.0194 | 0.0672 |
| 600 | 7.33e-3 | 4.88e-3 | 8.81e-3 | 0.0305 |
| 800 | 4.16e-3 | 2.77e-3 | 5.00e-3 | 0.0173 |
| 1000 | 2.68e-3 | 1.78e-3 | 3.22e-3 | 0.0111 |
In table 1, the zero sequence active power absolute value of circuit 4 and the result of calculation of formula (7) are identical.Expansion system is advised
Mould, increase the total amount of system direct-to-ground capacitance, simulation result during different transition resistances is as shown in the table：
Each circuit during 3 different transition resistances of table
| Rg(Ω) | Circuit 1 | Circuit 2 | Circuit 3 | Circuit 4 |
| 100 | 0.0248 | 0.0115 | 0.0608 | 3.31 |
| 200 | 7.11e-3 | 3.29e-3 | 0.0175 | 0.951 |
| 400 | 1.91e-3 | 8.84e-4 | 4.69e-3 | 0.255 |
| 600 | 8.70e-4 | 4.03e-4 | 2.13e-3 | 0.116 |
| 800 | 4.95e-4 | 2.29e-4 | 1.22e-3 | 0.0662 |
| 1000 | 3.19e-4 | 1.48e-4 | 7.83e-4 | 0.0427 |
Each circuit during 4 different transition resistances of table
It is consistent that above-mentioned simulation result derives with theoretical formula.In the above-described embodiments, because high resistance earthing fault is deposited
It is higher to required precision failure amount is small the characteristics of, special zero sequence CT can be used as far as possible, but special zero sequence CT polarity is difficult to
Verification.Above-described embodiment zero-sequence current is accessed using special zero sequence CT, and is capable of adaptive zero sequence CT polarity, ensure that height
Resistance earth fault judges requirement to precision, and with the feelings of intermittent defect feature when can adapt to high resistance earthing fault
Condition.
The basis for selecting of preparatory condition in step 2 is discussed in detail above-mentioned example, and concrete application is based on above-mentioned default
Condition, it is capable of the situation of adaptive special zero sequence CT error-polarity connections, it is not necessary to special zero sequence CT polarity is verified, and can be fine
Exclusion capacitive earth current influence, high sensitivity, using special zero sequence CT and open delta voltage, can adapt to high resistant
The small needs of fault characteristic value accurate the characteristics of measuring during ground connection.
Wherein, one embodiment of the present of invention intermittent high resistance earthing protecting method, timer is established in starting impulse
Afterwards, it is further comprising the steps of：If established in pulse before timing reaches first threshold, the residual voltage condition, zero sequence
At least one condition is unsatisfactory in active power absolute value condition and zero sequence reactive power absolute value condition, then is built pulse
Vertical timer is reset.
Wherein described first threshold can be 100ms, only meet default residual voltage condition, default zero sequence simultaneously
When active power absolute value condition and default zero sequence reactive power absolute value condition, it is possible to determine that there is high resistant for the circuit
Earth fault feature, as long as there is one to be unsatisfactory in these three conditions, then it is determined as that high resistance earthing fault feature disappears.
High resistance earthing fault feature can be judged exactly by above-described embodiment, high resistance ground event occurs in distribution line
It during barrier, can in time be removed, not only be avoided that and endangered because distribution line drops step voltage caused by ground or contact voltage
Passer-by, moreover it is possible to ensure that upper level grounding transformer is unlikely to be influenceed by failure, improve the reliability of power supply.
Preferably, the intermittent high resistance earthing protecting method of one embodiment of the invention, start in failure broadening timer
It is further comprising the steps of after countdown：Without the earth fault arteries and veins that appearance is new before failure broadening counter decrements to 0
Punching, then by down pulse counter O reset.
In the above-described embodiments, when not new earth fault pulse is established, failure broadening counter decrements, until subtracting
For 0；If not occurring new earth fault pulse before failure broadening counter decrements to 0, remove down pulse and count
Device, intermittent high resistance earthing protecting return.
Above-described embodiment, counted by the down pulse in default failure broadening timing to identify intermittent high resistance ground
Fault signature, avoids judging by accident, be not only avoided that pass by one's way pedestrian because distribution line drop step voltage caused by ground or contact electricity
Press and endanger passer-by, moreover it is possible to ensure that upper level grounding transformer is unlikely to be influenceed by failure, improve power supply
Reliability.
Specifically, the intermittent high resistance earthing protecting method of the present invention, is obtaining the threshold of zero sequence active power absolute value
It is further comprising the steps of before value：
Zero sequence active power is calculated according to the neutral resistance of small resistance grounding system and earth fault transition resistance
The threshold value of absolute value.
In above-described embodiment, neutral resistance Rr can be 6~20 ohm, and earth fault transition resistance Rg can be with
It is absolute for default zero sequence active power by calculating the threshold value of zero sequence active power absolute value in the range of 100~1000 ohm
Value condition is laid the groundwork, and can be made whether high resistance earthing fault spy be present by default zero sequence active power absolute value condition
Sign.Identification high resistance earthing fault feature is most important to starting high resistance earthing protecting in time in time.
In a specific embodiment, in intermittent high resistance earthing protecting method, the calculating zero sequence active power
The formula of the threshold value of absolute value is：
In formula, | P0|ThresholdFor the threshold value of zero sequence active power absolute value, EaFor phase voltage rated value, KrIt is reliable for first
Coefficient, RrFor neutral resistance, RgFor earth fault transition resistance.
In above-described embodiment, EaProtection can use two sub-values to calculate, and take 57.74V；It is to consider access open delta
The secondary rated value of voltage is 100V, is had with phase voltageTimes relation；To ensure the sensitivity of high resistance earthing protecting, KrCan
0.5~0.8 is taken, representative value can take 0.6.
Above-described embodiment can obtain the threshold value of zero sequence active power absolute value, zero sequence active power in distribution line
The threshold value that value is more than above-mentioned zero sequence active power absolute value is one of decision condition that high resistance earthing fault occurs for distribution line,
It can judge whether to occur by the comparison to zero sequence active power absolute value and the threshold value of zero sequence active power absolute value
High resistance earthing fault.
Preferably, in the embodiment of intermittent high resistance earthing protecting method of the invention, first safety factor passes through
Following formula is calculated：
In formula, KkFor nargin coefficient, the ω C of Σ 3 are susceptance value corresponding to total system direct-to-ground capacitance, and ω is angle corresponding to power frequency
Speed.
In above-described embodiment, KkRepresentative value 0.85 can be taken, it is electric corresponding to total system direct-to-ground capacitance when power frequency is 50Hz
Value of receiving is π × 50 of ω=2.The threshold value for being calculated as zero sequence active power absolute value of safety factor is laid the groundwork, can be by right
The comparison of the threshold value of zero sequence active power absolute value and zero sequence active power absolute value is former to judge whether generation high resistance ground
Barrier.
Specifically, the intermittent high resistance earthing protecting method in one embodiment of the present of invention, the residual voltage condition,
Zero sequence active power absolute value condition and zero sequence reactive power absolute value condition are：
In formula, U0For residual voltage, | P0| it is zero sequence active power absolute value, | Q0| it is zero sequence reactive power absolute value, Kpq
It is relevant with the direct-to-ground capacitance total amount of system for the first coefficient, KuFor the second safety factor.
In above-described embodiment, KpqFor the coefficient relevant with the direct-to-ground capacitance total amount of system, 0.3, K can be takenuFor zero sequence electricity
Safety factor corresponding to pressure, Ea、Kr、Rr、RgMeaning it is identical with other embodiment, here is omitted.
Above-described embodiment is capable of the situation of adaptive special zero sequence CT error-polarity connections, it is not necessary to verifies special zero sequence CT pole
Property, and can be good at excluding the influence of capacitive earth current, high sensitivity, using special zero sequence CT and open delta electricity
Pressure, it can adapt to the characteristics of small needs of fault characteristic value during high resistance ground accurately measure.
Specifically, the intermittent high resistance earthing protecting in embodiments of the invention can also set pulse to establish the of timing
One threshold value, the Second Threshold of failure timing broadening, the 3rd threshold value of step-by-step counting；Within the time of the Second Threshold, work as arteries and veins
When punching establishes timing and reaches the first threshold, step-by-step counting adds up, when step-by-step counting is added to three threshold value, tripping operation
Order starts.Timer timing since 0 is established in the pulse, until clocking value reaches first threshold；Failure broadening timer
The countdown since Second Threshold, until clocking value is 0；Pulse counter timing since 0, reach the 3rd threshold until counting
Value.Refer to the failure broadening timer this period of countdown up to 0 since Second Threshold in the time of the Second Threshold
It is interior.High resistance earthing protecting provides above-mentioned pulse and establishes the first threshold of timing, the Second Threshold of failure timing broadening and pulse
The 3rd threshold value counted is set for user, and user can preset these three values according to different situation and demand, these three values
Predeterminable property for the present invention intermittent high resistance earthing protecting method provides widely use, by set these three values come
Match different distribution lines.
In addition, the having a rest property high resistance earthing protecting system of one embodiment of the present of invention, including：
Acquisition module, for obtaining threshold value, the zero sequence active power absolute value and zero of zero sequence active power absolute value
Sequence reactive power absolute value；
Presetting module, it is active according to zero sequence for presetting residual voltage condition according to the value of earth fault transition resistance
The threshold value of power absolute value and zero sequence active power absolute value presets zero sequence active power absolute value condition, active according to zero sequence
Relation between power absolute value and zero sequence reactive power absolute value presets zero sequence reactive power absolute value condition, meets when simultaneously
When the residual voltage condition, zero sequence active power absolute value condition and zero sequence reactive power absolute value condition, start interval
Property high resistance earthing protecting；
Module is established in pulse, for after intermittent high resistance earthing protecting is started, starting impulse to establish timer, in arteries and veins
When punching establishes timing and reaches first threshold, an earth fault pulse is established, and down pulse is counted cumulative；Wherein pulse is built
Vertical timing is the pulse duration of high resistance earthing fault；
Failure broadening module, for after earth fault pulse is established, failure broadening timer to start countdown, if
Failure broadening timer countdown establishes new earth fault pulse before terminating, and down pulse is counted cumulative；
Trip module, for when down pulse counts and is added to preset times, performing trip protection isolated fault.
Above-mentioned is that embodiment and corresponding embodiment in the intermittent high resistance earthing protecting method of the present invention are similar, herein
Repeat no more.
Embodiment described above only expresses the several embodiments of the present invention, and its description is more specific and detailed, but simultaneously
Can not therefore it be construed as limiting the scope of the patent.It should be pointed out that come for one of ordinary skill in the art
Say, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the protection of the present invention
Scope.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.
Claims (9)
1. a kind of intermittent high resistance earthing protecting method, it is characterised in that comprise the following steps：
Obtain threshold value, zero sequence active power absolute value and the zero sequence reactive power absolute value of zero sequence active power absolute value；
Meet default residual voltage condition, zero sequence active power absolute value condition and zero sequence reactive power absolute value bar when simultaneously
During part, start intermittent high resistance earthing protecting；
After intermittent high resistance earthing protecting is started, starting impulse establishes timer, and establishing timing in pulse reaches the first threshold
During value, an earth fault pulse is established, and down pulse is counted and added up；It is high resistance earthing fault that wherein timing is established in pulse
Pulse duration；
After earth fault pulse is established, failure broadening timer starts countdown, if in failure broadening timer countdown
New earth fault pulse is established before terminating, down pulse is counted cumulative；
When down pulse, which counts, is added to preset times, trip protection isolated fault is performed.
2. intermittent high resistance earthing protecting method according to claim 1, it is characterised in that connect starting intermittent high resistant
It is further comprising the steps of before ground protection：
Residual voltage condition is preset according to the value of earth fault transition resistance；And/or
Zero sequence active power absolute value is preset according to the threshold value of zero sequence active power absolute value and zero sequence active power absolute value
Condition；And/or
It is absolute that zero sequence reactive power is preset according to the relation between zero sequence active power absolute value and zero sequence reactive power absolute value
Value condition.
3. intermittent high resistance earthing protecting method according to claim 1, it is characterised in that establish timing in starting impulse
It is further comprising the steps of after device：
If established in pulse before timing reaches first threshold, the residual voltage condition, zero sequence active power absolute value bar
At least one condition is unsatisfactory in part and zero sequence reactive power absolute value condition, then pulse is established into timer resets.
4. intermittent high resistance earthing protecting method according to claim 1, it is characterised in that opened in failure broadening timer
It is further comprising the steps of after beginning countdown：
If not occurring new earth fault pulse before failure broadening counter decrements to 0, down pulse is counted
Device is reset.
5. small resistance grounding system high resistance earthing protecting method according to claim 1, it is characterised in that obtaining zero sequence
It is further comprising the steps of before the threshold value of active power absolute value：
It is absolute that zero sequence active power is calculated according to the neutral resistance of small resistance grounding system and earth fault transition resistance
The threshold value of value.
6. intermittent high resistance earthing protecting method according to claim 5, it is characterised in that the zero sequence active power is exhausted
Calculation formula to the threshold value of value is：
In formula, | P0|ThresholdFor zero sequence active power threshold value, EaFor phase voltage rated value, KrFor the first safety factor, RrFor neutrality
Point grounding resistance, RgFor earth fault transition resistance.
7. intermittent high resistance earthing protecting method according to claim 6, it is characterised in that first safety factor leads to
Following formula is crossed to be calculated：
<mrow>
<msub>
<mi>K</mi>
<mi>r</mi>
</msub>
<mo><</mo>
<msub>
<mi>K</mi>
<mi>k</mi>
</msub>
<mo>&times;</mo>
<mfrac>
<msup>
<mrow>
<mo>(</mo>
<msub>
<mi>R</mi>
<mi>r</mi>
</msub>
<mo>+</mo>
<msub>
<mi>R</mi>
<mi>g</mi>
</msub>
<mo>)</mo>
</mrow>
<mn>2</mn>
</msup>
<mrow>
<msup>
<mrow>
<mo>(</mo>
<msub>
<mi>R</mi>
<mi>r</mi>
</msub>
<mo>+</mo>
<msub>
<mi>R</mi>
<mi>g</mi>
</msub>
<mo>)</mo>
</mrow>
<mn>2</mn>
</msup>
<mo>+</mo>
<msup>
<mrow>
<mo>(</mo>
<mi>&Sigma;</mi>
<mn>3</mn>
<msub>
<mi>&omega;CR</mi>
<mi>r</mi>
</msub>
<msub>
<mi>R</mi>
<mi>g</mi>
</msub>
<mo>)</mo>
</mrow>
<mn>2</mn>
</msup>
</mrow>
</mfrac>
</mrow>
In formula, KrFor the first safety factor, KkFor nargin coefficient, the ω C of ∑ 3 are that susceptance value, ω corresponding to total system direct-to-ground capacitance are
Angular speed corresponding to power frequency.
8. intermittent high resistance earthing protecting method according to claim 6, it is characterised in that the default residual voltage
Condition, default zero sequence active power absolute value condition and default zero sequence reactive power absolute value condition are：
<mfenced open = "{" close = "">
<mtable>
<mtr>
<mtd>
<mrow>
<msub>
<mi>U</mi>
<mn>0</mn>
</msub>
<mo><</mo>
<msub>
<mi>K</mi>
<mi>u</mi>
</msub>
<mo>&times;</mo>
<mfrac>
<mrow>
<mn>100</mn>
<mi>V</mi>
<mo>&times;</mo>
<msub>
<mi>R</mi>
<mi>r</mi>
</msub>
</mrow>
<mrow>
<msub>
<mi>R</mi>
<mi>r</mi>
</msub>
<mo>+</mo>
<mn>100</mn>
<mi>&Omega;</mi>
</mrow>
</mfrac>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<mo>|</mo>
<msub>
<mi>P</mi>
<mn>0</mn>
</msub>
<mo>|</mo>
<mo>></mo>
<msqrt>
<mn>3</mn>
</msqrt>
<mo>&times;</mo>
<msub>
<mi>K</mi>
<mi>r</mi>
</msub>
<mo>&times;</mo>
<mfrac>
<mrow>
<msubsup>
<mi>E</mi>
<mi>a</mi>
<mn>2</mn>
</msubsup>
<mo>&times;</mo>
<msub>
<mi>R</mi>
<mi>r</mi>
</msub>
</mrow>
<msup>
<mrow>
<mo>(</mo>
<msub>
<mi>R</mi>
<mi>r</mi>
</msub>
<mo>+</mo>
<msub>
<mi>R</mi>
<mi>g</mi>
</msub>
<mo>)</mo>
</mrow>
<mn>2</mn>
</msup>
</mfrac>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<mo>|</mo>
<msub>
<mi>P</mi>
<mn>0</mn>
</msub>
<mo>|</mo>
<mo>></mo>
<msub>
<mi>K</mi>
<mrow>
<mi>p</mi>
<mi>q</mi>
</mrow>
</msub>
<mo>&times;</mo>
<mo>|</mo>
<msub>
<mi>Q</mi>
<mn>0</mn>
</msub>
<mo>|</mo>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
In formula, U0For residual voltage, | P0| it is zero sequence active power absolute value, | Q0| it is zero sequence reactive power absolute value, KpqFor
One coefficient, K relevant with the direct-to-ground capacitance total amount of systemuFor the second safety factor.
A kind of 9. intermittent high resistance earthing protecting system, it is characterised in that including：
Acquisition module, for obtain the threshold value, zero sequence active power absolute value and zero sequence of zero sequence active power absolute value without
Work(power absolute value；
Presetting module, for ought meet simultaneously default residual voltage condition, zero sequence active power absolute value condition and zero sequence without
During work(power absolute value condition, start intermittent high resistance earthing protecting；
Module is established in pulse, for after intermittent high resistance earthing protecting is started, starting impulse to establish timer, is built in pulse
When vertical timing reaches first threshold, an earth fault pulse is established, and down pulse is counted and added up；Wherein meter is established in pulse
When for high resistance earthing fault pulse duration；
Failure broadening module, for after earth fault pulse is established, failure broadening timer to start countdown, if in failure
Broadening timer countdown establishes new earth fault pulse before terminating, and down pulse is counted cumulative；
Trip module, for when down pulse counts and is added to preset times, performing trip protection isolated fault.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109728568A (en) * | 2018-12-17 | 2019-05-07 | 广州供电局有限公司 | The starting method and apparatus of small resistance grounding system high resistance earthing protecting |
| CN110601157A (en) * | 2019-09-30 | 2019-12-20 | 南京国电南自电网自动化有限公司 | Intermittent single-phase earth fault protection method and device |
| CN111474494A (en) * | 2020-03-20 | 2020-07-31 | 南京南瑞继保工程技术有限公司 | High-resistance grounding fault detection method and device of small-resistance grounding system |
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|---|---|---|---|---|
| CN103529344A (en) * | 2013-08-15 | 2014-01-22 | 国家电网公司 | Method for detecting intermittent high-resistance grounding fault through intermittent detection |
| CN103529358A (en) * | 2013-08-15 | 2014-01-22 | 国家电网公司 | Method for detecting continuous high-impedance-grounded fault of medium-voltage distribution system by current information |
| CN103529316A (en) * | 2013-08-15 | 2014-01-22 | 国家电网公司 | Comprehensive detection method for high resistance ground faults of electric power system |
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2017
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103529344A (en) * | 2013-08-15 | 2014-01-22 | 国家电网公司 | Method for detecting intermittent high-resistance grounding fault through intermittent detection |
| CN103529358A (en) * | 2013-08-15 | 2014-01-22 | 国家电网公司 | Method for detecting continuous high-impedance-grounded fault of medium-voltage distribution system by current information |
| CN103529316A (en) * | 2013-08-15 | 2014-01-22 | 国家电网公司 | Comprehensive detection method for high resistance ground faults of electric power system |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109728568A (en) * | 2018-12-17 | 2019-05-07 | 广州供电局有限公司 | The starting method and apparatus of small resistance grounding system high resistance earthing protecting |
| CN110601157A (en) * | 2019-09-30 | 2019-12-20 | 南京国电南自电网自动化有限公司 | Intermittent single-phase earth fault protection method and device |
| CN111474494A (en) * | 2020-03-20 | 2020-07-31 | 南京南瑞继保工程技术有限公司 | High-resistance grounding fault detection method and device of small-resistance grounding system |
| CN111474494B (en) * | 2020-03-20 | 2022-08-26 | 南京南瑞继保工程技术有限公司 | High-resistance grounding fault detection method and device of small-resistance grounding system |
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