Summary of the invention
Object of the present invention is exactly to solve the problem, propose a kind of large scale electric network intelligent failure diagnosis method based on differential principle, the method can accurate quick position abort situation, and automatically diagnostic result is pushed on main wiring diagram, have applied widely, accuracy of judgement, diagnostic result push automatically, not by advantages such as the factor such as system operation mode and system oscillation affect, propose the method for a kind of transmission line malfunction diagnosis, and for double bus scheme, specific description has been done to transmission line malfunction diagnostic method.
To achieve these goals, the present invention adopts following technical scheme:
Based on a large scale electric network intelligent failure diagnosis method for differential principle, comprise the following steps:
Step 1: sample with setting-up time interval automatic-calling failure wave-recording;
Step 2: when electrical network normally runs is that unit carries out the calculating of phase current differential value with power transmission and transforming equipment; If differential current computing value starts definite value lower than difference current, then return step 1; If the difference current that differential current computing value is greater than corresponding device starts definite value, then go to step 3;
Step 3: by long-range adjustment fault oscillograph parameter, or site inspection fault oscillograph whether all access participate in the equipment of differential current computing and whether current return exists multipoint earthing problem and carry out defect elimination in time, until differential current computing value starts definite value lower than difference current;
Step 4: during grid collapses, according to fault oscillograph transmit fault data, respectively with electrical network autonomous device for computing unit, carry out the differential current computing of grid equipment phase current; Described electrical network autonomous device comprises: bus equipment, transformer equipment and transmission line of electricity;
For transmission line malfunction, first fault primary election is carried out to transmission line of electricity, filter out suspected malfunctions circuit, then calculate the poor flow valuve of suspected malfunctions circuit;
Step 5: difference flow valuve and difference flows setting valve and compare, if difference flow valuve is out-of-limit, then judges to break down, while fault location determine protection act; If difference flow valuve is not out-of-limit, then judge non-fault or external area error; All automatically, fault diagnosis report is pushed in two kinds of situations.
In described step 4, the method that transmission line of electricity carries out fault primary election comprises: branch current phase-comparison method and comprehensive directional element identification method;
Described branch current phase-comparison method is:
First determine whether doubtful bus-bar fault, if not doubtful bus-bar fault, then judge the phase place of each branch current, by phase compare, judge suspected malfunctions branch road;
Described comprehensive directional element identification method is:
For asymmetry fault, according to different fault types, by judging zero-sequence direction component and negative-sequence direction component direction, judge whether circuit is suspected malfunctions circuit;
For symmetrical fault, impedance directional element is adopted to carry out suspected malfunctions line identifying.
In described step 4, the method that transmission line of electricity carries out fault primary election is branch current phase-comparison method:
For circuit branch road quantity >=3, the situation of two bus paired runnings:
(1) if bus difference flow valuve is greater than A, and difference flow valuve/braking current value is greater than B, be then bus-bar fault; Wherein, A and B is action setting valve, is setting value;
(2) if do not meet (1), be then circuit branch trouble or main transformer branch trouble, suspected malfunctions branch road judges as follows:
The first step: choose the maximum branch road of fault current as benchmark branch road, with its fault current for benchmark branch current;
Second step: other have the fault current of stream branch road to carry out phase compare with benchmark branch current respectively:
If all branch currents and benchmark branch current phase differential all meet 120 degree ~ 240 degree, then benchmark branch road is suspected malfunctions branch road;
If only have 1 branch road and benchmark branch road phase differential to meet 120 degree ~ 240 degree, remain all branch roads and benchmark branch road phase differential and all satisfied-60 spend about ~ 60 degree; The branch road then meeting 120 degree ~ 240 degree with benchmark branch road phase differential is suspected malfunctions branch road.
In described step 4, the method that transmission line of electricity carries out fault primary election is branch current phase-comparison method:
For circuit branch road quantity=2, the situation of two bus paired runnings:
(1) if bus difference flow valuve is greater than A, and difference flow valuve/braking current value is greater than B, be then bus-bar fault; Wherein, A and B is action setting valve, is setting value;
(2) if do not meet (1), be then circuit branch trouble or main transformer branch trouble, suspected malfunctions branch road judges as follows:
Measurement impedance is positive circuit is suspected malfunctions branch road, and measurement impedance is negative circuit is non-fault line.
In described step 4, the method that transmission line of electricity carries out fault primary election is branch current phase-comparison method:
For circuit branch road quantity=1, the situation of two bus paired runnings:
(1) if bus difference flow valuve is greater than A, and difference flow valuve/braking current value is greater than B, be then bus-bar fault; Wherein, A and B is action setting valve, is setting value;
(2) if do not meet (1), be then circuit branch trouble or main transformer branch trouble, if certain circuit branch current secondary current is less than C, C is setting value, then this circuit branch road is suspected malfunctions branch road.
In described step 4, the method that transmission line of electricity carries out fault primary election is comprehensive directional element identification method:
For asymmetry fault, concrete determination methods is:
(1) single-phase fault: zero-sequence direction component, negative-sequence direction component are positive dirction;
(2) double earthfault: zero-sequence direction component, negative-sequence direction component are positive dirction;
(3) line to line fault phase to phase fault: without zero sequence, negative-sequence direction component is positive dirction;
If certain circuit both sides directional element is all shown as positive dirction, then this circuit is suspected malfunctions circuit.
Described zero-sequence direction component is that positive dirction meets:
Described zero-sequence direction component is that positive dirction meets:
Described negative-sequence direction component is that positive dirction meets:
Wherein,
for zero-sequence current,
for residual voltage,
for negative-sequence current,
for negative sequence voltage.
In described step 4, the method that transmission line of electricity carries out fault primary election is comprehensive directional element identification method:
For symmetrical fault, concrete determination methods is:
During network system generation symmetrical fault, transmission line of electricity is without zero sequence and negative sequence component, phase to phase impedance directional element is adopted to carry out faulty line identification, interphase distance relay is for judging the direction of phase to phase impedance directional element, if the polarizing voltage of interphase distance relay, operating voltage meet operating criterion equation below, then prove that phase to phase impedance directional element is positive dirction; Described criterial equation is:
Wherein,
for polarizing voltage,
For operating voltage,
for fault voltage between phases,
for fault three-phase current, Z
setline taking road positive sequence impedance definite value Z can be fixed
l11.2 ~ 1.5 times;
If the phase to phase impedance directional element of certain circuit both sides all meets above-mentioned corresponding actions criterion, then this circuit is suspected malfunctions circuit.
The invention has the beneficial effects as follows:
The present invention utilizes the accurate quick position abort situation of differential principle, and automatically diagnostic result is pushed on main wiring diagram, have applied widely, accuracy of judgement, diagnostic result pushes automatically, not by advantages such as the factor such as system operation mode and system oscillation affect, by each interval fault current, abort situation and diagnostic result push automatically, unified displaying directly perceived on main wiring diagram, for accident treatment provides the decision support of urgent need, fundamentally change fault Artificial Diagnosis traditional mode, for accident treatment provides the decision support of urgent need, effective lifting large scale electric network controling power.
The discrimination method for line fault that the present invention proposes, principle is simple, accuracy of judgement, and not by network frame topology structure influence, without the need to voltage, accurate locating bad lines, does not affect by load, vibration, power inverted orientation etc.First judge doubtful line fault, then utilize the further identification of defective circuit of differential principle, judged result accurately and reliably, significantly reduces workload.
Embodiment:
Below in conjunction with accompanying drawing and embodiment, the present invention will be further described:
Fig. 1 is the differential current computing block plan fault diagnosis principle figure of wide area Fault Recorder Information; as seen from the figure its differential current computing Region dividing respectively and each interval differential main protection scope kissing and, utilize differential principle accuracy of judgement, by the accurate fault location of peculiar advantage such as system operation mode, transition resistance, load current, power inverted orientation, system diagnostics with evaluate protection act behavior.
When electrical network normally runs, sample with Fixed Time Interval automatic-calling failure wave-recording and carry out with power transmission and transforming equipment be unit phase current differential value calculate, difference flow valuve should be almost nil.If differential current computing value is greater than the out-of-limit value of difference stream of corresponding device, (the out-of-limit value of difference stream of each equipment is adjusted as should be load unbalanced during electrical network maximum operational mode, the factors such as CT error cause the maximum difference stream value that may occur), by scheduling station long-range adjustment fault oscillograph access septal pathways title, CT polarity and no-load voltage ratio coefficient, or site inspection fault oscillograph whether all access participate in the equipment of differential current computing and whether current return exists multipoint earthing problem and carry out defect elimination in time, when ensureing that electrical network normally runs, the differential current computing value of all power transmission and transforming equipments is all close to zero.
During grid collapses, according to the fault data that fault oscillograph send, respectively with electrical network autonomous device for computing unit, carry out the differential current computing of electrical network primary current; Difference flow valuve is flowed setting valve with difference compare, realize location, exact failure position and protection act behavior evaluation.Its idiographic flow is illustrated in fig. 2 shown below:
This method for diagnosing faults only needs data of fault recorder; during fault diagnosis; data of fault recorder etc. are all the part of data acquisition of bus protection, tranformer protection, line protective devices; therefore access the branch road of fault oscillograph, CT Secondary Winding type and polarity and should meet following requirement; as space is limited, for the 220kV transformer substation bus equipment fault identification method of double bus scheme form:
(1) transformer station of main transformer fault oscillograph is configured separately, this station all main transformer 220kV high voltage side current analog quantity should be connected in series to our station line fault oscillograph, ensures that all branch roads of normal station median generatrix access same fault oscillograph to realize sample-synchronous.In intelligent station, all fault oscillographs are entirely stood and are adopted unified synchronous clock, and all branch roads of bus are without the need to being connected to same fault oscillograph.
(2) the CT winding accessing fault oscillograph should select line side CT winding (protected level).
(3) access the circuit of fault oscillograph, CT Same Name of Ends of transformer branch should in bus bar side, mother CT Same Name of Ends should in I bus bar side, and corresponding CT Secondary Winding should be Same Name of Ends outlet.If CT Same Name of Ends of access fault oscillograph is towards contrary to the above, corresponding CT Secondary Winding should change non-same polarity outlet into and arrange requirement to meet polarity.
1. bus equipment
The large difference of bus, little poor computing formula are as follows:
1. large spill current: I
cd=I
1+ I
2+ ... + I
n
2. I female little spill current: I
cd1=I
1× S
11+ I
2× S
12+ ... + I
n× S
1n+ I
mL× S
mL
II female little spill current: I
cd2=I
1× S
21+ I
2× S
22+ ... + I
n× S
2n-I
mL× S
mL
In formula, I
1, I
2..., I
nrepresent each branch current vector; I
mLrepresent mother current digital amount; S
11, S
12..., S
1nrepresent the female disconnecting link position of each branch road I (0 represents that disconnecting link divides, and 1 represents that disconnecting link closes); S
21, S
22..., S
2nrepresent the female disconnecting link position of each branch road II; S
mLrepresent bus paired running state (0 represents split operation, and 1 represents paired running).
Large poor loop is the differential circuit that on the bus except bus connection switch, all the other branch currents all are formed; Certain section of little poor loop of bus is the differential circuit that each branch current be connected with this bus is formed, and which includes the bus connection switch be associated with this section of bus.
2. transformer equipment
Transformer differential current:
be respectively the current phasor after transformer each side adjustment.With reference to lower Fig. 3, for Y/Y/ Δ-11, the computing formula of difference current is as follows:
A differs stream:
B differs stream:
C differs stream:
In formula above,
be respectively high, medium and low voltage side a, b, c phase current phasor two sub-value; k
h, k
m, k
lbe respectively the CT no-load voltage ratio of high-pressure side, medium voltage side, low-pressure side; V
h, V
m, V
lbe respectively the rated voltage of high-pressure side, medium voltage side, low-pressure side.
All fault recorder datas of the station equipment such as bus, transformer, all in same seat transformer station, therefore can utilize differential principle to carry out fault accurate recognition easily.
3. transmission line of electricity
Transmission line of electricity is different from bus, transformer equipment, its fault data is stored in two different substation internal fault oscillographs, if directly adopt Line Differential principle to carry out faulty line identification, advantage is that principle is simple, accuracy of judgement, not by network frame topology structure influence, without the need to voltage, accurate locating bad lines, does not affect by load, vibration, power inverted orientation etc.But because needs circuit offside Fault Recorder Information, at present whole network data unified clock are difficult to realize, therefore need manually to carry out the operation such as both sides data-mapping, fault data sample-synchronous, therefore native system preferentially adopts following two kinds of methods to carry out faulty line primary election to alleviate workload, checks suspected malfunctions circuit recycling differential principle, confirms.
3.1 each branch current phase-comparison methods
The advantage of the method is without the need to circuit offside Fault Recorder Information, without the need to voltage, and computing velocity is fast, only needs the magnitude of current to carry out identification.
(1) transformer station's (circuit branch road quantity >=3, mother co-bit) of " access main transformer branch road ":
1) bus difference flow valuve is greater than 400A, and difference flow valuve/braking current value is greater than 0.4, be then bus-bar fault;
2) if do not meet 1), then one is decided to be circuit/main transformer interval fault, judges as follows:
The first step: the branch road choosing fault current maximum (or larger), with its fault current for reference vector.
Second step: other have stream branch road (secondary current is greater than 0.4A) fault current to carry out phase compare with benchmark branch current respectively.
3rd step, all branch currents and benchmark branch current phase differential are about 180 degree, then for benchmark branch road is fault branch; If only have 1 branch road and benchmark branch road phase differential to be about 180 degree (120 degree ~ 240 degree), other all branch roads and benchmark branch road phase differential are 0 degree (-60 spend ~ 60 degree) left and right; The branch road being then about 180 degree with benchmark branch road phase differential is fault branch.(generally should be the branch road that fault current is maximum)
(2) transformer station's (circuit branch road quantity=2, mother co-bit) of " access main transformer branch road ":
1) bus difference flow valuve is greater than 400A, and difference flow valuve/braking current value is greater than 0.4, be then bus-bar fault;
2) if do not meet 1), then one is decided to be circuit/main transformer interval fault, and sampling impedance directional element differentiates, judges as follows:
Measurement impedance (comprising three impedance ground elements and three phase to phase impedance elements) for positive circuit be fault branch, measurement impedance is negative circuit is non-fault line.
(3) transformer station's (circuit branch road quantity=1, mother co-bit) of " access main transformer branch road ":
1) bus difference flow valuve is greater than 400A, and difference flow valuve/braking current value is greater than 0.4, be then bus-bar fault;
2) if do not meet 1), then one is decided to be circuit/main transformer interval fault, and circuit branch current secondary current is less than 0.4A, then fault branch is this circuit branch road.
3.2 comprehensive directional element identification methods
The advantage of the method is not by network frame topology structure influence, without the need to offside Fault Recorder Information, only needs this side electric current and voltage amount to carry out identification.
(1) asymmetry fault
1) single-phase fault: zero sequence direction, negative-sequence direction component should be positive dirction
2) double earthfault: zero sequence direction, negative-sequence direction component should be positive dirction
3) line to line fault phase to phase fault, without zero sequence, negative sequence direction should be positive dirction
Empirical data shows, for 220kV and above system, zero sequence, negative phase-sequence primary current are greater than 300A, then electrical network there occurs asymmetry fault, and then utilize zero negative sequence directional element to carry out faulty line identification.
Zero sequence positive dirction element:
In formula, zero-sequence current and residual voltage are all self-produced, namely automatically calculate acquisition by A, B, C three-phase current of collecting, voltage, instead of directly collect after outside input.
Negative phase-sequence positive dirction element:
In formula, negative-sequence current and negative sequence voltage are all self-produced.
(2) symmetrical fault (three-phase shortcircuit)
During network system generation symmetrical fault, all without zero negative sequence component, therefore impedance directional element only can be adopted to carry out faulty line identification, Z
aB, Z
aC, Z
bCall should meet criterion is below then positive dirction.
Interphase distance relay adopts the ohm relay of band offset characteristic.Operating criterion is
for memory voltage before fault.
Z
setfixedly can get " circuit positive sequence impedance definite value " z
l11.2 ~ 1.5 times.
After directional element has calculated, all positive dirction circuits are identified at main wiring diagram.If circuit both sides are all shown as positive dirction, then this circuit is then suspected malfunctions circuit, the poor flow valuve of manual calculations circuit both sides fault current again, as difference flow valuve is greater than difference stream setting valve, then this circuit is faulty line, and line fault point location can adopt the hybrid ranging methods such as single end distance measurement, both-end resistance algorithm, travelling wave ranging to carry out trouble spot and accurately locate.
Concrete example:
Case 1: somewhere thunderstorm weather, A stands: 220kV bus bar differential prptection operation, 220kV mother 200A switch, this side II line 213 switch breaking, offside B stands: II line 213 switch breaking.
During fault analysis, can from the relevant range of main separation differential current computing, differential algorithm initiation value and percentage differential element action characteristics curve.Can obviously be found out by Fig. 4, during this fault, bus differential current computing value drops in active region, accurately can judge that bus A phase ground connection occurs and is converted to A, C double earthfault; Circuit non-fault, female differential after send out and far away jump order tripping circuit offside switch.
Case 2: somewhere thunderstorm weather, before fault, the method for operation as shown in Figure 5, and wherein circuit L8 transformer station D side isolating switch is in a point position.During grid collapses, isolating switch three-phase tripping operation in circuit L4 both sides does not overlap, the #1 main transformer high-pressure side of transformer station C and the tripping operation of bus three-phase.
Utilize above-mentioned diagnostic method, the fault recorder data delivering to dispatching terminal on after foundation fault carries out computational analysis, first the fault direction of bus equipment difference flow valuve and tripping operation circuit both sides is calculated respectively, can obtain as calculated, transformer station A, B, C tri-station bus, the equal non-fault of transformer equipment, circuit L4, L7, L8 are suspected malfunctions circuit, then calculate the poor flow valuve (referring to table 1) of suspected malfunctions circuit one by one, accurately can judge that this electric network fault is as A phase earth fault in circuit L8 generating region by table 1.
Table 1 suspected malfunctions circuit differential current computing value
Through site inspection; this fault be circuit L8 end occur A phase earth fault and this circuit transformer station C side isolating switch because of operating mechanism fault cannot the point of isolated fault in time; its breaker fail protection is through setting deferred action tripping #1 main transformer high-pressure side and bus connection switch, and L4 circuit is because of misoperation when miscarrying charging overcurrent protection during normal operation causes external area error and jumping offside isolating switch far away.
During electric network fault, operations staff merely based on numerous discrete failure messages such as isolating switch displacement, fault oscillograph analog quantity, protective device action items, cannot fast, accurately, intuitive judgment nature of trouble.For this key issue of fault quick and precisely identification; novelty proposes a kind of large scale electric network intelligent failure diagnosis method based on differential principle herein; utilize differential principle accuracy of judgement, not by the accurate fault location of peculiar advantage such as system operation mode, transition resistance, load current, power inverted orientation, system diagnostics and the behavior of evaluation protection act; and by the unified displaying directly perceived on main wiring diagram of each interval fault current, abort situation and diagnostic result, for accident treatment provides the decision support of urgent need.This system is accurate failure judgement position in a lot of electric network fault process, for fast recovery of power supply provides the decision support of urgent need, has stronger engineer applied and is worth.
By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.