CN1578038A - Protective relay device - Google Patents
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- CN1578038A CN1578038A CN 200410069971 CN200410069971A CN1578038A CN 1578038 A CN1578038 A CN 1578038A CN 200410069971 CN200410069971 CN 200410069971 CN 200410069971 A CN200410069971 A CN 200410069971A CN 1578038 A CN1578038 A CN 1578038A
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Abstract
To prevent unnecessary operations of a differential protective relay by controlling the operation output of a protective device by performing failure detection at a high speed if CT circuit failure occurs at ordinary operation. This protective relay device protects a protection target such as transmission line or a bus-bar by inputting secondary current information of CT installed on each terminal and using a current differential type, and comprises circuits for detecting balancing of three-phase current for each terminal; circuits for detecting imbalance of three-phase current for each terminal; a circuit 131 for detecting any other event than the ordinary operation of the system; and difference current detection circuit 141 for detecting that a vector sum of respective terminal currents for each phase is at least a predetermined value. If balancing of the three-phase current of at least one of the respective terminals is detected, imbalance of the three-phase current of at least one of the respective terminals is detected, any other event than ordinary operation of the system is not detected in the respective terminals, and if it is detected that the vector sum of the respective terminal currents is at least the predetermined value, the CT secondary circuit is determined as being failed.
Description
Technical field
The present invention relates to have the protection relay system of following function, the fault that is about to detect the terminal electric current of electric power system and is input to current transformer in the differential protection (below be called CT) is discerned mutually with the system failure and is detected.
Background technology
As the relay system of existing protection electric power system, many current informations that all adopt based on each terminal carry out the current differential mode of differential protection to object of protections such as transformer, power transmission line or buses.
In the protection relay system of this current differential mode; to object of protection equipment circulation overcurrent the time; if the fault of CT secondary circuit has taken place, particularly broken string and short circuit has taken place; CT secondary current as the input of protective device has just disappeared; only produce spill current, probably can interdict this circuit breaker as the accident of thinking object of protection by mistake by the electric current that flows other terminals.
Yet; CT fault detection method as the protection relay system of electric power system; the known method that the balance that detects electric current arranged (for example; non-patent literature 1 and non-patent literature 2) and the detection accident before and after the changing unit of electric current, when a line ground fault, detect the method (for example patent documentation 1) of CT fault.
[patent documentation 1] spy opens flat 11-346433 communique
No. 4 " digital relay " 65 pages are rolled up in [non-patent literature 1] electric joint research the 41st clear and in January, 61 distribution
[non-patent literature 2] puts down into 106 pages～107 pages that issue electric joint research the 50th volume No. 1 " second generation digital relay " in April, 6
Summary of the invention
In the former protection relay system, for recognition system fault and CT fault, the time of detecting the CT fault needed more than the several seconds, so taking place on the CT circuit under the condition of poor, can not avoid the unnecessary work of protective device.
In the latter's protection relay system, owing to detect the residual circuit of CT or the fault of three secondary circuits, the fault of each circuitry phase of CT does not just become object.In addition, owing to when fault takes place, detect the CT fault, therefore, even only can be applicable in the protective device of the high resistance grounding system that the operating time is late also no problem.
The object of the present invention is to provide a kind of protection relay system, taken place under the situation of CT fault when usual operation, the work output of the control protective device by carrying out fault detect at high speed can prevent the unnecessary work of differential protection relay.
The protection relay system of first invention, input is arranged on the secondary current information of current transformer on each terminal (below be called CT), and utilizes the current differential mode, the object of protection of protection electric power system, have: first device, to the balance of each terminal detection three-phase current; Second device is to the imbalance of each terminal detection three-phase current; The 3rd device, the incident beyond the usual operation of detection system; The 4th installs, and detects the vector situation above with (Id) becoming predetermined value (Ikd) of each terminal electric current of every phase; The 5th device, detect the balance of the three-phase current of at least one terminal in each terminal by above-mentioned first device, detect the imbalance of the three-phase current of at least one terminal in each terminal by above-mentioned second device, and, each terminal all be can't help the incident beyond the usual operation of above-mentioned the 3rd device detection system, to be detected the vector of each terminal electric current by above-mentioned the 4th device and (Id) to become the above situation of predetermined value (Ikd) is condition, is judged to be the fault of CT secondary circuit.
The protection relay system of second invention; in the protection relay system of first invention; above-mentioned first device detects minimum value and the peaked ratio of three-phase current of each terminal more than predetermined value (k); and the maximum of three-phase current is more than predetermined value (Ik); above-mentioned second device detects the minimum value and the not enough predetermined value of peaked ratio (k) of the three-phase current of each terminal; and the maximum of three-phase current is more than predetermined value (Ik), and the current value that above-mentioned the 3rd device detects the maximal phase in the three-phase current of each terminal is more than predetermined value (Ikm) or the Zero-phase current of system.
The protection relay system of the 3rd invention; in the protection relay system of first invention; above-mentioned first device detects minimum value and the peaked ratio of three-phase current of each terminal more than predetermined value (k); and the maximum of three-phase current is more than predetermined value (Ik); above-mentioned second device detects minimum value and the peaked ratio of three-phase current of each terminal below predetermined value (kL); and the maximum of three-phase current is more than predetermined value (Ik), and the current value that above-mentioned the 3rd device detects the maximal phase in the three-phase current of each terminal is more than predetermined value (Ikm) or the Zero-phase current of system.
The protection relay system of the 4th invention in the protection relay system of first invention, utilizes the output of above-mentioned the 5th device, the output of control demonstration and protective device.
The protection relay system of the 5th invention; in the protection relay system of first invention; the current value of the maximal phase in the three-phase current that above-mentioned the 3rd device is each terminal is more than predetermined value (Ikm); perhaps; the neutral point current of transformer (Zero-phase current of system) is more than predetermined value; the current phasor of each terminal of each phase and the electric current of maximal phase, the containing ratio of its high order harmonic component is more than predetermined value (λ).
The protection relay system of the 6th invention, input is arranged on the secondary current information of current transformer on each terminal (below be called CT), and utilizes the current differential mode, the object of protection of protection electric power system, have: first device, to the balance of each terminal detection three-phase current; Second device is to the imbalance of each terminal detection three-phase current; The 3rd device, the incident beyond the usual operation of detection system; The 4th the device, detect every phase each terminal electric current vector and (Id) become more than the predetermined value (Ikd); The 6th device, the above-mentioned the 3rd installs the incident beyond the usual operation of detection system not, and has detected the current phasor of the unbalanced terminal of three-phase current from above-mentioned second device, obtains pseudo-electric current (Ig); The 7th device, detect the spill current (Idm) that obtains by above-mentioned the 4th device with the poor of the same pseudo-electric current mutually that obtains by above-mentioned the 6th device or compare below predetermined value; The 8th device, detect the balance of the three-phase current of at least one terminal in each terminal by above-mentioned first device, detect the imbalance of the three-phase current of at least one terminal in each terminal by above-mentioned second device, and, not detected by the incident beyond the usual operation of above-mentioned the 3rd each terminal system of device, to detect the vector of each terminal electric current by above-mentioned the 4th device and (Id) to be situation more than predetermined value (Ikd), and detecting spill current (Idm) by above-mentioned the 7th device is condition with the difference of pseudo-electric current or than the situation below predetermined value, judges the fault of CT secondary circuit.
The protection relay system of the 7th invention, input is arranged on the secondary current information of current transformer on each terminal (below be called CT), and utilize the current differential mode, the object of protection of protection electric power system, have: suppress the current imbalance checkout gear, detect each terminal electric current of each phase scalar sum (∑ | three-phase imbalance I|); Incident beyond the system exception phenomenon checkout gear, the usual operation of detection system; The spill current checkout gear, detect each phase each terminal electric current vector and (Id) more than predetermined value; Decision maker, detect the three-phase imbalance of scalar sum of each terminal electric current of each phase by above-mentioned inhibition current imbalance checkout gear, detection system is not unusual for said system anomaly checkout gear, and, vector and the situation more than predetermined value with each terminal electric current of having been detected each phase by the spill current checkout gear are condition, are judged to be the fault of CT secondary circuit.
The effect of invention
The present invention can provide a kind of protection relay system, has taken place under the situation of CT fault when usual operation, and by carrying out fault detect at high speed, the work output of control protective device can prevent the unnecessary work of differential protection relay.
The simple declaration of accompanying drawing
Fig. 1 is the system diagram that the present invention is used for the protective device of three-winding transformer.
Fig. 2 is the protection equipment for transformer of expression first execution mode that is suitable for the protection relay system that the present invention relates to and the block diagram of its input current.
Fig. 3 is the structure chart of the treatment circuit in this execution mode of expression.
Fig. 4 is the block diagram of concrete example of the electric current three-phase equilibrium testing circuit of presentation graphs 3.
Fig. 5 is the block diagram of concrete example of the electric current three-phase imbalance testing circuit of presentation graphs 3.
Fig. 6 is other the block diagram of concrete example of the electric current three-phase imbalance testing circuit of presentation graphs 3.
Fig. 7 is the block diagram of concrete example of the system exception phenomenon testing circuit of presentation graphs 3.
Fig. 8 is the block diagram of other concrete example of the system exception phenomenon testing circuit of presentation graphs 3.
Fig. 9 represents in this embodiment, utilizes the block diagram of an example of CT fault detection signal control protection relay output.
Figure 10 represents in this embodiment, utilizes the block diagram of other examples of CT fault detection signal control protection relay output.
Figure 11 A is the figure of example of the power transmission line of expression three terminal structures that the present invention are applicable to the situation in the power transmission line protection relay system.
Figure 11 B is the structure chart that the present invention is applicable to the protector for transmission line in second execution mode of the situation in the power transmission line protection relay system.
Figure 11 C is the structure chart that expression is applicable to the present invention the treatment circuit in second execution mode of the situation in the power transmission line protection relay system.
Figure 12 is illustrated in the spill current comparison circuit of Figure 11, and pseudo-electric current (Ig) is made the block diagram of condition circuit.
Figure 13 is the transmission system figure of two-terminal that is used to illustrate the effect of this execution mode.
Figure 14 is the polar plot of terminal electric current that is used to illustrate the effect of this execution mode.
Figure 15 A is the system construction drawing that is used for the present invention is used for the situation of protection equipment for busbar.
Figure 15 B is the structure chart of protection equipment for busbar that the present invention is used for the situation of protection equipment for busbar.
Figure 16 is a structure chart of similarly representing the treatment circuit of protection equipment for busbar.
Figure 17 is the structure chart of treatment circuit that expression is applicable to the present invention other execution modes of protection equipment for busbar.
Embodiment
Fig. 1 and Fig. 2 are the figure that is used for illustrating respectively first execution mode of the protection relay system that the present invention relates to, and Fig. 1 is the system diagram that is applicable to the situation in the protective device of three-winding transformer, and Fig. 2 is the block diagram of indication transformer protective device and its input current.
In Fig. 1, the 1st, three-winding transformer, high-pressure side winding 1p is connected with mains side by no illustrated circuit breaker, and medium voltage side winding 1s and low-pressure side winding 1t are connected with power transmission line by no illustrated circuit breaker.
Be provided with in the system at such transformer, respectively with power transmission line that high-pressure side winding 1p is connected on be provided with the CT11 that detects high voltage side current, with medium voltage side winding 1s and power transmission line that low-pressure side winding 1t is connected on, be provided with CT12 that detects the medium voltage side electric current and the CT13 that detects the low-pressure side electric current, simultaneously, on the neutral ground circuit of high-pressure side winding 1p and medium voltage side winding 1s, be provided with CT14 that detects the high-pressure side neutral point current and the CT15 that detects the medium voltage side neutral point current respectively.
In Fig. 2; the 21st, protection equipment for transformer; import secondary current Ip and the secondary current Is of medium voltage side CT12 and the secondary current It of low-pressure side CT13 of high-pressure side CT11 respectively to this protection equipment for transformer 21; simultaneously, import secondary current Ipn and the Isn of high-pressure side neutral point CT14 and medium voltage side neutral point CT15 respectively.Protection equipment for transformer 21 is made of the output circuit 161 of CT failure detector circuit 151 and differential relay.The structure of expression CT failure detector circuit 151 among Fig. 3.Handle these secondary current by the treatment circuit of representing among Fig. 3.
Have again, the electric current input that protection equipment for transformer 21 is usually represented in Fig. 2, also import the electric weight of the voltage of low-pressure side and the voltage of medium voltage side etc., but omit its record at this.
In Fig. 3,111,112,113 each detect the circuit of the electric current three-phase equilibrium of high voltage side current, medium voltage side electric current, low-pressure side electric current naturally, 121,122,123 each detect the circuit of the electric current three-phase imbalance of high voltage side current, medium voltage side electric current, low-pressure side electric current naturally, 101, the 102nd, obtain this each 3 groups output logic and OR circuit, the 103rd, obtain the "AND" circuit of logic product of the output of these OR circuits 101,102.
The 131st, the system exception phenomenon testing circuit of usual (normally) phenomenon that does not produce in service of detection system, the 104th, the NOT circuit that the output of this system exception testing circuit 131 is anti-phase, when this NOT circuit 104 has output, be judged as usual operation.
The 141st, from the vector of each terminal electric current and the spill current testing circuit that obtains.
The 105th, obtain the "AND" circuit of logic product of the output of "AND" circuit 103, NOT circuit 104 and spill current testing circuit 141, if the output of this "AND" circuit 105 becomes logical value " 1 ", just be judged to be CT fault (CTF).
At this, describe about the concrete example of above-mentioned electric current three-phase equilibrium testing circuit 111～113, electric current three-phase imbalance testing circuit 121～123 and system exception phenomenon testing circuit 131.
Fig. 4 is the block diagram of electric current three-phase equilibrium testing circuit 111～113.
In Fig. 4,114 is first decision circuits, whether the ratio of minimum phase ([Ia, Ib, Ic] min) and the electric current of maximal phase ([Ia, Ib, Ic] max) of each phase current of CT secondary of judging terminal is more than definite value (k), 115 is second decision circuits, whether the maximal phase ([Ia, Ib, Ic] max) of judging each phase current is more than predetermined value (Ik), the 106th, "AND" circuit when the output of first decision circuit 114 and second decision circuit 115 all is logical value " 1 ", detects three-phase equilibrium.First decision circuit 114 is represented with the ratio of maximal phase by the minimum of electric current, but also can be detected by maximum with minimum difference.Have, k is a unbalanced value of having considered the three-phase current when usual again, for example about 0.8, and Ik is more than the detection sensitivity of protection relay, considers the error of protective device and the value that determines, is the value about 0.1pu (1pu is the transformer rated current).
Fig. 5 is the block diagram of electric current three-phase imbalance testing circuit 121～123.
In Fig. 5, the 114, the 115th, first and second decision circuits identical, the 107th, NOT circuit with Fig. 4, the 108th, "AND" circuit, be false and output logic value " 0 " at first decision circuit 114, second decision circuit 115 is set up and during output logic value " 1 ", is detected three-phase imbalance.
As the other example of above-mentioned electric current three-phase imbalance testing circuit 121～123, the structure of showing in also can constituting among Fig. 6.
In Fig. 6, the 115th, second decision circuit of Fig. 4,116 is the 3rd decision circuits, electric current according to the phase that has produced broken string is substantially equal to zero, judge that the minimum ratio with maximal phase of electric current is whether below predetermined value (kL), the 117th, "AND" circuit when the output of second decision circuit 115 and the 3rd decision circuit 116 all is logical value " 1 ", detects three-phase imbalance.
Fig. 7 is the block diagram of system exception phenomenon testing circuit 131.
In Fig. 7,1311,1312,1313 is first to the 3rd decision circuits, whether each phase current of each terminal of expression is more than predetermined value (Ikm) in the process decision chart 1,1314,1315 is the 4th and the 5th decision circuits, judge the transformer neutral point electric current whether more than predetermined value (Ikn), the 1316,1317, the 1318th, OR circuit.
If first decision circuit 1311～the 5th decision circuit 1315 any establishment wherein is with regard to the detection system anomaly.
Have, the current value that the Ikm consideration does not take place when usual determines, is the value about 2pu (1pu is the transformer rated current) again.The electric current that the transformer neutral point electric current does not take place when being usual, the electric current that takes place when being earth fault.Ikn is the value about 0.1pu (1pu is the transformer rated current).
This example is the system exception phenomenon testing circuit when having considered tranformer protection; under the situation of having considered power transmission line protection and bus protection, also can be to use the fault detection relay that used terminal voltage and busbar voltage etc., the detection system method of the phenomenon that does not take place in service usually.
Other example as said system anomaly testing circuit 131 also can constitute the structure shown in Fig. 8.
In this example, as shown in Figure 8, be provided with the 6th decision circuit 1316, be used for detection and be included in the higher harmonic current of spill current (Idm) and import its judgement output to OR circuit 1318, in addition identical with Fig. 7, its explanation of Therefore, omited.
At this, if the ratio of electric current (I2fo) and fundamental current (Ifo) of 2 overtones bands (2fo) that is included in the first-harmonic (fo) in the spill current (Idm) is more than predetermined value (λ), the 6th decision circuit 1316 just is judged to be the system exception phenomenon.
The purpose that is provided with the 6th decision circuit 1316 is, the spill current that has produced when CT is saturated has the big feature of 2fo electrorheological, prevent that 2 times of harmonic waves (2fo) electric current that comprises from comprising under certain situation more than the value of fundamental current in spill current, and with it as the CT saturation detection, and flase drop is surveyed and to be the CT fault.
For example, externally during three phase short circuit fault, it is saturated that CT takes place on certain terminal, do not taking place on other terminals under the saturated situation of CT, produced saturated terminal, with in the electric current three-phase imbalance testing circuit of representing among Fig. 3 121～123 any, detect three-phase imbalance, and do not produce saturated terminal, with in the electric current three-phase equilibrium testing circuit 111～113 any, detect three-phase equilibrium, in addition, might work by spill current testing circuit 141 because CT is saturated, just detection is the CT fault.Therefore, detect 2 times of harmonic currents that comprise in the spill current, just detect the fault of having followed CT saturated, and the detection of locking CT fault.
The following describes the work of the protection equipment for transformer 21 that constitutes as mentioned above.
Flow through load current during usual the operation, and load current is the electric current after the three-phase equilibrium.Thereby electric current three-phase equilibrium testing circuit 111,112,113 detects three-phase equilibrium respectively, and its output equals logical value " 1 ".But at this moment, electric current three-phase imbalance testing circuit 121,122,123 does not also detect three-phase imbalance respectively, and therefore, its output is logical value " 0 ".
Thereby "AND" circuit 105 is false owing to its logic product condition, so do not carry out the judgement of CT fault.
Below, describe about the situation that broken string has taken place on the CT11 of high-pressure side.
If on the CT11 of high-pressure side, break during load current, the balance of the three-phase current of the CT secondary current of its high-pressure side terminal is just destroyed, but the CT secondary current of the CT secondary current of other medium voltage side terminal, low-pressure side is keeping the balance of three-phase current.In addition, at this moment, the output of on high-tension side uneven testing circuit 121 becomes logical value " 1 ".Thereby the output of the electric current three-phase equilibrium testing circuit 112,113 of the output of on high-tension side uneven testing circuit 121 and medium voltage side, low-pressure side becomes logical value " 1 ", and therefore, the logic product condition of "AND" circuit 103 is set up.
Because the broken string of the CT the when broken string of this high-pressure side CT11 is usual, system exception testing circuit 131 is not worked, and therefore, the output of NOT circuit 104 is logical value " 1 ".
In addition, because the CT secondary current of high-pressure side terminal does not flow because of the broken string of high-pressure side CT11, therefore, the vector of the electric current of each terminal and electric current are that spill current (Id) only produces the load current part, and the output of spill current testing circuit (Id) 141 becomes logical value " 1 ".
Thereby in the "AND" circuit 105, the output of the output of the output of "AND" circuit 103, NOT circuit 104 and spill current testing circuit (Id) 141 all becomes logical value " 1 ", and therefore, the logic product condition is set up, and detects the CT fault.
The following describes the reaction (servo-actuated) in the outside accident of transformer.
Externally in the accident, the above electric current of transformer rated current passes through terminal usually.Under this situation, do not allow spill current detect 141 work of (Id) circuit, system exception phenomenon testing circuit 131 carries out work.
Thereby, do not detect the CT fault.In addition, if under the situation that the error current of CT is big in the outside accident of transformer (for example having produced the saturated situation of CT), 141 work of spill current testing circuit, but system exception phenomenon testing circuit 131 work, its output is anti-phase by NOT circuit 104, therefore, do not satisfy the logic product condition of "AND" circuit 105, the detection signal of CT fault get clogged (Block ロ Star Network).
Below, excitatory ballistic kick electric current flows when connecting transformer, but describes about the reaction (servo-actuated) of this situation.
If the circuit breaker of energized side, just to the excitatory ballistic kick electric current of high pressure effluent, electric current three-phase imbalance testing circuit 121 carries out work.But medium voltage side, low-pressure side circuit breaker are opened, and do not flow electric current.Therefore, owing to do not carry out balance detection in electric current three-phase equilibrium testing circuit 112,113, so do not satisfy the logic product condition of "AND" circuit 103, the detection of CT fault gets clogged.
As mentioned above, according to present embodiment, can when the CT fault have taken place, inerrancy and detect this CT fault apace.
Below, utilize Fig. 9, in the above-mentioned protection equipment for transformer 21, utilize the example of CT fault detection signal control protection relay output to describe.
In Fig. 9, the 151st, the CT failure detector circuit utilizes the circuit of representing among Fig. 1 to Fig. 3 to constitute and detects.The 161st, the output of protective device under the situation of tranformer protection, is the output circuit of differential relay.The 1511st, NOT circuit under the situation that has detected the CT fault, is used for the output of locking differential relay.The 1611st, "AND" circuit, if the logic product condition is just satisfied in the work output of input differential relay, output does not disconnect (ト リ Star プ) instruction when also not detecting the CT fault.
Thereby if constitute in this wise, output that just can enough CT failure detector circuits 151 shows and reports to the police, exports when not setting up the output of generation differential relay at it.
In the circuit of the protection relay output of control said structure, for example, also can at the outlet side of NOT circuit 1511 as shown in figure 10 switch SW be set, can in the output of differential relay, can select to use or do not use the CT fault condition.
Below, describe about second execution mode of the present invention that in protector for transmission line, has been suitable for the protection relay system that the present invention relates to.
Figure 11 A is the example of the power transmission line of three terminal structures.In Figure 11 B, the 51st, protector for transmission line imports each terminal electric current I A, IB, IC to this protector for transmission line 51.Protector for transmission line 51 is made of the output circuit 161A of CT failure detector circuit 151A and differential relay.
Represented to be arranged on protector for transmission line 51 on the A terminal at this, do not had diagram but same protector for transmission line is being set on each terminal.
The protector for transmission line of using to the A terminal 51 directly imports the electric current I A of A terminals; but the electric current I B of B terminal, C terminal, IC generally use between the fiber optic cables jockey; receive and dispatch the current data of each terminal; implement differential operational; perhaps utilize transfer of data, carry out the transmitting-receiving of current data etc., but all be general technology by communicator; at this, omitted the diagram and the explanation of the receiving/transmission method of current data.
Figure 11 C represents the structure of CT failure detector circuit 151A, and mark prosign on the part identical with Fig. 3 omits its explanation.Have again, in Figure 11 C, show electric current three-phase equilibrium testing circuit 111～113 and electric current three-phase imbalance testing circuit 121～123 with the situation of three terminal systems.
The differential protection of power transmission line need be to each terminal transmission current data, but as differential protection, and the practical current differential protection relay system of PCM mode is suitable for and implements the present invention and be out of question.
The power transmission line protection is different with transformer, and the CT rated current is big, and it is big that load current also becomes thereupon, in high sensitivity the current sensitivity of initialization system anomaly testing circuit 131.In addition, owing to used the Zero-phase current of CT secondary retained circuit to detect, when the CT fault, also produced Zero-phase current, so can not discern mutually with the system failure, in addition, can not use the neutral point current shown in the 4th and the 5th decision circuit 1314,1315 of Fig. 7 in this wise as transformer.
Therefore, in order to discern fault and CT fault, under the situation that three-phase equilibrium and three-phase imbalance are set up, it is effective that puppet (simulation) electric current (Ig) that uses balanced terminals electric current never to make detects the method that CT breaks.
In Figure 11 C, spill current comparison circuit 171 is set, carry out the comparison of the pseudo-electric current (Ig) that spill current (Id) and the electric current from the current imbalance terminal make, detect its difference or than whether below predetermined value (Ikd), and its output is input in the "AND" circuit 105.
Figure 12 makes condition circuit at pseudo-electric current (Ig) shown in the spill current comparison circuit 171 of Figure 11 C, 116,115 is identical with second, third decision circuit of Fig. 6, the 118th, pseudo-electric current is made circuit, when current imbalance, for example, be under zero the situation at a phase current only, make pseudo-electric current from other the biphase current except a phase current.
Figure 13 and Figure 14 are the figure that is used to illustrate the comparison of mechanism that this puppet electric current is made and spill current Ida.Figure 13 is the power transmission line system diagram, and is all identical in three terminals and two-terminal, but in order to make explanation uncomplicated, illustrates with two-terminal, the case of internal fault, and each terminal all flow into the direction stream electric current in the guard interval in the same way.
Figure 14 (a) is the example that the CT broken string of a phase has taken place on the B terminal, shows the current phasor separately of A terminal, B terminal.Figure 14 (b) is the example that the CT broken string of bc phase has taken place on the B terminal, shows the current phasor separately of A terminal, B terminal.
The a of the medium and small literal of current phasor, b, c represent phase, and A, the B of daimonji represent terminal.In addition, with the vector of each terminal electric current with obtain spill current, be expressed as Id.Among Figure 14 (a), the spill current of each phase when the CT secondary circuit a of B terminal breaks mutually becomes
Ida＝Ia
A+Ia
B＝Ia
A
Idb＝Ib
A+Ib
B＝0
Idc＝Ic
A+Ic
B＝0
In addition, in the B terminal, three-phase imbalance is set up.Ib from B terminal electric current
B, Ic
BTwo-phase, make pseudo-electric current I ga and be
‘Iga’＝-(Ib
B+Ic
B)
In spill current comparison circuit 171, carry out the comparison of this Iga and a that spill current is taking place spill current Ida mutually.
Ida+‘Iga’＜ko·Ida
If the CT broken string, then about equally, if systematic failures, then Iga is different with Ida in phase reversal for Iga and Ida.
The situation that CT secondary circuit two-phase that Figure 14 (b) shows the B terminal has broken.Under this situation, produce two-phase at spill current Id.In addition, B terminal current imbalance is set up, and the electric current of a phase is big, flows through electric current hardly but remain two phases.
Ida＝Ia
A+Ia
B＝0
Idb＝Ib
A+Ib
B＝Ib
A
Idc＝Ic
A+Ic
B＝Ic
A
Therefore, a phase current of B terminal electric current is made advance 120 degree and 120 puppet (simulation) electric currents of spending that lag behind,
‘Igb’＝‘Ia
B’＜240°
‘Igc’＝‘Ia
B’＜120°
In spill current comparison circuit 171, carry out respectively with b mutually, the comparison of the spill current of c phase.
Idb+‘Igb’＜ko·Idb
Idc+‘Igc’＜ko·Idc
If CT broken string, then spill current Id and pseudo-electric current I g equal and opposite in direction on phase reversal, therefore, spill current comparison circuit 171 is set up, detection CT fault.
Utilize such structure, can discern CT fault and fault, can detect the CT fault exactly.
It more than is the explanation that the present invention has been applicable to the situation in the protection relay system of protecting transformer and power transmission line.
The present invention is not limited to this, also goes in the bus protection relay system with the bus of differential principle protection electric power system.
Below, be applicable to that about the protection relay system that will the present invention relates to the 3rd execution mode of the present invention in the protection equipment for busbar describes.
Figure 15 A is the system construction drawing of bus, and the example that each terminal 1～terminal N is connected with bus is shown.In Figure 15 B, the 61st, protection equipment for busbar imports each terminal electric current I 1～IN to this protection equipment for busbar 61.Protection equipment for busbar 61 is made of the output circuit 161B of CT failure detector circuit 151B and differential relay.
At this; each terminal electric current I 1～IN is generally by being arranged on the CT on each terminal 1～N; directly import in the protection equipment for busbar with cable; implement differential operational; but the CT secondary current is transformed to light, also practical by the structure that optical cable imports in the protection equipment for busbar, but at this; because the method that explanation imports is not main meaning, Therefore, omited diagram and its explanation.
Figure 16 is the structure chart of treatment circuit that the CT failure detector circuit 151B of protection equipment for busbar 61 is shown.
In Figure 15 A, by there not being illustrated circuit breaker, be connected power transmission line L1～Ln with bus 101 respectively, CT is set respectively on each power transmission line, take out the electric current that flows to each terminal 1～N, as CT secondary current I1～IN.
In Figure 16,111～11N is the electric current three-phase equilibrium testing circuit of current balance type of each terminal of detection terminal 1～terminal N, and 121～12N is the electric current three-phase imbalance testing circuit that detects current imbalance, all describes with Fig. 3.
In addition, other system exception phenomenon testing circuit 131 and spill current testing circuit 141 also have and the same function that illustrates with Fig. 3.
Utilize such structure, can discern CT fault and busbar fault, can detect the CT fault exactly.
In addition, in the protector for transmission line 51 shown in above-mentioned Figure 11 B, count to N,, obtain same effect as protection equipment for busbar by extended terminal.
That is, as can be known, in protection equipment for transformer and protector for transmission line, number of terminals is illustrated as 3, but,, obtains above-mentioned same effect by number of terminals is extended to N as bus protection.
Figure 17 illustrates the structure chart that the present invention is applicable to the treatment circuit of other execution modes in the protection equipment for busbar.
In Figure 17, because NOT circuit 104, "AND" circuit 105, system exception phenomenon testing circuit 131, spill current testing circuit 141, identical with shown in Fig. 3, its explanation of Therefore, omited.
Bus protection generally adopts with the vector of each terminal electric current with as spill current (Id), and the scalar sum of each terminal electric current as amount of suppression (∑ I), from the magnitude relationship of spill current and amount of suppression, is detected the internal fault of bus.
Therefore, in Figure 17, be provided with and suppress current imbalance testing circuit 1111, be used for the amount of suppression ∑ I of each phase of using in the protection computing of bus protection, detect the imbalance of three-phase, with its output as decision condition.
With the summation of the absolute value of a phase of each terminal electric current, obtain the amount of suppression ∑ Ia of a phase, other can be tried to achieve with following formula respectively mutually similarly.
∑Ia＝|Ia1|+|Ia2|+......+|IaN|
∑Ib＝|Ib1|+|Ib2|+......+|IbN|
∑Ic＝|Ic1|+|Ic2|+......+|IcN|
The imbalance of amount of suppression detects, can utilize following formula, whether the minimum value ([∑ Ia, ∑ Ib, ∑ Ic] min) that detects the amount of suppression of each phase and the ratio of the maximum ([∑ Ia, ∑ Ib, ∑ Ic] max) of each amount of suppression mutually be below predetermined value (ky), and, can be that condition detects more than predetermined value with maximum ([∑ Ia, ∑ Ib, ∑ Ic] max).
[∑Ia、∑Ib、∑Ic]min/[∑Ia、∑Ib、∑Ic]max≤ky
This is to replace each phase current in Fig. 6, has been suitable for the amount of suppression of each phase, so structure is also identical.In addition, as the structure of Fig. 5, also can detect imbalance.
As described above; in protection equipment for transformer and protector for transmission line; utilize the maximum of each phase current and the magnitude relationship of minimum value; each terminal is detected balancedunbalanced; but because in bus protection; number of terminals is many, so also can access above-mentioned same effect by being replaced into the amount of suppression of each phase of having used each terminal electric current.
The explanation of Reference numeral
1 ... three-winding transformer
11～15…CT
21 ... protection equipment for transformer
51 ... protector for transmission line
61 ... busbar protective device
101,102 ... OR circuit
103,105 ... "AND" circuit
104 ... NOT circuit
111～113 ... the current three-phase balance detection circuit
121～123 ... the uneven testing circuit of current three-phase
131 ... system exception phenomenon testing circuit
141 ... the spill current testing circuit
151 ... the CT failure detector circuit
161 ... the differential relay output circuit
171 ... the spill current comparison circuit
1111 ... suppress the current imbalance testing circuit
Claims (7)
1. a protection relay system is imported and is arranged on the secondary current information of the current transformer (CT) that carries out on each terminal, and utilizes the current differential mode, object of protection to electric power system is protected, it is characterized in that having: first device, to the balance of each terminal detection three-phase current; Second device is to the imbalance of each terminal detection three-phase current; The 3rd device, the incident beyond the usual operation of detection system; The 4th installs, and detects the vector situation above with (Id) being predetermined value (Ikd) of each terminal electric current of every phase; The 5th device, detect the balance of the three-phase current of at least one terminal in each terminal by above-mentioned first device, detect the imbalance of the three-phase current of at least one terminal in each terminal by above-mentioned second device, and, each terminal all be can't help the incident beyond the usual operation of above-mentioned the 3rd device detection system, to be detected the vector of each the terminal electric current situation above with (Id) being predetermined value (Ikd) by above-mentioned the 4th device is condition, is judged to be CT secondary circuit fault.
2. protection relay system as claimed in claim 1; it is characterized in that; the minimum value that above-mentioned first device detects the three-phase current of each terminal is more than predetermined value (k) with peaked ratio; and the maximum of three-phase current is more than predetermined value (Ik); the minimum value that above-mentioned second device detects the three-phase current of each terminal is not enough predetermined value (k) with peaked ratio; and the maximum of three-phase current is more than predetermined value (Ik), and the current value of the maximal phase in the three-phase current of above-mentioned the 3rd each terminal of device detection is more than predetermined value (Ikm) or the Zero-phase current of system.
3. protection relay system as claimed in claim 1; it is characterized in that; above-mentioned first device detects minimum value and the peaked ratio of three-phase current of each terminal more than predetermined value (k); and the maximum of three-phase current is more than predetermined value (Ik); the minimum value that above-mentioned second device detects the three-phase current of each terminal is below predetermined value (kL) with peaked ratio; and the maximum of three-phase current is more than predetermined value (Ik), and the current value that above-mentioned the 3rd device detects the maximal phase in the three-phase current of each terminal is more than predetermined value (Ikm) or the Zero-phase current of system.
4. protection relay system as claimed in claim 1 is characterized in that, utilizes the output of above-mentioned the 5th device, the output of control demonstration and protective device.
5. protection relay system as claimed in claim 1; it is characterized in that; the current value of the maximal phase in the three-phase current that above-mentioned the 3rd device is each terminal is more than predetermined value (Ikm); perhaps the neutral point current of transformer (Zero-phase current of system) is more than predetermined value; the current phasor of each terminal of each phase and the electric current of maximal phase, the containing ratio of its high order harmonic component is more than predetermined value (λ).
6. a protection relay system is imported and is arranged on the secondary current information of the current transformer (CT) on each terminal, and utilizes the current differential mode, object of protection to electric power system is protected, it is characterized in that having: first device, to the balance of each terminal detection three-phase current; Second device is to the imbalance of each terminal detection three-phase current; The 3rd device, the incident beyond the usual operation of detection system; The 4th device, detect every phase each terminal electric current vector and (Id) be more than predetermined value (Ikd); The 6th device, the above-mentioned the 3rd installs the not usual operation incident in addition of detection system, but is from the current phasor of the unbalanced terminal of the detected three-phase current of above-mentioned second device, obtains pseudo-electric current (Ig); The 7th device, detect the spill current (Idm) that obtains by above-mentioned the 4th device with the poor of the same pseudo-electric current mutually that obtains by above-mentioned the 6th device or compare below predetermined value; The 8th device, detect the balance of the three-phase current of at least one terminal in each terminal by above-mentioned first device, detect the imbalance of the three-phase current of at least one terminal in each terminal by above-mentioned second device, and, not detected by the incident beyond the usual operation of above-mentioned the 3rd each terminal system of device, to detect the vector of each terminal electric current by above-mentioned the 4th device and (Id) to be situation more than predetermined value (Ikd), and detect the poor of spill current (Idm) and pseudo-electric current by above-mentioned the 7th device, perhaps, judge CT secondary circuit fault than being that situation below predetermined value is a condition.
7. protect relay system for one kind, input is arranged on the secondary current information of the current transformer (CT) on each terminal, by the current differential mode, object of protection to electric power system is protected, it is characterized in that, have: suppress the current imbalance checkout gear, detect each terminal electric current of each phase scalar sum (∑ | three-phase imbalance I|); Incident beyond the system exception phenomenon checkout gear, the usual operation of detection system; The spill current checkout gear, detect each phase each terminal electric current vector and (Id) be for more than the predetermined value; Decision maker, detect the three-phase imbalance of scalar sum of each terminal electric current of each phase by above-mentioned inhibition current imbalance checkout gear, detection system is not unusual for said system anomaly checkout gear, and, with the vector of each terminal electric current of having detected each phase by the spill current checkout gear be that situation more than the predetermined value is a condition, be judged to be CT secondary circuit fault.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003276013A JP4199065B2 (en) | 2003-07-17 | 2003-07-17 | Protective relay device |
| JP276013/2003 | 2003-07-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1578038A true CN1578038A (en) | 2005-02-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200410069971 Pending CN1578038A (en) | 2003-07-17 | 2004-07-16 | Protective relay device |
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| JP (1) | JP4199065B2 (en) |
| CN (1) | CN1578038A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101278452B (en) * | 2005-08-30 | 2010-10-13 | Abb技术有限公司 | Method and system for through fault detection in electrical devices |
| CN106771812A (en) * | 2016-12-29 | 2017-05-31 | 许继集团有限公司 | A kind of recognition methods of transformer current transformer disconnection and device |
| CN106771838A (en) * | 2016-12-29 | 2017-05-31 | 许继集团有限公司 | Transformer CT broken strings method of discrimination, device and differential protecting method, device |
| CN112098898A (en) * | 2020-09-22 | 2020-12-18 | 国网四川省电力公司眉山供电公司 | Disconnection fault judgment method and device and regulation and control system |
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| GB2423424B (en) * | 2005-02-22 | 2009-10-28 | Areva T & D Uk Ltd | A method and an apparatus for supervising the operation of current transformers |
| CN102280855B (en) * | 2011-07-18 | 2014-05-28 | 重庆电力高等专科学校 | Protection method of transformer during no-load closing |
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| CN105977914B (en) * | 2016-06-08 | 2018-06-26 | 上海思源弘瑞自动化有限公司 | The method and device of transformer zero-sequencedirectional protection under interior bridge mode |
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2003
- 2003-07-17 JP JP2003276013A patent/JP4199065B2/en not_active Expired - Fee Related
-
2004
- 2004-07-16 CN CN 200410069971 patent/CN1578038A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101278452B (en) * | 2005-08-30 | 2010-10-13 | Abb技术有限公司 | Method and system for through fault detection in electrical devices |
| CN106771812A (en) * | 2016-12-29 | 2017-05-31 | 许继集团有限公司 | A kind of recognition methods of transformer current transformer disconnection and device |
| CN106771838A (en) * | 2016-12-29 | 2017-05-31 | 许继集团有限公司 | Transformer CT broken strings method of discrimination, device and differential protecting method, device |
| CN106771812B (en) * | 2016-12-29 | 2019-05-14 | 许继集团有限公司 | A kind of transformer current transformer disconnection recognition methods and device |
| CN106771838B (en) * | 2016-12-29 | 2019-09-13 | 许继集团有限公司 | Transformer CT broken string method of discrimination, device and differential protecting method, device |
| CN112098898A (en) * | 2020-09-22 | 2020-12-18 | 国网四川省电力公司眉山供电公司 | Disconnection fault judgment method and device and regulation and control system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4199065B2 (en) | 2008-12-17 |
| JP2005039956A (en) | 2005-02-10 |
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