CN105207187A - Zero-sequence blocking digital current protection method - Google Patents
Zero-sequence blocking digital current protection method Download PDFInfo
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- CN105207187A CN105207187A CN201510734303.0A CN201510734303A CN105207187A CN 105207187 A CN105207187 A CN 105207187A CN 201510734303 A CN201510734303 A CN 201510734303A CN 105207187 A CN105207187 A CN 105207187A
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Abstract
The invention discloses a zero-sequence blocking digital current protection method which comprises the following steps: when in implementation, digital current protection is divided into two parts, namely phase-segregated digital current protection and zero-sequence digital current protection, and meanwhile, the phase-segregated digital current protection and the zero-sequence digital current protection are configured at the same time; when a short-circuit fault current does not contain a zero-sequence current, the zero-sequence digital current protection does not act, and a fault is cut off under the action of the phase-segregated digital current protection; when the short-circuit fault current contains the zero-sequence current, the zero-sequence digital current protection acts and blocks the phase-segregated digital current protection, and a ground fault is cut off under the action of the zero-sequence digital current protection. Through matching of the phase-segregated digital current protection and the zero-sequence digital current protection, the problem that the phase-segregated digital current protection is liable to act by mistake when the high-resistance ground fault occurs can be solved, the protection application range is wider, and the practical value is greater.
Description
Technical field
The present invention relates to a kind of interchange ring network power supply system being applicable to subway, urban light rail and tramcar; and there is the zero sequence enclosed type digital current protection method of electric power system in other field of similar network structure, particularly relate to a kind of zero sequence enclosed type digital current protection method.
Background technology
For the Feeding System of Urban Rail Transit adopting ring string supply power mode, the selectivity of digital current protection is strong, and operate time is short, can be applicable to multiple operational mode, and the application therefore in subway Medium voltage power supply system is more and more extensive.
But along with going deep into of application, digital current protection also shows some shortcomings in application process, needs to improve.Be in particular in, when adjust according to maximum load current phase-splitting digital current definite value and breakdown judge section start definite value, although can ensure the sensitivity protected, when single-phase high-impedance, easily there is misoperation in the protection of phase-splitting digital current.
Fig. 1 is high resistance earthing fault time-division phase digital current false protection reason schematic diagram.In order to ensure the sensitivity protected, in figure, the protection definite value of 102 circuit breakers is adjusted according to 1.5 times of maximum load currents, and phase-splitting current ration is 320A; In figure, 101 and 121 circuit breakers are adjusted according to 1.1 times of maximum load currents, and phase-splitting current ration is respectively 210A and 150A.When bus load reaches 140A as transformer load electric current comparatively greatly; if the high resistance earthing fault within the scope of 103 breaker protections now occurs, and faulted phase current is 200A, and 102 circuit breakers will be caused to be mistaken for troubles inside the sample space; thus misoperation, expand power outage scope.
Reason of false action is as follows: the fault current flowing through 102 circuit breakers be high resistance ground short circuit current and load current and electric current, i.e. 200A+140A=340A, be greater than 102 circuit breaker phase-splitting digital current protection definite value 320A, therefore 102 circuit breaker phase-splitting digital current protections start timing; The fault current flowing through 101 circuit breakers is high resistance ground short circuit current 200A, is less than the 101 circuit breaker failure section of judgement starting current definite value 210A, and therefore 101 protection device for circuit breakers can not send phase-splitting block signal to 102 circuit breakers; The electric current flowing through 121 circuit breakers is load current 140A, is less than the 121 circuit breaker failure section of judgement starting current definite value 150A, and therefore 121 protection device for circuit breakers can not send phase-splitting block signal to 102 circuit breakers.
After 102 circuit breaker phase-splitting digital current protections start timing; do not receive the phase-splitting breakdown judge section enabling signal of adjacent right side 101 and 121 circuit breaker in the 50ms of fixed value adjusting always; therefore failure judgement is positioned at 102 right of circuit breaker protection zones, and trip protection exports, tripping 102 circuit breaker.
And actual high resistance earthing fault is in 103 protection zones, so 102 circuit breakers belong to misoperation, misoperation result in the expansion of power failure range, causes serious threat to the reliability of electric power system.
For on send fault type, also there is no at present ripe solution in open source information.If in conjunction with the design feature of electric power system, a solution can be proposed, will have good Social and economic benef@.
Summary of the invention
Object of the present invention; be to provide a kind of zero sequence enclosed type digital current protection method; this a kind of zero sequence enclosed type digital current protection method effectively can avoid the misoperation of high resistance earthing fault time-division phase digital current protection, and provides effective scheme to excise high resistance earthing fault.
In order to reach above-mentioned purpose, solution of the present invention is: a kind of zero sequence enclosed type digital current protection method, it is characterized in that comprising the following steps: during digital current the protection implement, be divided into the protection of phase-splitting digital current and zero sequence digital current to protect two parts, and configure the protection of phase-splitting digital current and the protection of zero sequence digital current simultaneously; When not containing zero-sequence current in short-circuit current, the protection of zero sequence digital current is failure to actuate, and fault protects excision by phase-splitting digital current; When in short-circuit current containing zero-sequence current time, zero sequence digital current protection act and locking phase-splitting digital current protection, earth fault is excised by zero sequence digital current protection act.
Further; described zero sequence digital current protection is used for locking phase-splitting digital current method and is: after producing zero-sequence current in electric power system; if the zero-sequence fault section of judgement enabling signal is logic "True", then the phase-splitting breakdown judge section enabling signal of same device is forced also to be logic "True".
Further, described digital current protection comprises the following steps: exchange the protective device that in looped network, each circuit breaker configures and send phase-splitting and zero sequence two kinds of breakdown judge section enabling signals by the Web broadcast be interconnected, the definite value of two kinds of signals is independently arranged; Be logic "True" when phase current is greater than the phase-splitting definite value time-division phase fault section of judgement enabling signal, when zero-sequence current is greater than zero sequence definite value, the zero-sequence fault section of judgement enabling signal is logic "True".
Further, described digital current protection comprises the following steps: when phase current is greater than phase-splitting digital current protection definite value, the protection of phase-splitting digital current starts, and receives the phase-splitting breakdown judge section enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then the protection of phase-splitting digital current is blocked and is judged as external area error; Otherwise, through fixed value adjusting delay time phase-splitting digital current protection quick acting outlet excision fault.
Further, described digital current protection comprises the following steps: when zero-sequence current is greater than zero sequence digital current protection definite value, the protection of zero sequence digital current starts, and receives the zero-sequence fault section of the judgement enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then the protection of zero sequence digital current is blocked and is judged as external area error; Otherwise, through fixed value adjusting delay time zero sequence digital current protection quick acting outlet excision fault.
Subway exchanges the protective device that in looped network, each circuit breaker configures and sends phase-splitting and zero sequence two kinds of breakdown judge section enabling signals by Web broadcast, and the definite value of two kinds of signals is independently arranged; Be logical truth when phase current is greater than the phase-splitting definite value time-division phase fault section of judgement enabling signal, when zero-sequence current is greater than zero sequence definite value, the zero-sequence fault section of judgement enabling signal is logical truth.
The action logic of phase-splitting digital current protection is as follows: when phase current is greater than phase-splitting digital current protection definite value, the protection of phase-splitting digital current starts, and receives the phase-splitting breakdown judge section enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then the protection of phase-splitting digital current is blocked and is judged as external area error; Otherwise, through fixed value adjusting delay time phase-splitting digital current protection quick acting outlet excision fault.
The action logic of zero sequence digital current protection is as follows: when zero-sequence current is greater than zero sequence digital current protection definite value, the protection of zero sequence digital current starts, and receives the zero-sequence fault section of the judgement enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then the protection of zero sequence digital current is blocked and is judged as external area error; Otherwise, through fixed value adjusting delay time zero sequence digital current protection quick acting outlet excision fault.
In order to solve the problem of phase-splitting digital current protection easy malfunction when high resistance earthing fault, on the basis of above-mentioned digital current protection scheme, increase following corrective measures, as described in Figure 2:
1) " protection of phase-splitting digital current " and " protection of zero sequence digital current " two parts are divided into during digital current the protection implement; and " protection of phase-splitting digital current " and " protection of zero sequence digital current " must configure simultaneously, to realize excising the protection of whole failure mode.
2) when two-phase and three phase short circuit fault, do not have zero-sequence current in fault current, the protection of zero sequence digital current can not action, and fault protects excision by phase-splitting digital current; When ground short circuit fault, containing zero-sequence current in fault current, now zero sequence digital current protection blocking phase-splitting digital current is protected, and to prevent phase-splitting digital current from protecting misoperation in high resistance ground situation, earth fault protects excision by zero sequence digital current.
3) method of zero sequence digital current protection blocking phase-splitting digital current protection is: after producing zero-sequence current in electric power system; if the zero-sequence fault section of judgement enabling signal is logic "True", then the phase-splitting breakdown judge section enabling signal of same device is forced also to be logic "True".
Because zero-sequence current belongs to fault sequence component electric current, be only detected at the electric power system Shi Caineng that breaks down, its fixed value adjusting is very sensitive, can effectively excise all earth faults comprising high resistance earthing fault.
A kind of zero sequence enclosed type of the present invention digital current protection method, comprises following content: be divided into " protection of phase-splitting digital current " and " protection of zero sequence digital current " two parts when (1) digital current protection method is implemented; (2) when two-phase and three phase short circuit fault, do not have zero-sequence current in electric power system, fault protects excision by phase-splitting digital current; (3) during single-phase grounding fault; zero-sequence current is produced in electric power system; the protection of phase-splitting digital current is blocked, and to prevent phase-splitting digital current from protecting the misoperation when high resistance earthing fault, earth fault excises fault by zero sequence digital current protective seletion.The cooperation that the method is protected by phase-splitting and zero sequence digital current, solves the problem of phase-splitting digital current protection easy malfunction when high resistance earthing fault, and the protection scope of application is wider, has great practical value.
Accompanying drawing explanation
Fig. 1 high resistance earthing fault time-division phase digital current false protection reason schematic diagram;
In figure, protection definite value is phase-splitting digital current protection definite value, is divided into current ration and time definite value; Starting definite value is that the protection of phase-splitting digital current starts definite value, comprises current ration but not free definite value; Bus load is 1 rectifier transformer and Rectification Power Factor.
Fig. 2 zero sequence enclosed type digital current protection method schematic diagram;
Embodiment
See Fig. 1 and Fig. 2, this a kind of zero sequence enclosed type digital current protection method, comprise the following steps: during digital current the protection implement, be divided into the protection of phase-splitting digital current and zero sequence digital current to protect two parts, and configure the protection of phase-splitting digital current and the protection of zero sequence digital current simultaneously; When not containing zero-sequence current in short-circuit current, the protection of zero sequence digital current is failure to actuate, and fault protects excision by phase-splitting digital current; When in short-circuit current containing zero-sequence current time, zero sequence digital current protection act and locking phase-splitting digital current protection, earth fault is excised by zero sequence digital current protection act.
Described zero sequence digital current protection is used for locking phase-splitting digital current method and is: after producing zero-sequence current in electric power system; if the zero-sequence fault section of judgement enabling signal is logic "True", then the phase-splitting breakdown judge section enabling signal of same device is forced also to be logic "True".Described digital current protection comprises the following steps: exchange the protective device that in looped network, each circuit breaker configures and send phase-splitting and zero sequence two kinds of breakdown judge section enabling signals by the Web broadcast be interconnected, the definite value of two kinds of signals is independently arranged; Be logic "True" when phase current is greater than the phase-splitting definite value time-division phase fault section of judgement enabling signal, when zero-sequence current is greater than zero sequence definite value, the zero-sequence fault section of judgement enabling signal is logic "True".Described digital current protection comprises the following steps: when phase current is greater than phase-splitting digital current protection definite value, the protection of phase-splitting digital current starts, and receives the phase-splitting breakdown judge section enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then the protection of phase-splitting digital current is blocked and is judged as external area error; Otherwise, through fixed value adjusting delay time phase-splitting digital current protection quick acting outlet excision fault.Described digital current protection comprises the following steps: when zero-sequence current is greater than zero sequence digital current protection definite value, the protection of zero sequence digital current starts, and receives the zero-sequence fault section of the judgement enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then the protection of zero sequence digital current is blocked and is judged as external area error; Otherwise, through fixed value adjusting delay time zero sequence digital current protection quick acting outlet excision fault.
Below with reference to accompanying drawing 1, technical scheme of the present invention is described in detail.
Realizing digital current defencive function is the basis realizing technical solution of the present invention.Realize digital current protection, first need to set up communication network, to guarantee that the protective device realizing circuit breakers in urban track traffic ring string data electric power system can utilize communication network to realize the quick transmission of signal.Communication network can select GOOSE network, also can be chosen as other network.Specific in accompanying drawing 1, the necessary access communications network of protective device of 101,102,103,121 circuit breakers, and breakdown judge section enabling signal can be transmitted by communication network.
The protective device that in Fig. 1, each circuit breaker configures sends phase-splitting and zero sequence two kinds of breakdown judge section enabling signals by communications network broadcast, and the definite value of two kinds of signals is independently arranged; It is logic "True" that the phase current collected when protective device is greater than the phase-splitting definite value time-division phase fault section of judgement enabling signal; When the zero-sequence current that protective device collects is greater than zero sequence definite value, the zero-sequence fault section of judgement enabling signal is logic "True".
The digital current protection range of each circuit breaker is between this circuit breaker and circuit breakers; Be troubles inside the sample space for the fault in protection range, digital current protection should be tripped excision fault; Be external area error for the fault outside protection range, digital current protection should not be tripped, otherwise is exactly misoperation.For 102 circuit breakers in Fig. 1, on the right side of it, protection range is the bus between 102,101 and 121 3 circuit breakers, and on the left of it, protection range is the power circuit between 100 and 102 circuit breakers.
The action logic of phase-splitting digital current protection is as follows: when phase current is greater than phase-splitting digital current protection definite value, the protection of phase-splitting digital current starts, and in fixed value adjusting delay time, receive the phase-splitting breakdown judge section enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then after definite value delay time, the protection of phase-splitting digital current is blocked and is judged as external area error; Otherwise, phase-splitting digital current protection quick acting outlet excision fault.
The action logic of zero sequence digital current protection is as follows: when zero-sequence current is greater than zero sequence digital current protection definite value, the protection of zero sequence digital current starts, and in fixed value adjusting delay time, receive the zero-sequence fault section of the judgement enabling signal of closing on circuit breaker; Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True"; If two of both sides groups of signals are all logic "True", then after definite value delay time, the protection of zero sequence digital current is blocked and is judged as external area error; Otherwise, zero sequence digital current protection quick acting outlet excision fault.
For 102 circuit breakers in Fig. 1, on the left of it, circuit breakers is 100 circuit breakers; On the right side of it, circuit breakers is 101 and 121 circuit breakers.Because Feeding System of Urban Rail Transit is single supply system, when in generation 102 right of circuit breaker protection zone during AB phase short trouble, phase fault electric current flows through 100 and 102 circuit breakers.Timing is started after 102 circuit breaker phase-splitting digital current protections start; the left and right sides due to 102 only 100 circuit breakers has fault current to flow through; so within the time delay definite value time, 102 circuit breakers only can receive the left side block signal of 100 circuit breaker representatives, and right side does not have block signal all the time.According to action logic, the protection of phase-splitting digital current is judged to be troubles inside the sample space, tripping 102 circuit breaker.
For the fault of 103 right of circuit breakers, to external area error during 102 circuit breaker, when outside generating region during AB phase short trouble, phase fault electric current flows through 100,102 and 101 circuit breakers.Timing is started after 102 circuit breaker phase-splitting digital current protections start; because each side have 100 circuit breakers and 101 circuit breakers of 102 have fault current to flow through; so within the time delay definite value time; 102 circuit breakers can not only receive the left side block signal of 100 circuit breaker representatives, also can receive the right side block signal of 101 circuit breaker representatives.According to action logic, the protection of phase-splitting digital current is judged to be external area error, and protection is failure to actuate.
During earth fault, protective device can not only detect the phase current in electric power system, also can zero-sequence current be detected, and now zero sequence digital current relay protective scheme will drop into automatically.The protection of zero-sequenceprotection logical AND phase-splitting digital current is similar, no longer repeat specification.
After achieving above-mentioned digital current defencive function, continue to realize following combinative movement logic, to realize main contents of the present invention.
1) " protection of phase-splitting digital current " and " protection of zero sequence digital current " two parts are divided into during digital current the protection implement; and " protection of phase-splitting digital current " and " protection of zero sequence digital current " must configure simultaneously, to realize excising the protection of whole failure mode.For 102 circuit breakers in Fig. 1, the protection of phase-splitting digital current and the protection of zero sequence digital current must drop into simultaneously.
2) when two-phase and three phase short circuit fault, do not have zero-sequence current in electric power system, the protection of zero sequence digital current can not action, and fault protects excision by phase-splitting digital current; When ground short circuit fault, produce zero-sequence current in electric power system, now zero sequence digital current protection blocking phase-splitting digital current is protected, and to prevent phase-splitting digital current from protecting misoperation in high resistance ground situation, earth fault protects excision by zero sequence digital current.The reason of false action of phase-splitting digital current protection is see the related description in background technology.
3) method of zero sequence digital current protection blocking phase-splitting digital current protection is: after producing zero-sequence current in electric power system; if the zero-sequence fault section of judgement enabling signal is logic "True", then the phase-splitting breakdown judge section enabling signal of same device is forced also to be logic "True".For 102 circuit breakers in Fig. 1, when there is earth fault in 103 right side region, zero-sequence current flows through 100,101,102 and 103 totally 4 circuit breakers, the phase-splitting breakdown judge section startup definite value of corresponding circuit breaker now whether is greater than regardless of faulted phase current, as long as the zero-sequence fault section of judgement that zero-sequence current is greater than corresponding circuit breaker starts definite value, the phase-splitting of this circuit breaker and the zero-sequence fault section of judgement enabling signal is namely forced to be "True".
Above embodiment is only and technological thought of the present invention is described, can not limit protection scope of the present invention with this, and every technological thought proposed according to the present invention, any change that technical scheme basis is done, all falls within scope.
Claims (5)
1. a zero sequence enclosed type digital current protection method, is characterized in that comprising the following steps:
Be divided into the protection of phase-splitting digital current and zero sequence digital current to protect two parts during digital current the protection implement, and configure the protection of phase-splitting digital current and the protection of zero sequence digital current simultaneously;
When not containing zero-sequence current in short-circuit current, the protection of zero sequence digital current is failure to actuate, and fault protects excision by phase-splitting digital current;
When in short-circuit current containing zero-sequence current time, zero sequence digital current protection act and locking phase-splitting digital current protection, earth fault is excised by zero sequence digital current protection act.
2. zero sequence enclosed type digital current protection method as claimed in claim 1; it is characterized in that the protection of described zero sequence digital current for the method for locking phase-splitting digital current protection is: after producing zero-sequence current in electric power system; if the zero-sequence fault section of judgement enabling signal is logic "True", then the phase-splitting breakdown judge section enabling signal of same device is forced also to be logic "True".
3. zero sequence enclosed type digital current protection method as claimed in claim 1 or 2, is characterized in that described digital current protection comprises the following steps:
Exchange the protective device that in looped network, each circuit breaker configures and send phase-splitting and zero sequence two kinds of breakdown judge section enabling signals by the Web broadcast be interconnected, the definite value of two kinds of signals is independently arranged;
Be logic "True" when phase current is greater than the phase-splitting definite value time-division phase fault section of judgement enabling signal, when zero-sequence current is greater than zero sequence definite value, the zero-sequence fault section of judgement enabling signal is logic "True".
4. zero sequence enclosed type digital current protection method as claimed in claim 1 or 2, is characterized in that the protection of described digital current comprises the following steps:
When phase current is greater than phase-splitting digital current protection definite value, the protection of phase-splitting digital current starts, and receives the phase-splitting breakdown judge section enabling signal of closing on circuit breaker;
Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True";
If two of both sides groups of signals are all logic "True", then the protection of phase-splitting digital current is blocked and is judged as external area error;
Otherwise, through fixed value adjusting delay time phase-splitting digital current protection quick acting outlet excision fault.
5. zero sequence enclosed type digital current protection method as claimed in claim 1 or 2, is characterized in that the protection of described digital current comprises the following steps:
When zero-sequence current is greater than zero sequence digital current protection definite value, the protection of zero sequence digital current starts, and receives the zero-sequence fault section of the judgement enabling signal of closing on circuit breaker;
Be positioned at the left side of protective device according to signal source or right side is divided into two groups, have a signal to be logic "True" if often organized in signal, think that this group signal is logic "True";
If two of both sides groups of signals are all logic "True", then the protection of zero sequence digital current is blocked and is judged as external area error;
Otherwise, through fixed value adjusting delay time zero sequence digital current protection quick acting outlet excision fault.
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