CN105119256B - Prevent power network distance protection first start after decompression malfunction method - Google Patents
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Abstract
The present invention relates to it is a kind of prevent power network distance protection first start after decompression malfunction method; for the distance protection equipment in power network due to external area error and after starting; judge whether that threephase potential transformer secondary circuit broken string occurs, so as to prevent distance protection equipment malfunction, this method is：Continuous n sampled point meets following criterion：1. the voltage jump amount of any one phase is more than the voltage jump threshold value of setting；2. the three-phase voltage calculated using half cycle algorithm is respectively less than 2V；3. three-phase current Sudden Changing Rate is respectively less than the startup definite value of distance protection equipment in 20ms；Wherein n is positive integer；Then judge threephase potential transformer broken string occurs；Distance protection equipment malfunction is prevented according to result of determination.It after distance protection startup can be judged whether that threephase potential transformer broken string occurs by this method, and then avoid distance protection malfunction, improve the security of system.
Description
Technical field
The invention belongs to dispatching of power netwoks control field, and in particular to a kind of distance protection equipment in power network is used for after starting
Prevent voltage transformer disconnection from causing the method for malfunction.
Background technology
Distance protection is using electric current as actuating quantity, and voltage is protected for the deficient amount formula of braking amount.After voltage transformer disconnection
When losing voltage braking amount, measurement impedance is intended to zero, and distance protection will through fault current or load current effect outside area
Lower malfunction.The widely used method for preventing malfunction of distance protection at present is to carry out voltage transformer disconnection decompression differentiation, generally
It is not zero with three-phase voltage vector sum to detect a phase or two-phase voltage transformer disconnection；Detected with the low method of positive sequence voltage
Threephase potential transformer breaks, and general delay 1-2s latch-up protections simultaneously send alarm signal, and typically self-healing.It is above-mentioned
The premise of criterion is that protection device does not start.Generally believe at present once system jam, starting element start after just no longer
Sentence voltage transformer disconnection because any failure all has voltage transformer disconnection feature, do not consider the system failure with
The simultaneous situation of voltage transformer disconnection.
However, practical operation situation shows, the system failure and the definitely simultaneous possibility of voltage transformer disconnection are very
It is small, but because the inducement of the system failure causes the accident of voltage transformer disconnection occurs but in succession (after 20ms) in a short time
Repeatedly occur, and cause the multi circuit transmission lines distance protection malfunction with bus run, serious threat system safety operation.
The situation analysis of voltage transformer disconnection false protection is as follows after distance protection first starts：
1st, double bus scheme transformer station as shown in Figure 1, circuit 1,2,3,4 are system interconnection, double-bus paired running,
When I bus-bar potential transformer overhauls, in general operation method be two groups of bus-bar potential transformer secondary voltage circuits are arranged side by side,
So that the distance protection of circuit 1,2,3,4 is all using II bus-bar potential transformer secondary voltage.But now if II bus occurs
Failure, the distance protection of circuit 1,2,3,4 can all start, and cut off all elements of II bus when bus protection acts, will cause I bus
The distance protection of upper circuit 1,2 loses measurement voltage upon actuation, because protection device starts time broadening typically in 5-7s, this
When load current effect under circuit 1,2 distance protection exist malfunction may, the risk for causing whole station dead electricity be present.Together
Reason, if trouble point on circuit 1 or the outlet of circuit 2, but during wire-outgoing breaker tripping, also leads to same consequence.
2nd, the voltage transformer disconnection of intermittence also leads to miss in the case of decompression after circuit distance protection formerly starts
It is dynamic.Voltage transformer caused by scene is frequently encountered the loosening of voltage secondary circuit terminal screw or secondary line loose contact breaks
Line, sometimes this broken string phenomenon cut in and out, intermittence occurs, if this time zone outgoing life failure, distance protection start after again between
Voltage transformer disconnection occurs for gap, then malfunction under related circuit distance protection will act in the short circuit current for passing through property,
Even if external area error is removed, during protection device starts broadening, the voltage transformer of intermittence breaks under load current effect
Line is still such that the risk of malfunction be present in distance protection.
3rd, bus-bar potential transformer secondary voltage circuit, which is typically both needed to setting, prevents voltage transformer secondary to a reversely charging
The voltage of electricity moves loop again, and it is real that auxiliary reclay is typically moved in the loop again with the normally opened auxiliary contact driving of voltage transformer disconnecting link
Existing, when voltage transformer is out of service, when one time disconnecting link is opened, relay release, secondary voltage circuit breaks with voltage transformer
Open；When voltage transformer puts into operation, one time disconnecting link closes, and the heavy motor type relay excitation, secondary voltage circuit automatically accesses electricity
Press transformer secondary side.Weight motor type relay working power uses the power supply of transformer station direct current system.The operation of the electric power loop can
The protection equipment reliability of operation using bus-bar potential transformer voltage is directly connected to by property, distance protection stands in the breach.
The DC supply that multiple generation voltage moves loop again in actual motion loses in succession after primary system breaks down, mainly
Reason, direct current caused by direct current signal loop fault is spaced apart tripping operation of bypassing the immediate leadership after having plenty of primary system failure, has plenty of system event
Direct current caused by external disturbance during barrier is spaced apart tripping operation, and straight-flow system battery floating charge source loses after having plenty of the system failure,
Dc source caused by battery open circuit loses.Primary system failure turns into the direct inducement of secondary straight-flow system dead electricity, such a
In the case of with the distance protection of bus run the risk of malfunction all be present, certain megapolis urban district one 220kV becomes within 2007
Power station whole station dead electricity, its reason are exactly that the short circuit of direct current signal loop causes direct current sky to be bypassed the immediate leadership tripping operation after the 110kV system failures in standing,
So that 220kV voltage transformer secondary is moved after power supply loses again, the distance protection of four times 220kV power circuits is lost upon actuation
Go to measure voltage, under load current effect caused by successive tripping.Accident loads loss is serious, and lesson is painful.
In summary, although the probability that distance protection first starts the situation generation for losing measurement voltage afterwards does not include too greatly,
It is once generation is often the successive malfunction of a plurality of circuit distance protection with bus run, the risk of whole station dead electricity is present, after
Fruit serious threat system safety.Therefore it is necessary to set about being taken precautions against on protection philosophy, it is necessary to propose protection of adjusting the distance
Voltage transformer disconnection criterion carries out perfect so that and distance protection continues to differentiate voltage transformer disconnection upon actuation,
Distance protection malfunction when preventing external area error.
The content of the invention
After starting it is an object of the invention to provide one kind for distance protection equipment, prevent due to three-phase voltage mutual inductance occurs
Device breaks and causes the method for malfunction.
To reach above-mentioned purpose, the technical solution adopted by the present invention is：
It is a kind of prevent power network distance protection first start after decompression malfunction method, for the distance protection equipment in power network
After due to external area error starting, judge whether that threephase potential transformer secondary circuit broken string occurs, so as to prevent it is described away from
From protection device malfunction, this method is：Continuous n sampled point meets following criterion：
1. the voltage jump amount of any one phase is more than the voltage jump threshold value of setting；
2. the three-phase voltage calculated using half cycle algorithm is respectively less than 2V；
3. three-phase current Sudden Changing Rate is respectively less than the startup definite value of described distance protection equipment in 20ms；
Wherein n is positive integer；
Then judge threephase potential transformer broken string occurs；
Described distance protection equipment malfunction is prevented according to result of determination.
Described voltage jump threshold value is more than voltage jump amount during minimum cycle of oscillation.
Described minimum cycle of oscillation is 200ms.
Further, voltage jump amount when described voltage jump threshold value is described minimum cycle of oscillation is with floating
Threshold sum.
Further, voltage jump amount of the described voltage jump threshold value in described minimum cycle of oscillation is with floating
Increase setting nargin is formed on the basis of threshold sum.
Described voltage jump threshold value is 0.4Un, wherein UnFor voltage rating.
N values are 3.
Because above-mentioned technical proposal is used, the present invention has following advantages compared with prior art：Can be with by this method
After distance protection startup, threephase potential transformer broken string whether occurs after judging 20ms, and then avoids distance protection malfunction, carries
The security of high system.
Brief description of the drawings
Accompanying drawing 1 is the wiring schematic diagram of double bus scheme transformer station.
Accompanying drawing 2 is the criterion theory diagram of the method for the present invention.
Embodiment
With reference to embodiment, the invention will be further described.
Embodiment one：It is a kind of prevent power network distance protection first start after decompression malfunction method, this method be used in power network
In distance protection equipment due to external area error and after starting, threephase potential transformer secondary circuit whether occurs after judging 20ms
Decompression caused by broken string, so as to prevent distance protection equipment malfunction, specifically, this method is：Continuous n (n is positive integer,
Generally take 3) sampled point meet following criterion, that is, judge threephase potential transformer broken string occurs, and then can be according to judgement
As a result distance protection equipment malfunction is prevented.
Criterion includes following three conditions, need to meet simultaneously：
1. the voltage jump amount of any one phase is more than the voltage jump threshold value of setting；
2. the three-phase voltage calculated using half cycle algorithm is respectively less than 2V；
3. three-phase current Sudden Changing Rate is respectively less than the startup definite value of distance protection equipment in 20ms.
Learnt after first starting during external area error from several in the maloperation analysis of cases of decompression, voltage transformer secondary is equal
For three-phase pressure loss, and to be analyzed from its recorder data, secondary remaining stray voltage is very low, and two sub-value maximums are usually no more than 2V,
The generation moment of decompression general lagging current amount mutation more than Startup time 20ms simultaneously, therefore draw above-mentioned criterion.
1. item criterion：When generation threephase potential transformer breaks, voltage has certain Sudden Changing Rate, and can be compared with
Greatly, while in order to prevent from causing to judge by accident because the acquirement of voltage jump threshold value is too low in oscillatory process, so voltage jump threshold
Value is greater than voltage jump amount during minimum cycle of oscillation.The system oscillation cycle considers according to minimum 200ms, when protection installation place
Positioned at when oscillation center, voltage jump amount | U (t)-U (t-T) | just have maximum.U (t) be using 200ms as the cycle just
String waveform, T 20ms.Then
Formula is accumulated according to differenceization
By above-mentioned formula it can be seen that Lai as t=10, voltage jump amount has maximum.
After increasing floating threshold, the maximum sudden change amount of the voltage in a cycle is：
By above-mentioned formula it can be seen that Lai as t=70, voltage jump amount has maximum
Certain nargin is put in view of threshold, so threshold value takes 0.4Un, while in view of being possible to have occurred and that outside area
In the case of one phase or phase to phase fault, then occur threephase potential transformer broken string when, Sudden Changing Rate be present in the voltage for only perfecting phase, because
This criterion, which is worked as, detects that any one phase voltage Sudden Changing Rate of three-phase voltage meets condition.
2. item criterion：When voltage transformer disconnection occurs, a cycle interior energy experiences the Sudden Changing Rate of voltage, but
It is based on the reason for the full-wave fourier algorithm fourier window, voltage fourier value can't be reduced to 0, such as use half cycle algorithm, then mutual in voltage
After 10ms after sensor broken string, the voltage fourier value of calculating is 0, so the three-phase voltage fourier value calculated using half-wave algorithm.
2V is less than with three-phase voltage stable state amplitude, the condition of three-phase pressure loss occurs as voltage transformer.
3. item criterion：Due to being broken down while the condition does not consider that voltage transformer disconnection occurs, therefore
Electric current does not have any variable quantity while voltage has Sudden Changing Rate, starts definite value so adding three-phase current Sudden Changing Rate and being respectively less than
Condition, the condition be mainly used in distinguish failure caused by voltage reduce still only there occurs voltage transformer disconnection.
When three above condition is satisfied by, and continue three sampled points, it is possible to be determined as circuit after starting and occur again
Voltage transformer disconnection, as shown in Figure 2.
By the above method during distance protection starts, if differentiating that there occurs voltage transformer disconnection, locking
Distance protection, and the differentiation of voltage transformer disconnection is no longer carried out in whole start-up course, after protecting full resetting,
Continue the differentiation of voltage transformer disconnection with the voltage transformer disconnection criterion of routine again.
Currently, it is the main protection of ultra-high-tension power transmission line for leading pilot protection with the protection of optical fiber differential current, is
The important guarantee of power network safety operation.Stage distance, zero-sequenceprotection as back-up protection are ultra-high-tension power transmission line again
Necessary supplement is protected, is only improved the reliability of back-up protection, can just embody the powerful advantages of main protection, to ensureing power network
Safe operation is significant.
The above embodiments merely illustrate the technical concept and features of the present invention, and its object is to allow person skilled in the art
Scholar can understand present disclosure and implement according to this, and it is not intended to limit the scope of the present invention.It is all according to the present invention
The equivalent change or modification that Spirit Essence is made, it should all be included within the scope of the present invention.
Claims (7)
1. it is a kind of prevent power network distance protection first start after decompression malfunction method, for the distance protection equipment in power network by
After external area error starts, judge whether that threephase potential transformer secondary circuit broken string occurs, so as to prevent described distance
Protection device malfunction, it is characterised in that：This method is：Continuous n sampled point meets following criterion simultaneously：
1. the voltage jump amount of any one phase is more than the voltage jump threshold value of setting；
2. the three-phase voltage calculated using half cycle algorithm is respectively less than 2V；
3. three-phase current Sudden Changing Rate is respectively less than the startup definite value of described distance protection equipment in 20ms；
Wherein n is positive integer；
Then judge threephase potential transformer broken string occurs；
Described distance protection equipment malfunction is prevented according to result of determination.
2. it is according to claim 1 prevent power network distance protection first start after decompression malfunction method, it is characterised in that：Institute
The voltage jump threshold value stated is more than voltage jump amount during minimum cycle of oscillation.
3. it is according to claim 2 prevent power network distance protection first start after decompression malfunction method, it is characterised in that：Institute
The minimum cycle of oscillation stated is 200ms.
4. it is according to claim 2 prevent power network distance protection first start after decompression malfunction method, it is characterised in that：Institute
Voltage jump amount and floating threshold sum when the voltage jump threshold value stated is described minimum cycle of oscillation.
5. it is according to claim 2 prevent power network distance protection first start after decompression malfunction method, it is characterised in that：Institute
Voltage jump amount of the voltage jump threshold value stated in described minimum cycle of oscillation on the basis of floating threshold sum with increasing
Add and determine nargin and formed.
6. it is according to claim 5 prevent power network distance protection first start after decompression malfunction method, it is characterised in that：Institute
The voltage jump threshold value stated is 0.4Un, wherein UnFor voltage rating.
7. it is according to claim 1 prevent power network distance protection first start after decompression malfunction method, it is characterised in that：n
Value is 3.
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| CN106908649A (en) * | 2017-03-14 | 2017-06-30 | 南京保合太和电力科技有限公司 | Generator power pick-up device voltage sample system and method |
| CN109599836A (en) * | 2018-12-05 | 2019-04-09 | 上海思源弘瑞自动化有限公司 | Sudden Changing Rate determines method, apparatus, equipment and medium |
| CN115166603B (en) * | 2022-06-24 | 2023-02-28 | 北京天能继保电力科技有限公司 | Virtual connection judgment method and device for secondary circuit wiring terminal of power grid voltage transformer |
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