CN103280785B - A kind of HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault - Google Patents
A kind of HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault Download PDFInfo
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- CN103280785B CN103280785B CN201310239285.XA CN201310239285A CN103280785B CN 103280785 B CN103280785 B CN 103280785B CN 201310239285 A CN201310239285 A CN 201310239285A CN 103280785 B CN103280785 B CN 103280785B
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Abstract
The invention discloses a kind of HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault, comprise the following steps: the DC line electric current of step 1, Real-Time Monitoring converting plant side and Inverter Station side, when meeting || I
dL|-| I
dLos|| >I
settime, HVDC (High Voltage Direct Current) transmission line protection starts; Step 2, in pole control with the field bus communication of direct current protecting, add converter Trigger Angle measured value, when meeting α >k
cα
0time, start excision fault actions.The present invention does not affect by transition resistance; only need by converter Trigger Angle actual value and comparing between initial steady state minimum trigger angle; effectively can identify high resistance earthing fault, compensate for the deficiency of existing DC line protection high resistance earthing fault tripping, improve the sensitivity of protection act.
Description
Technical field
The present invention relates to technical field of HVDC transmission, particularly relate to a kind of HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault.
Background technology
The advantages such as high voltage direct current (HVDC) transmission of electricity is large with its through-put power, circuit cost is low, control performance is good, occupy more and more consequence in remote, bulk power transmission and Asynchronous Interconnection.At present, Chinese high voltage direct current transmission project quantity comes out at the top in the world.HVDC (High Voltage Direct Current) transmission line is generally as the interconnection of interconnection of large-scale power grids, and it is not only related to the stability of native system, and impact is connected the stable operation of electrical network with it.Because DC line is long, probability of malfunction is high, therefore improve the operation level of HVDC (High Voltage Direct Current) transmission line relaying protection to ensureing that the safe and reliable operation of HVDC (High Voltage Direct Current) transmission system is significant.But from the HVDC power transmission engineering put into operation both at home and abroad, HVDC transmission line relaying protection also exists theoretical incomplete, setting principle and does not have problems such as generality, and the reliability that result in HVDC transmission line protection is not high.HVDC transmission line is mainly with traveling-wave protection as quick main protection, and current differential protection is as backup protection at a slow speed.Traveling-wave protection quick action, is not subject to the impact of the factor such as load, long line distributed capacitance, but when high resistance earthing fault, easy tripping.DC line occur over the ground the high resistance earthing fault such as flashover time, if do not take measures to excise DC current source, then blow-out is very difficult, if fault sustainable existence, will have a strong impact on DC transmission system stable operation and surrounding environment safety.It is the main cause that current traveling-wave protection is difficult to detection line high resistance earthing fault that transition resistance makes voltage change ratio and variable quantity decline.Therefore, be necessary to improve the relaying configuration of HVDC transmission line, its performance is promoted, to there is excellent protective value when high resistance earthing fault.
The configuration of existing DC line protection generally comprises DC line traveling-wave protection, differential under-voltage protection, DC line longitudinal difference protection.
1, DC line traveling-wave protection
Traveling-wave protection is the main protection of DC line fault, its objective is the earth fault detected in DC line.The general principle of traveling-wave protection is: when DC line generation earth fault; circuit goes out existing ripple, direct voltage declines, and reduces after the overshoot of rectification side direct current under the effect of current controller; inverter side direct current also reduces, until be stable at setting value simultaneously.The domestic and international DC line main protection generally adopted is traveling-wave protection.Wherein, the traveling-wave protection scheme of ABB AB and SIEMENS company is extensively adopted both at home and abroad.
ABB traveling-wave protection
The general principle of the traveling-wave protection that ABB AB adopts to utilize the capable ripple of the voltage and current in DC line, and electric capacity impulse current forms pole ripple and topotype ripple respectively, realized the quick protection of DC line by the size and rate of change thereof detecting pole ripple; And according to the polarity failure judgement pole of topotype ripple.
When DC line there is shorted to earth fault, can from fault point to circuit two ends fault propagation row ripple, two ends current conversion station is by detecting pole ripple b (t)=I
d× r-U
dchange, can DC line fault be detected, form DC line protect fast.In addition, overvoltage absorption capacitor during fault on two earth electrode buses can produce an impulse current I respectively
cN1and I
cN2, utilize the change of this impulse current and the two poles of the earth direct voltage can form so-called topotype ripple G
wave, the polarity according to topotype ripple just can correctly judge fault pole.Namely
G
wave=Z
gmode(I
EL+I
CN1+I
CN2)/2-(U
D1+U
D2)/2
In formula: I
cN1and I
cN2pole 1 and pole 2 rectification side circuit direct current respectively; U
d1and U
d2be respectively rectification side circuit direct voltage on pole 1 and pole 2; I
eLfor rectification side makes somebody a mere figurehead the electric current on ground polar curve.
Siemens traveling-wave protection
Siemens traveling-wave protection is the feature sharply declined based on circuit two ends direct voltage during DC line generation earth fault; adopt voltage drop rate (du/dt) as protection starting criterion; and integration is carried out, using the size of integrated value as protection act criterion to the variable quantity of pole ripple before and after fault.
According to traveling-wave protection general principle, adopt the calculating such as voltage drop rate (du/dt) and row wave number b (t), with detection line fault, thus form the main protection of route protection.Protection criteria is: when direct voltage rate of descent is greater than set-point, carries out 10ms integration, if this integrated value is greater than set-point, send traveling-wave protection actuating signal after time delay 6ms to b (t) difference after the b (t) before fault and fault.In this delay time, if having other protection act or another pole traveling-wave protection action, then the traveling-wave protection of this pole is by locking 800ms.
The deficiency of traveling-wave protection
Initial row wave amplitude increases with transition resistance and reduces, and real protection is with Difference Calculation voltage change ratio and variable quantity, and therefore the two increases with transition resistance and reduces.It is the main cause that current traveling-wave protection is difficult to detection line high resistance earthing fault that transition resistance makes voltage change ratio and variable quantity decline.
Fault traveling wave is the high frequency transient signal of a kind of non-stationary change, is the function of time and frequency, utilizes traditional mathematical method to be difficult to comprehensively, extracts traveling wave fault information and lines of description ripple fault signature exactly.Traditional instrument transformer is difficult to accurately transmit the capable ripple transient signal of this high frequency, and the sample frequency that current traveling-wave protection adopts is not enough to flutter grasps wavefront, and when sampled value is subject to noise jamming, traveling-wave protection likely will occur malfunction.
2, differential under-voltage protection
Differential under-voltage protection is as the backup protection of traveling-wave protection, and protection is only effective in converting plant.It detects direct voltage and direct current, and the protection act condition having differential different with under voltage two kinds, be combined with each other the correctness that can improve protection act.Differential part is made up of a differential circuit, when DC line generation earth fault, direct voltage with higher rate reduction to a lower value, the quick acting of differential detection part; For making differential detection more perfect, direct current under voltage to be detected, higher differential setting value and lower under voltage level simultaneously, then consider suitable time-delay can prevent transient voltage under false protection.For distinguishing outside district and troubles inside the sample space, di/dt is measured while measuring du/dt, higher positive di/dt value (electric current increases in normal direction), shows that fault occurs in (namely in DC line) in district, and larger negative value then shows that fault point occurs in (containing current conversion station DC fields) outside district.
Differential under-voltage protection is subject to transition resistance impact, and differential criterion and under voltage criterion are all subject to transition resistance impact, there will be the situation of relay fail when high resistance earthing fault equally.
3, DC line longitudinal difference protection
Longitudinal difference protection, by measuring and comparing the DC line electric current at two stations, should carry out compensation of delay to measuring the time difference that electric current may occur, protection act when current differential exceedes definite value.The operating criterion starting DC line longitudinal difference protection as height is: | I
dL-I
dLos| >150A.
Communication under normal circumstances two absolute values of difference of standing erectly Flow Line current absolute value be greater than definite value, then protect startup, action after protection time delay 500ms.
DC line longitudinal difference protection is because of the impact of Given current controller, and its vertical difference definite value is less, and simultaneously by the impact of line traffic transmission delay, its time delay is larger.In addition by the impact of capacitance current in unsymmetrical current and fault transient process, make longitudinal difference protection sensitivity not high, current longitudinal difference protection can only as backup protection at a slow speed.
In sum, there is weak link in the protection traveling-wave protection of existing HVDC (High Voltage Direct Current) transmission line and longitudinal difference protection configuration, and during high resistance earthing fault, DC line protection exists and action in time can not excise the situation of fault.
Summary of the invention
For above deficiency; the invention provides a kind of HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault; it considers the impact that control system responds fast when line fault; direct current system characteristic feature amount is introduced DC line protection; construct DC line protection new principle identification high resistance earthing fault in the time domain, make up the deficiency that main protection (traveling-wave protection) tripping, backup protection (line differential protection) speed are excessively slow.
For realizing above object, the technical scheme that the present invention takes is:
A HVDC (High Voltage Direct Current) transmission line guard method for identifiable design high resistance earthing fault, comprises the following steps:
The DC line electric current of step 1, Real-Time Monitoring converting plant side and Inverter Station side, when meeting formula (1), HVDC (High Voltage Direct Current) transmission line protection starts;
||I
dL|-|I
dLos||>I
set（1）
In formula (1), I
dLfor the DC line electric current of converting plant side, I
dLosfor the DC line electric current of Inverter Station side, I
setfor set point, I
set=max{1.6I
co, 0.05I
n, wherein, I
cofor converting plant side senser and the Inverter Station side senser error amount when rated current, I
nfor rated current;
Step 2, in pole control with the field bus communication of direct current protecting, adding converter Trigger Angle measured value, when meeting formula (2), starting excision fault actions;
α>k
cα
0（2）
In formula (2), α is Trigger Angle measured value, k
cfor safety factor, α
0for definite value, it is the size of the converter Trigger Angle of maximum high resistance ground value.
The condition meeting formula (1) in step 1 is 30-40ms to the delay time starting the action of DC line longitudinal difference protection.
The condition meeting formula (2) in step 2 is 3-10ms to starting the delay time excising fault actions.
Safety factor k in step 2
cscope be: 1.05≤k
c≤ 1.1.
In step 2, maximum high resistance ground value is 1000 Europe.
Herein on the basis analyzing existing DC line protection; propose a kind of HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault; the method adopts two ends electric parameters to carry out differing from stream startup in time domain, when during initial steady state, Trigger Angle is greater than definite value, and protection act.
Compared with prior art, tool has the following advantages in the present invention:
(1) principle does not affect by transition resistance; only need by comparing between converter Trigger Angle actual value (i.e. measured value) with initial steady state minimum trigger angle (i.e. the converter Trigger Angle of maximum high resistance ground value); effectively can identify high resistance earthing fault; compensate for the deficiency of existing DC line protection high resistance earthing fault tripping, improve the sensitivity of protection act.
(2) the protection act time limit is short, needing about 40ms altogether, meeting protection act rapidity requirement from breaking down to protection act.
(3) introduce the characteristic feature amount-Trigger Angle of direct current system, for the design concept of direct current protecting provides reference, the impact of control system during DC line protection principle design, can be taken into full account, new direct current protecting can be configured for specific fault feature.
(4) be easy in Practical Project realize, do not need additional hardware equipment and cable, only need add Trigger Angle measured value in pole control with the field bus communication of direct current protecting, not affect the stable operation of control system.
(5) this protection is as the nearly backup protection of DC line main protection (traveling-wave protection), optimizes the configured in one piece of DC line protection.
Accompanying drawing explanation
Fig. 1 is the structural representation of 12 pulse conversion device converting plants;
Fig. 2 is the flow chart of the HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, content of the present invention is described in further details.
One, the DC line protection principle of converter Trigger Angle is utilized
After DC line breaks down, control system gets involved immediately and works, converter phase shift, adjustment Trigger Angle.In initial transient processes, rectification side direct voltage declines, and direct current rises; Inverter side direct voltage and direct current all decline.If generation high resistance earthing fault, the stable state control system Trigger Angle escaping initial transient processes will be greater than certain value, and this Trigger Angle is greater than Trigger Angle when normally running.
The DC line protection principle of converter Trigger Angle that utilizes that the present invention proposes is: DC line two station is poor stream conduct protection entry condition longitudinally; Using converter Trigger Angle during high resistant (maximum) earth fault during initial steady state as protection act threshold, actual measurement Trigger Angle is greater than this definite value, then protection act.
Protected mode of the present invention all can arrange Protection criteria in converting plant and Inverter Station, and its principle is consistent, and introduce configuration principle and the computational methods of this protection here for converting plant, Inverter Station computational methods can be analogized.
During high resistance earthing fault, Trigger Angle calculates
The 12 pulse conversion device converting plants for shown in Fig. 1:
U
f=I
1R （1-2）
U
i=U
f+I
dr
0l （1-3）
I
d=I
1+I
2（1-4）
Wherein E is converter transformer valve-side non-loaded line voltage effective value, X
rithe every phase commutating reactance of converting plant, r
0for circuit resistance per unit length value, l is the distance of fault point to converting plant, I
dfor rated direct current, R is transition resistance, I
1for flowing through the electric current of transition resistance, can be taken as 0.1I in Given current controller pattern
d.Comprehensive above formula calculates:
Along with l, R increase in formula (2-1), α reduces.R is transition resistance value, transition resistance is not more than 1000 Europe, in actual high-voltage direct current system, when R get 1000 Europe, l is taken as total track length, other parameters are HVDC Equipments intrinsic parameter time, substitute into formula (2-1) and initial steady state minimum trigger angle α after line fault can be calculated
0, initial steady state minimum trigger angle α after this line fault
0the size of converter Trigger Angle when that is to say maximum high resistance ground value (namely maximum transition resistance value).
Two, the method for the DC line protection of converter Trigger Angle is utilized
Please refer to Fig. 2, utilize the method for the DC line protection of converter Trigger Angle, comprise the following steps:
The DC line electric current of S1, Real-Time Monitoring converting plant side and Inverter Station side, when meeting formula (3-1), the preferred 35ms of time delay 30-40ms(), this protection starts, otherwise, continue the DC line electric current monitoring converting plant side and Inverter Station side.
||I
dL|-|I
dLos||>I
set（3-1）
The entry condition that formula (3-1) is protected for this HVDC (High Voltage Direct Current) transmission line, the entrance that namely this guard method starts.Wherein I
dLfor the DC line electric current of converting plant side, I
dLosfor the DC line electric current of Inverter Station side, I
setfor set point, I
set=max{1.6I
co, 0.05I
n, wherein, I
cofor converting plant side senser and the Inverter Station side senser error amount when rated current, I
nfor rated current.
S2, in pole control with the field bus communication of direct current protecting, add converter Trigger Angle measured value, when meeting formula (4-1), the preferred 5ms of time delay 3-10ms(), start excision fault actions, the method for failure removal is prior art, is not repeating here.
α>k
cα
0（4-1）
Wherein k
cfor safety factor, get 1.05-1.1, α
0for converter Trigger Angle during maximum high resistance ground value (adopting formula (2-1) to calculate), be generally 50-55 degree.
Above-listed detailed description is illustrating for possible embodiments of the present invention, and this embodiment is also not used to limit the scope of the invention, and the equivalence that all the present invention of disengaging do is implemented or changed, and all should be contained in the protection range of this case.
Claims (3)
1. a HVDC (High Voltage Direct Current) transmission line guard method for identifiable design high resistance earthing fault, is characterized in that, comprise the following steps:
The DC line electric current of step 1, Real-Time Monitoring converting plant side and Inverter Station side, when meeting formula (1), HVDC (High Voltage Direct Current) transmission line protection starts;
||I
dL|-|I
dLos||>I
set(1)
In formula (1), I
dLfor the DC line electric current of converting plant side, I
dLosfor the DC line electric current of Inverter Station side, I
setfor set point, I
set=max{1.6I
co, 0.05I
n, wherein, I
cofor converting plant side senser and the Inverter Station side senser error amount when rated current, I
nfor rated current;
Step 2, in pole control with the field bus communication of direct current protecting, adding converter Trigger Angle measured value, when meeting formula (2), starting excision fault actions;
α>k
cα
0(2)
In formula (2), α is Trigger Angle measured value, k
cfor safety factor, α
0for definite value, it is the size of the converter Trigger Angle of maximum high resistance ground value;
The condition meeting formula (1) in step 1 is 30-40ms to the delay time starting HVDC (High Voltage Direct Current) transmission line protection act;
The condition meeting formula (2) in step 2 is 3-10ms to starting the delay time excising fault actions;
Described HVDC (High Voltage Direct Current) transmission line protection is as the nearly backup protection of DC line main protection.
2. the HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault according to claim 1, is characterized in that, safety factor k in step 2
cscope be: 1.05≤k
c≤ 1.1.
3. the HVDC (High Voltage Direct Current) transmission line guard method of identifiable design high resistance earthing fault according to claim 1, is characterized in that, in step 2, maximum high resistance ground value is 1000 Europe.
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| CN103872657A (en) * | 2014-03-19 | 2014-06-18 | 许继集团有限公司 | Metal loop wire longitudinal differential protection method in parallel-connection ice melting mode |
| CN103972873A (en) * | 2014-05-14 | 2014-08-06 | 国网上海市电力公司 | Method for protecting high-voltage DC three-pole power transmission line |
| CN104538941B (en) * | 2014-12-16 | 2018-01-09 | 国家电网公司 | A kind of HVDC transmission line traveling-wave protection fixed value adjusting method |
| CN105207181B (en) * | 2015-09-21 | 2018-08-03 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | A kind of adaptive method of undervoltage protection of hvdc transmission line |
| CN107104416B (en) * | 2016-11-28 | 2018-12-28 | 华北电力大学（保定） | The DC line relay protecting method of direct-flow distribution system is pressed during a kind of multiterminal are flexible |
| CN109975656B (en) * | 2019-03-06 | 2021-09-07 | 河南理工大学 | High-resistance grounding fault detection method based on flexible direct-current power distribution network |
| CN110137924A (en) * | 2019-06-06 | 2019-08-16 | 北京四方继保自动化股份有限公司 | The differential guard method of transmission line of electricity and device |
| CN110429571B (en) * | 2019-07-04 | 2022-04-15 | 中国电力科学研究院有限公司 | Selectable-pole direct-current transmission line protection method and system |
| CN110837023B (en) * | 2019-09-30 | 2020-11-24 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Method for judging voltage measurement abnormity of extra-high voltage direct current rectifying side |
| CN114498579B (en) * | 2021-12-29 | 2024-04-09 | 西安理工大学 | High-voltage transmission line protection starting element based on transition resistance and change rate thereof |
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