CN103346542B - Based on the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods of distributed constant - Google Patents

Based on the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods of distributed constant Download PDF

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CN103346542B
CN103346542B CN201310253138.8A CN201310253138A CN103346542B CN 103346542 B CN103346542 B CN 103346542B CN 201310253138 A CN201310253138 A CN 201310253138A CN 103346542 B CN103346542 B CN 103346542B
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fault
rfm
hvdc
transmission line
high resistance
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CN103346542A (en
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翟永昌
张怿宁
李永丽
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Maintenance and Test Center of Extra High Voltage Power Transmission Co
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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Abstract

The invention discloses the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods based on distributed constant, comprise the following steps: the DC line electric current of step 1, Real-Time Monitoring converting plant side and Inverter Station side, if met within the continuous 3ms time || I r|-| I i|| >I settime, then judge have fault point to exist in this HVDC (High Voltage Direct Current) transmission line, perform step 2; Step 2, respectively from converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFmif, U rFm>=0.1I dr, be then judged as high resistance earthing fault in district, time delay t 1protection exit; If U rFm<0.1I dr, be then judged as metallicity fault in district, time delay t 2protection exit.The size of initial steady state voltage when fault point residual voltage and high resistance earthing fault when the present invention is by comparing hvdc transmission line earth fault; judge whether high resistance earthing fault occurs; thus starting protection outlet; it does not affect by transition resistance; compensate for the deficiency of existing DC line protection high resistance earthing fault tripping, improve the sensitivity of protection act.

Description

Based on the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods of distributed constant
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 high resistance earthing fault recognition methods based on distributed constant.
Background technology
HVDC (High Voltage Direct Current) 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 power supply, 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.
Traveling-wave protection both at home and abroad at present comprises ABB traveling-wave protection and Siemens traveling-wave protection.Its principle is as follows:
1, ABB traveling-wave protection
The general principle of ABB traveling-wave protection 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.
2, 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.
3, the deficiency of existing 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.
Summary of the invention
For above deficiency; the invention provides a kind of HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods based on distributed constant; the size of initial steady state voltage when fault point residual voltage and high resistance earthing fault when it is by comparing hvdc transmission line earth fault; judge whether high resistance earthing fault occurs; thus starting protection outlet, locking high-voltage direct current.
For realizing above object, the technical scheme that the present invention takes is:
Based on the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods of distributed constant, comprise the following steps:
The DC line electric current of step 1, Real-Time Monitoring converting plant side and Inverter Station side, if when meeting formula (1) within the continuous 3ms time, then judges have fault point to exist in this HVDC (High Voltage Direct Current) transmission line, performs step 2;
||I R|-|I I||>I set（1）
Wherein, I rfor the DC line electric current of converting plant side, I ifor the DC line electric current of Inverter Station side, I setfor set point, I set=max{1.6I co, 0.05I n, I cofor converting plant side senser and the Inverter Station side senser error amount when rated current, I nfor DC transmission system rated current;
Step 2, respectively from converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFm, the two meets formula (2):
|U RFm-U IFm|≤10 -3kV （2）
If U rFm>=0.1I dr, be then judged as high resistance earthing fault in district, time delay t 1protection exit;
If U rFm<0.1I dr, be then judged as metallicity fault in district, time delay t 2protection exit;
Wherein: I dfor the DC line electric current of converting plant side before fault, R is 300 Ω, 0.1I dinitial steady state voltage when R is high resistance earthing fault.
Described converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFmmethod be:
U RFm = U R ch ( rm ) - Z C I R sh ( rm ) U IFm = U I ch ( r ( l - m ) ) - Z C I I sh ( r ( l - m ) ) - - - ( 3 )
In formula (3), l is the overall length of this HVDC (High Voltage Direct Current) transmission line, and m is the length of fault point distance converting plant side, Z c, r is respectively the wave impedance of this HVDC (High Voltage Direct Current) transmission line, the resistance of unit length, U rfor the AC line voltage of converting plant side, U ifor the AC line voltage of Inverter Station side.
Also comprise before step 2:
Calculate the position of fault point;
The computational methods of the position of described fault point are:
Order wherein, n is positive integer, to m from n=1 successively value, until meet formula (2); Between two ± select+or-method be: if time, U iFm-U rFm>10 -3kV, then make continue to compare U rFmand U iFmsize, otherwise, if time, U rFm-U iFm>10 -3kV, then make continue to compare U rFmand U iFmsize, wherein a is positive integer and 1≤a<n.
Described t 1for 3ms.
Described t 2for 2ms.
Compared with prior art, tool has the following advantages in the present invention:
(1) the present invention does not affect by transition resistance, effectively can identify high resistance earthing fault, compensate for the deficiency of existing DC line protection high resistance earthing fault tripping, improves the sensitivity of protection act.
(2) the protection act time limit is short, needing about 35ms altogether, meeting protection act rapidity requirement from breaking down to protection act, compensate for the deficiency of longitudinal difference protection action delay long (about 1 second).
(3) be easy in Practical Project realize, do not need additional hardware equipment and cable, only need modify to existing HVDC (High Voltage Direct Current) transmission line protection software logic, not affect the stable operation of control system.
(4) 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 flow chart of the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods that the present invention is based on distributed constant;
Fig. 2 is the structural representation of HVDC (High Voltage Direct Current) transmission line;
Fig. 3 is after HVDC (High Voltage Direct Current) transmission line breaks down, the voltage change curve figure along the line of converting plant side and Inverter Station side to fault point.
Embodiment
Below in conjunction with the drawings and specific embodiments, content of the present invention is described in further details.
Embodiment:
Please refer to shown in Fig. 1, and the illustraton of model of HVDC (High Voltage Direct Current) transmission line shown in composition graphs 2.A HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods for distributed constant, comprises the following steps:
The DC line electric current of S01, Real-Time Monitoring converting plant side and Inverter Station side, if when meeting formula (1) within the continuous 3ms time, then judge have fault point to exist in this HVDC (High Voltage Direct Current) transmission line, perform S02, otherwise, continue the DC line electric current monitoring converting plant side and Inverter Station side;
||I R|-|I I||>I set（1）
The entrance that formula (1) is protected HVDC (High Voltage Direct Current) transmission line for the present invention.Wherein, I rfor the DC line electric current of converting plant side, I ifor the DC line electric current of Inverter Station side, I setfor set point, I set=max{1.6I co, 0.05I n, I cofor converting plant side senser and the Inverter Station side senser error amount when rated current, I nfor DC transmission system rated current.
The position (namely calculating the length of fault point distance converting plant side) of S02, calculating fault point, then respectively from converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFm, the two meets formula (2):
|U RFm-U IFm|≤10 -3kV （2）
In formula (2) 10 -3for error coefficient.
If U rFm>=0.1I dr, be then judged as high resistance earthing fault in district, time delay t 1(preferred 3ms) protection exit;
If U rFm<0.1I dr, be then judged as metallicity fault in district, time delay t 2(preferred 2ms) protection exit;
Wherein: I dfor the DC line electric current of converting plant side before fault, R is 300 Ω, 0.1I dinitial steady state voltage (fixed value) when R is high resistance earthing fault; in district, high resistance earthing fault is identical with the protection exit mode of metallicity fault in district; all adopt locking HVDC (High Voltage Direct Current) transmission line, and all start high voltage direct current transmission line fault restarting function after protection exit.
Converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFmmethod be:
U RFm = U R ch ( rm ) - Z C I R sh ( rm ) U IFm = U I ( r ( l - m ) ) - Z C I I sh ( r ( l - m ) ) - - - ( 3 )
In formula (3), l is the overall length of this HVDC (High Voltage Direct Current) transmission line, and m is the length of fault point distance converting plant side, Z c, r is respectively the wave impedance of this HVDC (High Voltage Direct Current) transmission line, the resistance of unit length, U rfor the AC line voltage of converting plant side, U ifor the AC line voltage of Inverter Station side.
The computational methods of the position of fault point can be directly make two formula in formula (3) equal, obtain the value of m.And undertaken by microprocessor due to this calculating, direct calculating then can spend the more time, can not meet the requirement of protection act rapidity, and for this reason, in the present invention, converting the value of machine language to m to calculates, and is specially, order:
m = l 2 &PlusMinus; l 2 2 &PlusMinus; . . . &PlusMinus; l 2 n - - - ( 4 )
Wherein, n is positive integer, to the m in general term formula (4) from n=1 successively value, and substitutes in formula (3) until meet formula (2)." ± " in general term formula (4) between two selects one and selects positive sign or negative sign, selects the principle of positive sign or negative sign to be: if time, U iFm-U rFm>10 -3kV, then make continue to compare U rFmand U iFmsize, otherwise, if time, U rFm-U iFm>10 -3kV, then make continue to compare U rFmand U iFmsize, wherein a is positive integer and 1≤a<n.
Such as, first get will in substitution formula (3), if U rFm-U iFm>10 -3kV, then get then will again substitute in formula (3), if U iFm-U rFm>10 -3kV, then get the like.
Judge that the theoretical foundation whether HVDC (High Voltage Direct Current) transmission line high resistance earthing fault occurs is: after HVDC (High Voltage Direct Current) transmission line breaks down, from converting plant side to fault point and all on a declining curve from Inverter Station side to fault point voltage along the line, (transverse axis is fault point distance to voltage f (x) distribution schematic diagram ideally along the line as shown in Figure 3, the longitudinal axis is voltage f (x) along the line, and fault point is x f).And from HVDC (High Voltage Direct Current) transmission line high resistance earthing fault just instantaneously to high resistance ground initial steady state process, along with the effect of DC control system, the voltage of fault point is on a declining curve, until drop to the residual voltage of initial steady state.
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., based on the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods of distributed constant, it 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, if when meeting formula (1) within the continuous 3ms time, then judges have fault point to exist in this HVDC (High Voltage Direct Current) transmission line, performs step 2;
||I R|-|I I||>I set(1)
Wherein, I rfor the DC line electric current of converting plant side, I ifor the DC line electric current of Inverter Station side, I setfor set point, I set=max{1.6I co, 0.05I n, I cofor converting plant side senser and the Inverter Station side senser error amount when rated current, I nfor DC transmission system rated current;
Step 2, respectively from converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFm, until the two meets formula (2):
|U RFm-U IFm|≤10 -3kV (2)
If U rFm>=0.1I dr, be then judged as high resistance earthing fault in district, time delay t 1protection exit;
If U rFm<0.1I dr, be then judged as metallicity fault in district, time delay t 2protection exit;
Wherein: I dfor the DC line electric current of converting plant side before fault, R is 300 Ω, 0.1I dinitial steady state voltage when R is high resistance earthing fault;
Described converting plant side calculating fault point residual voltage U rFmwith calculating fault point, Inverter Station side residual voltage U iFmmethod be:
U RFm = U R ch ( rm ) - Z C I R sh ( rm ) U IFm = U I ch ( r ( l - m ) ) - Z C I I sh ( r ( l - m ) ) - - - ( 3 )
In formula (3), l is the overall length of this HVDC (High Voltage Direct Current) transmission line, and m is the length of fault point distance converting plant side, Z c, r is respectively the wave impedance of this HVDC (High Voltage Direct Current) transmission line, the resistance of unit length, U rfor the AC line voltage of converting plant side, U ifor the AC line voltage of Inverter Station side;
Also comprise before step 2:
Calculate the position of fault point;
The computational methods of the position of described fault point are:
Order wherein, n is positive integer, to m from n=1 successively value, until meet formula (2); Between two ± select+or-method be: if time,
U iFm-U rFm>10 -3kV, then make continue to compare U rFmand U iFmsize, otherwise, if time, U rFm-U iFm>10 -3kV, then make continue to compare U rFmand U iFmsize, wherein a is positive integer and 1≤a<n.
2. the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods based on distributed constant according to claim 1, is characterized in that, described t 1for 3ms.
3. the HVDC (High Voltage Direct Current) transmission line high resistance earthing fault recognition methods based on distributed constant according to claim 1, is characterized in that, described t 2for 2ms.
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