CN104269890B - The control method of extra-high voltage direct-current layer-specific access mode and system - Google Patents
The control method of extra-high voltage direct-current layer-specific access mode and system Download PDFInfo
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Abstract
The control method of extra-high voltage direct-current layer-specific access mode and a system, described method comprises step: A, collection DC current signal and each converter d. c. voltage signal of inverter side; B, according to DC current signal and each converter d. c. voltage signal of inverter side, the converter position that judging distance fault point is nearest; C, when fault occurs in rectification side, do not control the current limiting low-voltage link of rectification side and inverter; D, when fault occurs in inverter side, determine whether the current limiting low-voltage link needing locking nearest from fault point according to abort situation and duration; The current limiting low-voltage link that E, if desired locking are nearest from fault point, then the current limiting low-voltage link of the current limiting low-voltage link nearest from fault point and rectification side described in locking simultaneously.By adopting the detection method of electric energy quality monitoring data of the present invention, can take into full account the AC conditions of the whole AC system of inverter side, the current limiting low-voltage link that the AC system avoiding AC conditions weak connects does not start, and thereby enhances the stability of system.
Description
Technical field
The present invention relates to power system device field, particularly a kind of control method of extra-high voltage direct-current layer-specific access mode and system.
Background technology
Along with the extensive use of extra-high voltage alternating current-direct current technology, multi-infeed HVDC is concentrated and fallen into receiving end load center will be the major issue that following power network development faces.For effectively solving the problem of multi-infeed HVDC system from electric network composition, the mode of extra-high voltage direct-current layer-specific access AC network can be used.
A kind of extra-high voltage direct-current system inverter side layer-specific access mode realizes the instantiation of the network architecture of different electric pressure AC system as shown in Figure 1, namely ± 1100kV extra-high voltage direct-current system receiving end layer-specific access 500kV/1000kV AC system.This system is different from traditional two-terminal direct current transmission system, and under this mode of connection, DC inversion side is connected to multiple AC system, and therefore this is actually a kind of connection type of multiterminal element of connecting.
On the other hand, current limiting low-voltage link (VDCOL, voltagedependentcurrentlimiter) is widely used a kind of current-limiting apparatus in existing Traditional DC engineering.When system suffers large disturbances, direct voltage or change of current busbar voltage will decline rapidly, now VDCOL can reduce direct current instruction to reduce direct current power, current conversion station can be reduced between age at failure like this to the reactive requirement of AC system, help to recover alternating voltage, reduce the probability of commutation failure.The startup of VDCOL can detect and exchange commutation voltage or direct voltage, during due to DC Line Fault, AC system is idle, and surplus will cause commutation voltage to raise, and not have what effect when therefore alternating voltage is enabled in DC Line Fault, therefore under normal conditions, VDCOL starts according to direct voltage.The setting of VDCOL initiation value, according to the difference of connected AC system AC conditions also difference to some extent, in general, short circuit ratio (SCR, shortcircuitratio) little AC system is because it is idle and voltage support ability is more weak, and the VDCOL initiation value be thus connected with this AC system is higher; The large AC system of short circuit ratio is then because it is idle and voltage support ability is comparatively strong, and the VDCOL initiation value be therefore connected with this AC system is lower.
Existing two ends DC engineering, general rectification side and inverter side are all equiped with VDCOL, and the starting resistor of these VDCOL is general to be determined by the monopolar D. C voltage of rectification side and inverter side respectively.Correspondingly, the current-order that direct current instruction is exported by the current limiting low-voltage device of rectification side and inverter side is got minimum value and is obtained later.It is exactly more than the introduction that the effect of VDCOL and initiation value are adjusted.
Because the extra-high voltage direct-current system inverter side under layer-specific access mode is connected with the AC system of multiple different AC conditions, thus under this network topology structure, if will there is following problem according to monopolar D. C voltage starting VDCOL in inverter side: the AC conditions that 1) can not take into full account each AC system of inverter side, as previously mentioned, the initiation value of the VDCOL that the AC system that AC conditions is weak that is short circuit ratio is little connects is higher, therefore when the AC system commutation voltage likely causing a certain AC conditions more weak is very low, VDCOL does not start, thus affect the voltage stabilization of this AC system, 2) when a certain AC system generation catastrophe failure, cause its when connecting converter blocking, owing to having lacked corresponding direct voltage, rectification side VDCOL has been in limited current state all the time, the AC system that inverter side is not broken down connect the power of converter can not quick-recovery soon.
Summary of the invention
Given this, the object of the invention is to the AC conditions taking into full account the whole AC system of inverter side, the VDCOL that the AC system avoiding AC conditions weak connects does not start, because this enhancing the stability of system; And object is when inverter side AC system generation catastrophe failure, ensure inverter side non-faulting AC system connect the fast quick-recovery of the power of converter.
To achieve these goals, the present invention proposes a kind of control method and system of extra-high voltage direct-current layer-specific access mode, technical scheme is specific as follows:
A control method for extra-high voltage direct-current layer-specific access mode, comprises step: A gathers DC current signal and each converter d. c. voltage signal of inverter side; B according to DC current signal and each converter d. c. voltage signal of inverter side, the converter position that judging distance fault point is nearest; C occurs in rectification side when fault, does not control the VDCOL of rectification side and inverter; D occurs in inverter side when fault, determines whether the VDCOL needing locking nearest from fault point according to abort situation and duration; The E VDCOL that if desired locking is nearest from fault point, the then VDCOL of the VDCOL nearest from fault point and rectification side described in locking simultaneously.
Wherein, described according to each converter d. c. voltage signal of direct current inverter side, the step of the converter position that judging distance fault point is nearest comprises: if be less than predetermined current threshold after B1 direct current deducts when system is normally run rated direct current, be then judged as that rectification side breaks down or system failure; If B2 direct current is greater than predetermined current threshold after deducting rated direct current when system is normally run, then rated direct voltage when more each converter direct voltage and this converter normally run; If the rated direct voltage that B3 one converter direct voltage is less than when this converter normally runs exceedes predetermined voltage threshold, then the VDCOL that described converter connects is the VDCOL nearest from fault point.
Especially, described predetermined current threshold is 0.1pu-0.2pu, and described predetermined voltage threshold is 0.7pu-0.8pu.
In addition, the step of described collection DC current signal and inverter side each converter d. c. voltage signal comprises: by described DC current signal and each converter d. c. voltage signal of inverter side through the process of single order time delay process.
Especially, the expression formula of described single order time delay process is
Wherein K represents single order time delay process, and the measured value of each for inverter side converter d. c. voltage signal and DC current signal is converted to nondimensional perunit value by gain G, and T is time constant.
And described time constant T, being 0.02 for each converter d. c. voltage signal of described inverter side, is 0.012 for described DC current signal.
In addition, described DC current signal and each converter d. c. voltage signal of inverter side after the process of single order time delay process, through the foundation of analog-to-digital conversion as nearest converter position, the judging distance fault point of step B.
The control method of extra-high voltage direct-current layer-specific access mode of the present invention, wherein after locking VDCOL step, comprises further: F, the current-order exported by each VDCOL form the input of current control amplifier CCA after getting annelet.
Wherein determine whether to need the step of the locking VDCOL nearest from fault point to comprise according to abort situation and duration: if nearest converter two ends, fault point direct voltage is after exceeding the scheduled time; do not return within the scope of the predetermined voltage threshold of rated direct voltage when described converter normally runs; then be defined as the VDCOL needing locking nearest from fault point, the wherein said scheduled time is relaying protection operate time and device delay time sum.
In addition, the step of nearest from fault point described in locking VDCOL and the VDCOL of rectification side comprises: the current-order of described VDCOL is switched to the value larger than direct current design maximum value.
The present invention also discloses a kind of control system of extra-high voltage direct-current layer-specific access mode, comprise the VDCOL of rectification side and inverter side, the VDCOL of described inverter side is connected with the converter of inverter side, start according to the direct voltage of connected converter, described control system also comprises: signal gathering unit, and described signal gathering unit gathers DC current signal and each converter d. c. voltage signal of inverter side; Fault end judging unit, described fault end judging unit is according to DC current signal and each converter d. c. voltage signal of inverter side, the converter position that judging distance fault point is nearest, and when fault occurs in inverter side, described fault end judging unit determines whether the VDCOL needing locking nearest from fault point according to abort situation and duration, latching logic unit, the VDCOL of the VDCOL nearest from fault point and rectification side described in the locking of described latching logic unit.
By adopting control method and the system of extra-high voltage direct-current layer-specific access mode of the present invention, the AC conditions of the whole AC system of inverter side can be taken into full account, the VDCOL that the AC system avoiding AC conditions weak connects does not start, because this enhancing the stability of system; When permanent fault can also be avoided in addition to occur, the VDCOL that fault-free converter connects is in limited current state for a long time and causes direct current power power not recover, and therefore makes the fast quick-recovery of system.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of extra-high voltage direct-current layer-specific access mode.
Fig. 2 is the schematic diagram of the control system of extra-high voltage direct-current layer-specific access mode.
Fig. 3 be different AC system when breaking down direct current and converter direct voltage compare schematic diagram.
Fig. 4 is the method flow schematic diagram of failure judgement end.
Fig. 5 is the logical schematic producing block signal.
When Fig. 6 is fault, each converter of inverter side connects VDCOL output current instruction curve.
Fig. 7 be by monopolar D. C voltage adjust with by converter direct voltage setting current instruction comparison diagram.
Fig. 8 adjusts and electric parameters comparison diagram of adjusting by converter direct voltage by monopolar D. C voltage.
Fig. 9 be add use embodiment of the present invention control system before and after converter blocking time electric current and power ratio comparatively schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, the present invention is elaborated.
Be described in the extra-high voltage direct-current layer-specific access mode in Fig. 1 in embodiments of the present invention, such as, under working in specific electric current, electric pressure, and inverter side only includes 500KV and 1000KV AC system, but those skilled in the art should understand that, these electric pressures, topological structure are only examples, utilize method of the present invention can also be applied to more complicated system, more electric pressure.
The example embodiment that following discloses are detailed.But concrete structure disclosed herein and function detail are only the objects for describing example embodiment.
But should be appreciated that, the present invention is not limited to disclosed concrete example embodiment, but covers all modifications, equivalent and the alternative that fall within the scope of the disclosure.In the description to whole accompanying drawing, identical Reference numeral represents identical element.
Should be appreciated that, term "and/or" as used in this comprises one or morely relevant lists any of item and all combinations simultaneously.Should be appreciated that in addition, when parts or unit are called as " connection " or " coupling " to another parts or unit, it can be directly connected or coupled to miscellaneous part or unit, or also can there is intermediate member or unit.In addition, other words being used for describing relation between parts or unit should be understood according to identical mode (such as, " between " to " directly ", " adjacent " to " direct neighbor " etc.).
Figure 1 shows that the present invention for the schematic diagram of extra-high voltage direct-current layer-specific access mode.Namely ± 1100kV extra-high voltage direct-current system receiving end layer-specific access 500kV/1000kV AC system, different from traditional two-terminal direct current transmission system, under this mode of connection, DC inversion side is connected to multiple AC system, and this is actually a kind of connection type of multiterminal element of connecting.
The control method technical scheme of extra-high voltage direct-current layer-specific access mode of the present invention is specific as follows:
A, collection DC current signal and each converter d. c. voltage signal of inverter side; B, according to DC current signal and each converter d. c. voltage signal of inverter side, the converter position that judging distance fault point is nearest; C, when fault occurs in rectification side, do not control the VDCOL of rectification side and inverter; D, when fault occurs in inverter side, determine whether the VDCOL needing locking nearest from fault point according to abort situation and duration; The VDCOL that E, if desired locking are nearest from fault point, the then VDCOL of the VDCOL nearest from fault point and rectification side described in locking simultaneously.
Correspondingly, for the control system of extra-high voltage direct-current layer-specific access mode schematic diagram as shown in Figure 2.
The initiation value of VDCOL is adjusted according to AC system reactive power support ability; Under extra-high voltage direct-current layer-specific access mode, due to inverter side connect multiple AC system reactive power support ability be discrepant, generally 1000kV AC system short circuit ratio is greater than 500kV AC system short circuit ratio, so 1000kV AC system has stronger idle and voltage support ability compared with 500kV AC system.Therefore the VDCOL initiation value of each converter is also different.And each converter is cascade, if because fault causes direct current to rise, then likely each converter VDCOL all starts, the current-order that now different converter VDCOL exports may be different, therefore needs to get little of the uniqueness that must ensure each moment direct current system current-order to the instruction of each converter device VDCOL output current.
Therefore, the control system of described extra-high voltage direct-current layer-specific access mode comprises the VDCOL of rectification side and inverter side, and the VDCOL of described inverter side is connected with the converter of inverter side, starts according to the direct voltage of connected converter.Described control system also comprises: signal gathering unit (not shown), and described signal gathering unit gathers DC current signal Id and each converter d. c. voltage signal of inverter side UdI and UdII; Fault end judging unit, described fault end judging unit according to DC current signal Id and each converter d. c. voltage signal of inverter side UdI and UdII, the converter position that judging distance fault point is nearest.When fault occurs in inverter side, described fault end judging unit determines whether the VDCOL needing locking nearest from fault point according to abort situation and duration, that is sends block signal.Latching logic unit, the VDCOL of the VDCOL that described latching logic unit is nearest from fault point according to block signal locking and rectification side.
Be described below in conjunction with the control method of extra-high voltage direct-current layer-specific access mode of the present invention and the embodiment of control system.
In steps A, when gathering DC current signal and each converter d. c. voltage signal of inverter side, need to carry out numerical value process and the disposal of gentle filter to signal, concrete way is that signal is formed the respective electric signal entering subsequent control through a single order time delay process.The expression formula of single order time delay process is:
Wherein K represents single order time delay process, and the measured value of voltage signal and current signal is converted to nondimensional perunit value by gain G; Time constant T is the different response speeds had according to voltage monitoring instrument and electric current electric measuring instrument, is used for the smoothing filtering process of signal.Can select time constant T be such as 0.02 for each converter d. c. voltage signal of described inverter side, be 0.012 for described DC current signal.
In order to carry out step B, below the principle coming nearest converter position, judging distance fault point according to DC current signal and inverter side each converter d. c. voltage signal is described.
Fig. 3 be different AC system when breaking down direct current and converter direct voltage compare schematic diagram.Why DC current signal and inverter side each converter d. c. voltage signal can judge the converter position that distance fault point is nearest as can be seen from this figure.
First, in direct current system, each electric parameters should meet following condition:
Wherein, Id is direct current, Ud0r is rectification side monopolar D. C floating voltage, α is rectification side Trigger Angle, Ud0iI and Ud0iII is inverter side one pole two converter floating voltages respectively, γ 1 and γ 2 is direct-flow positive pole two converters extinguish angles separately respectively, and Z contains commutating reactance and the DC line resistance of converter.The effective value of ELLk is corresponding subscript converter company's AC system commutation voltage.
Therefore, the performance of direct current when rectification side fault and inverter side fault is different.When the AC system of rectification side breaks down, the reduction of commutation voltage ELLr causes the reduction of rectification side direct-flow no load voltage Ud0k, thus causes direct current to reduce rapidly.And the AC system of inverter side is when breaking down, due to the reduction of inverter side fault end commutation voltage ELL, inverse electromotive force-Ud0i is reduced, generation one is risen and is impacted by direct current, now, due to the rising of direct current and the reduction of direct voltage, cause VDCOL to start, reduce gradually under the effect that direct current reduces at current-order.Therefore, can according to the different manifestations of electric current during fault, whether have rush of current to produce according to it, failure judgement is in rectification side or inverter side.
In addition, the converter end that also connects with guilty culprit AC system of the response of inverter side each converter direct voltage when fault is different and different.When inverter side AC system breaks down, corresponding fault end converter is due to the reduction of commutation voltage, its direct voltage will reduce rapidly, and although the direct current that non-faulting end converter is subject to the fault initial stage impacts, but because AC system does not have fault, its direct voltage reduces degree and compares much smaller compared with fault end.Therefore, the inverter side change of current end that can come residing for failure judgement according to the different manifestations of DC voltage value during fault.
Thus, in order to completing steps B, the method flow schematic diagram of failure judgement end of the present invention as shown in Figure 4.
In figure, Δ I is predetermined current threshold, and Idn is rated direct current when normally running.As Id< (Idn+ Δ I), then think that system failure or rectification side AC system there occurs fault, system does not control each VDCOL of rectification side and inverter.
And if Id> (Idn+ Δ I), be then judged as that inverter side AC system there occurs fault.Then judge which AC system concrete there occurs fault according to each converter direct voltage, even Ud< (Udn-Δ U), then be judged as this converter end connect AC system and there occurs fault, that is judge that the VDCOL be connected with this converter is the VDCOL nearest from fault point.Wherein, Δ U is predetermined voltage threshold, and Udn is the rated DC current flow valuve at this converter two ends when normally running.Now still keep the VDCOL current-order IVDCOLk nearest from fault point; If fault AC system connect converter two ends direct voltage and (consider relaying protection action and device time delay required time at Δ t; such as can select 0.2s) fail in the time to recover always; then be judged as serious permanent fault; thus send local terminal converter blocking signal, utilize this block signal by local terminal VDCOL and rectification side VDCOL locking simultaneously.
Wherein said predetermined current threshold Δ I and predetermined voltage threshold Δ U determines according to the AC conditions of system, such as, predetermined current threshold Δ I can be selected to be 0.1pu-0.2pu, and described predetermined voltage threshold Δ U is 0.7pu-0.8pu.
After step B is complete, if failure judgement occurs in direct current system rectification side, then enter step C.Because direct current system rectification side is sending end, therefore its when connecting fault in ac transmission system, because direct current directly reduces, therefore generally can not there is commutation failure; So when direct current system rectification side AC system breaks down, without the need to controlling the current limiting low-voltage link of rectification side and inverter.
On the other hand, if failure judgement occurs in inverter side.Then enter step D: when fault occurs in inverter side, determine whether the VDCOL needing locking nearest from fault point according to abort situation and duration.Illustrate with Fig. 5 below.
Fig. 5 is the logical schematic that converter blocking signal produces.For each converter of inverter side, only have when direct current appearance impact, converter two ends direct voltage decline to a great extent, and when continuing for a long time, just can cause the generation of block signal simultaneously.
The concrete logic judged: if as nearest converter two ends, fault point direct voltage is after exceeding the scheduled time; do not return within the scope of the predetermined voltage threshold of rated direct voltage when described converter normally runs; then be defined as the VDCOL needing locking nearest from fault point, the wherein said scheduled time is relaying protection operate time and device delay time sum.Especially, the scheduled time can be selected to be 0.2s.
Next step e is entered: the VDCOL that if desired locking is nearest from fault point, then the VDCOL of the VDCOL nearest from fault point and rectification side described in locking simultaneously.
Wherein, the step of nearest from fault point described in locking current limiting low-voltage link and the current limiting low-voltage link of rectification side comprises: the current-order of described VDCOL is switched to the value larger than direct current design maximum value.Such as general direct current design maximum value is 2.0pu, therefore the current-order of described VDCOL can be switched to 2.1pu.
The control method of extra-high voltage direct-current layer-specific access mode of the present invention, wherein after locking VDCOL step, comprises further: F, the current-order exported by each VDCOL form the input Iorder of current control amplifier CCA after getting annelet.Wherein, the operation principle of current control amplifier CCA is: export with VDCOL or current-order after reconciling is input, exports Trigger Angle instruction, by the adjustment of Trigger Angle, control the size of direct current in rectification side, and control the size of direct voltage in inverter side.
Below control method and the system of extra-high voltage direct-current layer-specific access mode is described by way of example.Below by way of Fig. 6-Fig. 9, the technique effect acquired by the present invention is described.
Fig. 6 be fault when occurring inverter side each converter connect the curve of VDCOL output current instruction.As can be seen from Figure 6, if not locking rectification side and inverter side fault end VDCOL, then system will keep inverter side fault end VDCOL current-order to export or rectification side VDCOL output always, cause power to be difficult to recover.
Fig. 7 adjusts (illustrating with a figure) by monopolar D. C voltage and adjusts (scheming to illustrate with b) by converter direct voltage, the current-order comparison diagram that VDCOL exports.
Wherein, a figure adjusts in VDCOL initiation value situation according to monopolar D. C voltage, converter I connect AC system valve side alternating voltage because of fault decline 20% time, the current-order that VDCOL exports.B figure be according to inverter side each converter two ends direct voltage adjust initiation value time, with each converter of inverter side in a figure same fault situation be connected the current-order that VDCOL exports.In b figure converter I with II be connected VDCOL current-order occur difference be due to converter I connect AC system and break down, and converter II connect AC system and do not break down, therefore corresponding converter VDCOL that I connects startup makes current-order reduce, and converter II does not break down due to AC system, therefore there is not obvious decline in its VDCOL.
Correspondingly, Fig. 8 adjusts (illustrating with a figure) by monopolar D. C voltage and adjusts (scheming to illustrate with b) by converter direct voltage, system electrical amount comparison diagram.
Wherein, a figure adjusts in VDCOL initiation value situation according to monopolar D. C voltage, converter I connect AC system valve side alternating voltage because of fault decline 20% time, each electric parameters curve of system; B figure be according to converter two ends direct voltage adjust VDCOL initiation value time, with each electric parameters curve of system in a figure same fault situation.As can be seen from a figure, when converter I connect AC system (short circuit is smaller) alternating voltage fall time, the direct voltage of the converter I caused thus falls and makes up by converter II (short circuit ratio is larger), therefore, whole monopolar D. C voltage does not reach the entry condition of VDCOL, but now the voltage on valve side of converter I is low to below 0.8.p.u, corresponding extinguish angle also falls to about 10 °, the voltage stability of its converter bus is a greater impact, also the as easy as rolling off a log generation causing commutation failure situation; And in b figure, because VDCOL initiation value is adjusted according to changing each stream device two ends direct voltage, therefore, when converter I connect AC system voltage on line side decline cause direct voltage drop of its two ends time, the VDCOL that converter I connects can start rapidly, direct current is reduced rapidly, and makes its extinguish angle more than 17 °, substantially reduce the risk of its commutation failure.
By Fig. 7 and Fig. 8 explanation, the control system of extra-high voltage direct-current layer-specific access mode of the present invention comprises the VDCOL of rectification side and inverter side, the VDCOL of described inverter side is connected with the converter of inverter side, start according to the direct voltage of connected converter, therefore, it is possible to take into full account the AC conditions of the whole AC system of inverter side, the VDCOL that the AC system avoiding AC conditions weak connects does not start, because this enhancing the stability of system.
Before Fig. 9 is the control method and system using extra-high voltage direct-current layer-specific access mode of the present invention (with a figure illustrate) and after (with b figure explanation) converter blocking time electric current and power ratio comparatively schematic diagram.
Wherein, a figure uses before control method of the present invention, when converter I is because of failure locking, each electric parameters curve of system, b figure be use control method of the present invention after, with under a figure same case, each electric parameters curve of system.
In a figure, there is permanent fault in the AC system that converter I connects in 5 seconds time.As can be seen from a figure, due to the VDCOL locking that converter I connects, but not to rectification side VDCOL locking, therefore the AC system (converter II connects AC system) that do not break down of inverter side connect VDCOL and be in limited current state all the time, make direct current can not return to level before fault smoothly, thus the power of converter II also fail the level before returning to fault
And in b figure, after the scheduled time of 0.2 second, the control method interpretation according to embodiment of the present invention needs locking VDCOL.Due to the VDCOL locking of change of current I, and utilize its block signal locking simultaneously rectification side VDCOL, achieve the cooperation control of each VDCOL like this.Therefore the power of converter II is made to be able to smooth recovery.
Illustrated by Fig. 9, use control method and the system of extra-high voltage direct-current layer-specific access mode of the present invention, when permanent fault can be avoided to occur, the VDCOL that fault-free converter connects is in limited current state for a long time and causes direct current power power not recover, therefore make the fast quick-recovery of system, therefore strengthen the stability of system further.
It should be noted that; above-mentioned execution mode is only the present invention's preferably embodiment; can not limiting the scope of the invention be understood as, not depart under concept thereof of the present invention, all protection scope of the present invention is belonged to modification to any minor variations that the present invention does.
Claims (11)
1. a control method for extra-high voltage direct-current layer-specific access mode, comprises the following steps:
A, collection DC current signal and each converter d. c. voltage signal of inverter side;
B, according to DC current signal and each converter d. c. voltage signal of inverter side, the converter position that judging distance fault point is nearest;
C, when fault occurs in rectification side, do not control the current limiting low-voltage link of rectification side and inverter;
D, when fault occurs in inverter side, determine whether the current limiting low-voltage link needing locking nearest from fault point according to abort situation and duration;
The current limiting low-voltage link that E, if desired locking are nearest from fault point, then the current limiting low-voltage link of the current limiting low-voltage link nearest from fault point and rectification side described in locking simultaneously.
2. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 1, is characterized in that, described according to DC current signal and each converter d. c. voltage signal of inverter side, the step of the converter position that judging distance fault point is nearest comprises:
If B1 direct current is less than predetermined current threshold after deducting rated direct current when system is normally run, be then judged as that rectification side breaks down or system failure;
If B2 direct current is greater than predetermined current threshold after deducting rated direct current when system is normally run, then rated direct voltage when more each converter direct voltage and this converter normally run;
If the rated direct voltage that B3 one converter direct voltage is less than when this converter normally runs exceedes predetermined voltage threshold, then the current limiting low-voltage link that described converter connects is the current limiting low-voltage link nearest from fault point.
3. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 2, it is characterized in that, described predetermined current threshold is 0.1pu-0.2pu, described predetermined voltage threshold is 0.7pu-0.8pu.
4. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 1, is characterized in that, the step of described collection DC current signal and each converter d. c. voltage signal of inverter side comprises:
By described DC current signal and each converter d. c. voltage signal of inverter side through the process of single order time delay process.
5. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 4, is characterized in that, the expression formula of described single order time delay process is
Wherein K represents single order time delay process, and the measured value of each for inverter side converter d. c. voltage signal and DC current signal is converted to nondimensional perunit value by gain G, and T is time constant.
6. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 5, is characterized in that, described time constant T, and being 0.02 for each converter d. c. voltage signal of described inverter side, is 0.012 for described DC current signal.
7. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 5 or 6, it is characterized in that, described DC current signal and each converter d. c. voltage signal of inverter side after the process of single order time delay process, through the basis of analog-to-digital conversion as nearest converter position, the judging distance fault point of step B.
8. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 1, wherein after locking current limiting low-voltage link step, comprises further:
F, the current-order that each current limiting low-voltage link exports is formed after getting annelet the input of current control amplifier.
9. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 1, wherein determines whether according to abort situation and duration that the step of the current limiting low-voltage link needing locking nearest from fault point comprises:
If nearest converter two ends, fault point direct voltage is after exceeding the scheduled time; do not return within the scope of the predetermined voltage threshold of rated direct voltage when described converter normally runs; then be defined as the current limiting low-voltage link needing locking nearest from fault point, the wherein said scheduled time is relaying protection operate time and device delay time sum.
10. the control method of the extra-high voltage direct-current layer-specific access mode described in claim 1, the step of wherein nearest from fault point described in locking current limiting low-voltage link and the current limiting low-voltage link of rectification side comprises:
The current-order of described current limiting low-voltage link is switched to the value larger than direct current design maximum value.
The control system of 11. 1 kinds of extra-high voltage direct-current layer-specific access modes, comprise the current limiting low-voltage link of rectification side and inverter side, the current limiting low-voltage link of described inverter side is connected with the converter of inverter side, and start according to the direct voltage of connected converter, described control system also comprises:
Signal gathering unit, described signal gathering unit gathers DC current signal and each converter d. c. voltage signal of inverter side;
Fault end judging unit, described fault end judging unit is according to DC current signal and each converter d. c. voltage signal of inverter side, the converter position that judging distance fault point is nearest, and when fault occurs in inverter side, described fault end judging unit determines whether the current limiting low-voltage link needing locking nearest from fault point according to abort situation and duration;
Latching logic unit, current limiting low-voltage link nearest from fault point described in the locking of described latching logic unit and the current limiting low-voltage link of rectification side.
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| GB2566123B (en) * | 2016-12-07 | 2022-10-19 | Beijing Sifang Automation Co | Tripping method applicable to situation that number of unlocking times exceeds limit since flexible DC control system has been temporarily locked |
| CN106505512B (en) * | 2016-12-07 | 2019-01-08 | 北京四方继保自动化股份有限公司 | Number is unlocked after soft straight control system temporary blocking again to overflow trip method |
| CN106532666B (en) * | 2016-12-30 | 2019-02-15 | 南京南瑞继保电气有限公司 | One kind being suitable for receiving end and is layered extra-high voltage direct-current valve group harmonic protection method |
| CN109861268B (en) * | 2019-03-29 | 2020-08-18 | 西安交通大学 | Nonlinear control method for layered access of extra-high voltage direct current transmission system |
| CN110707738A (en) * | 2019-09-26 | 2020-01-17 | 南方电网科学研究院有限责任公司 | Multi-infeed direct-current power transmission system control optimization method and device and storage medium |
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