CN103618331B - A kind of flexible direct current transmission converter station DC over-voltage Current limited Control method - Google Patents
A kind of flexible direct current transmission converter station DC over-voltage Current limited Control method Download PDFInfo
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- CN103618331B CN103618331B CN201310609347.1A CN201310609347A CN103618331B CN 103618331 B CN103618331 B CN 103618331B CN 201310609347 A CN201310609347 A CN 201310609347A CN 103618331 B CN103618331 B CN 103618331B
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The present invention is a kind of control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting; when the present invention is directed to flexible direct current power transmission system receiving end current conversion station AC electric network fault or sending end current conversion station direct current one pole disconnection fault; sending end current conversion station power is sent and is limitedly caused DC bus overvoltage; when exceeding protection seting value; the locking of flexible direct current power transmission system and this problem of stopping transport will be caused; propose a kind of sending end current conversion station that reduces fast and absorb meritorious performance number from AC network, suppress the control method that AC line voltage rises.When method of the present invention is applied to flexible direct current power transmission system control; can when electric network fault causes that current conversion station ability to transmit electricity is limited, direct voltage rises fast; by reducing the active power that sending end current conversion station absorbs from AC network; suppressing direct voltage to rise, preventing from causing flexible direct current system locking and stoppage in transit because exceeding protection definite value.
Description
Technical field
The invention belongs to the network stability control technical field of electric power system, particularly a kind of flexible direct current transmission converter station DC over-voltage Current limited Control method.
Background technology
When the AC electrical network of current conversion station or DC side list loop line break down cause Voltage Drop time; DC side active power of output reduces; energy can constantly be stored on the capacitor that is connected in parallel between DC bus; cause DC bus-bar voltage rise and ac-side current excessive; if processed not in time; converter control protection act will be triggered, whole current conversion station of stopping transport, even whole flexible direct current power transmission system.There is following shortcoming like this: the stoppage in transit probability 1) adding flexible direct current power transmission system; 2) if operation current conversion station or operational system are connected with important load, then stoppage in transit current conversion station will cause heavy losses; 3) if two unsynchronized networks are networked by flexible direct current power transmission system, then can cause two unsynchronized networks off-the-lines after stoppage in transit current conversion station, the stable Control protection action of electrical network, loses partial power or load, even cause cascading failure, cause synchronised grids to paralyse; 4) if stoppage in transit current conversion station, the alternating current circuit of its parallel connection may be caused to transship, even Line Flow exceedes its steady limit temporarily, causes the stable Control protection action of electrical network; 5) current conversion station even whole system restart complexity.So reduce fast sending end current conversion station to send active power, reducing direct voltage with not trigger protection action is research emphasis, and the present invention proposes the control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting in order to realize this purpose.
Summary of the invention
The object of the invention is the control method proposing a kind of flexible direct current power transmission system sending end current conversion station overvoltage current limliting; the present invention takes into account the protection requirement of electric power system to flexible direct current system ability to transmit electricity and DC line; voltage across poles is calculated according to the DC line generating positive and negative voltage measured in real time; when voltage across poles exceedes setting value; by reducing the active power value that sending end current conversion station absorbs from AC system fast, realize the control objectives preventing DC line overvoltage.
Technical scheme of the present invention is: the control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting of the present invention, comprises the steps:
1) when a control cycle arrives, measure DC line generating positive and negative voltage in real time and calculate voltage across poles U; And change process is marked to voltage, voltage across poles is defined as voltage base value U
base, the voltage measuring value U that mark is changed
dc=U/U
base;
2) integrated voltage measured value U
dc, voltage setting value U
set, current meritorious reference value P
refand the concrete condition of the enable command EN_OVCL_SCADA of SCADA, calculate the meritorious variation delta P of target control
ref,
Condition one: EN_OVCL_SCADA is 0, and namely SCADA end is forced not carry out overvoltage Current limited Control, meritorious variation delta P
refbe 0, wherein EN_OVCL_SCADA is the current limiting enabled instruction of overvoltage that SCADA sends;
Condition two: EN_OVCL_SCADA is 1, and namely SCADA end carries out overvoltage current limliting, current meritorious reference value P
ref>0, represents DC line and carries active power to current conversion station, does not now need to carry out overvoltage Current limited Control, meritorious variation delta P
refbe 0; Condition three: EN_OVCL_SCADA is 1, and namely SCADA end carries out overvoltage current limliting, current meritorious reference value P
ref≤ 0, represent current conversion station and carry active power to DC line, and control current limiting enabled for triggering overvoltage when EN_OVCLCTRL is 1, namely work as P
ref≤ 0, voltage measuring value U
dcexceed the high threshold of hysteresis loop comparator, EN_OVCLCYRL=1, start overvoltage Current limited Control, reduced to the Low threshold of hysteresis loop comparator by PI feedback regulation control direct current power, EN_OVCLCYRL=0, exit overvoltage Current limited Control;
3) according to meritorious variation delta P
refand from the meritorious reference value P that SCADA issues
ref_SCADA, calculate the meritorious reference value P of target control
ref
4) meritorious reference value P
refbe sent to next stage to control, and wait for that next control cycle goes to step 1 when arriving).
Described step 2) specifically comprise the following steps:
(2.1) calculating voltage measured value U
dcand voltage setting value U
setdifference DELTA U, Δ U=U
dc-U
set, wherein U
setbe set to rated value 1.0p.u.;
(2.2) according to the transfer function of Δ U and proportional integral, voltage-controlled preliminary controlled quentity controlled variable P is calculated
u; The transfer function of proportional integral is:
wherein s is complex frequency, K
pand T
ibe respectively proportionality coefficient and integration time constant, choose K
p=5, T
i=0.05s;
(2.3) to P
ucarry out amplitude limiting processing, calculate required meritorious variation delta P
ref; The processing logic of amplitude limit is for work as P
uduring >0, Δ P
ref=0; Work as P
u<-P
maxtime, Δ P
ref=-P
max; As-P
max<P
uduring <0, Δ P
ref=P
u; The amplitude limit value P of amplitude limiting processing
maxelect the rated capacity of active power as, P
max=1.0p.u..
Described step 2) in the high threshold of hysteresis loop comparator be set to 1.05p.u., the Low threshold of hysteresis loop comparator is set to 0.94p.u..
The present invention takes into account the protection requirement of electric power system to flexible direct current system ability to transmit electricity and DC line; voltage across poles is calculated according to the DC line generating positive and negative voltage measured in real time; when voltage across poles exceedes setting value; by reducing the active power value that sending end current conversion station absorbs from AC system fast, realize the control objectives preventing DC line overvoltage.
Control method of the present invention is positioned at system-level key-course in whole flexible direct-current transmission control system, its major function is the situation of change according to line voltage distribution, active power, the required active power reduced of dynamic calculation sending end current conversion station, rises and overvoltage to suppress direct voltage.The inventive method is the improvement to existing system stage control method, therefore can not need to increase hardware implementing specially.Can be realized by change control program on original flexible direct current control system hardware platform, make flexible direct current power transmission system control to realize the control of active power and direct voltage simultaneously.
The invention has the beneficial effects as follows: when electric network fault causes that current conversion station ability to transmit electricity is limited, direct voltage rises fast; by reducing the active power that sending end current conversion station absorbs from AC network; suppressing direct voltage to rise, preventing from causing flexible direct current system locking and stoppage in transit because exceeding protection definite value.The method has the features such as physical significance is distinct, realization is simple, excellent performance, in the current conversion station level that control method involved by the present invention can be applicable to flexible direct current power transmission system and system-level controller, strengthen current conversion station and system-level controller to the overvoltage control ability of direct voltage.The present invention is the active power that a kind of quick reduction sending end current conversion station absorbs from AC network, avoids the control method of DC over-voltage, and the method has the features such as physical significance is distinct, realization is simple, excellent performance.
Accompanying drawing explanation
Fig. 1 is the control block diagram of overvoltage current limiting control apparatus of the present invention;
Fig. 2 is that overvoltage current limliting of the present invention is from judging enabled device logic control block diagram;
Embodiment
When flexible direct current power transmission system receiving end current conversion station AC electric network fault or sending end current conversion station direct current one pole disconnection fault; sending end current conversion station power is sent and is limitedly caused DC bus overvoltage; when exceeding protection seting value, locking and the stoppage in transit of flexible direct current power transmission system will be caused.In order to improve flexible direct current power transmission system operational reliability; reduce stoppage in transit probability; the control method of a kind of flexible direct current power transmission system sending end current conversion station overvoltage current limliting that the present invention proposes; the present invention takes into account the protection requirement of electric power system to flexible direct current system ability to transmit electricity and DC line; voltage across poles is calculated according to the DC line generating positive and negative voltage measured in real time; when voltage across poles exceedes setting value; by reducing the active power value that sending end current conversion station absorbs from AC system fast, realize the control objectives preventing DC line overvoltage.
Flexible direct current power transmission system sending end current conversion station overvoltage current limiting control apparatus as shown in Figure 1, comprise DC voltage measurement, do difference with voltage setting value to calculate, overvoltage current limliting is from judging enabled device (EN_OVERCTRL), pi regulator, SCADA overvoltage current limliting instruction (EN_OVCL_SCADA) and corresponding amplitude limit link etc.
The control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting comprises the following steps:
1) when a control cycle arrives, measure DC line generating positive and negative voltage in real time and calculate voltage across poles U; And change process is marked, using voltage across poles grade as voltage base value U to voltage
base, the voltage measuring value U that mark is changed
dc=U/U
base;
2) integrated voltage measured value U
dc, voltage setting value U
set, current meritorious reference value P
refand the concrete condition of the enable command EN_OVCL_SCADA of SCADA, calculate the meritorious variation delta P of target control
ref,
Condition one: EN_OVCL_SCADA is 0, and namely SCADA end is forced not carry out overvoltage Current limited Control, meritorious variation delta P
refbe 0;
Condition two: EN_OVCL_SCADA is 1, and namely SCADA end carries out overvoltage current limliting, current meritorious reference value P
ref>0, represents DC line and carries active power to current conversion station, but does not now need to carry out overvoltage current limliting and to gain merit variation delta P
refbe 0;
Condition three: EN_OVCL_SCADA is 1, and namely SCADA end carries out overvoltage current limliting, current meritorious reference value P
ref≤ 0, represent current conversion station and carry active power to DC line, and will control overvoltage is current limiting enabled when EN_OVCLCTRL is 1, as shown in Figure 2, work as P
ref≤ 0, direct voltage U
dcexceed the high threshold of hysteresis loop comparator, in the present embodiment, high threshold is set to 1.05p.u., EN_OVCLCYRL=1, is started overvoltage Current limited Control, is reduced to the Low threshold of hysteresis loop comparator by PI feedback regulation control direct current power, in the present embodiment, Low threshold is set to 0.94p.u., EN_OVCLCYRL=0, exits overvoltage Current limited Control.Concrete operation step is as follows:
(2.1) calculating voltage measured value U
dcand voltage setting value U
setdifference DELTA U, Δ U=U
dc-U
set, wherein U
setgenerally be set to rated value 1.0p.u.;
(2.2) according to the transfer function of Δ U and proportional integral, voltage-controlled preliminary controlled quentity controlled variable P is calculated
u; The transfer function of proportional integral is:
wherein s is complex frequency, K
pand T
ibe respectively proportionality coefficient and integration time constant, can K be chosen
p=5, T
i=0.05s;
(2.3) to P
ucarry out amplitude limiting processing, calculate required meritorious variation delta P
ref; The processing logic of amplitude limit is for work as P
uduring >0, Δ P
ref=0; Work as P
u<-P
maxtime, Δ P
ref=-P
max; As-P
max<P
uduring <0, Δ P
ref=P
u; The amplitude limit value P of amplitude limiting processing
maxgenerally elect the rated capacity of active power as, P
max=1.0p.u.;
3) according to meritorious variation delta P
refand from the meritorious reference value P that SCADA issues
ref_SCADA, calculate the meritorious reference value P of target control
refgenerally there is P
ref=P
ref_SCADA+ Δ P
ref;
4) meritorious reference value P
refbe sent to next stage to control, and wait for that next control cycle goes to step 1 when arriving).
So far, the overvoltage Current limited Control control task that the present invention proposes all completes.
Claims (4)
1. a control method for flexible direct current power transmission system sending end current conversion station overvoltage current limliting, is characterized in that comprising the steps:
1) when a control cycle arrives, measure DC line generating positive and negative voltage in real time and calculate voltage across poles U; And change process is marked to voltage, voltage across poles is defined as voltage base value U
base, the voltage measuring value U that mark is changed
dc=U/U
base;
2) integrated voltage measured value U
dc, voltage setting value U
set, current meritorious reference value P
refand the concrete condition of the enable command EN_OVCL_SCADA of SCADA, calculate the meritorious variation delta P of target control
ref,
Condition one: EN_OVCL_SCADA is 0, and namely SCADA end is forced not carry out overvoltage Current limited Control, meritorious variation delta P
refbe 0, wherein EN_OVCL_SCADA is the current limiting enabled instruction of overvoltage that SCADA sends;
Condition two: EN_OVCL_SCADA is 1, and namely SCADA end carries out overvoltage current limliting, current meritorious reference value P
ref>0, represents DC line and carries active power to current conversion station, does not now need to carry out overvoltage Current limited Control, meritorious variation delta P
refbe 0; Condition three: EN_OVCL_SCADA is 1, and namely SCADA end carries out overvoltage current limliting, current meritorious reference value P
ref≤ 0, represent current conversion station and carry active power to DC line, and control current limiting enabled for triggering overvoltage when EN_OVCLCTRL is 1, namely work as P
ref≤ 0, voltage measuring value U
dcexceed the high threshold of hysteresis loop comparator, EN_OVCLCYRL=1, start overvoltage Current limited Control, reduced to the Low threshold of hysteresis loop comparator by PI feedback regulation control direct current power, EN_OVCLCYRL=0, exit overvoltage Current limited Control;
3) according to meritorious variation delta P
refand from the meritorious reference value P that SCADA issues
ref_SCADA, calculate the meritorious reference value P of target control
ref
4) meritorious reference value P
refbe sent to next stage to control, and wait for that next control cycle goes to step 1 when arriving).
2. the control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting according to claim 1, is characterized in that described step 2) specifically comprise the following steps:
(2.1) calculating voltage measured value U
dcand voltage setting value U
setdifference DELTA U, Δ U=U
dc-U
set, wherein U
setbe set to rated value 1.0p.u.;
(2.2) according to the transfer function of Δ U and proportional integral, voltage-controlled preliminary controlled quentity controlled variable P is calculated
u; The transfer function of proportional integral is:
wherein s is complex frequency, K
pand T
ibe respectively proportionality coefficient and integration time constant, choose K
p=5, T
i=0.05s;
(2.3) to P
ucarry out amplitude limiting processing, calculate required meritorious variation delta P
ref; The processing logic of amplitude limit is for work as P
uduring >0, Δ P
ref=0; Work as P
u<-P
maxtime, Δ P
ref=-P
max; As-P
max<P
uduring <0, Δ P
ref=P
u; The amplitude limit value P of amplitude limiting processing
maxelect the rated capacity of active power as, P
max=1.0p.u..
3. the control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting according to claim 1, is characterized in that described step 2) in the high threshold of hysteresis loop comparator be set to 1.05p.u., the Low threshold of hysteresis loop comparator is set to 0.94p.u..
4. the control method of flexible direct current power transmission system sending end current conversion station overvoltage current limliting according to claim 1; it is characterized in that taking into account the protection requirement of electric power system to flexible direct current system ability to transmit electricity and DC line; voltage across poles is calculated according to the DC line generating positive and negative voltage measured in real time; when voltage across poles exceedes setting value; by reducing the active power value that sending end current conversion station absorbs from AC system fast, realize the control objectives preventing DC line overvoltage.
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| CN107017654B (en) * | 2017-05-31 | 2023-08-01 | 国网四川省电力公司电力科学研究院 | Extra-high voltage direct current transmission control device for inhibiting alternating current temporary overvoltage |
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| CN107732892B (en) * | 2017-11-13 | 2019-04-02 | 国网四川省电力公司电力科学研究院 | A kind of Overvoltage suppressing method based on the idle control of D.C. high voltage transmission |
| CN109347111B (en) * | 2018-10-22 | 2022-12-13 | 国网山东省电力公司济南供电公司 | Active and reactive control method of flexible direct current converter station considering voltage change rate |
| CN109888813B (en) * | 2019-03-04 | 2020-08-21 | 国家电网有限公司 | Method for maximizing power transmission capacity of multi-power source output channel comprising VSC-HVDC |
| CN111276997A (en) * | 2020-04-13 | 2020-06-12 | 国网福建省电力有限公司 | Alternating current fault current limiting method for flexible direct current transmission system |
| CN111682577B (en) * | 2020-06-30 | 2021-11-23 | 华北电力大学 | Transmission power limit calculation method and system for flexible direct current transmission system |
| CN113937806B (en) * | 2020-09-17 | 2023-09-29 | 华北电力大学（保定） | Method for inhibiting overvoltage of wind-solar water passing through sending end of direct-current sending system |
| CN112421591B (en) * | 2020-09-29 | 2024-01-30 | 国网福建省电力有限公司电力科学研究院 | Low-voltage current-limiting fixed value adjusting method for inhibiting flexible direct-current near-zone three-phase short-circuit current |
| CN112217221B (en) * | 2020-10-12 | 2023-06-27 | 国网福建省电力有限公司 | Manual emergency shutdown control method for double-end flexible direct-current transmission converter station |
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