CN112952825A - Current transfer suppression method for extra-high voltage multi-terminal direct current transmission system based on current-power deviation value - Google Patents
Current transfer suppression method for extra-high voltage multi-terminal direct current transmission system based on current-power deviation value Download PDFInfo
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- CN112952825A CN112952825A CN202110366072.8A CN202110366072A CN112952825A CN 112952825 A CN112952825 A CN 112952825A CN 202110366072 A CN202110366072 A CN 202110366072A CN 112952825 A CN112952825 A CN 112952825A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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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 invention relates to a current transfer suppression method of an extra-high voltage multi-terminal direct current transmission system based on a current-power deviation value. The method has the advantages that the current-power unbalance of the receiving converter station is introduced into the fixed active power reference value of the valve group, the power reference value is adjusted in real time, the purpose of dynamically adjusting the voltage in the switching-on and switching-off process of the valve group according to the actual current is achieved through power outer loop control, and the suppression of the current transfer of the converter station can be realized on the premise of not needing a PI link. The method achieves the purpose of dynamically adjusting the voltage by adjusting the power reference value in real time, simply and effectively inhibits the overcurrent phenomenon in the current transfer process of the converter station, and has good engineering application prospect. The method provided by the invention has strong reference significance for inhibiting the current transfer of the converter station of the multi-terminal hybrid direct-current transmission system.
Description
Technical Field
The invention belongs to the technical field of power transmission and distribution, and particularly relates to a current transfer suppression method for an extra-high voltage multi-terminal direct current power transmission system based on a current-power deviation value.
Background
The ultra-high voltage hybrid multi-terminal direct current transmission system has advantages in the aspects of long-distance and large-capacity transmission, meanwhile combines the advantages of traditional direct current and flexible direct current, has no problem of commutation failure compared with the traditional direct current, can supply power to a weak receiving terminal alternating current power grid, realizes power transmission of an offshore wind farm, has smaller power loss compared with the flexible direct current, reduces investment cost of a converter and a cable, and has good development prospect.
The extra-high voltage hybrid multi-terminal direct current voltage and current level is high, the current converter is expensive in manufacturing cost, and once the overcurrent problem of the converter station occurs, the consequences are serious. The over-current phenomenon caused by partial transfer of current of other stations to the station is called current transfer, and the root cause of the problem is that the direct current voltage of the station is low, so that the current is transferred to the flexible direct current converter station with low voltage, such as mismatching of the voltage lifting rate between the stations in the switching process of the valve group.
With respect to valve set switching, currently, researchers have proposed effective switching control strategies for both straight and soft valve sets. The switching strategy of the normally straight valve group mainly comprises two modes of small trigger angle unlocking and zero voltage unlocking. When a current transfer problem occurs in the switching-on and switching-off process of the valve group, temporary overcurrent protection can be triggered to lock the converter valve group, so that power transmission is interrupted. The existing valve group switching strategy still has the current transfer risk in the implementation process, and no research is carried out to provide an effective current transfer inhibition strategy.
Disclosure of Invention
The invention provides a current transfer suppression method of an extra-high voltage multi-terminal direct current transmission system based on a current-power deviation value, which comprises the following steps:
step 1: in a control system of a flexible direct current converter station in a valve group, a direct current rated value I is useddcbaseSubtracting the measured value I of the DC current of the stationdcmObtaining the deviation amount Delta I of the direct currentdcI.e. Delta Idc＝Idcbase-Idcm；
Step 2: deviation of DC current by Δ IdcAnd valve group DC voltage rated value UdcbaseMultiplying the power deviation amount Δ P, that is, Δ P ═ Δ Idc·Udcbase；
And step 3: the deviation value delta P of the active power and the original reference value P of the active power are comparedref0Adding to obtain new active power instruction PrefAs reference value for the fixed active power in current vector control, i.e. Pref＝Pref0+ΔP；
And 4, step 4: according to the positive and negative conditions of the direct current deviation value, namely the positive and negative conditions of the power deviation value, the positive and negative conditions of the active power deviation value of the active outer ring of the controller can be known, the change conditions of the active current at the alternating current side and the active power at the alternating current side can be obtained through the control action, and finally, from the energy conservation perspective, the direct current voltage and the direct current of the valve group can be caused to correspondingly change, so that the problem of current transfer is solved.
Drawings
FIG. 1 is a schematic structural diagram of an extra-high voltage hybrid three-terminal direct-current transmission system.
Fig. 2 is a control block diagram of an MMC converter station.
Fig. 3 is a block diagram of a current transfer suppression strategy based on the amount of current-power deviation.
Detailed Description
In order to further explain the principle of the invention, the current transfer suppression strategy of the extra-high voltage multi-terminal direct current transmission system based on the current-power deviation amount is described in detail below with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the invention or its application.
Fig. 1 is a schematic structural diagram of an extra-high voltage hybrid three-terminal direct-current power transmission system. Rated direct voltage is 800kV, sending end converter station is LCC, two receiving end converter stations are MMC, the system adopts the true bipolar wiring mode, every utmost point is established ties by high-end and low end valves and is constituteed, and the single valves of sending end is twelve pulsating current converters, and the single valves of receiving end is half full hybrid MMC.
Fig. 2 is a control block diagram of the MMC converter station. In the system shown in FIG. 1, the LCC1The converter station adopts constant current control, MMC2The station is controlled by fixed DC voltage, MMC3The station adopts constant active power control, and the control block diagram of two MMC stations is shown in figure 2, wherein j 2 and 3 respectively represent MMC2Station, MMC3And (4) a station.
Fig. 3 is a block diagram of a current transfer suppression strategy based on the amount of current-power deviation. It can be seen that the power reference value is adjusted in real time by directly converting the direct current into active power.
Specific implementation steps of the inhibition methods herein are exemplified herein.
Step 1: in MMC2The converter station uses a DC rated value I in a control system of a valve groupdcbaseSubtracting the measured value I of the DC current of the stationdcmObtaining the deviation amount Delta I of the direct currentdcI.e. Delta Idc＝Idcbase-Idcm；
Step 2: deviation of DC current by Δ IdcAnd valve group DC voltage rated value UdcbaseMultiplying to obtain power deviation amount delta P,
i.e. Δ P ═ Δ Idc·Udcbase；
And step 3: the deviation value delta P of the active power and the original reference value P of the active power are comparedref0Adding to obtain new active power instruction PrefAs reference value for the fixed active power in current vector control, i.e. Pref＝Pref0+ΔP；
And 4, step 4: if part of the current is from MMC3Station transfer to MMC2Station, having | Idcm|＞|IdcbaseFrom step 1, | Δ Idc> 0 (receiving end MMC2Is negative), and Δ P > 0 is known from step 2, so | P is known from step 5ref|＜|Pref0| (acceptor MMC)2Negative active power). Due to new active power command absolute value | PrefI is reduced, and the active power deviation delta P of the active outer ring of the controllerm＝Pref-Pm＞0。
As can be seen from FIG. 2, Δ PmObtaining an active current reference value i after a PI link of active power controldcref. Due to deviation of active power Δ Pm＞0，idcrefDecrease in absolute value of (i)dcrefNegative), the actual value i of the active current on the ac side is controlledsdReducing, finally, the active power P of the AC sidesAnd also decreases.
For inverter station MMC2From the viewpoint of energy balance, the energy W of the valve group is inputted to the DC sidedcEqual to the variation quantity delta W of the stored energy of all sub-module capacitors in the valve bankMMCEnergy W output from the valve bank to the AC sidesSum, i.e. Wdc＝ΔWMMC+Ws，
When active power P of AC side of valve groupsWhen the amount is reduced, it is known from the above formulaAnd the variation quantity delta W of the capacitor energy storage of the neutron module in the valve groupMMCIf the voltage is more than 0, the direct current voltage of the valve group is increased, the direct current is reduced, and finally the overcome current is transferred to the MMC2A problem with the station.
Claims (4)
1. A current transfer suppression method for an extra-high voltage multi-terminal direct current transmission system based on a current-power deviation value is characterized in that a current-power unbalance amount of a receiving-end converter station is introduced into a fixed active power reference value of a valve group, the power reference value is adjusted in real time, the purpose of dynamically adjusting the voltage in the switching-on and switching-off process of the valve group according to actual current is achieved through power outer loop control, and the suppression of current transfer of the converter station can be achieved on the premise that a PI link is not needed. The method simply and effectively solves the problem of current transfer of the converter station of the multi-terminal direct-current transmission system. The method comprises the following steps:
step 1: in a control system of a flexible direct current converter station in a valve group, a direct current rated value I is useddcbaseSubtracting the measured value I of the DC current of the stationdcmObtaining the deviation amount Delta I of the direct currentdc；
Step 2: deviation of DC current by Δ IdcAnd valve group DC voltage rated value UdcbaseMultiplying to obtain a power deviation value delta P;
and step 3: the deviation value delta P of the active power and the original reference value P of the active power are comparedref0Adding to obtain new active power instruction PrefAs a reference value for determining active power in current vector control;
and 4, step 4: according to the positive and negative conditions of the direct current deviation value, namely the positive and negative conditions of the power deviation value, the positive and negative conditions of the active power deviation value of the active outer ring of the controller can be known, the change conditions of the active current at the alternating current side and the active power at the alternating current side can be obtained through the control action, and finally, from the energy conservation perspective, the direct current voltage and the direct current of the valve group can be caused to correspondingly change, so that the problem of current transfer is solved.
2. The method for suppressing current transfer of the extra-high voltage multi-terminal direct-current transmission system based on the current-power deviation value according to claim 1, is characterized in that: the invention directly converts direct current into active power, adjusts the power reference value in real time, achieves the aim of dynamically adjusting the voltage of the valve group in the switching process according to the actual current through power outer loop control, and simply and effectively solves the current transfer problem.
3. The method for suppressing current transfer of the extra-high voltage multi-terminal direct-current transmission system based on the current-power deviation value according to claim 1, is characterized in that: the current-power unbalance of the receiving end converter station is introduced into the fixed active power reference value of the valve group, and the current transfer of the converter station can be inhibited on the premise of not needing a PI link.
4. The method for suppressing current transfer of the extra-high voltage multi-terminal direct-current transmission system based on the current-power deviation value according to claim 1, is characterized in that: steps 1, 2, 3 and 4 are an integral content of the invention, and the four steps are interlinked and inseparable, and have corresponding execution sequence.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160308359A1 (en) * | 2012-11-08 | 2016-10-20 | Nr Electric Co., Ltd | Coordination control method of multi-terminal VSC-HVDC transmission system |
| CN108092298A (en) * | 2017-12-05 | 2018-05-29 | 华北电力大学 | The design method of current conversion station active power reference value in a kind of DC grid |
| CN109687499A (en) * | 2018-12-27 | 2019-04-26 | 华北电力大学 | A kind of voltage balancing control method of flexible direct current converter station series connection converter valve |
| CN110829476A (en) * | 2019-10-22 | 2020-02-21 | 华北电力大学 | Balanced control strategy for unbalanced current among multiple MMC converters in extra-high voltage hybrid cascaded direct current transmission system |
| CN111416376A (en) * | 2020-03-13 | 2020-07-14 | 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 | Voltage balancing method for extra-high voltage flexible direct-current constant active power MMC converter station |
| CN112467780A (en) * | 2020-11-30 | 2021-03-09 | 华北电力大学 | Voltage and power rise rate coordination method for three-terminal hybrid direct-current power transmission system |
-
2021
- 2021-04-06 CN CN202110366072.8A patent/CN112952825A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160308359A1 (en) * | 2012-11-08 | 2016-10-20 | Nr Electric Co., Ltd | Coordination control method of multi-terminal VSC-HVDC transmission system |
| CN108092298A (en) * | 2017-12-05 | 2018-05-29 | 华北电力大学 | The design method of current conversion station active power reference value in a kind of DC grid |
| CN109687499A (en) * | 2018-12-27 | 2019-04-26 | 华北电力大学 | A kind of voltage balancing control method of flexible direct current converter station series connection converter valve |
| CN110829476A (en) * | 2019-10-22 | 2020-02-21 | 华北电力大学 | Balanced control strategy for unbalanced current among multiple MMC converters in extra-high voltage hybrid cascaded direct current transmission system |
| CN111416376A (en) * | 2020-03-13 | 2020-07-14 | 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 | Voltage balancing method for extra-high voltage flexible direct-current constant active power MMC converter station |
| CN112467780A (en) * | 2020-11-30 | 2021-03-09 | 华北电力大学 | Voltage and power rise rate coordination method for three-terminal hybrid direct-current power transmission system |
Non-Patent Citations (2)
| Title |
|---|
| 郑安然等: "特高压混合多端直流输电系统中串联换流阀组间的电压平衡控制策略", 《电网技术》 * |
| 郭春义等: "特高压混合级联直流输电系统中多MMC换流器间不平衡电流的均衡控制策略", 《中国电机工程学报》 * |
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