CN110299719A - A kind of flexible HVDC transmission system DC side impedance stability judgment method - Google Patents
A kind of flexible HVDC transmission system DC side impedance stability judgment method Download PDFInfo
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- CN110299719A CN110299719A CN201910717283.4A CN201910717283A CN110299719A CN 110299719 A CN110299719 A CN 110299719A CN 201910717283 A CN201910717283 A CN 201910717283A CN 110299719 A CN110299719 A CN 110299719A
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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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- 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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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]
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Abstract
The invention discloses a kind of flexible HVDC transmission system DC side impedance stability judgment methods.The sufficiently accurate DC side impedance model of flexible direct current converter station can quickly and effectively be established using the present invention, and accurately judge the DC side impedance stability of flexible HVDC transmission system according to the model.DC side impedance model of the invention is simple and clear relative to traditional impedance model, and impedance stability judgment mode is simple, creates conditions for the Rapid Stability analysis of flexible direct current system.
Description
Technical field
The present invention relates to flexible HVDC transmission system technical fields, and in particular to a kind of flexible HVDC transmission system DC side
Impedance stability judgment method.
Background technique
Flexible HVDC transmission system based on voltage-source type converter station is quickly grown, and has effectively promoted the exploitation of new energy
And utilization.But the coupling meeting between the voltage-source type converter station of the capacitive of flexible direct current system and the transmission system of perception
It is likely to result in direct current system unstability, using the possibility of this unstability after inductance limiting short-circuit current in flexible direct current system
Property will increase.The change of current station structure and control system of flexible direct current system are complicated, how to be directed to different type, different control modes
Converter station quickly and effectively establish the stability of sufficiently accurate DC side impedance model analysis direct current system at present in the industry simultaneously
There is no corresponding scheme.
Summary of the invention
For above-mentioned deficiency in the prior art, a kind of flexible HVDC transmission system DC side impedance provided by the invention is steady
Determine judgment method and solves the problems, such as the determination of stability inaccuracy of direct current system.
In order to achieve the above object of the invention, a kind of the technical solution adopted by the present invention are as follows: flexible HVDC transmission system direct current
Side impedance stability judgment method, comprising the following steps:
S1, by the impedance of the inverter DC side impedance that obtains converter station in parallel with the capacitor of converter station DC side, and will
The DC side impedance of converter station adds the impedance of power transmission line, obtains the DC side impedance model of entire direct current system；
S2, the pole for drawing DC side impedance in a coordinate system according to DC side impedance model；
S3, judge DC side impedance pole whether coordinate system right half plane, if then decision-making system DC side hinder
Resist it is unstable, otherwise, it is determined that system dc side impedance stabilization.
Further: the DC side impedance model of direct current system in the step S1 specifically:
In above formula, ZsysFor the DC side impedance of direct current system, ZnetFor power line impedance, ZAAnd ZBRespectively converter station A and
The Converter DC-side impedance of converter station B, s are Laplace operator, CeAAnd CeBThe respectively direct current of converter station A and converter station B
Lateral capacitance.
Further: the Converter DC-side impedance Z of the converter station AAWith the Converter DC-side impedance Z of converter station BB
Value be control active power converter station Converter DC-side impedance ZP, control DC voltage converter station inverter direct current
Side impedance ZVOr the Converter DC-side impedance Z of sagging control converter stationD。
Further: the Converter DC-side impedance Z of the control active power converter stationPCalculation formula are as follows:
In above formula, Vdc0And Pdc0The respectively rating operating voltage of converter station and rated output active power.
Further: the Converter DC-side impedance Z of the control DC voltage converter stationVCalculation formula are as follows:
In above formula, KVIt (s) is the outer ring PI controller at control voltage station, its calculation formula is:
KV(s)=kvp+skip
In above formula, kvpAnd kipRespectively ratio and integral parameter.
Further: the Converter DC-side impedance Z of the sagging control converter stationDCalculation formula are as follows:
In above formula, KdIt (s) is the outer ring PI controller under sagging control model, kdFor sagging coefficient.
The invention has the benefit that
1. the sufficiently accurate DC side impedance model of flexible direct current converter station can quickly and effectively be established using the present invention,
And the DC side impedance stability of flexible HVDC transmission system is accurately judged according to the model.
2. DC side impedance model of the invention is simple and clear relative to traditional impedance model, impedance stability judgement side
Formula is simple, creates conditions for the Rapid Stability analysis of flexible direct current system.
Detailed description of the invention
Fig. 1 is the topological structure schematic diagram of both ends flexible direct current system in the embodiment of the present invention；
Fig. 2 is the DC side equivalent impedance circuit diagram of both ends flexible direct current system in the embodiment of the present invention；
Fig. 3 is flow chart of the present invention；
Fig. 4 in the DC side impedance and emulation of both ends flexible direct current system under master & slave control in the embodiment of the present invention by surveying
The impedance contrast figure taken；
Fig. 5 in the DC side impedance and emulation of both ends flexible direct current system under control sagging in the embodiment of the present invention by surveying
The impedance contrast figure taken；
Fig. 6 is the zero point of the DC side impedance of both ends flexible direct current system under master & slave control in the embodiment of the present invention in current limliting
Trajectory diagram when inductance changes；
Fig. 7 is the electric current of both ends flexible direct current system under master & slave control in the embodiment of the present invention when current-limiting inductance changes
Variation diagram.
Specific embodiment
A specific embodiment of the invention is described below, in order to facilitate understanding by those skilled in the art this hair
It is bright, it should be apparent that the present invention is not limited to the ranges of specific embodiment, for those skilled in the art,
As long as various change is in the spirit and scope of the present invention that the attached claims limit and determine, these variations are aobvious and easy
See, all are using the innovation and creation of present inventive concept in the column of protection.
Both ends direct current system as shown in Figure 1.It is right respectively to need in the DC side impedance modeling to the direct current system
Converter station A and converter station B are modeled.For different types of converter station, its modeling process is consistent.Carried out to converter station
Need the capacitor by converter station independent from converter station when modeling, as shown in Figure 2.
As shown in figure 3, a kind of flexible HVDC transmission system DC side impedance stability judgment method, comprising the following steps:
S1, by the impedance of the inverter DC side impedance that obtains converter station in parallel with the capacitor of converter station DC side, and will
The DC side impedance of converter station adds the impedance of power transmission line, obtains the DC side impedance model of entire direct current system；
Z in Fig. 2AIt is exactly the DC side impedance model of the inverter of converter station A, the Z in Fig. 2BIt is exactly changing for converter station B
Flow the DC side impedance of device.Z in Fig. 2netIt is the impedance of transmission line of electricity.Entire direct current system has been measured in the outlet converter station B
Impedance can be expressed as:
In above formula, ZsysFor the DC side impedance of direct current system, ZnetFor power line impedance, ZAAnd ZBRespectively converter station A and
The Converter DC-side impedance of converter station B, s are Laplace operator, CeAAnd CeBThe respectively direct current of converter station A and converter station B
Lateral capacitance.
By the DC side of the inverter of the converter station under the different control modes obtained under simplified modeling and details modeling
Impedance replaces ZsysZ in expression formulaAOr ZBIt can be obtained by under different control modes, simplify under the modeling in detail of modeling and tradition
DC side system impedance.
The Converter DC-side impedance Z of the converter station AAWith the Converter DC-side impedance Z of converter station BBValue be control
The Converter DC-side impedance Z of active power converter station processedP, control DC voltage converter station Converter DC-side impedance ZVOr
The Converter DC-side impedance Z of sagging control converter stationD。
When converter station A controls active power, and converter station B controls DC voltage, simplifies model lower system at this time
DC side impedance ZsysIt can be expressed as:
When converter station A controls active power, and converter station B controls DC voltage, the lower system of tradition modeling in detail at this time
The DC side impedance Z of systemsysIt can be expressed as:
Active power is controlled in converter station A, when converter station B is in sagging control, simplifies model lower system at this time
DC side impedance ZsysIt can be expressed as:
Active power is controlled in converter station A, when converter station B is in sagging control, the lower system of tradition modeling in detail at this time
The DC side impedance Z of systemsysIt can be expressed as:
The Converter DC-side impedance Z of the control active power converter stationPCalculation formula are as follows:
In above formula, Vdc0And Pdc0The respectively rating operating voltage of converter station and rated output active power.
The Converter DC-side impedance Z of the control DC voltage converter stationVCalculation formula are as follows:
In above formula, KVIt (s) is the outer ring PI controller at control voltage station, its calculation formula is:
KV(s)=kvp+skip
In above formula, kvpAnd kipRespectively ratio and integral parameter.
The Converter DC-side impedance Z of the sagging control converter stationDCalculation formula are as follows:
In above formula, KdIt (s) is the outer ring PI controller under sagging control model, kdFor sagging coefficient.
Using traditional DC side impedance method for building up, it is available control active power station and control DC voltage station
And the DC side impedance expression difference of sagging control station is as follows:
In above formula, idc0For DC side rated current, ucd0、ucq0And id0、iq0Respectively exchange the voltage rating of side dq axis
And electric current, md0、mq0Respectively dq axis modulation degree, KpIt (s) is control active power station power outer ring PI controller, Kp(s)=kpp+
skpi, kppAnd skpiRespectively ratio and integral parameter, KdIt (s) is that the converter station outer ring PI that control model is sagging control is controlled
Device, Kd(s)=kdp+skdi, kdpAnd skdiRespectively ratio and integral parameter, kdFor sagging coefficient.
GPWMFor the transmission function during PWM, Gu0、Gi0、ZT、GLT、Gc, E be middle coefficient, its calculation formula is:
In above formula, LTAnd RTRespectively converter power transformer inductance and resistance, KcIt (s) is inner ring current controller, Kc(s)=
kcp+skci, kcpAnd skciRespectively ratio and integral coefficient, ωbTo exchange side angle frequency reference value, generally 50Hz.
S2, the pole for drawing DC side impedance in a coordinate system according to DC side impedance model；
S3, judge DC side impedance pole whether coordinate system right half plane, if then decision-making system DC side hinder
Resist it is unstable, otherwise, it is determined that system dc side impedance stabilization.
The resistance measured in impedance modeler model, tradition modeler model and simulation model in detail under different controls, will be simplified
Anti- bode schemes comparison.Fig. 4 is surveyed in the DC side impedance and emulation for being the both ends flexible direct current system under master & slave control
The impedance contrast taken.Fig. 5 is the resistance that is measured in the DC side impedance and emulation of the both ends flexible direct current system under sagging control
Anti- comparison.It can be seen that the DC side established simplifies impedance model and DC side tradition detailed impedance model and measures straight
Stream side impedance is consistent, and the simplification impedance model established can be used for the stability analysis of direct current system.
Fig. 6 is the DC side impedance Z of the both ends flexible direct current system under master & slave controlsysPole current-limiting inductance change
When track.It can be seen that in current-limiting inductance LlimAfter 0.4H, the zero point of system passes through the imaginary axis to positive half-plane.So being
System can be unstable.Fig. 7 is variation feelings of the electric current of the both ends flexible direct current system under master & slave control in current-limiting inductance variation
Condition.It can be seen that consistent with theory analysis, system is in current-limiting inductance LlimStabilization is lost later greater than 0.4H.
Claims (6)
1. a kind of flexible HVDC transmission system DC side impedance stability judgment method, which comprises the following steps:
S1, by the impedance of the inverter DC side impedance that obtains converter station in parallel with the capacitor of converter station DC side, and by the change of current
The DC side impedance stood adds the impedance of power transmission line, obtains the DC side impedance model of entire direct current system；
S2, the pole for drawing DC side impedance in a coordinate system according to DC side impedance model；
S3, judge DC side impedance pole whether coordinate system right half plane, if then the impedance of decision-making system DC side is not
Stablize, otherwise, it is determined that system dc side impedance stabilization.
2. flexible HVDC transmission system DC side impedance stability judgment method according to claim 1, which is characterized in that
The DC side impedance model of direct current system in the step S1 specifically:
In above formula, ZsysFor the DC side impedance of direct current system, ZnetFor power line impedance, ZAAnd ZBRespectively converter station A and the change of current
It stands the Converter DC-side impedance of B, s is Laplace operator, CeAAnd CeBThe respectively DC side of converter station A and converter station B electricity
Hold.
3. flexible HVDC transmission system DC side impedance stability judgment method according to claim 2, which is characterized in that
The Converter DC-side impedance Z of the converter station AAWith the Converter DC-side impedance Z of converter station BBValue be control wattful power
The Converter DC-side impedance Z of rate converter stationP, control DC voltage converter station Converter DC-side impedance ZVOr sagging control
The Converter DC-side impedance Z of converter stationD。
4. flexible HVDC transmission system DC side impedance stability judgment method according to claim 3, which is characterized in that
The Converter DC-side impedance Z of the control active power converter stationPCalculation formula are as follows:
In above formula, Vdc0And Pdc0The respectively rating operating voltage of converter station and rated output active power.
5. flexible HVDC transmission system DC side impedance stability judgment method according to claim 4, which is characterized in that
The Converter DC-side impedance Z of the control DC voltage converter stationVCalculation formula are as follows:
In above formula, KVIt (s) is the outer ring PI controller at control voltage station, its calculation formula is:
KV(s)=kvp+skip
In above formula, kvpAnd kipRespectively ratio and integral parameter.
6. flexible HVDC transmission system DC side impedance stability judgment method according to claim 4, which is characterized in that
The Converter DC-side impedance Z of the sagging control converter stationDCalculation formula are as follows:
In above formula, KdIt (s) is the outer ring PI controller under sagging control model, kdFor sagging coefficient.
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| CN110829421A (en) * | 2019-11-15 | 2020-02-21 | 东北电力大学 | System impedance modeling method for VSC cascaded LLC |
| CN112636382A (en) * | 2020-12-21 | 2021-04-09 | 中国科学院电工研究所 | Star-shaped alternating current-direct current power distribution system operation stability analysis method |
| CN112636381A (en) * | 2020-12-21 | 2021-04-09 | 中国科学院电工研究所 | Hand-in-hand type operation stability analysis method for alternating current and direct current power distribution and utilization system |
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| CN112636382A (en) * | 2020-12-21 | 2021-04-09 | 中国科学院电工研究所 | Star-shaped alternating current-direct current power distribution system operation stability analysis method |
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