CN104537158B - Modeling method and synchronous model machine suitable for VSC HVDC systems - Google Patents
Modeling method and synchronous model machine suitable for VSC HVDC systems Download PDFInfo
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Abstract
The invention provides a kind of modeling method suitable for VSC HVDC systems, including：Step 1：Averagely simplify rectification link；Step 2：Averagely simplify inversion link；Step 3：Averagely simplify direct current transmission link.The present invention also provides corresponding current transformer and synchronous model machine.Rectification link, direct current transmission link and the inversion link of synchronous model machine in the present invention use mean value model, form complete current transformer mean value model, suitable for wind farm grid-connected, in the case where not being related to converter control method, most of simulation requirements can be met.
Description
Technical field
The present invention relates to electrical engineering field, specifically a kind of modeling method suitable for VSC-HVDC systems and synchronous sample
Machine.
Background technology
In recent years, Oversea wind power generation and its conveying are the focuses of the new energy industry such as wind-powered electricity generation.With Power Electronic Technique
Fast development, voltage source converter type DC transmission system (VSC-HVDC) be based on voltage source converter (VSC) and series connection absolutely
Edge grid bipolar transistor (IGBT) is also ripe day by day, turns into a kind of novel means of offshore wind farm power Transmission.At present, existing skill
Art still uses conventional model, and real Time Dynamic Simulation or development 1 are carried out based on computer simulation software:10 or 1：100 it is small-sized
Synchronous model machine, study Oversea wind power generation VSC-HVDC systems.Converter topology relative maturity, as a rule not
Studied for converter control method, in terms of spending great effort to be used for model cootrol.In commercial Application, VSC-
The system-wide cores of HVDC are current transformers, no matter from volume or economic aspect, controlled source will be better than current transformer.
Conventional model has the disadvantage that：
1st, current transformer control strategy variation, pwm signal modulation are complicated；
2nd, in simulation model, whole system model buildings are complicated, and difficulty is high；
3rd, simulation calculation workload is big, and simulation velocity is slow；
When the 4th, developing small synchronous model machine, current transformer volume is larger, and economic benefit is low.
The content of the invention
For in the prior art the defects of, it is an object of the invention to provide a kind of modeling side suitable for VSC-HVDC systems
Method and synchronous model machine.The purpose of the present invention is on the premise of simulation accuracy is ensured, for General Promotion VSC-HVDC systems
Mathematical computations amount in simulation velocity, Optimized model topological structure and reduction emulation, and simplify the difficulty for developing synchronous model machine
Degree, after proposing by the way that the detailed model based on IGBT converter is simplified into mean value model, then is substituted into original system model, is come
Simplify VSC-HVDC system models.
According to a kind of modeling method suitable for VSC-HVDC systems provided by the invention, comprise the following steps：
Step 1：Averagely simplify rectification link, the rectification Link Model after the averaged simplification of rectification link, be specially：
The input of rectification Link Model is the perunit value Uavg_rotor_ of current transformer rectification side three-phase voltage reference signal
Conv, by A, B two-phase therein and B, C two-phase perunit value by subtracting each other, two line voltages are obtained, then again with two obtained
Line voltage respectively with DC voltage VdcIt is multiplied, then two voltages by the acquisition that is multiplied are averaged to obtain average voltage respectively
Vab_avg and average voltage Vbc_avg；Finally by average voltage Vab_avg and average voltage Vbc_avg through amplitude limit (+Vdc,-
Vdc) export final magnitude of voltage afterwards and be：The average voltage Vab_rc of A, B two-phase voltage exported after amplitude limit and after amplitude limit
The average voltage Vbc_rc of B, C two-phase voltage of output；
Step 2：Averagely simplify inversion link, the inversion Link Model after the averaged simplification of inversion link, be specially：
The input of inversion Link Model is the three-phase alternating voltage perunit value Uavg_grid_conv of current transformer inverter side, will
A, B two-phase and B, C two-phase voltage perunit value therein obtains two line voltages, then again with two lines obtained by subtracting each other
Voltage and DC voltage VdcIt is multiplied, then two voltages by the acquisition that is multiplied are averaged to obtain average voltage Vab_ respectively
Avg and average voltage Vbc_avg, is converted to current transformer real output value, most afterwards through amplitude limit (+Vdc,-Vdc) export afterwards finally
Magnitude of voltage is：The average voltage Vab_gc of A, B two-phase voltage exported after amplitude limit and B, C two-phase electricity exported after amplitude limit
The average voltage Vbc_gc of pressure；
Step 3：Averagely simplify direct current transmission link, the direct current transmission Link Model after the averaged simplification of direct current transmission link
The rectification side and inverter side of current transformer are connected to, the input of direct current transmission Link Model is the three of current transformer rectification side and inverter side
Phase current, respectively after scaling, pass through following two prime power formula and average voltage Vab_rc, average voltage
Vbc_rc, average voltage Vab_gc, average voltage Vbc_gc are associated：
Pac=Vab·Ia-Vbc·Ic (1)
Pdc=Vdc·Idc (2)
Wherein, PacRepresent the exchange active power of input, VabThe average voltage Vab_rc and step 2 that expression step 1 obtains
Obtained average voltage Vab_gc, IaRepresent the A phase currents collected, VbcRepresent the average voltage Vbc_ that step 1 obtains
The average voltage Vbc_gc, I that rc and step 2 obtaincRepresent the C phase currents collected, PdcRepresent direct current active power, VdcRepresent
DC voltage, IdcDC current is represented, represents to be multiplied.
Preferably, step 3：Averagely simplify direct current transmission link, the direct current transmission after the averaged simplification of direct current transmission link
Link Model, it is specially：
One input of direct current transmission Link Model is inverter side three-phase alternating current perunit value Iabc_grid_conv_
Pu, scaling be converted into after actual value of A phase currents therein is obtained into the average voltage Vab_ of A, B two-phase voltage with step 2
The product of gc multiplications subtracts scaling be converted into after actual value of C phase currents therein and obtains being averaged for B, C two-phase voltage with step 2
The product of voltage Vbc_gc multiplications, that is, obtain the exchange active-power P of inverter sideac, by the exchange active power of obtained inverter side
PacDivided by DC voltage Vdc, then DC current Idc_gc corresponding to inverter side is obtained；
Another input of direct current transmission Link Model is rectification side three-phase alternating current perunit value Iabc_rotor_pu,
Scaling be converted into after actual value of A phase currents therein is obtained into the average voltage Vab_rc phases of A, B two-phase voltage with step 1
The product multiplied subtracts scaling be converted into after actual value of C phase currents therein and obtains the average voltage Vbc_ of B, C two-phase with step 1
The product of rc multiplications, that is, obtain the exchange active-power P of rectification sideac, by the exchange active-power P of obtained rectification sideacIt is divided by straight
Flow voltage Vdc, then DC current Idc_rc corresponding to rectification side is obtained；
Obtained DC current Idc_gc and DC current Idc_rc difference is subjected to PI regulations, you can obtain DC voltage
Vdc。
According to a kind of current transformer provided by the invention, the equivalent model of the current transformer is or is applied to including above-mentioned
The model that the modeling method of VSC-HVDC systems is established.
According to a kind of synchronous model machine provided by the invention, including following device：
First device：For averagely simplifying rectification link；Rectification Link Model after the averaged simplification of rectification link, specifically
For：
The input of rectification Link Model is the perunit value Uavg_rotor_ of current transformer rectification side three-phase voltage reference signal
Conv, by A, B two-phase therein and B, C two-phase perunit value by subtracting each other, two line voltages are obtained, then again with two obtained
Line voltage respectively with DC voltage VdcIt is multiplied, then two voltages by the acquisition that is multiplied are averaged to obtain average voltage respectively
Vab_avg and average voltage Vbc_avg；Finally by average voltage Vab_avg and average voltage Vbc_avg through amplitude limit (+Vdc,-
Vdc) export final magnitude of voltage afterwards and be：The average voltage Vab_rc of A, B two-phase voltage exported after amplitude limit and after amplitude limit
The average voltage Vbc_rc of B, C two-phase voltage of output；
Second device, for averagely simplifying inversion link；Inversion Link Model after the averaged simplification of inversion link, specifically
For：
The input of inversion Link Model is the three-phase alternating voltage perunit value Uavg_grid_conv of current transformer inverter side, will
A, B two-phase and B, C two-phase voltage perunit value therein obtains two line voltages, then again with two lines obtained by subtracting each other
Voltage and DC voltage VdcIt is multiplied, then two voltages by the acquisition that is multiplied are averaged to obtain average voltage Vab_ respectively
Avg and average voltage Vbc_avg, is converted to current transformer real output value, most afterwards through amplitude limit (+Vdc,-Vdc) export afterwards finally
Magnitude of voltage is：The average voltage Vab_gc of A, B two-phase voltage exported after amplitude limit and B, C two-phase electricity exported after amplitude limit
The average voltage Vbc_gc of pressure；
3rd device, for averagely simplifying direct current transmission link；Direct current transmission after the averaged simplification of direct current transmission link
Link Model is connected to the rectification side and inverter side of current transformer, and the input of direct current transmission Link Model is current transformer rectification side and inverse
Become the three-phase current of side, respectively after scaling, by following two prime power formula and average voltage Vab_rc,
Average voltage Vbc_rc, average voltage Vab_gc, average voltage Vbc_gc are associated：
Pac=Vab·Ia-Vbc·Ic (1)
Pdc=Vdc·Idc (2)
Wherein, PacRepresent the exchange active power of input, VabRepresent the obtained average voltage Vab_rc of first device and the
The average voltage Vab_gc, I that two devices obtainaRepresent the A phase currents collected, VbcWhat expression expression first device obtained is averaged
The average voltage Vbc_gc, I that voltage Vbc_rc and second device obtaincRepresent the C phase currents collected, PdcRepresent that direct current is active
Power, VdcRepresent DC voltage, IdcDC current is represented, represents to be multiplied.
Preferably, the direct current transmission Link Model after the averaged simplification of direct current transmission link, it is specially：
One input of direct current transmission Link Model is inverter side three-phase alternating current perunit value Iabc_grid_conv_
Pu, scaling be converted into after actual value of A phase currents therein is obtained into the average voltage of A, B two-phase voltage with second device
The product of Vab_gc multiplications subtracts scaling be converted into after actual value of C phase currents therein and obtains B, C two-phase electricity with second device
The product of the average voltage Vbc_gc multiplications of pressure, that is, obtain the exchange active-power P of inverter sideac, by the exchange of obtained inverter side
Active-power PacDivided by DC voltage Vdc, then DC current Idc_gc corresponding to inverter side is obtained；
Another input of direct current transmission Link Model is rectification side three-phase alternating current perunit value Iabc_rotor_pu,
Scaling be converted into after actual value of A phase currents therein is obtained into the average voltage Vab_ of A, B two-phase voltage with first device
The product of rc multiplications subtracts scaling be converted into after actual value of C phase currents therein and obtains being averaged for B, C two-phase with first device
The product of voltage Vbc_rc multiplications, that is, obtain the exchange active-power P of rectification sideac, by the exchange active power of obtained rectification side
PacDivided by DC voltage Vdc, then DC current Idc_rc corresponding to rectification side is obtained；
Obtained DC current Idc_gc and DC current Idc_rc difference is subjected to PI regulations, you can obtain DC voltage
Vdc。
Compared with prior art, the present invention has following beneficial effect：
1st, rectification link, direct current transmission link and the inversion link of the synchronous model machine in the present invention use mean value model,
Complete current transformer mean value model is formed,, can in the case where not being related to converter control method suitable for wind farm grid-connected
To meet most of simulation requirements.
2nd, using current transformer mean value model without considering complicated current transformer control strategy, model complexity step-down, mould
Type is built easily.
3rd, traditional current transformer detailed model based on IGBT is substituted using current transformer mean value model so that VSC-HVDC systems
System model topology structure greatly simplifies.
4th, using current transformer mean value model, without considering that electro-magnetic transient etc. calculates, the mathematical computations amount of emulation is big
Big to reduce, simulation time shortens, and simulation efficiency improves.
5th, in the case of guarantee is able in many performances of current transformer, if using the simulation model, its simulation result with
Former converter system in detail reaches unanimity, then can use the voltage drawn under the simulation model, and current status select to remove unsteady flow
Passive device and adjustment transformer parameter outside device etc..
6th, the present invention in the industry, establishes synchronous simplified model, in the situation that current transformer performance is able to ensure to big system
Under, during to the type selecting of other passive devices or other materials, using the simplified model and corresponding synchronous model machine, with controlled electricity
Source replaces current transformer, can greatly improve economic benefit and resource utilization.
Brief description of the drawings
The detailed description made by reading with reference to the following drawings to non-limiting example, further feature of the invention,
Objects and advantages will become more apparent upon：
Fig. 1 is the mean value model of rectification link.
Fig. 2 is the mean value model of inversion link.
Fig. 3 is the mean value model of direct current transmission link.
Fig. 4 is the encapsulation of current transformer mean value model.
Fig. 5 is the VSC-HVDC system simulation models based on current transformer mean value model.
Fig. 6 is simplified model active power waveform.
Fig. 7 is conventional model active power waveform.
Fig. 8 is simplified model DC voltage waveform.
Fig. 9 is conventional model DC voltage waveform.
Embodiment
With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill to this area
For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention
Protection domain.
The present invention is in order to simplify VSC-HVDC total systems model and its synchronous model machine, it is contemplated that mean value model was simplifying
The numerous and diverse degree of VSC-HVDC systems, the time varying characteristic without considering system in detail can be ignored in journey, it is proposed that using current transformer
Mean value model substitute traditional current transformer detailed model based on IGBT.For three links of current transformer, i.e. rectification, direct current
Transmission and inversion link construct mean value model respectively, are finally uniformly encapsulated as the mean value model of whole current transformer, so as to
The synchronous model machine that can be simplified.The present invention is that a kind of simplifying based on mean value model is improved, its simple and practical, lifting
Mathematical computations amount in the simulation velocity of VSC-HVDC systems, Optimized model topological structure and reduction emulation, while can also protect
Demonstrate,prove simulation accuracy.The present invention be applied to it is wind farm grid-connected, in the case where not being related to converter control method, big portion can be met
Divide simulation requirements.
It is a feature of the present invention that：
(1) traditional current transformer model is simplified from three rectification, inversion, direct current transmission links；
(2) rectification in VSC-HVDC systems and the voltage and electric current of inversion both sides are gathered, with corresponding equivalent controlled electricity
Source substitutes current transformer；
(3) the synchronous simplified model of original system and synchronous model machine are established using the method for simplifying；
(4) in VSC-HVDC systems, to select in addition to inverter controller other elements (such as passive device,
Or transformer etc.) when or investigate element function, take the present invention simplified model and synchronous model machine, then need not design current transformer
And its controller.So as to greatly improve economic benefit and resource utilization.
Modeling method provided by the invention, as shown in figure 1, the input of the link is rectification side three-phase voltage reference signal
Perunit value, subtract each other by two-phase, phase voltage is converted into line voltage, then with obtained line voltage and DC voltage VdcIt is multiplied,
This DC voltage can be drawn by direct current transmission link, be that current transformer actually enters value by the voltage conversion of acquisition, finally passed through again
Amplitude limit (+Vdc,-Vdc) final magnitude of voltage is exported afterwards.As shown in Fig. 2 the structure of rectification and inversion both sides is basically identical, so inverse
Become side mean value model and rectification side it is also essentially the same.The input of inversion link is the three-phase dc voltage of inverter side, is turned
Change into after line voltage and VdcIt is multiplied, obtains exporting again after limiting voltage.As shown in figure 3, the input of direct current transmission link is
The three-phase current of rectification side and inverter side, after scaling, by formula (1), formula (2) by obtain before four voltages
Amount associates.The active power of rectification side obtains two electricity by rectification side three-phase current and collector ring section mean value model before
Pressure is calculated, the three-phase current that the active power of inverter side has inverter side obtained with inversion link mean value model before two
Individual voltage is calculated.Assuming that noenergy is lost, i.e. rectification side, active power that power network injects to transverter and transverter it is straight
It is equal to flow side power；Inverter side, DC side power is equal with the active power at the nearly user terminal of transverter, by formula (2), draws
DC current (the note on both sides：Electric current is obtained by the equal backstepping of power, behind adjusted to obtain DC voltage according to PI).By both sides
Input of the difference for the DC current being calculated as DC capacitor, finally obtains DC voltage by integral element.The present invention
The current transformer mean value model of the current transformer of offer, as shown in figure 4, the mean value model has 4 inputs, it correspond to respectively whole
Stream, the input of three links of direct current transmission and inversion, are rectification side three-phase voltage and three-phase current and inverter side three-phase electricity respectively
Pressure and three-phase current.Meanwhile also have 5 output ports, it is two voltages, the output of inversion link of the output of rectification link respectively
The DC voltage value that two voltages and direct current transmission link obtain.
More specifically, modeling method provided by the invention is a kind of simplification of current transformer model in system to VSC-HVDC
Method, comprise the following steps：
Step 1：Averagely simplify rectification link.
As shown in figure 1, it is the rectification Link Model after rectification link simplifies.The input of rectification Link Model is that current transformer is whole
The perunit value Uavg_rotor_conv of side three-phase voltage reference signal is flowed, wherein A, B two-phase and B, C two-phase perunit value will be passed through
Subtract each other, two line voltages can be obtained, then again with obtain two line voltages respectively with DC voltage VdcIt is multiplied, this direct current
Press VdcIt can be obtained, then two voltages of the acquisition that is multiplied are averaged respectively to obtain by direct current transmission Link Model below
To average voltage Vab_avg and average voltage Vbc_avg, be converted to current transformer and actually enter value；Most afterwards through amplitude limit (+Vdc,-
Vdc) export final magnitude of voltage afterwards and be：The average voltage Vab_rc of A, B two-phase voltage exported after amplitude limit and after amplitude limit
The average voltage Vbc_rc of B, C two-phase voltage of output.
In Fig. 1：
Uavg_rotor_conv is represented：The perunit value of current transformer rectification side three-phase voltage reference signal；
0.5 represents：By A, B two-phase voltages are averaged
Vab_avg is represented：A, the average voltage of B two-phase voltages
Vbc_avg is represented：B, the average voltage of C two-phase voltages
Up is represented：Output voltage limit
Lo is represented：Output voltage lower limit
U is represented：Input, represent voltage
Y is represented：Output, represent voltage
Vab_rc is represented：The average voltage of A, B two-phase voltage exported after amplitude limit
Vbc_rc is represented：The average voltage of B, C two-phase voltage exported after amplitude limit
Step 2：Averagely simplify inversion link.
As shown in Fig. 2 the symmetrical configuration of rectification and inverter side, so the mean value model of inverter side and rectification side basic one
Cause.As shown in Fig. 2 it is the inversion Link Model after inversion link averagely simplifies.The input of inversion Link Model is that current transformer is inverse
Become the three-phase alternating voltage perunit value Uavg_grid_conv of side, A, B two-phase therein and B, C two-phase voltage perunit value are passed through
Subtract each other, two line voltages can be obtained, then again with two line voltages obtained and DC voltage VdcIt is multiplied, this DC voltage
VdcIt can be obtained by direct current transmission Link Model below, then two voltages by the acquisition that is multiplied are averaged to obtain respectively
Average voltage Vab_avg and average voltage Vbc_avg, is converted to current transformer real output value, most afterwards through amplitude limit (+Vdc,-Vdc)
Exporting final magnitude of voltage afterwards is：The average voltage Vab_gc of A, B two-phase voltage exported after amplitude limit and after amplitude limit it is defeated
The average voltage Vbc_gc of B, C two-phase voltage gone out.
In Fig. 2：
Uavg_grid_conv is represented：The three-phase alternating voltage perunit value that inverter side collects；
0.5 represents：By A, B or B, C two-phase voltage are averaged
Vab_avg is represented：A, the average voltage of B two-phase voltages
Vbc_avg is represented：B, the average voltage of C two-phase voltages
Up is represented：Output voltage limit
Lo is represented：Output voltage lower limit
U is represented：Input, represent voltage
Y is represented：Output, represent voltage
Vab_gc is represented：The average voltage of A, B two-phase voltage exported after amplitude limit
Vbc_gc is represented：The average voltage of B, C two-phase voltage exported after amplitude limit
Step 3：Averagely simplify direct current transmission link.
As shown in figure 3, direct current transmission Link Model is connected to the rectification side and inverter side of current transformer, direct current transmission link mould
The input of type is the three-phase current of current transformer rectification side and inverter side, after scaling, passes through following two basic training
Rate formula associates with four voltages obtained before：
Pac=Vab·Ia-Vbc·Ic (1)
Pdc=Vdc·Idc (2)
Wherein, PacRepresent the exchange active power of input, VabThe average voltage Vab_rc and step 2 that expression step 1 obtains
Obtained average voltage Vab_gc, IaRepresent the A phase currents collected, VbcRepresent the average voltage Vbc_ that step 1 obtains
The average voltage Vbc_gc, I that rc and step 2 obtaincRepresent the C phase currents collected, PdcRepresent direct current active power, VdcRepresent
DC voltage, IdcDC current is represented, represents to be multiplied；
In Fig. 3：
Iabc_grid_conv_pu is represented：Net side is the three-phase alternating current perunit value that inverter side collects；
pu->A is represented：It is scaling, perunit value is converted into actual value；
Vab_gc is represented：Step 2 obtains the average voltage level of A, B phase；
Vbc_gc is represented：Step 2 obtains the average voltage level of B, C phase；
PacRepresent：Exchange active power；
VdcRepresent：DC voltage；
Idc_gc is represented：The DC current being calculated by net side active power and DC voltage；
Iabc_rotor_pu is represented：The three-phase alternating current perunit value that rectification side collects；
Vab_rc is represented：Step 1 obtains the average voltage level of A, B phase；
Vbc_rc is represented：Step 1 obtains the average voltage level of B, C phase；
Idc_rc is represented：The DC current being calculated by rectification side active power and DC voltage；
1/C is represented：Proportional component；
Discrete Time integrator are represented：Integral element；
K is represented：Integral element coefficient, it can adjust；
Ts is represented：Sampling time；
Z-1 is represented：The integrated form for converting to obtain to Z domains by time domain；
VdcRepresent：DC voltage.
The active power of rectification side obtains two voltages by rectification side three-phase current and collector ring section mean value model before
It is calculated, obtained by the three-phase current of inverter side with inversion link mean value model before two of the active power of inverter side
Voltage is calculated, therefore can be obtained by the performance number on both sides.Further, since direct current transmission link be connected to rectification link with
Inversion link, capacitance voltage can not be mutated, then the DC voltage that its both sides obtains is necessarily consistent.At the same time, contrast is detailed
Thin model, it is also assumed that noenergy is lost, i.e. rectification side, the active power and the DC side of transverter that power network injects to transverter
Power is equal；Inverter side, DC side power are equal with the active power at the nearly user terminal of transverter, that is, the conservation of energy is determined
Rule application wherein, the DC current on both sides can be drawn by formula (2).The difference for the DC current that both sides are calculated is as direct current
The input of electric capacity, wherein DC capacitor occur in mean value model in the form of proportional component, the as 1/C in figure, finally
DC voltage is obtained by integral element.So far, the averaging model structure of direct current transmission link is completed.
Structure shown in Fig. 3, top half input is inverter side three-phase alternating current perunit value Iabc_grid_conv_pu,
Scaling be converted into after actual value of A phase currents therein is obtained into the average voltage Vab_gc phases of A, B two-phase voltage with step 2
The product multiplied subtracts scaling be converted into after actual value of C phase currents therein and obtains the average voltage of B, C two-phase voltage with step 2
The product of Vbc_gc multiplications, that is, obtain the exchange active-power P of inverter sideac, due to power-balance, by the exchange of obtained inverter side
Active-power PacDivided by DC voltage Vdc, then DC current Idc_gc corresponding to inverter side is obtained.The latter half input is rectification
Side three-phase alternating current perunit value Iabc_rotor_pu, it is converted into A phase currents therein are scaling after actual value and step
1 product for obtaining the average voltage Vab_rc multiplications of A, B two-phase voltage subtracts that C phase currents therein are scaling to be converted into actual value
The product that the average voltage Vbc_rc of B, C two-phase is multiplied is obtained with step 1 afterwards, that is, obtains the exchange active-power P of rectification sideac, by
In power-balance, by the exchange active-power P of obtained rectification sideacDivided by DC voltage Vdc, then obtain straight corresponding to rectification side
Flow electric current Idc_rc.Obtained DC current Idc_gc and DC current Idc_rc difference is subjected to PI regulations, you can obtain straight
Flow voltage Vdc(DC voltage V is obtained by direct current transmission Link Model i.e. described in steps 1 and 2dc)。
Step 4：The encapsulation of current transformer mean value model, can as shown in figure 4, three above link is uniformly encapsulated
To obtain integrating the mean value model of rectification, direct current transmission and inversion, that is, current transformer mean value model.By can be with figure
Find out, the mean value model there are 4 inputs, correspond to rectification, the input of three links of direct current transmission and inversion respectively, is respectively
Rectification side three-phase voltage and three-phase current and inverter side three-phase voltage and three-phase current.Meanwhile also have 5 output ports, respectively
It is the DC voltage that two voltages of rectification link output, two voltages of inversion link output and direct current transmission link obtain
Value, it is clear that also corresponding with the output of upper three links of figure.
In Fig. 4：
Uavg_grid_conv is represented：The three-phase alternating voltage perunit value that inverter side collects
Uavg_rotor_conv is represented：The three-phase alternating voltage perunit value that rectification side collects；
Iabc_grid_conv_pu is represented：Net side is the three-phase alternating current perunit value that inverter side collects；
Iabc_rotor_pu is represented：The three-phase alternating current perunit value that rectification side collects；
Vab_gc is represented：Step 2 obtains the average voltage level of A, B phase；
Vbc_gc is represented：Step 2 obtains the average voltage level of B, C phase；
Vab_rc is represented：Step 1 obtains the average voltage level of A, B phase；
Vbc_rc is represented：Step 1 obtains the average voltage level of B, C phase；
Vdc is represented：DC voltage.
So far, complete current transformer mean value model has successfully been built.
Rectification side and the output AC voltage output quantity of inversion side converter are line voltage, be connected respectively to two by
Voltage source is controlled (as shown in figure 5, rectification side is Vab_gc,Vbc_gc；Inverter side is two other), finally by the electricity of controlled voltage source
Pressure is transformed into current transformer three-phase alternating voltage, is connected to principal current other parts, it is possible to instead of the detailed unsteady flow based on IGBT
Device model.
In Fig. 5：
AC voltage source：Alternating-current voltage source；
Three-phase V-I measurement：Three-phase alternating voltage, current measurement rod；
Three-phase transformer：Three-phase transformer；
Three-phase serial RLC branch：Three phase of impedance；
Converter average model：Current transformer mean value model；
Uavg_grid_conv is represented：The three-phase alternating voltage perunit value that inverter side collects
Uavg_rotor_conv is represented：The three-phase alternating voltage perunit value that rectification side collects；
Iabc_grid_conv_pu is represented：Net side is the three-phase alternating current perunit value that inverter side collects；
Iabc_rotor_pu is represented：The three-phase alternating current perunit value that rectification side collects；
Vab_gc is represented：Step 2 obtains the average voltage level of A, B phase, is herein controlled source；
Vbc_gc is represented：Step 2 obtains the average voltage level of B, C phase, is herein controlled source；
Vab_rc is represented：Step 1 obtains the average voltage level of A, B phase, is herein controlled source；
Vbc_rc is represented：Step 1 obtains the average voltage level of B, C phase, is herein controlled source；
Vdc is represented：DC voltage.
Embodiment：
Application of the current transformer mean value model in VSC-HVDC system simulation models.
Fig. 5 is the VSC-HVDC system simulation models based on current transformer mean value model.The model left side is Wind turbines
Equivalent three phase mains, rectification side and inverter side use the mean value model of current transformer, and right side is power network.Whole wind-electricity integration system
System, its specific simulation parameter is as listed in table 1：
Table 1 simplifies system emulation parameter
Note：The specified apparent energy of P--；
Uf-- ac line voltage；
Udc-- DC voltages；
F-- mains frequencies；
L-- inductance values, R-- resistance, C-- electric capacity；
Simulation result is as shown in Figure of description, and wherein Fig. 6 is simplified model active power waveform, and Fig. 7 is conventional model
Active power waveform, Fig. 8 are simplified model DC voltage waveform, and Fig. 9 is conventional model DC voltage waveform.By using unsteady flow
Device mean value model replaces the scheme of detailed IGBT converter, and simplified model has been built on MatLab and has been emulated, according to
Simulation result, two models can be contrasted in terms of following two：(1) degree of accuracy, conventional model and simplified model are in rectification side, straight
The waveform and numerical value of three links of streaming and inverter side are veryed close；(2) efficiency, detailed transient state mistake is calculated due to no
Journey, all simplified model either topological structure or amount of calculation, far superior to original detailed model.
In order to verify the feasibility of simplified model, VSC-HVDC detailed models and simplified model are separately operable.Work out one
The individual program for calculating the time, the code of the program are as follows：
tic
sim('hvdc690_500_piungjun',[01])
Time_pingjun=toc
tic
sim('hvdc690_500_xiangxi',[01])
Time_xiangxi=toc,
So obtain the simulation time of two models in Matlab command windows.In based on Matlab analogue systems, in detail
The simulation run time of thin model is 29.0487s, and the simulation run time of simplified model is 18.3801s, it is seen then that simplifies mould
Type saves the nearly 10s times, and its amount of calculation is far smaller than detailed model, and simplified model operational efficiency is high.
Technical solution of the present invention by current transformer detailed model of the tradition based on IGBT by being replaced with the average mould of current transformer
Type, so as to enormously simplify the topological structure of VSC-HVDC total system models, simulation calculation amount greatly reduces.
The specific embodiment of the present invention is described above.It is to be appreciated that the invention is not limited in above-mentioned
Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow
Ring the substantive content of the present invention.
Claims (5)
1. a kind of modeling method suitable for VSC-HVDC systems, it is characterised in that comprise the following steps：
Step 1：Averagely simplify rectification link, the rectification Link Model after the averaged simplification of rectification link, be specially：
The input of rectification Link Model is the perunit value Uavg_rotor_conv of current transformer rectification side three-phase voltage reference signal,
By A, B two-phase therein and B, C two-phase perunit value by subtracting each other, two line voltages are obtained, then again with the two line electricity obtained
Pressure respectively with DC voltage VdcIt is multiplied, then two voltages by the acquisition that is multiplied are averaged to obtain average voltage Vab_ respectively
Avg and average voltage Vbc_avg；Finally by average voltage Vab_avg and average voltage Vbc_avg through amplitude limit (+Vdc,-Vdc) after
Exporting final magnitude of voltage is：The average voltage Vab_rc of A, B two-phase voltage exported after amplitude limit and exported after amplitude limit
B, C two-phase voltage average voltage Vbc_rc；
Step 2：Averagely simplify inversion link, the inversion Link Model after the averaged simplification of inversion link, be specially：
The input of inversion Link Model is the three-phase alternating voltage perunit value Uavg_grid_conv of current transformer inverter side, will wherein
A, B two-phase and B, C two-phase voltage perunit value by subtracting each other, two line voltages are obtained, then again with two line voltages obtained
With DC voltage VdcBe multiplied, then by be multiplied obtain two voltages be averaged respectively with obtain average voltage Vab_avg with
Average voltage Vbc_avg, current transformer real output value is converted to, most afterwards through amplitude limit (+Vdc,-Vdc) final magnitude of voltage is exported afterwards
For：The average voltage Vab_gc of A, B two-phase voltage exported after amplitude limit and B, C two-phase voltage for being exported after amplitude limit it is flat
Equal voltage Vbc_gc；
Step 3：Averagely simplify direct current transmission link, the direct current transmission Link Model connection after the averaged simplification of direct current transmission link
The rectification side and inverter side of current transformer, the input of direct current transmission Link Model is current transformer rectification side and the three-phase electricity of inverter side
Stream, respectively after scaling, passes through following two prime power formula and average voltage Vab_rc, average voltage Vbc_
Rc, average voltage Vab_gc, average voltage Vbc_gc are associated：
Pac=Vab·Ia-Vbc·Ic (1)
Pdc=Vdc·Idc (2)
Wherein, PacRepresent the exchange active power of input, VabThe average voltage Vab_rc and step 2 that expression step 1 obtains are obtained
Average voltage Vab_gc, IaRepresent the A phase currents collected, VbcRepresent the obtained average voltage Vbc_rc of step 1 and
The average voltage Vbc_gc, I that step 2 obtainscRepresent the C phase currents collected, PdcRepresent direct current active power, VdcRepresent direct current
Voltage, IdcDC current is represented, represents to be multiplied；
The step 3 is specially：
One input of direct current transmission Link Model is inverter side three-phase alternating current perunit value Iabc_grid_conv_pu, will
A phase currents therein are scaling to be converted into and obtains the average voltage Vab_gc of A, B two-phase voltage after actual value with step 2 and be multiplied
Product subtract scaling be converted into after actual value of C phase currents therein and obtain the average voltage of B, C two-phase voltage with step 2
The product of Vbc_gc multiplications, that is, obtain the exchange active-power P of inverter sideac, by the exchange active-power P of obtained inverter sideacRemove
With DC voltage Vdc, then DC current Idc_gc corresponding to inverter side is obtained.
2. the modeling method according to claim 1 suitable for VSC-HVDC systems, it is characterised in that
The step 3 is specially：
Another input of direct current transmission Link Model is rectification side three-phase alternating current perunit value Iabc_rotor_pu, by it
In A phase currents scaling be converted into the average voltage Vab_rc of A, B two-phase voltage obtained after actual value with step 1 be multiplied it
Product subtracts scaling be converted into after actual value of C phase currents therein and obtains the average voltage Vbc_rc phases of B, C two-phase with step 1
The product multiplied, that is, obtain the exchange active-power P of rectification sideac, by the exchange active-power P of obtained rectification sideacDivided by direct current
Press Vdc, then DC current Idc_rc corresponding to rectification side is obtained；
Obtained DC current Idc_gc and DC current Idc_rc difference is subjected to PI regulations, you can obtain DC voltage Vdc。
3. a kind of current transformer, it is characterised in that the equivalent model of the current transformer is to be applied to described in claim 1 or 2
The model that the modeling method of VSC-HVDC systems is established.
4. a kind of synchronous model machine, it is characterised in that including following device：
First device：For averagely simplifying rectification link；Rectification Link Model after the averaged simplification of rectification link, it is specially：
The input of rectification Link Model is the perunit value Uavg_rotor_conv of current transformer rectification side three-phase voltage reference signal,
By A, B two-phase therein and B, C two-phase perunit value by subtracting each other, two line voltages are obtained, then again with the two line electricity obtained
Pressure respectively with DC voltage VdcIt is multiplied, then two voltages by the acquisition that is multiplied are averaged to obtain average voltage Vab_ respectively
Avg and average voltage Vbc_avg；Finally by average voltage Vab_avg and average voltage Vbc_avg through amplitude limit (+Vdc,-Vdc) after
Exporting final magnitude of voltage is：The average voltage Vab_rc of A, B two-phase voltage exported after amplitude limit and exported after amplitude limit
B, C two-phase voltage average voltage Vbc_rc；
Second device, for averagely simplifying inversion link；Inversion Link Model after the averaged simplification of inversion link, it is specially：
The input of inversion Link Model is the three-phase alternating voltage perunit value Uavg_grid_conv of current transformer inverter side, will wherein
A, B two-phase and B, C two-phase voltage perunit value by subtracting each other, two line voltages are obtained, then again with two line voltages obtained
With DC voltage VdcBe multiplied, then by be multiplied obtain two voltages be averaged respectively with obtain average voltage Vab_avg with
Average voltage Vbc_avg, current transformer real output value is converted to, most afterwards through amplitude limit (+Vdc,-Vdc) final magnitude of voltage is exported afterwards
For：The average voltage Vab_gc of A, B two-phase voltage exported after amplitude limit and B, C two-phase voltage for being exported after amplitude limit it is flat
Equal voltage Vbc_gc；
3rd device, for averagely simplifying direct current transmission link；Direct current transmission link after the averaged simplification of direct current transmission link
Model is connected to the rectification side and inverter side of current transformer, and the input of direct current transmission Link Model is current transformer rectification side and inverter side
Three-phase current, respectively after scaling, by following two prime power formula and average voltage Vab_rc, average
Voltage Vbc_rc, average voltage Vab_gc, average voltage Vbc_gc are associated：
Pac=Vab·Ia-Vbc·Ic (1)
Pdc=Vdc·Idc (2)
Wherein, PacRepresent the exchange active power of input, VabRepresent the dresses of average voltage Vab_rc and second that first device obtains
Put obtained average voltage Vab_gc, IaRepresent the A phase currents collected, VbcRepresent the average voltage that first device obtains
The average voltage Vbc_gc, I that Vbc_rc and second device obtaincRepresent the C phase currents collected, PdcRepresent direct current wattful power
Rate, VdcRepresent DC voltage, IdcDC current is represented, represents to be multiplied；
Direct current transmission Link Model after the averaged simplification of direct current transmission link, it is specially：
One input of direct current transmission Link Model is inverter side three-phase alternating current perunit value Iabc_grid_conv_pu, will
Scaling be converted into after actual value of A phase currents therein obtains the average voltage Vab_gc of A, B two-phase voltage with second device
The product of multiplication subtracts scaling be converted into after actual value of C phase currents therein and obtains the flat of B, C two-phase voltage with second device
The product of equal voltage Vbc_gc multiplications, that is, obtain the exchange active-power P of inverter sideac, by the exchange wattful power of obtained inverter side
Rate PacDivided by DC voltage Vdc, then DC current Idc_gc corresponding to inverter side is obtained.
5. synchronous model machine according to claim 4, it is characterised in that the direct current after the averaged simplification of direct current transmission link passes
Defeated Link Model, it is specially：
Another input of direct current transmission Link Model is rectification side three-phase alternating current perunit value Iabc_rotor_pu, by it
In scaling be converted into after actual value of A phase currents obtain the average voltage Vab_rc phases of A, B two-phase voltage with first device
The product multiplied subtracts scaling be converted into after actual value of C phase currents therein and obtains the average voltage of B, C two-phase with first device
The product of Vbc_rc multiplications, that is, obtain the exchange active-power P of rectification sideac, by the exchange active-power P of obtained rectification sideacRemove
With DC voltage Vdc, then DC current Idc_rc corresponding to rectification side is obtained；
Obtained DC current Idc_gc and DC current Idc_rc difference is subjected to PI regulations, you can obtain DC voltage Vdc。
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|---|---|---|---|---|
| EP0056659B1 (en) * | 1981-01-21 | 1985-09-25 | Hitachi, Ltd. | Converter control apparatus for parallel connected multi-terminal direct current system |
| WO2006035018A2 (en) * | 2004-09-27 | 2006-04-06 | Areva T & D Uk Ltd | A direct current power transmission system and associated control method |
| CN103715716A (en) * | 2013-12-27 | 2014-04-09 | 上海交通大学 | Alternating current-direct current parallel system seamless switching control method based on VSC-HVDC |
| CN103840479A (en) * | 2013-12-16 | 2014-06-04 | 南方电网科学研究院有限责任公司 | Start control method for VSC-HVDC-based alternating current-direct current parallel system |
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2014
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0056659B1 (en) * | 1981-01-21 | 1985-09-25 | Hitachi, Ltd. | Converter control apparatus for parallel connected multi-terminal direct current system |
| WO2006035018A2 (en) * | 2004-09-27 | 2006-04-06 | Areva T & D Uk Ltd | A direct current power transmission system and associated control method |
| CN103840479A (en) * | 2013-12-16 | 2014-06-04 | 南方电网科学研究院有限责任公司 | Start control method for VSC-HVDC-based alternating current-direct current parallel system |
| CN103715716A (en) * | 2013-12-27 | 2014-04-09 | 上海交通大学 | Alternating current-direct current parallel system seamless switching control method based on VSC-HVDC |
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