CN105703387B - A kind of starting method of flexible HVDC transmission system - Google Patents
A kind of starting method of flexible HVDC transmission system Download PDFInfo
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- CN105703387B CN105703387B CN201410743481.5A CN201410743481A CN105703387B CN 105703387 B CN105703387 B CN 105703387B CN 201410743481 A CN201410743481 A CN 201410743481A CN 105703387 B CN105703387 B CN 105703387B
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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 present invention provides a kind of starting method of flexible HVDC transmission system, applied in the flexible HVDC transmission system including clamp Shuangzi module, in the first charging stage, the charging resistor access flexible HVDC transmission system including clamp Shuangzi module of the current transformer of power grid will be accessed, and carries out uncontrollable rectifier charging；In the second charging stage, open the guidance IGBT of the current transformer of access power grid, unlock the current transformer of rectification side, and unlock the current transformer of inverter side, the charging voltage of the inverter of clamp Shuangzi module is enabled to reach the charging voltage of the inverter of half-bridge module, dash current is big when to solve the problems, such as converter deblocking caused by the flexible HVDC transmission system charging voltage of C-MMC module is low, start the flexible HVDC transmission system by this method, either alternating current impact or DC current impact is all smaller.
Description
Technical field
The present invention relates to flexible transmission & distribution electro-technical fields, and in particular to one kind includes that clamp is double
The starting method of the flexible HVDC transmission system of submodule.
Background technique
Compared with the inverter of conventional voltage source, modularization multi-level converter (Modular Multilever
Converter, MMC) have many advantages, such as that favorable expandability, harmonic wave are small, switching frequency is low, few to the consistent triggering requirement of device, especially
Suitable for direct current transportation application.
To reduce loss and number of devices, the MMC of early stage uses half-bridge sub-module cascade form, but half-bridge sub-module cascade
The MMC of form can not effectively be latched DC Line Fault, therefore, based on clamp Shuangzi module (Clamp Double Submodule,
CDSM modified MMC (referred to as C-MMC)) obtains more and more pro-gazes.The topological structure of the C-MMC module is early in addition to retaining
Outside the general advantage of phase MMC, maximum advantage, which is quickly to control using inverter, realizes DC Line Fault self-cleaning, and volume
Outer increased device and loss are little.Therefore, the flexible HVDC transmission system including C-MMC has broad application prospects.
Uncontrollable rectifier charging is carried out when the existing flexible HVDC transmission system starting including C-MMC, the C-MMC module
Topological structure causes flexible HVDC transmission system in uncontrollable rectifier charging, and d-c bus voltage value is lower, far below specified
DC bus-bar voltage when work.In this case if directly unlocking inverter, biggish dash current can be generated.
To solve the above-mentioned problems, the serial connection charge resistance usually in flexible HVDC transmission system charges to bus in uncontrollable rectifier
After voltage rises towards rated value, then cut off charging resistor.However, although the method by serial connection charge resistance can reduce
Dash current, but additional power loss is also brought, meanwhile, it also has a certain impact to the cooling requirements of charging resistor.
Therefore, a kind of starting scheme applied in the flexible HVDC transmission system including clamp Shuangzi module is needed, with
Solve above-mentioned technical problem.
Summary of the invention
The present invention aiming at the above shortcomings existing in the prior art, provides a kind of starting side of flexible HVDC transmission system
When method to solve includes converter deblocking in the flexible HVDC transmission system for clamp Shuangzi module the dash current that generates compared with
Greatly, additional power loss is led to the problem of.
The present invention is in order to solve the above technical problems, adopt the following technical scheme that
The present invention provides a kind of starting method of flexible HVDC transmission system, applied to the flexibility for including clamp Shuangzi module
In DC transmission system, the method successively includes the first charging stage and the second charging stage；
Following steps are executed in the first charging stage:
The charging resistor access flexible DC transmission system including clamp Shuangzi module of the current transformer of power grid will be accessed
System, and carry out uncontrollable rectifier charging；
Following steps are executed in the second charging stage:
Open the guidance insulated gate bipolar transistor IGBT of the current transformer of access power grid；
Unlock the current transformer of rectification side；
Unlock the current transformer of inverter side.
Preferably, the guidance insulated gate bipolar transistor IGBT of the current transformer for opening access power grid specifically includes:
Divide and once opens or divide the guidance IGBT for opening the current transformer of access power grid at least twice.
Preferably, if dividing the guidance IGBT for opening the current transformer of access power grid at least twice, different number is opened every time
Guide IGBT.
Preferably, the guidance insulated gate bipolar transistor IGBT of the current transformer for opening access power grid specifically includes:
Open the whole guidance IGBT or part guidance IGBT of the current transformer of access power grid.
Preferably, if opening the part guidance IGBT of the current transformer of access power grid, the current transformer of access power grid is opened
The minimum number of guidance IGBT can determine by the following method:
DC bus electricity according to the dash current maximum value of other IGBT in unlock clamp Shuangzi module, before determining unlock
Pressure value；Wherein, other IGBT refer in the clamp Shuangzi module, clamp the IGBT in Shuangzi module in addition to guiding IGBT；
According to the d-c bus voltage value before the unlock determined, the charging voltage value after uncontrollable rectifier charging and every
The value added of DC bus charging voltage, calculates the minimum number for opening guidance IGBT when opening a guidance IGBT.
Further, it includes the soft of clamp Shuangzi module that the charging resistor access of the current transformer that will access power grid is described
Property DC transmission system before, the method also includes: connection DC bus；
The progress uncontrollable rectifier charging, specifically includes:
Current transformer is accessed into power grid, and carries out uncontrollable rectifier by the charging resistor of the current transformer of the access power grid and fills
Electricity.
Further, before the guidance insulated gate bipolar transistor IGBT of the current transformer for opening access power grid,
Further include: the charging resistor of the current transformer of excision access power grid.
Preferably, when the flexible HVDC transmission system including clamp Shuangzi module is single ended active flexible DC transmission
When double ended system,
It is described to specifically include current transformer access power grid: the current transformer of rectification side is accessed into power grid；
The charging resistor of the current transformer of the excision access power grid, specifically includes: cutting off the charging of the current transformer of rectification side
Resistance；
After the current transformer of the unlock inverter side, the method also includes: cut off the charging of the current transformer of inverter side
Resistance.
Preferably, when the flexible HVDC transmission system including clamp Shuangzi module is single ended active flexible DC transmission
When double ended system, before the current transformer of the unlock inverter side, the method also includes:
The quantity of capacitor in the clamp Shuangzi module of the current transformer of inverter side is gradually reduced into half, wherein every to reduce one
After secondary capacitor quantity, according to capacitor voltage equalizing strategy, each clamp Shuangzi module rotation incision in the current transformer is controlled.
Preferably, when the flexible HVDC transmission system including clamp Shuangzi module is double-end active flexible DC transmission
When double ended system,
It is described to specifically include current transformer access power grid: the current transformer of rectification side and the current transformer of inverter side are accessed into electricity
Net；
The charging resistor of the current transformer of the excision access power grid, specifically includes: cutting off the charging of the current transformer of rectification side
The charging resistor of resistance and the current transformer of inverter side.
The present invention is by opening the current transformer of access power grid after uncontrollable rectifier charging complete, before unlock inverter
IGBT is guided, the charging voltage of the inverter of clamp Shuangzi module is enabled to reach the charging electricity of the inverter of half-bridge module
Pressure, thus dash current when converter deblocking caused by the flexible HVDC transmission system charging voltage for solving C-MMC module is low
Big problem starts the flexible HVDC transmission system, either alternating current impact or DC current punching by this method
It hits all smaller；In addition, by before opening the guidance IGBT of current transformer of access power grid, the current transformer of excision access power grid
Charging resistor will not generate additional power loss to avoid introducing charging resistor when opening guidance IGBT charging.
Detailed description of the invention
Fig. 1 is the topological diagram for clamping Shuangzi module；
Fig. 2 inactive guidance IGBT (T when being clamp Shuangzi module charging5) current path schematic diagram；
Fig. 3 is current path schematic diagram when half-bridge module charges；
Fig. 4 is to clamp the current path schematic diagram that guidance IGBT is opened when the charging of Shuangzi module；
Fig. 5 is the single ended active flexible DC transmission double ended system schematic diagram for including clamp Shuangzi module；
Fig. 6 is the double-end active flexible DC transmission double ended system schematic diagram for including clamp Shuangzi module.
Specific embodiment
The present invention is by rationally using the guidance IGBT in clamp Shuangzi module, making to clamp not controlling for Shuangzi module (CDSM)
Rectification charging characteristic is identical as the uncontrollable rectifier charge characteristic of half-bridge module (HBSM), so as to reach higher DC bus
Voltage, the greater impact electric current generated when reducing converter deblocking, will not generate additional power loss.
Below in conjunction with the attached drawing in the present invention, clear, complete description is carried out to the technical solution in the present invention, is shown
So, described embodiment is a part of the embodiments of the present invention, instead of all the embodiments.Based on the implementation in the present invention
Example, those of ordinary skill in the art's every other embodiment obtained without making creative work, all belongs to
In the scope of protection of the invention.
It is described in detail below in conjunction with pair the principle of the present invention of Fig. 1,2,3,4.
Referring to Fig. 1, clamp Shuangzi module include: 5 IGBT (Insulated Gate Bipolar Trans istor,
Guide insulated gate bipolar transistor): T11、T12、T21、T22、T5, 2 capacitors: C1And C2And 7 diodes: D11、D12、
D21、D22、D5、D31、D32, wherein T5To guide IGBT, D5For T5Anti-paralleled diode, D31And D32For clamp diode, T5、
D5、D31And D32Clamp Shuangzi module is divided into two groups.In the first set, D11For T11Anti-paralleled diode, T11Emitter connect
Meet the interface A, T of clamp Shuangzi module11Collector connect capacitor C1With clamp diode D31Cathode；D12For T12It is anti-simultaneously
Union II pole pipe, T12Collector connection clamp Shuangzi module interface A, T12Emitter connection guidance IGBT (T5) transmitting
Pole, clamp diode D32Cathode, D12Anode and capacitor C1.In the second set, D22For T22Anti-paralleled diode, T22's
The interface B, T of emitter connection clamp Shuangzi module22Collector connection guidance IGBT (T5) collector, capacitor C2And clamp
Diode D31Anode；D21For T21Anti-paralleled diode, T21Collector connection clamp Shuangzi module interface B, T21's
Emitter connects clamp diode D32Anode, D21Anode and capacitor C2。
Fig. 2 inactive guidance IGBT (T when being clamp Shuangzi module charging5) current path schematic diagram, as shown in Fig. 2,
A, B, C three-phase include upper bridge arm and lower bridge arm, and n clamp Shuangzi module (CDSM) is connected in series in the upper and lower bridge arm of every phase,
The modular structure of each clamp Shuangzi module (CDSM) is all made of topological structure shown in FIG. 1.Below in bridge arm in A phase
For one clamp Shuangzi module, when illustrating to clamp the charging of Shuangzi module in the second charging stage, in inactive guidance IGBT
(T5) in the case of, AB alternate current path.
Two-way dotted arrow in Fig. 2 respectively represents two current paths, and current path 1 is indicated by B phase flow direction A phase, tool
Body are as follows: electric current is flowed out from B phase, the D successively clamped in Shuangzi module via A phase first11、C1、D5、T21、D21, flow to subsequent string
Other clamp Shuangzi modules of connection, finally flow to A phase.Current path 2 indicates by A phase flow direction B phase, specifically: electric current is flowed from A phase
Enter, flows to first clamp Shuangzi module of A phase via other concatenated clamp Shuangzi modules, successively clamped via A phase first
D in Shuangzi module22、D31-C1And C2-D32、D12, flow to concatenated n clamp Shuangzi module in B phase.
Two capacitor C when electric current is flowed according to current path 1, in the clamp Shuangzi module1And C2For series relationship,
It seals in circuit and charges jointly；Two capacitor C when electric current is flowed according to current path 2, in the clamp Shuangzi module1
And C2For parallel relationship, it is incorporated in circuit and charges jointly.
When electric current is flowed according to current path 1, the clamp of bridge arm is double in the clamp Shuangzi module and B phase of bridge arm in A phase
Submodule is in different states: it is electric current inflow for the clamp Shuangzi module of bridge arm in A phase, and for bridge in B phase
The clamp Shuangzi module of arm is electric current outflow, therefore, two capacitor C of the clamp Shuangzi module of bridge arm in A phase1And C2Series connection
Enter circuit, and two capacitor parallel connections of the clamp Shuangzi module of bridge arm access circuit in B phase.When electric current is flowed according to current path 2
When dynamic, two capacitor C of the clamp Shuangzi module of bridge arm in A phase1And C2Parallel connection access circuit, and in B phase bridge arm clamp Shuangzi
Two capacitor C of module1And C2Series connection access circuit.
Fig. 3 be half-bridge module charge when current path schematic diagram, as shown in figure 3, A, B, C three-phase include upper bridge arm and
Lower bridge arm, upper and lower bridge arm are connected in series 2n half-bridge module (HBSM), and the topological structure of each half-bridge module (HBSM) is Fig. 1
Shown in clamp Shuangzi module (CDSM) topological structure half, that is to say, that the series connection of two half-bridge modules (HBSM) is suitable
In 1 clamp Shuangzi module (CDSM).Below by taking first half-bridge module in A phase in bridge arm as an example, illustrate in the second charging
When half-bridge module charges in stage, A, B alternate current path.
Two-way dotted arrow in Fig. 3 respectively represents two current paths, and current path 1 is indicated by B phase flow direction A phase, tool
Body are as follows: electric current is flowed out from B phase, successively via the D in first half-bridge module of A phase11And C1, flow to other subsequent concatenated half-bridges
Module finally flow to A phase.Current path 2 indicates by A phase flow direction B phase, specifically: electric current is flowed into from A phase, via it is concatenated its
His half-bridge module flows to first half-bridge module of A phase, via the D in first half-bridge module of A phase12Flow to concatenated 2n in B phase
A half-bridge module.
Analysis according to front to Fig. 2, to half-bridge module shown in Fig. 3 it can be concluded that when electric current is according to electricity
When flow path 1 flows, the capacitor C of the clamp Shuangzi module of bridge arm in A phase1Access circuit, and in B phase bridge arm clamp Shuangzi mould
The capacitor of block is cut off from circuit.When electric current is flowed according to current path 2, the capacitor of the clamp Shuangzi module of bridge arm in A phase
C1It is cut off from circuit, the capacitor of the clamp Shuangzi module of the upper bridge arm of B accesses circuit.
Therefore, for the clamp Shuangzi Flexible module DC transmission system and half-bridge module flexible direct current of identical voltage class
For transmission system, when uncontrollable rectifier charges, concatenated capacitor quantity is different in AB circuitry phase, for example, double in clamp
In the AB circuitry phase of submodule flexible HVDC transmission system, concatenated capacitor is 2.5n, and defeated in half-bridge module flexible direct current
In the AB circuitry phase of electric system, concatenated capacitor is 2n, it is seen then that the concatenated capacitor quantity of circuit is than half in clamp Shuangzi module
The concatenated capacitor quantity of circuit is more in bridge module, and therefore, the charging voltage for clamping each capacitor in Shuangzi module is lower than half-bridge mould
The charging voltage of each capacitor in block.
Comparison diagram 2 and Fig. 3 can be seen that for the single clamp Shuangzi module of bridge arm in A phase and half-bridge module, electricity
Stream flows (flowing from above to below) according to current path 1 and is consistent, and electric current flow according to current path 2 (i.e. from lower and
Upper flowing) it is inconsistent.
Due in normal work, clamping the guidance IGBT (T of Shuangzi module5) in opening state, and inventors have found that
Open guidance IGBT (T5) after, it clamps uniform when Shuangzi module and half-bridge module are flowed according to current path 1 and current path 2
It causes.That is, clamp Shuangzi module is filled if opening guidance IGBT in the charging process before unlocking inverter
Electric principle and the charging principle of half-bridge module should be identical.Therefore, in this case, the charging electricity of Shuangzi module is clamped
Pressure should be consistent with the charging voltage of half-bridge module, thus, it is possible to which solving includes the flexible DC transmission system for clamping Shuangzi module
Dash current big problem when converter deblocking caused by charging voltage of uniting is low.
Below in conjunction with Fig. 4, guidance IGBT (T is opened when to clamp Shuangzi module charging5) current path carry out analysis and say
It is bright.As shown in figure 4, in clamp Shuangzi module charging process, if opening guidance IGBT (T5), then when electric current is according to electric current
When path 1 is flowed, electric current is flowed out from B phase, successively via the D in first diode clamp module of A phase11、C1、D5、C2、D21,
Other subsequent concatenated diode clamp modules are flowed to, A phase is finally flow to, that is to say, that the clamp Shuangzi module of bridge arm in A phase
Two capacitor C1And C2All series connection access circuit charges, and two capacitors of the clamp Shuangzi module of bridge arm are from circuit in B phase
Excision.When electric current is flowed according to current path 2, electric current is flowed into from A phase, is flowed to via other concatenated diode clamp modules
First diode clamp module of A phase, successively via the D in first diode clamp module of A phase22、T5、D12, flow in B phase
Concatenated n diode clamp module, that is to say, that two capacitor C of the clamp Shuangzi module of bridge arm in A phase1And C2From circuit
Middle excision, two capacitors of the clamp Shuangzi module of bridge arm all series connection access circuit chargings in B phase.As can be seen that shown in Fig. 4
Clamp Shuangzi module charging when open guidance IGBT (T5) current path and half-bridge module shown in Fig. 3 charge when electric current
Path (including current path 1 and current path 2) is identical.
It should be noted that clamp Shuangzi module has DC Line Fault processing function, that is to say, that when generation DC Line Fault
When, the flexible HVDC transmission system including clamping Shuangzi module can utilize pincers with the trigger signal of all IGBT of quick lock
The reverse blocking capability of back-emf and diode that position Shuangzi module capacitance provides quickly completes latching process, is not necessarily to alternating current interruption
Device movement.Therefore, it is necessary to can just open guidance IGBT in the case where no DC Line Fault.
The present invention provides a kind of starting method of flexible HVDC transmission system as a result, is applied to include clamp Shuangzi module
Flexible HVDC transmission system in.Flexible HVDC transmission system including clamping Shuangzi module may include the current transformer of rectification side
With the current transformer of inverter side, the current transformer of rectification side and the current transformer of inverter side are all made of clamp Shuangzi module reality shown in Fig. 4
It is existing.The current transformer work of rectification side controls DC bus-bar voltage in rectification state, and the current transformer of inverter side works in inversion shape
State controls active and reactive power transmission.The current transformer of rectification side is connected with the current transformer of inverter side via DC bus, and
The current transformer of rectification side and the current transformer of inverter side are separately connected charging resistor.It is soft in the single ended active including clamp Shuangzi module
In property direct current transportation double ended system (hereinafter referred to as single ended active double ended system), the current transformer of rectification side via rectification side unsteady flow
The charging resistor of device, transformer and alternating current circuit impedance access power grid 1, the current transformer of inverter side via inverter side current transformer
Charging resistor, transformer connect wind power plant or passive load with alternating current circuit impedance.It is including that the both-end for clamping Shuangzi module has
In source flexible DC transmission double ended system (hereinafter referred to as double-end active double ended system), the current transformer of rectification side is via rectification side
The charging resistor of current transformer, transformer and alternating current circuit impedance access power grid 1, the current transformer of inverter side via inverter side unsteady flow
Charging resistor, transformer and the alternating current circuit impedance of device access power grid 2.
The starting method of the flexible HVDC transmission system including clamp Shuangzi module successively included: the first charging stage
With the second charging stage.
It, can be according to the starting of the existing flexible HVDC transmission system including clamp Shuangzi module in the first charging stage
Method is operated, i.e. execution following steps:
Step 101, it is connected to DC bus.
The step is to start the flexible HVDC transmission system including clamp Shuangzi module and preparing, specifically, closure is whole
The dc switch between the current transformer of side and the current transformer of inverter side is flowed, to be connected to the current transformer of rectification side and the unsteady flow of inverter side
DC bus between device.Before the current transformer of current transformer and inverter side to rectification side charges, Shuangzi module is clamped
Undertension to drive IGBT, therefore, the current transformer of rectification side and the current transformer of inverter side are in blocking.
Step 102, the charging resistor access flexibility including clamp Shuangzi module that will access the current transformer of power grid is straight
Flow transmission system.
It should be noted that needing to access described in the charging resistor access of the current transformer of power grid in the first charging stage
Including clamp Shuangzi module flexible HVDC transmission system, in this way can using charging resistor be access power grid current transformer into
The charging of row uncontrollable rectifier.That is, the charging resistor of the current transformer of rectification side is connect for single ended active double ended system
Enter the single ended active system, it is preferred that it is double the charging resistor of the current transformer of inverter side can also to be accessed into the single ended active
End system.For double-end active double ended system, by the current transformer of the charging resistor of the current transformer of rectification side and inverter side
Charging resistor accesses the double-end active double ended system.
Step 103, current transformer is accessed into power grid, and carries out uncontrollable rectifier by the charging resistor of the current transformer of access power grid
Charging.
Specifically, in the single ended active flexible DC transmission double ended system for including clamp Shuangzi module, by rectification side
Current transformer accesses power grid 1, and carries out uncontrollable rectifier charging by the charging resistor of the current transformer of rectification side；It is including clamp Shuangzi
In the double-end active flexible DC transmission double ended system of module, the current transformer of rectification side is accessed into power grid 1, and by the change of inverter side
It flows device and accesses power grid 2, and carried out not by the charging resistor of the current transformer of the charging resistor and inverter side of the current transformer of rectification side
Control rectification charging.
In the second charging stage, following steps can be executed:
Step 201, the guidance IGBT of the current transformer of access power grid is opened.
Specifically, being charged by opening guidance IGBT to the current transformer of access power grid in the second charging stage.Unsteady flow
The guidance IGBT of device is T5, in single ended active double ended system, the current transformer for accessing power grid is the current transformer of rectification side, in both-end
In active double ended system, the current transformer for accessing power grid is the current transformer of rectification side and the current transformer of inverter side.Open guidance IGBT
Specific implementation be described in detail again subsequent.
Step 202, the current transformer of rectification side is unlocked.
Specifically, when the first charging stage carrying out uncontrollable rectifier charging, the current transformer of rectification side and the unsteady flow of inverter side
Device is in blocking.In the second charging stage, the current transformer of access power grid is carried out in charging process, the unsteady flow of rectification side
Device and the current transformer of inverter side are also at blocking, have opened in the guidance IGBT for the unsteady flow for needing the access power grid opened
Finish, and DC bus-bar voltage is stable and then the current transformer of unlock rectification side, specifically, can by setting delay time come
The unlock time started of the current transformer of rectification side is controlled, to ensure that DC bus has time enough that can reach stable.
Step 203, the current transformer of inverter side is unlocked.
After DC bus-bar voltage is promoted and stablized, the current transformer of inverter side is unlocked.Specifically, can be by judging direct current mother
Whether the detected value of line voltage and the difference of instruction value are less than preset threshold value to determine whether current DC bus-bar voltage has been promoted
Stablize, stablizes once judging that DC bus-bar voltage is promoted, then can unlock the current transformer of inverter side.
The mode of unlock current transformer belongs to the prior art, and details are not described herein.
Preferably, in single ended active double ended system, in order to which the dash current control that the current transformer of inverter side generates will be unlocked
System in minimum, unlock inverter side current transformer (i.e. before step 203), following steps can also be performed:
The quantity of capacitor in the clamp Shuangzi module of the current transformer of inverter side is gradually reduced into half, wherein every to reduce one
After secondary capacitor quantity, according to capacitor voltage equalizing strategy, each clamp Shuangzi module rotation incision in the current transformer of inverter side is controlled.?
That is capacitor quantity is subtracted from 2n for a clamp Shuangzi module in one bridge arm of current transformer of inverter side
As little as n, the mode for reducing capacitor quantity is unlimited, for example, can reduce according to arithmetic progression, the capacitor quantity of each reduction
It is unlimited.
It preferably, can be in uncontrollable rectifier charging complete (i.e. first in order to further avoid generating additional power loss
Charging stage terminates) after, in the second charging stage excision access power grid current transformer charging resistor, i.e., step 201 it
Before, execute following steps:
Step 200, the charging resistor of the current transformer of excision access power grid.
Specifically, the charging resistor of the current transformer of rectification side is cut off in single ended active double ended system, it is double in double-end active
In end system, the charging resistor of the charging resistor of the current transformer of rectification side and the current transformer of inverter side is cut off.That is,
In two charging stages, the charging resistor of current transformer is not accessed in the flexible HVDC transmission system including clamping Shuangzi module, this
Sample would not also have the power loss generated by charging resistor.
It should be noted that in single ended active double ended system, unlock inverter side current transformer (i.e. step 203) it
Afterwards, the method can also include: to cut off the charging resistor of the current transformer of inverter side.Specifically, being first closed the unsteady flow of inverter side
The alternating-current switch of device, to provide stable alternating voltage to wind power plant or passive load, to dash current after, then cut off
The charging resistor of the current transformer of inverter side.
After above-mentioned steps are finished, inverter side power ascension to target value, described includes the flexibility of clamp Shuangzi module
The start-up course of DC transmission system terminates, and described includes that the flexible HVDC transmission system of clamp Shuangzi module enters steady-state operation
Stage.
The specific implementation of the split guidance IGBT for connecting the current transformer into power grid is described in detail below.
The guidance IGBT for accessing the current transformer of power grid, which can divide, once to be opened or point open-minded at least twice, if being divided at least two
It is secondary open-minded, the guidance IGBT of identical quantity can be opened every time, such as open guidance IGBT one by one, i.e., once open one
IGBT can also open the guidance IGBT of different number every time.The guidance IGBT for accessing the current transformer of power grid can be all open-minded
Can also part it is open-minded.
It usually, can be according to the requirement to the flexible HVDC transmission system for including clamp Shuangzi module and including pincers
The actual conditions of the flexible HVDC transmission system of position Shuangzi module select the optimal guidance IGBT to open mode, that is to say, that
The guidance IGBT which kind of is selected optimal opens mode depending on the adaptation of requirement and system to dash current to the charging time
Ability.If the flexible HVDC transmission system for requiring to include clamp Shuangzi module has the shorter charging time, preferably adopt
With disposably open all guidance IGBT modes, or using repeatedly open part guide IGBT by the way of, open every time compared with
The guidance IGBT of multi-quantity.If of less demanding to the charging time for the flexible HVDC transmission system for including clamp Shuangzi module,
And the ability to bear of the dash current of the flexible HVDC transmission system including clamping Shuangzi module is poor, then preferably uses and open one by one
The mode of logical guidance IGBT, such as it is divided into that n times are open-minded, the quantity that 1 guidance IGBT, n are clamp Shuangzi module is opened every time.
If the guidance IGBT of the current transformer of access power grid is opened in part, in order to make other IGBT in unlock clamp Shuangzi module
When the dash current that generates be less than the dash current maximum value of other IGBT in unlock clamp Shuangzi module, it is necessary to open a fixed number
The guidance IGBT of amount, then the minimum number N for the guidance IGBT for needing to open0It can determine in the following manner:
Firstly, according to the dash current maximum value ireq of other IGBT in unlock clamp Shuangzi module, before determining unlock
D-c bus voltage value Utarget.Wherein, the dash current maximum value ireq of other IGBT is to set in unlock clamp Shuangzi module
Definite value.
It is rushed specifically, the d-c bus voltage value Utarget and unlock before unlock clamp other IGBT in Shuangzi module
Current maxima ireq is hit in functional relation, i.e. Utarget=f (ireq), the DC bus-bar voltage Utarget before unlock are solutions
The function of the dash current maximum value ireq of other IGBT, the two meet inversely prroportional relationship in lock clamp Shuangzi module, that is,
It says, the ability of the shock resistance electric current of the flexible HVDC transmission system including clamping Shuangzi module is bigger, d-c bus voltage value
Utarget can be lower, and vice versa.
Secondly, filling after being charged according to d-c bus voltage value Utarget, the uncontrollable rectifier before the unlock determined
Piezoelectric voltage value Uorg and often open one guidance IGBT when DC bus charging voltage value added Δ U, calculating open guidance
The minimum number N of IGBT0。
Specifically, opening the minimum number N of guidance IGBT0It can be calculated by the following formula to obtain: N0=(Utarget-
Uorg)/ΔU；
Wherein, Uorg can be uniquely determined according to the topological structure and system alternating voltage of clamp Shuangzi module；Δ U can be with
The quantity of Shuangzi module is clamped only according in the current transformer of clamp Shuangzi module topology structure, system alternating voltage and access power grid
One determines.
The present invention is by opening the current transformer of access power grid after uncontrollable rectifier charging complete, before unlock inverter
IGBT is guided, the charging voltage of the inverter of clamp Shuangzi module is enabled to reach the charging electricity of the inverter of half-bridge module
Pressure, thus dash current when converter deblocking caused by the flexible HVDC transmission system charging voltage for solving C-MMC module is low
Big problem starts the flexible HVDC transmission system, either alternating current impact or DC current punching by this method
It hits all smaller.The present invention selects the opportunity for opening guidance IGBT, will not introduce volume merely with the working characteristics of clamp Shuangzi module
Outer power loss has more superiority.
In order to clearly illustrate technical solution of the present invention, below in conjunction with Fig. 5 and Fig. 6, respectively to include clamp Shuangzi
The single ended active flexible DC transmission double ended system of module and the double-end active flexible DC transmission including clamping Shuangzi module are double
For end system, the starting method of flexible HVDC transmission system is described in detail.
Fig. 5 is the single ended active flexible DC transmission double ended system schematic diagram for including clamp Shuangzi module, as shown in figure 5,
The system includes two C-MMC, wherein the C-MMC in left side works in rectification state, for controlling DC bus-bar voltage, referred to as
The current transformer of rectification side；The current transformer work on right side is in inverter mode, for controlling active and reactive power transmission, referred to as
The current transformer of inverter side.The three-phase of three-phase AC grid 1 is connect with alternating current circuit impedance, and alternating current circuit impedance connects transformer 1,
1 connected AC switch S1 of transformer, the charging resistor and resistance by-pass switch of the current transformer of alternating-current switch S1 connection rectifier side
S2, wherein resistance by-pass switch S2 is in parallel with the charging resistor of the current transformer of the rectifier side, connects the unsteady flow of rectification side later
Device.The current transformer of rectification side is connected with the current transformer of inverter side by DC bus, and dc switch K1 is provided on DC bus
And K2, dc switch K1 and K2 are connected to for controlling DC bus.The change of the output end connection inverter side of the current transformer of inverter side
Flow the charging resistor and resistance by-pass switch S4 of device, wherein the charging resistor of resistance by-pass switch S4 and the current transformer of inverter side
Parallel connection, connected AC switch S3, the output end of S3 connection transformer 2, transformer 2 connect alternating current circuit impedance, pass through friendship later
Flow Line impedance finally connects wind power plant or passive load.
Shown in fig. 5 includes that the starting method of the single ended active flexible DC transmission double ended system of clamp Shuangzi module includes
First charging stage and the second charging stage.
Following steps are executed in the first charging stage:
Step 501, it is closed dc switch K1 and K2, and the current transformer of rectification side and the current transformer holding of inverter side is kept to close
Lock.At this point, alternating-current switch S1 and S3 and resistance by-pass switch S2 and S4 are disconnected.
Step 502, it is closed alternating-current switch S1, the current transformer of rectification side is accessed power grid 1, so as to the change to rectification side
It flows device and carries out uncontrollable rectifier charging.
Specifically, keep resistance by-pass switch S2 to disconnect during uncontrollable rectifier charging, thus the current transformer of rectification side
The described charging resistor access includes the single ended active flexible DC transmission double ended system for clamping Shuangzi module, to carry out uncontrollable rectifier
Charging.
It should be noted that the dash current generated when in order to limit uncontrollable rectifier, in step 502, alternating-current switch S3
It is remained open with resistance by-pass switch S4.
After uncontrollable rectifier charging complete, i.e. the first charging stage, into the second charging stage, in the second charging rank
Duan Zhihang following steps:
Step 503, closed resistance by-pass switch S2, to cut off the charging resistor of the current transformer of rectification side.
Step 504, the guidance IGBT of the current transformer of rectification side is opened.
Specifically, guidance IGBT is opened there are many modes, such as it can divide and once to open or point open-minded at least twice,
Guidance IGBT can be opened one by one, and perhaps each guidance IGBT for opening different number can open all guidance IGBT or open
Logical part guidance IGBT.It can be according to the requirement to the single ended active flexible DC transmission double ended system for including clamp Shuangzi module
And the actual conditions of the single ended active flexible DC transmission double ended system including clamping Shuangzi module select optimal guidance
IGBT opens mode, and specific implementation is as previously mentioned, details are not described herein.
Step 505, the guidance IGBT for needing to open open finish and DC bus stablize after, unlock the unsteady flow of rectification side
Device.
Step 506, the quantity of capacitor in the clamp Shuangzi module of the current transformer of inverter side is gradually reduced into half, wherein
After capacitor quantity of every reduction, according to capacitor voltage equalizing strategy, each clamp Shuangzi module wheel in the current transformer of inverter side is controlled
Change incision.
Step 507, after DC bus-bar voltage promotion is stablized, the current transformer of inverter side is unlocked.
Step 508, it is closed alternating-current switch S3, after dash current, closed resistance by-pass switch S4 is inverse to cut off
Become the charging resistor of the current transformer of side.
It should include the single ended active flexible DC transmission both-end of clamp Shuangzi module after inverter side power ascension to target value
The start-up course of system terminates, into steady state operation phase.
Fig. 6 is the double-end active flexible DC transmission double ended system schematic diagram for including clamp Shuangzi module, as shown in fig. 6,
The system includes two C-MMC, wherein the C-MMC in left side works in rectification state, for controlling DC bus-bar voltage, referred to as
The current transformer of rectification side；The current transformer work on right side is in inverter mode, for controlling active and reactive power transmission, referred to as
The current transformer of inverter side.The three-phase of three-phase AC grid 1 is connect with alternating current circuit impedance, and alternating current circuit impedance connects transformer 1,
1 connected AC switch S1 of transformer, the charging resistor and resistance by-pass switch of the current transformer of alternating-current switch S1 connection rectifier side
S2, wherein resistance by-pass switch S2 is in parallel with the charging resistor of the current transformer of the rectifier side, connects the unsteady flow of rectification side later
Device.The current transformer of rectification side is connected with the current transformer of inverter side by DC bus, and dc switch K1 is provided on DC bus
And K2, dc switch K1 and K2 are connected to for controlling DC bus.The change of the output end connection inverter side of the current transformer of inverter side
Flow the charging resistor and resistance by-pass switch S4 of device, wherein the charging resistor of resistance by-pass switch S4 and the current transformer of inverter side
Parallel connection, connected AC switch S3, the output end of S3 connection transformer 2, transformer 2 connect alternating current circuit impedance, pass through friendship later
Flow Line impedance finally connects AC network 2.
Shown in fig. 6 includes that the starting method of the double-end active flexible DC transmission double ended system of clamp Shuangzi module includes
First charging stage and the second charging stage.
Following steps are executed in the first charging stage:
Step 601, it is closed dc switch K1 and K2, and the current transformer of rectification side and the current transformer holding of inverter side is kept to close
Lock.At this point, alternating-current switch S1 and S3 and resistance by-pass switch S2 and S4 are disconnected.
Step 602, it is closed alternating-current switch S1, the current transformer of rectification side is accessed power grid 1, so as to the change to rectification side
It flows device and carries out uncontrollable rectifier charging.After uncontrollable rectifier charging complete, it is closed alternating-current switch S3, the current transformer of inverter side is accessed into electricity
Net 2.
Specifically, keeping resistance by-pass switch S2 and S4 to disconnect, thus the unsteady flow of rectification side during uncontrollable rectifier charging
The described charging resistor access of the current transformer of the charging resistor and inverter side of device includes the double-end active flexibility for clamping Shuangzi module
Direct current transportation double ended system, to carry out uncontrollable rectifier charging.
It should be noted that alternating-current switch S1 and S3 can also be closed at, that is, it is performed simultaneously following operation: by rectification side
Current transformer access power grid 1, and the current transformer of inverter side is accessed into power grid 2.
After the current transformer of uncontrollable rectifier charging complete and rectification side accesses power grid 1 and the current transformer access power grid 2 of inverter side,
That is after the first charging stage, into the second charging stage, following steps are executed in the second charging stage:
Step 603, closed resistance by-pass switch S2 and S4, to cut off the charging resistor and inverter side of the current transformer of rectification side
Current transformer charging resistor.
Step 604, the guidance IGBT of the guidance IGBT of the current transformer of rectification side and the current transformer of inverter side are opened.
Wherein, the guidance IGBT of the current transformer of the guidance IGBT and inverter side of the current transformer of rectification side can be open-minded simultaneously,
Can also be successively open-minded, the guidance IGBT's of the current transformer of the guidance IGBT and inverter side of the current transformer of rectification side opens sequence not
Limit.
Specifically, guidance IGBT is opened there are many modes, such as it can divide and once to open or point open-minded at least twice,
Guidance IGBT can be opened one by one, and perhaps each guidance IGBT for opening different number can open all guidance IGBT or open
Logical part guidance IGBT.It can be according to the requirement to the double-end active flexible DC transmission double ended system for including clamp Shuangzi module
And the actual conditions of the double-end active flexible DC transmission double ended system including clamping Shuangzi module select optimal guidance
IGBT opens mode, and specific implementation is as previously mentioned, details are not described herein.
Step 605, the guidance IGBT for needing to open open finish and DC bus stablize after, unlock the unsteady flow of rectification side
Device.
Step 606, after DC bus-bar voltage promotion is stablized, the current transformer of inverter side is unlocked, power instruction is provided.
It should include the double-end active flexible DC transmission both-end of clamp Shuangzi module after inverter side power ascension to target value
The start-up course of system terminates, into steady state operation phase.
It should be noted that of the invention includes the starting method for clamping the flexible HVDC transmission system of Shuangzi module, no
It can be applied only to include the flexible DC transmission double ended system (including the system of two current transformers) for clamping Shuangzi module,
It can be applied to include the flexible DC transmission multi-terminal system (including the system of multiple current transformers) for clamping Shuangzi module.Also
It is to say, above-mentioned include the flexible DC transmission double ended system of clamp Shuangzi module can be single ended active double ended system, can also be with
For double-end active double ended system；The above-mentioned flexible DC transmission multi-terminal system including clamp Shuangzi module can be more for single ended active
End system, or the active multi-terminal system of multiterminal, wherein have the quantity of source be less than or equal to system end quantity.It is more
End active system regards the combination of multiple double-end active systems or single ended active system as.
Of the invention includes the starting method of the flexible HVDC transmission system of clamp Shuangzi module, is equally applicable to include pincers
The flexible HVDC transmission system of position Shuangzi module and other modules (such as half-bridge module), that is to say, that, it is not required that it is flexible
The certain all clamp Shuangzi modules of current transformer in DC transmission system, as long as including that clamp is double in flexible HVDC transmission system
Submodule, so that it may be started using starting method of the invention.
It is understood that the principle that embodiment of above is intended to be merely illustrative of the present and the exemplary implementation that uses
Mode, however the present invention is not limited thereto.For those skilled in the art, essence of the invention is not being departed from
In the case where mind and essence, various changes and modifications can be made therein, these variations and modifications are also considered as protection scope of the present invention.
Claims (8)
1. a kind of starting method of flexible HVDC transmission system, applied to the flexible HVDC transmission system for including clamp Shuangzi module
In, which is characterized in that
The flexible HVDC transmission system includes the current transformer of rectification side and the current transformer of inverter side, the current transformer of rectification side and inversion
The current transformer of side is all made of the clamp Shuangzi module,
Clamping Shuangzi module includes: 5 IGBT:T11、T12、T21、T22、T5, 2 capacitors: C1And C2And 7 diodes: D11、
D12、D21、D22、D5、D31、D32, wherein T5To guide IGBT, D5For T5Anti-paralleled diode, D31And D32For clamp diode,
T5、D5、D31And D32Clamp Shuangzi module is divided into two groups, in the first set, D11For T11Anti-paralleled diode, T11Transmitting
The first interface of pole connection clamp Shuangzi module, T11Collector connect C1And D31Cathode；D12For T12Two pole of inverse parallel
Pipe, T12Collector connection clamp Shuangzi module first interface, T12Emitter connect T5Emitter, D32Cathode, D12
Anode and capacitor C1；In the second set, D22For T22Anti-paralleled diode, T22Emitter connection clamp Shuangzi module
Second interface, T22Collector connect T5Collector, C2And D31Anode；D21For T21Anti-paralleled diode, T21Current collection
The second interface of pole connection clamp Shuangzi module, T21Emitter connect D32Anode, D21Anode and C2；
The method successively includes the first charging stage and the second charging stage；
Following steps are executed in the first charging stage:
The charging resistor access flexible HVDC transmission system including clamp Shuangzi module of the current transformer of power grid will be accessed, and
Carry out uncontrollable rectifier charging；
Following steps are executed in the second charging stage:
Open the guidance IGBT of the current transformer of access power grid；
Unlock the current transformer of rectification side；
Unlock the current transformer of inverter side；
Wherein, the guidance IGBT of the current transformer for opening access power grid is specifically included: opening the portion of the current transformer of access power grid
It separates and leads IGBT,
The minimum number for then opening the guidance IGBT of the current transformer of access power grid determines by the following method:
DC bus-bar voltage according to the dash current maximum value of other IGBT in unlock clamp Shuangzi module, before determining unlock
Value；Wherein, other IGBT refer in the clamp Shuangzi module, clamp the IGBT in Shuangzi module in addition to guiding IGBT；
According to the d-c bus voltage value before the unlock determined, the charging voltage value and often open-minded after uncontrollable rectifier charging
The value added of DC bus charging voltage, calculates the minimum number for opening guidance IGBT when one guidance IGBT.
2. the method as described in claim 1, which is characterized in that the guidance IGBT of the current transformer for opening access power grid is specific
Include:
Divide and once opens or divide the guidance IGBT for opening the current transformer of access power grid at least twice.
3. method according to claim 2, which is characterized in that if dividing the guidance for opening the current transformer of access power grid at least twice
IGBT opens the guidance IGBT of different number every time.
4. the method according to claim 1, which is characterized in that the charging electricity of the current transformer that power grid will be accessed
Before the resistance access flexible HVDC transmission system including clamp Shuangzi module, the method also includes: connection DC bus；
The progress uncontrollable rectifier charging, specifically includes:
Current transformer is accessed into power grid, and carries out uncontrollable rectifier charging by the charging resistor of the current transformer of the access power grid.
5. method as claimed in claim 4, which is characterized in that it is described open access power grid current transformer guidance IGBT it
Before, further includes: the charging resistor of the current transformer of excision access power grid.
6. method as claimed in claim 5, which is characterized in that when the flexible DC transmission system including clamp Shuangzi module
When system is single ended active flexible DC transmission double ended system,
It is described to specifically include current transformer access power grid: the current transformer of rectification side is accessed into power grid；
The charging resistor of the current transformer of the excision access power grid, specifically includes: cutting off the charging resistor of the current transformer of rectification side；
After the current transformer of the unlock inverter side, the method also includes: cut off the charging resistor of the current transformer of inverter side.
7. method as claimed in claim 6, which is characterized in that when the flexible DC transmission system including clamp Shuangzi module
When system is single ended active flexible DC transmission double ended system, after the current transformer of unlock rectification side and in the unlock inverter side
Current transformer before, the method also includes:
It is wherein electric to make that the quantity of the clamp Shuangzi module in each bridge arm of the current transformer of inverter side is gradually reduced into half
The quantity of appearance reduces half, wherein after capacitor quantity of every reduction, according to capacitor voltage equalizing strategy, controls the inverter side
Each clamp Shuangzi module rotation incision in current transformer.
8. method as claimed in claim 5, which is characterized in that when the flexible DC transmission system including clamp Shuangzi module
When system is double-end active flexible DC transmission double ended system,
It is described to specifically include current transformer access power grid: the current transformer of rectification side and the current transformer of inverter side are accessed into power grid；
The charging resistor of the current transformer of the excision access power grid, specifically includes: cutting off the charging resistor of the current transformer of rectification side
With the charging resistor of the current transformer of inverter side.
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| CN107947214B (en) * | 2016-10-12 | 2021-06-01 | 特变电工新疆新能源股份有限公司 | Starting method of multi-terminal flexible direct-current power transmission system |
| CN107947213B (en) * | 2016-10-12 | 2021-04-13 | 特变电工新疆新能源股份有限公司 | Starting method of multi-terminal flexible direct-current power transmission system with full-bridge module |
| CN106786910B (en) * | 2016-12-27 | 2019-12-27 | 中国西电电气股份有限公司 | Method simultaneously suitable for AC/DC charging of submodule of MMC converter valve |
| CN107634513B (en) * | 2017-08-21 | 2019-10-01 | 全球能源互联网研究院有限公司 | The control method and controller of MMC converter station access DC grid |
| CN108696165A (en) * | 2018-05-31 | 2018-10-23 | 西安西电电力系统有限公司 | A kind of pre-charge method of the modularization multi-level converter of clamp Shuangzi module |
| CN110739839B (en) * | 2019-09-19 | 2020-10-20 | 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 | Charging method for extra-high voltage flexible direct-current full-bridge half-bridge hybrid converter |
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