CN109950890A - A kind of full-control type energy-consuming device - Google Patents
A kind of full-control type energy-consuming device Download PDFInfo
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- CN109950890A CN109950890A CN201910225029.2A CN201910225029A CN109950890A CN 109950890 A CN109950890 A CN 109950890A CN 201910225029 A CN201910225029 A CN 201910225029A CN 109950890 A CN109950890 A CN 109950890A
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Abstract
The invention discloses a kind of full-control type energy-consuming device, which is used in the soft straight grid-connected system of wind-powered electricity generation, including controls cascade module, filter condenser and energy consumption resistor entirely；Full control cascade module puts into energy-consuming device instantaneous electric current and voltage change after being used to slow down failure, passes through the absorption power that its output voltage changes energy consumption resistor.Filter capacitor is used to inhibit the harmonic wave of fault current feed-in energy-consuming device.Resistance for dissipation is used for the transient state energy during absorption system alternating current-direct current failure, protects and is safely operated during converter station failure.Within a control period, it is 0 that full-bridge cascade module, which is absorbed with the summation that releases energy, and transient state energy is transferred completely into resistance for dissipation.The present invention includes the configuration of energy-consuming device and the voltage modulated method of structure, full control cascade module, the application that the parameter designing of energy-consuming device, the control strategy of energy-consuming device and alternating current-direct current Fault transient energy dissipate.In addition, the energy-consuming device not will increase the loss of system normal operation.
Description
Technical field
The invention belongs to electric system transmission & distribution electro-technical fields, more particularly, to a kind of full-control type energy-consuming device.
Background technique
In order to solve electric power distribution unevenness, the utilization rate of renewable energy is improved, using flexible DC transmission technology
(HVDC) carrying out the conveying of long range wind-powered electricity generation is a kind of scheme being widely recognized as.Compared with ac transmission, due to modular multilevel
Inverter (Multiple multilevel converter, MMC) can be realized active and reactive power independent control, mention
The advantages that high AC system transient stability, power oscillation damping, MMC-HVDC have become large-scale wind electricity conveying now and more inhale
The mode of gravitation.
For land wind-powered electricity generation long-distance sand transport, alternating current-direct current short trouble easily occurs for system.Current some researchs pass through
DC line event can effectively be cut off by installing dc circuit breaker (DC circuit breaker, DCCB) additional in DC line two sides
Barrier.However be limited to DCCB cut-offs speed and the overcurrent capability of MMC, existing MMC is difficult to take into account line fault ride-through capability
It is required that and station internal fault security requirement, be easy to cause converter station locking it is out of service.It is particularly directed to wind-electricity integration system, one
Denier occurs ac and dc circuit short trouble and also has the feed-in problem of a large amount of wind-powered electricity generation energy along with the rising of fault current.
Absorbing transient state energy using energy consumption resistor is a kind of safer effective measures, is had at present some about energy consumption
The research of resistance, document [Christoph Nentwig, Jens Haubrock, Robert H.Renner, and Dirk Van
Hertem. " Application of DC Choppers in HVDC Grids, " in Proc.2016IEEE
International Energy Conference (ENERGYCON), Leuven, Belgium, Apr.2016.] it proposes and adopts
The scheme of AC fault is solved with resistance for dissipation；[Cao Shuai yearns for, Yao Liangzhong, Li Yan, Lin Weixing document, Wen Jingyu wind-powered electricity generation warp
Mixed type MMC-HVDC grid-connected alternating current-direct current fault traversing strategy [J] Automation of Electric Systems, 2018,42 (07): 37-43+
49.] propose in the strategy for exchanging side outfit resistance for dissipation cooperation fault traversing, but exchanging side energy-consuming device needs three-phase uniformly to match
It sets；[it is straight through the grid-connected friendship of aerial flexible DC transmission route to yearn for wind-powered electricity generation to document by Dong Xu, Zhang Jun Stump, Wang Feng, Tao Fen, Zhou Bin
Flow fault traversing technology [J] Automation of Electric Systems, 2016,40 (18): 48-55.] have studied DC side outfit resistance for dissipation
Scheme, but do not provide the internal structure of resistance for dissipation, and put into and excision moment resistance for dissipation control device is subjected to greatly
Voltage, rush of current.It is badly in need of being equipped with energy-consuming device in Zhangbei County's engineering at present to prevent excess energy destruction converter station during failure
Normal operation ability, however there is no the energy-consuming device topology and specific control measure for being able to solve the above problem.
Summary of the invention
In view of the drawbacks of the prior art, the purpose of the present invention is to provide a kind of full-control type energy-consuming devices, it is intended to solve existing
Energy dissipation during having the resistance for dissipation in technology to can not achieve DC Line Fault causes excess energy during failure to destroy the change of current
The problem of normal operation ability stood.
The present invention provides a kind of full-control type energy-consuming devices, when for wind-powered electricity generation flexible direct current system generation alternating current-direct current failure
Energy dissipation, the energy-consuming device include: bridge-type cascade module and resistance for dissipation；The bridge-type cascade module includes N number of
The submodule being sequentially connected in series successively is denoted as the first submodule SM1, second submodule SM2... N submodule SMN, N
For the positive integer more than or equal to 2；The first submodule SM1Non- series connection end as the energy-consuming device anode output
The anode for being connected to rectification side converter station is held, one end of the resistance for dissipation is connected to the N submodule SMNNon- string
Join connecting pin, the other end of the resistance for dissipation is used to be connected to the rectification side change of current as the cathode output end of the energy-consuming device
The cathode stood.
Further, the full-control type energy-consuming device further includes filter condenser Clumped, one end is connected to described
One submodule SM1Non- series connection end, the other end is connected to the other end of the resistance for dissipation.
Further, filter condenser ClumpedCapacitance according to formulaIt obtains；Wherein, PdcFor
Nominal DC transimission power, VdcFor DC voltage, T is the control period of FB cascade module, and ε is submodule capacitor voltage fluctuation
Rate.Filter condenser ClumpedMajor function is to inhibit voltage, the electric current of feed-in full-bridge cascade module during alternating current-direct current failure humorous
Wave reduces the interference that energy-consuming device controller is subject to, meanwhile, filter condenser is also used to inhibit full-bridge cascade module dynamic modulation
The harmonic wave generated in the process.
Further, which is characterized in that the structure of N number of submodule is identical, includes: four switch control units and one
A capacitor CFB；In four switch control units two-by-two connect after again with capacitor CFBThe series connection of parallel connection, switch control unit connects
End is connect respectively as the both ends of submodule；The control terminal of four switch control units is used to receive external control signal, outside
Realize the output voltage of bridge-type cascade module in-V under the control of the control signal in portiondc~+VdcBetween change.
Wherein, the structure of four switch control units is identical, is made of IGBT and anti-paralleled diode.
Further, the number N of submoduletfAccording to formula Ntf=Vdc/VcIt obtains；The capacitor C of each submoduleFB
According to formulaIt obtains；Wherein, ε is submodule capacitor voltage stability bandwidth, and r is to dissipate
The resistance value of resistance, VcFor submodule rated capacity voltage.
Further, full-control type energy-consuming device further include: control module is used to provide the described external control signal；
The control module includes: voltage detection module, the first modulation module, adder, compensating module, the second modulation module, submodule
Block sequencing Pressure and Control module and switch triggering module；The first input end of first modulation module is connected to voltage detection module
Output end, the second input terminal, third input terminal, the 4th input terminal of the first modulation module be respectively used to receive modulation period letter
Number T, minimum output voltage signal V0With rated direct voltage Vdc；The output end of first modulation module is connected to the first of adder
Input terminal, the first modulation module are used to generate the reference voltage of full-bridge cascade module；Second input terminal of adder is connected to benefit
The output end of module is repaid, compensating module is for making up the output voltage error as caused by submodule charge and discharge in dynamic modulation；The
The input terminal of two modulation modules is connected to the output end of adder, and the second modulation module approaches modulation algorithm by nearest level,
Realize the reference voltage of the staircase waveform fitting input terminal of full-bridge cascade module；The input terminal of submodule block sequencing Pressure and Control module connects
It is connected to the output end of the second modulation module, submodule block sequencing Pressure and Control module is used to obtain meeting each submodule of staircase waveform output
The dynamic switching state of block；The input terminal of switch triggering module is connected to the output end of submodule block sequencing Pressure and Control module, opens
Trigger module is closed for obtaining IGBT trigger signal corresponding to each submodule dynamic switching.
Wherein, the first modulation module can use trapezoid modulation, the second modulation module can using NLM (NLM, recently
Level approaches modulation module).
Further, compensating module includes submodule average capacitor voltage computing unit and compensating unit, wherein submodule
The capacitance voltage that block average capacitor voltage computing unit acquires all submodules calculates average value, then carries out marking change, is input to
In compensating unit, compensating unit is controlled using PI, and the difference of actual value and reference value to average capacitance carries out proportional integration, is obtained
To dynamic voltage compensation amount, it is added on the reference voltage of full-bridge cascade module.
Further, 1.05pu upper limit threshold is arranged in voltage detection module, when DC voltage is lower than the value, voltage inspection
Surveying module output is 0, and energy-consuming device is in idle condition；Difference when DC voltage is more than 1.05pu, with upper limit threshold
Amplify by proportional integration link, the duty ratio between 0~1 is exported after limiter, is sent into the first modulation module (trapezoidal wave
Generator) in, energy-consuming device enters operating status.
Further, the modulation waveform that the first modulation module uses can be sine wave, square wave, triangular wave or trapezoidal
Wave.It is preferably trapezoid modulation in the present invention.
In embodiments of the present invention, when using trapezoid modulation, first modulation module is for generating cascade full-bridge
The output voltage reference value of module, in a cycle T, output voltage is [0, t1] in the period from VdcDrop to the V of setting0
Value, in [t1, t2] period interior holding output voltage V0, in [t2, t3] in the period from V0Rise to Vdc, in [t3, T] and the period
Interior holding Vdc；Wherein, V0For a negative voltage less than 0, so that guaranteeing that full-bridge cascade module can reach absorbs and releases energy
The summation of amount is 0.
Meanwhile to guarantee that absorbing and releasing energy is 0, modulation needs to meett2=t3-t1, Dcy=t3/ T's
Internal constraints；Wherein DcyIt is defined as duty ratio, is generated by voltage detection module.
Further, DC voltage upper limit threshold (1.05pu in the present invention), direct current are set in voltage detection module
The deviation of pressure and threshold value generates duty ratio D by PI controller and limitercy, signal is transmitted in trapezoid modulation module.Its
Middle 0≤D of duty ratiocy≤ 1, therefore limiter bound takes 1 and 0 respectively.
Further, the resistance value of the resistance for dissipation is according to formulaIt obtains, wherein VdcIt is specified
DC voltage, V0 are full-bridge cascade module output voltage minimum value, PdcFor specified dc power.
In embodiments of the present invention, when DC bipolar short trouble occurs for system, after dc circuit breaker is cut-off, submodule
Block discharge loop is cut off, and wind-powered electricity generation feed-in power rises DC voltage；When DC voltage is more than threshold value 1.05pu, energy consumption
Device duty ratio is greater than 0, and energy-consuming device investment absorbs wind-powered electricity generation energy, protects safety of the converter station during failure；Fault clearance
Afterwards, breaker closes a floodgate again after 200ms goes to dissociate, and DC voltage is again stable in rated value, and energy-consuming device duty ratio is
0, it is automatically stopped operation, the fast quick-recovery of system to normal condition；
When AC three-phase ground short circuit failure occurs for system inverter side converter station, dc power can not be sent out, alternating current-direct current
Imbalance power forces DC voltage to increase, and energy-consuming device starts automatically after DC voltage is more than threshold value 1.05pu, absorbs not
Balance power makes system continue to run, and dc power continues to send out after failure is removed, and DC voltage drops to specified
Value, energy-consuming device automatically exit from operation.Wherein, dc circuit breaker is not necessarily to movement during AC fault.
In embodiments of the present invention, full-bridge cascade module need to introduce submodule average capacitor voltage control module, output
Reference voltage on module capacitance deviation compensation to the output reference voltage of full-bridge cascade module, after obtaining compensating approach.Later,
Modulation is approached using conventional minimum level and algorithm is pressed in sequence, obtains the trigger signal of each submodule switching device.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, can obtain down and show
Beneficial effect:
(1) the invention proposes a kind of novel full control energy-consuming device topologys and control strategy；The topology can be realized friendship
During DC Line Fault energy it is smooth transfer and dissipate, ensure that system safe operation and fast quick-recovery.Reduce energy consumption dress
The rush of current that is born of investment moment is set, reduces the technical difficulty of energy-consuming device and to ambient enviroment bring electromagnetic interference.
(2) present invention directly controls the full-bridge modules output voltage of energy-consuming device by detecting DC voltage, has independent
Detect and control logic, convenient for being used cooperatively with devices such as dc circuit breaker, fault current limiters.
(3) present invention has carried out detailed analysis to the structure, parameter designing and control strategy of energy-consuming device, has filled up soft
The blank of property DC grid energy-consuming device design field, can be obtained energy-consuming device in high-voltage large-capacity engineering according to calculation formula
Configuration parameter, meet the application demand of flexible direct current power grid.
Detailed description of the invention
Fig. 1 is a kind of topological structure schematic diagram of full-control type energy-consuming device provided in an embodiment of the present invention；
Fig. 2 is that full-control type energy-consuming device provided in an embodiment of the present invention applies the knot in the soft straight grid-connected system of both-end wind-powered electricity generation
Structure schematic diagram；
Fig. 3 is the voltage, power and absorption energy waveform schematic diagram of full-bridge cascade module provided in an embodiment of the present invention；
Fig. 4 is the inner modulation the constraint relationship schematic diagram of full-bridge cascade module provided in an embodiment of the present invention；
Fig. 5 is trapezoid modulation method implementation flow chart provided in an embodiment of the present invention；
Fig. 6 is the voltage, power and absorption energy waveform schematic diagram of resistance for dissipation provided in an embodiment of the present invention；
Fig. 7 is the whole control block diagram of full-control type energy-consuming device provided in an embodiment of the present invention.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Full-control type energy-consuming device provided by the invention be mainly used for wind-powered electricity generation flexible direct current system occur alternating current-direct current failure when
Energy dissipation ensures the transient security of inverter, realizes the fast quick-recovery of system.
In the present invention, by structure, inner modulation method, parameter designing and the control method to full-control type energy-consuming device into
Row design and the application verification in wind-electricity integration system, the energy for realizing alternating current-direct current failure in wind-electricity integration system accurately consume
It dissipates, and lesser di/dt reduces system and the performance requirement of power electronic devices in energy-consuming device and the electromagnetism of generation are done
It disturbs.The corresponding modification of size that only need to will cascade full-bridge modules, energy consumption resistor when applied to high voltage large capcity occasion, has efficient
Rate, control response rapidly and accurately, the simple advantage of overall system structure.
The present invention provides a kind of full-control type energy-consuming devices, when for wind-powered electricity generation flexible direct current system generation alternating current-direct current failure
Energy dissipation, the energy-consuming device include bridge-type cascade module and resistance for dissipation, in which: energy-consuming device is by bridge-type cascade module
In series with resistance for dissipation, positive and negative electrode is connected with the DC side positive and negative electrode of rectification side converter station respectively, wherein full-bridge
The anode of the outlet connection rectification side converter station of cascade module, the cathode of the outlet connection rectification side converter station of resistance for dissipation.
Above-mentioned a kind of full-control type energy-consuming device in the present invention, wherein further include being connected in parallel on full-bridge cascade module and dissipation
Filter condenser by resistance branch, major function be inhibit alternating current-direct current failure during feed-in full-bridge cascade module voltage,
Current harmonics reduces the interference that energy-consuming device controller is subject to, meanwhile, filter condenser is also used to inhibit full-bridge cascade module dynamic
The harmonic wave generated in state modulated process.
In the embodiment of the present invention, full-bridge cascade module includes several bridge-type submodules, each bridge-type submodule packet
Include four switch control units and a capacitor.Wherein switch control unit is made of IGBT and anti-paralleled diode.
In the embodiment of the present invention, the output voltage of bridge-type cascade module can be in-Vdc~+VdcBetween change, modulate
Waveform can be sine wave, square wave, triangular wave or trapezoidal wave etc., use trapezoid modulation in the present invention.
In the embodiment of the present invention, trapezoid modulation is used to generate the output voltage reference value of cascade full-bridge modules, at one
In cycle T, output voltage is [0, t1] in the period from VdcDrop to the V of setting0Value, in [t1, t2] period interior holding output
Voltage V0, in [t2, t3] in the period from V0Rise to Vdc, in [t3, T] and V is kept in the perioddc.Wherein, V0For one less than 0
Negative voltage, thus guarantee full-bridge cascade module can reach absorb and release energy summation be 0.
In the embodiment of the present invention, to guarantee that absorbing and releasing energy is 0, modulation needs to meett2=t3-t1,
Dcy=t3The internal constraints of/T.Wherein DcyIt is defined as duty ratio, is generated by voltage detection module.
In the embodiment of the present invention, DC voltage upper limit threshold (1.05pu in the present invention), direct current is arranged in voltage detection module
The deviation of voltage and threshold value generates duty ratio D by PI controller and limitercy, signal is transmitted in trapezoid modulation module.
Wherein 0≤D of duty ratiocy≤ 1, therefore limiter bound takes 1 and 0 respectively.
In the embodiment of the present invention, the calculating of the capacitor of required submodule number and each submodule is public in full-bridge cascade module
Formula is respectively as follows: Ntf=Vdc/Vc,Wherein, ε is submodule capacitor voltage stability bandwidth,
R is the resistance value of resistance for dissipation, VcFor submodule rated capacity voltage, V0For full-bridge cascade module output voltage minimum value.
In the embodiment of the present invention, full-bridge cascade module need to introduce submodule average capacitor voltage control module, export submodule
In the compensation to the output reference voltage of full-bridge cascade module of block capacitance deviation, the reference voltage after obtaining compensating approach.Later, it adopts
Modulation is approached with conventional minimum level and algorithm is pressed in sequence, obtains the trigger signal of each submodule switching device.
In the embodiment of the present invention, control type energy-consuming device further include: control module is used to provide the described external control letter
Number；Control module includes: voltage detection module, the first modulation module, adder, compensating module, the second modulation module, submodule
The Pressure and Control module that sorts and switch triggering module；The first input end of first modulation module is connected to voltage detection module
Output end, the second input terminal, third input terminal, the 4th input terminal of the first modulation module are respectively used to receive modulated periodic signal
T, minimum output voltage signal V0With rated direct voltage Vdc；It is first defeated to be connected to adder for the output end of first modulation module
Enter end, the first modulation module is used to generate the reference voltage of full-bridge cascade module；Second input terminal of adder is connected to compensation
The output end of module, compensating module is for making up the output voltage error as caused by submodule charge and discharge in dynamic modulation；Second
The input terminal of modulation module is connected to the output end of adder, and the second modulation module approaches modulation algorithm by nearest level, real
The reference voltage of the staircase waveform fitting input terminal of existing full-bridge cascade module；The input terminal of submodule block sequencing Pressure and Control module connects
To the output end of the second modulation module, submodule block sequencing Pressure and Control module is used to obtain meeting each submodule of staircase waveform output
Dynamic switching state；The input terminal of switch triggering module is connected to the output end of submodule block sequencing Pressure and Control module, switch
Trigger module is for obtaining IGBT trigger signal corresponding to each submodule dynamic switching.
In the embodiment of the present invention, resistance for dissipation computing the resistor value formula are as follows:Wherein VdcFor nominal DC
Voltage, V0For full-bridge cascade module output voltage minimum value, PdcFor specified dc power.
In the embodiment of the present invention, the capacitance calculation formula of filter condenser are as follows:Wherein PdcIt is specified
Direct current transmission power, VdcFor DC voltage, T is the control period of FB cascade module, and ε is submodule capacitor voltage stability bandwidth.Filter
Wave capacitor ClumpedMajor function is voltage, the current harmonics for inhibiting feed-in full-bridge cascade module during alternating current-direct current failure, is reduced
The interference that energy-consuming device controller is subject to, meanwhile, filter condenser is also used to inhibit during full-bridge cascade module dynamic modulation
The harmonic wave of generation.
In the embodiment of the present invention, when DC bipolar short trouble occurs for system, after dc circuit breaker is cut-off, submodule
Discharge loop is cut off, and wind-powered electricity generation feed-in power rises DC voltage.When DC voltage is more than threshold value 1.05pu, energy consumption dress
Duty ratio is set greater than 0, energy-consuming device investment absorbs wind-powered electricity generation energy, protects safety of the converter station during failure.After fault clearance,
Breaker closes a floodgate again after 200ms goes to dissociate, and DC voltage is again stable in rated value, and energy-consuming device duty ratio is 0, from
Move out of service, the fast quick-recovery of system to normal condition.
When AC three-phase ground short circuit failure occurs for system inverter side converter station, dc power can not be sent out, alternating current-direct current
Imbalance power forces DC voltage to increase, and energy-consuming device starts automatically after DC voltage is more than threshold value 1.05pu, absorbs not
Balance power makes system continue to run, and dc power continues to send out after failure is removed, and DC voltage drops to specified
Value, energy-consuming device automatically exit from operation.Wherein, dc circuit breaker is not necessarily to movement during AC fault.
The present invention provides a kind of full-control type energy-consuming device, by being configured to it and structure, inner modulation method, parameter are set
Meter, control strategy is designed and the application verification in wind-electricity integration system, realizes alternating current-direct current event in wind-electricity integration system
The energy of barrier accurately dissipates, and lesser di/dt reduces system for the performance requirement of power electronic devices in energy-consuming device
With the electromagnetic interference of generation.The size pair of full-bridge modules, energy consumption resistor need to will be only cascaded when applied to high voltage large capcity occasion
Should modify, have the advantages that high efficiency, control response rapidly and accurately, overall system structure it is simple, solve conventional resistance for dissipation
In high-voltage large-capacity applications, rush of current is excessively high, dissipated power can not the technological deficiencies such as active control.
Scheme using full-bridge cascade module and resistance for dissipation energy-consuming device in series of the invention, it is possible to reduce dissipate
The instantaneous power absorbed needed for resistance, while guaranteeing that full-bridge modules will not absorb transient state energy, therefore will not be to full-bridge grade gang mould
Block causes overvoltage injury.
Fig. 1 is a kind of full-control type energy-consuming device provided by the present invention, and alternating current-direct current occurs for wind-powered electricity generation flexible direct current system
Energy dissipation when failure, the energy-consuming device include bridge-type cascade module and resistance for dissipation, in which:
Energy-consuming device is in series by bridge-type cascade module and resistance for dissipation, positive and negative electrode respectively with the rectification side change of current
The DC side positive and negative electrode stood is connected, wherein the anode of the outlet connection rectification side converter station of full-bridge cascade module, resistance for dissipation
Outlet connection rectification side converter station cathode.
One of present invention full-control type energy-consuming device, wherein further include being connected in parallel on full-bridge cascade module and resistance for dissipation
The filter condenser in branch roadside, major function are voltage, the electric current for inhibiting feed-in full-bridge cascade module during alternating current-direct current failure
Harmonic wave reduces the interference that energy-consuming device controller is subject to, meanwhile, filter condenser is also used to that full-bridge cascade module dynamic is inhibited to adjust
The harmonic wave generated during system.
In full-control type energy-consuming device provided in an embodiment of the present invention, full-bridge cascade module includes several bridge-type submodules
Block, each bridge-type submodule include four switch control units and a capacitor.Wherein switch control unit by IGBT and
Anti-paralleled diode is constituted.
Fig. 2 is a kind of concrete application occasion of example provided by the present invention, and in wind-electricity integration system, wind-powered electricity generation is by rising
It is transferred to after pressure in the MMC of wind field side, grid side MMC is sent to by overhead line through over commutation, be sent into AC network after inversion.?
The two sides positive and negative electrode transmission line of electricity of overhead line installs dc circuit breaker respectively, to cut off direct-current short circuit fault current rapidly.Full control
Type energy-consuming device is connected in parallel on the DC side of wind field side MMC, absorbs the transient state energy during failure, protects the safety of two sides MMC.
Fig. 3 is output voltage, power and the energy of bridge-type cascade module in full-control type energy-consuming device, and voltage can be with
In-Vdc~+VdcBetween change, modulation waveform can be for sine wave, square wave, triangular wave or trapezoidal wave etc., using ladder in the present invention
The modulation of shape wave.
In full-control type energy-consuming device provided in an embodiment of the present invention, trapezoid modulation is used to generate cascade full-bridge modules
Output voltage reference value, in a cycle T, output voltage is [0, t1] in the period from VdcDrop to the V of setting0Value,
[t1, t2] period interior holding output voltage V0, in [t2, t3] in the period from V0Rise to Vdc, in [t3, T] and it is protected in the period
Hold Vdc.Wherein, V0For a negative voltage less than 0, so that guaranteeing that full-bridge cascade module can reach absorbs and releases energy
Summation is 0.
Fig. 4 is the modulation internal constraint of full-bridge cascade module in full-control type energy-consuming device, to guarantee to absorb and release energy
For O, modulation needs to meetIn the flexible direct current system of voltage rating ± 320kV, t1、V0And VdcRelationship such as
Shown in Fig. 4.
Fig. 5 is the voltage modulated process of full-bridge cascade module, defines duty ratio Dcy, cycle T, DC voltage (initial voltage)
Vdc, bottom voltage V0Input modulator, calculation stages inflection point t1、t2、t3The constraint relationship.Work as DcyWhen > 0, modulator enters work
Make state, the stage according to locating for different moments calculates the output voltage of full-bridge cascade module, finally obtains modulation voltage as week
The trapezoidal wave of phase property, as shown in Figure 3.
In full-control type energy-consuming device provided in an embodiment of the present invention, duty ratio DcyIt is generated, is set by voltage detection module
DC voltage upper limit threshold (1.05pu in the present invention) is set, the deviation of DC voltage and threshold value is produced by PI controller and limiter
Raw duty ratio Dcy, signal is transmitted in trapezoid modulation module.Wherein 0≤D of duty ratiocy≤ 1, therefore limiter bound point
1 and 0 are not taken.t2=t3-t1, Dcy=t3/T。
According to t in Fig. 3m1And tm2Corresponding ENERGY EmaxAnd Emin, required submodule number in available full-bridge cascade module
It is respectively as follows: N with the calculation formula of the capacitor of each submoduletf=Vdc/Vc,Its
Middle ε is submodule capacitor voltage stability bandwidth, and r is the resistance value of resistance for dissipation, VcFor submodule rated capacity voltage.
Wherein, the full-bridge cascade module need to introduce submodule average capacitor voltage control module, output sub-module capacitor
Reference voltage on deviation compensation to the output reference voltage of full-bridge cascade module, after obtaining compensating approach.Later, using routine
Minimum level approach modulation and sequence press algorithm, obtain the trigger signal of each submodule switching device.
Fig. 6 is voltage, power and the energy in the resistance for dissipation, [0, t3] stage absorb energy are as follows:It is hereby achieved that resistance for dissipation computing the resistor value formula are as follows:
Wherein PdcFor specified dc power.The capacitance calculation formula of filter condenser are as follows:
Fig. 7 is the whole control block diagram of full-control type energy-consuming device comprising voltage detection module, staircase modulation module, son
Module capacitance voltage compensation module, nearest level approach modulation module (NLM), the Pressure and Control of submodule block sequencing and switch triggering mould
Block.When DC bipolar short trouble occurs for system, after dc circuit breaker is cut-off, submodule discharge loop is cut off, and wind
Electric feed-in power rises DC voltage.When DC voltage is more than threshold value 1.05pu, energy-consuming device duty ratio DcyGreater than 0, consumption
Energy device investment absorbs wind-powered electricity generation energy, protects safety of the converter station during failure.After fault clearance, breaker passes through 200ms
It goes after dissociating to close a floodgate again, DC voltage is again stable in rated value, and energy-consuming device duty ratio is 0, is automatically stopped operation, system
Fast quick-recovery is to normal condition.When AC three-phase ground short circuit failure occurs for system inverter side converter station, dc power can not
It sends out, alternating current-direct current imbalance power forces DC voltage to increase, and energy-consuming device is automatic after DC voltage is more than threshold value 1.05pu
Starting, absorbing imbalance power makes system continue to run, and dc power continues to send out after failure is removed, DC voltage
Rated value is dropped to, energy-consuming device automatically exits from operation.Wherein, dc circuit breaker is not necessarily to movement during AC fault.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (10)
1. energy dissipation when alternating current-direct current failure occurs for wind-powered electricity generation flexible direct current system for a kind of full-control type energy-consuming device, special
Sign is that the energy-consuming device includes: bridge-type cascade module and resistance for dissipation；
The bridge-type cascade module includes N number of submodule being sequentially connected in series, and is successively denoted as the first submodule SM1, the second son
Module SM2... N submodule SMN, N is the positive integer more than or equal to 2；
The first submodule SM1Non- series connection end as the energy-consuming device cathode output end for being connected to rectification
The anode of side converter station, one end of the resistance for dissipation are connected to the N submodule SMNNon- series connection end, the consumption
The other end for dissipating resistance is used to be connected to the cathode of rectification side converter station as the cathode output end of the energy-consuming device.
2. full-control type energy-consuming device as described in claim 1, which is characterized in that the full-control type energy-consuming device further include: filter
Wave capacitor Clumped, one end is connected to the first submodule SM1Non- series connection end, the other end is connected to the consumption
Dissipate the other end of resistance.
3. full-control type energy-consuming device as described in claim 1, which is characterized in that the structure of N number of submodule is identical, includes:
Four switch control units and a capacitor CFB；
In four switch control units two-by-two connect after again with capacitor CFBParallel connection, the series connection end difference of switch control unit
Both ends as submodule；
The control terminal of four switch control units is used to receive external control signal, real under the control of external control signal
The output voltage of existing bridge-type cascade module is in-Vdc~+VdcBetween change.
4. full-control type energy-consuming device as described in any one of claims 1-3, which is characterized in that the full-control type energy-consuming device is also
It include: the control module for being used to provide the described external control signal；
The control module include: voltage detection module, the first modulation module, adder, compensating module, the second modulation module,
Submodule block sequencing Pressure and Control module and switch triggering module；
The first input end of first modulation module is connected to the output end of voltage detection module, and the second of the first modulation module
Input terminal, third input terminal, the 4th input terminal are respectively used to receive modulated periodic signal T, minimum output voltage signal V0And volume
Determine DC voltage Vdc；The output end of first modulation module is connected to the first input end of adder, and the first modulation module is for producing
The reference voltage of raw full-bridge cascade module；The voltage detection module is used to generate the duty ratio of staircase generator, control consumption
Can device be in idle condition when system operates normally, when system jam, is in operating status；
Second input terminal of the adder is connected to the output end of compensating module, and the compensating module is used for according to comparing submodule
The actual value of block capacitance voltage average value and the deviation acquisition of rated value make up in dynamic modulation as caused by submodule charge and discharge
Output voltage error；
The input terminal of second modulation module is connected to the output end of adder, and second modulation module is used for according to difference
Moment corresponding output voltage piecewise function calculates the reference voltage for obtaining the staircase waveform fitting input terminal of full-bridge cascade module；
The input terminal of the submodule block sequencing Pressure and Control module is connected to the output end of the second modulation module, the submodule row
Sequence Pressure and Control module is used to obtain each son for meeting trapezoidal wave output according to bubble sort method and submodule electric voltage equalization principle
The dynamic switching state of module；
The input terminal of the switch triggering module is connected to the output end of submodule block sequencing Pressure and Control module, the switch triggering
Module is used to obtain the triggering letter of IGBT corresponding to each submodule according to each submodule switching state that sequence Pressure and Control obtain
Number.
5. full-control type energy-consuming device as claimed in claim 4, which is characterized in that the compensating module includes: that submodule is average
Capacitance voltage computing unit and compensating unit；
The submodule average capacitor voltage computing unit is used to acquire the capacitance voltage of all submodules and calculates its average value
Laggard rower is changed；
The input terminal of the compensating unit is connect with the output end of the submodule average capacitor voltage computing unit, for flat
The actual value of equal capacitor and the difference of reference value carry out proportional integration, obtain dynamic voltage compensation amount.
6. full-control type energy-consuming device as described in claim 4 or 5, which is characterized in that the direct current in the voltage detection module
Upper voltage limit threshold value is 1.05pu；When DC voltage is more than 1.05pu, the difference of DC voltage and upper limit threshold passes through ratio
Integral amplification, the duty ratio exported after clipping are exported to the first modulation module, and the energy-consuming device enters operating status.
7. full-control type energy-consuming device as claimed in any one of claims 1 to 6, it is characterised in that: the filter condenser Clumped
Capacitance according to formulaIt obtains；The resistance value of the resistance for dissipation is according to formulaIt obtains
?；The number N of the submodule is according to formula N=Vdc/VcIt obtains；The capacitor C of each submoduleFBCapacitance according to the following formula
It obtains:The modulation of full-bridge cascade module needs to meett2=t3-
t1, Dcy=t3The internal constraints of/T；
Wherein, PdcFor nominal DC transimission power, VdcFor DC voltage, T is the control period of bridge-type cascade module, and ε is son
Module capacitance voltage fluctuation rate, DcyIt is defined as duty ratio, V0For full-bridge cascade module output voltage minimum value, r is resistance for dissipation
Resistance value, VcFor submodule rated capacity voltage.
8. such as the described in any item full-control type energy-consuming devices of claim 4-7, which is characterized in that first modulation module uses
Modulation waveform be sine wave, square wave, triangular wave or trapezoidal wave.
9. full-control type energy-consuming device as claimed in claim 8, which is characterized in that when using trapezoid modulation, described first
Modulation module is used to generate the output voltage reference value of cascade full-bridge modules, and in a cycle T, output voltage is [0, t1] when
Between in section from VdcDrop to the V of setting0Value, in [t1, t2] period interior holding output voltage V0, in [t2, t3] in the period from
V0Rise to Vdc, in [t3, T] and V is kept in the perioddc；Wherein, V0For a negative voltage less than 0.
10. such as the described in any item full-control type energy-consuming devices of claim 1-9, which is characterized in that when DC bipolar occurs for system
When short trouble, after dc circuit breaker is cut-off, submodule discharge loop is cut off, and wind-powered electricity generation feed-in power makes on DC voltage
It rises；When DC voltage is more than threshold value 1.05pu, energy-consuming device duty ratio is greater than 0, and energy-consuming device investment absorbs wind-powered electricity generation energy, protects
Protect safety of the converter station during failure；
When AC three-phase ground short circuit failure occurs for system inverter side converter station, dc power can not be sent out, and alternating current-direct current is uneven
Weighing apparatus power forces DC voltage to increase, and energy-consuming device starts automatically after DC voltage is more than threshold value 1.05pu, absorbs uneven
Power makes system continue to run.
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| CN112327082A (en) * | 2020-10-30 | 2021-02-05 | 国网江苏省电力有限公司电力科学研究院 | Flexible direct current engineering complete energy consumption device testing method, device and system |
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| CN113964856B (en) * | 2021-10-11 | 2024-03-26 | 南方电网科学研究院有限责任公司 | Control method of half-bridge sub-module type direct current energy consumption device |
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