CN108509674A - A kind of improvement mixing MMC operation reliability evaluations model and method based on Multiple Time Scales thermal damage - Google Patents
A kind of improvement mixing MMC operation reliability evaluations model and method based on Multiple Time Scales thermal damage Download PDFInfo
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Abstract
The invention discloses a kind of improvement mixing MMC operation reliability evaluations model and method based on Multiple Time Scales thermal damage, mainly includes the following steps that：1) real time data of wind-powered electricity generation Transmission system is obtained.The real time data includes mainly wind speed, temperature and electrical parameters of equipment.2) mixing MMC power device Reliability Evaluation Models are established using mixing MMC operation characteristics and Miner ' s defect theories according to the initial data.The power device of the wind-powered electricity generation Transmission system includes mainly insulated gate bipolar crystal IGBT and crystal diode Diode.3) the capacitor Reliability Evaluation Model that meter and failure SM voltages are shared is established in the influence according to failure SM to intact SM capacitances.4) analysis mixing MMC device loss distribution mixes MMC operation reliability evaluation models to establish meter and the multi-mode improvement of SM.It the composite can be widely applied in the operation reliability evaluation that the regenerative resources such as wind-powered electricity generation transmit grid-connected middle mixing MMC.
Description
Technical field
The present invention relates to wind-powered electricity generation transportation art, specifically a kind of improvement mixing MMC fortune based on Multiple Time Scales thermal damage
Row Reliability Evaluation Model and method.
Background technology
Modular multilevel converter type D.C. high voltage transmission (MMC-HVDC) is to realize large-scale wind power station and power grid
Connect the power transmission mode of great foreground.Wherein, modularization multi-level converter (MMC) has modularized design, output electricity
The features such as pressing quality high, is the key equipment in VSC-HVDC, and operational reliability is related to the safety and stability fortune of VSC-HVDC
Row.However, the random fluctuation of wind speed makes MMC transimission powers change greatly, power and temperature fluctuation further result in power in MMC
Device junction temperature amplitude and fluctuating change are apparent, significantly impact the reliability of MMC.Meanwhile increasingly with wind-powered electricity generation transimission power
Greatly, MMC voltage class rises therewith, and MMC devices is caused gradually to increase, and device, which increases, makes the electric parameters such as power frequency, switching frequency
MMC operational reliabilitys are influenced to increase.However, the conventional equipment reliability assessment based on statistical data has ignored current operation item
Influence of the part to equipment dependability causes its reliability assessment result and actual motion deviation larger.Therefore, it is necessary to consider ring
MMC operation reliability evaluation models in wind-powered electricity generation transport system are studied in the influence of border factor, electric parameter.
In recent years, many researchs have been done in terms of MMC reliability considerations both at home and abroad, but have been based on device constant failure-rate more
Model evaluation MMC reliabilities, or MMC device fault rates are modified by introducing voltage modifying factor.But due to power device
The failure rate of part changes over time, and is unsatisfactory for the primary condition of constant failure-rate model, therefore, it is necessary to be based on power device
The failure mechanism of part further studies MMC operation reliability evaluation models.In engineer application, mixing MMC is due to good straight
Fault ride-through capacity and lower cost are flowed, current practicable application scheme is become.
Invention content
Present invention aim to address problems of the prior art.
To realize the present invention purpose and the technical solution adopted is that a kind of such, changing based on Multiple Time Scales thermal damage
Into mixing MMC operation reliability evaluation models, mainly include the following steps that：
1) real time data of wind-powered electricity generation Transmission system is obtained.The real time data includes mainly that wind speed, temperature and equipment are electrical
Parameter.
2) mixing MMC work(is established using mixing MMC operation characteristics and Miner ' s defect theories according to the initial data
Rate device reliability assessment models.The power device of the wind-powered electricity generation Transmission system mainly include insulated gate bipolar crystal IGBT and
Crystal diode Diode.
Further, the key step for establishing the mixing MMC power device Reliability Evaluation Models is as follows：
2.1) mixing MMC power device Multiple Time Scales junction temperatures are calculated.Key step is as follows：
2.1.1 wind-powered electricity generation Transmission system wind turbine output power P) is determinedWToutWith sampling instant tnCorresponding wind speedRelationship.
I-th of wind turbine output power P of wind-powered electricity generation Transmission systemWTout,iWith sampling instant tnCorresponding wind speedThe following institute of relationship
Show：
In formula, PratedFor wind turbine rated power.Vcutin、VratedAnd VcutoutIt respectively cuts wind speed, rated wind speed and cuts
Go out wind speed.kpIt indicates and atmospheric density and the relevant coefficient of wind turbine area.NWTFor wind turbine sum in wind-powered electricity generation Transmission system.N be to
Total number of sample points until the current time of running.tnFor sampling instant.For wind speed.I is arbitrary wind turbine.I=1 ..., NWT。
Mix the transmission power P of MMCMMCoutAs follows：
In formula, NWTFor wind turbine sum in wind-powered electricity generation Transmission system.I is arbitrary wind turbine.I=1 ..., NWT。PWTout,iIt is i-th
Wind turbine output power.
2.1.2) according to formula 1, mixing MMC bridge arm currents are calculated.
Bridge arm current I in A phasesauWith A phase lower bridge arm electric currents IadIt is as follows respectively：
In formula, IdcFor DC side electric current.ImFor ac-side current peak value.For power-factor angle.f0For fundamental frequency.
DC side electric current IdcAs follows：
In formula, UdcFor DC voltage.PMMCoutTo mix the transmission power of MMC.
Ac-side current peak ImAs follows：
In formula, PMMCoutTo mix the transmission power of MMC.For power-factor angle.UacFor exchange side voltage effective value.
2.1.3 j-th of switch periods average loss of bridge arm IGBT in A phases) is calculated.
J-th of switch periods average loss of bridge arm IGBT in A phasesAs follows：
In formula, Rce、UceoAnd τTRespectively IGBT forward conductions resistance, threshold voltage and duty ratio.aT、bTAnd cTFor IGBT
Dynamic characteristic fitting parameter.UratedFor IGBT rated voltages.fswAnd ρTThe respectively switching frequency of IGBT and temperature coefficient.
J is arbitrary switch periods.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.IauFor bridge arm current in A phases.
UdcFor DC voltage.
Switch periods number nswAs follows：
nsw=fsw/f0。 (7)
In formula, fswFor the switching frequency of IGBT.f0For fundamental frequency.
2.1.4 j-th of switch periods average loss of Diode) is calculated
J-th of switch periods average loss of DiodeAs follows：
In formula：Rd、UdAnd τDRespectively Diode forward conductions resistance, threshold voltage and duty ratio.aD、bDAnd cDFor Diode
Dynamic characteristic fitting parameter.UDFor Diode rated voltages.fdwAnd ρDThe respectively switching frequency of Diode and temperature coefficient.
IauFor bridge arm current in A phases.UdcFor DC voltage.
2.1.5 the junction temperature of j-th of switch periods of IGBT in mixing MMC) is calculated
The junction temperatureAs follows：
In formula,For sampling instant tnCorresponding temperature.For j-th of switch periods IGBT knot-shell heat of r ranks
The temperature difference of RC parallel units in network.R indicates arbitrary order.R=1,2,3,4.For j-th of switch periods IGBT shells-heat dissipation
The temperature difference of RC parallel units in piece ther mal network.For RC in j-th of switch periods IGBT cooling fins-environment ther mal network and receipts or other documents in duplicate
The temperature difference of member.J is arbitrary switch periods.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.
The temperature difference of RC parallel units in j-th of switch periods IGBT knots-shell network of r ranksAs follows：
In formula, RTjc,rFor thermal resistance.τTjc,rFor thermal resistance RTjc,rThermal time constant.TswFor switch periods.It is r ranks
- 1 switch periods IGBT knots-shell ther mal network of jth in RC parallel units the temperature difference.E is the truth of a matter of natural logrithm function, about
2.71828。。For j-th of switch periods average loss of bridge arm IGBT in A phases.J is arbitrary switch periods.J=1 ..., nsw。
nswFor switch periods sum in a fundamental frequency cycles.
The temperature difference of RC parallel units in j-th of switch periods IGBT shells-cooling fin networkAs follows：
In formula, RTchFor thermal resistance.τTchFor thermal resistance RTchThermal time constant.TswFor switch periods.It is that jth -1 is opened
Close the temperature difference of RC parallel units in period IGBT shell-cooling fin ther mal network.E is the truth of a matter of natural logrithm function, about
2.71828。。For j-th of switch periods average loss of bridge arm IGBT in A phases.J is arbitrary switch periods.J=1 ..., nsw。
nswFor switch periods sum in a fundamental frequency cycles.
J-th of switch periods IGBT is the temperature difference of RC parallel units in cooling fin-environment networkAs follows：
In formula, RhaFor thermal resistance.τhaFor thermal resistance RhaThermal time constant.TswFor switch periods.It is that jth -1 is opened
Close the period temperature difference of RC parallel units in IGBT ther mal networks.J is arbitrary switch periods.J=1 ..., nsw。nswFor a fundamental frequency week
Switch periods sum in phase.For j-th of switch periods average loss of bridge arm IGBT in A phases.For bridge arm in A phases
J-th of switch periods average loss of Diode.
2.1.6 the junction temperature of j-th of switch periods of Diode in mixing MMC) is calculated
The junction temperatureAs follows：
In formula,For sampling instant tnCorresponding temperature.For j-th of switch periods Diode knot-shell heat of r ranks
The temperature difference of RC parallel units in network.R indicates arbitrary order.R=1,2,3,4.For j-th of switch periods Diode shells-heat dissipation
The temperature difference of RC parallel units in piece ther mal network.For RC in j-th of switch periods IGBT cooling fins-environment ther mal network and receipts or other documents in duplicate
The temperature difference of member.
J is arbitrary switch periods.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.
The temperature difference of RC parallel units in j-th of switch periods Diode knots-shell networkAs follows：
In formula, RDjc,rFor thermal resistance.τDjc,rFor thermal resistance RDjc,rThermal time constant.TdwFor switch periods.It is jth -1
The temperature difference of RC parallel units in a switch periods Diode knots-shell ther mal network.J is arbitrary switch periods.J=1 ..., nsw。nswFor
Switch periods sum in one fundamental frequency cycles.For j-th of switch periods average loss of bridge arm Diode in A phases.
The temperature difference of RC parallel units in j-th of switch periods Diode shells-cooling fin networkAs follows：
In formula, RDchFor thermal resistance.τDchFor thermal resistance RDchThermal time constant.TswFor switch periods.It is that jth -1 is opened
Close the temperature difference of RC parallel units in period Diode shell-cooling fin ther mal network.Week is switched for bridge arm Diode in A phases j-th
Phase average loss.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.
2.2) MMC power device Multiple Time Scales reliability assessments are mixed.Key step is as follows：
2.2.1 IGBT low-frequency cycles corresponding cycle invalidation period number N) is calculatedTf_L.Recycle invalidation period number NTf_LIt is as follows
It is shown：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TTjmax_LFor IGBT
Low frequency junction temperature maximums.TTjmin_LFor IGBT low frequency junction temperature minimum values.ILFor IGBT low frequency aluminium bonding line current effective values.E is certainly
The truth of a matter of right logarithmic function, about 2.71828..
The corresponding cycle invalidation period number N of IGBT fundamental frequency cyclesTf_FAs follows：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TTjmax_FFor IGBT
Fundamental frequency junction temperature maximums.TTjmin_FFor IGBT fundamental frequency junction temperature minimum values.IFFor IGBT fundamental frequency aluminium bonding line current effective values.E is certainly
The truth of a matter of right logarithmic function, about 2.71828..
According to Miner ' s defect theories and formula (17), IGBT is in 0-tnThe life consumption CL at momentT(tn) as follows：
In formula, NTsum_LFor 0-tnMoment low frequency thermal cycle sum.NT_L,gAnd NTf_L,gRespectively IGBT g infra-low frequency heat is followed
The corresponding times of thermal cycle of ring and cycle invalidation period number.NT_F,qAnd NTf_F,qRespectively T pairs of sampling time intervals of q-th of IGBT
The fundamental frequency times of thermal cycle and cycle invalidation period number answered.N is the total number of sample points until the current time of running.NTsum_LFor
Low frequency thermal cycle sum.
IGBT sampling instants tnThe mean time to failure, MTTF MTTF of corresponding time interval TT(tn) as follows：
In formula, CLT(tn) be IGBT in 0-tnThe life consumption at moment.T is sampling time interval.
IGBT failure rates λT(tn) as follows：
In formula, MTTFT(tn) it is IGBT sampling instants tnThe mean time to failure, MTTF of corresponding time interval T.
IGBT reliabilitys RT(tn)As follows：
In formula, λT(tn) it is IGBT failure rates.tnFor sampling instant.
2.2.2 Diode low-frequency cycles corresponding cycle invalidation period number N) is calculatedDf_L.Recycle invalidation period number NDf_LIt is as follows
It is shown：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TDjmax_LFor Diode
Low frequency junction temperature maximums.TDjmin_LFor Diode low frequency junction temperature minimum values.IDLFor Diode low frequency aluminium bonding line current effective values.
The corresponding cycle invalidation period number N of Diode fundamental frequency cyclesDf_FAs follows：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TDjmax_FFor Diode
Fundamental frequency junction temperature maximums.TDjmin_FFor Diode fundamental frequency junction temperature minimum values.IDFFor Diode fundamental frequency aluminium bonding line current effective values.
According to Miner ' s defect theories and formula (23), Diode is in 0-tnThe life consumption CL at momentD(tn) following institute
Show：
In formula, NDsum_LIt is Diode in 0-tnThe low frequency thermal cycle sum at moment.ND_L,αAnd NDf_L,αRespectively Diode α
The corresponding times of thermal cycle of infra-low frequency thermal cycle and cycle invalidation period number.ND_F,ωAnd NDf_F,ωRespectively the ω sampling time
It is spaced the corresponding fundamental frequency times of thermal cycle of T and cycle invalidation period number.N is the total number of sample points until the current time of running.
Diode sampling instants tnThe mean time to failure, MTTF MTTF of corresponding time interval TD(tn) as follows：
In formula, CLD(tn) be Diode in 0-tnThe life consumption at moment.T is sampling time interval.
Diode failure rates λD(tn) as follows：
In formula, MTTFD(tn) it is Diode sampling instants tnThe mean time to failure, MTTF of corresponding time interval T.
Diode reliabilitys RD(tn) as follows：
In formula, λD(tn) it is Diode failure rates.E be natural logrithm function the truth of a matter, about 2.71828..tnWhen to sample
It carves.
3) the mixing MMC capacitors that meter and failure SM voltages are shared are established in the influence according to failure SM to intact SM capacitances
Reliability Evaluation Model.
Further, the key step for establishing mixing MMC capacitor Reliability Evaluation Models is as follows：
3.1) calculable capacitor reliability RC(tn), i.e.,：
In formula, λcFor capacitor faults rate.Ws0For original state.WsiFor the corresponding self-healing energy of i SM failure.tnTo adopt
The sample moment.
Self-healing energy WsiAs follows：
UCiFor the corresponding condenser voltage of i SM failure.RCFor film resistor.C is capacitance.F (P) is interlayer pressure phase
Close function.kcTo calculate the related coefficient of self-healing energy.A is capacitor related coefficient.B is resistance related coefficient.
3.2) according to capacitor reliability RC(tn) mixing MMC capacitor reliabilities are assessed.
4) analysis mixing MMC device loss distribution mixes MMC operational reliabilitys to establish meter and the multi-mode improvement of SM
Assessment models.
Further, the key step for establishing meter and the multi-mode mixing MMC operation reliability evaluation models of SM is as follows：
4.1) SM multimode reliabilitys are calculated.The SM main circuits are made of IGBT, Diode and capacitor.
According to the syntagmatic of IGBT, Diode in SM and capacitor, CSSM reliabilitys R under serviceable conditionCSu(tn) as follows
It is shown：
RCSu(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·RT3(tn)·RD3(tn)·RC(tn)。
(30)
In formula, RT1(tn)、RT2(tn) and RT3(tn) be respectively first IGBT, second IGBT and third IGBT can
By degree.RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability.
Rc(tn) it is capacitor reliability.
HBSM reliabilitys R under serviceable conditionHBu(tn) as follows：
RHBu(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·RC(tn)。 (31)
In formula, RT1(tn)、RT2(tn) and RT3(tn) be respectively first IGBT, second IGBT and third IGBT can
By degree.RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability.
Rc(tn) it is capacitor reliability.
The reliability R of CSSM under semifault stateCSp(tn) as follows：
RCSp(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·(1-RT3(tn)·RD3(tn))·RC(tn)。
(32)
In formula, RT1(tn)、RT2(tn) and RT3(tn) be respectively first IGBT, second IGBT and third IGBT can
By degree.RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability.
Rc(tn) it is capacitor reliability.
4.2) meter and the multi-mode mixing MMC reliabilitys of SM are calculated
The reliability of bridge arm is broadly divided into two kinds of situations.
The first situation is：When CSSM and HBSM damage numbers are no more than itself redundant digit, i.e. iCS≤MCS, and iHB≤
MHBWhen, mix MMC normal operations.
According to bi-distribution new probability formula, when the first situation, the total CSSM reliabilitys R of upper bridge armCSs1(tn) following institute
Show：
In formula, NCSFor the base value of CSSM.RCSu(tn) it is CSSM reliabilitys under serviceable condition.icsFor the damage number of CSSM.
MCSFor the redundant digit of CSSM.
When the first situation, the total HBSM reliabilitys R of upper bridge armHBs1(tn) as follows：
In formula, NHBFor the base value of HBSM.RHBu(tn) it is HBSM reliabilitys under serviceable condition.iHBFor the damage number of HBSM.
MHBFor the redundant digit of HBSM.
Based on the series relationship of each CSSM and HBSM in bridge arm, single-phase upper bridge arm reliability R in the case of the firstArm_u1
(tn) as follows：
RArm_u1(tn)=RCSs1(tn)·RHBs1(tn)。 (35)
In formula, RHBs1(tn) it is the HBSM reliabilitys that upper bridge arm is total in the case of the first.RCSs1(tn) in the case of the first
The total CSSM reliabilitys of upper bridge arm.
The second situation is：It is no more than itself redundant digit when CSSM damages number, and HBSM damage numbers are more than itself redundant digit,
And intact and semifault CSSM is replaced when damaging HBSM, i.e. iCS≤MCS, and MHB<iHB≤MHB+MCS-(iCS-iCSp) when, mix MMC
Normal operation.iCSpFor CSSM semifault numbers.
According to multinomial distribution new probability formula, the total CSSM reliabilitys R of upper bridge armCSs2(tn) as follows：
In formula, iCSpFor CSSM semifault numbers.NCSFor the base value of CSSM.RCSu(tn) it is that CSSM is reliable under serviceable condition
Degree.icsFor the damage number of CSSM.McsFor the redundant digit of CSSM.RCSp(tn) be semifault state CSSM reliability.
Based on each HBSM series relationships in bridge arm, according to bi-distribution new probability formula, the total HBSM reliabilitys of upper bridge arm
RHBs2(tn) as follows：
In formula, iCSpFor CSSM semifault numbers.icsFor the damage number of CSSM.NHBFor the base value of HBSM.RHBu(tn)It is intact
HBSM reliabilitys under state.iHBFor the damage number of HBSM.MHBFor the redundant digit of HBSM.
Based on the series relationship of each CSSM and HBSM in bridge arm, under the second situation under single-phase upper bridge arm reliability RArm_u2
(tn) as follows：
RArm_u2(tn)=RCSs2(tn)·RHBs2(tn)。 (38)
In formula, RHBs2(tn) it is the HBSM reliabilitys that upper bridge arm is total under the second situation.RCSs2(tn) it is under the second situation
The total CSSM reliabilitys of upper bridge arm.
Single-phase upper bridge arm Reliability Function RArm_u(tn)As follows：
RArm_u(tn)=RArm_u1(tn)+RArm_u2(tn)。 (39)
In formula, RArm_u1(tn) it is single-phase upper bridge arm reliability in the case of the first.RArm_u2(tn) place an order for the second situation
Bridge arm reliability in phase.
The series relationship of symmetry and each bridge arm based on mixing MMC, mixing MMC reliability R (tn) as follows：
R(tn)=RArm_u(tn)6。 (40)
In formula, RArm_u(tn) it is single-phase upper bridge arm Reliability Function.
A kind of method of improvement mixing MMC operation reliability evaluation model of the use based on Multiple Time Scales thermal damage, it is main
Include the following steps：
I) the input data in improving mixing MMC operation reliability evaluation models.The data include mainly environmental parameter
With mixing MMC and wind turbine electric parameter.The environmental parameter includes mainly wind speedAnd temperatureMix MMC and wind turbine electricity
Gas parameter includes mainly switching frequency fsw, minimum incision wind speed, maximum excision wind speed, rated wind speed etc., mixing MMC have DC side
Rated voltage, exchange side rated voltage, power factor (PF), modulation ratio and duty ratio.
II) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device loss.I.e.
Calculate sampling instant tnIn corresponding time interval T, IGBT switch periods average loss PT,avgIt is average with the switch periods of Diode
P is lostD,avg。
III) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device more times
Scale junction temperature.
Calculate sampling instant tnIn corresponding time interval T, IGBT fundamental frequency cycles junction temperature mean values TTjavg_F, maximum value
TTjmax_F, minimum value TTjmin_FWith aluminium bonding line current effective value IF.According to rain flow algorithm, 0-t is calculatednLow frequency week at moment IGBT
Phase junction temperature curve maximum of TTjmax_L, minimum value TTjmin_LWith aluminium bonding line current effective value IL。
IV) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device meter and it is more when
Between scale life consumption, mean time to failure, MTTF and failure rate.
Calculate IGBT low frequency cycle invalidation period numbers NTf_LWith fundamental frequency cycle invalidation period number NTf_F, exist to obtain IGBT
0-tnThe life consumption CL at momentT(tn), sampling instant tnThe mean time to failure, MTTF MTTF of corresponding time interval TT(tn), failure rate
λT(tn) and reliability RT(tn)。
Calculate Diode low frequency cycle invalidation period numbers NDf_LWith fundamental frequency cycle invalidation period number NDf_F, to obtain Diode
In 0-tnThe life consumption CL at momentD(tn), sampling instant tnThe mean time to failure, MTTF MTTF of corresponding time interval TD(tn), failure
Rate λD(tn) and reliability RD(tn)。
V) according to input data, the improvement mixing MMC operation reliability evaluation model calculable capacitor reliabilitys RC
(tn)。
VI) according to input data, the improvement mixing MMC operation reliability evaluation models calculate meter and SM is multi-mode mixed
Close MMC reliability R (tn), to assess improving mixing MMC reliabilities of operation.
The solution have the advantages that unquestionable.The present invention focuses on the reliability and wind speed, gas of research mixing MMC
Coupled relation between temperature and inside electric appliance parameter has considered wind speed, gas from the failure mechanism of device
The influence of the environmental factors such as temperature, power frequency and electric parameter to mixing MMC operational reliabilitys, can effectively reflect environmental factor and equipment
Influence of the internal electric parameter to mixing MMC operational reliabilitys.The present invention by mix MMC operational reliability and environmental factor,
Electric parameter couples, and on the basis of loss, and from operation angle, the topology of optimization mixing MMC accurately portrays mixing MMC
Operational reliability and environmental factor and electric parameter relationship, the operational reliability for promoting mixing MMC is horizontal.The present invention is based on
MMC operation characteristics are mixed, for the problem that the serious unevenness of distribution is lost of SM in mixed MMC, propose arranging for failure SM re-usings
It applies, improves the utilization rate of SM in mixing MMC, achieve the effect that promote mixing MMC operational reliabilitys.The present invention can extensive use
In the operation reliability evaluation that the regenerative resources such as wind-powered electricity generation transmit grid-connected middle mixing MMC.
Description of the drawings
Fig. 1 is mixing MMC topology diagrams；
Fig. 2 is HBSM topological structures；
Fig. 3 is CSSM topological structures；
Fig. 4 is wind speed annual data curve；
Fig. 5 is temperature annual data curve；
Fig. 6 is to improve front and back mixing MMC reliability curves；
Fig. 7 is mixing MMC reliability curves；
Fig. 8 is SM bathtub curves；
Fig. 9 is the variation curved surface for mixing MMC reliabilitys with switching frequency and time.
Specific implementation mode
With reference to embodiment, the invention will be further described, but should not be construed the above-mentioned subject area of the present invention only
It is limited to following embodiments.Without departing from the idea case in the present invention described above, according to ordinary skill knowledge and used
With means, various replacements and change are made, should all include within the scope of the present invention.
Embodiment 1：
A kind of improvement mixing MMC operation reliability evaluation models based on Multiple Time Scales thermal damage include mainly following
Step：
1) real time data of wind-powered electricity generation Transmission system is obtained.The real time data includes mainly that wind speed, temperature and equipment are electrical
Parameter.
2) mixing MMC work(is established using mixing MMC operation characteristics and Miner ' s defect theories according to the initial data
Rate device reliability assessment models.The power device of the wind-powered electricity generation Transmission system mainly include insulated gate bipolar crystal IGBT and
Crystal diode Diode.
Further, mixing MMC topological structures include mainly three a, b, c, tri- phase elements.
A phase elements are sequentially connected in series NCSA CSSM modules and NHBA HBSM modules.
B phase elements are sequentially connected in series NCSA CSSM modules and NHBA HBSM modules.
C phase elements are sequentially connected in series NCSA CSSM modules and NHBA HBSM modules.
HBSM is made of power module T1, T2 and capacitance C.
CSSM is made of power module T1, T2, T3 and capacitance C.
Preferably, MMC topological structures can be that upper and lower bridge arm is respectively composed in series by N number of submodule and 1 bridge arm reactance L,
Wherein, SM is made of 2 switching devices and 1 storage capacitor.Each SM can be at 3 kinds of input, excision and locking working conditions.
Further, the key step for establishing the mixing MMC power device Reliability Evaluation Models is as follows：
2.1) mixing MMC power device Multiple Time Scales junction temperatures are calculated.Key step is as follows：
2.1.1 wind-powered electricity generation Transmission system wind turbine output power P) is determinedWToutWith sampling instant tnCorresponding wind speedRelationship.
I-th of wind turbine output power P of wind-powered electricity generation Transmission systemWTout,iWith sampling instant tnCorresponding wind speedThe following institute of relationship
Show：
In formula, PratedFor wind turbine rated power.Vcutin、VratedAnd VcutoutIt respectively cuts wind speed, rated wind speed and cuts
Go out wind speed.kpIt indicates and atmospheric density and the relevant coefficient of wind turbine area.NWTFor wind turbine sum in wind-powered electricity generation Transmission system.N be to
Total number of sample points until the current time of running.tnFor sampling instant.For wind speed.I is arbitrary wind turbine.I=1 ..., NWT。
Mix the transmission power P of MMCMMCoutAs follows：
In formula, NWTFor wind turbine sum in wind-powered electricity generation Transmission system.I is arbitrary wind turbine.I=1 ..., NWT。PWTout,iIt is i-th
Wind turbine output power.
2.1.2) according to formula 1, mixing MMC bridge arm currents are calculated.
Bridge arm current I in A phasesauWith A phase lower bridge arm electric currents IadIt is as follows respectively：
In formula, IdcFor DC side electric current.ImFor ac-side current peak value.For power-factor angle.f0For fundamental frequency.
DC side electric current IdcAs follows：
In formula, UdcFor DC voltage.PMMCoutTo mix the transmission power of MMC.
Ac-side current peak ImAs follows：
In formula, PMMCoutTo mix the transmission power of MMC.For power-factor angle.UacFor exchange side voltage effective value.
2.1.3 j-th of switch periods average loss of bridge arm IGBT in A phases) is calculated.
J-th of switch periods average loss of bridge arm IGBT in A phasesAs follows：
In formula, Rce、UceoAnd τTRespectively IGBT forward conductions resistance, threshold voltage and duty ratio.aT、bTAnd cTFor IGBT
Dynamic characteristic fitting parameter.UratedFor IGBT rated voltages.fswAnd ρTThe respectively switching frequency of IGBT and temperature coefficient.
J is arbitrary switch periods.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.IauFor bridge arm current in A phases.
UdcFor DC voltage.
Switch periods number nswAs follows：
nsw=fsw/f0。 (7)
In formula, fswFor the switching frequency of IGBT.f0For fundamental frequency.
2.1.4 j-th of switch periods average loss of Diode) is calculated
J-th of switch periods average loss of DiodeAs follows：
In formula：Rd、UdAnd τDRespectively Diode forward conductions resistance, threshold voltage and duty ratio.aD、bDAnd cDFor Diode
Dynamic characteristic fitting parameter.UDFor Diode rated voltages.fdwAnd ρDThe respectively switching frequency of Diode and temperature coefficient.
IauFor bridge arm current in A phases.UdcFor DC voltage.
2.1.5 the junction temperature of j-th of switch periods of IGBT in mixing MMC) is calculatedMixing MMC power devices loss causes
Device junction temperature increases, and power module junction temperature can be effectively calculated by building foster ther mal networks model.
According to foster ther mal network models, the junction temperatureAs follows：
In formula,For sampling instant tnCorresponding temperature.For j-th of switch periods IGBT knot-shell heat of r ranks
The temperature difference of RC parallel units in network.R indicates arbitrary order.R=1,2,3,4.For j-th of switch periods IGBT shells-heat dissipation
The temperature difference of RC parallel units in piece ther mal network.For RC in j-th of switch periods IGBT cooling fins-environment ther mal network and receipts or other documents in duplicate
The temperature difference of member.J is arbitrary switch periods.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.
The temperature difference of RC parallel units in j-th of switch periods IGBT knots-shell network of r ranksAs follows：
In formula, RTjc,rFor thermal resistance.τTjc,rFor thermal resistance RTjc,rThermal time constant.TswFor switch periods.It is r ranks
- 1 switch periods IGBT knots-shell ther mal network of jth in RC parallel units the temperature difference.E is the truth of a matter of natural logrithm function, about
2.71828。。For j-th of switch periods average loss of bridge arm IGBT in A phases.J is arbitrary switch periods.J=1 ..., nsw。
nswFor switch periods sum in a fundamental frequency cycles.
The temperature difference of RC parallel units in j-th of switch periods IGBT shells-cooling fin networkAs follows：
In formula, RTchFor thermal resistance.τTchFor thermal resistance RTchThermal time constant.TswFor switch periods.It is that jth -1 is opened
Close the temperature difference of RC parallel units in period IGBT shell-cooling fin ther mal network.E is the truth of a matter of natural logrithm function, about
2.71828。。For j-th of switch periods average loss of bridge arm IGBT in A phases.J is arbitrary switch periods.J=1 ..., nsw。
nswFor switch periods sum in a fundamental frequency cycles.
J-th of switch periods IGBT is the temperature difference of RC parallel units in cooling fin-environment networkAs follows：
In formula, RhaFor thermal resistance.τhaFor thermal resistance RhaThermal time constant.TswFor switch periods.It is that jth -1 is opened
Close the period temperature difference of RC parallel units in IGBT ther mal networks.J is arbitrary switch periods.J=1 ..., nsw。nswFor a fundamental frequency week
Switch periods sum in phase.For j-th of switch periods average loss of bridge arm IGBT in A phases.For bridge arm in A phases
J-th of switch periods average loss of Diode.
The electric parameters such as the power frequency due to different switch periods are different, and are reflected in the fundamental frequency junction temperature of short-term time scale
In.0-tnMoment contains n sampling time interval T, wherein tnThere is N in corresponding sampling time interval TT_FA fundamental frequency cycles (NT_F
=T × f0), i-th fundamental frequency cycles (i=1 ..., NT_F) in, using the RC parallel units temperature difference as iteration variable, obtain fundamental frequency week
Phase junction temperature curve, and then obtain the corresponding junction temperature mean value T of the fundamental frequency cyclesTjavg_F, maximum of TTjmax_F, minimum value TTjmin_FWith
Aluminium bonding line current effective value IF, it is used for IGBT fundamental frequency time scale reliability assessments.Assuming that wind in a sampling time interval T
Speed and temperature are constant, then this NT_FThe T of a fundamental frequency cyclesTjavg_F、TTjmax_F、TTjmin_FAnd IFIt is identical, therefore, extract a base
Frequency period junction temperature parameter.
The wind speed and temperature of different sampling stages interval T is different, and is reflected in the low frequency junction temperature of long time scale.Root
According to 0-tnThe fundamental frequency junction temperature mean value T of moment each sampling time interval TTjavg_F, N is obtained by rain flow algorithmTsum_LA low-frequency cycle
Junction temperature curve, and then obtain the g articles low-frequency cycle junction temperature curve (g=1 ..., NTsum_L) corresponding junction temperature maximums TTjmax_L、
Minimum value TTjmin_LWith aluminium bonding line current effective value IL, it is used for IGBT frequency temporal scale reliability assessments.
2.1.6 the junction temperature of j-th of switch periods of Diode in mixing MMC) is calculated
The junction temperatureAs follows：
In formula,For sampling instant tnCorresponding temperature.For j-th of switch periods Diode knot-shell heat of r ranks
The temperature difference of RC parallel units in network.R indicates arbitrary order.R=1,2,3,4.For j-th of switch periods Diode shells-heat dissipation
The temperature difference of RC parallel units in piece ther mal network.For RC in j-th of switch periods IGBT cooling fins-environment ther mal network and receipts or other documents in duplicate
The temperature difference of member.J is arbitrary switch periods.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.Due to j-th
The temperature difference of RC parallel units and j-th of switch periods Diode cooling fins-ring in switch periods IGBT cooling fins-environment ther mal network
The temperature difference numerically equal of RC parallel units in the ther mal network of border, step, is calculating Diode junction temperatures to simplify the calculationWhen, it can
Directly use the temperature difference
The temperature difference of RC parallel units in j-th of switch periods Diode knots-shell networkAs follows：
In formula, RDjc,rFor thermal resistance.τDjc,rFor thermal resistance RDjc,rThermal time constant.TdwFor switch periods.It is jth -1
The temperature difference of RC parallel units in a switch periods Diode knots-shell ther mal network.J is arbitrary switch periods.J=1 ..., nsw。nswFor
Switch periods sum in one fundamental frequency cycles.For j-th of switch periods average loss of bridge arm Diode in A phases.
The temperature difference of RC parallel units in j-th of switch periods Diode shells-cooling fin networkAs follows：
In formula, RDchFor thermal resistance.τDchFor thermal resistance RDchThermal time constant.TswFor switch periods.It is that jth -1 is opened
Close the temperature difference of RC parallel units in period Diode shell-cooling fin ther mal network.Week is switched for bridge arm Diode in A phases j-th
Phase average loss.J=1 ..., nsw。nswFor switch periods sum in a fundamental frequency cycles.
2.2) MMC power device Multiple Time Scales reliability assessments are mixed.In mixing MMC power device reliability assessments
In, the low frequency junction temperature and fundamental frequency junction temperature of the present embodiment meter and power device quantify the environmental factors such as wind speed, temperature and power frequency etc.
Influence of the electric parameter to power device reliability, to improve its reliability assessment precision.
Key step is as follows：
2.2.1 IGBT low-frequency cycles corresponding cycle invalidation period number N) is calculatedTf_L.Recycle invalidation period number NTf_LIt is as follows
It is shown：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TTjmax_LFor IGBT
Low frequency junction temperature maximums.TTjmin_LFor IGBT low frequency junction temperature minimum values.ILFor IGBT low frequency aluminium bonding line current effective values.E is certainly
The truth of a matter of right logarithmic function, about 2.71828..
The corresponding cycle invalidation period number N of IGBT fundamental frequency cyclesTf_FAs follows：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TTjmax_FFor IGBT
Fundamental frequency junction temperature maximums.TTjmin_FFor IGBT fundamental frequency junction temperature minimum values.IFFor IGBT fundamental frequency aluminium bonding line current effective values.E is certainly
The truth of a matter of right logarithmic function, about 2.71828..
According to Miner ' s defect theories and formula (17), IGBT is in 0-tnThe life consumption CL at momentT(tn) as follows：
In formula, NTsum_LFor 0-tnMoment low frequency thermal cycle sum.NT_L,gAnd NTf_L,gRespectively IGBT g infra-low frequency heat is followed
The corresponding times of thermal cycle of ring and cycle invalidation period number.NT_F,qAnd NTf_F,qRespectively T pairs of sampling time intervals of q-th of IGBT
The fundamental frequency times of thermal cycle and cycle invalidation period number answered.N is the total number of sample points until the current time of running.NTsum_LFor
Low frequency thermal cycle sum.
Preferably, Miner ' s defect theories mainly need to damage caused by calculating a cycle, N under constant amplitude loadTsum_L
It is damaged caused by a cycle, N under variable amplitude loadingTsum_LDamage caused by a cycle.
IGBT sampling instants tnThe mean time to failure, MTTF MTTF of corresponding time interval TT(tn) as follows：
In formula, CLT(tn) be IGBT in 0-tnThe life consumption at moment.T is sampling time interval.
IGBT failure rates λT(tn) as follows：
In formula, MTTFT(tn) it is IGBT sampling instants tnThe mean time to failure, MTTF of corresponding time interval T.
IGBT reliabilitys RT(tn) as follows：
In formula, λT(tn) it is IGBT failure rates.tnFor sampling instant.
2.2.2 Diode low-frequency cycles corresponding cycle invalidation period number N) is calculatedDf_L.Recycle invalidation period number NDf_LIt is as follows
It is shown：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TDjmax_LFor Diode
Low frequency junction temperature maximums.TDjmin_LFor Diode low frequency junction temperature minimum values.IDLFor Diode low frequency aluminium bonding line current effective values.
The corresponding cycle invalidation period number N of Diode fundamental frequency cyclesDf_FAs follows：
In formula, tonFor heating time.U is 0.01 times of module blocking voltage.D is the diameter of aluminium bonding line.K=9.3 ×
1014。β1=-4.416.β2=1285.β3=-0.463.β4=-0.716.β5=-0.761.β6=-0.5.TDjmax_FFor Diode
Fundamental frequency junction temperature maximums.TDjmin_FFor Diode fundamental frequency junction temperature minimum values.IDFFor Diode fundamental frequency aluminium bonding line current effective values.
According to Miner ' s defect theories and formula (23), Diode is in 0-tnThe life consumption CL at momentD(tn) following institute
Show：
In formula, NDsum_LIt is Diode in 0-tnThe low frequency thermal cycle sum at moment.ND_L,αAnd NDf_L,αRespectively Diode α
The corresponding times of thermal cycle of infra-low frequency thermal cycle and cycle invalidation period number.ND_F,ωAnd NDf_F,ωRespectively the ω sampling time
It is spaced the corresponding fundamental frequency times of thermal cycle of T and cycle invalidation period number.N is the total number of sample points until the current time of running.
Diode sampling instants tnThe mean time to failure, MTTF MTTF of corresponding time interval TD(tn) as follows：
In formula, CLD(tn) be Diode in 0-tnThe life consumption at moment.T is sampling time interval.
Diode failure rates λD(tn) as follows：
In formula, MTTFD(tn) it is Diode sampling instants tnThe mean time to failure, MTTF of corresponding time interval T.
Diode reliabilitys RD(tn) as follows：
In formula, λD(tn) it is Diode failure rates.E be natural logrithm function the truth of a matter, about 2.71828..tnWhen to sample
It carves.
3) the mixing MMC capacitors that meter and failure SM voltages are shared are established in the influence according to failure SM to intact SM capacitances
Reliability Evaluation Model.
Further, the key step for establishing mixing MMC capacitor Reliability Evaluation Models is as follows：
3.1) calculable capacitor reliability RC(tn), i.e.,：
In formula, λcFor capacitor faults rate.Ws0For original state.WsiFor the corresponding self-healing energy of i SM failure.tnTo adopt
The sample moment.
Self-healing energy WsiAs follows：
UCiFor the corresponding condenser voltage of i SM failure.RCFor film resistor.C is capacitance.F (P) is interlayer pressure phase
Close function.kcTo calculate the related coefficient of self-healing energy.A is capacitor related coefficient.B is resistance related coefficient.
3.2) according to capacitor reliability RC(tn) mixing MMC capacitor reliabilities are assessed.
4) analysis mixing MMC device loss distribution mixes MMC operational reliabilitys to establish meter and the multi-mode improvement of SM
Assessment models.
Mixing MMC main circuits are made of tri- phase elements of a, b and c, per being mutually divided into upper and lower two bridge arms, each bridge arm by
Multiple SM are in series.To take into account cost, the SM in each bridge arm includes half-bridge SM (HBSM) and passes through energy with DC Line Fault
The SM of power, the present invention select single clamp SM (CSSM) as the SM with DC Line Fault ride-through capability.Both SM main circuits are equal
It is made of IGBT, diode (Diode) and capacitor.Meanwhile MMC reliabilities are mixed to be promoted, include redundancy in each bridge arm
For SM as spare, the present embodiment is spare using the active of generally use in practice.
Further, the key step for establishing meter and the multi-mode mixing MMC operation reliability evaluation models of SM is as follows：
4.1) SM multimode reliabilitys are calculated.The SM main circuits are made of IGBT, Diode and capacitor.
According to the syntagmatic of IGBT, Diode in SM and capacitor, CSSM reliabilitys R under serviceable conditionCSu(tn) as follows
It is shown：
RCSu(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·RT3(tn)·RD3(tn)·RC(tn)。
(30)
In formula, RT1(tn)、RT2(tn) and RT3(tn) be respectively first IGBT, second IGBT and third IGBT can
By degree.RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability.
Rc(tn) it is capacitor reliability.
HBSM reliabilitys R under serviceable conditionHBu(tn) as follows：
RHBu(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·RC(tn)。 (31)
In formula, RT1(tn)、RT2(tn) and RT3(tn) be respectively first IGBT, second IGBT and third IGBT can
By degree.RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability.
Rc(tn) it is capacitor reliability.
Not to T3Before module increases by-pass switch, work as T3And D3In any device failure when, entire CSSM is considered as hair
Raw failure is simultaneously out of service immediately.
If at this time to T3Module carries out bypass processing, and CSSM can be made to be in the semifault state of maintenance voltage support function,
It is continued to run with to be equivalent to HBSM, and then promotes CSSM utilization rates.
The reliability R of CSSM under semifault stateCSp(tn) as follows：
RCSp(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·(1-RT3(tn)·RD3(tn))·RC(tn)。
(32)
In formula, RT1(tn)、RT2(tn) and RT3(tn) be respectively first IGBT, second IGBT and third IGBT can
By degree.RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability.
Rc(tn) it is capacitor reliability.
4.2) meter and the multi-mode mixing MMC reliabilitys of SM are calculated
Mixing MMC bridge arms are connected in series by numerous CSSM and HBSM.
Since intact and semifault CSSM can be equivalent to HBSM, maintenance voltage support function, when HBSM damage numbers are excessive
When, there are intact and semifault CSSM to replace the case where damaging HBSM, and mixing MMC is made to keep normal operation.
Therefore, bridge arm reliability can be divided into two kinds of situations, by taking single-phase upper bridge arm reliability as an example：
The reliability of single-phase upper bridge arm is broadly divided into two kinds of situations.
The first situation is：When CSSM and HBSM damage numbers are no more than itself redundant digit, i.e. iCS≤MCS, and iHB≤
MHBWhen, mix MMC normal operations.
According to bi-distribution new probability formula, when the first situation, the total CSSM reliabilitys R of upper bridge armCSs1(tn) following institute
Show：
In formula, NCSFor the base value of CSSM.RCSu(tn) it is CSSM reliabilitys under serviceable condition.icsFor the damage number of CSSM.
MCSFor the redundant digit of CSSM.
When the first situation, the total HBSM reliabilitys R of upper bridge armHBs1(tn) as follows：
In formula, NHBFor the base value of HBSM.RHBu(tn) it is HBSM reliabilitys under serviceable condition.iHBFor the damage number of HBSM.
MHBFor the redundant digit of HBSM.
Based on the series relationship of each CSSM and HBSM in bridge arm, single-phase upper bridge arm reliability R in the case of the firstArm_u1
(tn) as follows：
RArm_u1(tn)=RCSs1(tn)·RHBs1(tn)。 (35)
In formula, RHBs1(tn) it is the HBSM reliabilitys that upper bridge arm is total in the case of the first.RCSs1(tn) in the case of the first
The total CSSM reliabilitys of upper bridge arm.
The second situation is：It is no more than itself redundant digit when CSSM damages number, and HBSM damage numbers are more than itself redundant digit,
And intact and semifault CSSM is replaced when damaging HBSM, i.e. iCS≤MCS, and MHB<iHB≤MHB+MCS-(iCS-iCSp) when, mix MMC
Normal operation.iCSpFor CSSM semifault numbers.
According to multinomial distribution new probability formula, the total CSSM reliabilitys R of upper bridge armCSs2(tn) as follows：
In formula, iCSpFor CSSM semifault numbers.NCSFor the base value of CSSM.RCSu(tn) it is that CSSM is reliable under serviceable condition
Degree.icsFor the damage number of CSSM.McsFor the redundant digit of CSSM.RCSp(tn) be semifault state CSSM reliability.
Based on each HBSM series relationships in bridge arm, according to bi-distribution new probability formula, the total HBSM reliabilitys of upper bridge arm
RHBs2(tn) as follows：
In formula, iCSpFor CSSM semifault numbers.icsFor the damage number of CSSM.NHBFor the base value of HBSM.RHBu(tn)It is intact
HBSM reliabilitys under state.iHBFor the damage number of HBSM.MHBFor the redundant digit of HBSM.
Based on the series relationship of each CSSM and HBSM in bridge arm, under the second situation under single-phase upper bridge arm reliability RArm_u2
(tn) as follows：
RArm_u2(tn)=RCSs2(tn)·RHBs2(tn)。 (38)
In formula, RHBs2(tn) it is the HBSM reliabilitys that upper bridge arm is total under the second situation.RCSs2(tn) it is under the second situation
The total CSSM reliabilitys of upper bridge arm.
Single-phase upper bridge arm Reliability Function RArm_u(tn)As follows：
RArm_u(tn)=RArm_u1(tn)+RArm_u2(tn)。 (39)
In formula, RArm_u1(tn) it is single-phase upper bridge arm reliability in the case of the first.RArm_u2(tn) place an order for the second situation
Bridge arm reliability in phase.
The series relationship of symmetry and each bridge arm based on mixing MMC, mixing MMC reliability R (tn) as follows：
R(tn)=RArm_u(tn)6。 (40)
In formula, RArm_u(tn) it is single-phase upper bridge arm Reliability Function.
Embodiment 2：
A kind of method of improvement mixing MMC operation reliability evaluation model of the use based on Multiple Time Scales thermal damage, it is main
Include the following steps：
1) input data in improving mixing MMC operation reliability evaluation models.The data include mainly environmental parameter
With mixing MMC and wind turbine electric parameter.
The environmental parameter includes mainly wind speedAnd temperatureIt includes switch to mix MMC and wind turbine electric parameter mainly
Frequency fsw, minimum incision wind speed, maximum excision wind speed, rated wind speed etc., mixing MMC have DC side rated voltage, exchange side volume
Constant voltage, power factor (PF), modulation ratio and duty ratio etc..
2) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device loss.
Calculate sampling instant tnIn corresponding time interval T, IGBT switch periods average loss PT,avgWith opening for Diode
Close period average loss PD,avg。
3) according to input data, the improvement mixing MMC operation reliability evaluation models calculate the more time rulers of power device
Spend junction temperature.
Calculate sampling instant tnIn corresponding time interval T, IGBT fundamental frequency cycles junction temperature mean values TTjavg_F, maximum value
TTjmax_F, minimum value TTjmin_FWith aluminium bonding line current effective value IF。
According to rain flow algorithm, 0-t is calculatednLow-frequency cycle at moment IGBT junction temperature curve maximum of TTjmax_L, minimum value TTjmin_L
With aluminium bonding line current effective value IL。
4) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device meter and it is more when
Between scale life consumption, mean time to failure, MTTF and failure rate.
Calculate IGBT low frequency cycle invalidation period numbers NTf_LWith fundamental frequency cycle invalidation period number NTf_F, exist to obtain IGBT
0-tnThe life consumption CL at momentT(tn), sampling instant tnThe mean time to failure, MTTF MTTF of corresponding time interval TT(tn), failure rate
λT(tn) and reliability RT(tn)。
Calculate Diode low frequency cycle invalidation period numbers NDf_LWith fundamental frequency cycle invalidation period number NDf_F, to obtain Diode
In 0-tnThe life consumption CL at momentD(tn), sampling instant tnThe mean time to failure, MTTF MTTF of corresponding time interval TD(tn), failure
Rate λD(tn) and reliability RD(tn)。
5) according to input data, the improvement mixing MMC operation reliability evaluation model calculable capacitor reliabilitys RC
(tn)。
6) according to input data, the improvement mixing MMC operation reliability evaluation models calculate meter and SM is multi-mode mixed
Close MMC reliability R (tn), to assess improving mixing MMC reliabilities of operation.
Embodiment 3：
A kind of experiment of improvement mixing MMC operation reliability evaluation model of the verification based on Multiple Time Scales thermal damage, it is main
Include the following steps：
1) experiment parameter is configured.The present embodiment uses the FF1000R17IE4 model power module conducts of Infineon companies
MMC power modules are mixed, as shown in table 1, and as wind power plant and are mixed using Dublin, Ireland wind speed in 2016 and temperature record
The external operating mode for closing MMC assesses mixing MMC operational reliabilitys based on the carried model of the present invention.Wind speed, temperature annual data curve
As shown in Figure 2,3, it mixes MMC and fan parameter is as shown in table 2.
The thermal parameter table of table 1FF1000R17IE4 model power modules
| Parameter | Numerical value |
| System nominal capacity | 400MW |
| Voltage on line side | 220kV |
| DC voltage | 400kV |
| HBSM base values | 137 |
| CSSM base values | 113 |
| Capacitor reference failure rate | 1ⅹ10-8occ/hour |
| Capacitor reference voltage | 1.6kV |
| Output frequency | 50Hz |
| Switching frequency | 2kHz |
| Power factor (PF) | 0.9 |
| Modulation ratio | 0.8 |
| Fan capacity | 2MW |
| Wind turbine quantity | 200 |
| Cut wind speed | 3m/s |
| Rated wind speed | 8.5m/s |
| Cut-out wind speed | 16m/s |
Table 2 mixes MMC and fan parameter
2) mixing MMC power device thermal damages analysis.To verify the more time rulers of mixing MMC power devices proposed by the present invention
The accuracy for spending Reliability Evaluation Model is input with wind speed and temperature annual data, can based on power device proposed by the present invention
By property assessment models, power device low frequency and fundamental frequency year life consumption situation are obtained respectively, is specifically shown in Table 3.
As shown in Table 3, although low frequency life consumption is in T1、T2、T3、D1And D2Middle accounting is larger, but fundamental frequency life consumption accounts for
Than also can not be ignored, in T2、D1And D3Middle accounting respectively reaches 16.39%, 25.06% and 67.82%, especially in D3In, base
Frequency life consumption occupies main status more than low frequency.Therefore, the reliability assessment for only considering low frequency life consumption, the present invention are compared
The Multiple Time Scales Reliability Evaluation Model of structure can integrate meter and environmental factor and electric parameter to mixing MMC power devices
It influences, lays the foundation for equipment operation reliability evaluation.
Table 3 mixes MMC power device year life consumptions
3) corrective measure is to mixing MMC reliability effects
As shown in Table 3, T3And D3The sum of life consumption in CSSM life consumptions accounting be up to 50.08%, be far above it
His device, therefore, T3Module is most fragile.The present invention passes through to failure T3Module carries out short circuit, can make T3The CSSM of module failure
It is equivalent to HBSM, continues to voltage support function, to promote CSSM utilization rates, reaches promotion mixing MMC reliability levels.
It is carried by the verification present invention and improves CSSM to mixing MMC reliability effects, proposed based on conventional model and the present invention
Meter and the multi-mode mixing MMC operation reliability evaluation models of SM, obtain and improve forward and backward mixing MMC reliabilitys R1And R2, tool
Body is shown in shown in Fig. 4 and table 4.
As shown in Figure 4, improved mixing MMC reliabilitys R2More than reliability R before improvement1.As shown in Table 4, MMC is mixed
When running to 15 years, R1And R2Respectively 0.7421 and 0.8838, compare R1, improved mixing MMC reliabilitys R2It improves
19.10%.And when mixing MMC in 20 years, R1And R2Respectively 0.2018 and 0.4978, compare R1, improved mixing MMC
Reliability R2 improves 146.68%.It can be seen that improved mixing MMC reliabilitys are effectively promoted, this hair is demonstrated
The validity of bright carried corrective measure.
| Time/year | Reliability R1 | Reliability R2 | Reliability promotes percentage |
| 5 | 0.9999 | 0.9999 | 0.00% |
| 10 | 0.9861 | 0.9935 | 0.75% |
| 15 | 0.7421 | 0.8838 | 19.10% |
| 20 | 0.2018 | 0.4978 | 146.68% |
| 25 | 0.0113 | 0.1184 | 947.78% |
| 30 | 0 | 0.0096 | — |
Table 4 improves front and back mixing MMC reliability tables
4) MMC operation reliability evaluations are mixed.
To verify the validity of mixing MMC operational reliability models proposed by the present invention, based on proposed by the present invention reliable
Property assessment models, the mixing MMC electric parameters differences such as assessment wind speed, the fluctuation of the environmental factors such as temperature and switching frequency are to mixing
The influence of MMC operational reliabilitys.
4.1) environmental factor is to mixing MMC operational reliability impact analysis.
It is to analyze the environmental factors such as wind speed, temperature to mixing MMC reliability effects, is transported according to mixing MMC proposed in this paper
Row reliability model and conventional Constant Failure Rate model, are run with base value, obtain mixing MMC reliabilitys R respectively1And R2, it is specifically shown in
Shown in Fig. 5.Meanwhile obtaining CSSM and HBSM bathtub curves, specifically as shown in Figure 6.
As shown in Figure 5, mixing the reliability of MMC can be changed by such environmental effects such as wind speed, temperature.Such as Fig. 2
Shown in 6, when mixing MMC runs on 500-1000h, wind speed is higher, concentrates on 7-11m/s, and larger, HBSM is lost in device lifetime
0.9 × 10 is concentrated on CSSM failure rates-6Occ/hour and 1.8 × 10-6Occ/hour, mixing MMC reliabilitys decline very fast.
When mixing MMC runs on 3500-4000h, wind speed is relatively low, concentrates on 1-5m/s, and smaller, HBSM and CSSM is lost in device lifetime
Close to zero, mixing MMC reliabilitys decline slow failure rate.Similarly, as shown in figure 3, during 4000-6000h, temperature is higher,
CSSM and HBSM failure rates are relatively high, and fluctuation tendency is consistent with temperature.Therefore, mixing MMC operational reliabilitys proposed in this paper
Assessment models meet theory expectation.In addition, being also seen that due to R by Fig. 52It does not count and the environmental factors such as wind speed, temperature changes,
When 1000h, 4000h and 7000h, R2With R1Relative error respectively reaches 41.38%, 34.45% and 82.36%, reliability difference
It is larger.Therefore, it is necessary to count and the environmental factors such as wind speed, temperature to mix MMC reliability effects.
4.2) electric parameter is to mixing MMC operational reliability impact analysis.
Mixing MMC operational reliabilitys are influenced for electric parameters such as analysis switching frequencies, are based on mixing proposed by the present invention
MMC operational reliability models obtain mixing MMC reliability situations of change under different switching frequencies, specifically as shown in Figure 7.Table 5 is opened up
MMC reliability operating conditions are mixed when showing 900h under difference switching frequency.
As shown in Figure 7, switching frequency is higher, and mixing MMC reliabilitys decline faster.As shown in Table 5,900h moment, power
When devices switch frequency increases to 3000Hz from 1000Hz, switching loss increases therewith, CSSM and HBSM failure rates is caused to be distinguished
From 6.91 × 10-7Occ/hour and 1.56 × 10-7Occ/hour rises to 2.17 × 10-6Occ/hour and 1.63 × 10-6occ/
Hour, it is final so that mixing MMC reliabilitys drop to 0.2572 by 0.715.Therefore, operation reliability evaluation proposed by the present invention
Model, which can effectively portray switching frequency, influences mixing MMC operational reliabilitys.
MMC operational reliability tables are mixed when 5 900h of table under difference switching frequency
In conclusion proposed by the present invention consider that the mixing MMC operational reliabilitys of Multiple Time Scales cumulative damage effect are commented
Influence of the electric parameters such as the environmental factors such as wind speed, temperature and switch to mixing MMC operational reliabilitys can accurately be portrayed by estimating model,
The reliability that mixing MMC is promoted from operation angle, by building corresponding meter and the multi-mode mixing MMC reliability assessment moulds of SM
Type, it was demonstrated that the reliability level of improved mixing MMC is obviously improved.
Claims (5)
1. a kind of improvement mixing MMC operation reliability evaluation models based on Multiple Time Scales thermal damage, which is characterized in that main
Include the following steps：
1) real time data of wind-powered electricity generation Transmission system is obtained；The real time data includes mainly that the wind speed, temperature and equipment are electrical
Parameter；
2) mixing MMC power devices are established using mixing MMC operation characteristics and Miner ' s defect theories according to the initial data
Part Reliability Evaluation Model；The power device of the wind-powered electricity generation Transmission system includes mainly insulated gate bipolar crystal IGBT and crystal
Diode Diode；
4) it is reliable to establish the mixing MMC capacitors that meter and failure SM voltages are shared for the influence according to failure SM to intact SM capacitances
Property assessment models；
4) analysis mixing MMC device loss distribution mixes MMC operation reliability evaluations to establish meter and the multi-mode improvement of SM
Model.
2. a kind of improvement mixing MMC operation reliability evaluations based on Multiple Time Scales thermal damage according to claim 1
Model, it is characterised in that：The key step for establishing the mixing MMC power device Reliability Evaluation Models is as follows：
1) mixing MMC power device Multiple Time Scales junction temperatures are calculated；Key step is as follows：
1.1) wind-powered electricity generation Transmission system wind turbine output power P is determinedWToutWith sampling instant tnCorresponding wind speedRelationship；
I-th of wind turbine output power P of wind-powered electricity generation Transmission systemWTout,iWith sampling instant tnCorresponding wind speedRelationship it is as follows：
In formula, PratedFor wind turbine rated power；Vcutin、VratedAnd VcutoutIt respectively cuts wind speed, rated wind speed and cuts out wind
Speed；kpIt indicates and atmospheric density and the relevant coefficient of wind turbine area；NWTFor wind turbine sum in wind-powered electricity generation Transmission system；N is to current
Total number of sample points until the time of running；tnFor sampling instant；For wind speed；I is arbitrary wind turbine；I=1 ..., NWT；
Mix the transmission power P of MMCMMCoutAs follows：
In formula, NWTFor wind turbine sum in wind-powered electricity generation Transmission system；I is arbitrary wind turbine；I=1 ..., NWT；PWTout,iFor i-th of wind turbine
Output power；
1.2) according to formula 1, mixing MMC bridge arm currents are calculated；
Bridge arm current I in A phasesauWith A phase lower bridge arm electric currents IadIt is as follows respectively：
In formula, IdcFor DC side electric current；ImFor ac-side current peak value；For power-factor angle；f0For fundamental frequency；
DC side electric current IdcAs follows：
In formula, UdcFor DC voltage；PMMCoutTo mix the transmission power of MMC；
Ac-side current peak ImAs follows：
In formula, PMMCoutTo mix the transmission power of MMC；For power-factor angle；UacFor exchange side voltage effective value；
1.3) j-th of switch periods average loss of bridge arm IGBT in A phases is calculated；
J-th of switch periods average loss of bridge arm IGBT in A phasesAs follows：
In formula, Rce、UceoAnd τTRespectively IGBT forward conductions resistance, threshold voltage and duty ratio；aT、bTAnd cTFor IGBT dynamics
Characteristic curve fitting parameter；UratedFor IGBT rated voltages；fswAnd ρTThe respectively switching frequency of IGBT and temperature coefficient；J is
Arbitrary switch periods；J=1 ..., nsw；nswFor switch periods sum in a fundamental frequency cycles；IauFor bridge arm current in A phases；Udc
For DC voltage；
Switch periods number nswAs follows：
nsw=fsw/f0； (7)
In formula, fswFor the switching frequency of IGBT；f0For fundamental frequency；
1.4) j-th of switch periods average loss of Diode is calculated
J-th of switch periods average loss of DiodeAs follows：
In formula：Rd、UdAnd τDRespectively Diode forward conductions resistance, threshold voltage and duty ratio；aD、bDAnd cDFor Diode dynamics
Characteristic curve fitting parameter；UDFor Diode rated voltages；fdwAnd ρDThe respectively switching frequency of Diode and temperature coefficient；IauFor
Bridge arm current in A phases；UdcFor DC voltage；
1.5) junction temperature of j-th of switch periods of IGBT in mixing MMC is calculated
The junction temperatureAs follows：
In formula,For sampling instant tnCorresponding temperature；For j-th of switch periods IGBT knots-shell ther mal network of r ranks
The temperature difference of middle RC parallel units；R indicates arbitrary order；R=1,2,3,4；For j-th of switch periods IGBT shell-cooling fin heat
The temperature difference of RC parallel units in network；For RC parallel units in j-th of switch periods IGBT cooling fins-environment ther mal network
The temperature difference；J is arbitrary switch periods；J=1 ..., nsw；nswFor switch periods sum in a fundamental frequency cycles；
The temperature difference of RC parallel units in j-th of switch periods IGBT knots-shell network of r ranksAs follows：
In formula, RTjc,rFor thermal resistance；τTjc,rFor thermal resistance RTjc,rThermal time constant；TswFor switch periods；It is the of r ranks
The temperature difference of RC parallel units in j-1 switch periods IGBT knots-shell ther mal network；Week is switched for bridge arm IGBT in A phases j-th
Phase average loss；J is arbitrary switch periods；J=1 ..., nsw；nswFor switch periods sum in a fundamental frequency cycles；
The temperature difference of RC parallel units in j-th of switch periods IGBT shells-cooling fin networkAs follows：
In formula, RTchFor thermal resistance；τTchFor thermal resistance RTchThermal time constant；TswFor switch periods；It is -1 switch week of jth
The temperature difference of RC parallel units in phase IGBT shell-cooling fin ther mal network；It is average for j-th of switch periods of bridge arm IGBT in A phases
Loss；J is arbitrary switch periods；J=1 ..., nsw；nswFor switch periods sum in a fundamental frequency cycles；
J-th of switch periods IGBT is the temperature difference of RC parallel units in cooling fin-environment networkAs follows：
In formula, RhaFor thermal resistance；τhaFor thermal resistance RhaThermal time constant；TswFor switch periods；It is -1 switch of jth
The period temperature difference of RC parallel units in IGBT ther mal networks；J is arbitrary switch periods；J=1 ..., nsw；nswFor a fundamental frequency cycles
Interior switch periods sum；For j-th of switch periods average loss of bridge arm IGBT in A phases；For bridge arm Diode in A phases
J-th of switch periods average loss；
1.6) junction temperature of j-th of switch periods of Diode in mixing MMC is calculated
The junction temperatureAs follows：
In formula,For sampling instant tnCorresponding temperature；For j-th of switch periods Diode knots-shell ther mal network of r ranks
The temperature difference of middle RC parallel units；R indicates arbitrary order；R=1,2,3,4；For j-th of switch periods Diode shell-cooling fin heat
The temperature difference of RC parallel units in network；For RC parallel units in j-th of switch periods IGBT cooling fins-environment ther mal network
The temperature difference；J is arbitrary switch periods；J=1 ..., nsw；nswFor switch periods sum in a fundamental frequency cycles；
The temperature difference of RC parallel units in j-th of switch periods Diode knots-shell networkAs follows：
In formula, RDjc,rFor thermal resistance；τDjc,rFor thermal resistance RDjc,rThermal time constant；TdwFor switch periods；It is that jth -1 is opened
Close the temperature difference of RC parallel units in period Diode knot-shell ther mal network；J is arbitrary switch periods；J=1 ..., nsw；nswIt is one
Switch periods sum in fundamental frequency cycles；For j-th of switch periods average loss of bridge arm Diode in A phases；
The temperature difference of RC parallel units in j-th of switch periods Diode shells-cooling fin networkAs follows：
In formula, RDchFor thermal resistance；τDchFor thermal resistance RDchThermal time constant；TswFor switch periods；It is -1 switch week of jth
The temperature difference of RC parallel units in phase Diode shell-cooling fin ther mal network；It is flat for j-th of switch periods of bridge arm Diode in A phases
It is lost；J=1 ..., nsw；nswFor switch periods sum in a fundamental frequency cycles；
2) MMC power device Multiple Time Scales reliability assessments are mixed；Key step is as follows：
2.1) IGBT low-frequency cycles corresponding cycle invalidation period number N is calculatedTf_L；Recycle invalidation period number NTf_LAs follows：
In formula, tonFor heating time；U is 0.01 times of module blocking voltage；D is the diameter of aluminium bonding line；K=9.3 × 1014；
β1=-4.416；β2=1285；β3=-0.463；β4=-0.716；β5=-0.761；β6=-0.5；TTjmax_LFor IGBT low frequencies
Junction temperature maximums；TTjmin_LFor IGBT low frequency junction temperature minimum values；ILFor IGBT low frequency aluminium bonding line current effective values；
The corresponding cycle invalidation period number N of IGBT fundamental frequency cyclesTf_FAs follows：
In formula, tonFor heating time；U is 0.01 times of module blocking voltage；D is the diameter of aluminium bonding line；K=9.3 × 1014；
β1=-4.416；β2=1285；β3=-0.463；β4=-0.716；β5=-0.761；β6=-0.5；TTjmax_FFor IGBT fundamental frequencies
Junction temperature maximums；TTjmin_FFor IGBT fundamental frequency junction temperature minimum values；IFFor IGBT fundamental frequency aluminium bonding line current effective values；
According to Miner ' s defect theories and formula (17), IGBT is in 0-tnThe life consumption CL at momentT(tn) as follows：
In formula, NTsum_LFor 0-tnMoment low frequency thermal cycle sum；NT_L,gAnd NTf_L,gRespectively IGBT g infra-low frequency thermal cycles pair
The times of thermal cycle and cycle invalidation period number answered；NT_F,qAnd NTf_F,qRespectively q-th of sampling time interval T of IGBT is corresponding
Fundamental frequency times of thermal cycle and cycle invalidation period number；N is the total number of sample points until the current time of running；NTsum_LFor low frequency
Thermal cycle sum；
IGBT sampling instants tnThe mean time to failure, MTTF MTTF of corresponding time interval TT(tn) as follows：
In formula, CLT(tn) be IGBT in 0-tnThe life consumption at moment；T is sampling time interval；
IGBT failure rates λT(tn) as follows：
In formula, MTTFT(tn) it is IGBT sampling instants tnThe mean time to failure, MTTF of corresponding time interval T；
IGBT reliabilitys RT(tn)As follows：
In formula, λT(tn) it is IGBT failure rates；tnFor sampling instant；
2.2) Diode low-frequency cycles corresponding cycle invalidation period number N is calculatedDf_L；Recycle invalidation period number NDf_LAs follows：
In formula, tonFor heating time；U is 0.01 times of module blocking voltage；D is the diameter of aluminium bonding line；K=9.3 × 1014；
β1=-4.416；β2=1285；β3=-0.463；β4=-0.716；β5=-0.761；β6=-0.5；；TDjmax_LIt is low for Diode
Frequency junction temperature maximums；TDjmin_LFor Diode low frequency junction temperature minimum values；IDLFor Diode low frequency aluminium bonding line current effective values；
The corresponding cycle invalidation period number N of Diode fundamental frequency cyclesDf_FAs follows：
In formula, tonFor heating time；U is 0.01 times of module blocking voltage；D is the diameter of aluminium bonding line；K=9.3 × 1014；
β1=-4.416；β2=1285；β3=-0.463；β4=-0.716；β5=-0.761；β6=-0.5；TDjmax_FFor Diode fundamental frequencies
Junction temperature maximums；TDjmin_FFor Diode fundamental frequency junction temperature minimum values；IDFFor Diode fundamental frequency aluminium bonding line current effective values；
According to Miner ' s defect theories and formula (23), Diode is in 0-tnThe life consumption CL at momentD(tn) as follows：
In formula, NDsum_LIt is Diode in 0-tnThe low frequency thermal cycle sum at moment；ND_L,αAnd NDf_L,αRespectively Diode the α times is low
The corresponding times of thermal cycle of frequency thermal cycle and cycle invalidation period number；ND_F,ωAnd NDf_F,ωRespectively the ω sampling time interval
The corresponding fundamental frequency times of thermal cycle of T and cycle invalidation period number；N is the total number of sample points until the current time of running；
Diode sampling instants tnThe mean time to failure, MTTF MTTF of corresponding time interval TD(tn) as follows：
In formula, CLD(tn) be Diode in 0-tnThe life consumption at moment；T is sampling time interval；
Diode failure rates λD(tn) as follows：
In formula, MTTFD(tn) it is Diode sampling instants tnThe mean time to failure, MTTF of corresponding time interval T；
Diode reliabilitys RD(tn) as follows：
In formula, λD(tn) it is Diode failure rates；tnFor sampling instant.
3. a kind of improvement mixing MMC operation reliability evaluations based on Multiple Time Scales thermal damage according to claim 1
Model, it is characterised in that：The key step for establishing mixing MMC capacitor Reliability Evaluation Models is as follows：
1) calculable capacitor reliability RC(tn), i.e.,：
In formula, λcFor capacitor faults rate；Ws0For original state；WsiFor the corresponding self-healing energy of i SM failure；tnWhen to sample
It carves；
Self-healing energy WsiAs follows：
UCiFor the corresponding condenser voltage of i SM failure；RCFor film resistor；C is capacitance；F (P) is interlayer pressure correlation letter
Number；A is capacitor related coefficient；B is resistance related coefficient；kcTo calculate the related coefficient of self-healing energy；
2) according to capacitor reliability RC(tn) mixing MMC capacitor reliabilities are assessed.
4. a kind of improvement mixing MMC operation reliability evaluations based on Multiple Time Scales thermal damage according to claim 1
Model, it is characterised in that：The key step for establishing meter and the multi-mode mixing MMC operation reliability evaluation models of SM is as follows：
1) SM multimode reliabilitys are calculated；The SM main circuits are made of IGBT, Diode and capacitor；
According to the syntagmatic of IGBT, Diode in SM and capacitor, CSSM reliabilitys R under serviceable conditionCSu(tn) as follows：
RCSu(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·RT3(tn)·RD3(tn)·RC(tn)； (30)
In formula, RT1(tn)、RT2(tn) and RT3(tn) it is respectively the reliable of first IGBT, second IGBT and third IGBT
Degree；RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability；Rc
(tn) it is capacitor reliability；
HBSM reliabilitys R under serviceable conditionHBu(tn) as follows：
RHBu(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·RC(tn)； (31)
In formula, RT1(tn)、RT2(tn) and RT3(tn) it is respectively the reliable of first IGBT, second IGBT and third IGBT
Degree；RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability；Rc
(tn) it is capacitor reliability；
The reliability R of CSSM under semifault stateCSp(tn) as follows：
RCSp(tn)=RT1(tn)·RD1(tn)·RT2(tn)·RD2(tn)·(1-RT3(tn)·RD3(tn))·RC(tn)；
(32)
In formula, RT1(tn)、RT2(tn) and RT3(tn) it is respectively the reliable of first IGBT, second IGBT and third IGBT
Degree；RD1(tn)、RD2(tn) and RD3(tn) be respectively first Diode, second Diode and third Diode reliability；Rc
(tn) it is capacitor reliability；
2) meter and the multi-mode mixing MMC reliabilitys of SM are calculated
The reliability of bridge arm is broadly divided into two kinds of situations；
The first situation is：When CSSM and HBSM damage numbers are no more than itself redundant digit, i.e. iCS≤MCS, and iHB≤MHBWhen,
Mix MMC normal operations；
According to bi-distribution new probability formula, when the first situation, the total CSSM reliabilitys R of upper bridge armCSs1(tn) as follows：
In formula, NCSFor the base value of CSSM；RCSu(tn) it is CSSM reliabilitys under serviceable condition；icsFor the damage number of CSSM；MCSFor
The redundant digit of CSSM；
When the first situation, the total HBSM reliabilitys R of upper bridge armHBs1(tn) as follows：
In formula, NHBFor the base value of HBSM；RHBu(tn) it is HBSM reliabilitys under serviceable condition；iHBFor the damage number of HBSM；MHBFor
The redundant digit of HBSM；
Based on the series relationship of each CSSM and HBSM in bridge arm, single-phase upper bridge arm reliability R in the case of the firstArm_u1(tn) as follows
It is shown：
RArm_u1(tn)=RCSs1(tn)·RHBs1(tn)； (35)
In formula, RHBs1(tn) it is the HBSM reliabilitys that upper bridge arm is total in the case of the first；RCSs1(tn) it is upper bridge in the case of the first
The total CSSM reliabilitys of arm；
The second situation is：It is no more than itself redundant digit when CSSM damages number, and HBSM damage numbers are more than itself redundant digit, and it is complete
When good and semifault CSSM replaces damage HBSM, i.e. iCS≤MCS, and MHB<iHB≤MHB+MCS-(iCS-iCSp) when, mixing MMC is normal
Operation；iCSpFor CSSM semifault numbers；
According to multinomial distribution new probability formula, the total CSSM reliabilitys R of upper bridge armCSs2(tn) as follows：
In formula, iCSpFor CSSM semifault numbers；NCSFor the base value of CSSM；RCSu(tn) it is CSSM reliabilitys under serviceable condition；ics
For the damage number of CSSM；McsFor the redundant digit of CSSM；RCSp(tn) be semifault state CSSM reliability；
Based on each HBSM series relationships in bridge arm, according to bi-distribution new probability formula, the total HBSM reliabilitys R of upper bridge armHBs2(tn)
As follows：
In formula, iCSpFor CSSM semifault numbers；icsFor the damage number of CSSM；NHBFor the base value of HBSM；RHBu(tn)For serviceable condition
Lower HBSM reliabilitys；iHBFor the damage number of HBSM；MHBFor the redundant digit of HBSM；
Based on the series relationship of each CSSM and HBSM in bridge arm, under the second situation under single-phase upper bridge arm reliability RArm_u2(tn) such as
Shown in lower：
RArm_u2(tn)=RCSs2(tn)·RHBs2(tn)； (38)
In formula, RHBs2(tn) it is the HBSM reliabilitys that upper bridge arm is total under the second situation；RCSs2(tn) it is upper bridge under the second situation
The total CSSM reliabilitys of arm；
Single-phase upper bridge arm Reliability Function RArm_u(tn)As follows：
RArm_u(tn)=RArm_u1(tn)+RArm_u2(tn)； (39)
In formula, RArm_u1(tn) it is single-phase upper bridge arm reliability in the case of the first；RArm_u2(tn) it is on single-phase under the second situation
Bridge arm reliability；
The series relationship of symmetry and each bridge arm based on mixing MMC, mixing MMC reliability R (tn) as follows：
R(tn)=RArm_u(tn)6； (40)
In formula, RArm_u(tn) it is single-phase upper bridge arm Reliability Function.
5. a kind of improvement mixing MMC based on Multiple Time Scales thermal damage using described in claim 1 to claim 4 is run
The method of Reliability Evaluation Model, which is characterized in that mainly include the following steps that：
1) input data in improving mixing MMC operation reliability evaluation models；The data include mainly environmental parameter and mix
Close MMC and wind turbine electric parameter；The environmental parameter includes mainly wind speedAnd temperatureMix MMC and wind turbine electric parameter
Include mainly switching frequency fsw, minimum incision wind speed, maximum excision wind speed, rated wind speed etc., mixing MMC have the specified electricity of DC side
Pressure, exchange side rated voltage, power factor (PF), modulation ratio and duty ratio；
2) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device loss；It calculates and adopts
Sample moment tnIn corresponding time interval T, IGBT switch periods average loss PT,avgWith the switch periods average loss of Diode
PD,avg；
3) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device Multiple Time Scales knot
Temperature；
Calculate sampling instant tnIn corresponding time interval T, IGBT fundamental frequency cycles junction temperature mean values TTjavg_F, maximum of TTjmax_F, most
Small value TTjmin_FWith aluminium bonding line current effective value IF；According to rain flow algorithm, 0-t is calculatednIGBT moment, junction temperature curve low-frequency cycle
Maximum of TTjmax_L, minimum value TTjmin_LWith aluminium bonding line current effective value IL；
4) according to input data, the improvement mixing MMC operation reliability evaluation models calculate power device meter and more time rulers
Life consumption, mean time to failure, MTTF and the failure rate of degree；
Calculate IGBT low frequency cycle invalidation period numbers NTf_LWith fundamental frequency cycle invalidation period number NTf_F, to obtain IGBT in 0-tn
The life consumption CL at momentT(tn), sampling instant tnThe mean time to failure, MTTF MTTF of corresponding time interval TT(tn), failure rate λT
(tn) and reliability RT(tn)；
Calculate Diode low frequency cycle invalidation period numbers NDf_LWith fundamental frequency cycle invalidation period number NDf_F, to obtain Diode in 0-
tnThe life consumption CL at momentD(tn), sampling instant tnThe mean time to failure, MTTF MTTF of corresponding time interval TD(tn), failure rate λD
(tn) and reliability RD(tn)；
5) according to input data, the improvement mixing MMC operation reliability evaluation model calculable capacitor reliabilitys RC(tn)；
6) according to input data, the improvement mixing MMC operation reliability evaluation models calculate meter and the multi-mode mixing MMC of SM
Reliability R (tn), to assess improving mixing MMC reliabilities of operation.
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| CN109581178A (en) * | 2018-12-21 | 2019-04-05 | 武汉合康电驱动技术有限公司 | Determine the method and apparatus of voltage source inverter IGBT module junction temperature |
| CN109917638A (en) * | 2018-12-05 | 2019-06-21 | 重庆大学 | The MMC dynamic redundancy preventive maintenance method that meter and operating condition influence |
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| CN110880785A (en) * | 2019-11-12 | 2020-03-13 | 东南大学 | Active thermal control method of modular multilevel converter based on hybrid modulation strategy |
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| CN110261698B (en) * | 2019-06-20 | 2021-10-08 | 重庆大学 | Metallized film capacitor reliability evaluation method based on MMC converter valve application working condition |
| CN110880785A (en) * | 2019-11-12 | 2020-03-13 | 东南大学 | Active thermal control method of modular multilevel converter based on hybrid modulation strategy |
| CN110880785B (en) * | 2019-11-12 | 2022-06-17 | 东南大学 | Active thermal control method of modular multilevel converter based on hybrid modulation strategy |
| CN111090940A (en) * | 2019-12-17 | 2020-05-01 | 南方电网科学研究院有限责任公司 | MMC submodule crimping type IGBT short-term failure analysis method based on ANSYS |
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| CN111199101B (en) * | 2019-12-27 | 2022-04-22 | 西安交通大学 | IGBT reliability analysis method based on MMC working condition device level degradation |
| CN111199101A (en) * | 2019-12-27 | 2020-05-26 | 西安交通大学 | IGBT reliability analysis method based on MMC working condition device level degradation |
| CN112084651A (en) * | 2020-09-07 | 2020-12-15 | 武汉大学 | Multi-scale wind power IGBT reliability assessment method and system considering fatigue damage |
| CN112084651B (en) * | 2020-09-07 | 2022-08-26 | 武汉大学 | Multi-scale wind power IGBT reliability assessment method and system considering fatigue damage |
| CN114048908A (en) * | 2021-11-15 | 2022-02-15 | 东北大学 | Multi-time scale strengthening interval optimization method for unified power grid-distributed heat supply network system |
| CN114048908B (en) * | 2021-11-15 | 2024-07-02 | 东北大学 | Multi-time scale reinforcement interval optimization method for unified power grid-distributed heat supply network system |
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