Wind electric converter high voltage crossing control method and device based on Hysteresis controlTechnical field
The present invention relates to wind power generation current-transformation control technology field, a kind of particularly full work(based on hysteretic loop current controlThe high voltage crossing control method and device of rate wind-force generating converter.
Background technology
Wind energy is a kind of clean renewable resource, and wind generating technology develops rapidly in recent years, installed capacity of wind-driven powerPerhaps rapid soaring.Due to large-scale wind power integration, ratio of the wind energy in power grid constantly increases, it is desirable to which wind power generating set hasStandby stronger fault ride-through capacity.Wherein high voltage crossing ability is increasingly taken seriously, and external many countries have gone outPlatform relevant criterion and directive/guide.Domestic corresponding high-voltage ride through of wind power generating set regulation is also in formulation.
When power grid failure causes Wind turbines grid entry point overvoltage occur, if not using special control planSlightly, Wind turbines will be reduced by the active power of net side current transformer feed-in power grid, since wind-driven generator inertia is larger, be led toThe generator-side converter wear injection DC bus active power crossed in wind power unit converter is constant, will finally lead to DC bus-bar voltageLifting.When overvoltage is not serious, unit is possible to direct through fault, but when overvoltage is serious, unit is very likelyOff-grid due to current transformer DC bus-bar voltage is over-pressed or grid-connected current overcurrent.In extreme circumstances, full power convertor is also possible toIt damages.Therefore full power convertor needs, for the special traversing method of electrical network high voltage accident design, to promote unitHigh voltage fail ride-through capability.
Existing related application such as number of patent application is that CN201210581893.4 and CN201620175536.1 is inventedPatent.Wherein application No. is proposing a kind of control method of DC side-discharging circuit in the invention of CN201210581893.4,The invention only proposes the control method of direct-current unloading circuit, does not consider pusher side in wind power system, net side current transformerControl and discharging circuit and pusher side, net side current transformer between Collaborative Control.Application No. is CN201620175536.1'sUtility model proposes a kind of low voltage crossing controller for direct current transportation application scenario, due to wind-powered electricity generation application scenario and directlyStream transmission of electricity occasion low-voltage control in there are larger difference, direct current transportation control targe be avoid when low-voltage is restored byThe overvoltage caused by idle injection, and require current transformer in low voltage crossing whole process that overvoltage cannot occur in wind power systemOr over current fault, and unit is unable to off-grid.The Hysteresis control technology that stagnant ring is all made of in two above patent, but be allHysteresis control based on voltage, application No. is in the invention of CN201210581893.4 using the stagnant ring control of DC bus-bar voltageThe object of technology processed, Hysteresis control is direct-current unloading circuit, and there is no the controls for pusher side, net side current transformer to illustrate.ApplicationNumber for CN201620175536.1 utility model using the Hysteresis control based on network voltage, network voltage is used only toIt carries out stagnant ring cutting between different control models to change, there is no directly inputted using voltage as what power switch controlled.
Invention content
In order to solve the problems, such as that conventional Wind turbines cannot pass through high voltage fail, the present invention proposes a kind of based on stagnant ringThe high voltage crossing control method and device of the total power wind-force generating converter of current control.
To realize that said effect, the technical solution of the application are as follows：
Wind electric converter high voltage crossing control method based on Hysteresis control, it is characterised in that：
It is as follows：
The three-phase voltage for measuring power grid in real time carries out positive-negative sequence separation to network voltage, calculates power grid positive sequence voltage markOne value；
Compare positive sequence voltage perunit value and electrical network high voltage threshold value, electrical network high voltage threshold value is according to concerned countries standard and isDesign objective of uniting determines, if being less than high voltage threshold, full power convertor and network reactive power from unit main control unit, and moreNew record gives watt current value at this time；If positive sequence voltage perunit value is higher than high voltage threshold, according to power grid positive sequence voltageGiven reactive current value is calculated, maximum given watt current calculated value is calculated further according to given reactive current value；
It the given watt current value of more new record and is currently calculated when being less than high voltage threshold according to power grid positive sequence voltageThe given watt current calculated value arrived takes small conduct therein currently to give watt current given value；
Grid-connected three-phase current given value is calculated according to given watt current value and given reactive current value；
Hysteretic loop current control unit is according to grid-connected three-phase current given value, Hysteresis control bandwidth and the grid-connected three-phase electricity of detectionStream calculation obtains the power switch control signal of control net side current transformer, and it is dynamic that corresponding power switch is controlled after drive amplificationMake；
Detection current transformer DC bus-bar voltage u in real timedc, as DC bus-bar voltage udcMore than the first mistake of DC bus-bar voltagePress threshold value udc_T1When control DC bus chopper circuit power switch it is open-minded, DC bus-bar voltage is more than the first overvoltage thresholdudc_T1More, power switch conducting dutycycle D is bigger, and chopping switch conducting dutycycle is with DC bus-bar voltage with the first over-pressed thresholdValue difference value is linear, when DC bus-bar voltage meets or exceeds the second overvoltage threshold of DC bus-bar voltage udc_T2When, powerSwitch is all open-minded；
After power switch is opened, DC bus will be released energy by letting out energy resistance.
Further, positive sequence voltage perunit value calculates as follows：
In formula, u*gIndicate power grid positive sequence voltage perunit value, ugPIndicate that isolated power grid positive sequence voltage hasValid value, ugrIndicate specified network voltage value.ugrIt is system fixed value, ugPIt is calculated by carrying out positive-negative sequence separation to network voltageIt obtains.
Further, the calculation formula for giving reactive current value and maximum given watt current calculated value distinguishes following instituteShow：
i*Q=2IN(u*g-u*gT)
In formula, i*QIt indicates to give reactive current value, u*gIndicate power grid positive sequence voltage perunit value, u*gTIndicate electricity
The high voltage threshold of net voltage；u*gTIt is determined according to concerned countries standard and system design objective.
In formula, iPmaxIndicate maximum given watt current calculated value, INIndicate the grid-connected rated current of current transformer, i*QTableShow given reactive current value, k1Indicate full power convertor overload capacity coefficient.INAnd k1It is determined according to current transformer design objective,Usual k1>1.
Further, the calculation formula for giving watt current value is as follows：
i*P=min (i*P_ref,iPmax)
I in formula*PIt indicates to give watt current value, i*P_refMore new record when power grid positive sequence voltage is less than high voltage thresholdGiven watt current value, iPmaxIndicate maximum given watt current calculated value.i*P_refIt is calculated by outer voltage；
Further, grid-connected three-phase current gives the following formula of value calculating method：
In above formula, ia_ref、ia_ref、ia_refRespectively grid-connected A, B, C phase current given value, i*PIt indicates to give watt currentValue, i*QIt indicates to give reactive current value, θ is the electric network voltage phase that network voltage phaselocked loop is calculated.θ is calculated by phaselocked loopIt obtains.
Further, duty ratio and the relationship of overvoltage threshold are expressed as：
K in formulacFor power switch Duty ratio control coefficient.：udcIt is the DC bus-bar voltage that sample detecting obtains, udc_T1And udc_T2According to power device pressure resistance andVoltage margin determines.
A kind of wind electric converter high voltage crossing device based on hysteretic loop current control, it is characterised in that：Including：Signal is examinedSurvey unit, system control unit, Hysteresis control unit and chop control unit, system control unit and chop control unit, letterNumber detection unit is connected with hysteretic loop current control unit by hardwire, for transmitting the control signal believed.Signal detection listMember is connect with chop control unit, hysteretic loop current control unit, system control unit by hardwire, the signal for that will acquireIt is transferred to each control unit.Chop control unit is connect with DC bus chopper circuit by hardwire.
The detecting signal unit for detecting power grid three-phase voltage, grid-connected three-phase current and DC bus-bar voltage in real time.
The power grid three-phase voltage that system control unit is obtained according to detection, isolates positive sequence voltage, determines that positive sequence voltage isIt is no to be more than electrical network high voltage threshold value, and be responsible for calculating the grid-connected three-phase current given value of power grid.
Hysteresis control unit is according to the calculated grid-connected three-phase current given value of system control unit and detecting signal unitThe grid-connected three-phase current of detection generates the PWM control letters of net side current transformer power switch in conjunction with preset stagnant loop bandwidthNumber.
Chop control unit judges whether to need enabled direct current female according to the DC bus-bar voltage that detecting signal unit detectsLine chopper circuit, and be responsible for generating the control signal of control copped wave electric wave circuit power switch.
Advantages of the present invention is：
The present invention by monitoring network voltage and judging whether to be higher than electrical network high voltage threshold value in real time, when network voltage is higher thanIt when electrical network high voltage threshold value, is calculated according to network voltage and gives reactive current given value, by absorbing a certain amount of nothing from power gridWork(inhibits network voltage to rise, advantageous to realize that off-grid is not run full power convertor when network voltage increases, and successfully realizes highVoltage failure passes through；
When network voltage is higher than electrical network high voltage threshold value, in the preferential premise for meeting and giving reactive current and giving outputUnder, the overload capacity of current transformer is made full use of, the maximum that current transformer can export is calculated and gives watt current calculated value, work as electricityThe given watt current value of more new record is more than maximum given watt current calculated value when net positive sequence voltage is less than high voltage thresholdWhen, current transformer gives watt current and is given by the given watt current calculated value of maximum, is advantageously implemented in this way to power grid and is presentedEnter most active power, is conducive to inhibit DC bus-bar voltage overvoltage；
D-c bus voltage value is monitored in the present invention in real time, control is straight when DC bus-bar voltage is more than DC bus threshold valueThe action of busbar chopper circuit is flowed, released energy current transformer off-grid fortune caused by DC bus-bar voltage can be inhibited to rise sharply by resistanceRow can further damage to avoid because of DC bus-bar voltage more than current transformer caused by operational envelope.
The present invention monitors power grid three-phase voltage and carries out positive-negative sequence separation to network voltage in real time, passes through positive sequence voltage componentTo judge whether network voltage high voltage occurs, it is possible to authenticate height electricity of the network voltage symmetrically and under asymmetric two kinds of different situationsFailure is pressed, and then controls current transformer and passes through high voltage fail.
Generator-side converter wear of the present invention uses hysteretic loop current control, hysteretic loop current control unit grid-connected according to calculating when controllingThe hysteresis current bandwidth of three-phase current given value and setting directly generates net side by the three-phase grid electric current with sampling backOther control parameters need not be arranged in current transformer power switch pwm signal, and control is simple, and dynamic response is fast.
Description of the drawings
Fig. 1 is the total power wind power generating set system control principle drawing of the embodiment of the present invention
Fig. 2 is the system composed structure schematic diagram of the embodiment of the present invention
Fig. 3 is that the total power wind-force generating converter electrical network high voltage of the embodiment of the present invention passes through control principle schematic diagram
Fig. 4 is that the total power wind-force generating converter of the embodiment of the present invention passes through the state of operation in network voltage overvoltageFigure
Specific implementation mode
Embodiment 1
Wind electric converter high voltage crossing control method based on Hysteresis control, it is characterised in that：
It is as follows：
The three-phase voltage for measuring power grid in real time carries out positive-negative sequence separation to network voltage, calculates power grid positive sequence voltage markOne value；
Compare positive sequence voltage perunit value and electrical network high voltage threshold value, electrical network high voltage threshold value is according to concerned countries standard and isDesign objective of uniting determines, if being less than high voltage threshold, full power convertor and network reactive power from unit main control unit, and moreNew record gives watt current value at this time；If positive sequence voltage perunit value is higher than high voltage threshold, according to power grid positive sequence voltageGiven reactive current value is calculated, maximum given watt current calculated value is calculated further according to given reactive current value；
It the given watt current value of more new record and is currently calculated when being less than high voltage threshold according to power grid positive sequence voltageThe given watt current calculated value arrived takes small conduct therein currently to give watt current given value；
Grid-connected three-phase current given value is calculated according to given watt current value and given reactive current value；
Hysteretic loop current control unit is according to grid-connected three-phase current given value, Hysteresis control bandwidth and the grid-connected three-phase electricity of detectionStream calculation obtains the power switch control signal of control net side current transformer, and it is dynamic that corresponding power switch is controlled after drive amplificationMake；
Detection current transformer DC bus-bar voltage u in real timedc, as DC bus-bar voltage udcMore than the first mistake of DC bus-bar voltagePress threshold value udc_T1When control DC bus chopper circuit power switch it is open-minded, DC bus-bar voltage is more than the first overvoltage thresholdudc_T1More, power switch conducting dutycycle D is bigger, and chopping switch conducting dutycycle is with DC bus-bar voltage with the first over-pressed thresholdValue difference value is linear, when DC bus-bar voltage meets or exceeds the second overvoltage threshold of DC bus-bar voltage udc_T2When, powerSwitch is all open-minded；
After power switch is opened, DC bus will be released energy by letting out energy resistance.
Embodiment 2
Wind electric converter high voltage crossing control method based on Hysteresis control, it is characterised in that：
It is as follows：
The three-phase voltage for measuring power grid in real time carries out positive-negative sequence separation to network voltage, calculates power grid positive sequence voltage markOne value；
Compare positive sequence voltage perunit value and electrical network high voltage threshold value, electrical network high voltage threshold value is according to concerned countries standard and isDesign objective of uniting determines, if being less than high voltage threshold, full power convertor and network reactive power from unit main control unit, and moreNew record gives watt current value at this time；If positive sequence voltage perunit value is higher than high voltage threshold, according to power grid positive sequence voltageGiven reactive current value is calculated, maximum given watt current calculated value is calculated further according to given reactive current value；
It the given watt current value of more new record and is currently calculated when being less than high voltage threshold according to power grid positive sequence voltageThe given watt current calculated value arrived takes small conduct therein currently to give watt current given value；
Grid-connected three-phase current given value is calculated according to given watt current value and given reactive current value；
Hysteretic loop current control unit is according to grid-connected three-phase current given value, Hysteresis control bandwidth and the grid-connected three-phase electricity of detectionStream calculation obtains the power switch control signal of control net side current transformer, and it is dynamic that corresponding power switch is controlled after drive amplificationMake；
Detection current transformer DC bus-bar voltage u in real timedc, as DC bus-bar voltage udcMore than the first mistake of DC bus-bar voltagePress threshold value udc_T1When control DC bus chopper circuit power switch it is open-minded, DC bus-bar voltage is more than the first overvoltage thresholdudc_T1More, power switch conducting dutycycle D is bigger, and chopping switch conducting dutycycle is with DC bus-bar voltage with the first over-pressed thresholdValue difference value is linear, when DC bus-bar voltage meets or exceeds the second overvoltage threshold of DC bus-bar voltage udc_T2When, powerSwitch is all open-minded；
After power switch is opened, DC bus will be released energy by letting out energy resistance.
Further, positive sequence voltage perunit value calculates as follows：
In formula, u*gIndicate power grid positive sequence voltage perunit value, ugPIndicate that isolated power grid positive sequence voltage hasValid value, ugrIndicate specified network voltage value.ugrIt is system fixed value, ugPIt is calculated by carrying out positive-negative sequence separation to network voltageIt obtains.
Further, the calculation formula for giving reactive current value and maximum given watt current calculated value distinguishes following instituteShow：
i*Q=2IN(u*g-u*gT)
In formula, i*QIt indicates to give reactive current value, u*gIndicate power grid positive sequence voltage perunit value, u*gTIndicate electricity
The high voltage threshold of net voltage；u*gTIt is determined according to concerned countries standard and system design objective.
In formula, iPmaxIndicate maximum given watt current calculated value, INIndicate the grid-connected rated current of current transformer, i*QTableShow given reactive current value, k1Indicate full power convertor overload capacity coefficient.INAnd k1It is determined according to current transformer design objective,Usual k1>1.
Further, the calculation formula for giving watt current value is as follows：
i*P=min (i*P_ref,iPmax)
I in formula*PIt indicates to give watt current value, i*P_refMore new record when power grid positive sequence voltage is less than high voltage thresholdGiven watt current value, iPmaxIndicate maximum given watt current calculated value.i*P_refIt is calculated by outer voltage；
Further, grid-connected three-phase current gives the following formula of value calculating method：
In above formula, ia_ref、ia_ref、ia_refRespectively grid-connected A, B, C phase current given value, i*PIt indicates to give watt currentValue, i*QIt indicates to give reactive current value, θ is the electric network voltage phase that network voltage phaselocked loop is calculated.θ is calculated by phaselocked loopIt obtains.
Further, duty ratio and the relationship of overvoltage threshold are expressed as：
K in formulacFor power switch Duty ratio control coefficient.：udcIt is the DC bus-bar voltage that sample detecting obtains, udc_T1And udc_T2According to power device pressure resistance andVoltage margin determines.
Embodiment 3
A kind of wind electric converter high voltage crossing device based on hysteretic loop current control, it is characterised in that：Including：Signal is examinedSurvey unit, system control unit, Hysteresis control unit and chop control unit, system control unit and chop control unit, letterNumber detection unit is connected with hysteretic loop current control unit by hardwire, for transmitting the control signal believed.Signal detection listMember is connect with chop control unit, hysteretic loop current control unit, system control unit by hardwire, the signal for that will acquireIt is transferred to each control unit.Chop control unit is connect with DC bus chopper circuit by hardwire,.
Embodiment 4
A kind of wind electric converter high voltage crossing device based on hysteretic loop current control includes：Detecting signal unit, systemControl unit, Hysteresis control unit and chop control unit, system control unit and chop control unit, detecting signal unit andHysteretic loop current control unit is connected by hardwire, for transmitting the control signal believed.Detecting signal unit and chop controlUnit, hysteretic loop current control unit, system control unit are connected by hardwire, and the signal transmission for that will acquire gives each controlUnit processed.Chop control unit is connect with DC bus chopper circuit by hardwire.
The detecting signal unit for detecting power grid three-phase voltage, grid-connected three-phase current and DC bus-bar voltage in real time.
The power grid three-phase voltage that system control unit is obtained according to detection, isolates positive sequence voltage, determines that positive sequence voltage isIt is no to be more than electrical network high voltage threshold value, and be responsible for calculating the grid-connected three-phase current given value of power grid.
Hysteresis control unit is according to the calculated grid-connected three-phase current given value of system control unit and detecting signal unitThe grid-connected three-phase current of detection generates the PWM control letters of net side current transformer power switch in conjunction with preset stagnant loop bandwidthNumber.
Chop control unit judges whether to need enabled direct current female according to the DC bus-bar voltage that detecting signal unit detectsLine chopper circuit, and be responsible for generating the control signal of control copped wave electric wave circuit power switch.
Embodiment 5
Wind electric converter high voltage crossing control method based on Hysteresis control, is as follows：
The three-phase voltage for measuring power grid in real time carries out positive-negative sequence separation to network voltage, calculates power grid positive sequence voltage markOne value；
Compare positive sequence voltage perunit value and electrical network high voltage threshold value, electrical network high voltage threshold value is according to concerned countries standard and isDesign objective of uniting determines, if being less than high voltage threshold, full power convertor and network reactive power from unit main control unit, and moreNew record gives watt current value at this time；If positive sequence voltage perunit value is higher than high voltage threshold, according to power grid positive sequence voltageGiven reactive current value is calculated, maximum given watt current calculated value is calculated further according to given reactive current value；
It the given watt current value of more new record and is currently calculated when being less than high voltage threshold according to power grid positive sequence voltageThe given watt current calculated value arrived takes small conduct therein currently to give watt current given value；
Grid-connected three-phase current given value is calculated according to given watt current value and given reactive current value；
Hysteretic loop current control unit is according to grid-connected three-phase current given value, Hysteresis control bandwidth and the grid-connected three-phase electricity of detectionStream calculation obtains the power switch control signal of control net side current transformer, and it is dynamic that corresponding power switch is controlled after drive amplificationMake；
Detection current transformer DC bus-bar voltage u in real timedc, as DC bus-bar voltage udcMore than the first mistake of DC bus-bar voltagePress threshold value udc_T1When control DC bus chopper circuit power switch it is open-minded, DC bus-bar voltage is more than the first overvoltage thresholdudc_T1More, power switch conducting dutycycle D is bigger, and chopping switch conducting dutycycle is with DC bus-bar voltage with the first over-pressed thresholdValue difference value is linear, when DC bus-bar voltage meets or exceeds the second overvoltage threshold of DC bus-bar voltage udc_T2When, powerSwitch is all open-minded；
After power switch is opened, DC bus will be released energy by letting out energy resistance.
Further, positive sequence voltage perunit value calculates as follows：
In formula, u*gIndicate power grid positive sequence voltage perunit value, ugPIndicate that isolated power grid positive sequence voltage hasValid value, ugrIndicate specified network voltage value.ugrIt is system fixed value, ugPIt is calculated by carrying out positive-negative sequence separation to network voltageIt obtains.
Further, the calculation formula for giving reactive current value and maximum given watt current calculated value distinguishes following instituteShow：
i*Q=2IN(u*g-u*gT)
In formula, i*QIt indicates to give reactive current value, u*gIndicate power grid positive sequence voltage perunit value, u*gTIndicate electricity
The high voltage threshold of net voltage；u*gTIt is determined according to concerned countries standard and system design objective.
In formula, iPmaxIndicate maximum given watt current calculated value, INIndicate the grid-connected rated current of current transformer, i*QTableShow given reactive current value, k1Indicate full power convertor overload capacity coefficient.INAnd k1It is determined according to current transformer design objective,Usual k1>1.
Further, the calculation formula for giving watt current value is as follows：
i*P=min (i*P_ref,iPmax)
I in formula*PIt indicates to give watt current value, i*P_refMore new record when power grid positive sequence voltage is less than high voltage thresholdGiven watt current value, iPmaxIndicate maximum given watt current calculated value.i*P_refIt is calculated by outer voltage；
Further, grid-connected three-phase current gives the following formula of value calculating method：
In above formula, ia_ref、ia_ref、ia_refRespectively grid-connected A, B, C phase current given value, i*PIt indicates to give watt currentValue, i*QIt indicates to give reactive current value, θ is the electric network voltage phase that network voltage phaselocked loop is calculated.θ is calculated by phaselocked loopIt obtains.
Further, duty ratio and the relationship of overvoltage threshold are expressed as：
K in formulacFor power switch Duty ratio control coefficient.：udcIt is the DC bus-bar voltage that sample detecting obtains, udc_T1And udc_T2According to power device pressure resistance andVoltage margin determines.
A kind of wind electric converter high voltage crossing device based on hysteretic loop current control, it is characterised in that：Including：Signal is examinedSurvey unit, system control unit, Hysteresis control unit and chop control unit, system control unit and chop control unit, letterNumber detection unit is connected with hysteretic loop current control unit by hardwire, for transmitting the control signal believed.Signal detection listMember is connect with chop control unit, hysteretic loop current control unit, system control unit by hardwire, the signal for that will acquireIt is transferred to each control unit.Chop control unit is connect with DC bus chopper circuit by hardwire.
The detecting signal unit for detecting power grid three-phase voltage, grid-connected three-phase current and DC bus-bar voltage in real time.
The power grid three-phase voltage that system control unit is obtained according to detection, isolates positive sequence voltage, determines that positive sequence voltage isIt is no to be more than electrical network high voltage threshold value, and be responsible for calculating the grid-connected three-phase current given value of power grid.
Hysteresis control unit is according to the calculated grid-connected three-phase current given value of system control unit and detecting signal unitThe grid-connected three-phase current of detection generates the PWM control letters of net side current transformer power switch in conjunction with preset stagnant loop bandwidthNumber.
Chop control unit judges whether to need enabled direct current female according to the DC bus-bar voltage that detecting signal unit detectsLine chopper circuit, and be responsible for generating the control signal of control copped wave electric wave circuit power switch.
The present invention by monitoring network voltage and judging whether to be higher than electrical network high voltage threshold value in real time, when network voltage is higher thanIt when electrical network high voltage threshold value, is calculated according to network voltage and gives reactive current given value, by absorbing a certain amount of nothing from power gridWork(inhibits network voltage to rise, advantageous to realize that off-grid is not run full power convertor when network voltage increases, and successfully realizes highVoltage failure passes through；
When network voltage is higher than electrical network high voltage threshold value, in the preferential premise for meeting and giving reactive current and giving outputUnder, the overload capacity of current transformer is made full use of, the maximum that current transformer can export is calculated and gives watt current calculated value, work as electricityThe given watt current value of more new record is more than maximum given watt current calculated value when net positive sequence voltage is less than high voltage thresholdWhen, current transformer gives watt current and is given by the given watt current calculated value of maximum, is advantageously implemented in this way to power grid and is presentedEnter most active power, is conducive to inhibit DC bus-bar voltage overvoltage；
D-c bus voltage value is monitored in the present invention in real time, control is straight when DC bus-bar voltage is more than DC bus threshold valueThe action of busbar chopper circuit is flowed, released energy current transformer off-grid fortune caused by DC bus-bar voltage can be inhibited to rise sharply by resistanceRow can further damage to avoid because of DC bus-bar voltage more than current transformer caused by operational envelope.
The present invention monitors power grid three-phase voltage and carries out positive-negative sequence separation to network voltage in real time, passes through positive sequence voltage componentTo judge whether network voltage high voltage occurs, it is possible to authenticate height electricity of the network voltage symmetrically and under asymmetric two kinds of different situationsFailure is pressed, and then controls current transformer and passes through high voltage fail.
Generator-side converter wear of the present invention uses hysteretic loop current control, hysteretic loop current control unit grid-connected according to calculating when controllingThe hysteresis current bandwidth of three-phase current given value and setting directly generates net side by the three-phase grid electric current with sampling backOther control parameters need not be arranged in current transformer power switch pwm signal, and control is simple, and dynamic response is fast.
A kind of high voltage crossing control method and device based on hysteretic loop current control are provided in the present embodiment.Such as Fig. 1Shown is total power wind power generating set system control principle drawing.Wind turbine is by absorbing wind energy rotation forces wind turbine power generationGenerator is sent out the convert alternating current of voltage to frequency variation into DC voltage by operation, generator-side converter wear, and net side current transformer is responsible forBy DC power conversion at alternating current feed-in power grid.When overvoltage occurs for network voltage, corresponding control unit controls net side unsteady flowDevice and chopper circuit carry out high voltage crossing control to overvoltage failure.
Fig. 2 is the high voltage crossing control device composed structure schematic diagram of total power wind-force generating converter in embodiment,Total power wind-force generating converter ontology is by generator-side converter wear, DC bus copped wave unit, DC bus and net side current transformer structureAt.Current transformer high voltage crossing control device includes detecting signal unit, system control unit, chop control unit and stagnant ring electricityFlow control unit.Detecting signal unit detects network voltage, DC bus-bar voltage and net side current transformer grid-connected current, system controlUnit carries out positive-negative sequence separation according to the obtained network voltage of detection, calculate power grid positive sequence voltage perunit value and with the high electricity of power gridPressure threshold value is compared, and when power grid positive sequence voltage perunit value is higher than electrical network high voltage threshold value, on the one hand enables chop control listMember, the DC bus-bar voltage driving DC bus chopper circuit action that copped wave unit is obtained further according to detection；On the other hand, systemControl unit is calculated that net side current transformer is active and reactive command according to power grid positive sequence voltage perunit value, and according to control unitThe grid phase that internal phaselocked loop is calculated calculates the current-order of net side hysteretic loop current control unit, hysteretic loop current control listMember generates the pwm control signal of control net side current transformer according to the grid-connected current that current-order and detection obtain.
Be shown in Fig. 3 the embodiment of the present invention total power wind-force generating converter electrical network high voltage pass through control principle signalFigure, when power grid positive sequence voltage perunit value is less than electrical network high voltage threshold value, height wears enabled switch and pushes position 1, and watt current is givenDefinite value ip*It is calculated by DC bus-bar voltage outer shroud, i.e. iP*=iP_ref；Reactive current given value is given from master control, i.e. iq*=iq_ref。
When power grid positive sequence voltage perunit value is higher than electrical network high voltage threshold value, height wears enabled switch and pushes position 2, according to electricityNet positive sequence voltage perunit value ug*, electrical network high voltage threshold value ugT*With current transformer rated current INCalculate given reactive current value i*Q=2IN(u*g-u*gT), further according to the overload capacity coefficient k of current transformer1, it is calculated maximum active to constant currentThe given watt current value of more new record when it and power grid positive sequence voltage are less than high voltage thresholdiP_refIt is compared, selects small as watt current given value, i.e. iP*=min (iP_ref,iPmax).Instruction current generates singleMember instructs i according to watt currentP*, referenced reactive current iQ*And the grid phase θ that phaselocked loop is calculated, it is calculated stagnantThree-phase current needed for ring control instructs ia_ref、ib_refAnd ic_ref.Final Hysteresis control unit is instructed and is examined according to three-phase currentThe grid-connected three-phase current surveyed obtains the power switch control signal of net side current transformer.
When power grid positive sequence voltage perunit value is higher than electrical network high voltage threshold value, DC bus-bar voltage may be because that power grid is excessively electricPressure and it is over-pressed, at this moment DC bus chop control unit is over-pressed according to the DC bus-bar voltage and DC bus-bar voltage that detect in real timeThreshold value controls chopper circuit power switch, and direct current is controlled when DC bus-bar voltage is more than the first overvoltage threshold of DC bus-bar voltageBusbar chopper circuit power switch is open-minded, and DC bus-bar voltage is more than that the first overvoltage threshold is more, power switch conducting dutycycleBigger, chopping switch conducting dutycycle is linear with the first overvoltage threshold difference with DC bus-bar voltage, works as DC busWhen voltage meets or exceeds the second overvoltage threshold of DC bus-bar voltage, power switch is all open-minded.After power switch is opened, direct currentBusbar will be released energy by letting out energy resistance.
Fig. 4 is that the total power wind-force generating converter of the embodiment of the present invention passes through the state of operation in network voltage overvoltageScheme, corresponding waveform is followed successively by power grid A phase voltages (V), power grid A phase voltages perunit value (pu), DC bus from top to bottom in figureVoltage (V), current transformer grid-connected current (A) and the capacitive reactive power (Var) for injecting power grid.As can be seen that working as power grid positive sequence voltage markWhen one value reaches 1.3pu, electrical network high voltage threshold value (being set as 1.1pu in embodiment) is reached, at this moment net side current transformer height is wornEnabled switch pushes position 2, high voltage crossing control method of the invention effect, the capacitive that control current transformer is born to power grid injectionIt is idle, while talkaround, current transformer DC bus-bar voltage are not less than 1300V, are limited in safe range current transformer.Power gridAfter voltage restores normal, current transformer height wears enabled switch and pushes position 1 from newly, and logic when current transformer is by normal power grid is controlledSystem.Unit overvoltage passes through operating status figure and illustrates the high voltage crossing controlling party proposed by the present invention based on hysteretic loop current controlMethod can control total power wind-force generating converter and successfully pass through high voltage fail, ensure the safe and stable operation of current transformer.