CN104617584B - A kind of fault ride-through of power grid method and apparatus of total power wind power system - Google Patents
A kind of fault ride-through of power grid method and apparatus of total power wind power system Download PDFInfo
- Publication number
- CN104617584B CN104617584B CN201510080562.6A CN201510080562A CN104617584B CN 104617584 B CN104617584 B CN 104617584B CN 201510080562 A CN201510080562 A CN 201510080562A CN 104617584 B CN104617584 B CN 104617584B
- Authority
- CN
- China
- Prior art keywords
- grid
- voltage
- power
- side converter
- fault
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000003745 diagnosis Methods 0.000 claims abstract description 19
- 239000013598 vector Substances 0.000 claims description 33
- 230000001939 inductive effect Effects 0.000 claims description 21
- 230000000903 blocking effect Effects 0.000 claims description 9
- 238000005516 engineering process Methods 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 5
- 230000000630 rising effect Effects 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 3
- 238000001514 detection method Methods 0.000 abstract description 4
- 230000006641 stabilisation Effects 0.000 abstract 3
- 238000011105 stabilization Methods 0.000 abstract 3
- 230000000452 restraining effect Effects 0.000 description 10
- 238000011217 control strategy Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 230000001965 increasing effect Effects 0.000 description 7
- 230000002401 inhibitory effect Effects 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
-
- H02J3/386—
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Landscapes
- Control Of Eletrric Generators (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
This application discloses a kind of fault ride-through of power grid method and apparatus of total power wind power system, this method includes：Fault diagnosis is carried out to line voltage；After line voltage generation three-phase equilibrium is fallen, whether detection line voltage falls stabilization in a low voltage state；When line voltage falls stabilization in a low voltage state, capacitive reactive power compensation control is carried out to net side current transformer according to the amplitude of falling of line voltage；After line voltage generation three-phase equilibrium rises sharply, whether detection line voltage rises sharply stably in a high voltage state；When line voltage rises sharply stabilization in a high voltage state, judge whether net side current transformer is in modulation condition；If net side current transformer is in modulation condition, lagging reactive power compensation is carried out to net side current transformer according to the amplitude that rises sharply of line voltage to control, otherwise pressure block is carried out to the driving signal of power switching tube of net side current transformer, so that total power wind power system can smoothly tide over grid voltage three-phase balance and fall or the region that rises sharply.
Description
Technical Field
The invention relates to the technical field of grid fault ride-through, in particular to a grid fault ride-through method and device of a full-power wind power system.
Background
The full-power wind power system comprises a wind generating set 10, a machine side converter 20, a crowbar circuit 30, a direct-current support capacitor C, a grid side converter 40, a filter circuit 50 and the like, and the structural schematic diagram of the full-power wind power system is shown in FIG. 1.
In a full-power wind power system, a three-phase balance drop or sudden rise of the grid voltage is a common fault: the grid voltage three-phase balance drop can cause the output power of a grid-side converter to be reduced, the energy of the grid side and the energy of a machine side are not matched, the grid voltage three-phase balance sudden rise can cause the energy of the grid-side converter to reversely flow, and under the two conditions, the direct-current supporting voltage udcThe current transformer can rapidly rise, so that impact is caused to bridge arm side power switching tubes of a direct current support capacitor and a grid side converter, and the service lives and the use reliability of the capacitor and the power switching tubes are seriously threatened; in addition, the three-phase balance sudden rise of the grid voltage can also cause the grid-side converter to enter an overmodulation state, and the stable operation of the grid-side converter is seriously damaged.
Therefore, how to enable the full-power wind power system to smoothly bridge the three-phase balance drop or sudden rise area of the power grid voltage becomes a problem which needs to be solved for realizing the stable and safe operation of the full-power wind power system.
Disclosure of Invention
In view of this, the invention provides a grid fault ride-through method and device for a full-power wind power system, so that the full-power wind power system can smoothly bridge a grid voltage three-phase balance drop or swell region.
A grid fault ride-through method of a full-power wind power system comprises the following steps:
carrying out fault diagnosis on the power grid voltage of the full-power wind power system;
after the three-phase balance drop fault of the power grid voltage is diagnosed, detecting whether the power grid voltage drops stably in a low-voltage state in real time; when the grid voltage is detected to drop stably in a low-voltage state, capacitive reactive power compensation control is carried out on the grid-side converter according to the dropping amplitude of the grid voltage;
after the three-phase balance sudden rising fault of the power grid voltage is diagnosed, detecting whether the power grid voltage suddenly rises stably in a high-voltage state in real time; when the sudden rise and stability of the voltage of the power grid under a high-voltage state are detected, judging whether the grid-side converter is in a modulation state or not; if the grid-side converter is in a modulation state, performing inductive reactive power compensation control on the grid-side converter according to the sudden rise amplitude of the grid voltage; and if the grid-side converter is in an overmodulation state, forcibly blocking a power switch tube driving signal of the grid-side converter.
The fault diagnosis of the grid voltage of the full-power wind power system comprises the following steps:
calculating to obtain the amplitude of the positive sequence voltage of the power grid by adopting a double-synchronous coordinate system decoupling software phase-locked loop technology;
when the amplitude of the positive sequence voltage of the power grid is lower than the lower limit of the normal amplitude, judging that the three-phase balance drop fault occurs to the power grid voltage; and when the amplitude of the positive sequence voltage of the power grid is higher than the upper limit of the normal amplitude, judging that the three-phase balance sudden-rise fault occurs to the power grid voltage.
Optionally, before performing fault diagnosis on the grid voltage of the full-power wind power system, the method further includes: and modulating the machine side converter and the grid side converter in the full-power wind power system by adopting a space vector pulse width modulation mode.
Optionally, after the grid-side converter is judged to be in the modulation state, the method further includes: and performing direct-current voltage conversion control on the grid-side converter.
Optionally, after the three-phase balance drop fault of the grid voltage is diagnosed, and after the three-phase balance swell fault of the grid voltage is diagnosed, the method further includes: and carrying out power-limiting operation control on the machine side converter.
Optionally, after the three-phase balance drop fault of the grid voltage is diagnosed, and after the three-phase balance swell fault of the grid voltage is diagnosed, the method further includes:
judging whether the bridge arm side current of the grid side converter is within a safety threshold range;
and when the bridge arm side current of the grid-side converter exceeds the safety threshold range, forcibly blocking the power switch tube driving signal of the grid-side converter.
A grid fault ride-through device of a full power wind power system, comprising:
the fault diagnosis unit is used for carrying out fault diagnosis on the power grid voltage of the full-power wind power system;
the low-voltage ride-through unit is used for detecting whether the power grid voltage falls stably in a low-voltage state in real time after the power grid voltage is diagnosed to have a three-phase balance falling fault; when the grid voltage is detected to drop stably in a low-voltage state, capacitive reactive power compensation control is carried out on the grid-side converter according to the dropping amplitude of the grid voltage;
the high voltage ride through unit is used for detecting whether the power grid voltage suddenly rises stably in a high voltage state in real time after the power grid voltage is diagnosed to have a three-phase balance sudden rise fault; when the sudden rise and stability of the voltage of the power grid under a high-voltage state are detected, judging whether the grid-side converter is in a modulation state or not; if the grid-side converter is in a modulation state, performing inductive reactive power compensation control on the grid-side converter according to the sudden rise amplitude of the grid voltage; and if the grid-side converter is in an overmodulation state, forcibly blocking a power switch tube driving signal of the grid-side converter.
Wherein the fault diagnosis unit includes:
the amplitude acquisition unit is used for calculating the amplitude of the positive sequence voltage of the power grid by adopting a double-synchronous coordinate system decoupling software phase-locked loop technology;
the fault determination unit is used for determining that the three-phase balance drop fault occurs to the power grid voltage when the amplitude of the power grid positive sequence voltage is lower than the lower limit of the normal amplitude; and when the amplitude of the positive sequence voltage of the power grid is higher than the upper limit of the normal amplitude, judging that the three-phase balance sudden-rise fault occurs to the power grid voltage.
Optionally, the apparatus further comprises: and the modulation unit is used for modulating the machine side converter and the grid side converter in the full-power wind power system by adopting a space vector pulse width modulation mode before fault diagnosis is carried out on the grid voltage of the full-power wind power system.
Optionally, the high voltage ride through unit is further configured to perform dc voltage conversion control on the grid-side converter after the grid-side converter is determined to be in the modulation state.
According to the technical scheme, in order to ensure that the full-power wind power system smoothly crosses a three-phase balance drop or swell area of the power grid voltage, the capacitive reactive power compensation control is carried out on the grid-side converter by judging and identifying different fault types of the power grid voltage and adopting a corresponding control strategy when the three-phase balance drop and drop stability of the power grid voltage occur, so that a certain restraining effect on the power grid drop is achieved, and the LVRT is realized; when three-phase balance sudden rise and sudden rise stability occur to the voltage of the power grid, inductive reactive power compensation control is carried out on the grid-side converter, so that a certain restraining effect is achieved on the sudden rise of the power grid, HVRT is achieved, meanwhile, the inductive reactive power compensation control can restrain the modulation degree from tending to saturation through restraining the sudden rise of the power grid, the grid-side converter can stably run in a modulation area, and the problems in the prior art are solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a full power wind power system disclosed in the prior art;
FIG. 2 is a flowchart of a grid fault ride-through method for a full-power wind power system according to an embodiment of the present invention;
FIG. 3 is a graph of a space voltage vector distribution disclosed in the prior art;
fig. 4a is a vector diagram of ac sides of a grid-side converter under a sudden rise of a grid voltage according to an embodiment of the present invention;
fig. 4b is a vector diagram of an ac side during inductive reactive power compensation control of a grid-side converter under a stable sudden voltage rise of a power grid according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a grid fault ride-through device of a full-power wind power system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 2, the embodiment of the invention discloses a grid fault ride-through method for a full-power wind power system, so that the full-power wind power system can smoothly bridge a three-phase balanced drop or swell area of a grid voltage, comprising the following steps:
step 201: performing fault diagnosis on the power grid voltage of the full-power wind power system, and entering step 202 after the three-phase balance drop fault of the power grid voltage is diagnosed; after the three-phase balance sudden-rise fault of the power grid voltage is diagnosed, the step 204 is carried out;
step 202: detecting whether the grid voltage falls stably in a low-voltage state in real time, and entering step 203 when the grid voltage falls stably in the low-voltage state is detected;
step 203: and performing capacitive reactive power compensation control on the grid-side converter according to the voltage drop amplitude of the power grid, so as to realize low-voltage fault ride-through of the full-power wind power system.
Step 204: detecting whether the grid voltage suddenly rises and is stable in a high-voltage state in real time, and entering step 205 when the grid voltage suddenly rises and is stable in the high-voltage state;
step 205: judging whether the grid-side converter is in a modulation state, if so, entering a step 206; if the grid-side converter is in the over-modulation state, the step 207 is entered;
step 206: and performing inductive reactive power compensation control on the grid-side converter according to the sudden rise amplitude of the grid voltage to realize high-voltage fault ride-through of the full-power wind power system.
Step 207: and the driving signal of a power switch tube of the grid-side converter is forcibly blocked, so that the grid-side converter is prevented from seriously harming the stable operation of the grid-side converter due to uncontrollable alternating-current side voltage.
When the full-power wind power system is normally operated in a grid-connected mode, the machine side converter adopts a double-loop control strategy of a wind power generation power outer loop and a motor stator current inner loop, so that on the premise of carrying out real-time tracking control on given wind power generation power, the vector control without a speed sensor and the optimal control of stator current are realized.
The grid-side converter adopts a double-loop control strategy of a direct-current voltage outer loop and a power grid current inner loop. The DC voltage outer ring gives a DC supporting voltage given valueWith the actual DC support voltage udcThe deviation between the positive sequence current and the negative sequence current is input into an outer ring regulator, and in order to keep the DC supporting voltage constant, the output of the outer ring regulator is the given value of the positive sequence current active component of the power gridIn the case of a unity power factor network, the given value of the positive sequence current reactive component of the networkTypically set to zero. The power grid current inner ring realizes the reactive and active components of the power grid positive sequence current through a positive sequence and negative sequence double-current inner ring structure with completely symmetrical structureReactive and active components of the grid negative sequence currentIn actual occasions, in order to ensure normal on-grid operation of a grid-side converter and three-phase symmetrical control of bridge-arm-side grid current, the reactive and active components of the negative-sequence current of the grid are respectively controlledIs 0.
When the grid voltage of the full-power wind power system has a three-phase balanced drop or swell fault, in order to ensure the stability and safety and reliability of the system, the system is required to smoothly transit a three-phase balanced drop or swell region of the grid voltage, so as to realize the uninterrupted grid-connected operation of the system under the condition of the grid fault, that is, the full-power wind power system is required to have an FRT (fault-ride-through) capability, wherein the FRT capability of the full-power wind power system under the grid voltage three-phase balanced drop fault is called an LVRT (Low voltage ride-through) capability, and the FRT capability of the full-power wind power system under the grid voltage three-phase balanced swell fault is called an HVRT (High voltage ride-through) capability.
In order to ensure that a full-power wind power system smoothly crosses a three-phase balance drop or sudden rise area of the power grid voltage, the embodiment adopts a corresponding control strategy by judging and identifying different fault types of the power grid voltage, and performs capacitive reactive power compensation control on a grid-side converter when the three-phase balance drop and drop stability of the power grid voltage occur, so that a certain restraining effect on the power grid drop is achieved, and the system has LVRT capability; when three-phase balance sudden rise and sudden rise stability occur to the voltage of the power grid, inductive reactive power compensation control is carried out on the grid-side converter, so that a certain inhibiting effect is achieved on the sudden rise of the power grid, the system has HVRT capability, the effect of inhibiting the sudden rise of the power grid and the condition that the modulation degree tends to be saturated can be achieved, the grid-side converter can stably operate in a modulation area, and the problems in the prior art are solved. Next, steps 201 to 207 disclosed in the present embodiment will be described.
1) Step 201
The method for identifying the fault type of the grid voltage of the full-power wind power system mainly comprises the following steps: calculating to obtain the amplitude of the positive sequence voltage of the power grid by adopting a double synchronous coordinate system decoupling software phase-locked loop (DDSRF-SPLL) technology; when the amplitude of the positive sequence voltage of the power grid is lower than the lower limit of the normal amplitude, judging that the three-phase balance drop fault occurs to the power grid voltage; and when the amplitude of the positive sequence voltage of the power grid is higher than the upper limit of the normal amplitude, judging that the three-phase balance sudden-rise fault occurs to the power grid voltage.
The grid-side converter can perform grid-connected current loop control of grid positive sequence voltage orientation according to a grid voltage positive sequence angle of the DDSRF-SPLL phase lock, and feeds active power to a grid by set maximum positive sequence current. Usually, the normal amplitude range is defined as the nominal grid positive sequence voltage amplitude of ± 10% in the field, and then, when the normal amplitude range is defined as the nominal grid positive sequence voltage amplitudeWhen the three-phase balance of the grid voltage drops, the system can judge that the three-phase balance of the grid voltage dropsThen, the three-phase balance sudden rise of the grid voltage can be judged, wherein upIs the amplitude of the positive sequence voltage of the power grid,is the amplitude of the positive sequence voltage reactive component of the power grid,the amplitude of the positive sequence voltage active component of the power grid is obtained.Andall are obtained by direct calculation through DDSRF-SPLL technology.
Compared with other power grid positive sequence voltage amplitude detection technologies, the DDSRF-SPLL can realize the rapid and vibration-free extraction of the positive and negative sequence voltage components of the power grid, so that the real-time performance and the accuracy of the power grid voltage three-phase balance drop or swell fault detection are ensured.
2) Step 202 and step 204
In step 201, the identification of different fault types of the grid voltage belongs to a transient process, and control strategies correspondingly adopted for different fault types need to be performed in a steady-state process, so that steady-state judgment needs to be performed after the fault types are identified. The method specifically comprises the following steps: under the condition that the three-phase balance drop fault of the power grid voltage is judged, detecting the fluctuation quantity of the positive sequence voltage amplitude of the power grid in real time, and judging that the power grid voltage drops stably in a low-voltage state when the fluctuation quantity is in a preset fluctuation range; and under the condition that the three-phase balance sudden rising fault of the power grid voltage is judged, the fluctuation amount of the positive sequence voltage amplitude of the power grid is also detected in real time, and when the fluctuation amount is in a preset fluctuation range, the sudden rising stability of the power grid voltage in a high-voltage state is judged.
3) Step 203, step 205 to step 207
For the condition that the grid voltage is stable in sudden rise under a high voltage state, in this embodiment, when the grid-side converter is in a modulation state, the inductive reactive power compensation control is performed on the grid-side converter according to the sudden rise amplitude of the grid voltage, that is, the inductive reactive power is compensated according to the sudden rise amplitude of the grid, so that a certain blocking effect is performed on the sudden rise of the grid voltage, the grid recovery is supported, and the system has HVRT capability. Meanwhile, the inductive reactive power compensation control can also inhibit the saturation of the modulation degree by inhibiting the rise of the alternating-current side voltage of the grid-side converter, so that the alternating-current side voltage of the grid-side converter is controlled in a modulation range.
In addition, when the sudden rise amplitude of the power grid is large, the direct-current voltage of the grid-side converter can be controlled at the same time. The variable direct-current voltage control is to raise the direct-current voltage to improve the controllable range of the alternating-current side voltage of the grid-side converter, so that the aim of restraining the modulation degree from approaching saturation is fulfilled.
In this embodiment, the grid-side converter and the machine-side converter preferably adopt an SVPWM (Space Vector Pulse width modulation) mode. Compared with a traditional Sinusoidal Pulse Width Modulation (SPWM) mode, the SVPWM has the advantages of high utilization rate of direct-current bus voltage, large modulation degree for realizing linear modulation and the like, and the controllable range of the converter is enlarged.
Next, the inductive reactive power compensation control and the dc-to-dc voltage control will be described by taking SVPWM modulation as an example.
Defining the modulation degree of SVPWM as m, then
In the formula, | V*Is the magnitude of a given space voltage vector,is the fundamental amplitude, V, of the output phase voltage of the converter operating in square wave modedcIs the dc input voltage of the converter.
The known principle of the converter adopting SVPWM modulation is as follows: expressing the AC side voltage of the converter by a rotating space voltage vector V, wherein the instantaneous value of V is the instantaneous value of the output voltage of the converter; the rotation space of V can be divided into a plurality of sectors, as shown in fig. 3, V rotated into any sector can be synthesized by three adjacent fixed basic space voltage vectors located at the boundary of the small sector, so that the mode length and direction of V are also controlled by controlling the acting time of the three basic space voltage vectors participating in vector synthesis. Under SVPWM modulation, there are 19 such basic space voltage vectors, 1 zero vector V respectively06 amplitude values ofShort vector V of1～V66 amplitude values ofMiddle vector V of7～V12And 6 amplitudes areLong vector V of13～V18。
As can be seen from the space voltage vector distribution diagram shown in fig. 3, when vector synthesis is performed, any one of the space voltage vectors V that can be output by the grid-side converter is always positioned at V13～V18The 6 long vectors are within the right hexagon with vertices, whose magnitude does not exceed the inscribed circle radius of the right hexagon. Therefore, the condition for the converter to realize SVPWM modulation is that the amplitude of a given space voltage vectorAs can be seen from the calculation of the formula (1), the modulation m is less than or equal to 0.907.
When the three-phase balance drop fault occurs to the grid voltage, the amplitude value | V of the space voltage vector is given*If the | is reduced, the modulation degree m is reduced and the system control margin is increased according to the formula 1; when the three-phase balance sudden-rise fault occurs to the grid voltage, | V*If | rises, the modulation m increases accordingly. When m is larger than 0.907, the system enters an overmodulation region, and the grid-side converter is in an uncontrollable state, so that the stable operation of the grid-side converter is seriously damaged. Therefore, when sudden rise is stable in a high-pressure state, it is necessary to suppress the rise of V or raise V using a certain control strategy as shown in equation (1)dcThereby, saturation of the modulation degree m is suppressed and the modulation degree m is controlled within the modulation range.
Inductive reactive power compensation control
FIG. 4a is a grid-side converter AC side vector relationship diagram under the condition of sudden rise of grid voltage, FIG. 4b is an AC side vector relationship diagram under the condition of stable grid voltage sudden rise and grid-side converter inductive reactive power compensation control, wherein E is a grid electromotive force vector, V is a grid-side converter AC voltage measurement vector, I is a grid-side converter grid-connected current vector, and I isdAnd IqD-axis reactive and q-axis active components of the grid-connected current vector I, respectively, wherein I is in the state of unit power factord0, XI is AC side filter of network side converterThe vector of the voltage drop across the wave inductance.
From fig. 4a, the following relationship can be obtained:
and
when the voltage of the power grid rises suddenly, the electromotive force of the power grid rises from E to E/I.e. E/>E, obtainable according to formula (2), V/>V, i.e. the inverter output voltage V, rises with the sudden rise of the grid voltage, so that damage to the grid-side converter from the sudden rise of the grid voltage can also be seen.
By combining the formula (1) and the formula (2), the following relationship can be obtained:
when the electric potential of the power grid is increased from E to E/By increasing the inductive reactive current IdAn orthogonal voltage drop XI can be generated across the filter inductor on the ac sided(XI indicated in FIG. 4b/Is XIdAnd XIqThe amount of the compound (c) of (c),) Therefore, the rising of the alternating-current voltage V of the grid-side converter is effectively inhibited, the dropping amplitude of the grid voltage is reduced, and the system is favorably and smoothly transited a sudden rise area of the grid voltage. And, at the active current IqWithout change, reactive current IdThe increase of the modulation factor m will reduce the modulation factor m of the converter; in addition, the active current I is reducedqMake the filter inductance voltage drop XIqThe saturation of the modulation m can be suppressed by reducing.
② direct current voltage control
In order to realize linear modulation of the grid-side converter, the grid voltage amplitude | E | and the DC-side voltage minimum value VdcminThe following relationship should be satisfied:
the control algorithm to be satisfied under the strategy is as follows:
wherein,is a given value of the DC side voltage of the grid side converterdc0The method comprises the steps that under a normal condition, a direct-current side voltage given initial value is calculated according to the nominal voltage of a power grid and the voltage amplitude of a motor stator; Δ V is the given increase of the DC side voltage, mainly due to the inductor drop XI of the maximum active currentqTo determine; vdcmaxThe maximum value of the dc side voltage is determined by the dc bus capacitance and the rated withstand voltage level of the power device.
When in useAt the moment, the input voltage at the alternating current side of the grid-side converter is in a controllable state, and the given value of the voltage at the direct current side is an initial value Vdc0(ii) a When in useWhen the input voltage of the network side is in an uncontrollable state, the direct current voltage needs to be increased to inhibit the saturation of the modulation degree m, and the given value of the voltage of the direct current side is increased to be higher than the value(ii) a When in useWhen the voltage set value of the DC side to be increased exceeds the maximum value of the DC voltage which can be endured by the system, the DC side is maintained at the maximum value Vdcmax。
In addition, the crowbar circuit of the full-power wind power system can respond to the detected direct-current voltage value u in the fault ride-through response process of grid drop or sudden risedcAnd a set width (u) of hysteresis loop of direct current voltagedc_maxAnd udc_min) And performing Bang-Bang control to feed redundant energy to the direct current side from the unloader side, and effectively inhibiting the rise of a direct current voltage pump caused by sudden rise of a power grid so as to stabilize the direct current voltage within a set safety threshold range. In order to reduce the operating frequency of a crowbar and reduce the voltage and current stress of a crowbar power switch device, a machine side converter is switched into a power limiting operation mode from a normal power or torque tracking mode, and the maximum power amplitude limit of the machine sideEqual to the active power P actually output by the network sideq_grid. In order to avoid the increase of mechanical stress of the wind turbine and the transmission chain caused by larger torque pulsation of the generator,set to be not less than rated power P of generatormotor40% of the total. The corresponding computational expression is as follows:
furthermore, it is considered that when the grid voltage has three-phase balance drop or sudden rise fault, the direct current supporting voltage u will be caused due to power mismatch or reverse energy flow from the grid to the direct current sidedcIf the grid-side converter continues to adopt the dc voltage outer loop control to stabilize the dc voltage at this time, the grid-connected current is inevitably increased. To prevent excessive instantaneous currentAnd if the bridge arm side current of the grid-side converter exceeds the safety threshold range, forcibly blocking a power switch tube driving signal of the grid-side converter.
According to the above description, the embodiment of the method judges and identifies different fault types of the power grid voltage, adopts a corresponding control strategy, and performs capacitive reactive power compensation control on the grid-side converter when the three-phase balance drop and drop stability of the power grid voltage occur, so that a certain restraining effect on the power grid drop is achieved, and the LVRT is realized; when three-phase balance sudden rise and sudden rise stability occur to the voltage of the power grid, inductive reactive power compensation control is carried out on the grid-side converter, so that a certain restraining effect is achieved on the sudden rise of the power grid, HVRT is achieved, meanwhile, the inductive reactive power compensation control can restrain the modulation degree from tending to saturation by restraining the sudden rise of the power grid, the grid-side converter can stably run in a modulation area, and the problems in the prior art are solved.
Referring to fig. 5, an embodiment of the present invention further discloses a grid fault ride-through device for a full-power wind power system, so that the full-power wind power system can smoothly bridge a three-phase balanced drop or swell region of a grid voltage, including:
the fault diagnosis unit 51 is used for carrying out fault diagnosis on the grid voltage of the full-power wind power system;
the low voltage ride through unit 52 is configured to detect whether the grid voltage falls stably in a low voltage state in real time after the three-phase balance drop fault of the grid voltage is diagnosed; when the grid voltage is detected to drop stably in a low-voltage state, capacitive reactive power compensation control is carried out on the grid-side converter according to the dropping amplitude of the grid voltage;
the high voltage ride through unit 53 is configured to detect whether the grid voltage suddenly rises stably in a high voltage state in real time after the three-phase balance sudden rise fault of the grid voltage is diagnosed; when the sudden rise and stability of the voltage of the power grid under a high-voltage state are detected, judging whether the grid-side converter is in a modulation state or not; if the grid-side converter is in a modulation state, performing inductive reactive power compensation control on the grid-side converter according to the sudden rise amplitude of the grid voltage; and if the grid-side converter is in an overmodulation state, forcibly blocking a power switch tube driving signal of the grid-side converter.
Therein, still referring to fig. 5, the fault diagnosis unit 51 includes:
the amplitude obtaining unit 511 is used for calculating the amplitude of the positive sequence voltage of the power grid by adopting a double-synchronous coordinate system decoupling software phase-locked loop technology;
the fault determination unit 512 is configured to determine that a three-phase balance drop fault occurs in the grid voltage when the amplitude of the grid positive sequence voltage is lower than the lower limit of the normal amplitude; and when the amplitude of the positive sequence voltage of the power grid is higher than the upper limit of the normal amplitude, judging that the three-phase balance sudden-rise fault occurs to the power grid voltage.
Preferably, the apparatus further comprises: and the modulation unit 54 is configured to modulate the machine side converter and the grid side converter in the full-power wind power system in a space vector pulse width modulation manner before performing fault diagnosis on the grid voltage of the full-power wind power system.
As a single option, the high voltage ride through unit 53 is further configured to perform dc voltage conversion control on the grid-side converter after the grid-side converter is determined to be in the modulation state.
In summary, in order to ensure that the full-power wind power system smoothly crosses the three-phase balance drop or swell area of the power grid voltage, the invention judges and identifies different fault types of the power grid voltage, adopts a corresponding control strategy, and carries out capacitive reactive power compensation control on the grid-side converter when the three-phase balance drop and drop stability of the power grid voltage occur, thereby playing a certain role in inhibiting the power grid drop and realizing LVRT; when three-phase balance sudden rise and sudden rise stability occur to the voltage of the power grid, inductive reactive power compensation control is carried out on the grid-side converter, so that a certain restraining effect is achieved on the sudden rise of the power grid, HVRT is achieved, meanwhile, the inductive reactive power compensation control can restrain the modulation degree from tending to saturation through restraining the sudden rise of the power grid, the grid-side converter can stably run in a modulation area, and the problems in the prior art are solved.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the embodiments. Thus, the present embodiments are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A grid fault ride-through method of a full-power wind power system is characterized by comprising the following steps:
carrying out fault diagnosis on the power grid voltage of the full-power wind power system;
after the three-phase balance drop fault of the power grid voltage is diagnosed, detecting whether the power grid voltage drops stably in a low-voltage state in real time; when the grid voltage is detected to drop stably in a low-voltage state, capacitive reactive power compensation control is carried out on the grid-side converter according to the dropping amplitude of the grid voltage;
after the three-phase balance sudden rising fault of the power grid voltage is diagnosed, detecting whether the power grid voltage suddenly rises stably in a high-voltage state in real time; when the sudden rise and stability of the voltage of the power grid under a high-voltage state are detected, judging whether the grid-side converter is in a modulation state or not; if the grid-side converter is in a modulation state, performing inductive reactive power compensation control on the grid-side converter according to the sudden rise amplitude of the grid voltage; if the grid-side converter is in an overmodulation state, forcibly blocking a power switch tube driving signal of the grid-side converter;
in the fault ride-through response process of power grid drop or sudden rise, a crowbar circuit in the full-power wind power system performs Bang-Bang control according to a detected direct-current voltage value and a set direct-current voltage hysteresis loop width, so that redundant energy fed into a direct-current side from an unloader side is used, the rise of a direct-current pressure pump caused by the sudden rise of the power grid is effectively inhibited, and the direct-current voltage is stabilized in a set safety threshold range; in order to reduce the action frequency of a crowbar and reduce the voltage and current stress of a crowbar power switch device, the converter on the machine side is controlled to be switched into a power-limiting operation mode from a power or torque tracking mode, and meanwhile, the maximum power amplitude limit of the machine side is set to be equal to the active power actually output by the network side.
2. The method of claim 1, wherein the fault diagnosing the grid voltage of the full power wind power system comprises:
calculating to obtain the amplitude of the positive sequence voltage of the power grid by adopting a double-synchronous coordinate system decoupling software phase-locked loop technology;
when the amplitude of the positive sequence voltage of the power grid is lower than the lower limit of the normal amplitude, judging that the three-phase balance drop fault occurs to the power grid voltage; and when the amplitude of the positive sequence voltage of the power grid is higher than the upper limit of the normal amplitude, judging that the three-phase balance sudden-rise fault occurs to the power grid voltage.
3. The method according to claim 1 or 2, wherein before performing fault diagnosis on the grid voltage of the full-power wind power system, the method further comprises: and modulating the machine side converter and the grid side converter in the full-power wind power system by adopting a space vector pulse width modulation mode.
4. The method according to claim 1 or 2, further comprising, after determining that the grid-side converter is in the modulation state: and performing direct-current voltage conversion control on the grid-side converter.
5. The method according to claim 1 or 2, wherein after diagnosing the grid voltage for a three-phase balance drop fault and after diagnosing the grid voltage for a three-phase balance swell fault, the method further comprises:
judging whether the bridge arm side current of the grid side converter is within a safety threshold range;
and when the bridge arm side current of the grid-side converter exceeds the safety threshold range, forcibly blocking the power switch tube driving signal of the grid-side converter.
6. A grid fault ride-through device of a full-power wind power system is characterized by comprising:
the fault diagnosis unit is used for carrying out fault diagnosis on the power grid voltage of the full-power wind power system;
the low-voltage ride-through unit is used for detecting whether the power grid voltage falls stably in a low-voltage state in real time after the power grid voltage is diagnosed to have a three-phase balance falling fault; when the grid voltage is detected to drop stably in a low-voltage state, capacitive reactive power compensation control is carried out on the grid-side converter according to the dropping amplitude of the grid voltage;
the high voltage ride through unit is used for detecting whether the power grid voltage suddenly rises stably in a high voltage state in real time after the power grid voltage is diagnosed to have a three-phase balance sudden rise fault; when the sudden rise and stability of the voltage of the power grid under a high-voltage state are detected, judging whether the grid-side converter is in a modulation state or not; if the grid-side converter is in a modulation state, performing inductive reactive power compensation control on the grid-side converter according to the sudden rise amplitude of the grid voltage; if the grid-side converter is in an overmodulation state, forcibly blocking a power switch tube driving signal of the grid-side converter;
in the fault ride-through response process of power grid drop or sudden rise, a crowbar circuit in the full-power wind power system performs Bang-Bang control according to a detected direct-current voltage value and a set direct-current voltage hysteresis loop width, so that redundant energy fed into a direct-current side from an unloader side is used, the rise of a direct-current pressure pump caused by the sudden rise of the power grid is effectively inhibited, and the direct-current voltage is stabilized in a set safety threshold range; in order to reduce the action frequency of a crowbar and reduce the voltage and current stress of a crowbar power switch device, the low-voltage ride-through unit and the high-voltage ride-through unit are also used for controlling the machine side converter to be switched into a power-limiting operation mode from a power or torque tracking mode, and meanwhile, the maximum power amplitude limit of the machine side is set to be equal to the active power actually output by the network side.
7. The apparatus according to claim 6, wherein the fault diagnosis unit comprises:
the amplitude acquisition unit is used for calculating the amplitude of the positive sequence voltage of the power grid by adopting a double-synchronous coordinate system decoupling software phase-locked loop technology;
the fault determination unit is used for determining that the three-phase balance drop fault occurs to the power grid voltage when the amplitude of the power grid positive sequence voltage is lower than the lower limit of the normal amplitude; and when the amplitude of the positive sequence voltage of the power grid is higher than the upper limit of the normal amplitude, judging that the three-phase balance sudden-rise fault occurs to the power grid voltage.
8. The apparatus of claim 6 or 7, further comprising: and the modulation unit is used for modulating the machine side converter and the grid side converter in the full-power wind power system by adopting a space vector pulse width modulation mode before fault diagnosis is carried out on the grid voltage of the full-power wind power system.
9. The apparatus according to claim 6 or 7, wherein the high voltage ride through unit is further configured to perform dc-to-dc voltage control on the grid-side converter after determining that the grid-side converter is in the modulation state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510080562.6A CN104617584B (en) | 2015-02-12 | 2015-02-12 | A kind of fault ride-through of power grid method and apparatus of total power wind power system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510080562.6A CN104617584B (en) | 2015-02-12 | 2015-02-12 | A kind of fault ride-through of power grid method and apparatus of total power wind power system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104617584A CN104617584A (en) | 2015-05-13 |
| CN104617584B true CN104617584B (en) | 2017-07-28 |
Family
ID=53151924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510080562.6A Active CN104617584B (en) | 2015-02-12 | 2015-02-12 | A kind of fault ride-through of power grid method and apparatus of total power wind power system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104617584B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105024402A (en) * | 2015-07-20 | 2015-11-04 | 国家电网公司 | High voltage ride-through method of doubly-fed wind turbine generator set |
| JP6451722B2 (en) * | 2016-11-25 | 2019-01-16 | 株式会社安川電機 | Power generation system, power conversion system, power conversion device, and power conversion method |
| CN107561346B (en) * | 2017-07-27 | 2021-09-10 | 佛山市华葆电源设备有限公司 | Method for rapidly detecting three-phase mains supply voltage abnormity |
| CN108462201B (en) * | 2018-02-07 | 2021-04-20 | 东方电气风电有限公司 | Method for improving wide rated voltage and high voltage ride through range of doubly-fed wind turbine generator |
| CN108667033A (en) * | 2018-04-20 | 2018-10-16 | 中国东方电气集团有限公司 | Wind electric converter high voltage crossing control method and device based on Hysteresis control |
| CN113131510B (en) * | 2020-01-16 | 2022-09-27 | 新疆金风科技股份有限公司 | High voltage ride through control method and system for wind power plant, MMC and machine side converter |
| CN111952982A (en) * | 2020-07-28 | 2020-11-17 | 中冶赛迪电气技术有限公司 | Energy storage converter regulator saturation prevention control method during low voltage ride through recovery |
| CN113258585B (en) * | 2021-05-14 | 2023-01-31 | 明阳智慧能源集团股份公司 | Wind turbine generator system fault voltage ride-through reactive power control method, system, medium and equipment |
| CN114914913B (en) * | 2022-06-22 | 2024-03-12 | 广东工业大学 | Unit combination method considering driving stability constraint of converter |
| CN116436043B (en) * | 2023-06-13 | 2023-10-20 | 国网江西省电力有限公司电力科学研究院 | Asymmetric fault ride-through control method for multiple converters |
| CN117092501B (en) * | 2023-10-18 | 2024-05-14 | 西安高压电器研究院股份有限公司 | Fracture joint voltage test loop for switching device and measuring method |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7709972B2 (en) * | 2007-08-30 | 2010-05-04 | Mitsubishi Heavy Industries, Ltd. | Wind turbine system for satisfying low-voltage ride through requirement |
| CN102088191B (en) * | 2010-12-22 | 2012-12-12 | 阳光电源股份有限公司 | Method and system for cooperatively controlling low voltage ride through of full-power fan converter |
| CN102355009B (en) * | 2011-10-11 | 2013-09-04 | 国电联合动力技术有限公司 | Method by utilizing doubly-fed generator to realize high-voltage ride through of wind power generating set and system thereof |
| CN103227477A (en) * | 2013-03-27 | 2013-07-31 | 许继集团有限公司 | High voltage ride through control method for double-fed wind generator |
| CN103311957B (en) * | 2013-06-28 | 2015-10-07 | 阳光电源股份有限公司 | A kind of net side converter control method and system |
| CN103368184B (en) * | 2013-07-19 | 2014-12-10 | 国家电网公司 | Control method for large wind field reactive-load compensation equipment in low voltage ride through |
-
2015
- 2015-02-12 CN CN201510080562.6A patent/CN104617584B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN104617584A (en) | 2015-05-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104617584B (en) | A kind of fault ride-through of power grid method and apparatus of total power wind power system | |
| CN105375523B (en) | A kind of wind power full power current transformer high voltage crossing control method | |
| US9425726B2 (en) | Fault-tolerant wind energy conversion system | |
| US9331487B2 (en) | Method and apparatus for islanding detection for grid tie converters | |
| Mohseni et al. | Fault ride-through capability enhancement of doubly-fed induction wind generators | |
| EP2506422B1 (en) | Circuits for dc energy stores | |
| US10236793B2 (en) | Grid connection power conversion device and output current control method thereof | |
| US20150311696A1 (en) | System and method for protecting electrical machines | |
| CN101702583B (en) | Method for controlling direct-drive wind power generation convertor | |
| CN108718094A (en) | A method of it improving large-sized photovoltaic system low-voltage and passes through performance | |
| TW201534019A (en) | Control device and method for controlling power conversion unit | |
| CN106505620A (en) | A kind of transient state reconfiguration system for improving double-fed fan trouble ride-through capability and control method | |
| CN103972924B (en) | Permanent magnet direct-drive wind power system low voltage traversing control method under unbalanced electric grid voltage | |
| CN110601572B (en) | Compensation instruction current obtaining method, device and equipment | |
| CN108123486A (en) | The control method and device of wind electric converter low voltage crossing | |
| CN105633997A (en) | Wind generating set voltage crossing control method and device | |
| CN116865541A (en) | Grid-structured inverter hybrid current limiting method under grid symmetrical short circuit fault | |
| CN108123485A (en) | The control method and device of wind electric converter high voltage crossing | |
| CN105633999A (en) | High-voltage crossing control method and device under imbalanced sudden rise of power grid voltage | |
| CN105633998A (en) | Wind generating set high-voltage crossing control method and device | |
| CN107681692B (en) | Alternating current excitation power supply fault ride-through control system | |
| CN111130331B (en) | Overvoltage suppression control method for flexible direct-current transmission wind power grid-connected converter | |
| CN110768296B (en) | System for improving low voltage ride through capability of double-fed pumped storage unit and control method thereof | |
| JP2010035418A (en) | Method for controlling wind power generation system | |
| CN111509767A (en) | High voltage ride through control method for wind power double-fed converter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |