CN110912158A - Multi-terminal flexible direct-current power transmission system frequency stability control method with wind power participating in frequency modulation - Google Patents
Multi-terminal flexible direct-current power transmission system frequency stability control method with wind power participating in frequency modulation Download PDFInfo
- Publication number
- CN110912158A CN110912158A CN201911287747.9A CN201911287747A CN110912158A CN 110912158 A CN110912158 A CN 110912158A CN 201911287747 A CN201911287747 A CN 201911287747A CN 110912158 A CN110912158 A CN 110912158A
- Authority
- CN
- China
- Prior art keywords
- frequency
- power
- wind turbine
- converter station
- rotating speed
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 43
- 230000005540 biological transmission Effects 0.000 title claims abstract description 36
- 230000008859 change Effects 0.000 claims abstract description 28
- 238000011084 recovery Methods 0.000 claims description 27
- 230000004044 response Effects 0.000 claims description 20
- 230000002829 reductive effect Effects 0.000 claims description 19
- 230000009467 reduction Effects 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 8
- 238000005259 measurement Methods 0.000 claims description 7
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 230000002411 adverse Effects 0.000 claims description 4
- 230000003111 delayed effect Effects 0.000 claims description 3
- 230000006698 induction Effects 0.000 claims description 3
- 238000011217 control strategy Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- 230000033228 biological regulation Effects 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
- H02J2003/365—Reducing harmonics or oscillations in HVDC
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
Abstract
The invention discloses a frequency stability control method of a multi-terminal flexible direct-current power transmission system with wind power participating in frequency modulation, belongs to the technical field of control of flexible direct-current power transmission systems, and aims to solve the problems that when a receiving-terminal alternating-current system or a transmitting-terminal alternating-current system fails to cause frequency change, power support of the two-terminal alternating-current system is low, and the system frequency is unstable. The method comprises the steps of determining a multi-terminal flexible direct current transmission system structure accessed by wind power, determining that a control mode of a receiving end converter station is a direct current voltage droop control method, introducing power increment related to power grid frequency into the receiving end converter station, determining a control mode of a sending end converter station, introducing additional frequency control into the sending end converter station, adjusting the rotating speed of a fan by a wind power unit according to the frequency change of the sending end converter station, and outputting active power to support power of the sending end system. The invention is applied to the frequency change caused by the failure of the receiving end alternating current system or the transmitting end alternating current system, can improve the power supporting capability of the two end alternating current systems and maintain the stable operation of the systems.
Description
Technical Field
The invention belongs to the technical field of direct current transmission system control, and particularly relates to a multi-terminal flexible direct current transmission system frequency stability control method with wind power participating in frequency modulation.
Background
The consumption and transmission problems of new energy sources are an important ring in utilization of the new energy sources, a multi-terminal flexible direct-current power transmission system of the voltage source converter has the characteristics of multi-terminal power transmission and multi-drop point power reception, the transmission energy is large, active power and reactive power can be independently controlled, unique technical advantages are achieved in the aspects of solving the problems of new energy generation dispersity, being far away from a load center and the like, and the key for solving the problems is achieved.
Compared with a synchronous generator, the flexible direct-current transmission system is used as a power supply of a power grid, and has no rotation inertia in a traditional control mode, however, when the flexible direct-current transmission power occupies a large proportion to the capacity of a transmitting-receiving end alternating-current power grid, the accident support capability exerted between the alternating-current power grids should be considered, one outstanding advantage of the flexible direct-current transmission is that the transmitted active power and the transmitted reactive power can be quickly and accurately adjusted in the level of tens of milliseconds, if the controlled quick adjustment capability can be exerted, the safety stability of the whole interconnected system can be improved, the accident transmission between the systems can be avoided, meanwhile, the flexible direct-current transmission system effectively decouples the alternating-current systems at two ends, so that when the alternating-current system at one end is subjected to frequency instability, the alternating-current system at the other end cannot provide power support, and the frequency stability.
The doubly-fed variable speed wind turbine generator has two typical operating states, namely supersynchronous operation and subsynchronous operation, when the wind speed is high, the wind turbine generator operates in the supersynchronous state, the rotating speed of a rotor is higher than the synchronous rotating speed, the slip ratio s is less than 0, and the stator and the rotor simultaneously provide power output for a system, a large amount of rotational kinetic energy is stored in the rotor of the doubly-fed variable speed wind turbine generator under the operating state, because the rotating speed of the rotor is controlled by a rotor-side converter, the part of the kinetic energy can not be released when the system frequency is reduced only by weak electromagnetic coupling between the stator and the rotor, the inhibition effect of the kinetic energy on the system frequency can not be reflected, on the contrary, when the wind speed is low, the wind turbine generator operates in the subsynchronous state, the rotating speed of the rotor is lower than the synchronous rotating speed, the slip ratio s is more than 0, the, similarly, because the rotating speed of the rotor of the doubly-fed variable-speed wind turbine generator is controlled by the converter, the rotor absorbs less electromagnetic power and the rotating speed is improved less by depending on the coupling relation between the stator and the rotor, the rotor can only absorb less system power, and the inhibiting effect on the system frequency increase is not obvious.
In conclusion, although the double-fed wind turbine generator has excellent active and reactive decoupling control performance, the rotor speed of the double-fed wind turbine generator controlled by the frequency converter and the system frequency do not have a coupling relation, the rotor kinetic energy of the wind turbine generator is hidden, and the double-fed wind turbine generator does not have the capability of responding to the system frequency change.
In the prior art, a control strategy for a wind turbine generator to participate in the frequency of an electric power system mainly includes the following two modes:
(1) the method comprises the following steps of power standby control, wherein the power standby control is used for controlling a wind turbine generator to carry out load shedding operation, so that a certain power standby is reserved and system frequency modulation is supported by the power standby control, at the moment, the wind turbine generator works at a suboptimal power tracking point, and the method comprises the following two main steps: pitch angle control and rotor speed control.
The pitch angle control of the wind turbine generator is that when the wind turbine generator is in steady-state operation, the pitch angle of the fan is properly increased, the maximum wind power tracking is abandoned, the change rate of the system frequency is introduced as the pitch angle change of the input control fan, the system frequency is reduced after falling, the wind turbine generator is recovered to the maximum wind power tracking state, the captured mechanical power is increased, extra power support can be provided for the system, but the regulation speed of the blade angle control is slow, mechanical abrasion exists, the wind turbine generator rotation speed control is that the maximum power tracking of the wind turbine generator is abandoned to obtain the stable and safe system frequency, namely a wind turbine generator load reduction operation control strategy, the method modifies the maximum power tracking curve of the wind turbine generator, the realization mode is complex, and the wind turbine generator generates an electric phenomenon when the wind turbine generator operates in real time, in conclusion, the power standby control leads the output of the fan to be smaller than, thereby leaving a certain spare capacity.
Under a general condition, in order to improve the wind energy utilization rate, the doubly-fed wind turbine generator operates under the maximum power tracking working condition, so that when the system frequency is reduced, the doubly-fed wind turbine generator cannot provide extra active support for the system and cannot participate in system frequency adjustment.
(2) The rotor kinetic energy control adopts the principle that a frequency control link is added in an active power control system of a wind turbine generator to realize the interconversion of the rotational kinetic energy and the electromagnetic power contained in a fan rotor, so that the rotational kinetic energy participates in the frequency adjustment of the system to maintain the frequency stability of the system, and the specific realization method of the rotor kinetic energy control mainly comprises virtual inertia control, droop control and comprehensive inertia control.
Although the rotating speed of the doubly-fed wind turbine generator has a large variation range, and the rotor stores large rotating energy, the kinetic energy stored in the rotor is limited, namely the rotating speed of the rotor cannot be infinitely reduced, when the rotating speed of the rotor is reduced to a lower limit value, the wind turbine generator immediately exits from frequency modulation, at the moment, the rotor needs to recover the rotating speed, the wind turbine generator needs to absorb power to a system in the process, adverse effects are brought to the frequency response of the system, and the secondary reduction of the system frequency can be caused in the serious process.
Based on the problems in the background art, the technical proposal in the prior art is a method for controlling the frequency stability of a multi-terminal flexible direct-current power transmission system with wind power participating in frequency modulation.
Disclosure of Invention
The invention aims to provide a frequency stability control method of a multi-terminal flexible direct-current transmission system with wind power participating in frequency modulation, and aims to solve the problems that when a receiving-terminal alternating-current system or a transmitting-terminal alternating-current system fails to cause frequency change, the power support of the two-terminal alternating-current system is low, and the system frequency is unstable.
In order to solve the problems, the technical scheme of the invention is as follows:
the method for controlling the frequency stability of the multi-terminal flexible direct-current power transmission system with wind power participating in frequency modulation comprises the following steps:
step 1: determining a direct current transmission system structure accessed by wind power:
the method comprises the following steps that a wind power field WF of a wind turbine generator is connected with a sending end converter station VSC1, a receiving end alternating current grid AC1 is connected with a receiving end converter station VSC2, a receiving end alternating current grid AC2 is connected with a receiving end converter station VSC3, and the sending end converter station VSC1, the receiving end converter station VSC2 and the receiving end converter station VSC3 are connected with one another;
step 2: determining the control mode of the receiving end converter station VSC2 and the VSC3 as a direct-current voltage droop control method;
and step 3: introducing power increment related to the grid frequency at the receiving end converter VSC2 and the VSC 3;
and 4, step 4: determining a control mode of the VSC1 of the sending end converter station;
and 5: additional frequency control is introduced at the sending end converter station VSC 1:
step 6: the wind turbine generator set adjusts the rotating speed of the fan according to the frequency change delta f of the VSC1 of the sending end converter station, and outputs active power to support the power of the sending end system.
Further, step 6 is specifically decomposed into the following steps:
step 601: the kinetic energy stored in the rotor of the wind turbine can be expressed as
In the formula:Jthe rotational inertia of the impeller and the generator;ωthe rotating speed of the rotor of the wind turbine generator set;
step 602: calculating kinetic energy absorbed or released by the wind turbine generator when the frequency of the power grid changes;
when the grid frequency is fromf 0Change tof 1When the rotor speed is higher than the set valueω 0 Change toω 1 The rotational kinetic energy absorbed or released by the wind turbine generator is as follows:
step 603: converting kinetic energy stored by the rotating part of the wind turbine generator into frequency modulation power under frequency modulation time by using formula (5), as shown in formula (6):
in the formula:ηconversion efficiency for converting kinetic energy into electric energy;
∆P 1a compensation power responsive to the inertia;
∆tis the inertia response duration;
the active power output of the unit can be only temporarily increased or reduced through the conversion of the kinetic energy of the rotor, and because the speed of the rotor of the unit is limited, the duration of the inertia response of the unit is strictly limited in order to avoid triggering the fault of the unit, and the duration is generally set to 10 s;
the kinetic energy release control process of the rotor of the wind turbine generator set is divided into a power supporting stage and a rotating speed recovery stage; when the frequency of a power grid is reduced, the wind turbine generator set provides active power support by increasing electromagnetic torque, in the process, the rotating speed is rapidly reduced, when the rotating speed is reduced to a lower limit value, the fan quits frequency modulation, at the moment, larger deviation of the frequency is caused, and when the frequency is more serious, secondary falling of the system frequency is caused; the rotating speed recovery process is carried out when the system frequency is not recovered to be stable, so that the reduction of the active power output by the wind turbine generator and the increase of the system load caused by the rotating speed recovery cause a 'superposition effect' on the reduction of the system frequency, the deviation of the system frequency is increased, and the frequency response characteristic is poor; therefore, in order to solve the adverse effect of the rotation speed recovery on the frequency response of the system, the recovery of the rotation speed can be delayed by introducing constant power, and the stability of the system frequency is improved;
the power-speed relationship of the doubly-fed wind turbine is shown in fig. 6, wherein,P Mrepresenting the mechanical power delivered by the wind turbine to the doubly fed induction generator,P MPPTrepresenting an active power reference value under the MPPT algorithm;
step 604: when the rotor speed is lower than the minimum valueω min（ω minGenerally taking the value as 0.7 pu), entering a rotating speed recovery process, and delaying the rotating speed recovery of the wind turbine generator by additional power;
since the virtual inertial control can provide a power response to the system quickly in response to changes in the rate of change of frequency, the additional power is designed to:
in the formula:K dis a differential coefficient;
step 605: when the system frequency is recovered, willPGradually reducing to 0, and connecting a wind turbine generator set to recover the rotating speed;
in summary, a doubly-fed wind turbine frequency control scheme based on rotor kinetic energy control as shown in fig. 7 may be adopted for the wind turbine; the frequency control system mainly comprises a frequency control module, a rotating speed protection system module and a rotating speed recovery starting module; a frequency control module: the module is used for transmitting a frequency-adjusted power signal; after obtaining the frequency deviation signal, obtaining the maximum frequency deviation and then obtaining the constant additional power according to the formula (7)P(ii) a The low-pass filter is used for eliminating the interference of frequency measurement noise;
the rotating speed recovery starting module: the module is used for enabling the rotating speed to be quickly recovered to the optimal operation state; after constant additional power control is introduced, the doubly-fed wind turbine generator operates at a lower rotating speed (relative optimal rotating speed) after releasing the kinetic energy of a rotor, and deviates from a maximum power tracking point; in order to improve the wind energy utilization rate, after the system frequency is recovered to be stable, the rotating speed still needs to be recovered, so that the double-fed wind turbine generator set returns to the maximum power tracking point again;
the rotating speed protection system module: the module has the function of avoiding the influence on the safe and stable operation of the double-fed wind turbine generator system caused by the excessively low rotor speed reduction when the double-fed wind turbine generator system participates in system frequency modulation; when the rotor speed is lower than the minimum valueω minAnd when the system is started, the rotating speed protection system is started, so that the wind turbine generator does not participate in system frequency control any more.
Further, step 2 specifically comprises:
droop control is combined with power control and voltage control, and an inner loop current reference value i is generated according to a P-V characteristic curvedrefThe calculation formula is shown as formula (1):
in the formula, Udcref、UdcRespectively direct current reference voltage and direct current measurement voltage;
Prefp is an active power reference value and an active power actual value of the current converter respectively;
Kp、Kiproportional coefficient and integral coefficient of PI regulator;
KDis the droop slope;
1/s represents the integral.
Further, step 3 specifically comprises:
adding a power increment delta Pref related to the measured frequency fac of the alternating current network on the basis of a converter active power reference value Pref set by a receiving end converter VSC2 and a VSC3, wherein the calculation mode is shown as a formula (2):
in the formula (f)acrefRated frequency for the AC power grid;
facactually measuring the frequency of the alternating current network;
Kfis a scaling factor for frequency control.
Further, step 4 specifically includes: when the wind power plant is connected to the flexible direct current transmission system, the control target of the sending end converter station is to provide rated alternating voltage and frequency as a reference power supply of a wind turbine converter, and therefore grid connection of the wind power plant is achieved.
Further, step 5 specifically comprises:
detecting the direct-current side voltage of the VSC1 receiving end converter station of the sending end converter station and according to the difference U of the direct-current side voltage deviating from the rated voltageDCCalculating the frequency deviation, and converting the change of the direct current voltage into the frequency change delta f of the sending end converter station through a control parameter Kv, wherein the calculation mode is shown as formula (3):
(3)
in the formula, Kv is a control parameter and reflects the proportion of the frequency deviation of the sending end converter station to the direct-current voltage deviation;
ΔUDCis the variation value of the direct current voltage.
Further, the sending end converter station VSC1, the receiving end converter station VSC2, and the receiving end converter station VSC3 are all flexible direct current converter stations.
The invention has the following beneficial effects:
(1) the invention responds to the frequency change of the receiving end alternating current system by introducing additional frequency into the traditional control strategy of the converter station of the flexible direct current transmission system, the frequency change of the receiving end alternating current system is transmitted to the sending end system through the change of the direct current voltage, so that the wind turbine generator can respond to the frequency change of the receiving end alternating current system and carry out power support on the receiving end alternating current system, and similarly, when the frequency of the fan side changes, the frequency of the converter station can be adjusted by additional frequency control of the flexible direct current system converter station, and through the relationship between the frequency of the artificial coupling network side and the frequency of the wind farm side, can realize the aim of mutual support of the alternating current systems in a fault state, assist the adjustment of frequency, enhance the stability of the system, meanwhile, the wind turbine generator is controlled by introducing constant power into a traditional control strategy, so that the secondary frequency drop caused by the fact that the wind turbine generator exits from frequency modulation can be prevented.
(2) The invention is applied to frequency change caused by the failure of a receiving end alternating current system or a transmitting end alternating current system, and the converter station of the flexible direct current transmission system and the wind turbine generator set jointly participate in frequency regulation, thereby improving the power support capability of the alternating current systems at two ends, maintaining the stable frequency of the system and enabling the system to stably run.
Drawings
FIG. 1 is a schematic diagram of a three-terminal flexible DC power transmission system;
FIG. 2 is a control block diagram of a receiving end converter station;
FIG. 3 is a block diagram of additional frequency controlled DC droop control;
FIG. 4 is a block diagram of a transmitting end converter station control;
FIG. 5 is a block diagram of a control of a transmitting end converter station with additional frequency control;
FIG. 6 is a relation of power-rotation speed of a doubly-fed wind turbine;
FIG. 7 is a frequency control block diagram of a doubly-fed wind turbine generator based on rotor kinetic energy control.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 to 7, the method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with wind power participating in frequency modulation includes the following steps:
step 1: determining a direct current transmission system structure accessed by wind power:
the wind power field WF of the wind turbine generator is connected with the sending end converter station VSC1, the receiving end alternating current grid AC1 is connected with the receiving end converter station VSC2, the receiving end alternating current grid AC2 is connected with the receiving end converter station VSC3, and the sending end converter station VSC1, the receiving end converter station VSC2 and the receiving end converter station VSC3 are connected with one another.
Specifically, the method comprises the following steps: the sending end converter station VSC1, the receiving end converter station VSC2 and the receiving end converter station VSC3 are all flexible direct current converter stations.
Connection details refer to fig. 1.
Step 2: determining the control modes of the VSC2 and the VSC3 of the receiving end converter station:
using a DC voltage sag according toP-VCharacteristic curve generation inner loop current reference valuei drefThe calculation formula is shown as formula (1):
in the formula,U dcref、U dcrespectively direct current reference voltage and direct current measurement voltage;
P ref、Prespectively representing an active power reference value and an active power actual value of the current converter;
K p、K iproportional coefficient and integral coefficient of PI regulator;
K Dis the droop slope;
1/s represents the integral;
i.e. reactive currenti qrefThe value of (b) can be obtained by performing feedback control on the grid-connected point alternating voltage.
Under the action of PI regulator, when the actual value of active power flowing into AC sidePWhen increasing or decreasing, the voltage is measured by direct currentU dcAccording to the slopeK DAutomatically droop.
However, although the above control strategy can accomplish the power distribution without communication, since the flexible direct system has no inertia, it cannot respond to the frequency variation of the ac system, so it is necessary to introduce a frequency f measured by the ac networkacRelated power increment Δ Pref。
And step 3: converter active power reference value set at receiving end converter VSC2 and VSC3P refOn the basis of the frequency measuring circuit, a frequency measuring circuit is additionally arranged to measure the frequency of the alternating current networkf acRelated power increment Δ PrefThe calculation method is shown as formula (2):
in the formula,f acrefrated frequency for the AC power grid;
f acactually measuring the frequency of the alternating current network;
K fis a scaling factor for frequency control.
Referring to fig. 3: when the alternating current network of the receiving end alternating current network AC1 and the receiving end alternating current network AC2 measures the frequencyf acProportional coefficient controlled by additional frequency when sudden drop occursK fPerforming frequency control in response toActive power reference values of the receiving end converter stations VSC2 and VSC3P refTo which a positive power increment delta is addedP refAnd the VSC2 and the VSC3 of the receiving end converter station are promoted to output actual values of active powerPRegulating the actual frequency of the AC networkf acAnd the frequency instability is prevented.
Meanwhile, under the action of the control strategy, the actual value of the active power is obtainedPWhen increasing, the DC measurement voltageU dcWill correspondingly decrease, DC measures the voltageU dcThe falling of the wind power station is transmitted to the sending end converter station VSC1, and at this time, the sending end converter station VSC1 senses the information through the following control strategy to make corresponding adjustment and transmits the information to the wind turbine, so as to perform frequency control in cooperation with the receiving end converter stations VSC2 and VSC 3.
And 4, step 4: determining the control mode of the sending end converter station VSC 1:
when a wind power plant is connected to a flexible direct current transmission system, a control target of a sending end converter station is to provide rated alternating voltage and frequency as a reference power supply of a wind turbine converter, so that grid connection of the wind power plant is realized, and a control block diagram of a traditional sending end converter station is shown in fig. 4.
In order to enable the wind power plant to sense the change of the frequency of the alternating current system at the grid side, the frequency of the converter station at the sending end is in certain relation with the frequency of the power grid through the changed direct current voltage of the converter station at the sending end, so that the artificial coupling relation is realized, and the fans participate in frequency modulation together.
And 5: the sending end converter station VSC1 introduces additional frequency control:
introducing additional frequency control into the sending end converter station, and converting the change of the direct current voltage into the frequency change of the sending end converter station, wherein the formula (3) is as follows:
in the formula,K vfor controlling parameters, reflecting the proportion of the frequency deviation of the sending end converter station to the direct-current voltage deviation;
ΔU dcis the variation value of the direct current voltage.
By sensing the DC side voltage of the converter stationU dcAnd according to the difference delta from the rated voltageU dcCalculating the frequency additive quantity deltafAnd correcting the output power of the sending end converter so as to realize the control of the frequency of the wind power plant.
When the frequency of the receiving end converter station drops, the power of the receiving end converter flowing to the alternating current power grid can be increased, and meanwhile, the direct current voltage can be correspondingly reduced;
when the sending end converter station detects the drop of the direct current voltage, the output alternating current frequency of the sending end converter station is correspondingly reduced.
Step 6: the wind turbine generator set adjusts the rotating speed of the fan according to the frequency change delta f of the VSC1 of the sending end converter station, and outputs active power to support the power of a receiving end system.
The specific decomposition comprises the following steps:
step 601: the kinetic energy stored in the wind turbine rotor is expressed as:
in the formula:Jthe rotational inertia of the impeller and the generator;
ωthe rotating speed of the rotor of the wind turbine generator is shown.
Step 602: calculating the kinetic energy absorbed or released by the wind turbine generator when the frequency of the power grid changes:
when the grid frequency is fromf 0Change tof 1When the rotor speed is higher than the set valueω 0 Change toω 1 The rotational kinetic energy absorbed or released by the wind turbine generator is as follows:
step 603: converting kinetic energy stored by the rotating part of the wind turbine generator into frequency modulation power under frequency modulation time by using formula (5), as shown in formula (6):
in the formula:ω minconversion efficiency for converting kinetic energy into electric energy;
∆P 1a compensation power responsive to the inertia;
∆tis the inertia response duration.
The active output of the unit can be only temporarily increased or reduced through the conversion of the kinetic energy of the rotor, and because the speed of the rotor of the unit is limited, the duration of the inertia response of the unit is strictly limited to avoid triggering the fault of the unit, and is generally set to 10 s.
The kinetic energy release control process of the rotor of the wind turbine generator set is divided into a power supporting stage and a rotating speed recovery stage.
When the frequency of a power grid is reduced, the wind turbine generator set provides active power support by increasing electromagnetic torque, in the process, the rotating speed is rapidly reduced, when the rotating speed is reduced to a lower limit value, the fan quits frequency modulation, at the moment, the larger deviation of the frequency is caused, and when the frequency is more serious, the secondary falling of the system frequency is caused.
The rotating speed recovery process is carried out when the system frequency is not recovered to be stable, so that the reduction of the active power output by the wind turbine generator and the increase of the system load caused by the rotating speed recovery cause a 'superposition effect' on the reduction of the system frequency, the deviation of the system frequency is increased, and the frequency response characteristic is poor.
Therefore, in order to solve the adverse effect of the rotation speed recovery on the frequency response of the system, the recovery of the rotation speed can be delayed by introducing constant power, and the stability of the system frequency is improved.
The relation of the power and the rotating speed of the doubly-fed wind turbine generator is shown in figure 6,
wherein,P Mrepresenting the mechanical power delivered by the wind turbine to the doubly-fed induction generator;
P MPPTand representing the active power reference value under the MPPT algorithm.
Step 604: when the rotor speed is lower than the minimum valueω min（ω minGenerally 0.7 pu), the process of speed recovery will be entered, throughAnd the additional power delays the recovery of the rotating speed of the wind turbine generator.
Since the virtual inertial control can provide a power response to the system quickly in response to changes in the rate of change of frequency, the additional power is designed to:
in the formula:K dis a differential coefficient.
Step 605: when the system frequency is recovered, willPGradually reducing to 0, and connecting the wind generating set to recover the rotating speed.
In summary, a doubly-fed wind turbine frequency control scheme based on rotor kinetic energy control as shown in fig. 7 may be adopted for the wind turbine.
The frequency control system mainly comprises a frequency control module, a rotating speed protection system module and a rotating speed recovery starting module.
A frequency control module: the module is used for transmitting a power signal with frequency regulation, and after obtaining a frequency deviation signal, obtaining a constant additional power Δ according to the formula (7) by obtaining the maximum frequency deviationP。
The rotating speed recovery starting module: the module is used for enabling the rotating speed to be quickly recovered to the optimal operation state; after the constant additional power control is introduced, the doubly-fed wind turbine generator operates at a lower rotating speed (relative optimal rotating speed) after releasing the kinetic energy of the rotor, deviates from the maximum power tracking point, and in order to improve the wind energy utilization rate, the rotating speed still needs to be recovered after the system frequency is recovered to be stable, so that the doubly-fed wind turbine generator returns to the maximum power tracking point again.
The rotating speed protection system module: the module has the function of avoiding the influence on the safe and stable operation of the double-fed wind turbine generator system caused by the excessively low rotor speed reduction when the double-fed wind turbine generator system participates in system frequency modulation; when the rotor speed is lower than the minimum valueω minAnd when the system is started, the rotating speed protection system is started, so that the wind turbine generator does not participate in system frequency control any more.
The low-pass filter is used for eliminating the interference of frequency measurement noise.
Claims (7)
1. The method for controlling the frequency stability of the multi-terminal flexible direct-current power transmission system with wind power participating in frequency modulation is characterized by comprising the following steps of: the method comprises the following steps:
step 1: determining a direct current transmission system structure accessed by wind power:
the method comprises the following steps that a wind power field WF of a wind turbine generator is connected with a sending end converter station VSC1, a receiving end alternating current grid AC1 is connected with a receiving end converter station VSC2, a receiving end alternating current grid AC2 is connected with a receiving end converter station VSC3, and the sending end converter station VSC1, the receiving end converter station VSC2 and the receiving end converter station VSC3 are connected with one another;
step 2: determining the control mode of the receiving end converter station VSC2 and the VSC3 as a direct-current voltage droop control method;
and step 3: introducing power increment related to the grid frequency at the receiving end converter VSC2 and the VSC 3;
and 4, step 4: determining a control mode of the VSC1 of the sending end converter station;
and 5: additional frequency control is introduced at the sending end converter station VSC 1:
step 6: the wind turbine generator set adjusts the rotating speed of the fan according to the frequency change delta f of the VSC1 of the sending end converter station, and outputs active power to support the power of the sending end system.
2. The method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with the wind power participating in the frequency modulation according to claim 1, wherein the method comprises the following steps: step 6 is specifically decomposed into the following steps:
step 601: the kinetic energy stored in the rotor of the wind turbine can be expressed as
In the formula:Jthe rotational inertia of the impeller and the generator;ωthe rotating speed of the rotor of the wind turbine generator set;
step 602: calculating kinetic energy absorbed or released by the wind turbine generator when the frequency of the power grid changes;
when the grid frequency is fromf 0Change tof 1At the same time, the rotorThe rotating speed will be correspondingly drivenω 0 Change toω 1 The rotational kinetic energy absorbed or released by the wind turbine generator is as follows:
step 603: converting kinetic energy stored by the rotating part of the wind turbine generator into frequency modulation power under frequency modulation time by using formula (5), as shown in formula (6):
in the formula:ηconversion efficiency for converting kinetic energy into electric energy;
∆P 1a compensation power responsive to the inertia;
∆tis the inertia response duration;
the active power output of the unit can be only temporarily increased or reduced through the conversion of the kinetic energy of the rotor, and because the speed of the rotor of the unit is limited, the duration of the inertia response of the unit is strictly limited in order to avoid triggering the fault of the unit, and the duration is generally set to 10 s;
the kinetic energy release control process of the rotor of the wind turbine generator set is divided into a power supporting stage and a rotating speed recovery stage; when the frequency of a power grid is reduced, the wind turbine generator set provides active power support by increasing electromagnetic torque, in the process, the rotating speed is rapidly reduced, when the rotating speed is reduced to a lower limit value, the fan quits frequency modulation, at the moment, larger deviation of the frequency is caused, and when the frequency is more serious, secondary falling of the system frequency is caused; the rotating speed recovery process is carried out when the system frequency is not recovered to be stable, so that the reduction of the active power output by the wind turbine generator and the increase of the system load caused by the rotating speed recovery cause a 'superposition effect' on the reduction of the system frequency, the deviation of the system frequency is increased, and the frequency response characteristic is poor; therefore, in order to solve the adverse effect of the rotation speed recovery on the frequency response of the system, the recovery of the rotation speed can be delayed by introducing constant power, and the stability of the system frequency is improved;
double-fed wind turbine generator systemThe power-speed relationship of (a) is shown in fig. 6, wherein,P Mrepresenting the mechanical power delivered by the wind turbine to the doubly fed induction generator,P MPPTrepresenting an active power reference value under the MPPT algorithm;
step 604: when the rotor speed is lower than the minimum valueω min（ω minGenerally taking the value as 0.7 pu), entering a rotating speed recovery process, and delaying the rotating speed recovery of the wind turbine generator by additional power;
since the virtual inertial control can provide a power response to the system quickly in response to changes in the rate of change of frequency, the additional power is designed to:
in the formula:K dis a differential coefficient;
step 605: when the system frequency is recovered, willPGradually reducing to 0, and connecting a wind turbine generator set to recover the rotating speed;
in summary, a doubly-fed wind turbine frequency control scheme based on rotor kinetic energy control as shown in fig. 7 may be adopted for the wind turbine; the frequency control system mainly comprises a frequency control module, a rotating speed protection system module and a rotating speed recovery starting module; a frequency control module: the module is used for transmitting a frequency-adjusted power signal; after obtaining the frequency deviation signal, obtaining the maximum frequency deviation and then obtaining the constant additional power according to the formula (7)P(ii) a The low-pass filter is used for eliminating the interference of frequency measurement noise;
the rotating speed recovery starting module: the module is used for enabling the rotating speed to be quickly recovered to the optimal operation state; after constant additional power control is introduced, the doubly-fed wind turbine generator operates at a lower rotating speed (relative optimal rotating speed) after releasing the kinetic energy of a rotor, and deviates from a maximum power tracking point; in order to improve the wind energy utilization rate, after the system frequency is recovered to be stable, the rotating speed still needs to be recovered, so that the double-fed wind turbine generator set returns to the maximum power tracking point again;
the rotating speed protection system module: the module is madeThe method is used for avoiding the influence on the safe and stable operation of the double-fed wind turbine generator system caused by the over-low reduction of the rotor speed when the double-fed wind turbine generator system participates in system frequency modulation; when the rotor speed is lower than the minimum valueω minAnd when the system is started, the rotating speed protection system is started, so that the wind turbine generator does not participate in system frequency control any more.
3. The method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with the wind power participating in the frequency modulation according to claim 1, wherein the method comprises the following steps: the step 2 specifically comprises the following steps:
droop control is combined with power control and voltage control, and an inner loop current reference value i is generated according to a P-V characteristic curvedrefThe calculation formula is shown as formula (1):
in the formula, Udcref、UdcRespectively direct current reference voltage and direct current measurement voltage;
Prefp is an active power reference value and an active power actual value of the current converter respectively;
Kp、Kiproportional coefficient and integral coefficient of PI regulator;
KDis the droop slope;
1/s represents the integral.
4. The method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with the wind power participating in the frequency modulation according to claim 1, wherein the method comprises the following steps: the step 3 specifically comprises the following steps:
adding a power increment delta Pref related to the measured frequency fac of the alternating current network on the basis of a converter active power reference value Pref set by a receiving end converter VSC2 and a VSC3, wherein the calculation mode is shown as a formula (2):
in the formula (f)acrefRated frequency for the AC power grid;
facactually measuring the frequency of the alternating current network;
Kfis a scaling factor for frequency control.
5. The method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with the wind power participating in the frequency modulation according to claim 1, wherein the method comprises the following steps: the step 4 specifically comprises the following steps: when the wind power plant is connected to the flexible direct current transmission system, the control target of the sending end converter station is to provide rated alternating voltage and frequency as a reference power supply of a wind turbine converter, and therefore grid connection of the wind power plant is achieved.
6. The method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with the wind power participating in the frequency modulation according to claim 1, wherein the method comprises the following steps: the step 5 specifically comprises the following steps:
detecting the direct-current side voltage of the VSC1 receiving end converter station of the sending end converter station and according to the difference U of the direct-current side voltage deviating from the rated voltageDCCalculating the frequency deviation, and converting the change of the direct current voltage into the frequency change delta f of the sending end converter station through a control parameter Kv, wherein the calculation mode is shown as formula (3):
(3)
in the formula, Kv is a control parameter and reflects the proportion of the frequency deviation of the sending end converter station to the direct-current voltage deviation;
ΔUDCis the variation value of the direct current voltage.
7. The method for controlling the frequency stability of the multi-terminal flexible direct-current transmission system with the wind power participating in the frequency modulation according to claim 1, wherein the method comprises the following steps: the sending end converter station VSC1, the receiving end converter station VSC2 and the receiving end converter station VSC3 are all flexible direct current converter stations.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911287747.9A CN110912158A (en) | 2019-12-15 | 2019-12-15 | Multi-terminal flexible direct-current power transmission system frequency stability control method with wind power participating in frequency modulation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911287747.9A CN110912158A (en) | 2019-12-15 | 2019-12-15 | Multi-terminal flexible direct-current power transmission system frequency stability control method with wind power participating in frequency modulation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110912158A true CN110912158A (en) | 2020-03-24 |
Family
ID=69825853
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911287747.9A Pending CN110912158A (en) | 2019-12-15 | 2019-12-15 | Multi-terminal flexible direct-current power transmission system frequency stability control method with wind power participating in frequency modulation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110912158A (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111864769A (en) * | 2020-07-29 | 2020-10-30 | 国网山东省电力公司日照供电公司 | Frequency modulation parameter determination method and system considering frequency response characteristics of fan and system |
| CN112086994A (en) * | 2020-09-23 | 2020-12-15 | 国网江苏省电力有限公司电力科学研究院 | Cascade type hybrid direct current system and control method |
| CN112952842A (en) * | 2021-03-11 | 2021-06-11 | 华北电力大学 | Automatic power flow distribution control method and system between alternating current power distribution networks |
| CN113595157A (en) * | 2021-08-03 | 2021-11-02 | 国家电投集团电站运营技术（北京）有限公司 | Coordination control method, device, equipment and storage medium for active power of wind power plant |
| WO2022041366A1 (en) * | 2020-08-26 | 2022-03-03 | 东南大学溧阳研究院 | Multi-terminal flexible direct current transmission system-based power grid frequency modulation method |
| CN114268127A (en) * | 2021-12-09 | 2022-04-01 | 华北电力大学 | Large-scale wind power accessed hybrid direct current power transmission system transmitting end power grid frequency control strategy |
| CN115173439A (en) * | 2022-09-08 | 2022-10-11 | 西安热工研究院有限公司 | Controllable energy storage and thermal power combined frequency modulation system and method |
| CN116073363A (en) * | 2022-11-24 | 2023-05-05 | 中南大学 | Active fault current suppression method for offshore wind power frequency modulation process of soft direct grid-connected system |
| CN116111616A (en) * | 2023-04-13 | 2023-05-12 | 清华大学 | Multi-time space scale power system frequency full-track coordination optimization control method |
| CN116845927A (en) * | 2023-08-31 | 2023-10-03 | 国网湖北省电力有限公司电力科学研究院 | Control method and device for relieving frequency secondary drop of wind power through soft direct grid-connected system |
| CN117239817A (en) * | 2023-09-20 | 2023-12-15 | 兰州理工大学 | Light storage and wind-solar coordination operation method based on flexible direct current grid connection |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106532746A (en) * | 2016-12-27 | 2017-03-22 | 北京四方继保自动化股份有限公司 | Control system for participation of wind power plant in primary frequency modulation and implementation method |
| CN110188915A (en) * | 2019-04-10 | 2019-08-30 | 国网浙江省电力有限公司电力科学研究院 | Energy-storage system Optimal Configuration Method and system in virtual plant based on scene collection |
| CN110336305A (en) * | 2019-07-22 | 2019-10-15 | 华北电力大学（保定） | A kind of suitable double-fed fan motor unit participates in the improvement additional frequency control method of system frequency adjusting under short trouble |
-
2019
- 2019-12-15 CN CN201911287747.9A patent/CN110912158A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106532746A (en) * | 2016-12-27 | 2017-03-22 | 北京四方继保自动化股份有限公司 | Control system for participation of wind power plant in primary frequency modulation and implementation method |
| CN110188915A (en) * | 2019-04-10 | 2019-08-30 | 国网浙江省电力有限公司电力科学研究院 | Energy-storage system Optimal Configuration Method and system in virtual plant based on scene collection |
| CN110336305A (en) * | 2019-07-22 | 2019-10-15 | 华北电力大学（保定） | A kind of suitable double-fed fan motor unit participates in the improvement additional frequency control method of system frequency adjusting under short trouble |
Non-Patent Citations (3)
| Title |
|---|
| 刘彬彬 等: "基于转子动能控制的双馈风电机组频率控制改进方案", 《电力系统自动化》 * |
| 杨金刚 等: "经柔性直流输电并网的大型风电场频率控制策略", 《电力自动化设备》 * |
| 王瑞明 等: "风电场一次调频分层协调控制研究与应用", 《电力系统保护与控制》 * |
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111864769A (en) * | 2020-07-29 | 2020-10-30 | 国网山东省电力公司日照供电公司 | Frequency modulation parameter determination method and system considering frequency response characteristics of fan and system |
| WO2022041366A1 (en) * | 2020-08-26 | 2022-03-03 | 东南大学溧阳研究院 | Multi-terminal flexible direct current transmission system-based power grid frequency modulation method |
| CN112086994A (en) * | 2020-09-23 | 2020-12-15 | 国网江苏省电力有限公司电力科学研究院 | Cascade type hybrid direct current system and control method |
| CN112952842A (en) * | 2021-03-11 | 2021-06-11 | 华北电力大学 | Automatic power flow distribution control method and system between alternating current power distribution networks |
| CN112952842B (en) * | 2021-03-11 | 2022-09-23 | 华北电力大学 | Automatic power flow distribution control method and system between alternating current power distribution networks |
| CN113595157A (en) * | 2021-08-03 | 2021-11-02 | 国家电投集团电站运营技术（北京）有限公司 | Coordination control method, device, equipment and storage medium for active power of wind power plant |
| CN114268127A (en) * | 2021-12-09 | 2022-04-01 | 华北电力大学 | Large-scale wind power accessed hybrid direct current power transmission system transmitting end power grid frequency control strategy |
| CN115173439A (en) * | 2022-09-08 | 2022-10-11 | 西安热工研究院有限公司 | Controllable energy storage and thermal power combined frequency modulation system and method |
| CN116073363A (en) * | 2022-11-24 | 2023-05-05 | 中南大学 | Active fault current suppression method for offshore wind power frequency modulation process of soft direct grid-connected system |
| CN116073363B (en) * | 2022-11-24 | 2024-05-10 | 中南大学 | Active fault current suppression method for offshore wind power frequency modulation process of soft direct grid-connected system |
| CN116111616A (en) * | 2023-04-13 | 2023-05-12 | 清华大学 | Multi-time space scale power system frequency full-track coordination optimization control method |
| CN116111616B (en) * | 2023-04-13 | 2023-06-16 | 清华大学 | Multi-time space scale power system frequency full-track coordination optimization control method |
| CN116845927A (en) * | 2023-08-31 | 2023-10-03 | 国网湖北省电力有限公司电力科学研究院 | Control method and device for relieving frequency secondary drop of wind power through soft direct grid-connected system |
| CN116845927B (en) * | 2023-08-31 | 2023-11-14 | 国网湖北省电力有限公司电力科学研究院 | Control method and device for relieving frequency secondary drop of wind power through soft direct grid-connected system |
| CN117239817A (en) * | 2023-09-20 | 2023-12-15 | 兰州理工大学 | Light storage and wind-solar coordination operation method based on flexible direct current grid connection |
| CN117239817B (en) * | 2023-09-20 | 2024-05-03 | 兰州理工大学 | Light storage and wind-solar coordination operation method based on flexible direct current grid connection |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110912158A (en) | Multi-terminal flexible direct-current power transmission system frequency stability control method with wind power participating in frequency modulation | |
| CN109066770B (en) | Control method and device for accessing wind power to flexible direct current power transmission system | |
| US20220316443A1 (en) | Fast Frequency Support from Wind Turbine Systems | |
| CN103825293B (en) | A kind of cooperative control method improving the wind energy turbine set-flexible direct current power transmission system of electric power system inertia levels | |
| CN107453410B (en) | Load disturbance double-fed fan participated wind-diesel micro-grid frequency modulation control method | |
| CN105515022A (en) | Virtual double-fed induction generator inertia control method coordinated with secondary frequency regulation | |
| CN105140938B (en) | Double-fed asynchronous Wind turbines booting-self controller method based on energy-storage system | |
| CN111711203B (en) | Two-stage coordination control method and system for offshore wind farm participating in frequency modulation | |
| CN105790297A (en) | Internal potential response-based inertia control method and device for full-power wind generator | |
| CN107546772A (en) | Electric voltage frequency control method for coordinating of the double-fed asynchronous Wind turbines in micro-capacitance sensor | |
| CN110323763B (en) | Inverter frequency modulation method integrating rotation inertia simulation and primary frequency modulation control | |
| CN116845924B (en) | Grid-structured wind power plant voltage source control method based on phase angle self-generation strategy | |
| CN111525599B (en) | Frequency modulation control method for speed-increasing type wind turbine generator | |
| CN109659961A (en) | A kind of dynamic power system LOAD FREQUENCY coordination approach based on frequency dividing control | |
| CN115498656A (en) | Virtual synchronous wind power plant cooperative photovoltaic power station additional damping control method and device | |
| CN113193587B (en) | Sending-out cooperative control method and system for island double-fed wind power plant through high-voltage direct-current transmission | |
| Liu et al. | The effects of wind turbine and energy storage participating in frequency regulation on system frequency response | |
| Chu et al. | Coordinated control strategy for improving frequency stability of offshore wind farms connected to the grid through MMC-HVDC transmission | |
| CN111092438B (en) | Primary frequency modulation method and device for wind turbine generator | |
| CN114069729B (en) | Permanent magnet direct-driven wind farm reactive voltage control strategy based on self-adaptive droop control | |
| CN113852099B (en) | Rapid frequency response control system and method for direct-driven wind turbine generator | |
| Ranjan et al. | A Novel Control Approach for Grid-Integrated DFIG Driven Wind Energy Systems | |
| CN112909998B (en) | Transient and steady state power uniform control method for diesel generator set-inverter parallel power supply system | |
| CN111193274B (en) | Inertia response control method and device for high-voltage direct-current power transmission system | |
| CN114421498A (en) | Medium-voltage wind power system fluctuation power stabilizing method and system based on energy router |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200324 |
|
| RJ01 | Rejection of invention patent application after publication |