CN113381419B - Full-power converter fault ride-through reactive power control method, system, medium and equipment - Google Patents
Full-power converter fault ride-through reactive power control method, system, medium and equipment Download PDFInfo
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- CN113381419B CN113381419B CN202110705737.3A CN202110705737A CN113381419B CN 113381419 B CN113381419 B CN 113381419B CN 202110705737 A CN202110705737 A CN 202110705737A CN 113381419 B CN113381419 B CN 113381419B
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- 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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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- 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
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
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- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- 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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
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- 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
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Abstract
The invention discloses a fault ride-through reactive power control method, a system, a medium and equipment for a full-power converter, which mainly aim at a large-scale half-direct-drive permanent magnet synchronous wind turbine generator system connected with the full-power converter in a grid, can adopt a control mode of changing a reactive support coefficient under the fault operation state of the wind turbine generator system, change the value of the reactive support coefficient in real time according to different fault voltage drop or swell degrees, quickly inject reactive current into a power grid to support the voltage of the power grid, realize the flexible fault voltage ride-through of the generator system, and improve the grid connection reliability of the wind turbine generator system.
Description
Technical Field
The invention relates to the technical field of wind turbine generator system fault voltage ride through, in particular to a wind turbine generator system full-power converter fault ride through reactive current control method, a system, a storage medium and computing equipment.
Background
According to the requirements of the existing fault ride-through test regulations, the wind turbine generator sets should inject reactive current into the power grid preferentially under the working condition of power grid faults to support the voltage recovery of the power grid. However, in the actual control of the current full-power converter, the reactive support coefficient given by the reactive current is fixed, and the situation of insufficient reactive power may occur in the reactive power dispatching process of the wind power plant, so that the problem is urgently needed to be solved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for controlling the fault ride-through reactive current of a full-power converter of a wind turbine generator, which can adjust the reactive current injection speed in real time according to different voltage drop or sudden rise depths of grid-connected points, can inject the reactive current into a power grid preferentially and rapidly under the fault working condition to support the voltage recovery of the power grid and realize the fault voltage ride-through of the wind turbine generator.
The invention also provides a control system for the fault ride-through reactive current of the full-power converter of the wind turbine generator.
A third object of the present invention is to provide a storage medium.
It is a fourth object of the invention to provide a computing device.
The first purpose of the invention is realized by the following technical scheme: a method for controlling fault ride-through reactive current of a full-power converter of a wind turbine generator system adopts a control mode of changing a reactive support coefficient, changes the value of the reactive support coefficient in real time according to different fault voltage drop or swell degrees, and preferentially and quickly injects reactive current into a power grid to support voltage recovery of the power grid, so that grid connection reliability of the wind turbine generator system is improved.
Further, the method for controlling the fault ride-through reactive current of the full-power converter of the wind turbine generator set comprises the following steps:
1) data acquisition
A controller of the full-power converter collects an effective value and an instantaneous value of three-phase voltage of a grid-connected point; a grid-side inverter of the full-power converter feeds back a three-phase current effective value and a three-phase current instantaneous value of a grid-connected point; the full-power converter adopts a decoupling double-synchronous coordinate system phase-locked loop (DDSRF-PLL) to extract real-time positive sequence voltage, and refreshes internal data according to a control and communication period;
2) decision logic for ingress and egress fault ride-through modes of operation
A controller of the full-power converter detects a positive sequence voltage value of a grid-connected point in real time, and determines whether to enter a fault ride-through operation mode or a steady-state operation mode according to the magnitude of the positive sequence voltage value; the fault ride-through operation mode comprises a low-voltage ride-through operation mode and a high-voltage ride-through operation mode, and in the fault ride-through operation mode, corresponding reactive current is injected into the power grid according to the positive sequence voltage value of the grid-connected point to support the voltage recovery of the power grid; the steady-state operation mode is that the wind turbine generator enters a unit power factor grid-connected operation state from a fault voltage ride-through state;
3) steady state mode of operation
After the wind turbine generator successfully finishes the fault voltage ride-through state, the full-power converter is restored to the unit power factor operation state, and the grid-side inverter of the full-power converter controls the voltage state of the grid-connected point.
Further, in the step 2), a controller of the full-power converter detects a positive sequence voltage value of a grid-connected point in real time; when the positive sequence voltage value is less than U a When the full-power converter enters a low-voltage ride-through operation mode; when the positive sequence voltage value is larger than U b When the full-power converter enters a high-voltage ride-through operation mode; when the positive sequence voltage value is greater than or equal to U c Or less than or equal to U d When the wind turbine generator system is in a grid-connected operation state with unit power factor from a fault voltage ride-through state, namely a steady-state operation mode; wherein, U a To go into the low voltage ride-through threshold, U b To go into the high voltage ride-through threshold, U c Exit from the low voltage ride through threshold, U d To exit the high voltage crossing threshold.
Further, in step 2), when the wind turbine generator enters the fault ride-through operation mode, the current operation mode is determined, including:
a. in the low voltage ride through mode of operation, according to [ (U) T +U 1 -1)*(K 2 -K 1 )/(U 1 -U 2 )+K 1 ]*(U T -U 3 )*I n Calculating to obtain a capacitive reactive current reference value I r1 (ii) a During the low voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r1 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 1 To go into the low voltage ride-through threshold, U 2 Minimum voltage value of reactive current, U 3 To exit the low voltage ride through threshold;
b. in the high voltage ride through mode of operation, according to [ (U) T -U 4 )*(K 4 -K 3 )/(U 5 -U 4 )+K 3 ]*(U T -U 6 )*I n Calculating to obtain the reference value I of the inductive reactive current r2 (ii) a During the high voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r2 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 4 To go into the high voltage ride-through threshold, U 5 For generating maximum voltage value of reactive current, U 6 To exit the high voltage ride through threshold;
the above U T Is the positive sequence voltage value of the grid-connected point; i is n Rated current of the full-power converter; k 1 、K 2 、K 3 、K 4 All are reactive support coefficients; the allowed current I is less than or equal to the maximum allowed current I in short time during fault due to capacity limitation of the full-power converter max (ii) a When the wind turbine generator is in a fault ride-through operation mode, on the basis of ensuring reactive power priority, a reactive current reference value I of the wind turbine generator is in a low-voltage ride-through period r1 ＝max(I r1 -ΔI r ，-I max ) (ii) a Reactive current reference value I of high voltage ride through period r2 ＝min(I r2 +ΔI r ，I max ) (ii) a Wherein, Delta I r The step size is limited during fault ride-through.
The second purpose of the invention is realized by the following technical scheme: a wind turbine generator full-power converter fault ride-through reactive current control system adopts a control mode of changing a reactive support coefficient, changes the value of the reactive support coefficient in real time according to different fault voltage drop or swell degrees, and preferentially and quickly injects reactive current into a power grid to support the voltage recovery of the power grid, so that the grid-connected reliability of the wind turbine generator is improved; the fault ride-through system comprises a data acquisition module, a fault ride-through operation mode judgment module and a steady-state operation mode control module;
the data acquisition module acquires the three-phase voltage effective value and the three-phase voltage instantaneous value of the grid-connected point through a controller of the full-power converter; feeding back a three-phase current effective value and a three-phase current instantaneous value of a grid-connected point through a grid-side inverter of the full-power converter; adopting a decoupling double synchronous coordinate system phase-locked loop (DDSRF-PLL) to extract real-time positive sequence voltage, and refreshing internal data of the controller according to a control and communication period;
the fault ride-through operation mode judgment module detects a positive sequence voltage value of a grid-connected point in real time through a controller of the full-power converter and determines whether to enter a fault ride-through operation mode or a steady-state operation mode according to the magnitude of the positive sequence voltage value; the fault ride-through operation mode comprises a low-voltage ride-through operation mode and a high-voltage ride-through operation mode, and in the fault ride-through operation mode, corresponding reactive current is injected into the power grid according to the positive sequence voltage value of the grid-connected point to support the voltage recovery of the power grid;
the steady-state operation mode control module enables the wind turbine generator to enter a unit power factor grid-connected operation state from a fault voltage ride-through state, namely, after the wind turbine generator successfully completes the fault voltage ride-through state, the full-power converter recovers to the unit power factor operation state, and at the moment, the grid-side inverter of the full-power converter controls the grid-connected point voltage state.
Further, the fault ride-through operation mode determination module specifically executes the following operations:
detecting a positive sequence voltage value of a grid-connected point in real time through a controller of the full-power converter; when the positive sequence voltage value is less than U a When the full-power converter enters a low-voltage ride-through operation mode; when the positive sequence voltage value is larger than U b When the full-power converter enters a high-voltage ride-through operation mode; when the positive sequence voltage value is greater than or equal to U c Or less than or equal to U d When the wind turbine generator system is in a grid-connected operation state with unit power factor from a fault voltage ride-through state, namely a steady-state operation mode; wherein, U a To go into the low voltage ride-through threshold, U b To go into the high voltage ride-through threshold, U c Exit from the low voltage ride through threshold, U d To exit the high voltage ride through threshold;
when the wind turbine generator enters a fault ride-through operation mode, a current operation mode is judged, and the following steps are included:
a. in the low voltage ride through mode of operation, according to [ (U) T +U 1 -1)*(K 2 -K 1 )/(U 1 -U 2 )+K 1 ]*(U T -U 3 )*I n Calculating to obtain a capacitive reactive current reference value I r1 (ii) a During the low voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r1 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 1 To go into the low voltage ride-through threshold, U 2 For generating a minimum voltage value of reactive current, U 3 To exit the low voltage ride through threshold;
b. in the high voltage ride through mode of operation, according to [ (U) T -U 4 )*(K 4 -K 3 )/(U 5 -U 4 )+K 3 ]*(U T -U 6 )*I n Calculating to obtain the reference value I of the inductive reactive current r2 (ii) a During the high voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r2 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 4 To go into the high voltage ride-through threshold, U 5 For generating maximum voltage value of reactive current, U 6 To exit the high voltage ride through threshold;
the U is T Is the positive sequence voltage value of the grid-connected point; i is n Rated current of the full-power converter; k 1 、K 2 、K 3 、K 4 All are reactive support coefficients; the allowed current I is less than or equal to the maximum allowed current I in short time during fault due to capacity limitation of the full-power converter max (ii) a When the wind turbine generator is in a fault ride-through operation mode, on the basis of ensuring reactive power priority, a reactive current reference value I of the wind turbine generator is in a low-voltage ride-through period r1 ＝max(I r1 -ΔI r ，-I max ) (ii) a Reactive current reference value I of high voltage ride through period r2 ＝min(I r2 +ΔI r ，I max ) (ii) a Wherein, Delta I r The step size is limited during fault ride-through.
The third purpose of the invention is realized by the following technical scheme: a storage medium stores a program, and when the program is executed by a processor, the method for controlling the fault ride-through reactive current of the full-power converter of the wind turbine generator set is realized.
The fourth purpose of the invention is realized by the following technical scheme: the computing device comprises a processor and a memory for storing an executable program of the processor, and when the processor executes the program stored in the memory, the method for controlling the fault ride-through reactive current of the full-power converter of the wind turbine generator set is realized.
Compared with the prior art, the invention has the following advantages and beneficial effects:
according to the method, under the fault operation state of the wind turbine generator, a control mode of changing the reactive support coefficient is adopted, the value of the reactive support coefficient is changed in real time according to different fault voltage drop or swell degrees, the reactive current is rapidly injected into the power grid to support the voltage of the power grid, the flexible fault voltage ride-through of the wind turbine generator can be realized, and the grid connection reliability of the wind turbine generator is improved.
Drawings
Fig. 1 is an architecture diagram of a wind turbine generator in the embodiment.
FIG. 2 is a control flow diagram of the method of the present invention.
Fig. 3 is a schematic diagram of a DDSRF-PLL.
Fig. 4 is a reactive current graph.
Fig. 5 is an architecture diagram of the system of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Example 1
The embodiment discloses a method for controlling the fault ride-through reactive current of a full-power converter of a wind turbine generator, which is shown in figure 1 and mainly aims at a large semi-direct-drive permanent magnet synchronous wind turbine generator (the main components of which comprise a gear box, a medium-speed permanent magnet synchronous generator, an impeller, a tower, a main control system, a variable pitch system, a full-power converter, a step-up transformer and the like) which is connected with a full-power converter in a grid, wherein the use condition is that when the wind turbine generator carries out fault voltage ride-through, a control mode of changing the reactive support coefficient is adopted, the value of the reactive support coefficient is changed in real time according to different fault voltage drop or swell degrees, and the reactive current is preferentially and quickly injected into a power grid to support the voltage recovery of the power grid, so that the grid connection reliability of the wind turbine generator is improved. As shown in fig. 2, the method comprises the following steps:
1) data acquisition
A controller of the full-power converter collects an effective value and an instantaneous value of three-phase voltage of a grid-connected point; a grid-side inverter of the full-power converter feeds back a three-phase current effective value and a three-phase current instantaneous value of a grid-connected point; the full-power converter adopts a decoupling double synchronous coordinate system phase-locked loop (DDSRF-PLL) to extract real-time positive sequence voltage, the basic principle of the full-power converter is shown in figure 3, and internal data are refreshed according to a control and communication period.
2) Decision logic for ingress and egress fault ride-through modes of operation
Detecting a positive sequence voltage value of a grid-connected point in real time by a controller of the full-power converter; when the positive sequence voltage value is less than U a When the full-power converter enters a low-voltage ride-through operation mode; when the positive sequence voltage value is larger than U b When the full-power converter enters a high-voltage ride-through operation mode; when the positive sequence voltage value is greater than or equal to U c Or less than or equal to U d When the wind turbine generator system is in a grid-connected operation state with unit power factor from a fault voltage ride-through state, namely a steady-state operation mode; wherein, U a To enter the low voltage ride through threshold, 0.85 p.u.u.is recommended b To enter the high voltage ride-through threshold, 1.15 p.u.u.is recommended c The low voltage crossing threshold is exited, and 0.9p.u, U is recommended d To exit the high voltage crossing threshold, 1.1p.u is recommended.
When the wind turbine generator enters a fault ride-through operation mode, a current operation mode is judged, and the following steps are included:
a. in the low voltage ride through mode of operation, according to [ (U) T +U 1 -1)*(K 2 -K 1 )/(U 1 -U 2 )+K 1 ]*(U T -U 3 )*I n Calculate to obtain itCapacitive reactive current reference value I r1 (ii) a During the low voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r1 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 1 To enter the low voltage ride through threshold, the recommended value is 0.85 p.u; u shape 2 The recommended value is 0.2p.u for the lowest voltage value of reactive current; u shape 3 In order to exit the low voltage ride through threshold, the recommended value is 0.9 p.u; voltage is U 1 Time, reactive support coefficient K 1 2 is recommended; voltage is U 2 Time, reactive support coefficient K 2 And 8 is recommended.
b. In the high voltage ride through mode of operation, according to [ (U) T -U 4 )*(K 4 -K 3 )/(U 5 -U 4 )+K 3 ]*(U T -U 6 )*I n Calculating to obtain the reference value I of the inductive reactive current r2 (ii) a During the high voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r2 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 4 To enter the high voltage ride-through threshold, a recommended value of 1.15 p.u. 5 The recommended value for generating the maximum voltage value of the reactive current is 1.3 p.u.U 6 In order to exit the high voltage ride through threshold, the recommended value is 1.1 p.u; voltage is U 4 Time, reactive support coefficient K 3 2 is recommended; voltage is U 5 Time, reactive support coefficient K 4 The recommendation is to take 5.
The U is T Is the positive sequence voltage value of the grid-connected point; i is n Rated current of the full-power converter; the allowed current I is less than or equal to the maximum allowed current I in short time during fault due to capacity limitation of the full-power converter max ，I max Recommend 1.5I n (ii) a When the wind turbine generator is in a fault ride-through operation mode, on the basis of ensuring reactive power priority, a reactive current reference value I of the wind turbine generator is in a low-voltage ride-through period r1 ＝max(I r1 -ΔI r ，-I max ) (ii) a Reactive current reference value I of high voltage ride through period r2 ＝min(I r2 +ΔI r ，I max ) (ii) a Wherein, Delta I r For limiting the step size during fault crossing, the recommended value is 300 p.u/s.
The reactive current curve is shown in FIG. 4, where I q1 For fault voltage of U 1 Current value of time, I q2 For fault voltage of U 2 Current value of time, I q4 For fault voltage of U 4 Current value of time, I q5 For fault voltage of U 5 The value of the reactive current at time.
3) Steady state mode of operation
After the wind turbine generator successfully finishes the fault voltage ride-through state, the full-power converter is restored to the unit power factor operation state, and the grid-side inverter of the full-power converter controls the voltage state of the grid-connected point.
Example 2
The embodiment discloses a fault ride-through reactive current control system for a full-power converter of a wind turbine generator, which adopts a control mode of changing a reactive support coefficient, changes the value of the reactive support coefficient in real time according to different fault voltage drop or swell degrees, and preferentially and quickly injects reactive current into a power grid to support the voltage recovery of the power grid, so that the grid-connected reliability of the wind turbine generator is improved. As shown in fig. 5, the system includes a data acquisition module, a fault ride-through operation mode determination module, and a steady-state operation mode control module.
The data acquisition module acquires the three-phase voltage effective value and the three-phase voltage instantaneous value of a grid connection point through a controller of the full-power converter; feeding back a three-phase current effective value and a three-phase current instantaneous value of a grid-connected point through a grid-side inverter of a full-power converter; adopting a decoupling double synchronous coordinate system phase-locked loop (DDSRF-PLL) to extract real-time positive sequence voltage, and refreshing internal data of the controller according to a control and communication period;
the fault ride-through operation mode judgment module detects a positive sequence voltage value of a grid-connected point in real time through a controller of the full-power converter, and determines whether to enter a fault ride-through operation mode or a steady-state operation mode according to the magnitude of the positive sequence voltage value; the fault ride-through operation mode comprises a low-voltage ride-through operation mode and a high-voltage ride-through operation mode, and in the fault ride-through operation mode, corresponding reactive current is injected into the power grid according to the positive sequence voltage value of the grid-connected point to support the voltage recovery of the power grid;
the steady-state operation mode control module enables the wind turbine generator to enter a unit power factor grid-connected operation state from a fault voltage ride-through state, namely after the wind turbine generator successfully completes the fault voltage ride-through state, the full-power converter restores to the unit power factor operation state, and at the moment, the grid-side inverter of the full-power converter controls the grid-connected point voltage state.
The fault ride-through operation mode judgment module specifically executes the following operations:
detecting a positive sequence voltage value of a grid-connected point in real time through a controller of the full-power converter; when the positive sequence voltage value is less than U a When the full-power converter enters a low-voltage ride-through operation mode; when the positive sequence voltage value is larger than U b When the full-power converter enters a high-voltage ride-through operation mode; when the positive sequence voltage value is greater than or equal to U c Or less than or equal to U d When the wind turbine generator system is in a grid-connected operation state with unit power factor from a fault voltage ride-through state, namely a steady-state operation mode; wherein, U a To enter the low voltage ride through threshold, 0.85 p.u.u.is recommended b To enter the high voltage ride-through threshold, 1.15 p.u.u.is recommended c The low voltage crossing threshold is exited, and 0.9p.u, U is recommended d In order to quit the high voltage crossing threshold, 1.1p.u is recommended;
when the wind turbine generator enters a fault ride-through operation mode, a current operation mode is judged, and the following steps are included:
a. in the low voltage ride through mode of operation, according to [ (U) T +U 1 -1)*(K 2 -K 1 )/(U 1 -U 2 )+K 1 ]*(U T -U 3 )*I n Calculating to obtain a capacitive reactive current reference value I r1 (ii) a During the low voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r1 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 1 To enter the low voltage ride through threshold, the recommended value is 0.85 p.u; u shape 2 The recommended value is 0.2p.u for the lowest voltage value of reactive current; u shape 3 In order to exit the low voltage ride through threshold, the recommended value is 0.9 p.u; voltage is U 1 Time, reactive support coefficient K 1 2 is recommended; voltage is U 2 Time, reactive support coefficient K 2 Recommending and taking 8;
b. in the high voltage ride through mode of operation, according to [ (U) T -U 4 )*(K 4 -K 3 )/(U 5 -U 4 )+K 3 ]*(U T -U 6 )*I n Calculating to obtain the reference value I of the inductive reactive current r2 (ii) a During the high voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive ＝I r2 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 4 To enter the high voltage ride-through threshold, a recommended value of 1.15 p.u. 5 The recommended value for generating the maximum voltage value of the reactive current is 1.3 p.u.U 6 In order to exit the high voltage ride through threshold, the recommended value is 1.1 p.u; voltage is U 4 Time, reactive support coefficient K 3 2 is recommended; voltage is U 5 Time, reactive support coefficient K 4 5 is recommended;
the U is T Is the positive sequence voltage value of the grid-connected point; i is n Rated current of the full-power converter; the allowed current I is less than or equal to the maximum allowed current I in short time during fault due to capacity limitation of the full-power converter max ，I max Recommend 1.5I n (ii) a When the wind turbine generator is in a fault ride-through operation mode, on the basis of ensuring reactive power priority, a reactive current reference value I of the wind turbine generator is in a low-voltage ride-through period r1 ＝max(I r1 -ΔI r ，-I max ) (ii) a Reactive current reference value I of high voltage ride through period r2 ＝min(I r2 +ΔI r ，I max ) (ii) a Wherein, Delta I r For during fault ride-throughAnd limiting the step size, and taking a recommended value of 300 p.u/s.
Example 3
The embodiment discloses a storage medium, which stores a program, and when the program is executed by a processor, the method for controlling the fault ride-through reactive current of the full-power converter of the wind turbine generator system in the embodiment 1 is realized.
The storage medium in this embodiment may be a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a Random Access Memory (RAM), a usb disk, a removable hard disk, or other media.
Example 4
The embodiment discloses a computing device, which comprises a processor and a memory, wherein the memory is used for storing an executable program of the processor, and when the processor executes the program stored in the memory, the method for controlling the fault ride-through reactive current of the full-power converter of the wind turbine generator system in the embodiment 1 is realized.
The computing device in this embodiment may be a desktop computer, a notebook computer, a smart phone, a PDA handheld terminal, a tablet computer, a Programmable Logic Controller (PLC), or other terminal devices with a processor function.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (5)
1. A wind turbine generator full-power converter fault ride-through reactive current control method is characterized in that a control mode of changing a reactive support coefficient is adopted, the value of the reactive support coefficient is changed in real time according to different fault voltage falling or swell degrees, and reactive current is preferentially and quickly injected into a power grid to support the voltage recovery of the power grid, so that the grid-connection reliability of the wind turbine generator is improved, and the method comprises the following steps:
1) data acquisition
A controller of the full-power converter collects an effective value and an instantaneous value of three-phase voltage of a grid-connected point; a grid-side inverter of the full-power converter feeds back a three-phase current effective value and a three-phase current instantaneous value of a grid-connected point; the full-power converter adopts a decoupling double-synchronous coordinate system phase-locked loop DDSRF-PLL to extract real-time positive sequence voltage, and refreshes internal data according to a control and communication period;
2) decision logic for ingress and egress fault ride-through modes of operation
A controller of the full-power converter detects a positive sequence voltage value of a grid-connected point in real time, and determines whether to enter a fault ride-through operation mode or a steady-state operation mode according to the magnitude of the positive sequence voltage value; the fault ride-through operation mode comprises a low-voltage ride-through operation mode and a high-voltage ride-through operation mode, and in the fault ride-through operation mode, corresponding reactive current is injected into the power grid according to the positive sequence voltage value of the grid-connected point to support the voltage recovery of the power grid; the steady-state operation mode is that the wind turbine generator enters a unit power factor grid-connected operation state from a fault voltage ride-through state;
when the wind turbine generator enters a fault ride-through operation mode, a current operation mode is judged, and the following steps are included:
a. in the low voltage ride through mode of operation, according to [ (U) T +U 1 -1）*（K 2 -K 1 ）/(U 1 -U 2 )+ K 1 ]*( U T -U 3 )*I n Calculating to obtain a capacitive reactive current reference value I r1 (ii) a During the low voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive =I r1 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 1 To go into the low voltage ride-through threshold, U 2 For generating a minimum voltage value of reactive current, U 3 To exit the low voltage ride through threshold;
b. in the high voltage ride through mode of operation, according to [ (U) T -U 4 ）*（K 4 -K 3 ）/(U 5 -U 4 )+ K 3 ]*( U T -U 6 )*I n ComputingTo obtain the inductive reactive current reference value I r2 (ii) a During the high voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive =I r2 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 4 To go into the high voltage ride-through threshold, U 5 For generating maximum voltage value of reactive current, U 6 To exit the high voltage ride through threshold;
the above U T Is the positive sequence voltage value of the grid-connected point; i is n Rated current of the full-power converter; k 1 、K 2 、K 3 、 K 4 All are reactive support coefficients; the allowed current I is less than or equal to the maximum allowed current I in short time during fault due to capacity limitation of the full-power converter max (ii) a When the wind turbine generator is in a fault ride-through operation mode, on the basis of ensuring reactive power priority, a reactive current reference value I of the wind turbine generator is in a low-voltage ride-through period r1 =max（I r1 -ΔI r ，-I max ) (ii) a Reactive current reference value I of high voltage ride through period r2 =min（I r2 +ΔI r ，I max ) (ii) a Wherein, Delta I r Limiting step size for fault crossing period;
3) steady state mode of operation
After the wind turbine generator successfully finishes the fault voltage ride-through state, the full-power converter is restored to the unit power factor operation state, and the grid-side inverter of the full-power converter controls the voltage state of the grid-connected point.
2. The method for controlling the fault ride-through reactive current of the full-power converter of the wind turbine generator system according to claim 1, wherein in the step 2), a controller of the full-power converter detects a positive sequence voltage value of a grid-connected point in real time; when the positive sequence voltage value is less than U a When the full-power converter enters a low-voltage ride-through operation mode; when the positive sequence voltage value is larger than U b When the full-power converter enters a high-voltage ride-through operation mode; when the positive sequence voltage value is greater than or equal to U c Or less than or equal to U d When the wind turbine generator system is in a grid-connected operation state with unit power factor from a fault voltage ride-through state, namely a steady-state operation mode; wherein, U a To go into the low voltage ride-through threshold, U b To go into the high voltage ride-through threshold, U c Exit from the low voltage ride through threshold, U d To exit the high voltage crossing threshold.
3. A wind turbine generator full-power converter fault ride-through reactive current control system is characterized in that the system adopts a control mode of changing a reactive support coefficient, changes the value of the reactive support coefficient in real time according to different fault voltage drop or swell degrees, and preferentially and quickly injects reactive current into a power grid to support the voltage recovery of the power grid, so that the grid-connection reliability of the wind turbine generator is improved; the fault ride-through system comprises a data acquisition module, a fault ride-through operation mode judgment module and a steady-state operation mode control module;
the data acquisition module acquires the three-phase voltage effective value and the three-phase voltage instantaneous value of the grid-connected point through a controller of the full-power converter; feeding back a three-phase current effective value and a three-phase current instantaneous value of a grid-connected point through a grid-side inverter of the full-power converter; adopting a decoupling double synchronous coordinate system phase-locked loop DDSRF-PLL to extract real-time positive sequence voltage, and refreshing internal data of a controller according to a control and communication period;
the fault ride-through operation mode judgment module detects a positive sequence voltage value of a grid-connected point in real time through a controller of the full-power converter and determines whether to enter a fault ride-through operation mode or a steady-state operation mode according to the magnitude of the positive sequence voltage value; the fault ride-through operation mode comprises a low-voltage ride-through operation mode and a high-voltage ride-through operation mode, and in the fault ride-through operation mode, corresponding reactive current is injected into the power grid according to the positive sequence voltage value of the grid-connected point to support the voltage recovery of the power grid;
the steady-state operation mode control module enables the wind turbine generator to enter a unit power factor grid-connected operation state from a fault voltage ride-through state, namely, after the wind turbine generator successfully completes the fault voltage ride-through state, the full-power converter recovers to the unit power factor operation state, and at the moment, the grid-side inverter of the full-power converter controls the voltage state of a grid-connected point;
the fault ride-through operation mode judgment module specifically executes the following operations:
detecting a positive sequence voltage value of a grid-connected point in real time through a controller of the full-power converter; when the positive sequence voltage value is less than U a When the full-power converter enters a low-voltage ride-through operation mode; when the positive sequence voltage value is larger than U b When the full-power converter enters a high-voltage ride-through operation mode; when the positive sequence voltage value is greater than or equal to U c Or less than or equal to U d When the wind turbine generator system is in a grid-connected operation state with unit power factor from a fault voltage ride-through state, namely a steady-state operation mode; wherein, U a To go into the low voltage ride-through threshold, U b To go into the high voltage ride-through threshold, U c Exit from the low voltage ride through threshold, U d To exit the high voltage ride through threshold;
when the wind turbine generator enters a fault ride-through operation mode, a current operation mode is judged, and the following steps are included:
a. in the low voltage ride through mode of operation, according to [ (U) T +U 1 -1）*（K 2 -K 1 ）/(U 1 -U 2 )+ K 1 ]*( U T -U 3 )*I n Calculating to obtain a capacitive reactive current reference value I r1 (ii) a During the low voltage ride through period, the full-power converter shields the instruction given by the master control system of the wind turbine generator, and the full-power converter actually sends out a reactive current value I reactive =I r1 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 1 To go into the low voltage ride-through threshold, U 2 For generating a minimum voltage value of reactive current, U 3 To exit the low voltage ride through threshold;
b. in the high voltage ride through mode of operation, according to [ (U) T -U 4 ）*（K 4 -K 3 ）/(U 5 -U 4 )+ K 3 ]*( U T -U 6 )*I n Calculating to obtain the reference value I of the inductive reactive current r2 (ii) a During high voltage ride through, the main control system of the full-power converter shielding wind turbine generator sets providesCommand of (1), the full power converter actually sends out a reactive current value I reactive =I r2 Supporting the voltage of the power grid until the voltage of the grid-connected point is recovered, and then executing a master control instruction; wherein, U 4 To go into the high voltage ride-through threshold, U 5 For generating maximum voltage value of reactive current, U 6 To exit the high voltage ride through threshold;
the U is T Is the positive sequence voltage value of the grid-connected point; i is n Rated current of the full-power converter; k 1 、K 2 、K 3 、 K 4 All are reactive support coefficients; the allowed current I is less than or equal to the maximum allowed current I in short time during fault due to capacity limitation of the full-power converter max (ii) a When the wind turbine generator is in a fault ride-through operation mode, on the basis of ensuring reactive power priority, a reactive current reference value I of the wind turbine generator is in a low-voltage ride-through period r1 =max（I r1 -ΔI r ，-I max ) (ii) a Reactive current reference value I of high voltage ride through period r2 =min（I r2 +ΔI r ，I max ) (ii) a Wherein, Delta I r The step size is limited during fault ride-through.
4. A storage medium storing a program, wherein the program, when executed by a processor, implements the wind turbine full power converter fault ride-through reactive current control method of any of claims 1 or 2.
5. A computing device comprising a processor and a memory for storing a processor executable program, wherein the processor, when executing the program stored in the memory, implements the wind turbine full power converter fault ride-through reactive current control method of any of claims 1 or 2.
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