CN113824146A - Wind turbine transient characteristic improving method based on wind storage integration - Google Patents

Wind turbine transient characteristic improving method based on wind storage integration Download PDF

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CN113824146A
CN113824146A CN202110981102.6A CN202110981102A CN113824146A CN 113824146 A CN113824146 A CN 113824146A CN 202110981102 A CN202110981102 A CN 202110981102A CN 113824146 A CN113824146 A CN 113824146A
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value
current
wind
wind turbine
converter
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秦世耀
应有
李少林
杨靖
法拉蒂尔
孟明
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China Electric Power Research Institute Co Ltd CEPRI
Zhejiang Windey Co Ltd
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China Electric Power Research Institute Co Ltd CEPRI
Zhejiang Windey Co Ltd
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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
    • 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
    • H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
    • 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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics
    • 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
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • 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
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention discloses a wind turbine transient characteristic improving method based on wind storage integration. Aiming at improving the adaptability of the power grid of the wind turbine generator and the quality of electric energy, the invention adopts the following scheme: when detecting that the grid-connected point voltage of the wind turbine generator is in low voltage ride through, switching the wind storage integrated system to a low-ride through mode; when detecting that the grid-connected point voltage of the wind turbine generator is in high voltage ride through, switching the wind storage integrated system to a high-ride-through mode; when no trigger signal exists, the wind storage integrated system is in a power quality mode. The wind storage integrated control system has the advantages that algorithm strategy integration is carried out on a fault ride-through control algorithm and a power quality control algorithm of the energy storage and wind turbine generator based on the wind storage integrated hardware topology, unified coordination of the wind storage integrated control system is achieved, and transient characteristics of the wind turbine generator are improved.

Description

Wind turbine transient characteristic improving method based on wind storage integration
Technical Field
The invention relates to the technical field of safety analysis of a power system, in particular to a wind turbine transient characteristic improving method based on wind storage integration.
Background
Changing the energy structure and improving the proportion of clean energy such as wind energy in the energy is an important strategic measure for realizing 'carbon peak reaching and carbon neutralization'. With the increase of the wind power grid-connected capacity, the electric power system is changed from a strong power grid to a weak power grid, the problem of electric energy quality is increasingly prominent, and the electric power quality is mainly embodied in the following three aspects: the randomness and the intermittence of wind resources enable the wind power grid-connected power to have a large amount of fluctuation, and a harmonic source is formed; the wind turbine generator system controls the power of the power grid through power electronic elements, and the nonlinear volt-ampere characteristics of the power electronic elements enable the power electronic elements to inject a large amount of higher harmonics into a power system; the non-sinusoidal distribution of the magnetomotive force of the doubly-fed generator enables the doubly-fed generator to generate harmonic electromotive force while generating fundamental electromotive force. On the other hand, the change of the power grid structure of the traditional power system also puts higher requirements on transient characteristics such as fault ride-through of the wind turbine generator and the like.
Currently, much research is carried out on the aspect of improving the quality of wind power grid-connected electric energy, and the research can be mainly summarized into the following two types: install a Unified Power Quality Conditioner (UPQC) or utilize energy storage technology.
Aiming at the transient problem existing after the wind turbine generator is connected to the grid, partial scholars add a centralized energy storage device at the power supply side, utilize energy storage to carry out output stabilization, and utilize energy storage converter resources to carry out harmonic wave and unbalance compensation so as to improve the quality problem of electric energy generated during the wind turbine grid connection, and meanwhile, the centralized energy storage is also used as an important means of frequency modulation of a power system to enhance the frequency stability of the system; and some students connect the energy storage system into the wind turbine generator, develop a unified coordination controller for frequency modulation and fault ride-through, and coordinate active balance and reactive support by utilizing the energy storage device to meet the requirements of low voltage ride-through, high voltage ride-through and power system frequency modulation.
For example, the invention provides a system and a method for simulating the electromagnetic transient characteristic of the high voltage ride through characteristic of a direct-drive fan, which are disclosed in Chinese patent documents, wherein the publication number of CN112186815A is 1 month and 5 days after 2021, and the system comprises a high voltage ride through judgment module for determining whether the direct-drive fan enters a high voltage ride through state and forming a high-ride through trigger signal; the high-penetration-time current locking module is used for determining whether the direct-drive fan enters a high-voltage penetration state or not, and if so, processing an active current reference signal to obtain an active current high-penetration-time locking value; the high-voltage penetration stage reactive current control module is used for outputting a reactive current instruction value in a high-voltage penetration state or a reactive current reference value in a conventional state as a reactive current instruction value according to a high-voltage penetration trigger signal; and the active current control module in the high penetration stage is used for outputting a conventional current reference value or the active current high penetration moment locking value as an active current instruction value according to a high penetration trigger signal, so that the high voltage penetration characteristic of the actual direct-drive fan can be accurately reproduced. The invention only considers high voltage ride through, does not consider the requirements of low voltage and power system frequency modulation, does not coordinate active balance and reactive support, and does not consider the problem of electric energy quality.
Disclosure of Invention
The wind power generation system is based on wind storage integrated equipment, and aims to improve the adaptability of a wind turbine generator system and the quality of electric energy; a wind turbine transient characteristic improving method based on wind storage integration is provided: the problem of integration of control strategies of the energy storage and wind turbine generator is solved, overcurrent of a wind turbine generator grid side converter in a low-pass process and overcharge/overdischarge of an energy storage battery are avoided, an original high-voltage ride-through algorithm of the wind turbine generator is simplified, power fluctuation of the wind turbine generator is stabilized on the basis of meeting reactive current, and compensation current under a specific frequency band can be selected mainly according to the charge state of the energy storage battery, actual unbalanced current and harmonic current content.
The technical problem of the invention is mainly solved by the following technical scheme:
when the grid-connected point voltage of the wind turbine generator is detected to be in low voltage ride through, the wind storage integrated system is switched to a low-ride through mode, the grid-side converter injects reactive current into the power system, and the energy storage converter is connected to the direct current side of the wind turbine generator;
when the grid-connected point voltage of the wind turbine generator is detected to be in high voltage ride through, the wind storage integrated system is switched to a high-ride-through mode, the grid-side converter executes a scheduling instruction before fault or outputs active power corresponding to the actual wind condition, and the energy storage converter is connected to the alternating current side of the wind turbine generator; when no trigger signal exists, the wind-storage integrated system is in an electric energy quality mode, the grid-side converter operates normally, and the energy storage converter is connected to the alternating current side of the unit to compensate harmonic components and unbalanced components output when the unit operates normally.
The algorithm solves the problem of integration of control strategies of the energy storage and wind turbine generator, can avoid overcurrent of a wind turbine generator grid side converter and overcharge/overdischarge of an energy storage battery in a low-pass process, and can also select compensation current in a specific frequency band according to the charge state of the energy storage battery, actual unbalanced current and harmonic current content.
Preferably, the hardware device of the lifting method comprises a power grid, a transformer, a wind storage converter, a wind turbine generator and a battery, the power grid is connected with the high-voltage side of the transformer, the low-voltage side of the transformer is connected with the output end of the wind storage converter, the energy supply input end of the wind storage converter is connected with the wind turbine generator, the energy storage input end of the wind storage converter is connected with the battery, the wind storage converter comprises an AC/DC converter, a No. 1 DC/AC converter, a No. 2 DC/AC converter, a DC/DC converter, a switch K2 and a switch K3, the output end of the No. 1 DC/AC converter is connected with the low-voltage side of the transformer, the output end of the AC/DC converter is connected with the input end of the No. 1 DC/AC converter, the input end of the AC/DC converter is connected with the wind turbine generator, the output end of the No. 2 DC/AC converter is connected with the second end of the switch K3, a first terminal of the switch K3 is connected to the low voltage side of the transformer, an input terminal of the No. 2 DC/AC converter is connected to an output terminal of the DC/DC converter, an input terminal of the DC/DC converter is connected to the battery, a first terminal of the switch K2 is connected to an output terminal of the AC/DC converter, and a second terminal of the switch K2 is connected to an output terminal of the DC/DC converter. The hardware topological connection structure can obviously improve the adaptability of the wind turbine generator grid and the power quality by matching with the algorithm of the invention.
Preferably, when the grid-connected point voltage of the wind turbine generator is 0.2pu-0.85pu, the wind turbine generator is in low voltage ride through, the control strategy is switched to a low-ride-through mode, and at the moment, the reactive current instruction of the grid-side converter of the wind turbine generator is
Figure BDA0003229144180000021
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000022
dynamic reactive current reference value U injected into wind power generation unit of wind power storage integrated system in low-penetration control modetTo grid point voltage, UtCan also be expressed as per unit value, INRated current for wind turbine generator, K1K can be obtained for the reactive current proportionality coefficient of the wind turbine generator according to the standard1Has a value range of 1.5 to K1≤3.0；
The energy storage converter is connected to the direct current side of the unit, and the control instruction of energy storage is
Figure BDA0003229144180000031
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000032
active power, K, injected into the DC bus for energy storage in a controlled low-penetration modeP1And Ki1Respectively are the parameters of the energy storage voltage outer loop controller PI,
Figure BDA0003229144180000033
Vdcrespectively a given value and an actual measured value of the voltage of the direct current bus. In the algorithm, the low-pass process can be avoidedAnd overcharging/overdischarging the energy storage battery of the wind turbine generator.
Preferably, the K based on the fuzzy controllerP1The selection rule of (1):
when U is turnedtWhen the value is NB: when SOC takes on NB or NS or O or PS or PB, KP1Values are all NB;
when U is turnedtWhen the value is NS: if SOC takes on NB, K P1Taking the value as NB; if SOC takes the value of NS or O or PS or PB, then KP1Taking the value as NS;
when U is turnedtWhen the value is O: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value NS, then KP1Taking the value as NS; if SOC takes on O, PS or PB, then KP1Taking the value as O;
when U is turnedtWhen the value is PS: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value NS, then KP1Taking the value as NS; if SOC takes on the value of O, KP1Taking the value as O; if SOC takes the value of PS or PB, then KP1Taking the value as PS; when U is turnedtWhen the value is PB: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value NS, then KP1Taking the value as NS; if SOC takes on the value of O, KP1Taking the value as O; if SOC takes the value of PS, then KP1Taking the value as PS; if SOC takes the value PB, then KP1Taking the value as PB;
wherein, UtThe voltage range of NB is [0.2, 0.3 ], the voltage range of NS is [0.3, 0.4 ], the voltage range of O is [0.4, 0.6 ], the voltage range of PS is [0.6, 0.7 ], the voltage range of PB is [0.7, 0.8%](ii) a SOC range of NB for SOC fuzzy set is [0.1, 0.3), SOC range of NS for [0.3, 0.4), SOC range of O for [0.4, 0.6), SOC range of PS for [0.6, 0.7), and SOC range of PB for [0.7, 0.9](ii) a K given by per unit valueP1The value ranges of NB in the fuzzy set are [0, 0.1 ], NS is [0.2, 0.3 ], O is [0.3, 0.4 ], PS is [0.4, 0.5 ], PB is [0.5, 0.7 ] ](ii) a Obtaining the active current reference value of the grid-side converter as
Figure BDA0003229144180000034
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000035
an active current reference value of a wind power generating set in a wind power storage integrated system in a low penetration control mode is obtained; i ismaxThe maximum current limit value is the maximum current limit value of the grid-side converter; i isgqThe reactive current is the unit network side reactive current; i iss1And outputting current for energy storage.
The proportional coefficient of the energy storage voltage outer ring controller adopting the algorithm is self-adaptively adjusted based on the fuzzy controller, so that the overcurrent of a wind turbine grid side converter in a low-pass process can be avoided, and the service life of the wind storage integrated system can be prolonged by optimizing parameters through fuzzy control.
Preferably, when the voltage of the grid-connected point of the wind turbine generator is 1.13pu-1.3pu, the wind turbine generator is in high voltage ride through, the control strategy is switched to a high-ride-through mode, and an active and reactive current instruction of a grid-side converter of the wind turbine generator maintains a reactive instruction at the moment before the fault
Figure BDA0003229144180000041
Active command
Figure BDA0003229144180000042
The constant, energy storage system reactive current command is expressed as
Figure BDA0003229144180000043
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000044
dynamic reactive current reference value K absorbed by energy storage equipment in wind storage integrated system to system under control of high penetration mode2K can be obtained for the reactive current proportionality coefficient of the wind turbine generator according to the standard2Has a value range of K2≥1.5；
In the high voltage ride through process, the high-time charge-discharge reference power of the energy storage equipment is designed based on the first-order low-pass filter, and can be specifically expressed as
Figure BDA0003229144180000045
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000046
active power, P, injected into the system in a controlled high-penetration mode for energy storageeWind turbine generator output power, T, for consideration of wind resource characteristics and rotor speed constraintssIs a time constant related to the control delay of the wind turbine converter.
In the algorithm, energy storage equipment absorbs dynamic reactive current and simultaneously needs to stabilize active power fluctuation, the output power of the wind turbine generator controlled by the converter can be regarded as a delay link, the high-penetration control strategy of the wind turbine generator is simplified, and overcurrent of the grid-side converter is avoided on the basis of meeting the reactive current.
Preferably, when the grid voltage vector d-axis is oriented, the reference value of the active current of the energy storage converter is expressed as
Figure BDA0003229144180000047
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000048
the method comprises the steps that an active current reference value is injected into a wind storage integrated system by energy storage equipment in the wind storage integrated system in a high penetration control mode; egdAnd d-axis voltage of three-phase voltage at the wind turbine end is converted based on Park.
The algorithm can stabilize power fluctuation to a certain extent and attach importance to the flow characteristics of active power during a fault period.
Preferably, when the per unit value of the wind turbine generator is 0.85pu-1.13pu, the wind turbine generator is in the power quality mode, and when the three-phase current of the power grid contains harmonic components and asymmetric components, the expression under the three-phase stationary coordinate system is
Figure BDA0003229144180000049
Figure BDA00032291441800000410
Figure BDA0003229144180000051
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000052
respectively being effective values of positive sequence component and negative sequence component of power grid current under different frequency multiplication
Figure BDA0003229144180000053
The initial phases of the power grid current under different frequency multiplication are respectively set; omega0Is the system fundamental frequency; n is the harmonic frequency; cabc-αβClark transformation matrix representing constant power, in particular as
Figure BDA0003229144180000054
In the algorithm, Clark transformation converts vectors in a static coordinate system into equivalent vectors in a static two-phase coordinate system, so that the same front and back magnetic field dynamics can be ensured.
Preferably, the expression of the grid current containing the harmonic component and the asymmetric component in the two-phase stationary coordinate system is
Figure BDA0003229144180000055
Preferably, when the output capacity of the energy storage system is smaller than the calculated capacity, the energy storage system performs limited output compensation according to the actual unbalanced current and harmonic current content, and the system SOC calculation mode can be expressed as
Figure BDA0003229144180000056
In the formula, SOCiniThe state of charge of the system at the moment; t is the discharge time; and C is the battery capacity.
The algorithm is used for calculating the charge state of the energy storage battery and providing parameter support for the power quality mode control strategy.
Preferably, the controller comprises a proportional resonant controller, and the algorithm of the proportional resonant controller is
Figure BDA0003229144180000057
In the formula, VPRThe output quantity of the proportional resonant controller is modulated with the triangular wave to generate a trigger pulse of the switching device; i is err(s) is a representation of the difference between the reference current and the actual current in the complex domain; n omega0The unbalanced current and harmonic current components to be compensated; omegacIs the frequency response width; k is a radical ofrnAn integral parameter of the nth harmonic; the current compensation component determination principle based on the energy storage SOC is as follows:
when the SOC value range is (0, 20), the current compensation component does not take a value;
when the SOC value range is (20, 30), the current compensation component is Max 1;
when the SOC value range is (30, 40), the current compensation components are Max1 and Max 2;
when the SOC value range is (40, 50), the current compensation components are Max1, Max2 and Max 3;
when the SOC value range is (50, 60), the current compensation components are Max1 and Max2 and Max3 and Max 4;
when the SOC value range is (60, 70), the current compensation components are Max1 and Max2 and Max3 and Max4 and Max 5;
when the SOC value range is (70, 80), the current compensation components are Max1, Max2, Max3, Max4, Max5 and Max 6;
when the SOC value range is (80,100), the current compensation component takes all values;
max1 is the current component with the highest content in the harmonic waves; max2 is the highest current component in the harmonic wave after Max1 is removed; max3 is the current component with the highest content in the harmonic wave after removing Max1 and Max 2; max4 is the highest current component in the harmonic after removing Max1, Max2 and Max 3; max5 is the highest current component in the harmonic after removing Max1 and Max2 and Max3 and Max 4; max6 is the highest current component in the harmonic after removing Max1 and Max2 and Max3 and Max4 and Max 5.
The compensation current under the specific frequency band is selected according to the charge state of the energy storage battery, the actual unbalanced current and the harmonic current content, so that the transient characteristic of the unit is improved, and the service life of the wind storage integrated system is prolonged
The invention has the beneficial effects that:
1. the method comprises the steps that algorithm strategy integration is carried out on a fault ride-through control algorithm and a power quality control algorithm of an energy storage and wind turbine generator based on wind storage integrated hardware topology, unified coordination of a wind storage integrated control system is achieved, and transient characteristics of the wind turbine generator are improved;
2. in the low-penetration process, the capacity of a grid-side converter of the wind turbine generator and the charge state of an energy storage battery are used as control references, a parameter self-adaptive fuzzy controller is established, overcurrent of the grid-side converter of the wind turbine generator and overcharge/overdischarge of the energy storage battery in the low-penetration process are avoided, and the service life of a wind storage integrated system is prolonged;
3. the energy storage equipment is utilized to realize a high voltage ride through control strategy, the high ride through control strategy of the wind turbine generator is simplified, the grid-side converter is prevented from overflowing on the basis of meeting the reactive current, and the algorithm stabilizes the power fluctuation to a certain extent and attaches importance to the flow characteristic of active power during the fault period;
4. when harmonic current and unbalanced current are restrained (in a power quality mode), a control strategy is used for mainly selecting compensating current under a specific frequency band according to the charge state of the energy storage battery, actual unbalanced current and harmonic current content, so that the transient characteristic of a unit is improved, and the service life of the wind storage integrated system is prolonged.
Drawings
Fig. 1 is a wind storage integrated hardware topological diagram of a wind turbine transient characteristic improving method based on wind storage integration.
Fig. 2 is a flow chart of a joint control strategy of the wind turbine transient characteristic improving method based on wind storage integration.
Fig. 3 is a wind energy storage integrated system control strategy diagram of a wind turbine transient characteristic improving method based on wind energy storage integration.
Fig. 4 is a schematic diagram of detection of unbalanced current and harmonic current of the wind turbine transient characteristic improving method based on wind storage integration.
In the figure, 1 is a power grid, 2 is a transformer, 3 is a wind storage converter, 4 is a wind turbine generator and 5 is a battery.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.
Example (b):
in this embodiment, a wind turbine transient characteristic improving method based on wind storage integration, as shown in fig. 1, includes
When the wind turbine generator is detected to be in low voltage ride through, the wind storage integrated system is switched to a low-ride through mode, the grid-side converter injects reactive current into the power system to support voltage recovery, and the energy storage converter is connected to the direct current side of the wind turbine generator to stabilize direct current bus voltage;
When the wind turbine generator is detected to be in high voltage ride through, the wind storage integrated system is switched to a high-voltage ride through mode, the grid-side converter executes a scheduling instruction before fault or outputs active power corresponding to actual wind conditions, and the energy storage converter is connected to the alternating current side of the wind turbine generator to absorb dynamic reactive current and simultaneously stabilize active power fluctuation;
when no trigger signal exists, namely the wind turbine generator is not in a fault ride-through state, the wind storage integrated system is in an electric energy quality mode, the grid-side converter operates normally, and the energy storage converter is connected to the alternating current side of the generator to compensate harmonic components and unbalanced components output by the generator during normal operation. The low-pass mode is mode 1, the high-pass mode is mode 2, and the power quality mode is mode 3.
In the three modes, the control strategies of the grid-side converter and the energy storage converter need to be selected by considering the actual condition of the power grid, and the control strategy of the machine-side converter can adopt any one of current source control strategies or voltage source control strategies.
Wind storage integrated hardware topological diagram, as shown in fig. 1, a wind turbine generator 4 is connected with a wind storage converter 3 as an energy supply input end, a battery 5 is connected with the wind storage converter 3 as an energy storage input end, the wind storage converter 3 outputs 690V voltage to be connected with the low-voltage side of a transformer 2, the high-voltage side of the transformer 2 is connected with a power grid 1 through a 35kV (or 10kV) current collection circuit, wherein the wind storage converter 3 comprises an AC/DC converter, a No. 1 DC/AC converter, a No. 2 DC/AC converter, a DC/DC converter, a switch K2 and a switch K3, the output end of the No. 1 DC/AC converter is connected with the low-voltage side of the transformer 2, the output end of the AC/DC converter is connected with the input end of the No. 1 DC/AC converter, the input end of the AC/DC converter is connected with the wind turbine generator 4, the output end of the No. 2 DC/AC converter is connected with the second end of the switch K3, a first terminal of the switch K3 is connected to the low-voltage side of the transformer 2, an input terminal of the No. 2 DC/AC converter is connected to an output terminal of the DC/DC converter, an input terminal of the DC/DC converter is connected to the battery 5, a first terminal of the switch K2 is connected to an output terminal of the DC/AC converter, a second terminal of the switch K2 is connected to an output terminal of the DC/DC converter, the switch K2 is closed when the system is switched to the mode 1, the switch K3 is opened, the switch K3 is closed when the system is switched to the mode 2 or the mode 3, and the switch K2 is opened.
The flow chart of the combined control strategy is shown in fig. 2, and the method comprises the steps of firstly starting to start the wind storage integrated equipment, and detecting the grid-connected point voltage U of the wind turbine generator after the system is startedtIf the power grid does not have high-low penetration or the unit fails, the system can stably run in a mode 3, if the unit fails, the wind storage integrated equipment stops running, and then the operation is finished, and if the power grid does have high-low penetration, the grid-connected point voltage U of the wind turbine needs to be judgedt: if 0.85 < UtIf the current value is less than 1.13, switching back to the mode 3; if U is presenttU is not more than 0.85t< 1.13 but satisfy UtLess than or equal to 0.85, and simultaneously satisfies UtIf the current value is less than 0.2, the wind storage integrated equipment is directly stopped, and then the system is ended, but the U is mettLess than or equal to 0.85 and simultaneously satisfies that U is less than or equal to 0.2tThe system will switch to mode 1, and after the algorithm strategy of mode 1 is implemented, if U is presenttIf U is greater than 0.9, the system will switch to mode 3tIf the value is less than or equal to 0.9, the system is switched to the algorithm strategy of the mode 1 again, and the operation is repeated; if U is presenttU is not more than 0.85tIf < 1.13, U is not satisfiedtLess than or equal to 0.85 and satisfies UtIf the number of the U is more than 1.3, the wind storage integrated equipment is directly stopped, and then the system is ended, if the number of the U is more than or equal to 1.13tAnd less than or equal to 1.3, the system is switched to a mode 2, and after the algorithm strategy of the mode 2 is carried out, if U is in use tIf < 1.08, the system will switch to mode 3, otherwise it will switch to mode 2.
The control strategy of the wind energy storage integrated system is shown in FIG. 3, wherein M1 represents a mode 1, M2 represents a mode 2, M3 represents a mode 3, and the three-phase voltage E at the low-voltage side of the transformer 3gabcAnd three-phase current I of power gridgabcAfter being transformed by Park, the phase-locked loop is rotated into two-phase voltage EgdqAnd two-phase current IgdqTwo-phase voltage EgdqAnd current IgdqAnd entering the PI parameter of the current inner loop controller. When the system mode is switched to the mode 1, the switch K2 is closed, the switch K3 is opened, all the switches in the figure are switched to M1, and the upper right per unit value in the figure is 0.8-UtThen, by the algorithm
Figure BDA0003229144180000081
Can obtain the reactive current instruction of the network side converter
Figure BDA0003229144180000082
Passing algorithm
Figure BDA0003229144180000083
Can obtain the active current instruction
Figure BDA0003229144180000084
Reactive current command
Figure BDA0003229144180000085
And active current command
Figure BDA0003229144180000086
After passing through the current inner loop controller, two-phase voltage is output
Figure BDA0003229144180000087
After Park conversion, the three-phase voltage is obtained
Figure BDA0003229144180000088
Three-phase voltage
Figure BDA0003229144180000089
After PWM modulation, the signal is used as a switching signal of a DC/AC converter. After the switch K2 is closed, the DC/AC converter is communicated with the DC/DC converter, and the voltage given value of the direct current bus is
Figure BDA00032291441800000810
Subtracting the actual measured value V of the DC bus voltagedcAfter passing through the adaptive PI controller, the direct current bus active power is converted into active power injected into the direct current bus
Figure BDA00032291441800000811
Figure BDA00032291441800000812
After passing through a PI controller
Figure BDA00032291441800000813
Figure BDA00032291441800000814
PWM modulated by PI controller to be used as switching signal of DC/DC converter, a capacitor connected in parallel with DC/AC converter and having voltage V at both endsdc。
When the system mode is switched to the mode 2, the switch K2 is opened, the switch K3 is closed, and the active and reactive current commands of the grid-side converter maintain the reactive current commands at the moment before the fault
Figure BDA00032291441800000815
Active current command
Figure BDA00032291441800000816
Reactive current command
Figure BDA00032291441800000817
And active current command
Figure BDA00032291441800000818
After passing through the current inner loop controller, two-phase voltage is output
Figure BDA00032291441800000819
After Park conversion, the three-phase voltage is obtained
Figure BDA00032291441800000820
Three-phase voltage
Figure BDA00032291441800000821
After PWM modulation, the signal is used as a switching signal of a DC/AC converter. Reactive current instruction algorithm of energy storage system
Figure BDA00032291441800000822
Active current instruction algorithm of energy storage converter
Figure BDA0003229144180000091
Passing through a current inner loop controller, PWM modulating the voltage to be used as a switching signal of a DC/AC converter, connecting a capacitor in parallel with the DC/AC converter, wherein the voltage at two ends of the capacitor is VdcsCurrent is Idcs. Value of reference voltage
Figure BDA0003229144180000092
Minus the actual voltage value VdcsAfter passing through a PI controller
Figure BDA0003229144180000093
Figure BDA0003229144180000094
And the signal is used as a switching signal of the DC/DC converter after being subjected to PWM modulation by the PI controller.
When the system mode is switched to the mode 3, the switch K2 is switched off, the switch K3 is switched on, the per unit value of the reactive current instruction in the mode 3 is 0, and the given value of the direct-current bus voltage is set to be 0
Figure BDA0003229144180000095
Subtracting the actual measured value V of the DC bus voltagedcAfter passing through a PI controller, the two-phase voltage is output through a current inner loop controller
Figure BDA0003229144180000096
After Park conversion, the three-phase voltage is obtained
Figure BDA0003229144180000097
Three-phase voltage
Figure BDA0003229144180000098
After PWM modulation, the signal is used as a switching signal of a DC/AC converter. Value of reference voltage
Figure BDA0003229144180000099
Minus the actual voltage value VdcsAfter passing through a PI controller
Figure BDA00032291441800000910
Figure BDA00032291441800000911
And after passing through the PI controller, the signal is used as a switching signal of the DC/DC converter after PWM modulation. Reference value i of harmonic, reactive and unbalanced negative sequence component compensation current in wind storage integrated system under alpha beta coordinate systemαβhMinus the actual value iαβsGeneration of Ierr(s) passing an algorithm
Figure BDA00032291441800000912
VPRIs the output of a proportional resonant controller, VPRAfter being modulated by PMW, the signal is used as a DC/AC switching signalA capacitor is connected in parallel with the DC/AC converter, the voltage across the capacitor is VdcsCurrent is Idcs。
1. Low penetration mode control strategy (mode 1)
When the wind turbine generator is detected to be in low voltage ride through, the control strategy is switched to a mode 1, and at the moment, the reactive current instruction of the grid-side converter of the wind turbine generator is
Figure BDA00032291441800000913
In the formula (I), the compound is shown in the specification,
Figure BDA00032291441800000914
a dynamic reactive current reference value is injected into the wind power generation unit of the wind power storage integrated system in a control mode 1; u shapetIs the voltage or per unit value of the grid-connected point; i isNRated current of the wind turbine generator; k 1K can be obtained for the reactive current proportionality coefficient of the wind turbine generator according to the standard1Has a value range of 1.5 to K1≤3.0。
The energy storage converter is connected to the direct current side of the unit, K2 is closed to stabilize the bus voltage, and at the moment, the control instruction of energy storage is
Figure BDA00032291441800000915
In the formula (I), the compound is shown in the specification,
Figure BDA00032291441800000916
active power injected to the direct current bus in a low-penetration mode is stored; kP1And Ki1Respectively are energy storage voltage outer loop controller PI parameters;
Figure BDA00032291441800000917
Vdcrespectively a given value and an actual measured value of the voltage of the direct current bus.
When the system voltage is lower, the reactive current required to be injected into the system by the wind turbine generator is higher, if the stored energy is discharged too much, the grid-side converter is over-current, and the wind turbine generator is not favorable for completing low-voltage ride through; when the state of charge (SOC) of the stored energy is too low, if the control coefficient is not changed, the stored energy is easily over-discharged, which is not beneficial to the safe and stable operation of the wind-storage integrated system, therefore, the capacity of the wind turbine grid-side converter and the SOC of the energy storage battery (the energy storage battery is not limited to electrochemical energy storage, but also comprises mechanical energy storage and electromagnetic energy storage) should be considered at the same time, the proportional coefficient of the energy storage voltage outer ring controller is adaptively adjusted based on the fuzzy controller, and the control rule is as follows
TABLE 1 fuzzy controller based KP1 selection rules
Figure BDA0003229144180000101
Wherein, UtThe voltage range of NB is [0.2, 0.3 ], the voltage range of NS is [0.3, 0.4 ], the voltage range of O is [0.4, 0.6 ], the voltage range of PS is [0.6, 0.7 ], the voltage range of PB is [0.7, 0.8%](ii) a SOC range of NB for SOC fuzzy set is [0.1, 0.3), SOC range of NS for [0.3, 0.4), SOC range of O for [0.4, 0.6), SOC range of PS for [0.6, 0.7), and SOC range of PB for [0.7, 0.9](the SOC range should be referred to the SOC upper and lower limits specified by the battery manufacturer, which is only an example); k given by per unit valueP1The value ranges of NB in the fuzzy set are [0, 0.1 ], NS is [0.2, 0.3 ], O is [0.3, 0.4 ], PS is [0.4, 0.5 ], PB is [0.5, 0.7 ]]If the input of the controller is a named value, the rated voltage of the output end of the energy storage DC/DC converter is taken as a voltage reference value UbaseThe stored energy output power is a power reference value PbaseAnd performing per unit value conversion on the parameters by using the reference value: such as KP1When 0.1 is given as a per unit value, it means that when the voltage at the output terminal of the voltage DC/DC converter rises by 0.2UbaseWhile, the power reference value is changed by 0.02Pbase。
The finally obtained active current reference value of the grid-side converter is
Figure BDA0003229144180000102
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000103
the active current reference value of a wind power generating set in the wind power storage integrated system is controlled in a control mode 1; i is maxThe maximum current limit value is the maximum current limit value of the grid-side converter; i isgdThe reactive current is the unit network side reactive current; i iss1And outputting current for energy storage.
2. High penetration mode control strategy (mode 2)
When detecting that the wind turbine generator is in high voltage ride through, the control strategy is switched to a mode 2, and at the moment, a reactive and active current instruction of a grid-side converter of the wind turbine generator maintains a reactive and active instruction at the moment before the fault
Figure BDA0003229144180000104
The constant, energy storage system reactive current command is expressed as
Figure BDA0003229144180000105
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000106
the method comprises the steps that a dynamic reactive current reference value absorbed by energy storage equipment in the wind storage integrated system to the system in a control mode 2 is obtained; k2K can be obtained for the reactive current proportionality coefficient of the wind turbine generator according to the standard2Has a value range of K2≥1.5。
In the high voltage ride through process, the energy storage device absorbs dynamic reactive current and simultaneously needs to stabilize active power fluctuation, and the output power of the wind turbine generator controlled by the converter can be regarded as a delay link, so that the high-time charge-discharge reference power of the energy storage device can be designed based on a first-order low-pass filter, and can be specifically expressed as charge-discharge reference power in high pass
Figure BDA0003229144180000111
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000112
active power injected into the system for energy storage in the control mode 2; peThe wind turbine generator set output power is the wind turbine generator set output power which is restrained by considering wind resource characteristics and rotor rotating speed; t issIs a time constant related to the control delay of the wind turbine converter.
When the grid voltage vector d-axis orientation is based, the reference value of the active current of the energy storage converter can be expressed as
Figure BDA0003229144180000113
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000114
the method comprises the steps of injecting an active current reference value into a wind storage integrated system by energy storage equipment in a control mode 2; egdAnd d-axis voltage of three-phase voltage at the wind turbine end is converted based on Park.
3. Power quality mode control strategy (mode 3)
Firstly, a synchronous rotation angle is determined based on positive sequence voltage, then Park and other transformations are carried out through the rotation angle to obtain compensation current containing harmonic, reactive and unbalanced fundamental wave negative sequence components, and finally, frequency division control is carried out on each harmonic and fundamental wave component according to the capacity of an energy storage converter, so that limited current harmonic and current imbalance compensation is achieved, and the electric energy quality of a unit is improved.
In FIG. 4, dq-1Represents the inverse dq transformation; i.e. idqRepresenting active and reactive currents in the form of direct current, and harmonics in the current (from i)αβHarmonic, reactive, and unbalanced negative sequence components); LPF (Low Pass Filter) is a low Pass filter; i.e. idq-dcDirect current active current and reactive current without harmonic waves; i.e. iαβhAnd compensating the reference value of the current of the harmonic, reactive and unbalanced negative sequence components in the wind storage integrated system under an alpha beta coordinate system.
The positive sequence voltage extraction method for filtering out the alternating current component is not limited, but the phase-locked deviation caused by the conditions of three-phase voltage unbalance, voltage harmonic waves, voltage amplitude, frequency mutation and the like to the phase angle is considered in the positive sequence voltage extraction; when the three-phase current of the power grid contains harmonic components and asymmetric components, the expression under the three-phase static coordinate system is
Figure BDA0003229144180000115
Figure BDA0003229144180000116
Figure BDA0003229144180000117
In the formula (I), the compound is shown in the specification,
Figure BDA0003229144180000121
respectively being effective values of positive sequence component and negative sequence component of power grid current under different frequency multiplication
Figure BDA0003229144180000122
The initial phases of the power grid current under different frequency multiplication are respectively set; omega0Is the system fundamental frequency; n is the harmonic frequency; cabc-αβClark transformation matrix representing constant power, in particular as
Figure BDA0003229144180000123
Therefore, the expression of the grid current containing the harmonic component and the asymmetric component in the two-phase stationary coordinate system is
Figure BDA0003229144180000124
Since the PI controller can only track the dc component by reducing the error, and cannot track the ac component, the proportional resonant controller can be used to track the ac flow.
In this control mode, the SOC of the energy storage system also needs to be considered: when the output capacity of the energy storage system is larger than the calculated capacity to be compensated, the energy storage system directly follows the reference value of the compensation current; when the output capacity of the energy storage system is smaller than the calculated capacity, the energy storage system carries out limited output compensation according to the actual unbalanced current and harmonic current content, and the SOC calculation mode of the system can be expressed as
Figure BDA0003229144180000125
In the formula, SOCiniThe state of charge of the system at the moment; t is the discharge time, the duration of the short-time harmonic wave defined in the standard GB/T14549 & 1993 power quality public power grid harmonic wave does not exceed 2s, and the discharge time is selected to be 2s (the discharge time can be selected again according to the time according to different references); and C is the battery capacity.
The proportional resonant controller algorithm may be expressed as
Figure BDA0003229144180000126
In the formula, VPRThe output quantity of the proportional resonant controller is modulated with the triangular wave to generate a trigger pulse of the switching device; i iserr(s) is a representation of the difference between the reference current and the actual current in the complex domain; n omega0The unbalanced current and harmonic current components to be compensated; omegacThe original gain range can be enlarged for the frequency response width; k is a radical ofrnIs an integral parameter of the nth harmonic.
The control law between the SOC and the compensation current is shown in the following table, when the SOC is lower than 20%, no current compensation is performed, and when the SOC is higher than 80%, all unbalanced currents and harmonic currents are compensated, that is, the energy storage system directly follows the reference value of the compensation current.
TABLE 2 Current Compensation component determination principles based on energy storage SOC
Figure BDA0003229144180000131
In the table, Max1 is the highest current component in the harmonic; max2 is the highest current component in the harmonic wave after Max1 is removed; max3 is the current component with the highest content in the harmonic wave after removing Max1 and Max 2; max4 is the highest current component in the harmonic after removing Max1, Max2 and Max 3; max5 is the highest current component in the harmonic after removing Max1 and Max2 and Max3 and Max 4; max6 is the highest current component in the harmonic after removing Max1 and Max2 and Max3 and Max4 and Max 5.
In the invention, the grid-connected point voltage is taken as a switching condition between a fault ride-through control algorithm and a power quality control algorithm, and three control strategies are provided: a low-penetration mode control strategy, a high-penetration mode control strategy and a power quality mode control strategy. The low-pass mode control strategy can avoid overcurrent of a wind generator set network side converter and overcharge/overdischarge of an energy storage battery in a low-pass process; the high-penetration mode control strategy simplifies the original high-voltage ride-through algorithm of the wind turbine generator, and stabilizes the power fluctuation of the wind turbine generator on the basis of meeting the reactive current; the electric energy quality mode control strategy is used for mainly selecting the compensation current in a specific frequency band according to the charge state of the energy storage battery, the actual unbalanced current and the harmonic current content.
It should be understood that the examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Claims (10)

1. A wind turbine transient characteristic improving method based on wind storage integration is characterized in that,
when the grid-connected point voltage of the wind turbine generator is detected to be in low voltage ride through, the wind storage integrated system is switched to a low-ride through mode, the grid-side converter injects reactive current into the power system, and the energy storage converter is connected to the direct current side of the wind turbine generator;
When the grid-connected point voltage of the wind turbine generator is detected to be in high voltage ride through, the wind storage integrated system is switched to a high-ride-through mode, the grid-side converter executes a scheduling instruction before fault or outputs active power corresponding to the actual wind condition, and the energy storage converter is connected to the alternating current side of the wind turbine generator;
when no trigger signal exists, the wind-storage integrated system is in an electric energy quality mode, the grid-side converter operates normally, and the energy storage converter is connected to the alternating current side of the unit to compensate harmonic components and unbalanced components output when the unit operates normally.
2. The wind turbine generator transient characteristic improving method based on wind storage integration of claim 1, wherein the hardware devices of the improving method comprise a power grid, a transformer, a wind storage converter, a wind turbine generator and a battery, the power grid is connected to the high-voltage side of the transformer, the low-voltage side of the transformer is connected to the output end of the wind storage converter, the energy supply input end of the wind storage converter is connected to the wind turbine generator, the energy storage input end of the wind storage converter is connected to the battery, the wind storage converter comprises an AC/DC converter, a No. 1 DC/AC converter, a No. 2 DC/AC converter, a DC/DC converter, a switch K2 and a switch K3, the output end of the No. 1 DC/AC converter is connected to the low-voltage side of the transformer, the output end of the AC/DC converter is connected to the input end of the No. 1 DC/AC converter, the input end of the AC/DC converter is connected with the wind turbine generator, the output end of the No. 2 DC/AC converter is connected with the second end of the switch K3, the first end of the switch K3 is connected with the low-voltage side of the transformer, the input end of the No. 2 DC/AC converter is connected with the output end of the DC/DC converter, the input end of the DC/DC converter is connected with the battery, the first end of the switch K2 is connected with the output end of the AC/DC converter, and the second end of the switch K2 is connected with the output end of the DC/DC converter.
3. The wind turbine generator transient characteristic improving method based on wind storage integration according to claim 1, wherein when the grid-connected point voltage of the wind turbine generator is 0.2pu-0.85pu, the wind turbine generator is in low voltage ride through, the control strategy is switched to a low-ride-through mode, and at the moment, the reactive current instruction of the grid-side converter of the wind turbine generator is
Figure FDA0003229144170000011
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000012
dynamic reactive current reference value U injected into wind power generation unit of wind power storage integrated system in low-penetration control modetTo grid point voltage, UtCan also be expressed as per unit value, INRated current for wind turbine generator, K1K can be obtained for the reactive current proportionality coefficient of the wind turbine generator according to the standard1Has a value range of 1.5 to K1≤3.0；
The energy storage converter is connected to the direct current side of the unit, and the control instruction of energy storage is
Figure FDA0003229144170000021
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000022
active power, K, injected into the DC bus for energy storage in a controlled low-penetration modeP1And Ki1Respectively are the parameters of the energy storage voltage outer loop controller PI,
Figure FDA0003229144170000023
Vdcrespectively a given value and an actual measured value of the voltage of the direct current bus.
4. The wind turbine generator transient characteristic improving method based on wind storage integration according to claim 3, wherein K is based on a fuzzy controllerP1The selection rule of (1):
when U is turnedtWhen the value is NB: when SOC takes on NB or NS or O or PS or PB, K P1All values are NB；
When U is turnedtWhen the value is NS: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value of NS or O or PS or PB, then KP1Taking the value as NS;
when U is turnedtWhen the value is O: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value NS, then KP1Taking the value as NS; if SOC takes on O, PS or PB, then KP1Taking the value as O;
when U is turnedtWhen the value is PS: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value NS, then KP1Taking the value as NS; if SOC takes on the value of O, KP1Taking the value as O; if SOC takes the value of PS or PB, then KP1Taking the value as PS;
when U is turnedtWhen the value is PB: if SOC takes on NB, KP1Taking the value as NB; if SOC takes the value NS, then KP1Taking the value as NS; if SOC takes on the value of O, KP1Taking the value as O; if SOC takes the value of PS, then KP1Taking the value as PS; if SOC takes the value PB, then KP1Taking the value as PB;
wherein, UtThe voltage range of NB is [0.2, 0.3 ], the voltage range of NS is [0.3, 0.4 ], the voltage range of O is [0.4, 0.6 ], the voltage range of PS is [0.6, 0.7 ], the voltage range of PB is [0.7, 0.8%](ii) a SOC range of NB for SOC fuzzy set is [0.1, 0.3), SOC range of NS for [0.3, 0.4), SOC range of O for [0.4, 0.6), SOC range of PS for [0.6, 0.7), and SOC range of PB for [0.7, 0.9 ](ii) a K given by per unit valueP1The value ranges of NB in the fuzzy set are [0, 0.1 ], NS is [0.2, 0.3 ], O is [0.3, 0.4 ], PS is [0.4, 0.5 ], PB is [0.5, 0.7 ]](ii) a Obtaining the active current reference value of the grid-side converter as
Figure FDA0003229144170000031
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000032
an active current reference value of a wind power generating set in a wind power storage integrated system in a low penetration control mode is obtained; i ismaxThe maximum current limit value is the maximum current limit value of the grid-side converter; i isgqThe reactive current is the unit network side reactive current; i iss1And outputting current for energy storage.
5. The wind turbine generator transient characteristic improving method based on wind storage integration according to claim 1, wherein when the grid-connected point voltage of the wind turbine generator is 1.13pu-1.3pu, the wind turbine generator is in high voltage ride through, the control strategy is switched to a high ride through mode, and the grid-side converter of the wind turbine generator maintains a reactive instruction at a moment before a fault due to active and reactive current instructions of a grid-side converter
Figure FDA0003229144170000033
Active command
Figure FDA0003229144170000034
The constant, energy storage system reactive current command is expressed as
Figure FDA0003229144170000035
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000036
dynamic reactive current reference value K absorbed by energy storage equipment in wind storage integrated system to system under control of high penetration mode2K can be obtained for the reactive current proportionality coefficient of the wind turbine generator according to the standard 2Has a value range of K2≥1.5；
In the high voltage ride through process, the high-time charge-discharge reference power of the energy storage equipment is designed based on the first-order low-pass filter, and can be specifically expressed as
Figure FDA0003229144170000037
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000041
active power, P, injected into the system in a controlled high-penetration mode for energy storageeWind turbine generator output power, T, for consideration of wind resource characteristics and rotor speed constraintssIs a time constant related to the control delay of the wind turbine converter.
6. The wind turbine generator transient characteristic improving method based on wind-storage integration according to claim 5, wherein when the grid voltage vector d-axis orientation is based, the reference value of the active current of the energy storage converter is expressed as
Figure FDA0003229144170000042
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000043
the method comprises the steps that an active current reference value is injected into a wind storage integrated system by energy storage equipment in the wind storage integrated system in a high penetration control mode; egdAnd d-axis voltage of three-phase voltage at the wind turbine end is converted based on Park.
7. The wind turbine generator transient characteristic improving method based on wind-storage integration according to claim 1, wherein when the grid-connected point voltage of the wind turbine generator is 0.85pu-1.13pu, the wind turbine generator is in a power quality mode, and when the three-phase current of the power grid contains harmonic components and asymmetric components, the expression under the three-phase stationary coordinate system is
Figure FDA0003229144170000044
Figure FDA0003229144170000045
Figure FDA0003229144170000046
In the formula (I), the compound is shown in the specification,
Figure FDA0003229144170000047
respectively being effective values of positive sequence component and negative sequence component of power grid current under different frequency multiplication
Figure FDA0003229144170000048
The initial phases of the power grid current under different frequency multiplication are respectively set; omega0Is the system fundamental frequency; n is the harmonic frequency; cabc-αβClark transformation matrix representing constant power, in particular as
Figure FDA0003229144170000049
8. The wind turbine generator transient characteristic improving method based on wind-storage integration according to claim 7, wherein the expression of the grid current containing the harmonic component and the asymmetric component in the two-phase stationary coordinate system is
Figure FDA0003229144170000051
9. The wind turbine generator transient characteristic improving method based on wind-storage integration according to claim 8, wherein when the output capacity of the energy storage system is smaller than the calculated capacity, the energy storage system performs limited output compensation according to the actual unbalanced current and harmonic current content, and the system SOC calculation mode can be expressed as
Figure FDA0003229144170000052
In the formula, SOCiniThe state of charge of the system at the moment; t is the discharge time; and C is the battery capacity.
10. The wind turbine generator transient characteristic improving method based on wind storage integration according to claim 7, wherein the algorithm of the proportional resonant controller is
Figure FDA0003229144170000053
In the formula, VPRIs the output of a proportional resonant controller, V PRThe trigger pulse of the switching device can be generated by modulating the triangular wave; i iserr(s) is a representation of the difference between the reference current and the actual current in the complex domain; n omega0The unbalanced current and harmonic current components to be compensated; omegacIs the frequency response width; k is a radical ofrnAn integral parameter of the nth harmonic; the current compensation component determination principle based on the energy storage SOC is as follows:
when the SOC value range is (0, 20), the current compensation component does not take a value;
when the SOC value range is (20, 30), the current compensation component is Max 1;
when the SOC value range is (30, 40), the current compensation components are Max1 and Max 2;
when the SOC value range is (40, 50), the current compensation components are Max1, Max2 and Max 3;
when the SOC value range is (50, 60), the current compensation components are Max1 and Max2 and Max3 and Max 4;
when the SOC value range is (60, 70), the current compensation components are Max1 and Max2 and Max3 and Max4 and Max 5;
when the SOC value range is (70, 80), the current compensation components are Max1, Max2, Max3, Max4, Max5 and Max 6;
when the SOC value range is (80, 100), the current compensation component takes all values;
max1 is the current component with the highest content in the harmonic waves; max2 is the highest current component in the harmonic wave after Max1 is removed; max3 is the current component with the highest content in the harmonic wave after removing Max1 and Max 2; max4 is the highest current component in the harmonic after removing Max1, Max2 and Max 3; max5 is the highest current component in the harmonic after removing Max1 and Max2 and Max3 and Max 4; max6 is the highest current component in the harmonic after removing Max1 and Max2 and Max3 and Max4 and Max 5.
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Cited By (3)

* Cited by examiner, † Cited by third party
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CN114362208A (en) * 2022-01-07 2022-04-15 阳光电源股份有限公司 Energy storage wind power converter and control method thereof
CN115249979A (en) * 2022-07-07 2022-10-28 华北电力科学研究院有限责任公司 Fault ride-through control method and device for double-fed wind turbine generator in weak grid condition
WO2023231252A1 (en) * 2022-05-31 2023-12-07 金风科技股份有限公司 Control method for wind turbine generator system and wind turbine generator system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114362208A (en) * 2022-01-07 2022-04-15 阳光电源股份有限公司 Energy storage wind power converter and control method thereof
WO2023231252A1 (en) * 2022-05-31 2023-12-07 金风科技股份有限公司 Control method for wind turbine generator system and wind turbine generator system
CN115249979A (en) * 2022-07-07 2022-10-28 华北电力科学研究院有限责任公司 Fault ride-through control method and device for double-fed wind turbine generator in weak grid condition
CN115249979B (en) * 2022-07-07 2024-04-26 华北电力科学研究院有限责任公司 Fault ride-through control method and device for doubly-fed wind turbine generator under weak current network working condition

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