CN104022529A - Doubly-fed wind generator low voltage ride through control method based on improved Crowbar - Google Patents

Doubly-fed wind generator low voltage ride through control method based on improved Crowbar Download PDF

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Publication number
CN104022529A
CN104022529A CN201410264872.9A CN201410264872A CN104022529A CN 104022529 A CN104022529 A CN 104022529A CN 201410264872 A CN201410264872 A CN 201410264872A CN 104022529 A CN104022529 A CN 104022529A
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CN
China
Prior art keywords
voltage
circuit
crowbar
double
control
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CN201410264872.9A
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Chinese (zh)
Inventor
张建华
丁磊
沈浩然
戴春蕾
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张建华
丁磊
沈浩然
戴春蕾
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Application filed by 张建华, 丁磊, 沈浩然, 戴春蕾 filed Critical 张建华
Priority to CN201410264872.9A priority Critical patent/CN104022529A/en
Publication of CN104022529A publication Critical patent/CN104022529A/en

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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • Y02E10/76Power conversion electric or electronic aspects

Abstract

The invention provides a doubly-fed type wind-power-improved Crowbar circuit which is low in circuit cost, high in reliability, simple in structure and simple in control strategy. The improved Crowbar circuit meets the requirement of an existing Crowbar circuit for protecting a doubly-fed wind generator and overcomes the defect that in the voltage drop process, low voltage ride through can not be achieved through the existing Crowbar circuit. According to a doubly-fed wind generator low voltage ride through control method, the defect that a Crowbar protection circuit on the rotor side can not provide reactive power support for a power grid is mainly overcome by arranging the Crowbar protection circuit on the stator side. The doubly-fed wind generator low voltage ride through control method is mainly characterized in that control is achieved through rotor exciting voltage when the voltage drop amplitude is smaller than the limit value of rotor exciting voltage control; control is achieved through the combined action of the rotor exciting voltage and the Crowbar protection circuit when the voltage drop amplitude is larger than the limit value of rotor exciting voltage control. When the method is applied, the low voltage ride through capacity can be effectively improved under the condition of the wide-range voltage drop, a doubly-fed wind generator system can be kept connected with the power grid all the time, and stability of the wind generator system is improved.

Description

Based on the double-fed wind power generator low voltage traversing control method that improves Crowbar
Technical field
The invention belongs to wind power generation field, especially relate to a kind of DFIG low voltage crossing control of improved Crowbar circuit.
Background technology
In recent years, along with the development of wind generating technology, the installed capacity of wind power generation is risen year by year, after electrical network breaks down and causes voltage to fall, if wind turbine generator all off-the-line will bring the transient state of electric power system unstable, and may cause part even system paralyse comprehensively.Therefore electric power system has proposed a series of requirement to the operation of wind power plant, comprise electric network fault ride-through capability, be that the grid-connected point voltage of blower fan is while falling, it is grid-connected that blower fan can keep, even provide certain reactive power to recover with support line voltage to electrical network, until line voltage recovers normal, thereby " passing through " this low-voltage time.Along with the raising of wind-powered electricity generation electrical network penetrance, national associated mechanisms has been put into effect standards and norms, requires wind-driven generator must possess low voltage ride-through function, and this makes the low voltage crossing problem of double-fed wind generating become the hot issue of current research.
The grid-connected point voltage of blower fan that electric network fault causes falls the impact that can bring two broad aspect to double-fed wind power generator group: the one, in generator stator and rotor loop, produce overcurrent, and the 2nd, cause the operation of double-fed wind power generator off-grid.Because power grade compared with the converter of the converters in double-fed wind power generator group and total power wind-powered electricity generation unit is less, so will realize double feedback electric engine is protected in voltage falling process.From electrical network, wind-electricity integration directive/guide regulation, in the time that generation voltage falls fault, double feedback electric engine not off-grid moves and provides reactive power support to electrical network.So low voltage crossing problem is the significant challenge of double-fed wind power generator group design control technology, be directly connected to the stability of the electric power system under wind-powered electricity generation infiltration.
At present, the research that line voltage is fallen the transient response of DFIG unit under fault and improves its LVRT ability is mainly divided into two aspects: be to seek new control strategy on the one hand, its advantage is not need to increase extra cost, but occur that comparatively serious voltage falls, be difficult to realize low-voltage crossing by the improvement of control strategy merely; Another aspect is the method that increases hardware device, increases hardware device and not only makes the cost of wind power equipment increase, and make to control more complicated.The control method that does not increase additional hardware proposing is at present a lot, but all cannot reach the effect of practical application.And the method for additional firmware is mainly in double fed electric machine rotor side configuration Crowbar protective circuit.
At present; rotor-side configuration Crowbar protective circuit is a kind of more conventional low voltage traversing control method; the method is in the time of electric network fault; by Crowbar resistance short circuit; the field power supply of excision generator amature; thereby release energy and reduce the overcurrent of rotor loop by rotor by-pass protective resistance, protection motor.But after Crowbar circuit short circuit, double feedback electric engine is equivalent to common induction generator operation.While operation due to induction machine, can absorb from electrical network idle, be unfavorable for that electric network fault recovers, when serious, can cause off-grid operation, therefore the system power that generator cannot participate in failure process regulates, cannot meet the requirement of grid operation codes to reactive power, unfavorable to the Network Voltage Stability in transient process, make it be difficult to meet increasingly harsh wind-electricity integration directive/guide.
Summary of the invention
The present invention is for avoiding the existing deficiency of above-mentioned prior art, provides the double-fed wind generator that a kind of cost is low, simple in structure, reliability is high improved Crowbar protective circuit.Crowbar circuit is in the past by realizing the effect of the large electric current of restriction, protection exciter converter at rotor-side short circuit bypass resistance; improved Crowbar circuit is that tandem electric inductance reduces transient current in stator loop, not only meets the requirement of the protection to double feedback electric engine but also meet the requirement that electrical network is provided to reactive power support.
Object of the present invention can adopt following technical scheme to be realized:
The invention provides the improved Crowbar protective circuit of a kind of double-fed wind generating, it is to be arranged on stator side that Crowbar circuit is in the past mounted in the improved Crowbar circuit of rotor-side; Crowbar circuit is in the past to be to realize current-limiting protection motor by tandem electric inductance by the realization of resistance short circuit to the improved Crowbar circuit of the protection of double feedback electric engine.
The invention provides the improved Crowbar protective circuit of a kind of double-fed wind generating, formed by control switch K and protection inductance.
To the following three kinds of components of the known existence of expression parsing of electric current in voltage falling process: harmonic component, fundametal compoment and DC component.Because DC component is very little, in the time of restrict rotor electric current, can ignore, in two kinds of alternating current components, the amplitude of harmonic component and fundametal compoment is very large, and in two kinds of alternating current components, the size of amplitude all depends on the parameter of motor, the exciting voltage of running status and rotor.Wherein harmonic component can affect the quality of electrical network electric energy, makes electrical network quality of power supply variation, therefore the impulse current harmonic carcellation when controlling the exciting voltage of rotor can deboost fall in the time that voltage falling is to reach the not object of off-grid operation of wind-driven generator.
Detect in real time double feedback electric engine site place line voltage by checkout gear.
By the K switch operating value comparison of the above-mentioned line voltage detecting and setting, in the time detecting that the grid-connected point voltage of double-fed wind power generator group falls amplitude and is less than K switch operating value and is the limiting value of rotor excited voltage control strategy, only need to control a rotor excited voltage and realize low voltage crossing.
In the time detecting that the grid-connected point voltage of double-fed wind power generator group falls amplitude and is greater than K switch operating value and is the limiting value of rotor excited voltage control strategy, by control circuit control switch K closure, the improved Crowbar circuit of double-fed wind power generator group will put into operation and realize low voltage crossing by controlling rotor excited voltage simultaneously.
When detecting that the grid-connected point voltage of double-fed wind power generator group falls while being 0, the improved Crowbar circuit of double-fed wind power generator group will put into operation, only need an improved Crowbar circuit just can realize short-circuit protection.
Between the fault emergence period, when after described improved Crowbar circuit puts into operation, grid-connected point voltage is less than Crowbar protection action threshold value, described improved Crowbar circuit is out of service.
The beneficial effect of the invention embodies as follows.
1, the improved Crowbar of double feedback electric engine has overcome the deficiency of rotor-side Crowbar circuit, and can realize double-fed wind power generator provides reactive power to help electric network fault to recover to realize low voltage crossing to electrical network in the time that voltage falls.
2, the improved Crowbar of double feedback electric engine protection has realized original Crowbar and can in the time being short-circuited fault, realize the effect of short-circuit protection.
3, the improved Crowbar protective circuit of the present invention cost is low, reliability is high, simple in structure, control strategy is simple, can be widely used in the low voltage crossing of double-feedback aerogenerator.
Brief description of the drawings
Fig. 1 is the structural representation of the improved Crowbar protective circuit of a kind of double-fed wind generator of the present invention.
Fig. 2 is the partial enlarged drawing of Fig. 1.
The analogous diagram of electric current when Fig. 3 voltage drops into 60%.
When Fig. 4 voltage drops into 60% by the analogous diagram of rotor excited voltage control electric current.
When Fig. 5 voltage drops into 60% by the analogous diagram of rotor excited voltage control active-power P.
When Fig. 6 voltage drops into 60% by the analogous diagram of rotor excited voltage control reactive power Q.
It is that voltage drops into 20% that Fig. 7 voltage drops into the limit that 20%(China voltage falls) analogous diagram of electric current.
When dropping into 20%, Fig. 8 voltage cannot realize the analogous diagram of current limit in 2 (p.u.) by rotor excited voltage merely.
Rotor excited voltage and the coefficient analogous diagram of Crowbar circuit when Fig. 9 voltage drops into 20%.
The analogous diagram of active-power P after rotor excited voltage and the acting in conjunction of Crowbar circuit when Figure 10 voltage drops into 20%.
The analogous diagram of reactive power Q after rotor excited voltage and the acting in conjunction of Crowbar circuit when Figure 11 voltage drops into 20%.
The analogous diagram of electric current when Figure 12 short circuit.
The current simulations figure of Crowbar circuit function when Figure 13 short circuit.
Embodiment
Referring to Fig. 1,2, in the present embodiment, improved Crowbar electricity routing controling switch K and protection inductance form.
Realize improved Crowbar protective circuit function, concrete steps are as follows.
1) by control circuit monitoring double-fed wind power generator site place line voltage.
2) by the K switch operating value comparison of the above-mentioned line voltage detecting and setting, if the amplitude that line voltage falls is less than K switch operating value while being the limiting value of rotor excited voltage control strategy, only realize low voltage crossing by control strategy control rotor excited voltage.
3) in the time that the line voltage monitoring falls amplitude and is greater than K switch operating value and is the limiting value of rotor excited voltage control strategy; disconnect by control unit control switch K; by improved Crowbar inductance access; thereby will be in double feedback electric engine stator loop access protection inductance, install inductance additional simultaneously with the control strategy control rotor excited voltage transient current of decaying by stator.
4) in the time that the line voltage monitoring drops into 0, disconnect by control unit control switch K, by improved Crowbar inductance access stator inductance, make stator loop install inductance additional and realize short-circuit protection.
5) monitored after the magnitude of voltage recovery of electrical network by voltage monitoring unit, by control unit control switch K closure, by by-pass inductor excision, double-fed wind power generator normally moves.
6) through after aforesaid operations, low voltage ride through control system returns to again normal operating state, repeats aforesaid operations when monitoring when line voltage falls next time again.
Fall ruuning situation under failure condition as example taking the typical double-fed wind power generator group of a 1.5MW at voltage, the validity of control method of the present invention is described.

Claims (4)

1. the improved Crowbar protective circuit of double-fed wind generator, by being made up of control switch K and protection inductance.
2. the invention provides the improved Crowbar protective circuit of double-fed wind generator that a kind of cost is low, simple in structure, reliability is high; Crowbar circuit is in the past by realizing the effect of the large electric current of restriction, protection exciter converter at rotor-side short circuit bypass resistance, improved Crowbar circuit is that tandem electric inductance reduces transient current and realizes the protection to double feedback electric engine in stator loop.
3. the improved Crowbar protective circuit of double-fed wind generator described in a claim 1,2 is characterized in that: can realize double-fed wind power generator and in the time that voltage falls, realize the protection to generator and provide reactive power to help electric network fault to recover to realize low voltage crossing to electrical network; In the time being short-circuited fault, realize the short-circuit protection to double feedback electric engine.
4. the control method that the present invention combines by improved Crowbar and rotor excited voltage control realizes voltage while falling low voltage crossing and short-circuit protection, concrete steps are as follows;
1) detect in real time double feedback electric engine site place line voltage by checkout gear;
2) by the K switch operating value comparison of the above-mentioned line voltage detecting and setting, in the time detecting that the grid-connected point voltage of double-fed wind power generator group falls amplitude and is less than K switch operating value and is the limiting value of rotor excited voltage control strategy, only need to control a rotor excited voltage and can realize low voltage crossing;
?3) in the time detecting that the grid-connected point voltage of double-fed wind power generator group falls amplitude and is greater than K switch operating value and is the limiting value of rotor excited voltage control strategy, by control circuit control switch K closure, the improved Crowbar circuit of double-fed wind power generator group will put into operation and realize low voltage crossing by controlling rotor excited voltage simultaneously;
4) when detecting that the grid-connected point voltage of double-fed wind power generator group falls while being 0, the improved Crowbar circuit of double-fed wind power generator will put into operation, realize short-circuit protection by improved Crowbar circuit;
5), between the fault emergence period, when after described improved Crowbar circuit puts into operation, grid-connected point voltage is less than Crowbar protection action threshold value, described improved Crowbar circuit is out of service.
CN201410264872.9A 2014-06-16 2014-06-16 Doubly-fed wind generator low voltage ride through control method based on improved Crowbar CN104022529A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104795840A (en) * 2015-04-24 2015-07-22 国家电网公司 System and method for improving low voltage ride through capability of wind power generation system
CN108711883A (en) * 2018-05-24 2018-10-26 国家电网公司 Coordinate fault traversing method of the wind power plant through flexible DC power transmission grid-connected system
CN109444737A (en) * 2018-09-11 2019-03-08 昆明理工大学 It is a kind of meter and crow bar operating time of protection double-fed blower three short circuit current analytic method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101383576A (en) * 2008-10-28 2009-03-11 华北电力大学(保定) Method for large-sized wind-driven generator group to get through low voltage failure of electric network
US20120112708A1 (en) * 2010-11-04 2012-05-10 Korea Electrotechnology Research Institute Control Device for Doubly-Fed Induction Generator in Which Feedback Linearization Method is Embedded
CN102646991A (en) * 2012-04-12 2012-08-22 山东电力研究院 Low-voltage ride-through switch and dynamic resistor for double-fed type wind driven generator set

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101383576A (en) * 2008-10-28 2009-03-11 华北电力大学(保定) Method for large-sized wind-driven generator group to get through low voltage failure of electric network
US20120112708A1 (en) * 2010-11-04 2012-05-10 Korea Electrotechnology Research Institute Control Device for Doubly-Fed Induction Generator in Which Feedback Linearization Method is Embedded
CN102646991A (en) * 2012-04-12 2012-08-22 山东电力研究院 Low-voltage ride-through switch and dynamic resistor for double-fed type wind driven generator set

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104795840A (en) * 2015-04-24 2015-07-22 国家电网公司 System and method for improving low voltage ride through capability of wind power generation system
CN108711883A (en) * 2018-05-24 2018-10-26 国家电网公司 Coordinate fault traversing method of the wind power plant through flexible DC power transmission grid-connected system
CN108711883B (en) * 2018-05-24 2020-07-03 国家电网公司 Coordinated fault ride-through method for wind power plant through flexible direct current power transmission grid-connected system
CN109444737A (en) * 2018-09-11 2019-03-08 昆明理工大学 It is a kind of meter and crow bar operating time of protection double-fed blower three short circuit current analytic method

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