CN203574375U - Doubly-fed asynchronous wind generating set low voltage cross-over device based on DVR - Google Patents

Abstract

The utility model relates to a doubly-fed asynchronous wind generating set low voltage cross-over device based on a DVR. The doubly-fed asynchronous wind generating set low voltage cross-over device based on the DVR is characterized by comprising a doubly-fed asynchronous wind generating set and a DVR dynamic voltage recovery device. The doubly-fed asynchronous wind generating set low voltage cross-over device based on the DVR is advantaged in that low voltage cross-over capability of a DFIG set is improved, and voltage fluctuation of a stator can further be reduced or even eliminated by the dynamic voltage recovery device and an injection transformer.

Description

Dual-feed asynchronous wind power generator group low voltage ride through device based on DVR

(1) technical field:

The utility model relates to a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR, belongs to electric and electronic technical field.

(2) background technology:

The energy is one of three large bases that form objective world, and the mankind find continuable energy road, and developing new and renewable sources of energy is the emphasis that improves energy resource system.Wind energy is the mobile kinetic energy producing of earth surface large quantity of air.Because ground is subject to after solar irradiation temperature Change different different with the content of water in air steam, thereby cause the difference of various places air pressure everywhere, pressure-air is mobile to low pressure area in the horizontal direction.Wind power generation is regenerative resource, and very environmental protection is very clean.Wind energy is as clean energy source, and its facility is increasingly progressive, and a large amount of production reduces costs, and in suitable place, cost of wind power generation is lower than other generator.Along with the rapid growth of wind power generation in worldwide, installed capacity of wind-driven power shared proportion in electric power system improves fast, make between large-scale wind electricity unit and partial electric grid influence each other also increasing.In order to ensure the security of operation of electric power system, to wind-powered electricity generation, access has proposed more and more stricter requirement to the power grid operation business of countries in the world, is wherein concerned by people most, is also low voltage crossing (LVRT) ability that the most implacable requirement is wind-powered electricity generation unit.

In various types of wind turbine generator, the advantages such as speed variant frequency constant dual feedback asynchronous generator (DFIG) can independent regulation with its speed-regulating range width, meritorious and reactive power and required exciter converter capacity is less, become at present international mainstream wind-powered electricity generation type, occupied most market shares.But due to DFIG stator direct grid-connected, be easy to be subject to the impact of various electric network faults, therefore, when electrical network falls, there is the shortcomings such as reaction speed is slow, low voltage ride-through capability is not enough.And dynamic voltage compensator (dynamicvoltagerestore is called for short DVR) is as the most advanced at present compensation equipment, can in ms level, make compensating movement, make voltage stabilization in falling process.For these reasons, the utility model adds dynamic voltage compensator can effectively solve the problem of current existence in dual-feed asynchronous wind power generator group.

Except low voltage crossing (LVRT) ability, current electrical network standard is passed through (Highvoltageridethrough to the high pressure of wind-powered electricity generation unit, HVRT) ability has also proposed requirement, and for example Australian electrical network code requirement wind-powered electricity generation unit has the ability that maintains 60ms uninterrupted operation when line voltage rises sharply to 1.3pu.Different from LVRT, Crowbar technology and the DC chopper circuit of current extensive employing are inoperative to HVRT, only have the stable HVRT that could realize of the dual-feed asynchronous wind power generator group (DFIG) of maintenance stator voltage to move.The scheme of current main employing has DVR and dynamic reactive compensator (Staticcompensator, STATCOM).With respect to DVR, STATCOM need to absorb very large reactive power just can maintain the stable of DFIG stator voltage, higher to power device capacity requirement: and in the asymmetric situation of line voltage STATCOM application not as DVR flexible, therefore should preferentially select DVR to realize the HVRT operation of DFIG.

(3) utility model content:

The purpose of this utility model is to provide a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR, in the normal operation of electrical network, be can detection system voltage fluctuation, the in the situation that of electrical network generation low voltage failure, system can be exported bucking voltage falling with compensation network voltage fast, make the voltage of inverter output end mouth substantially keep constant, thereby make dual-feed asynchronous wind power generator group there is the ability of low voltage crossing, it is by appropriate design circuit structure, then utilize the own characteristic of dynamic voltage compensator to reduce the reaction time that voltage falls, improve low voltage ride-through capability, and simple in structure, easy to operate.

The technical solution of the utility model is: a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR, is characterized in that it comprises double-fed asynchronous wind-powered electricity generation unit and DVR dynamic electric voltage recovery device; Wherein said double-fed asynchronous wind-powered electricity generation unit directly connects electrical network; The input of described DVR dynamic electric voltage recovery device gathers the voltage of network system side, and its output connects the output of double-fed asynchronous wind-powered electricity generation unit and the input of electrical network.

Described double-fed asynchronous wind-powered electricity generation unit is comprised of wind turbine generator and current transformer; Described wind turbine generator directly connects electrical network, gathers line voltage as stator voltage; Gather current transformer voltage as rotor voltage; Described current transformer comprises GSC net side converter and RSC rotor-side converter.

Described DVR dynamic electric voltage recovery device is comprised of controller unit, energy storage unit, shunt capacitor, inverter circuit unit, filter circuit unit, series transformer and rectifier; Described DVR dynamic electric voltage recovery device is by filter circuit unit and series transformer access electrical network; The input of described energy storage unit is connected with the output of rectifier and controller unit, and its output is connected with inverter circuit unit by shunt capacitor; The input of described rectifier unit gathers the voltage and current signal of electrical network.

What described controller unit adopted is UC3942A chip.

The energy-storage units of described DVR dynamic electric voltage recovery device is provided with the energy storage for power supply part of five series connection, and each part consists of a H bridge inverter and an energy-storage travelling wave tube.

Method of work of the present utility model: (1) is detected voltage fluctuation and made reasonable action; (2) dynamic electric voltage recovery device acknowledge(ment) signal make compensation; (3) bucking voltage is injected to circuit, stablize double-fed asynchronous generator fan-out capability.

Operation principle of the present utility model:

(1) voltage falls compensation

When line voltage is normal, DVR does not work, and between electrical network and DFIG stator, by the secondary of injection transformer, is connected.Because the leakage impedance of injection transformer is very little, line voltage is equated substantially with stator voltage.When line voltage fault causes DFIG stator voltage amplitude to depart from normal value, DVR starts working, and adopts feedfoward control principle, output suitable voltage, the former limit output bucking voltage through LC filter to injection transformer.Original edge voltage is passed to after injection transformer secondary via Transformer Winding coupling, and the stator voltage that makes DFIG is line voltage and injection transformer secondary voltage sum,

U _s+U _g＝U _com

U in formula _comfor the bucking voltage of DVR output, by changing U _comit is the stator voltage of adjustable dual-feed asynchronous wind power generator group.

What its controller unit adopted is UC3942A chip, as shown in Figure 6, is high-performance fixed frequency current mode controller.For only needing minimum original paper, designer just can obtain the solution of top gain.These integrated circuits have fine-tuning oscillator, can carry out accurately Duty ratio control, plus and blowup.Be characterized in that starting current is low, internal reference voltage stabilization, stronger load individual features, automatically negative feedback compensating circuit.Can provide stable control technology for motor.

If also contain harmonic component in same line voltage, by DVR, can compensate harmonic voltage equally, guarantee the symmetrical and sinusoidal of dual-feed asynchronous wind power generator group stator voltage, keep total meritorious, reactive power that DFIG unit sends to stablize, the electric current of whole unit output is symmetrical and sinusoidal.

DVR dynamic voltage compensator is connected on the system side of wind power system by injection transformer.When system generation voltage falls, control unit sends instruction to inverter, makes it produce bucking voltage by inverter, then through output filter, goes out harmonic wave, moreover compensates by series transformer entry-line.When system is during in normal operation, DVR compensation side disconnects, and rectification side is opened, and system is to DVR makeup energy.

(2) voltage fluctuation detects

Common three-phase power supply system represents with abc coordinate system, and this coordinate is actionless in space.Dq coordinate is by space, two phase coordinates with generator synchronous rotary form, and the conversion that is tied to dq coordinate system from abc coordinate is called Park Transformation (dq conversion).

Consider that virtual voltage exists distortion and uneven, makes the expression formula of abc three-phase voltage be:

$\left\{\begin{array}{c}{U}_a=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\sqrt{2}{U}_{1i}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{1i})+\\ \underset{i=1}{\overset{n}{\mathrm{\Σ}}}\sqrt{2}{U}_{2i}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{2i})\\ U_b=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\sqrt{2}{U}_{1i}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{1i}-\frac{2}{3}\mathrm{\π})+\\ \underset{i=1}{\overset{n}{\mathrm{\Σ}}}\sqrt{2}{U}_{2i}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{2i}+\frac{2}{3}\mathrm{\π})\\ U_c=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\sqrt{2}{U}_{1i}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{1i}+\frac{2}{3}\mathrm{\π})+\\ \underset{i=1}{\overset{n}{\mathrm{\Σ}}}\sqrt{2}{U}_{2i}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{2i}-\frac{2}{3}\mathrm{\π})\end{array}\right.$

U in formula _1ifor positive sequence i subharmonic effective value; U _2ifor negative phase-sequence i subharmonic effective value; θ _1ifor positive sequence i subharmonic initial phase angle; θ _2ifor negative phase-sequence i subharmonic initial phase angle.

The relational expression that abc three-phase voltage is transformed to dq coordinate is:

$\begin{array}{c}\left[\begin{array}{c}{U}_d\\ U_q\end{array}\right]=C\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right]=\\ \sqrt{\frac{2}{3}}\left[\begin{array}{ccc}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{11})& \sin (\mathrm{\ωt}-\frac{2}{3}\mathrm{\π}+{\mathrm{\θ}}_{11})& \sin (\mathrm{\ωt}+\frac{2}{3}\mathrm{\π}+{\mathrm{\θ}}_{11})\\ -\cos (\mathrm{\ωt}+{\mathrm{\θ}}_{11})& -\cos (\mathrm{\ωt}-\frac{2}{3}\mathrm{\π}+{\mathrm{\θ}}_{11})& -\cos (\mathrm{\ωt}+\frac{2}{3}\mathrm{\π}+{\mathrm{\θ}}_{11})\end{array}\right]\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right]\end{array}$

In formula, U _dfor d shaft voltage component; U _qfor q shaft voltage component.Sin (ω t+ θ in transformation matrix C ₁₁), cos (ω t+ θ ₁₁) be and the synchronous cosine and sine signal of a phase voltage.Two formulas are combined:

$\begin{array}{c}\left[\begin{array}{c}{U}_d\\ U_q\end{array}\right]=\sqrt{3}{U}_{11}\left[\begin{array}{c}1\\ 0\end{array}\right]+\\ \frac{\sqrt{3}}{2}{U}_{1i}\left[\begin{array}{c}\underset{i=2}{\overset{n}{\mathrm{\Σ}}}\cos [\mathrm{\ω}(i-1)t+d_{1i}]\\ \underset{i=2}{\overset{n}{\mathrm{\Σ}}}\sin [\mathrm{\ω}(i-1)t+d_{1i}]\end{array}\right]+\\ \frac{\sqrt{3}}{2}{U}_{2i}\left[\begin{array}{c}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}-\cos [\mathrm{\ω}(i+1)t+d_{2i}]\\ \underset{i=1}{\overset{n}{\mathrm{\Σ}}}-\sin [\mathrm{\ω}(i+1)t+d_{2i}]\end{array}\right]\end{array}$

From above formula, abc three-phase voltage is after dq conversion, and positive sequence fundametal compoment becomes DC component, and positive sequence nth harmonic component becomes n-1 order harmonic components, and negative phase-sequence nth harmonic component becomes n+1 order harmonic components.U _d, U _qthrough all harmonic components of low pass filter filtering, can obtain:

$\left[\begin{array}{c}{U}_d\\ U_q\end{array}\right]=\sqrt{3}{U}_{11}\left[\begin{array}{c}1\\ 0\end{array}\right]$

By above formula, can instantaneously be tried to achieve the effective value of positive sequence fundamental voltage.But because actual voltage falls the single-phase event that mostly is, and much voltage falls the reduction that not only causes points of common connection voltage magnitude, also can cause the saltus step of voltage-phase.Suppose that a phase voltage falls and follow the phase hit of α angle, in first formula, the positive sequence fundametal compoment of a phase becomes $\sqrt{2}{U}_{11}\sin (\mathrm{\ωt}+{\mathrm{\θ}}_{11}+\mathrm{\α}),$ Three-phase voltage to structure carries out dq conversion according to second formula, and the result after conversion, after low pass filter extracts, can obtain:

$\left[\begin{array}{c}{U}_d\\ U_q\end{array}\right]=\sqrt{3}{U}_{11}\left[\begin{array}{c}\cos \mathrm{\α}\\ -\sin \mathrm{\α}\end{array}\right]$

Due to U _d, U _qfor process measurement and by the known U calculating _du _qamount, so can obtain effective value and the phase hit angle α of a phase positive sequence first-harmonic from above formula, is respectively:

$\left\{\begin{array}{c}{U}_{11}=\frac{\sqrt{3}}{3}\sqrt{{\mathrm{<figure-callout\; id="2"\; label="U\; d"\; filenames="HDA0000416407720000032.png"\; state="\{\{state\}\}">U</figure-callout>}}_d^{}+{\mathrm{<figure-callout\; id="2"\; label="U\; q"\; filenames="HDA0000416407720000032.png"\; state="\{\{state\}\}">U</figure-callout>}}_q^{}}\\ \mathrm{\&alpha;}=\mathrm{arctg}\left|\frac{U_q}{U_d}\right|\end{array}\right.$

By above-mentioned two formulas, when fluctuation occurs in good time voltage, just can detect.

From above analysis; adopt DVR can fundamentally solve voltage afterwards and fall the adverse effect to dual-feed asynchronous wind power generator group; the operation control of dual-feed asynchronous wind power generator group self is become simply, even can save the protective device of the serious electric network fault of various replies.Monitoring and the detection that under blower fan normal operating condition, can also carry out voltage to it, facilitate actual motion.

Superiority of the present utility model is: when electrical network breaks down, dynamic electric voltage recovery device can serve as power supply in short-term, to dual-feed asynchronous wind power generator group, provides meritorious and idle.Improved the low voltage ride-through capability of DFIG unit, dynamic electric voltage recovery device and injection transformer can also reduce even to eliminate the fluctuation of stator voltage simultaneously.If also contain harmonic component in same line voltage, by DVR, can compensate harmonic voltage equally, guarantee the symmetrical and sinusoidal of DFIG generator unit voltage, keep total meritorious, reactive power that DFIG unit sends to stablize, the electric current of whole unit output is symmetrical and sinusoidal.

(4) accompanying drawing explanation:

Fig. 1 is the overall structure schematic diagram of the related a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR of the utility model.

Fig. 2 be the related a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR of the utility model in double-fed asynchronous wind-powered electricity generation unit structural representation.

Fig. 3 is the middle DVR dynamic electric voltage recovery device structural representation of the related a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR of the utility model.

Fig. 4 is middle DVR dynamic electric voltage recovery device energy-storage travelling wave tube (the five level cascades) structure chart of the related a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR of the utility model.

Fig. 5 is the circuit structure diagram of the rectifier of the middle DVR dynamic electric voltage recovery device of the related a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR of the utility model.

Fig. 6 is the middle UC3942A chip simplified block diagram of the related a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR of the utility model.

(5) embodiment:

Embodiment: a kind of dual-feed asynchronous wind power generator group low voltage ride through device (see figure 1) based on DVR, is characterized in that it comprises double-fed asynchronous wind-powered electricity generation unit and DVR dynamic electric voltage recovery device; Wherein said double-fed asynchronous wind-powered electricity generation unit directly connects electrical network; The input of described DVR dynamic electric voltage recovery device gathers the voltage of network system side, and its output connects the output of double-fed asynchronous wind-powered electricity generation unit and the input of electrical network.

Described double-fed asynchronous wind-powered electricity generation unit (see figure 2) is comprised of wind turbine generator and current transformer; Described wind turbine generator directly connects electrical network, gathers line voltage as stator voltage; Gather current transformer voltage as rotor voltage; Described current transformer comprises GSC net side converter and RSC rotor-side converter.

Described DVR dynamic electric voltage recovery device (see figure 3) is comprised of controller unit, energy storage unit, shunt capacitor, inverter circuit unit, filter circuit unit, series transformer and rectifier; Described DVR dynamic electric voltage recovery device is by filter circuit unit and series transformer access electrical network; The input of described energy storage unit is connected with the output of rectifier and controller unit, and its output is connected with inverter circuit unit by shunt capacitor; The input of described rectifier unit gathers the voltage and current signal of electrical network.

What described controller unit adopted is UC3942A chip (see figure 6).

The energy-storage units of described DVR dynamic electric voltage recovery device is provided with the energy storage for power supply part (see figure 4) of five series connection, and each part consists of a H bridge inverter and an energy-storage travelling wave tube.

Claims (5)

1. the dual-feed asynchronous wind power generator group low voltage ride through device based on DVR, is characterized in that it comprises double-fed asynchronous wind-powered electricity generation unit and DVR dynamic electric voltage recovery device; Wherein said double-fed asynchronous wind-powered electricity generation unit directly connects electrical network; The input of described DVR dynamic electric voltage recovery device gathers the voltage of network system side, and its output connects the output of double-fed asynchronous wind-powered electricity generation unit and the input of electrical network.

2. a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR according to claim 1, is characterized in that stating double-fed asynchronous wind-powered electricity generation unit and is comprised of wind turbine generator and current transformer; Described wind turbine generator directly connects electrical network, gathers line voltage as stator voltage; Gather current transformer voltage as rotor voltage; Described current transformer comprises GSC net side converter and RSC rotor-side converter.

3. a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR according to claim 1, is characterized in that described DVR dynamic electric voltage recovery device is comprised of controller unit, energy storage unit, shunt capacitor, inverter circuit unit, filter circuit unit, series transformer and rectifier; Described DVR dynamic electric voltage recovery device is by filter circuit unit and series transformer access electrical network; The input of described energy storage unit is connected with the output of rectifier and controller unit, and its output is connected with inverter circuit unit by shunt capacitor; The input of described rectifier unit gathers the voltage and current signal of electrical network.

4. a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR according to claim 3, what it is characterized in that described controller unit adopts is UC3942A chip.

5. a kind of dual-feed asynchronous wind power generator group low voltage ride through device based on DVR according to claim 3, it is characterized in that the energy storage unit of described DVR dynamic electric voltage recovery device is provided with the energy storage for power supply part of five series connection, each part consists of a H bridge inverter and an energy-storage travelling wave tube.

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