CN103219736A - Control method of suppressing double-frequency fluctuation on direct current side of permanent magnetic direct-drive wind power generation system through flywheel energy-storing unit - Google Patents

Abstract

Provided is a control method of suppressing double-frequency fluctuation on a direct current side of a permanent magnetic direct-drive wind power generation system through a flywheel energy-storing unit. Power on two sides of a middle direct current link of the permanent magnetic direct-drive wind power generation system in unsymmetrical faults of a power grid is calculated, a control command of flywheel energy-storing motor power is obtained, and a given current command of a q shaft of a flywheel motor is further calculated. A flywheel energy-storing unit is controlled to absorb or release power to achieve fluctuation power compensation of a direct current capacitor, and suppression of the double-frequency fluctuation of voltage on the direct current side is achieved. By means of calculation of the power on the two sides of the middle direct current link of the permanent magnetic direct-drive wind power generation system in the unsymmetrical faults of the power grid, the control command of the flywheel energy-storing motor power is obtained, the given current command of the q shaft of the flywheel motor is further calculated, the flywheel energy-storing unit is controlled to absorb or release the power to achieve the fluctuation power compensation of the direct current capacitor, and therefore the suppression of the double-frequency fluctuation of the voltage on the direct current side is achieved.

Description

A kind of flywheel energy storage unit suppresses the control method of permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication fluctuation

Technical field

The present invention relates to wind generator system control field, especially during electrical network unsymmetrical short-circuit fault, utilize the flywheel energy storage unit to suppress the control method of permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication fluctuation.

Background technology

Dc bus plays crucial effects for the permanent magnet direct-drive wind generator system, and the providing of stable DC voltage of the conveying of magneto alternator active power and two pwm converters is being provided.Along with improving constantly of direct-drive permanent magnetism synchronous wind generating technology, the stable operation of dc-link capacitance under improper situation is subjected to the extensive concern of Chinese scholars.Especially when electrical network generation unbalanced fault, all there are the positive-negative sequence component in line voltage and current on line side, its interaction and cause permanent magnet direct-drive wind power system grid side power 2 times of power frequency fluctuations to occur, this wave component will further cause DC bus-bar voltage 2 times of power frequency fluctuations largely, bring very big threat for the safe and stable operation of dc-link capacitance and even whole system.Domestic existing scholar has launched correlative study with regard to how suppressing the permanent magnet direct-driving aerogenerator group at the asymmetric intentional 2 times of power frequency fluctuations of DC bus-bar voltage down of electrical network at present, discloses following document:

Meritorious and idle control method for coordinating when (1) permanent magnet direct-drive wind power system low-voltage is passed through. Chinese invention patent, application number: 201210166079.6

(2) operation and the control of direct-driving permanent magnetic wind generator system net side converter under the asymmetric electric network fault. electrotechnics journal, 2011,26 (2): 173-180.

Document (1) proposes under electric network fault permanent magnet direct-drive wind generator system pusher side converter using based on the direct voltage control model of rotor energy storage, by discharging or storing the fluctuation that magneto alternator rotor kinetic energy suppresses DC bus-bar voltage, improved the low voltage ride-through capability of permanent magnetism direct drive wind group of motors.This method is come the pulsating power of balance DC side by the absorption and the release of rotor kinetic energy, makes rotor bear the torque of pulsation, and this will influence long-term stability operation of parts such as rotor bearing.

Document (2) has been analyzed the mechanism of direct-drive permanent magnet synchronous aerogenerator group DC bus-bar voltage fluctuation under the unbalanced source voltage, has proposed a kind ofly to be delivered to the fluctuation of grid power 2 frequencys multiplication and further to suppress the purpose that dc voltage 2 frequencys multiplication fluctuate by eliminating the grid side converter.But when electrical network generation degree of depth unbalanced fault, line voltage occurs uneven largely, this method will take the 2 frequencys multiplication fluctuation that the most of current capacity of net side suppresses direct voltage, and this can't satisfy the new guide rule that is incorporated into the power networks proposes to provide to electrical network the reactive power support to the wind-powered electricity generation unit new demand.

Summary of the invention

At above-mentioned technical problem, the invention provides the control method that a kind of flywheel energy storage unit suppresses the fluctuation of permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication, this method adopts flywheel energy storage unit to absorb or delivered power, realizes the fluctuating power compensation of dc capacitor.

To achieve these goals, the technical solution used in the present invention is as follows:

A kind of flywheel energy storage unit suppresses the control method of permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication fluctuation, it is characterized in that, permanent magnet direct-driving aerogenerator system intermediate dc link both sides power under the electrical network unbalanced fault is calculated, obtain flywheel energy storage power of motor control command, and then calculate the given instruction of fly-wheel motor q shaft current, control flywheel energy storage unit absorbs or delivered power is realized the fluctuating power of dc capacitor is compensated, and realizes the inhibition to the fluctuation of dc voltage 2 frequencys multiplication.

The described flywheel energy storage power of motor control command of obtaining, calculate the given instruction of fly-wheel motor q shaft current, obtain the switching signal of control fly-wheel motor side converter, unit absorption of realization control flywheel energy storage or delivered power are realized the concrete steps of the fluctuating power compensation of dc capacitor as follows:

(1) gather electrical network three-phase voltage signal and three-phase current signal, this three-phase voltage signal and three-phase current signal carried out positive-negative sequence separate, be converted to the voltage signal of the synchronous rotary axis of forward:

The voltage signal of reverse sync rotary axis:

The current signal of the synchronous rotary axis of forward:

The voltage signal of reverse sync rotary axis:

(2) calculate grid side power averaging component P by the grid side converter power matrix _{G_av}, Q _{G_av}And just, cosine component P _{G_sin2}, P _{G_cos2}, Q _{G_sin2}, Q _{G_cos2}, computing formula is:

$\left[\begin{array}{c}{P}_{g\_\mathrm{av}}\\ Q_{g\_\mathrm{av}}\\ P_{g\_\cos 2}\\ P_{g\_\sin 2}\\ Q_{g\_\cos 2}\\ Q_{g\_\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HDA00002909393100013.png,HDA00002909393100031.png"\; state="\{\{state\}\}">sin</figure-callout>}2}\end{array}\right]=\left[\begin{array}{cccc}{u}_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}& u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}-}^{-}\\ u_{\mathrm{gq}+}^{+}& -u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}\\ u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}-}^{-}& u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}\\ u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}& {-u}_{\mathrm{gq}+}^{+}& u_{\mathrm{gd}+}^{+}\\ u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}+}^{+}& -u_{\mathrm{gd}+}^{+}\\ -u_{\mathrm{gd}-}^{-}& -u_{\mathrm{gq}-}^{-}& u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{i}_{\mathrm{gd}+}^{+}\\ i_{\mathrm{gq}+}^{+}\\ i_{\mathrm{gd}-}^{-}\\ i_{\mathrm{gq}-}^{-}\end{array}\right]$

(3), calculate inlet wire reactor instantaneous active power average value P according to step (1) _{GL_av}With reactive power mean value Q _{GL_av}And the sinusoidal component P of this inlet wire reactor instantaneous active power mean value _{GL_sin2}With cosine component P _{GL_cos2}, computing formula is as follows:

$\left\{\begin{array}{c}{P}_{\mathrm{gL}\_\mathrm{av}}=R_g(i_{\mathrm{gd}+}^{+2}+i_{\mathrm{gq}+}^{+2}+i_{\mathrm{gd}-}^{-2}+i_{\mathrm{gq}-}^{-2})\\ Q_{\mathrm{gL}\_\mathrm{av}}=\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+2}+i_{\mathrm{gq}+}^{+2}-i_{\mathrm{gd}-}^{-2}-i_{\mathrm{gq}-}^{-2})\\ P_{\mathrm{gL}\_\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA00002909393100013.png,HDA00002909393100031.png"\; state="\{\{state\}\}">cos</figure-callout>}2}=2\&CenterDot;[R_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gd}-}^{-}+i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gq}-}^{-})+\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gq}-}^{-}-i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gd}-}^{-})]\\ P_{\mathrm{gL}\_\sin 2}=2\&CenterDot;[R_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gq}-}^{-}-i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gd}-}^{-})-\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gd}-}^{-}+i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gq}-}^{-})]\end{array}\right.$

(4) calculate grid side converter ac output end mouth performance number, computing formula is as follows:

P _gc=P _g+P _gL

=(P _{g_av}+P _{gL_av})+(P _{g_cos2}+P _{gL_cos2})cos2ωt

+(P _{g_sin2}+P _{gL_sin2})sin2ωt

(5) pusher side converter power output P _sPoor with the grid side converter ac output end mouth performance number of step (4), with this difference as flywheel energy storage unit compensation DC side 2 frequency multiplication fluctuating power set-points;

$\mathrm{\&Delta;}{P}_f^{*}=P_s-P_{\mathrm{gc}}$

(6) with DC side virtual voltage U _DcThe normal voltage default with this DC side Make comparisons, deviation by behind the permagnetic synchronous motor outer voltage pi regulator again with default normal voltage

Multiply each other as flywheel average absorption power:

$P_{f\_\mathrm{av}}^{*}=\left[(K_p+K_i/s)(U_{\mathrm{dc}}^{*}-U_{\mathrm{dc}})\right]U_{\mathrm{dc}}^{*}$

In the formula, K _pAnd K _iProportionality coefficient and the integral coefficient of representing permagnetic synchronous motor outer voltage pi regulator respectively;

(7) according to step (5) and step (6) and motor side converter power output P _s, obtain the instruction of flywheel energy storage system gross power:

$P_f^{*}=P_s+P_{f\_\mathrm{av}}^{*}+\mathrm{\&Delta;}{P}_f^{*}$

(8) according to the resulting flywheel energy storage system gross power instruction of step (7), further obtain the given instruction of permagnetic synchronous motor q shaft current by following formula:

$\left\{\begin{array}{c}{i}_{\mathrm{fd}}^{*}=0\\ i_{\mathrm{fq}}^{*}=\frac{P_f^{*}}{p_f{\mathrm{\&omega;}}_f{\mathrm{\&psi;}}_f}\end{array}\right.$

ω in the formula _fBe permanent-magnetic synchronous motor rotor electric angle speed, ψ _fBe permanent-magnetism synchronous motor permanent magnetic body magnetic linkage, p _fBe the permagnetic synchronous motor number of pole-pairs;

(9) utilize current Hall sensor acquisition permagnetic synchronous motor three-phase current signal, and adopt rotor field-oriented mode, be converted into two-phase rotation dq system of axis current i _Fd, i _FqAnd constitute current inner loop control with the given instruction of step (8) permagnetic synchronous motor dq shaft current, its governing equation is:

$\left\{\begin{array}{c}{u}_{\mathrm{fd}}=(K_{\mathrm{fp}}+K_{\mathrm{fi}}/s)(i_{\mathrm{fd}}^{*}-i_{\mathrm{fd}})-{\mathrm{\&omega;}}_f{L}_f{i}_{\mathrm{fq}}\\ u_{\mathrm{fq}}=(K_{\mathrm{fq}}+K_{\mathrm{fi}}/s)(i_{\mathrm{fq}}^{*}-i_{\mathrm{fq}})+{\mathrm{\&omega;}}_f{L}_f{i}_{\mathrm{fd}}+{\mathrm{\&omega;}}_f{\mathrm{\&Psi;}}_f\end{array}\right.$

In the formula, K _FpAnd K _FiBe respectively the proportionality coefficient and the integral coefficient of the pi regulator of fly-wheel motor side converter control voltage, L _fBe the stator inductance of permagnetic synchronous motor, ω _fBe the rotor electric angle speed of permagnetic synchronous motor, ψ _fPermanent magnet magnetic linkage for permagnetic synchronous motor;

(10) permanent-magnetic synchronous motor stator is controlled voltage u _Fd, u _FqAfter the modulation of space vector pulse width modulation module, can obtain to control the switching signal of fly-wheel motor side converter.

Good effect of the present invention is:

The present invention is by the calculating to permanent magnet direct-driving aerogenerator system intermediate dc link both sides power under the electrical network unbalanced fault, obtain flywheel energy storage power of motor control command, and then calculate the given instruction of fly-wheel motor q shaft current, control flywheel energy storage unit absorbs or delivered power, realization is to the fluctuating power compensation of dc capacitor, thereby realization is to the inhibition of dc voltage 2 frequencys multiplication fluctuation.

Description of drawings

Fig. 1 is the permanent magnet direct-drive wind power system structure chart that the flywheel energy storage unit is installed;

Fig. 2 is the off line side electric current and voltage of an electrical network unbalanced fault positive-negative sequence component computing block diagram;

Fig. 3 is the off line side power component of an electrical network unbalanced fault computing block diagram;

Fig. 4 is the off line side inlet wire of an electrical network unbalanced fault reactor power component computing block diagram;

Fig. 5 is direct current pressure ring controller chassis figure in the electrical network unbalanced fault process;

Fig. 6 is not for adopting the inventive method and the effect contrast figure who adopts the inventive method under the electrical network unsymmetrical short-circuit fault.

Embodiment

Below in conjunction with specific embodiment the present invention is described in further detail.

As shown in Figure 1, on original device basic, increase the flywheel energy storage unit, this flywheel energy storage unit comprises flywheel side converter, permagnetic synchronous motor and the flywheel that is connected with this permagnetic synchronous motor rotating shaft, the flywheel energy storage unit absorbs or delivered power is realized the fluctuating power of dc capacitor is compensated, suppress the fluctuation of permanent magnet direct-drive wind generator system dc voltage 2 frequencys multiplication, for the grid side converter provides the reactive power support to lay the foundation to electrical network during electric network fault to greatest extent, effectively strengthened permanent magnet direct-drive wind power system low-voltage and passed through runnability.

The flywheel energy storage unit suppresses the control method of permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication fluctuation, permanent magnet direct-driving aerogenerator system intermediate dc link both sides power under the electrical network unbalanced fault is calculated, obtain flywheel energy storage power of motor control command, and then calculate the given instruction of fly-wheel motor q shaft current, control flywheel energy storage unit absorbs or delivered power is realized the fluctuating power of dc capacitor is compensated, realization is to the inhibition of dc voltage 2 frequencys multiplication fluctuation, and concrete steps are as follows:

(1) as shown in Figure 2, grid side converter is gathered electrical network three-phase voltage signal and three-phase current signal, this three-phase voltage signal and three-phase current signal are carried out positive-negative sequence separate, and three-phase voltage signal and the three-phase current signal that this separation obtains passed through the voltage signal that grid side converter positive-negative sequence separation module is converted to the synchronous rotary axis of forward respectively:

The voltage signal of reverse sync rotary axis:

The current signal of the synchronous rotary axis of forward:

The voltage signal of reverse sync rotary axis:

(2) by the net side power component computing module of grid side converter, calculate grid side power averaging component P according to the grid side converter power matrix _{G_av}, Q _{G_av}And just, cosine component P _{G_sin2}, P _{G_cos2}, Q _{G_sin2}, Q _{G_cos2}, as shown in Figure 3, its computing formula is:

$\left[\begin{array}{c}{P}_{g\_\mathrm{av}}\\ Q_{g\_\mathrm{av}}\\ P_{g\_\cos 2}\\ P_{g\_\sin 2}\\ Q_{g\_\cos 2}\\ Q_{g\_\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HDA00002909393100013.png,HDA00002909393100031.png"\; state="\{\{state\}\}">sin</figure-callout>}2}\end{array}\right]=\left[\begin{array}{cccc}{u}_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}& u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}-}^{-}\\ u_{\mathrm{gq}+}^{+}& -u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}\\ u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}-}^{-}& u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}\\ u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}& {-u}_{\mathrm{gq}+}^{+}& u_{\mathrm{gd}+}^{+}\\ u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}+}^{+}& -u_{\mathrm{gd}+}^{+}\\ -u_{\mathrm{gd}-}^{-}& -u_{\mathrm{gq}-}^{-}& u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{i}_{\mathrm{gd}+}^{+}\\ i_{\mathrm{gq}+}^{+}\\ i_{\mathrm{gd}-}^{-}\\ i_{\mathrm{gq}-}^{-}\end{array}\right]$

(3) by the inlet wire reactor power component computing module of grid side converter according to step (1), calculate inlet wire reactor instantaneous active power average value P _{GL_av}And the sinusoidal component P of this inlet wire reactor instantaneous active power mean value _{GL_sin2}With cosine component P _{GL_cos2}, as shown in Figure 4, computing formula is as follows:

$\left\{\begin{array}{c}{P}_{\mathrm{gL}\_\mathrm{av}}=R_g(i_{\mathrm{gd}+}^{+2}+i_{\mathrm{gq}+}^{+2}+i_{\mathrm{gd}-}^{-2}+i_{\mathrm{gq}-}^{-2})\\ Q_{\mathrm{gL}\_\mathrm{av}}=\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+2}+i_{\mathrm{gq}+}^{+2}-i_{\mathrm{gd}-}^{-2}-i_{\mathrm{gq}-}^{-2})\\ P_{\mathrm{gL}\_\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA00002909393100013.png,HDA00002909393100031.png"\; state="\{\{state\}\}">cos</figure-callout>}2}=2\&CenterDot;[R_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gd}-}^{-}+i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gq}-}^{-})+\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gq}-}^{-}-i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gd}-}^{-})]\\ P_{\mathrm{gL}\_\sin 2}=2\&CenterDot;[R_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gq}-}^{-}-i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gd}-}^{-})-\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gd}-}^{-}+i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gq}-}^{-})]\end{array}\right.$

(4) calculate grid side converter ac output end mouth performance number, computing formula is as follows:

P _gc=P _g+P _gL

=(P _{g_av}+P _{gL_av})+(P _{g_cos2}+P _{gL_cos2})cos2ωt

+(P _{g_sin2}+P _{gL_sin2})sin2ωt

(5) pusher side converter power output P _sPoor with the grid side converter ac output end mouth performance number of step (4), with this difference as flywheel energy storage unit compensation DC side 2 frequency multiplication fluctuating power set-points;

$\mathrm{\&Delta;}{P}_f^{*}=P_s-P_{\mathrm{gc}}$

(6) as shown in Figure 5, with DC side virtual voltage U _DcThe normal voltage default with this DC side

Make comparisons, deviation by behind the permagnetic synchronous motor outer voltage pi regulator again with default normal voltage Multiply each other as flywheel average absorption power:

$P_{f\_\mathrm{av}}^{*}=\left[(K_p+K_i/s)(U_{\mathrm{dc}}^{*}-U_{\mathrm{dc}})\right]U_{\mathrm{dc}}^{*}$

In the formula, K _pAnd K _iProportionality coefficient and the integral coefficient of representing permagnetic synchronous motor outer voltage pi regulator respectively;

(7) according to step (5) and step (6) and motor side converter power output P _s, obtain the instruction of flywheel energy storage system gross power:

$P_f^{*}=P_s+P_{f\_\mathrm{av}}^{*}+\mathrm{\&Delta;}{P}_f^{*}$

(8) according to the resulting flywheel energy storage system gross power instruction of step (7), further obtain the given instruction of permagnetic synchronous motor q shaft current by following formula:

$\left\{\begin{array}{c}{i}_{\mathrm{fd}}^{*}=0\\ i_{\mathrm{fq}}^{*}=\frac{P_f^{*}}{p_f{\mathrm{\&omega;}}_f{\mathrm{\&psi;}}_f}\end{array}\right.$

ω in the formula _fBe permanent-magnetic synchronous motor rotor electric angle speed, ψ _fBe permanent-magnetism synchronous motor permanent magnetic body magnetic linkage, p _fBe the permagnetic synchronous motor number of pole-pairs;

(9) utilize current Hall sensor acquisition permagnetic synchronous motor three-phase current signal, and adopt rotor field-oriented mode, be converted into two-phase rotation dq system of axis current i _Fd, i _FqAnd constitute current inner loop control with the given instruction of step (8) permagnetic synchronous motor dq shaft current, its governing equation is:

$\left\{\begin{array}{c}{u}_{\mathrm{fd}}=(K_{\mathrm{fp}}+K_{\mathrm{fi}}/s)(i_{\mathrm{fd}}^{*}-i_{\mathrm{fd}})-{\mathrm{\&omega;}}_f{L}_f{i}_{\mathrm{fq}}\\ u_{\mathrm{fq}}=(K_{\mathrm{fq}}+K_{\mathrm{fi}}/s)(i_{\mathrm{fq}}^{*}-i_{\mathrm{fq}})+{\mathrm{\&omega;}}_f{L}_f{i}_{\mathrm{fd}}+{\mathrm{\&omega;}}_f{\mathrm{\&Psi;}}_f\end{array}\right.$

In the formula, K _FpAnd K _FiBe respectively the proportionality coefficient and the integral coefficient of the pi regulator of fly-wheel motor side converter control voltage, L _fBe the stator inductance of permagnetic synchronous motor, ω _fBe the rotor electric angle speed of permagnetic synchronous motor, ψ _fPermanent magnet magnetic linkage for permagnetic synchronous motor;

(10) permanent-magnetic synchronous motor stator is controlled voltage u _Fd, u _FqAfter the modulation of space vector pulse width modulation module, can obtain to control the switching signal of fly-wheel motor side converter.

Adopt this method, when electrical network take place single-phase when dropping into zero, as shown in Figure 6,2 times of power frequency fluctuations largely appear in DC bus-bar voltage, the fluctuation peak-to-peak value is up to 40V, and dc-link capacitance will bear periodically pulsing voltage stress impact largely, be unfavorable for its safe and stable operation.And after adopting method of the present invention, it is little of 6V that 2 times of power frequency fluctuation components of DC bus-bar voltage slow down, and effectively realized suppressing the purpose of 2 times of power frequency fluctuations of direct current chain voltage.

The above embodiment of the present invention only is to be explanation example of the present invention, and is not to be qualification to embodiments of the present invention.For those of ordinary skill in the field, can also make other multi-form variation and changes on the basis of the above description.Here can't give exhaustive to all execution modes.Everyly belong to the row that conspicuous variation that technical scheme of the present invention amplifies out or change still are in protection scope of the present invention.

Claims (2)

1. a flywheel energy storage unit suppresses the control method that permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication fluctuate, it is characterized in that, permanent magnet direct-driving aerogenerator system intermediate dc link both sides power under the electrical network unbalanced fault is calculated, obtain flywheel energy storage power of motor control command, and then calculate the given instruction of fly-wheel motor q shaft current, control flywheel energy storage unit absorbs or delivered power is realized the fluctuating power of dc capacitor is compensated, and realizes the inhibition to the fluctuation of dc voltage 2 frequencys multiplication.

2. flywheel energy storage according to claim 1 unit suppresses the control method of permanent magnet direct-drive wind generator system DC side 2 frequencys multiplication fluctuation, it is characterized in that, the described flywheel energy storage power of motor control command of obtaining, calculate the given instruction of fly-wheel motor q shaft current, obtain the switching signal of control fly-wheel motor side converter, unit absorption of realization control flywheel energy storage or delivered power are realized the concrete steps of the fluctuating power compensation of dc capacitor as follows:

(1) gather electrical network three-phase voltage signal and three-phase current signal, this three-phase voltage signal and three-phase current signal carried out positive-negative sequence separate, be converted to the voltage signal of the synchronous rotary axis of forward: The voltage signal of reverse sync rotary axis:

The current signal of the synchronous rotary axis of forward:

The voltage signal of reverse sync rotary axis:

(2) calculate grid side power averaging component P by the grid side converter power matrix _{G_av}, Q _{G_av}And just, cosine component P _{G_sin2}, P _{G_cos2}, Q _{G_sin2}, Q _{G_cos2}, computing formula is:

$\left[\begin{array}{c}{P}_{g\_\mathrm{av}}\\ Q_{g\_\mathrm{av}}\\ P_{g\_\cos 2}\\ P_{g\_\sin 2}\\ Q_{g\_\cos 2}\\ Q_{g\_\sin 2}\end{array}\right]=\left[\begin{array}{cccc}{u}_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}& u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}-}^{-}\\ u_{\mathrm{gq}+}^{+}& -u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}\\ u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}-}^{-}& u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}\\ u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}& {-u}_{\mathrm{gq}+}^{+}& u_{\mathrm{gd}+}^{+}\\ u_{\mathrm{gq}-}^{-}& -u_{\mathrm{gd}-}^{-}& u_{\mathrm{gq}+}^{+}& -u_{\mathrm{gd}+}^{+}\\ -u_{\mathrm{gd}-}^{-}& -u_{\mathrm{gq}-}^{-}& u_{\mathrm{gd}+}^{+}& u_{\mathrm{gq}+}^{+}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{i}_{\mathrm{gd}+}^{+}\\ i_{\mathrm{gq}+}^{+}\\ i_{\mathrm{gd}-}^{-}\\ i_{\mathrm{gq}-}^{-}\end{array}\right]$

(3), calculate inlet wire reactor instantaneous active power average value P according to step (1) _{GL_av}With reactive power mean value Q _{GL_av}And the sinusoidal component P of this inlet wire reactor instantaneous active power mean value _{GL_sin2}With cosine component P _{GL_cos2}, computing formula is as follows:

$\left\{\begin{array}{c}{P}_{\mathrm{gL}\_\mathrm{av}}=R_g(i_{\mathrm{gd}+}^{+2}+i_{\mathrm{gq}+}^{+2}+i_{\mathrm{gd}-}^{-2}+i_{\mathrm{gq}-}^{-2})\\ Q_{\mathrm{gL}\_\mathrm{av}}=\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+2}+i_{\mathrm{gq}+}^{+2}-i_{\mathrm{gd}-}^{-2}-i_{\mathrm{gq}-}^{-2})\\ P_{\mathrm{gL}\_\cos 2}=2\&CenterDot;[R_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gd}-}^{-}+i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gq}-}^{-})+\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gq}-}^{-}-i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gd}-}^{-})]\\ P_{\mathrm{gL}\_\sin 2}=2\&CenterDot;[R_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gq}-}^{-}-i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gd}-}^{-})-\mathrm{\&omega;}{L}_g(i_{\mathrm{gd}+}^{+}{i}_{\mathrm{gd}-}^{-}+i_{\mathrm{gq}+}^{+}{i}_{\mathrm{gq}-}^{-})]\end{array}\right.$

(4) calculate grid side converter ac output end mouth performance number, computing formula is as follows:

P _gc=P _g+P _gL

=(P _{g_av}+P _{gL_av})+(P _{g_cos2}+P _{gL_cos2})cos2ωt

+(P _{g_sin2}+P _{gL_sin2})sin2ωt

(5) pusher side converter power output P _sPoor with the grid side converter ac output end mouth performance number of step (4), with this difference as flywheel energy storage unit compensation DC side 2 frequency multiplication fluctuating power set-points;

$\mathrm{\&Delta;}{P}_f^{*}=P_s-P_{\mathrm{gc}}$

(6) with DC side virtual voltage U _DcThe normal voltage default with this DC side

Make comparisons, deviation by behind the permagnetic synchronous motor outer voltage pi regulator again with default normal voltage

Multiply each other as flywheel average absorption power:

$P_{f\_\mathrm{av}}^{*}=\left[(K_p+K_i/s)(U_{\mathrm{dc}}^{*}-U_{\mathrm{dc}})\right]U_{\mathrm{dc}}^{*}$

In the formula, K _pAnd K _iProportionality coefficient and the integral coefficient of representing permagnetic synchronous motor outer voltage pi regulator respectively;

(7) according to step (5) and step (6) and motor side converter power output P _s, obtain the instruction of flywheel energy storage system gross power:

$P_f^{*}=P_s+P_{f\_\mathrm{av}}^{*}+\mathrm{\&Delta;}{P}_f^{*}$

(8) according to the resulting flywheel energy storage system gross power instruction of step (7), further obtain the given instruction of permagnetic synchronous motor q shaft current by following formula:

$\left\{\begin{array}{c}{i}_{\mathrm{fd}}^{*}=0\\ i_{\mathrm{fq}}^{*}=\frac{P_f^{*}}{p_f{\mathrm{\&omega;}}_f{\mathrm{\&psi;}}_f}\end{array}\right.$

ω in the formula _fBe permanent-magnetic synchronous motor rotor electric angle speed, ψ _fBe permanent-magnetism synchronous motor permanent magnetic body magnetic linkage, p _fBe the permagnetic synchronous motor number of pole-pairs;

(9) utilize current Hall sensor acquisition permagnetic synchronous motor three-phase current signal, and adopt rotor field-oriented mode, be converted into two-phase rotation dq system of axis current i _Fd, i _FqAnd constitute current inner loop control with the given instruction of step (8) permagnetic synchronous motor dq shaft current, its governing equation is:

$\left\{\begin{array}{c}{u}_{\mathrm{fd}}=(K_{\mathrm{fp}}+K_{\mathrm{fi}}/s)(i_{\mathrm{fd}}^{*}-i_{\mathrm{fd}})-{\mathrm{\&omega;}}_f{L}_f{i}_{\mathrm{fq}}\\ u_{\mathrm{fq}}=(K_{\mathrm{fq}}+K_{\mathrm{fi}}/s)(i_{\mathrm{fq}}^{*}-i_{\mathrm{fq}})+{\mathrm{\&omega;}}_f{L}_f{i}_{\mathrm{fd}}+{\mathrm{\&omega;}}_f{\mathrm{\&Psi;}}_f\end{array}\right.$

In the formula, K _FpAnd K _FiBe respectively the proportionality coefficient and the integral coefficient of the pi regulator of fly-wheel motor side converter control voltage, L _fBe the stator inductance of permagnetic synchronous motor, ω _fBe the rotor electric angle speed of permagnetic synchronous motor, ψ _fPermanent magnet magnetic linkage for permagnetic synchronous motor;

(10) permanent-magnetic synchronous motor stator is controlled voltage u _Fd, u _FqAfter the modulation of space vector pulse width modulation module, can obtain to control the switching signal of fly-wheel motor side converter.

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