CN103219736B - 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 frequency multiplication fluctuations

Technical field

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

Background technology

DC bus plays vital effect for permanent magnet direct-drive wind generator system, and providing of the conveying of magneto alternator active power and the stable DC voltage of 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 abnormal condition is subject to the extensive concern of Chinese scholars.Especially in the time of electrical network generation unbalanced fault, all there is 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 occur 2 times of power frequency fluctuations, this wave component will further cause DC bus-bar voltage 2 times of power frequency fluctuations largely, bring great threat to 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 permanent magnet direct-driving aerogenerator group at 2 times of power frequency fluctuations of the asymmetric intentional lower DC bus-bar voltage of electrical network at present, discloses following document:

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

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

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

Document (2) has been analyzed the mechanism of direct-drive permanent magnet synchronous aerogenerator group DC bus-bar voltage fluctuation under unbalanced source voltage, has proposed to be a kind ofly delivered to grid power 2 frequencys multiplication and to fluctuate and further suppress the object of DC voltage 2 frequencys multiplication fluctuations by eliminating grid side converter.But in the time of electrical network generation degree of depth unbalanced fault, line voltage occurs uneven largely, the method will take the most of current capacity of net side and suppress 2 frequencys multiplication fluctuations of direct voltage, and this cannot meet new grid-connected directive/guide wind-powered electricity generation unit is proposed to provide to electrical network the new demand of reactive power support.

Summary of the invention

For above-mentioned technical problem, the invention provides the control method that a kind of flywheel energy storage unit suppresses the 2 frequency multiplication fluctuations of permanent magnet direct-drive wind generator system DC side, the method adopts flywheel energy storage unit to absorb or delivered power, the fluctuating power compensation of realization to 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 frequency multiplication fluctuations, it is characterized in that, permanent magnet direct-driving aerogenerator system intermediate dc link both sides power under unbalanced grid faults 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 absorption or delivered power and realize the fluctuating power compensation to DC capacitor, realize the inhibition to DC voltage 2 frequency multiplication fluctuations.

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 controlling fly-wheel motor side converter, the concrete steps that realization control flywheel energy storage unit absorption or delivered power are realized the fluctuating power compensation to DC capacitor are 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 to positive-negative sequence and separate, be converted to the voltage signal of forward synchronous rotary axle system: the voltage signal of reverse sync rotary axis: the current signal of forward synchronous rotary axle system: the voltage signal of reverse sync rotary axis:

(2) calculate grid side power averaging component P by 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:

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

(3), according to step (1), calculate reactor instantaneous active power average value P _{gL_av}with reactive power mean value Q _{gL_av}and the sinusoidal component P of this reactor instantaneous active power mean value _{gL_sin2}with cosine component P _{gL_cos2}, computing formula is as follows:

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

(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) machine-side converter power output P _spoor with the grid side converter ac output end mouth performance number of step (4), using this difference as flywheel energy storage unit compensating direct current side 2 frequency multiplication fluctuating power set-points;

$\mathrm{\Δ}{P}_f^{*}=P_s-P_{\mathrm{gc}}$

(6) by DC side virtual voltage U _dcthe normal voltage default with this DC side make comparisons, deviation by after 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 formula, K _pand K _irepresent respectively proportionality coefficient and the integral coefficient of permagnetic synchronous motor outer voltage pi regulator;

(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:

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

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

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

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

(9) utilize current Hall transducer to gather 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 _fq; And form current inner loop control with the given instruction of step (8) permagnetic synchronous motor dq shaft current, its governing equation is:

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

In formula, K _fpand K _fibe respectively proportionality coefficient and the integral coefficient of the pi regulator of fly-wheel motor side converter control voltage, L _ffor the stator inductance of permagnetic synchronous motor, ω _ffor the rotor electric angle speed of permagnetic synchronous motor, ψ _ffor the permanent magnet flux linkage of permagnetic synchronous motor;

(10) by permanent-magnetic synchronous motor stator control voltage u _fd, u _fqafter the modulation of space vector pulse width modulation module, can obtain the switching signal of controlling 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 unbalanced grid faults, obtain flywheel energy storage power of motor control command, and then calculate the given instruction of fly-wheel motor q shaft current, controlling flywheel energy storage unit absorbs or delivered power, realize the fluctuating power compensation to DC capacitor, thereby realize the inhibition to DC voltage 2 frequency multiplication fluctuations.

Brief description of the drawings

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

Fig. 2 is the off line side electric current and voltage of unbalanced grid faults positive-negative sequence component computing block diagram;

Fig. 3 is the off line side power component of unbalanced grid faults computing block diagram;

Fig. 4 is the off line side reactor of unbalanced grid faults power component computing block diagram;

Fig. 5 is direct current pressure ring control block diagram in unbalanced grid faults process;

Fig. 6 does not adopt the inventive method and the effect contrast figure who adopts the inventive method under electrical network asymmetry 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 flywheel energy storage unit, this flywheel energy storage unit comprises flywheel side converter, permagnetic synchronous motor and the flywheel being connected with this permagnetic synchronous motor rotating shaft, flywheel energy storage unit absorbs or delivered power is realized the fluctuating power compensation to DC capacitor, suppress the 2 frequency multiplication fluctuations of permanent magnet direct-drive wind generator system DC voltage, for grid side converter provides reactive power support to lay the foundation to electrical network to greatest extent during electric network fault, effectively strengthen permanent magnet direct-drive wind power system low voltage crossing runnability.

Flywheel energy storage unit suppresses the control method of permanent magnet direct-drive wind generator system DC side 2 frequency multiplication fluctuations, permanent magnet direct-driving aerogenerator system intermediate dc link both sides power under unbalanced grid faults 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 absorption or delivered power and realize the fluctuating power compensation to DC capacitor, realize the inhibition to DC voltage 2 frequency multiplication fluctuations, concrete steps are as follows:

(1) as shown in Figure 2, grid side converter gathers electrical network three-phase voltage signal and three-phase current signal, this three-phase voltage signal and three-phase current signal are carried out to positive-negative sequence and separate, and the three-phase voltage signal that this separation is obtained and three-phase current signal are converted to respectively the voltage signal of forward synchronous rotary axle system through grid side converter positive-negative sequence separation modules: the voltage signal of reverse sync rotary axis: the current signal of forward synchronous rotary axle system: 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 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:

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

(3) by the reactor power component computing module of grid side converter according to step (1), calculate reactor instantaneous active power average value P _{gL_av}and the sinusoidal component P of this reactor instantaneous active power mean value _{gL_sin2}with cosine component P _{gL_cos2}, as shown in Figure 4, computing formula is as follows:

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

(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) machine-side converter power output P _spoor with the grid side converter ac output end mouth performance number of step (4), using this difference as flywheel energy storage unit compensating direct current side 2 frequency multiplication fluctuating power set-points;

$\mathrm{\Δ}{P}_f^{*}=P_s-P_{\mathrm{gc}}$

(6) as shown in Figure 5, by DC side virtual voltage U _dcthe normal voltage default with this DC side make comparisons, deviation by after 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 formula, K _pand K _irepresent respectively proportionality coefficient and the integral coefficient of permagnetic synchronous motor outer voltage pi regulator;

(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:

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

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

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

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

(9) utilize current Hall transducer to gather 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 _fq; And form current inner loop control with the given instruction of step (8) permagnetic synchronous motor dq shaft current, its governing equation is:

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

In formula, K _fpand K _fibe respectively proportionality coefficient and the integral coefficient of the pi regulator of fly-wheel motor side converter control voltage, L _ffor the stator inductance of permagnetic synchronous motor, ω _ffor the rotor electric angle speed of permagnetic synchronous motor, ψ _ffor the permanent magnet flux linkage of permagnetic synchronous motor;

(10) by permanent-magnetic synchronous motor stator control voltage u _fd, u _fqafter the modulation of space vector pulse width modulation module, can obtain the switching signal of controlling fly-wheel motor side converter.

Adopt the method, when electrical network occur single-phase while dropping into zero, as shown in Figure 6, there are 2 times of power frequency fluctuations largely in DC bus-bar voltage, fluctuation peak-to-peak value is up to 40V, and dc-link capacitance will bear periodically pulsing voltage stress largely and impact, and be unfavorable for its safe and stable operation.And when adopting after 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, effectively realize the object that suppresses 2 times of power frequency fluctuations of DC-link voltage.

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

Claims (1)

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 unbalanced grid faults 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 absorption or delivered power and realize the fluctuating power compensation to DC capacitor, realize the inhibition to DC voltage 2 frequency multiplication fluctuations;

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 controlling fly-wheel motor side converter, the concrete steps that realization control flywheel energy storage unit absorption or delivered power are realized the fluctuating power compensation to DC capacitor are 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 to positive-negative sequence and separate, be converted to the voltage signal of forward synchronous rotary axle system: the voltage signal of reverse sync rotary axis: the current signal of forward synchronous rotary axle system: the current signal of reverse sync rotary axis:

(2) calculate grid side power averaging component P by 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:

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

(3), according to step (1), calculate reactor instantaneous active power average value P _{gL_av}with reactive power mean value Q _{gL_av}and the sinusoidal component P of this reactor instantaneous active power mean value _{gL_sin2}with cosine component P _{gL_cos2}, computing formula is as follows:

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

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

$\begin{array}{c}{P}_{\mathrm{gc}}=P_g+P_{\mathrm{gL}}\\ =(P_{g\_\mathrm{av}}+P_{\mathrm{gL}\_\mathrm{av}})+(P_{g\_\cos 2}+P_{\mathrm{gL}\_\cos 2})\cos 2\mathrm{\ωt}\\ +(P_{g\_\sin 2}+P_{\mathrm{gL}\_\sin 2})\sin 2\mathrm{\ωt}\end{array}$

(5) machine-side converter power output P _spoor with the grid side converter ac output end mouth performance number of step (4), using this difference as flywheel energy storage unit compensating direct current side 2 frequency multiplication fluctuating power set-points;

$\mathrm{\Δ}{P}_f^{*}=P_s-P_{\mathrm{gc}}$

(6) by DC side virtual voltage U _dcthe normal voltage default with this DC side make comparisons, deviation by after 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 formula, K _pand K _irepresent respectively proportionality coefficient and the integral coefficient of permagnetic synchronous motor outer voltage pi regulator;

(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:

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

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

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

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

(9) utilize current Hall transducer to gather 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 _fq; And form current inner loop control with the given instruction of step (8) permagnetic synchronous motor dq shaft current, its governing equation is:

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

In formula, K _fpand K _fibe respectively proportionality coefficient and the integral coefficient of the pi regulator of fly-wheel motor side converter control voltage, L _ffor the stator inductance of permagnetic synchronous motor, ω _ffor the rotor electric angle speed of permagnetic synchronous motor, ψ _ffor the permanent magnet flux linkage of permagnetic synchronous motor;

(10) by permanent-magnetic synchronous motor stator control voltage u _fd, u _fqafter the modulation of space vector pulse width modulation module, can obtain the switching signal of controlling fly-wheel motor side converter.