CN103997064A - Method for restraining total output active power fluctuation of double-fed wind power system under unbalanced and harmonic distortion network voltage - Google Patents

Abstract

The invention discloses a method for restraining total output active power fluctuation of a double-fed wind power system through a series-connection network side converter under an unbalanced and harmonic distortion network voltage and relates to the field of control over series connection network side converters, parallel connection network side converters and motor side converters. A voltage controller adopted for the series connection network side converter can be used for rapidly restraining stator negative-sequence harmonic voltage components, five-time harmonic voltage components and seven-time harmonic voltage components and safe and stable operation of an electric generator is guaranteed. A reference current order of a parallel connection network side converter comprises fundamental harmonic positive-sequence current components, fundamental harmonic negative-sequence current components, five-time harmonic current components and seven-time harmonic components under a forward-direction synchronous revolution coordinate system. A current controller adopted for the parallel connection network side converter can simultaneously, accurately and rapidly adjust direct components, second harmonic generation alternating components and sixth harmonic generation alternating components. Total output active power second harmonic generation fluctuation and sixth harmonic generation fluctuation of the system can be guaranteed and the electric energy quality and stability of a power grid connected to the double-fed sensing wind power system are effectively improved.

Description

The total active power of output fluctuation of double-fed wind power system inhibition method under imbalance and harmonic distortion line voltage

Technical field

The present invention relates to adopt the double-fed induction wind generator system technological improvement of series connection grid side converter, particularly relate to the total active power of output fluctuation of the double-fed induction wind power system inhibition method that adopts series connection grid side converter under imbalance and harmonic distortion line voltage, belong to power control technology field.

Background technology

Along with a large amount of appearance of imbalance in electric power system or nonlinear load, especially for some asymmetric fault, in line voltage, can there are uneven and two kinds of disadvantageous disturbances of harmonic distortion simultaneously, for the remote wind energy turbine set of access light current net, the possibility that these two kinds of disturbances coexist is larger.The imbalance of line voltage and harmonic distortion meeting cause DFIG stator voltage to occur uneven and distortion, and then cause stator and rotor current imbalance and distortion, the fluctuation of output of a generator, electromagnetic torque and system active power of output, will have a strong impact on the quality of power supply of safe and stable operation and system feed-in electrical network of generator.On the other hand, for large-scale grid-connected double-fed induction wind power system, if lack the impact of considering uneven and harmonic wave network deformation voltage in its Excitation Control Strategy, may make generator system because of overvoltage and overcurrent off-the-line from electrical network, this cannot meet the requirement of modern power systems to wind-electricity integration.At present existing scholar has launched research with regard to operation action and the control strategy of DFIG system under imbalance and harmonic distortion line voltage, as published following document:

(1)Xu?H,Hu?J,He?Y.Integrated?Modeling?and?Enhanced?control?of?DFIG?under?unbalanced?and?distorted?grid?voltage?conditions[J].IEEE?Transactions?on?Energy?Conversion,2012,27(3):725-736.

(2)Hu?J,Xu?H,He?Y.Coordinated?control?of?DFIG's?RSC?and?GSC?under?generalized?unbalanced?and?distorted?grid?voltage?conditions[J].IEEE?Transactions?on?Industrial?Electronics,2013,60(7):2808-2819.

Document (1) proposes adoption rate integration-double-frequency resonance controller under forward synchronization rotational coordinate ax system and realizes the floating tracking control to rotor fundamental current and harmonic current, and then proposition suppresses the fluctuation of stator active power of output, realize stator or rotor current balance and undistorted, eliminate four of electromagnetic torque fluctuations and control target.Described control strategy all cannot ensure that due to the restriction of rotor current control variables stator and rotor current balance type is undistorted simultaneously, and therefore the unbalanced heating of stator and rotor winding and harmonic loss or stator power and electromagnetic torque fluctuation still exist in DFIG.In addition,, due to the existence of grid side converter, the control strategy of carrying can not be realized the inhibition to the total active power of output fluctuation of system.

Document (2) proposes to utilize the proportional integral-double-frequency resonance controller under forward synchronous rotary axle system to coordinate to control rotor-side converter and grid side converter, to realize the inhibition to electromagnetic torque and the total active power of output fluctuation of system, under described control strategy there is imbalance and harmonic distortion in stator and rotor electric current simultaneously, therefore the extra heating of stator and rotor winding still exists, and this will affect the life-span of winding insulation material.

Summary of the invention

For prior art above shortcomings, the object of the present invention is to provide a kind of total active power of output fluctuation of the double-fed induction wind power system inhibition method that adopts series connection grid side converter under imbalance and harmonic distortion line voltage, this control method has also realized the inhibition to the total active power of output fluctuation of DFIG system in ensureing generator safe and stable operation.

Technical scheme of the present invention is achieved in that

The total active power of output fluctuation of the double-fed induction wind power system inhibition method that adopts series connection grid side converter under imbalance and harmonic distortion line voltage, this method relates to control, the control of parallel-connection network side converter and the control of motor side converter to series connection grid side converter;

The control step of described series connection grid side converter is:

A1) utilize voltage hall sensor to gather electrical network three-phase voltage signal u _gabcand double fed induction generators stator three-phase voltage signal u _sabc;

A2) by the electrical network three-phase voltage signal u gathering _gabcafter digital phase-locked loop PLL, obtain electrical network positive sequence voltage electrical degree θ _g+and synchronous electric angular velocity omega;

A3) by the electrical network three-phase voltage signal u gathering _gabc, generator unit stator three-phase voltage signal u _sabcarrive the permanent power conversion of the static two-phase α β system of axis, voltage signal, i.e. u under the convert to static two-phase α β system of axis through the static three-phase abc system of axis respectively _{g α β}, u _{s α β};

A4) adopt electrical network positive sequence voltage oriented approach, by steps A 3 gained u _{g α β}through phase sequence separation module, extract respectively the lower line voltage fundamental positive sequence of forward synchronous angular velocity rotatable coordinate axis system the lower line voltage negative sequence component of reverse sync angular speed rotatable coordinate axis system line voltage 5 order harmonic components u under 5 times of synchronous angular velocity reverse rotation systems of axis be rotated in the forward line voltage 7 order harmonic components under the system of axis with 7 times of synchronous angular velocities

A5) adopt electrical network positive sequence voltage oriented approach, by steps A 3 gained u _{s α β}after the permanent power conversion of forward synchronous angular velocity rotatable coordinate axis system, obtain stator voltage dq axle component under forward synchronous angular velocity rotatable coordinate axis system through the static two-phase α β system of axis

A6) under forward synchronous angular velocity rotatable coordinate axis system, steps A 4 is obtained obtain with steps A 5 both differences are sent into voltage controller and are regulated;

A7) the control voltage u using the output of steps A 6 voltage controllers as series connection grid side converter inhibition stator negative phase-sequence and harmonic voltage _seriesdq;

A8) series connection grid side converter control voltage u steps A 7 being obtained _seriesdqbe tied to the permanent power conversion of the static two-phase α β system of axis through forward synchronous angular velocity rotatable coordinate axis, can obtain controlling voltage u under the static two-phase α β system of axis _{series α β};

A9) by the series connection grid side converter control voltage u of steps A 8 gained _{series α β}with DC voltage U _dcproduce series connection grid side converter PWM by space vector modulation and drive signal;

The control step of described parallel-connection network side converter is:

B1) utilize voltage hall sensor to gather electrical network three-phase voltage signal u _gabc, current Hall transducer gathers double fed induction generators stator three-phase current signal i _sabcand the three-phase current signal i of parallel-connection network side converter _gabc;

B2) utilize voltage hall sensor to gather DC voltage signal U _dc;

The three-phase current signal of the electrical network three-phase voltage signal B3) B1 being gathered and double fed induction generators stator, parallel-connection network side converter is respectively after the static three-phase abc system of axis arrives the permanent power conversion of the static two-phase α β system of axis, voltage, current signal under the convert to static two-phase α β system of axis, i.e. u _{g α β}, i _{s α β}, i _{g α β};

B4) u step B3 being obtained _{g α β}, i _{s α β}, i _{g α β}after the permanent power conversion that through the static two-phase α β system of axis to forward synchronous angular velocity rotatable coordinate axis is respectively, obtain line voltage and stator, parallel-connection network side converter current dq axle component under forward synchronous angular velocity rotatable coordinate axis system

B5) DC bus-bar voltage of parallel-connection network side converter regulates and adopts pi regulator control, its adjuster output and DC bus-bar voltage set-point form DC bus-bar voltage average active power set-point computing formula is

$P_{g\_\mathrm{av}}^{*}=(K_{\mathrm{pu}}+K_{\mathrm{iu}}/s)(U_{\mathrm{dc}}^{*}-U_{\mathrm{dc}})\·U_{\mathrm{dc}}^{*}$

Wherein: represent that parallel-connection network side converter maintains DC bus-bar voltage and stablizes required average active power instruction, for DC bus-bar voltage set-point, K _puand K _iube respectively DC bus-bar voltage adjuster proportionality coefficient and integral coefficient;

B6) parallel-connection network side converter using positive sequence line voltage is oriented to d axle, by steps A 4, B4, B5 gained send into parallel-connection network side converter reference current command calculations module, obtain under forward synchronous angular velocity rotatable coordinate axis system and comprise fundamental positive sequence, negative phase-sequence and harmonic components in interior parallel-connection network side converter reference current instruction

B7) by step B6 gained with B4 gained difference send into current controller and regulate, current controller is output as

B8) obtain according to step B4, B6 and the output of step B7 current controller calculate parallel-connection network side convertor controls voltage

B9) by B8 gained parallel-connection network side convertor controls voltage be tied to the permanent power conversion of the static two-phase α β system of axis through forward synchronous angular velocity rotatable coordinate axis, can obtain controlling voltage u under the static two-phase α β system of axis _{c α β};

B10) by the parallel-connection network side convertor controls voltage u of step B9 gained _{c α β}with DC voltage U _dcproduce parallel-connection network side converter PWM by space vector modulation and drive signal;

The control strategy of motor side converter

(C1) motor side converter using conventional vector control strategy, it controls voltage and DC voltage U _dcproduce motor side converter PWM by space vector modulation and drive signal.

Described steps A 4) comprise following sub-step:

A4.1) by u _{g α β}permanent power conversion through the static two-phase α β system of axis to forward synchronous angular velocity rotatable coordinate axis system, then after 2 ω, 6 ω trapper filtering, obtain line voltage positive sequence component dq axle component under forward synchronous angular velocity rotatable coordinate axis system

A4.2) by u _{g α β}permanent power conversion through the static two-phase α β system of axis to reverse sync angular speed rotatable coordinate axis system, then after 2 ω, 4 ω, 8 ω trapper filtering, obtain line voltage negative sequence component dq axle component under reverse sync angular speed rotatable coordinate axis system

A4.3) by u _{g α β}through the permanent power conversion of the static two-phase α β system of axis to the 5 times synchronous angular velocity reverse rotation system of axis, then after 4 ω, 6 ω, 12 ω trapper filtering, obtain line voltage 5 order harmonic components dq axle component under 5 times of synchronous angular velocity reverse rotation systems of axis

A4.4) by u _{g α β}be rotated in the forward the permanent power conversion of the system of axis through the static two-phase α β system of axis to 7 times synchronous angular velocity, then after 6 ω, 8 ω, 12 ω trapper filtering, obtain line voltage 7 order harmonic components and be rotated in the forward dq axle component under the system of axis 7 times of synchronous angular velocities

Steps A 6) described voltage controller adds that by a traditional PI adjuster resonant regulator that two resonance frequencys are respectively 2 times, 6 times mains frequencies combines, its transfer function is:

$C_{\mathrm{uPI}-\mathrm{DFR}}\left(s\right)=K_{\mathrm{up}}+\frac{K_{\mathrm{ui}}}{s}+\frac{s{K}_{\mathrm{ur}1}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ur}2}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}2}s+{(\±6\mathrm{\ω})}^2}$

C in formula _uPI-DFR(s) be the transfer function of voltage controller; K _up+, K _uibe respectively proportionality coefficient, the integral coefficient of voltage controller; K _ur1, K _ur2be respectively the resonance coefficient of two resonant regulators; ω _cu1, ω _cu2be respectively the cut-off frequency of two resonant regulators; ω is synchronous electric angular speed; S refers to complex variable.

Described step B6) comprise the following steps:

B6.1) calculate parallel-connection network side converter fundamental positive sequence, negative-sequence current reference instruction:

$i_{\mathrm{gd}+}^{+*}=\frac{u_{\mathrm{gd}+}^{+}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gq}-}^{-}\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+2}-u_{g-}^{-2}}$

$i_{\mathrm{gq}+}^{+*}=\frac{u_{\mathrm{gd}+}^{+}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}+\frac{u_{\mathrm{gq}-}^{-}\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+2}+u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+2}-u_{g-}^{-2}}$

$i_{\mathrm{gd}-}^{-*}=\frac{k_1\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+4}-u_{g-}^{-4}}+\frac{k_2\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+4}-u_{g-}^{-4}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}+\frac{u_{\mathrm{gq}-}^{-}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}$

$i_{\mathrm{gq}-}^{-*}=\frac{k_2\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+4}-u_{g-}^{-4}}+\frac{k_3\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+4}-u_{g-}^{-4}}-\frac{u_{\mathrm{gq}-}^{-}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}+\frac{u_{\mathrm{gd}-}^{-}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}$

Wherein $\left\{\begin{array}{c}{k}_1=u_{\mathrm{gd}+}^{+3}-u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gq}-}^{-2}+u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-2}\\ k_2=2u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-}\·u_{\mathrm{gq}-}^{-}\\ k_3=u_{\mathrm{gd}+}^{+3}-u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-2}+u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gq}-}^{-2}\\ P_{\mathrm{series}\_\cos 2}=-u_{\mathrm{gd}-}^{-}{i}_{\mathrm{sd}+}^{+}-u_{\mathrm{gq}-}^{-}{i}_{\mathrm{sq}+}^{+}\\ P_{\mathrm{series}\_\sin 2}=-u_{\mathrm{gq}-}^{-}{i}_{\mathrm{sd}+}^{+}+u_{\mathrm{gd}-}^{-}{i}_{\mathrm{sq}+}^{+}\end{array}\right.$

set according to the reactive requirement of electrical network;

B6.2) calculating parallel-connection network side converter 5 times, 7 subharmonic current reference instructions are:

$\begin{array}{c}{i}_{\mathrm{gd}5-}^{\text{5-*}}=((P_{\mathrm{series}\_\cos 6}-(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gq}+}^{+*})\\ +(-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}7+}^{7+}-u_{\mathrm{gq}5-}^{5-})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gq}5-}^{\text{5-*}}=((P_{\mathrm{series}\_\sin 6}-(u_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gq}+}^{+*})\\ -(-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}+(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gd}7+}^{\text{7+*}}=((P_{\mathrm{series}\_\cos 6}-(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gq}+}^{+*})\\ -(-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}7+}^{7+}-u_{\mathrm{gq}5-}^{5-})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gq}7+}^{\text{7+*}}=-((P_{\mathrm{series}\_\sin 6}-(u_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gq}+}^{+*})\\ +(-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}+(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

Wherein $\left\{\begin{array}{c}{P}_{\mathrm{series}\_\cos 6}=({-u}_{\mathrm{gd}5-}^{5-}-u_{\mathrm{gd}7+}^{7+})i_{\mathrm{sd}+}^{+}+({-u}_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{sq}+}^{+}\\ P_{\mathrm{series}\_\sin 6}=(-u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{sd}+}^{+}+(u_{\mathrm{gd}5-}^{5-}-u_{\mathrm{gd}7+}^{7+})i_{\mathrm{sq}+}^{+}\end{array}\right.;$

B6.3) by the parallel-connection network side converter negative phase-sequence calculating, 5 times, 7 subharmonic current instructions, that is: being rotated in the forward the system of axis through reverse sync angular speed rotatable coordinate axis system, 5 times of synchronous angular velocity reverse rotation systems of axis, 7 times of synchronous angular velocities is respectively permanent power conversion to forward synchronous angular velocity rotatable coordinate axis, can obtain respectively the lower parallel-connection network side converter negative phase-sequence of forward synchronous angular velocity rotatable coordinate axis system, 5 times, 7 subharmonic current set-points again will with parallel-connection network side converter fundamental positive sequence current-order be added, can obtain the current-order of the lower parallel-connection network side converter of forward synchronous angular velocity rotatable coordinate axis system that is:

$i_{\mathrm{gdq}}^{+*}=i_{\mathrm{gdq}+}^{+*}+i_{\mathrm{gdq}-}^{+*}+i_{\mathrm{gdq}5-}^{+*}+i_{\mathrm{gdq}7+}^{+*}=i_{\mathrm{gdq}+}^{+*}+i_{\mathrm{gdq}-}^{-*}{e}^{-j2{\mathrm{\θ}}_g}+i_{\mathrm{gdq}5-}^{5-*}{e}^{-j6{\mathrm{\θ}}_g}+i_{\mathrm{gdq}7+}^{7+*}{e}^{j6{\mathrm{\θ}}_g}.$

Step B7) described current controller adds that by a traditional PI adjuster resonant regulator that two resonance frequencys are respectively 2 times, 6 times mains frequencies combines, its transfer function is:

$C_{\mathrm{iPI}-\mathrm{DFR}}\left(s\right)=K_{\mathrm{ip}}+\frac{K_{\mathrm{ii}}}{s}+\frac{s{K}_{\mathrm{ir}1}}{s^2+{\mathrm{\ω}}_{\mathrm{ci}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ir}2}}{s^2+{\mathrm{\ω}}_{\mathrm{ci}2}s+{(\±6\mathrm{\ω})}^2}$

C in formula _iPI-DFR(s) be the transfer function of current controller; K _ip, K _iibe respectively proportionality coefficient, the integral coefficient of current controller; K _ir1, K _ir2be respectively the resonance coefficient of two resonant regulators; ω _ci1, ω _ci2be respectively the cut-off frequency of two resonant regulators; ω is synchronous electric angular speed; S refers to complex variable.

The beneficial effect of this method is:

This method realized under imbalance and harmonic distortion line voltage adopt the dual feedback wind power generation system stator and rotor three-phase balance of series connection grid side converter undistorted, output power of motor and electromagnetic torque ripple disable, ensure the safe and stable operation of generator, also make the total active power of output degree of fluctuation of system greatly reduce, effectively improved DFIG system institute the electrical network quality of power supply under imbalance and harmonic distortion line voltage simultaneously.

Brief description of the drawings

Fig. 1 is that the present invention adopts series connection grid side converter double-fed induction wind power system control block diagram.

Fig. 2 is line voltage phase sequence separation module.

Fig. 3 is the lower parallel-connection network side converter reference current command calculations module of forward synchronization rotational coordinate ax system.

Fig. 4 is that unbalanced source voltage degree is that 4%, 5 time, 7 subharmonic voltage content are under 3% electrical network condition, the system emulation waveform that adopts traditional control strategy to obtain.

Fig. 5 is that unbalanced source voltage degree is that 4%, 5 time, 7 subharmonic voltage content are under 3% electrical network condition, the system emulation waveform that adopts control method of the present invention to obtain.

Embodiment

Below in conjunction with accompanying drawing, specific embodiment of the invention scheme is described in detail.

As shown in Figure 1, under imbalance of the present invention and harmonic distortion line voltage, adopt the total active power of output fluctuation of the double-fed induction wind power system inhibition method of series connection grid side converter, the control object that it comprises has: direct-current chain electric capacity 1, voltage hall sensor 2, current Hall transducer 3, series connection grid side converter 4, space vector modulation module 5, parallel-connection network side converter reference current command calculations module 6, the static three-phase abc system of axis is to the permanent power conversion module 7 of the static two-phase α β system of axis, the static two-phase α β system of axis is to the permanent power conversion module 8 of forward synchronous angular velocity rotatable coordinate axis system, the static two-phase α β system of axis is to the permanent power conversion module 9 of reverse sync angular speed rotatable coordinate axis system, the permanent power conversion module 10 of the static two-phase α β system of axis to the 5 times synchronous angular velocity reverse rotation system of axis, the static two-phase α β system of axis to 7 times synchronous angular velocity is rotated in the forward the permanent power conversion module 11 of the system of axis, reverse sync angular speed rotatable coordinate axis is tied to the permanent power conversion module 12 of forward synchronous angular velocity rotatable coordinate axis system, 5 times of permanent power conversion modules 13 that the synchronous angular velocity reverse rotation system of axis to forward synchronous angular velocity rotatable coordinate axis is, 7 times of synchronous angular velocities are rotated in the forward the permanent power conversion module 14 of the system of axis to forward synchronous angular velocity rotatable coordinate axis system, forward synchronous angular velocity rotatable coordinate axis is tied to the permanent power conversion module 15 of the static two-phase α β system of axis, phase-locked loop (PLL) 16.

The present invention relates to control, the control of parallel-connection network side converter and the control of motor side converter to series connection grid side converter; Its concrete implementation step is as follows:

(A) described series connection grid side converter control step:

A1) utilize voltage hall sensor 2 to gather electrical network three-phase voltage signal u _gabcand double fed induction generators stator three-phase voltage signal u _sabc;

A2) by the electrical network three-phase voltage signal u gathering _gabcafter digital phase-locked loop (PLL) 16, obtain electrical network positive sequence voltage electrical degree θ _g+and synchronous electric angular velocity omega;

A3) three-phase voltage signal of the electrical network gathering, generator unit stator is arrived to the permanent power conversion module 7 of the static two-phase α β system of axis, voltage signal, i.e. u under the convert to static two-phase α β system of axis through the static three-phase abc system of axis respectively _{g α β}, u _{s α β};

A4) adopt electrical network positive sequence voltage oriented approach, by steps A 3 gained u _{g α β}through phase sequence separation module, extract respectively the lower line voltage fundamental positive sequence of forward synchronous angular velocity rotatable coordinate axis system the lower line voltage negative sequence component of reverse sync angular speed rotatable coordinate axis system line voltage 5 order harmonic components u under 5 times of synchronous angular velocity reverse rotation systems of axis be rotated in the forward line voltage 7 order harmonic components under the system of axis with 7 times of synchronous angular velocities

With reference to Fig. 2, the concrete implementation step of phase sequence separation module proposed by the invention is as follows:

A4.1) by u _{g α β}permanent power conversion module 8 through the static two-phase α β system of axis to forward synchronous angular velocity rotatable coordinate axis system, then after 2 ω, 6 ω trapper filtering, obtain line voltage positive sequence component dq axle component under forward synchronous angular velocity rotatable coordinate axis system

A4.2) by u _{g α β}permanent power conversion module 9 through the static two-phase α β system of axis to reverse sync angular speed rotatable coordinate axis system, then after 2 ω, 4 ω, 8 ω trapper filtering, obtain line voltage negative sequence component dq axle component under reverse sync angular speed rotatable coordinate axis system

A4.3) by u _{g α β}through the permanent power conversion module 10 of the static two-phase α β system of axis to the 5 times synchronous angular velocity reverse rotation system of axis, then after 4 ω, 6 ω, 12 ω trapper filtering, obtain line voltage 5 order harmonic components dq axle component under 5 times of synchronous angular velocity reverse rotation systems of axis

A4.4) by u _{g α β}be rotated in the forward the permanent power conversion module 11 of the system of axis through the static two-phase α β system of axis to 7 times synchronous angular velocity, then after 6 ω, 8 ω, 12 ω trapper filtering, obtain line voltage 7 order harmonic components and be rotated in the forward dq axle component under the system of axis 7 times of synchronous angular velocities

A5) adopt electrical network positive sequence voltage oriented approach, by steps A 3 gained u _{s α β}permanent power conversion module 8 through the static two-phase α β system of axis to forward synchronous angular velocity rotatable coordinate axis system, obtains stator voltage dq axle component under forward synchronous angular velocity rotating coordinate system

A6) under forward synchronous angular velocity rotatable coordinate axis system, steps A 4 is obtained obtain with steps A 5 both differences are sent into voltage controller and are regulated;

Wherein, voltage controller adds that by a traditional PI adjuster resonant regulator that two resonance frequencys are respectively 2 times, 6 times mains frequencies combines, and its transfer function is:

$C_{\mathrm{uPI}-\mathrm{DFR}}\left(s\right)=K_{\mathrm{up}}+\frac{K_{\mathrm{ui}}}{s}+\frac{s{K}_{\mathrm{ur}1}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ur}2}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}2}s+{(\±6\mathrm{\ω})}^2}$

K in formula _up, K _uibe respectively proportionality coefficient, the integral coefficient of voltage controller; K _ur1, K _ur2be respectively the resonance coefficient of two resonant regulators; ω _cu1, ω _cu2be respectively the cut-off frequency of two resonant regulators, the responsive bandwidth that is mainly used in increasing resonant regulator to be to reduce its sensitivity to resonance point frequency fluctuation, desirable 5～15rad/s in real system; ω is synchronous electric angular speed;

A7) the control voltage u using the output of steps A 6 voltage controllers as series connection grid side converter inhibition stator negative phase-sequence and harmonic voltage _seriesdq, that is:

$u_{\mathrm{seriesdq}}=[K_{\mathrm{up}}+\frac{K_{\mathrm{ui}}}{s}+\frac{s{K}_{\mathrm{ur}1}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ur}2}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}2}s+{(\±6\mathrm{\ω})}^2}](u_{\mathrm{gdq}+}^{+}-u_{\mathrm{sdq}}^{+})$

A8) series connection grid side converter control voltage u steps A 7 being obtained _seriesdqbe tied to the permanent power conversion module 15 of the static two-phase α β system of axis through forward synchronous angular velocity rotatable coordinate axis, can obtain controlling voltage u under the static two-phase α β system of axis _{series α β};

A9) by the series connection grid side converter control voltage u of steps A 8 gained _{series α β}with DC voltage U _dcproduce series connection grid side converter PWM by space vector modulation module 5 and drive signal.

(B) the control step of described parallel-connection network side converter is:

B1) utilize voltage hall sensor 2 to gather electrical network three-phase voltage signal u _gabc, current Hall transducer 3 gathers double fed induction generators stator three-phase current signal i _sabcand the three-phase current signal i of parallel-connection network side converter _gabc;

B2) utilize voltage hall sensor 2 to gather DC voltage signal U _dc;

B3) by the three-phase current signal of the electrical network three-phase voltage signal collecting and double fed induction generators stator, parallel-connection network side converter respectively through the static three-phase abc system of axis to the permanent power conversion module 7 of the static two-phase α β system of axis, voltage, current signal under the convert to static two-phase α β system of axis, i.e. u _{g α β}, i _{s α β}, i _{g α β};

B4) u step B3 being obtained _{g α β}, i _{s α β}, i _{g α β}the permanent power conversion module 8 to forward synchronous angular velocity rotating coordinate system through the static two-phase α β system of axis respectively, obtains line voltage and stator, parallel-connection network side converter current dq axle component under forward synchronization rotational coordinate ax system

B5) DC bus-bar voltage of parallel-connection network side converter regulates and adopts pi regulator control, its adjuster output and DC bus-bar voltage set-point form DC bus-bar voltage average active power set-point referring to Fig. 1, that is:

$P_{g\_\mathrm{av}}^{*}=(K_{\mathrm{pu}}+K_{\mathrm{iu}}/s)(U_{\mathrm{dc}}^{*}-U_{\mathrm{dc}})\·U_{\mathrm{dc}}^{*}$

Wherein: represent that parallel-connection network side converter maintains DC bus-bar voltage and stablizes required average active power instruction, for DC bus-bar voltage set-point, K _puand K _iube respectively DC bus-bar voltage adjuster proportionality coefficient and integral coefficient;

B6) parallel-connection network side converter using positive sequence line voltage is oriented to d axle, by steps A 4, B4, B5 gained send into parallel-connection network side converter reference current command calculations module, obtain under forward synchronous angular velocity rotatable coordinate axis system and comprise fundamental positive sequence, negative phase-sequence and harmonic components in interior parallel-connection network side converter reference current instruction

Parallel-connection network side converter reference current command calculations module 6 of the present invention is shown in Fig. 3, and concrete implementation step is as follows:

B6.1) calculate parallel-connection network side converter fundamental positive sequence, negative-sequence current reference instruction:

$i_{\mathrm{gd}+}^{+*}=\frac{u_{\mathrm{gd}+}^{+}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gq}-}^{-}\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+2}-u_{g-}^{-2}}$

$i_{\mathrm{gq}+}^{+*}=-\frac{u_{\mathrm{gd}+}^{+}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}+\frac{u_{\mathrm{gq}-}^{-}\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+2}+u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+2}+u_{g-}^{-2}}$

$i_{\mathrm{gd}-}^{-*}=\frac{k_1\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+4}-u_{g-}^{-4}}+\frac{k_2\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+4}-u_{g-}^{-4}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}+\frac{u_{\mathrm{gq}-}^{-}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}$

$i_{\mathrm{gq}-}^{-*}=\frac{k_2\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+4}-u_{g-}^{-4}}+\frac{k_3\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+4}-u_{g-}^{-4}}-\frac{u_{\mathrm{gq}-}^{-}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}$

Wherein $\left\{\begin{array}{c}{k}_1=u_{\mathrm{gd}+}^{+3}-u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gq}-}^{-2}+u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-2}\\ k_2=2u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-}\·u_{\mathrm{gq}-}^{-}\\ k_3=u_{\mathrm{gd}+}^{+3}-u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-2}+u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gq}-}^{-2}\\ P_{\mathrm{series}\_\cos 2}=-u_{\mathrm{gd}-}^{-}{i}_{\mathrm{sd}+}^{+}-u_{\mathrm{gq}-}^{-}{i}_{\mathrm{sq}+}^{+}\\ P_{\mathrm{series}\_\sin 2}=-u_{\mathrm{gq}-}^{-}{i}_{\mathrm{sd}+}^{+}+u_{\mathrm{gd}-}^{-}{i}_{\mathrm{sq}+}^{+}\end{array}\right.$

can set according to the reactive requirement of electrical network.

B6.2) calculating parallel-connection network side converter 5 times, 7 subharmonic current reference instructions are:

$\begin{array}{c}{i}_{\mathrm{gd}5-}^{\text{5-*}}=((P_{\mathrm{series}\_\cos 6}-(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gq}+}^{+*})\\ +(-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}7+}^{7+}-u_{\mathrm{gq}5-}^{5-})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gq}5-}^{\text{5-*}}=((P_{\mathrm{series}\_\sin 6}-(u_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gq}+}^{+*})\\ -(-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}+(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gd}7+}^{\text{7+*}}=((P_{\mathrm{series}\_\cos 6}-(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gq}+}^{+*})\\ -(-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}7+}^{7+}-u_{\mathrm{gq}5-}^{5-})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gq}7+}^{\text{7+*}}=-((P_{\mathrm{series}\_\sin 6}-(u_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gq}+}^{+*})\\ +(-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}+(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

Wherein $\left\{\begin{array}{c}{P}_{\mathrm{series}\_\cos 6}=({-u}_{\mathrm{gd}5-}^{5-}-u_{\mathrm{gd}7+}^{7+})i_{\mathrm{sd}+}^{+}+({-u}_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{sq}+}^{+}\\ P_{\mathrm{series}\_\sin 6}=(-u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{sd}+}^{+}+(u_{\mathrm{gd}5-}^{5-}-u_{\mathrm{gd}7+}^{7+})i_{\mathrm{sq}+}^{+}\end{array}\right..$

B6.3) by the parallel-connection network side converter negative phase-sequence calculating, 5 times, 7 subharmonic current instructions, that is: being rotated in the forward the system of axis through reverse sync angular speed rotatable coordinate axis system, 5 times of synchronous angular velocity reverse rotation systems of axis, 7 times of synchronous angular velocities is respectively permanent power conversion module 12,13,14 to forward synchronous angular velocity rotatable coordinate axis, can obtain respectively the lower parallel-connection network side converter negative phase-sequence of forward synchronous angular velocity rotatable coordinate axis system, 5 times, 7 subharmonic current set-points again will with parallel-connection network side converter fundamental positive sequence current-order be added, can obtain the current-order of the lower parallel-connection network side converter of forward synchronous angular velocity rotatable coordinate axis system that is:

$i_{\mathrm{gdq}}^{+*}=i_{\mathrm{gdq}+}^{+*}+i_{\mathrm{gdq}-}^{+*}+i_{\mathrm{gdq}5-}^{+*}+i_{\mathrm{gdq}7+}^{+*}=i_{\mathrm{gdq}+}^{+*}+i_{\mathrm{gdq}-}^{-*}{e}^{-j2{\mathrm{\θ}}_g}+i_{\mathrm{gdq}5-}^{5-*}{e}^{-j6{\mathrm{\θ}}_g}+i_{\mathrm{gdq}7+}^{7+*}{e}^{j6{\mathrm{\θ}}_g};$

B7) by step B6 gained with B4 gained difference send into current controller and regulate, current controller is output as that is:

$u_{\mathrm{cdq}}^{{+}^{\′}}=C_{\mathrm{iPI}-\mathrm{DFR}}\left(s\right)(i_{\mathrm{gdq}}^{+*}-i_{\mathrm{gdq}}^{+})$

Wherein, current controller adds that by a traditional PI adjuster resonant regulator that two resonance frequencys are respectively 2 times, 6 times mains frequencies combines, and its transfer function is:

$C_{\mathrm{iPI}-\mathrm{DFR}}\left(s\right)=K_{\mathrm{ip}}+\frac{K_{\mathrm{ii}}}{s}+\frac{s{K}_{\mathrm{ir}1}}{s^2+{\mathrm{\ω}}_{\mathrm{ci}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ir}2}}{s^2+{\mathrm{\ω}}_{\mathrm{ci}2}s+{(\±6\mathrm{\ω})}^2}$

Ki in formula _p, K _iibe respectively proportionality coefficient, the integral coefficient of current controller; K _ir1, K _ir2be respectively the resonance coefficient of two resonant regulators; ω _ci1, ω _ci2be respectively the cut-off frequency of two resonant regulators, the responsive bandwidth that is mainly used in increasing resonant regulator to be to reduce its sensitivity to resonance point frequency fluctuation, desirable 5～15rad/s in real system; ω is synchronous electric angular speed;

B8) obtain according to step B4, B6 and the output of step B7 current controller calculate parallel-connection network side convertor controls voltage that is:

$\begin{array}{c}{u}_{\mathrm{cdq}}^{+}=u_{\mathrm{cdq}}^{{+}^{\′}}+u_{\mathrm{gdq}}^{+}-R_g{i}_{\mathrm{gdq}}^{+}-\mathrm{j\ω}{L}_g{i}_{\mathrm{gdq}}^{+}\\ =C_{\mathrm{iPI}-\mathrm{DFR}}\left(s\right)(i_{\mathrm{gdq}}^{+*}-i_{\mathrm{gdq}}^{+})+u_{\mathrm{gdq}}^{+}-R_g{i}_{\mathrm{gdq}}^{+}-\mathrm{j\ω}{L}_g{i}_{\mathrm{gdq}}^{+}\end{array}----\left(1\right)$

Wherein ω is synchronous electric angular speed, R _g, L _gbe respectively parallel-connection network side converter reactor resistance, inductance.

B9) by B8 gained parallel-connection network side convertor controls voltage be tied to the permanent power conversion module 13 of the static two-phase α β system of axis through forward synchronous angular velocity rotatable coordinate axis, can obtain controlling voltage u under the static two-phase α β system of axis _{c α β};

B10) by the parallel-connection network side convertor controls voltage u of step B9 gained _{c α β}with DC voltage U _dcproduce series connection grid side converter PWM by space vector modulation module 5 and drive signal.

(C) the control step of described motor side converter is:

(C1) motor side converter using conventional vector control strategy, it controls voltage and DC voltage U _dcproduce motor side converter PWM by space vector modulation module 5 and drive signal.

Effect explanation of the present invention:

Fig. 4 has provided the system emulation result that adopts traditional control strategy under forward synchronous angular velocity rotating coordinate system.Owing to connecting, grid side converter and parallel-connection network side converter adopt single pi regulator to realize the control to stator voltage and current on line side respectively under forward synchronization rotational coordinate ax system, be subject to the restriction of pi regulator bandwidth, by making still to exist in stator voltage and current on line side the negative phase-sequence of larger content, 5 times, 7 order harmonic components, can not eliminate the harmful effect that stator voltage negative phase-sequence and harmonic component are brought whole system.In addition, in the total active power of output of whole system, also all there is pulsation by a relatively large margin, reduced entire system runnability.Fig. 5 has provided employing control method system emulation of the present invention result.Can find out from Fig. 5 (o), under imbalance and harmonic distortion line voltage, by effective control of series connection grid side converter has been eliminated to negative phase-sequence and the harmonic component in the stator voltage of DFIG, generator is in symmetrical steady operational status, stator and rotor three-phase balance is undistorted, the equal ripple disable of output of a generator and electromagnetic torque, as Fig. 5 (c), (d), (f) with (g).In addition, by the effective control to current on line side (Fig. 5 (k)～(n)), 2 times, 6 frequency multiplication fluctuations in whole system active power of output are eliminated, effectively improved DFIG system under imbalance and harmonic distortion line voltage overall operation performance and and the stability of electrical network, as shown in Fig. 5 (h).

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 (5)

1. under imbalance and harmonic distortion line voltage, adopt the total active power of output fluctuation of the double-fed induction wind power system inhibition method of series connection grid side converter, it is characterized in that, this method relates to control, the control of parallel-connection network side converter and the control of motor side converter to series connection grid side converter;

The control step of described series connection grid side converter is:

A1) utilize voltage hall sensor to gather electrical network three-phase voltage signal u _gabcand double fed induction generators stator three-phase voltage signal u _sabc;

A2) by the electrical network three-phase voltage signal u gathering _gabcafter digital phase-locked loop PLL, obtain electrical network positive sequence voltage electrical degree θ _g+and synchronous electric angular velocity omega;

A3) by the electrical network three-phase voltage signal u gathering _gabc, generator unit stator three-phase voltage signal u _sabcarrive the permanent power conversion of the static two-phase α β system of axis, voltage signal, i.e. u under the convert to static two-phase α β system of axis through the static three-phase abc system of axis respectively _{g α β}, u _{s α β};

A4) adopt electrical network positive sequence voltage oriented approach, by steps A 3 gained u _{g α β}through phase sequence separation module, extract respectively the lower line voltage fundamental positive sequence of forward synchronous angular velocity rotatable coordinate axis system the lower line voltage negative sequence component of reverse sync angular speed rotatable coordinate axis system line voltage 5 order harmonic components under 5 times of synchronous angular velocity reverse rotation systems of axis be rotated in the forward line voltage 7 order harmonic components under the system of axis with 7 times of synchronous angular velocities

A5) adopt electrical network positive sequence voltage oriented approach, by steps A 3 gained u _{s α β}after the permanent power conversion of forward synchronous angular velocity rotatable coordinate axis system, obtain stator voltage dq axle component under forward synchronous angular velocity rotatable coordinate axis system through the static two-phase α β system of axis

A6) under forward synchronous angular velocity rotatable coordinate axis system, steps A 4 is obtained obtain with steps A 5 both differences are sent into voltage controller and are regulated;

A7) the control voltage u using the output of steps A 6 voltage controllers as series connection grid side converter inhibition stator negative phase-sequence and harmonic voltage _seriesdq;

A8) series connection grid side converter control voltage u steps A 7 being obtained _seriesdqbe tied to the permanent power conversion of the static two-phase α β system of axis through forward synchronous angular velocity rotatable coordinate axis, can obtain controlling voltage u under the static two-phase α β system of axis _{series α β};

A9) by the series connection grid side converter control voltage u of steps A 8 gained _{series α β}with DC voltage U _dcproduce series connection grid side converter PWM by space vector modulation and drive signal;

The control step of described parallel-connection network side converter is:

B1) utilize voltage hall sensor to gather electrical network three-phase voltage signal u _gabc, current Hall transducer gathers double fed induction generators stator three-phase current signal i _sabcand the three-phase current signal i of parallel-connection network side converter _gabc;

B2) utilize voltage hall sensor to gather DC voltage signal U _dc;

The three-phase current signal of the electrical network three-phase voltage signal B3) B1 being gathered and double fed induction generators stator, parallel-connection network side converter is respectively after the static three-phase abc system of axis arrives the permanent power conversion of the static two-phase α β system of axis, voltage, current signal under the convert to static two-phase α β system of axis, i.e. u _{g α β}, i _{s α β}, i _{g α β};

B4) u step B3 being obtained _{g α β}, i _{s α β}, i _{g α β}after the permanent power conversion that through the static two-phase α β system of axis to forward synchronous angular velocity rotatable coordinate axis is respectively, obtain line voltage and stator, parallel-connection network side converter current dq axle component under forward synchronous angular velocity rotatable coordinate axis system

B5) DC bus-bar voltage of parallel-connection network side converter regulates and adopts pi regulator control, its adjuster output and DC bus-bar voltage set-point form DC bus-bar voltage average active power set-point computing formula is

$P_{g\_\mathrm{av}}^{*}=(K_{\mathrm{pu}}+K_{\mathrm{iu}}/s)(U_{\mathrm{dc}}^{*}-U_{\mathrm{dc}})\·U_{\mathrm{dc}}^{*}$

Wherein: represent that parallel-connection network side converter maintains DC bus-bar voltage and stablizes required average active power instruction, for DC bus-bar voltage set-point, K _puand K _iube respectively DC bus-bar voltage adjuster proportionality coefficient and integral coefficient;

B6) parallel-connection network side converter using positive sequence line voltage is oriented to d axle, by steps A 4, B4, B5 gained send into parallel-connection network side converter reference current command calculations module, obtain under forward synchronous angular velocity rotatable coordinate axis system and comprise fundamental positive sequence, negative phase-sequence and harmonic components in interior parallel-connection network side converter reference current instruction

B7) by step B6 gained with B4 gained difference send into current controller and regulate, current controller is output as

B8) obtain according to step B4, B6 and the output of step B7 current controller calculate parallel-connection network side convertor controls voltage

B9) by B8 gained parallel-connection network side convertor controls voltage be tied to the permanent power conversion of the static two-phase α β system of axis through forward synchronous angular velocity rotatable coordinate axis, can obtain controlling voltage u under the static two-phase α β system of axis _{c α β};

B10) by the parallel-connection network side convertor controls voltage u of step B9 gained _{c α β}with DC voltage U _dcproduce parallel-connection network side converter PWM by space vector modulation and drive signal;

The control strategy of motor side converter

(C1) motor side converter using conventional vector control strategy, it controls voltage and DC voltage U _dcproduce motor side converter PWM by space vector modulation and drive signal.

2. the total active power of output of the double-fed induction wind power system fluctuation inhibition method that adopts series connection grid side converter under imbalance according to claim 1 and harmonic distortion line voltage, is characterized in that described steps A 4) comprise following sub-step:

A4.1) by u _{g α β}permanent power conversion through the static two-phase α β system of axis to forward synchronous angular velocity rotatable coordinate axis system, then after 2 ω, 6 ω trapper filtering, obtain line voltage positive sequence component dq axle component under forward synchronous angular velocity rotatable coordinate axis system

A4.2) by u _{g α β}permanent power conversion through the static two-phase α β system of axis to reverse sync angular speed rotatable coordinate axis system, then after 2 ω, 4 ω, 8 ω trapper filtering, obtain line voltage negative sequence component dq axle component under reverse sync angular speed rotatable coordinate axis system

A4.3) by u _{g α β}through the permanent power conversion of the static two-phase α β system of axis to the 5 times synchronous angular velocity reverse rotation system of axis, then after 4 ω, 6 ω, 12 ω trapper filtering, obtain line voltage 5 order harmonic components dq axle component under 5 times of synchronous angular velocity reverse rotation systems of axis

A4.4) by u _{g α β}be rotated in the forward the permanent power conversion of the system of axis through the static two-phase α β system of axis to 7 times synchronous angular velocity, then after 6 ω, 8 ω, 12 ω trapper filtering, obtain line voltage 7 order harmonic components and be rotated in the forward dq axle component under the system of axis 7 times of synchronous angular velocities

3. under imbalance according to claim 1 and harmonic distortion line voltage, adopt the total active power of output fluctuation of the double-fed induction wind power system inhibition method of series connection grid side converter, it is characterized in that, steps A 6) described voltage controller adds that by a traditional PI adjuster resonant regulator that two resonance frequencys are respectively 2 times, 6 times mains frequencies combines, its transfer function is:

$C_{\mathrm{uPI}-\mathrm{DFR}}\left(s\right)=K_{\mathrm{up}}+\frac{K_{\mathrm{ui}}}{s}+\frac{s{K}_{\mathrm{ur}1}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ur}2}}{s^2+{\mathrm{\ω}}_{\mathrm{cu}2}s+{(\±6\mathrm{\ω})}^2}$

C in formula _uPI-DFR(s) be the transfer function of voltage controller; K _up+, K _uibe respectively proportionality coefficient, the integral coefficient of voltage controller; K _ur1, K _ur2be respectively the resonance coefficient of two resonant regulators; ω _cu1, ω _cu2be respectively the cut-off frequency of two resonant regulators; ω is synchronous electric angular speed; S refers to complex variable.

4. the total active power of output fluctuation of the double-fed induction wind power system inhibition method that adopts series connection grid side converter under imbalance according to claim 1 and harmonic distortion line voltage, is characterized in that described step B6) comprise the following steps:

B6.1) calculate parallel-connection network side converter fundamental positive sequence, negative-sequence current reference instruction:

$i_{\mathrm{gd}+}^{+*}=\frac{u_{\mathrm{gd}+}^{+}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gq}-}^{-}\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+2}-u_{g-}^{-2}}$

$i_{\mathrm{gq}+}^{+*}=-\frac{u_{\mathrm{gd}+}^{+}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}+\frac{u_{\mathrm{gq}-}^{-}\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+2}+u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+2}+u_{g-}^{-2}}$

$i_{\mathrm{gd}-}^{-*}=\frac{k_1\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+4}-u_{g-}^{-4}}+\frac{k_2\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+4}-u_{g-}^{-4}}-\frac{u_{\mathrm{gd}-}^{-}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}+\frac{u_{\mathrm{gq}-}^{-}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}$

$i_{\mathrm{gq}-}^{-*}=\frac{k_2\·P_{\mathrm{series}\_\cos 2}}{u_{g+}^{+4}-u_{g-}^{-4}}+\frac{k_3\·P_{\mathrm{series}\_\sin 2}}{u_{g+}^{+4}-u_{g-}^{-4}}-\frac{u_{\mathrm{gq}-}^{-}\·P_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}-u_{g-}^{-2}}-\frac{u_{\mathrm{gd}-}^{-}\·Q_{g\_\mathrm{av}}^{*}}{u_{g+}^{+2}+u_{g-}^{-2}}$

Wherein $\left\{\begin{array}{c}{k}_1=u_{\mathrm{gd}+}^{+3}-u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gq}-}^{-2}+u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-2}\\ k_2=2u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-}\·u_{\mathrm{gq}-}^{-}\\ k_3=u_{\mathrm{gd}+}^{+3}-u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gd}-}^{-2}+u_{\mathrm{gd}+}^{+}\·u_{\mathrm{gq}-}^{-2}\\ P_{\mathrm{series}\_\cos 2}=-u_{\mathrm{gd}-}^{-}{i}_{\mathrm{sd}+}^{+}-u_{\mathrm{gq}-}^{-}{i}_{\mathrm{sq}+}^{+}\\ P_{\mathrm{series}\_\sin 2}=-u_{\mathrm{gq}-}^{-}{i}_{\mathrm{sd}+}^{+}+u_{\mathrm{gd}-}^{-}{i}_{\mathrm{sq}+}^{+}\end{array}\right.$

set according to the reactive requirement of electrical network;

B6.2) calculating parallel-connection network side converter 5 times, 7 subharmonic current reference instructions are:

$\begin{array}{c}{i}_{\mathrm{gd}5-}^{\text{5-*}}=((P_{\mathrm{series}\_\cos 6}-(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gq}+}^{+*})\\ +(-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}7+}^{7+}-u_{\mathrm{gq}5-}^{5-})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gq}5-}^{\text{5-*}}=((P_{\mathrm{series}\_\sin 6}-(u_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gq}+}^{+*})\\ -(-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}+(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gd}7+}^{\text{7+*}}=((P_{\mathrm{series}\_\cos 6}-(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gq}+}^{+*})\\ -(-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gq}7+}^{7+}-u_{\mathrm{gq}5-}^{5-})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

$\begin{array}{c}{i}_{\mathrm{gq}7+}^{\text{7+*}}=-((P_{\mathrm{series}\_\sin 6}-(u_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}-(u_{\mathrm{gd}7+}^{7+}-u_{\mathrm{gd}5-}^{5-})i_{\mathrm{gq}+}^{+*})\\ +(-(u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{gd}+}^{+*}+(u_{\mathrm{gd}5-}^{5-}+u_{\mathrm{gd}7+}^{7+})i_{\mathrm{gq}+}^{+*}))/\left(2u_{\mathrm{gd}+}^{+}\right)\end{array}$

Wherein $\left\{\begin{array}{c}{P}_{\mathrm{series}\_\cos 6}=({-u}_{\mathrm{gd}5-}^{5-}-u_{\mathrm{gd}7+}^{7+})i_{\mathrm{sd}+}^{+}+({-u}_{\mathrm{gq}5-}^{5-}-u_{\mathrm{gq}7+}^{7+})i_{\mathrm{sq}+}^{+}\\ P_{\mathrm{series}\_\sin 6}=(-u_{\mathrm{gq}5-}^{5-}+u_{\mathrm{gq}7+}^{7+})i_{\mathrm{sd}+}^{+}+(u_{\mathrm{gd}5-}^{5-}-u_{\mathrm{gd}7+}^{7+})i_{\mathrm{sq}+}^{+}\end{array}\right.;$

B6.3) by the parallel-connection network side converter negative phase-sequence calculating, 5 times, 7 subharmonic current instructions, that is: being rotated in the forward the system of axis through reverse sync angular speed rotatable coordinate axis system, 5 times of synchronous angular velocity reverse rotation systems of axis, 7 times of synchronous angular velocities is respectively permanent power conversion to forward synchronous angular velocity rotatable coordinate axis, can obtain respectively the lower parallel-connection network side converter negative phase-sequence of forward synchronous angular velocity rotatable coordinate axis system, 5 times, 7 subharmonic current set-points again will with parallel-connection network side converter fundamental positive sequence current-order be added, can obtain the current-order of the lower parallel-connection network side converter of forward synchronous angular velocity rotatable coordinate axis system that is:

$i_{\mathrm{gdq}}^{+*}=i_{\mathrm{gdq}+}^{+*}+i_{\mathrm{gdq}-}^{+*}+i_{\mathrm{gdq}5-}^{+*}+i_{\mathrm{gdq}7+}^{+*}=i_{\mathrm{gdq}+}^{+*}+i_{\mathrm{gdq}-}^{-*}{e}^{-j2{\mathrm{\θ}}_g}+i_{\mathrm{gdq}5-}^{5-*}{e}^{-j6{\mathrm{\θ}}_g}+i_{\mathrm{gdq}7+}^{7+*}{e}^{j6{\mathrm{\θ}}_g}.$

5. under imbalance according to claim 1 and harmonic distortion line voltage, adopt the total active power of output fluctuation of the double-fed induction wind power system inhibition method of series connection grid side converter, it is characterized in that, step B7) described current controller adds that by a traditional PI adjuster resonant regulator that two resonance frequencys are respectively 2 times, 6 times mains frequencies combines, its transfer function is:

$C_{\mathrm{iPI}-\mathrm{DFR}}\left(s\right)=K_{\mathrm{ip}}+\frac{K_{\mathrm{ii}}}{s}+\frac{s{K}_{\mathrm{ir}1}}{s^2+{\mathrm{\ω}}_{\mathrm{ci}1}s+{(\±2\mathrm{\ω})}^2}+\frac{s{K}_{\mathrm{ir}2}}{s^2+{\mathrm{\ω}}_{\mathrm{ci}2}s+{(\±6\mathrm{\ω})}^2}$

C in formula _iPI-DFR(s) be the transfer function of current controller; K _ip, K _iibe respectively proportionality coefficient, the integral coefficient of current controller; K _ir1, K _ir2be respectively the resonance coefficient of two resonant regulators; ω _ci1, ω _ci2be respectively the cut-off frequency of two resonant regulators; ω is synchronous electric angular speed; S refers to complex variable.