CN104993521B - Energy storage method based on virtual synchronous inversion control - Google Patents

Abstract

The invention discloses a kind of energy storage method based on virtual synchronous inversion control, solve the problems, such as power electronics energy-storage system zero rotary inertia.Because converters system has zero moment of inertia characteristics, grid disturbances and frequency disturbance can cause to have a strong impact on to the control performance of energy-storage system, shorten the energy-storage system life-span, jeopardize power electronics energy storage device and power system security.The present invention adopts virtual synchronous electric machines control technology, making the external characteristics of the exchange interface of the energy storage device with power electronic system can be equivalent to synchronous motor characteristic, thus improving inertia and the damping characteristic of power electronics energy-storage system, strengthening the stability of power system.

Description

Energy storage method based on virtual synchronous inversion control

Technical field

The present invention relates to intelligent grid, particularly a kind of energy storage method based on virtual synchronous inversion control.

Background technology

Because power electronic equipment does not almost have rotary inertia and damping characteristic, consider energy-storage system from two kinds of angles The problem of discharge and recharge.

From the point of view of electrical network, set up and improve a kind of electrical network form intelligence more friendly to generation of electricity by new energy Electrical network, can solve the problems, such as generation of electricity by new energy well.Topmost two features of intelligent grid are exactly intelligent and big rule Mould utilizes regenerative resource.In following intelligent grid, AC network is as the main power transmission mode of power system, direct current transportation As the important useful supplement of ac transmission.Compared to AC network, direct current network is more friendly to generation of electricity by new energy.Small-sized The place concentrated of distributed power generation (referring mainly to wind-power electricity generation and photovoltaic generation) small-sized DC distribution net can be set up, finally It is incorporated to large-scale ac transmission network after unified inversion.Due to the access of extensive new forms of energy equipment, energy storage device is also following intelligence Can the indispensable necessaries of electrical network.Building intelligent grid is an essential measure solving new energy power generation grid-connection.

From the point of view of inverter, the transformation of AC network and development occur in that another kind of thinking.Traditional bulk power grid TRT (thermal power generation, hydroelectric generation etc.) be manufactured almost exclusively by synchronous generator generate electricity, if the inverter in distribution from Net side is looked and can be presented the operation characteristic of synchronous generator, then just can be well compatible with traditional electrical network.For this reason, it may be necessary to Inverter is transformed so as to assume the characteristic of synchronous generator as viewed from net side, thus the stability of electrical network of increasing exchanges.

Based on the virtual synchronous inversion controlling method of energy-storage system, according to the electromagnet inertia of synchronous generator, to inverter It is controlled, more can reflect the characteristic of synchronous generator.The electromagnetic property of synchronous generator is simulated, rotor is used in controller Property, primary frequency modulation and excitation voltage adjustment characteristic, more can simulate the characteristic of synchronous generator from external characteristics, and due to idle, have There is integral element in work(control section, can achieve that idle, active indifference controls, and can substantially improve system stability.

Content of the invention

It is an object of the invention to provide a kind of energy-storage system based on virtual synchronous inversion control and its control method, should When battery charges, inverter adopts the control strategy of virtual synchronous inversion transformation technique to system, can improve inertia and the damping of system Characteristic, the stability of strengthening system.

The technical solution of the present invention is as follows：

A kind of energy-storage system based on virtual synchronous inversion control, its feature is, comprise battery, DC/DC changer, DC/AC changer, transformator, AC network, the first controller and second controller；

Described battery is connected with the input of DC/DC changer, the described outfan of DC/DC changer with described The input of DC/AC changer is connected, and the outfan of this DC/AC changer is connected with the low pressure, input end of described transformator, The high-voltage output end of described transformator is connected with AC network；

The described outfan of the first controller is connected with the control end of described DC/DC changer, the first controller Input is connected with the outfan of DC/DC changer, the control of the described outfan of second controller and DC/AC changer End is connected, and the input of second controller is connected with the outfan of described DC/AC changer；

The first described controller includes first comparator and a PI controller, the output termination of this first comparator the The input of one PI controller；

Described second controller includes virtual synchronous inversion control, Power Control, current control, voltage coordinate modulus of conversion Block, electric current coordinate transferring and inverse coordinate transferring six part, described virtual synchronous inversion control part includes machinery Partly, excitation system, angular transition module and electric part；

Described mechanical part outfan connects the described input of angular transition module respectively and described inverse coordinate turns The input of die change block, the outfan of described angular transition module connects the input of described voltage coordinate modular converter respectively With the input of electric current coordinate transferring, the described electric part of the output termination of described voltage coordinate modular converter defeated Enter end, the output of described excitation system terminates the input of described electric part, and the output of described electric part terminates The input of described current control, the input of the described current control of the output termination of described Power Control, described electricity The input of the inverse coordinate transferring described in output termination of flow control；

The second comparator that described mechanical part includes being sequentially connected, the 3rd comparator, hypothetical rotor inertial element, One adder and first integrator, the outfan of described hypothetical rotor inertial element connects described second through tune difference feedback element Second input of comparator；

Described excitation system includes the 4th comparator, virtual magnetizing exciter and the first compensator, described virtual magnetizing exciter Outfan connect the second input of the 4th comparator through the first described compensator；

Described power control section is divided including the 5th comparator and the 2nd PI controller, the 6th comparator and the 3rd PI control Device；

Described current control division divides including the control of d axle component and the control of q axle component, and described d axle component controls inclusion Second adder, the 7th comparator and the 4th PI controller, described q axle component controls and includes the 3rd adder, the 8th compares Device and the 5th PI controller.

The first described controller and second controller are digital signal processor, single-chip microcomputer or computer.

Described DC/DC changer is high-power, wide output voltage range DC converter.

Described DC/AC changer is the Comprehensive Control being combined using virtual synchronous inversion control and conventional power control The direct current of algorithm becomes the changer of exchange, realizes whole energy-storage system is equivalent in terms of net side the mesh of a synchronous generator , the adaptively voltage of responsive electricity grid and frequency disturbance, the inertial properties of strengthening system and damping characteristic.

Using the control method of the described energy-storage system based on virtual synchronous inversion control, its feature is, the method Including following content and step：

1) initialize, in this energy-storage system, following parameter value is set according to system requirements by operator：

The DC bus-bar voltage reference value of DC/AC changer

Electromagnetic power reference value P of energy-storage system_ref；

Reactive power reference qref Q of energy-storage system_ref；

Set difference coefficient R as between 30-50, inertia constant M as between 1-20, load-damping constant D as 1% or 2%；

Set hypothetical rotor x_qImpedance x with stator_dIt is between 1-10；

AC voltage reference value U_ref, per unit value is set to 1；

Set the gain K of the first compensator of excitation system_fWith time constant T_fBetween 0-1, the gain K of excitation system_a Between 100-500, excitation system time constant T_eBetween 0-1, upper limit E of excitation voltage amplitude_fmax0-15 it Between, the lower limit E of excitation voltage amplitude_fmin=-E_fmax；

Set the hypothetical rotor transient state impedance x ' of electric part_dSpan between 0.1-0.5, the resistance of the transient state of stator Anti- x '_qSpan between 0.3-1, the transient state open circuit time constant T of d axle_d′_oSpan between 1.5-10, q axle Transient state open circuit time constant T '_qoSpan between 0.5-2.0；

The control coefrficient of the first PI controller is k_p1And k_i1, 0<k_p1<1000,0<k_i1<1000；

The control coefrficient of the 2nd PI controller is k_p2And k_i2, 0<k_p2<1000,0<k_i2<1000；

The control coefrficient of the 3rd PI controller is k_p3And k_i3, 0<k_p3<1000,0<k_i3<1000；

The control coefrficient of the 4th PI controller is k_p4And k_i4, 0<k_p4<1000,0<k_i4<1000；

The control coefrficient of the 5th PI controller is k_p5And k_i5, 0<k_p5<1000,0<k_i5<1000；

Using Hall element, DC voltage, AC voltage and current are sampled, obtain DC/DC changer (2) output end voltage U_dc, unit is per unit value, and grid side three-phase voltage e_a, e_b, e_cWith grid side three-phase current i_a, i_b, i_c；

2), the first controller executes according to the following steps：

21), first comparator calculates the input value of a PI controller：

22), a PI controller is calculated after the output receiving above-mentioned first comparator, and output is corresponding to be controlled Amount：

3) mechanical part of the virtual synchronous inversion control of second controller (7) executes according to the following steps：

31), following equation is pressed by the second comparator and calculate virtual machine power P_m：

Wherein, P_refIt is the electromagnetic power reference value setting, R is difference coefficient, Δ ω is hypothetical rotor offsetFor the output of hypothetical rotor inertial element, M is the inertia constant in hypothetical rotor inertial element, and D is void Intend the load-damping constant in rotor inertia link, s is complex frequency, the initial value of Δ ω is set to zero；

32), pass through virtual accelerating power P of the 3rd comparator calculating machine part_a：

P_a=P_m-P_e, wherein P_eFor the electromagnetic power of mechanical part, P_e=e_ai_a+e_bi_b+e_ci_c；

33), calculating angular velocity by first adder is：ω=ω₀+ Δ ω, ω₀For the initial value of angular velocity, work as electrical network Frequency is 50Hz, then ω₀=2 × π × 50=314rad/s；

34), synchronous angle is calculated by first integrator：θ=∫ ω；θ is the input of angular transition module；

35), angle compensation is carried out by angular transition module, formula is as follows：

Wherein, θ ' is lock phase angle；I is power network current amplitude；e_gFor grid voltage amplitude；x_qFor hypothetical rotor impedance；

4), the excitation system of second controller virtual synchronous inversion control executes according to the following steps：

41), pass through input quantity U that the 4th comparator calculates virtual magnetizing exciter_t, formula is as follows：

U_t=U_ref-U_x

Wherein：U_refFor the AC magnitude of voltage setting, K_fAnd T_fGain for the first compensator and time constant；U_xFor The output of one compensator；

42) the input virtual excitation voltage E of electric part, is calculated by virtual magnetizing exciter_f, formula is as follows：

Wherein：K_aAnd T_eIt is respectively gain and the time constant of virtual magnetizing exciter, E_fmaxAnd E_fminIt is respectively virtual magnetizing exciter Voltage magnitude upper and lower bound；

43), pass through the first compensator and calculate U_x, formula is as follows：

5), voltage coordinate conversion module and electric current coordinate transformation module execute according to the following steps：

51), by e_a、e_bAnd e_cCalculate line voltage d-q component U through voltage coordinate conversion module_dAnd U_q, formula is as follows：

52), by i_a、i_bAnd i_cCalculate line voltage d-q component i through electric current coordinate transformation module_dAnd i_q, formula is as follows：

6), the electric part of second controller virtual synchronous inversion control executes according to the following steps：

61), calculating current is with reference to I_dref1And I_qref1, formula is as follows：

Wherein：U_dAnd U_qIt is the d-q component of line voltage；I_dref1And I_qref1It is described DC/AC changer (3) output electricity The virtual stator current part of stream, E_fIt is virtual excitation voltage；

7), second controller Power Control part executes according to the following steps：

71) input of the 2nd PI controller, is calculated by the 5th comparator：P_ref-P_e；

72), the 2nd PI controller is controlled computing after the output receiving above-mentioned 5th comparator, and output is corresponding Controlled quentity controlled variable I_dref2：I_dref2=k_p2(P_ref-P_e)+k_i2∫(P_ref-P_e)dt；It is the input of current control part；

73) input of the 3rd PI controller, is calculated by the 6th comparator：Q_ref-Q_e；

74), the 3rd PI controller is controlled computing after the output receiving above-mentioned 6th comparator, and output is corresponding Controlled quentity controlled variable I_qref2：

I_qref2=k_p3(Q_ref-Q_e)+k_i3∫(Q_ref-Q_e)dt；It is the input of current control part；

8), the d axle component of second controller (7) current control part controls and executes according to the following steps：

81), calculate d shaft current reference value I_dref, formula is as follows：

I_dref=I_dref1+I_dref2；

82) input of the 4th PI controller, is calculated by the 7th comparator：I_dref-I_d；I_dDivide for three-phase current d axle Amount, by i_a、i_bAnd i_cThrough coordinate transform output；

83), the 4th PI controller is controlled computing after the output receiving above-mentioned 7th comparator, and output is corresponding Obtain controlled quentity controlled variable U_dref：U_dref=k_p4(I_dref-I_d)+k_i4∫(I_dref-I_d)dt；

9), the q axle component of second controller current control part controls and executes according to the following steps：

91), calculate q shaft current reference value I_qref, formula is as follows：

I_qref=I_qref1+I_qref2；

92) input of the 5th PI controller, is calculated by the 8th comparator：I_qref-I_q；I_qDivide for three-phase current q axle Amount, by i_a、i_bAnd i_cThrough coordinate transform output；

93), the 5th PI controller is controlled computing after the output receiving above-mentioned 8th comparator, and output is mutually deserved Controlled quentity controlled variable U_qref：U_qref=k_p5(I_qref-I_q)+k_i5∫(I_qref-I_q)dt；

10), second controller output：

101), by the U being obtained_drefAnd U_qrefThrough the conversion of inverse coordinate transformation module, obtain U_aref、U_brefAnd U_crefThree tune Ripple processed, using these three amounts as control signal with carrier wave ratio relatively, obtains the control signal of DC/AC changer (3), and formula is as follows：

The technique effect of the present invention is as follows：

In present system, and the DC/AC inverter of grid side connection adopts the control method of virtual synchronous inversion transformation technique, Support and voltage support to the necessary frequency of electrical network, improve the stability of system.Its feature is as follows：

1st, because the external characteristics that power electronic system exchanges interface is equivalent to synchronous generator characteristic so that accumulator charge and discharge Electrical interface equipment can participate in electrical network interaction, provide necessary support to line voltage and frequency, can improve grid stability.

2., using having high power transmission ability, wide output voltage range DC/DC changer, the sound of system can be improved Answer speed and control accuracy.

Brief description

Fig. 1 is the entire block diagram of the energy-storage system based on virtual synchronous inversion transformation technique for the present invention.

Fig. 2 is virtual synchronous inversion control entirety control block diagram.

Fig. 3 is mechanical part control block diagram.

Fig. 4 is Excitation Controller block diagram.

Fig. 5 is the first controller control block diagram.

Fig. 6 is second controller Power Control block diagram.

Fig. 7 is second controller current control block diagram.

Fig. 8 is angular transition module

Fig. 9 is system control process figure.

Specific embodiment

With reference to embodiment and accompanying drawing, the invention will be further described, and nitrogen should not limit the protection model of the present invention with this Enclose.

Refer to Fig. 1, Fig. 1 be the energy-storage system schematic diagram based on virtual synchronous inversion transformation technique for the present invention, comprise battery 1, DC/DC changer 2, DC/AC changer 3, transformator 4, AC network 5, the first controller 6 and second controller 7, in detailed below Introduce each ingredient：

Described battery 1 is to provide energy stores and the equipment of energy output for energy-storage system；

DC/DC changer 2 is high-power, wide output voltage range changer；

DC/AC changer 3 controls, using the control method of virtual synchronous inversion transformation technique and conventional power, the synthesis combining Control algolithm, realizes whole energy-storage system is equivalent in terms of net side the purpose of a synchronous generator, adaptively responds electricity The voltage of net and frequency disturbance, the inertial properties of strengthening system and damping characteristic.

First controller 6 is responsible for sampling, process, calculating and control of DC/DC changer 2 etc.；

Second controller 7 is responsible for data sampling, process, calculating and control etc., and the DC/AC changer 3 of net side is controlled System.

Described battery 1 is connected with the input of DC/DC changer 2, the described outfan of DC/DC changer 2 and institute The input of the DC/AC changer 3 stated is connected, the low pressure input of the outfan of this DC/AC changer 3 and described transformator 4 End is connected, and the described high-voltage output end of transformator 4 is connected with AC network 5；

The described outfan of the first controller 6 is connected with the control end of described DC/DC changer 2, the first controller 6 Input be connected with the outfan of DC/DC changer 2, the described outfan of second controller 7 and DC/AC changer 3 Control end is connected, and the input of second controller 7 is connected with the outfan of described DC/AC changer 3.

Fig. 2 is the control block diagram of the first controller 6, and the first described controller 6 includes first comparator and PI control Device processed, the input of output termination the first PI controller of this first comparator.

Described second controller 7 includes virtual synchronous inversion control, Power Control, current control, voltage coordinate conversion Module, electric current coordinate transferring and inverse coordinate transferring six part, described virtual synchronous inversion control part includes machine Tool part, excitation system, angular transition module and electric part；

Described mechanical part outfan connects the described input of angular transition module respectively and described inverse coordinate turns The input of die change block, the outfan of described angular transition module connects the input of described voltage coordinate modular converter respectively With the input of electric current coordinate transferring, the described electric part of the output termination of described voltage coordinate modular converter defeated Enter end, the output of described excitation system terminates the input of described electric part, and the output of described electric part terminates The input of described current control, the input of the described current control of the output termination of described Power Control, described electricity The input of the inverse coordinate transferring described in output termination of flow control；

The second comparator that described mechanical part includes being sequentially connected, the 3rd comparator, hypothetical rotor inertial element, One adder and first integrator, the outfan of described hypothetical rotor inertial element connects described second through tune difference feedback element Second input of comparator；

Described excitation system includes the 4th comparator, virtual magnetizing exciter and the first compensator, described virtual magnetizing exciter Outfan connect the second input of the 4th comparator through the first described compensator；

Described power control section is divided including the 5th comparator and the 2nd PI controller, the 6th comparator and the 3rd PI control Device；

Described current control division divides including the control of d axle component and the control of q axle component, and described d axle component controls inclusion Second adder, the 7th comparator and the 4th PI controller, described q axle component controls and includes the 3rd adder, the 8th compares Device and the 5th PI controller.

Fig. 3 is virtual synchronous inversion control entirety control block diagram, and Fig. 4 is mechanical part control block diagram, and Fig. 5 is virtual synchronous The exciter control system of inversion controlling method, Fig. 6 is the Power Control block diagram of second controller 7, and Fig. 7 is the electricity of second controller Flow control block diagram, Fig. 8 is angular transition module diagram, and Fig. 9 is the overall control flow chart of present system.Fig. 4, Fig. 5, figure 6 and Fig. 7 are included in Fig. 3.

Claims (1)

1. a kind of energy storage method based on virtual synchronous inversion control is it is characterised in that the method comprises the steps：

Step 1) initialization, in this energy-storage system, following parameter value is set according to system requirements by operator：

The DC bus-bar voltage reference value of DC/AC changer

Electromagnetic power reference value P of energy-storage system_ref；

Reactive power reference qref Q of energy-storage system_ref；

Set difference coefficient R as between 30-50, inertia constant M as between 1-20, load-damping constant D is as 1% or 2%；

Set hypothetical rotor x_qImpedance x with stator_dIt is between 1-10；

AC voltage reference value U_ref, per unit value is set to 1；

Set the gain K of the first compensator of excitation system_fWith time constant T_fBetween 0-1, the gain K of excitation system_a? Between 100-500, excitation system time constant T_eBetween 0-1, upper limit E of excitation voltage amplitude_fmaxBetween 0-15, The lower limit E of excitation voltage amplitude_fmin=-E_fmax；

Set the hypothetical rotor transient state impedance x ' of electric part_dSpan between 0.1-0.5, the transient state impedance x ' of stator_q Span between 0.3-1, the transient state open circuit time constant T ' of d axle_doSpan between 1.5-10, q axle temporary State open circuit time constant T '_qoSpan between 0.5-2.0；

The control coefrficient of the first PI controller is k_p1And k_i1, 0<k_p1<1000,0<k_i1<1000；

The control coefrficient of the 2nd PI controller is k_p2And k_i2, 0<k_p2<1000,0<k_i2<1000；

The control coefrficient of the 3rd PI controller is k_p3And k_i3, 0<k_p3<1000,0<k_i3<1000；

The control coefrficient of the 4th PI controller is k_p4And k_i4, 0<k_p4<1000,0<k_i4<1000；

The control coefrficient of the 5th PI controller is k_p5And k_i5, 0<k_p5<1000,0<k_i5<1000；

Using Hall element, DC voltage, AC voltage and current are sampled, obtain DC/DC changer (2) Output end voltage U_dc, unit is per unit value, and grid side three-phase voltage e_a, e_b, e_cWith grid side three-phase current i_a, i_b, i_c；

Step 2), the first controller executes according to the following steps：

21), first comparator calculates the input value of a PI controller：

22), a PI controller is calculated after the output receiving above-mentioned first comparator, exports corresponding controlled quentity controlled variable：

Step 3) mechanical part of virtual synchronous inversion control of second controller (7) executes according to the following steps：

31), following equation is pressed by the second comparator and calculate virtual machine power P_m：

$P_m=P_{ref}-\frac{1}{R}\mathrm{\&Delta;}\mathrm{\&omega;},$

Wherein, P_refIt is the electromagnetic power reference value setting, R is difference coefficient, Δ ω is hypothetical rotor offsetFor the output of hypothetical rotor inertial element, M is the inertia constant in hypothetical rotor inertial element, and D is void Intend the load-damping constant in rotor inertia link, s is complex frequency, the initial value of Δ ω is set to zero；

32), pass through virtual accelerating power P of the 3rd comparator calculating machine part_a：

P_a=P_m-P_e, wherein P_eFor the electromagnetic power of mechanical part, P_e=e_ai_a+e_bi_b+e_ci_c；

33), calculating angular velocity by first adder is：ω=ω₀+ Δ ω, ω₀For the initial value of angular velocity, work as mains frequency For 50Hz, then ω₀=2 × π × 50=314rad/s；

34), synchronous angle is calculated by first integrator：θ=∫ ω；θ is the input of angular transition module；

35), angle compensation is carried out by angular transition module, formula is as follows：

$tan\left({\mathrm{\&theta;}}_0\right)=\frac{x_{q}I}{e_g}$

${\mathrm{\&theta;}}^{\&prime;}=\mathrm{\&theta;}-(\frac{\mathrm{\&pi;}}{2}-{\mathrm{\&theta;}}_0)$

Wherein, θ ' is lock phase angle；I is power network current amplitude；e_gFor grid voltage amplitude；x_qFor hypothetical rotor impedance；

Step 4), the excitation system of second controller virtual synchronous inversion control executes according to the following steps：

41), pass through input quantity U that the 4th comparator calculates virtual magnetizing exciter_t, formula is as follows：

U_t=U_ref-U_x

Wherein：U_refFor the AC magnitude of voltage setting, K_fAnd T_fGain for the first compensator and time constant；U_xFor the first benefit Repay the output of device；

42) the input virtual excitation voltage E of electric part, is calculated by virtual magnetizing exciter_f, formula is as follows：

$E_f=\frac{K_a}{T_{e}s+1}{U}_t,$

Wherein：K_aAnd T_eIt is respectively gain and the time constant of virtual magnetizing exciter, E_fmaxAnd E_fminIt is respectively the electricity of virtual magnetizing exciter The upper and lower bound of pressure amplitude value；

43), pass through the first compensator and calculate U_x, formula is as follows：

$U_x=\frac{{\mathrm{sK}}_f}{T_{f}s+1}{E}_f.$

Step 5), voltage coordinate conversion module and electric current coordinate transformation module execute according to the following steps：

51), by e_a、e_bAnd e_cCalculate line voltage d-q component U through voltage coordinate conversion module_dAnd U_q, formula is as follows：

$\left[\begin{array}{c}{U}_d\\ U_q\end{array}\right]=\frac{\sqrt{2}}{\sqrt{3}}\left[\begin{array}{ccc}\cos \mathrm{\&theta;}& \cos (\mathrm{\&theta;}-\frac{2}{3}\mathrm{\&pi;})& \cos (\mathrm{\&theta;}+\frac{2}{3}\mathrm{\&pi;}\\ -\sin \mathrm{\&theta;}& -\sin (\mathrm{\&theta;}-\frac{2}{3}\mathrm{\&pi;})& -\sin (\mathrm{\&theta;}+\frac{2}{3}\mathrm{\&pi;})\end{array}\right]\left[\begin{array}{c}{e}_a\\ e_b\\ e_c\end{array}\right]$

52), by i_a、i_bAnd i_cCalculate line voltage d-q component i through electric current coordinate transformation module_dAnd i_q, formula is as follows：

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\frac{\sqrt{2}}{\sqrt{3}}\left[\begin{array}{ccc}\cos \mathrm{\&theta;}& \cos (\mathrm{\&theta;}-\frac{2}{3}\mathrm{\&pi;})& \cos (\mathrm{\&theta;}+\frac{2}{3}\mathrm{\&pi;}\\ -\sin \mathrm{\&theta;}& -\sin (\mathrm{\&theta;}-\frac{2}{3}\mathrm{\&pi;})& -\sin (\mathrm{\&theta;}+\frac{2}{3}\mathrm{\&pi;})\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

Step 6), the electric part of second controller virtual synchronous inversion control executes according to the following steps：

61), calculating current is with reference to I_dref1And I_qref1, formula is as follows：

$I_{dref1}=\frac{E_f-(T_{d0}^{\&prime;}s+1)U_q}{x_d^{\&prime;}{T}_{d0}^{\&prime;}s+x_d}$

$I_{qref1}=\frac{(T_{q0}^{\&prime;}s+1)U_d}{x_q^{\&prime;}{T}_{q0}^{\&prime;}s+x_q}$

Wherein：U_dAnd U_qIt is the d-q component of line voltage；I_dref1And I_qref1It is described DC/AC changer (3) output current Virtual stator current part, E_fIt is virtual excitation voltage；

Step 7), second controller Power Control part executes according to the following steps：

71) input of the 2nd PI controller, is calculated by the 5th comparator：P_ref-P_e；

72), the 2nd PI controller is controlled computing after the output receiving above-mentioned 5th comparator, and output is corresponding to be controlled Amount I_dref2：I_dref2=k_p2(P_ref-P_e)+k_i2∫(P_ref-P_e)dt；It is the input of current control part；

73) input of the 3rd PI controller, is calculated by the 6th comparator：Q_ref-Q_e, Q_eIdle work(for energy-storage system output Rate；

74), the 3rd PI controller is controlled computing after the output receiving above-mentioned 6th comparator, and output is corresponding to be controlled Amount I_qref2：

I_qref2=k_p3(Q_ref-Q_e)+k_i3∫(Q_ref-Q_e)dt；It is the input of current control part；

Step 8), the d axle component of second controller (7) current control part controls and executes according to the following steps：

81), calculate d shaft current reference value I_dref, formula is as follows：

I_dref=I_dref1+I_dref2；

82) input of the 4th PI controller, is calculated by the 7th comparator：I_dref-I_d；I_dFor three-phase current d axle component, By i_a、i_bAnd i_cThrough coordinate transform output；

83), the 4th PI controller is controlled computing after the output receiving above-mentioned 7th comparator, exports mutually deserved control Amount U processed_dref：U_dref=k_p4(I_dref-I_d)+k_i4∫(I_dref-I_d)dt；

Step 9), the q axle component of second controller current control part controls and executes according to the following steps：

91), calculate q shaft current reference value I_qref, formula is as follows：

I_qref=I_qref1+I_qref2；

92) input of the 5th PI controller, is calculated by the 8th comparator：I_qref-I_q；I_qFor three-phase current q axle component, by i_a、i_bAnd i_cThrough coordinate transform output；

93), the 5th PI controller is controlled computing after the output receiving above-mentioned 8th comparator, exports mutually deserved control Amount U_qref：U_qref=k_p5(I_qref-I_q)+k_i5∫(I_qref-I_q)dt；

Step 10), second controller output：

101), by the U being obtained_drefAnd U_qrefThrough the conversion of inverse coordinate transformation module, obtain U_aref、U_brefAnd U_crefThree modulation Ripple, using these three amounts as control signal with carrier wave ratio relatively, obtains the control signal of DC/AC changer (3), and formula is as follows：

$\left[\begin{array}{c}{U}_{aref}\\ U_{bref}\\ U_{cref}\end{array}\right]=\frac{\sqrt{2}}{\sqrt{3}}\left(\begin{array}{cc}\cos \mathrm{\&theta;}& -\sin \mathrm{\&theta;}\\ \cos \left(\mathrm{\&theta;}-\frac{2}{3}\mathrm{\&pi;}\right)& -\sin \left(\mathrm{\&theta;}-\frac{2}{3}\mathrm{\&pi;}\right)\\ \cos \left(\mathrm{\&theta;}+\frac{2}{3}\mathrm{\&pi;}\right)& -\sin \left(\mathrm{\&theta;}+\frac{2}{3}\mathrm{\&pi;}\right)\end{array}\right)\left[\begin{array}{c}{U}_{dref}\\ U_{qref}\end{array}\right].$