CN104868762A - DES (distributed energy storage) power electronic transformer, and control method therefor - Google Patents

Abstract

The invention relates to a DES (distributed energy storage) power electronic transformer, and a control method therefor. The transformer comprises a power unit and an output module, wherein the power unit comprise an H bridge module, an energy storage module, and an isolation module. The energy storage module comprises a Buck-Boost converter, a filter inductor, and a storage battery. The storage battery is connected with the Buck-Boost converter through the filter inductor. According to the invention, the transformer employs the DES technology, guarantees enough energy under special working conditions, saves a large-capacity battery, and improves the operation stability. The energy storage battery employs an IAI interface, and achieves the decoupling of active power with DC side energy.

Description

A kind of electric power electric transformer and control method thereof of disperseing energy storage

Background technology

Along with network system development, traditional power transformer manifests some shortcomings gradually, as: when load is excessive, output voltage can be caused to decline, produce harmonic wave; Be no matter former side or pair side when breaking down, opposite side all can be affected; Function singleness, does not have the functions such as voltage-regulation, power factor correction and power flow control.

Electric power electric transformer (Power Electronic Transformer, PET) progressively grows up along with the development of semiconductor technology in recent years novelpower transformer, it takes full advantage of the advantage of current transformer and high frequency transformer, overcome the shortcoming of traditional transformer, Fault Isolation can also be realized, utility power quality control, the functions such as distributed DC power access, meet the demand that the initiatively modern intelligent grid such as electrical network and microgrid is built, development rapidly.But it can not bucking voltage interrupt, also helpless to degree of depth Voltage Drop.Electric power electric transformer is as the interface of major network and the subordinate such as active distribution network or microgrid electrical network, and when bad working environments appears in major network, such as voltage fluctuates widely or falls, and needs to ensure that subordinate's electrical network steadily can spend unusual service condition; When major network breaks down suddenly, need to ensure that subordinate's electrical network can be smooth in network operation.During major network non-normal working, ensure that subordinate's electrical network normally works, electric power electric transformer not only needs the controlling functions of high dynamic response, also needs enough energy supports.For the energy storage demand of electric power electric transformer, domesticly expand research gradually, and propose some energy storage methods.

Prior art is the low-voltage direct bus utilizing electric power electric transformer, bus accesses super capacitor energy-storage system, use DC/DC power conversion circuit between energy-storage system and bus, control accordingly, realize the discharge and recharge between super capacitor and DC bus.The shortcoming of prior art: (1) super capacitor concentrates energy storage, energy density is less than general energy-storage battery; (2) add extra DC/DC power conversion circuit between energy-storage system and electric power electric transformer, need two cover control system, and cost is high.(3) isolation level adopts full bridge structure, and switch tube voltage stress is difficult to balance, and electric current and voltage control capability are not strong.

Summary of the invention

In order to overcome the deficiencies in the prior art, a kind of energy-storage units by dispersion is the object of the present invention is to provide to realize the electric power electric transformer of energy storage.The present invention can ensure the energy support that electric power electric transformer is enough under special operation condition, and avoids the use of high capacity cell.

In order to realize object of the present invention, technical scheme of the present invention is as follows:

Disperse an electric power electric transformer for energy storage, it is characterized in that: described electric power electric transformer comprises cascade rectifier level, dispersion energy storage stage, isolation level, output stage;

Wherein, each phase of the input of described electric power electric transformer all accesses the input of H bridge module, and the output of H bridge module is connected with the input of corresponding energy-storage module, and the output of energy-storage module is connected with the input of corresponding isolation level; Described H bridge module, the energy-storage module corresponding to H bridge module and the isolation module corresponding with energy-storage module form power cell; On each of electric power electric transformer is single-phase, access n power cell and an output module, the input of H bridge module is as the input of power cell, and the input of power cell is connected with electrical network, and mutually, cascade connects, alternate Y-connection; The output of isolation module is the output of power cell, and the output of power cell is in parallel, is connected with the input of output module;

All H bridge modules on each is single-phase form this single-phase on cascade rectifier level, all energy-storage modules on each is single-phase form this single-phase on dispersion energy storage stage, all isolation modules on each is single-phase form this single-phase on isolation level, output stage is made up of an output module.

Described H bridge module is the controlled full bridge rectifier be made up of the IGBT of four band inverse parallel diodes.

Described energy-storage module comprises a Buck/Boost converter, filter inductance and storage battery, and storage battery is connected with buck/boost converter by filter inductance.

Described isolation module is bi-directional half bridge converter, and the both sides of bi-directional half bridge converter are symmetrical structure, and two, left and right half-bridge is connected by middle high frequency transformer.

Described output module is full-bridge DC/AC inverter.

Described dispersion energy storage stage controls the discharge and recharge of energy-storage battery, under main electrical network nominal situation, charges to energy-storage battery, until quantity of electric charge percentage SoC reaches rated value, enters poised state; Under poised state, control the balance of the energy-storage battery quantity of electric charge in a charging-discharging cycle; Main electrical network, when short time voltage is interrupted or the degree of depth falls, controls energy-storage battery electric discharge.

The rate-determining steps of cascade rectifier level comprises as follows:

Step S1: the virtual voltage of sampling cascade rectification stage every grade of H bridge module k represents phase (k ∈ a, b, c), and i represents progression (i ∈ 1 ~ n), asks for virtual voltage mean value v _dc;

Step S2: rectification stage every step voltage nominal reference component the virtual voltage mean value v of step (1) gained is deducted through subtracter _dc, obtain voltage error component Δ v _dc;

Step S3: voltage error component Δ v _dccurrent on line side direct current real component reference value is drawn after PI controller

Step S4: calculate power network current real component actual value i _sdwith idle component actual value i _sq;

Step S5: the step S3 current on line side direct current real component reference value obtained the power network current real component actual value i of step S4 gained is deducted through subtracter _sdobtain current on line side direct current real component margin of error Δ i _sd;

Step S6: current on line side direct current real component margin of error Δ i _sdby obtaining line voltage real component reference value after PI controller

Step S7: given power network current idle component reference value deduct the power network current idle component actual value i that step S4 obtains _sqobtain current on line side direct current reactive power error amount Δ i _sq;

Step S8: current on line side direct current reactive power error amount Δ i _sqby obtaining line voltage idle component reference value after PI controller

Step S9: the line voltage real component reference value that step (8) obtains with the line voltage idle component reference value obtained with step (10) three-phase modulations voltage is obtained after dq/abc conversion

Step S10: calculating voltage correction operand V ₀;

Step S11: the three-phase modulations voltage that step (11) is obtained deduct the voltage correction operand V that step (15) obtains respectively ₀try to achieve the modulation signal of every phase

Step S12: calculate every every grade H bridge submodule voltage and correct factor r _ki;

Step S13: by the modulation signal of every phase that step S11 obtains be multiplied by H bridge submodule voltage respectively and correct factor r _kitry to achieve the drive singal of each IGBT pipe

Described step S4 comprises:

Step S41: sampling line voltage obtains three-phase voltage value v _sa, v _sb, v _sc, sampling power network current obtains three-phase electricity flow valuve i _sa, i _sb, i _sc;

Step S42: by step (4) sampling gained line voltage v _sa, v _sb, v _sclock phase angle theta is obtained after genlock module;

Step S43: the current i that step (4) obtains _sa, i _sb, i _scthe lock phase angle theta obtained with step (5) tries to achieve power network current real component actual value i after abc/dq conversion _sdwith idle component actual value i _sq;

Described step S10 comprises:

Step S101: detect the every power P of rectification stage _a, P _b, P _c;

Step S102: according to formula try to achieve average power P _av;

Step S103: the every power P obtained by step (12) _a, P _b, P _crespectively divided by step (13) averaging of income power P _av, try to achieve every Power Correction Factor r _a, r _b, r _c;

Step S104: the three-phase modulations voltage that step (11) is tried to achieve with every Power Correction Factor r that step (14) is tried to achieve _a, r _b, r _cbring formula into $v_o=\frac{\max \{r_a\·v_{\mathrm{ca}}^{*},r_b\·v_{\mathrm{cb}}^{*},r_c\·v_{\mathrm{cc}}^{*}\}}{2}+\frac{\min \{r_a\·v_{\mathrm{ca}}^{*},r_b\·v_{\mathrm{cb}}^{*},r_c\·v_{\mathrm{cc}}^{*}\}}{2}$ In try to achieve voltage correction operand V ₀;

The circuit of described energy-storage battery discharge and recharge comprises a diverter switch, two adders, two subtracters, two proportional controllers, two integrators.

The process of the discharge and recharge of energy-storage battery comprises the steps:

Step (1): detection of grid working condition, network operation situation is divided into nominal situation and damage.Abnormal condition refers to that electric line voltage short interruptions or the voltage degree of depth are fallen;

Step (2): as working properly in step (1) detection of grid, then diverter switch is switched to charge mode.Electrical network charges a battery, and is charged to required rated value;

Step (3): as the interruption of step (1) detection of grid short time voltage or the voltage degree of depth are fallen, then diverter switch is switched to charge mode.Energy storage battery discharges, and maintains described transformer rated output power;

The described charging of step (2) controls, and detailed process is:

1.: energy-storage battery charging charge reference value energy-storage battery electric charge actual charge value SoC is deducted through subtracter _kidraw energy-storage battery charge error component Δ SoC _ki;

2.: energy-storage battery charge error component Δ SoC _kithe power back-off margin of error is drawn through proportional controller

3.: the power back-off margin of error with charge power superposition just obtains energy-storage battery actual charge value SoC after integrator _ki;

By above-mentioned quantity of electric charge outer shroud and a power inner ring double-closed-loop control, energy-storage battery is charged to required rated value;

Step (3) described control of discharge, detailed process is:

1. calculate electric power electric transformer power demand, obtain power command value

2. electric power electric transformer actual power value is deducted through subtracter draw the discharge power margin of error

3. the discharge power margin of error passing ratio controller draws energy-storage battery charge compensation margin of error Δ SoC _ki;

4. Δ SoC _kiwith energy-storage battery electric charge SoC _kielectric power electric transformer actual power value is obtained through integrator after superposition

By above-mentioned power outer shroud and quantity of electric charge inner ring double-closed-loop control, battery discharging, electric power electric transformer obtains required rated output power;

Above-mentioned SoC is electric charge percentage, and it characterizes the state of charge of energy-storage battery, for the nominal charge amount of energy-storage battery.

Isolation class control process comprises the steps:

Step (1). isolation level output current with output-current rating instruction current error signal Δ I is obtained through subtracter ₀;

Step (2). current error signal obtains duty cycle signals D through current controller ^ki;

Step (3). duty cycle signals D ^kiisolation level on high-tension side switching tube drive singal S is drawn through modulation _p;

Step (4). isolation level on high-tension side switching tube drive singal S _pthrough phase shift θ ^kidraw the drive singal S of low pressure side pipe _s;

Step (5). the switching signal S drawn _pand S _sthe switching tube work of driving isolation level.

Output class control process comprises the steps:

Step (1): output voltage DC component reference instruction value with output voltage DC component actual value voltage error signal is drawn through subtracter

Step (2): voltage error signal current signal is drawn through PI controller

Step (3): output voltage actual value be multiplied by ω _bc _fdraw couple current

Step (4): by load current DC component deduct the current signal of step (2) gained with the couple current of step (3) gained draw electric current loop reference instruction value

Step (5): by step (4) gained electric current loop reference instruction value with output current DC component actual value current error signal is drawn through subtracter

Step (6): current error signal voltage signal is drawn through PI controller

Step (7): output current actual value be multiplied by ω _bl _mdraw coupled voltages

Step (8): by output voltage DC component actual value deduct the voltage signal of step (6) gained with the coupled voltages of step (7) gained draw modulation voltage u _d;

Step (9): output voltage DC component reference instruction value with output voltage DC component actual value voltage error signal is drawn through subtracter

Step (10): voltage error signal current signal is drawn through PI controller

Step (11): output voltage actual value be multiplied by ω _bc _fdraw couple current

Step (12): by load current DC component deduct the current signal of step (10) gained with the coupled voltages of step (11) gained draw electric current loop reference instruction value

Step (13): by step (12) gained electric current loop reference instruction value with output current DC component actual value current error signal is drawn through subtracter

Step (14): current error signal voltage signal is drawn through PI controller

Step (15): output current actual value be multiplied by ω _bl _mdraw coupled voltages

Step (16): by output voltage DC component actual value deduct the voltage signal of step (14) gained with the coupled voltages of step (15) gained draw modulation voltage u _q;

Step (17): by step (8) gained modulation voltage u _dwith step (16) gained modulation voltage u _qafter dq/abc inverse transformation, produce drive singal, drive the work of inverter switching device pipe;

Described L _mfor inverter filtering inductance, C _ffor inverter filtering electric capacity, ω _bfor inverter output voltage angular frequency.

Operation principle of the present invention is: main grid alternating current carries out voltage rear with power control (power controls to comprise alternate power-balance and controls and interior cascaded H-bridges intermodule power-balance control mutually) by cascade rectifier level, obtains stable levitating type DC voltage wherein, k represents phase (k ∈ a, b, c), and i represents progression (i ∈ 1 ~ n), and the direct current total quantity of suspension is 3n.

Dispersion energy storage stage adopts IAI circuit access energy-storage battery, by the discharge and recharge of IAI control circui energy-storage battery, energy under guarantee major network damage needed for electric power electric transformer supports, the electric power electric transformer voltage fluctuation that also can cause due to power fluctuation as power buffer minimizing, charges to energy-storage battery under nominal situation.Meanwhile, by IAI Current Control, make energy-storage battery and the decoupling zero of DC side energy active power.The access of faling apart of 3n energy-storage battery component it also avoid the use of concentrated high capacity cell, decreases control difficulty.

The DHB structure of isolation level realizes the two-way flow of power at transformer high-voltage DC side (HV) and low-voltage direct side (LV) by phase shifting control, i.e. H2L pattern.Meanwhile, by resonant controller filtering two pulse wave, ensure that low current ripple exports, realize the thermal stress balance of switching device, current output capability is strengthened.

Output stage DC/AC full-bridge inverter uses the double-closed-loop control of inductive current inner ring and capacitance voltage outer shroud, and inductance here and electric capacity take from LC filter circuit.Inductive current inner ring can suppress load disturbance to affect fast, obtains good system dynamic response performance; Outer voltage can improve output voltage waveforms, improves output accuracy.

The beneficial effect that technical solution of the present invention is brought

(1) electric power electric transformer realizes energy storage, the energy support that under guarantee special operation condition, electric power electric transformer is enough.As the major network voltage degree of depth fall time, electric power electric transformer and subordinate's electrical network thereof still can stable operations.

(2) energy-storage battery dispersion access, avoids the use of high capacity cell.

(3) storage battery of dispersion access can cushion the fluctuation of electric power electric transformer internal power, stable DC side voltage.

(4) adopt IAI interface between rectification stage and energy-storage battery, achieve active power decoupling zero and more simply control.

(5) isolation level adopts half-bridge structure, and while realizing the two-way flow of power, balance cock tube voltage stress, improves the fan-out capability of electric power electric transformer.

Accompanying drawing explanation

figure1 overall topology of to disperse the electric power electric transformer preferred embodiment of energy storage for the present invention figure;

figure2 to disperse the power cell topological structure in the electric power electric transformer of energy storage for the present invention figure;

figure3 disperse the cascade rectifier level in the electric power electric transformer of energy storage to control for the present invention figure;

figure4 disperse the alternate power-balance in the electric power electric transformer of energy storage to control for the present invention figure;

figure5 for the present invention disperse in the electric power electric transformer of energy storage mutually in intermodule at different levels power-balance control figure;

figure6 to disperse the energy-storage battery charge and discharge control frame in the electric power electric transformer of energy storage for the present invention figure;

figure7 to disperse the isolation level controller chassis in the electric power electric transformer of energy storage for the present invention figure;

figure8 disperse the i-th grade of transformer both sides switch function phase shift signal mutually of kth in the electric power electric transformer of energy storage for the present invention figure;

figure9 to disperse the three-phase inverter uneoupled control in the electric power electric transformer of energy storage for the present invention figure.

Embodiment

Below in conjunction with attached figureand embodiment, the specific embodiment of the present invention is described further.Following examples only for clearer explanation technical scheme of the present invention, and can not limit the scope of the invention with this.

As figureshown in 1, a kind of electric power electric transformer of energy storage that disperses is made up of quaternary structure: cascade rectifier level, dispersion energy storage stage, isolation level and output stage.Every grade of specific embodiments is as follows:

(1) cascade rectifier level

Cascade rectifier level controller is made up of modules such as outer shroud voltage regulator, inner ring current tracking device, power governor, Phase-Locked Synchronous mechanisms, as figureshown in 3.Gather the direct voltage suspended, after calculating, obtain mean value v _dc, with reference voltage v _refrelatively and through PI regulate after, obtain meritorious reference current for ensureing the unity power factor of input current, idle reference current get zero.Inner ring current tracking device controls actual current to the quick tracking of instruction current, thus realizes the control of cascade rectifier level input current waveform and phase place.Inner ring current tracking device obtains command signal after controlling the phase signal that Phase-Locked Synchronous mechanism exports is for providing the reference phase needed for voltage vector oriented control and trigger impulse generation.

Due to DC voltage average value v _dcwith reference voltage more do not consider that the active power of each intermodule is uneven, for ensureing cascade rectifier level power-balance that is alternate and interior intermodule at different levels mutually, the modulation signal that current inner loop draws can't Direct driver switching tube, carry out power control.Concrete controller chassis figureas figure4, figure5.

First alternate power-balance detects each phase power P in controlling _a, P _b, P _c, obtain average power P _av, then balance cascade rectification stage three-phase alternating current side voltage by voltage correction computing, thus control the inflow power of three-phase synchronous.Wherein average power P _avwith voltage correction operand V ₀respectively as shown in formula 1 and formula 2.

$P_{\mathrm{av}}=\frac{P_a+P_b+P_c}{3}---\left(1\right)$

$v_o=\frac{\max \{r_a\·v_{\mathrm{ca}}^{*},r_b\·v_{\mathrm{cb}}^{*},r_c\·v_{\mathrm{cc}}^{*}\}}{2}+\frac{\min \{r_a\·v_{\mathrm{ca}}^{*},r_b\·v_{\mathrm{cb}}^{*},r_c\·v_{\mathrm{cc}}^{*}\}}{2}---\left(2\right)$

During phase internal power balance controls, after being compared with reference value by suspended voltage actual value at different levels, PI regulates and obtains DC voltage static difference compensation rate v _ki, then by introducing modular power at different levels in unit feed-forward voltage coefficient 1 equilibrium phase.

Concrete rate-determining steps is as follows:

Step (1): the virtual voltage of sampling cascade rectification stage every grade of H bridge module k represents phase (k ∈ a, b, c), and i represents progression (i ∈ 1 ~ n), asks for virtual voltage mean value v _dc.

Step (2): rectification stage every step voltage nominal reference component the virtual voltage mean value v of step (1) gained is deducted through subtracter _dc, obtain voltage error component Δ v _dc.

Step (3): voltage error component Δ v _dccurrent on line side direct current real component reference value is drawn after PI controller

Step (4): sampling line voltage obtains three-phase voltage value v _sa, v _sb, v _sc, sampling power network current obtains three-phase electricity flow valuve i _sa, i _sb, i _sc.

Step (5): by step (4) sampling gained line voltage v _sa, v _sb, v _sclock phase angle theta is obtained after genlock module.

Step (6): the current i that step (4) obtains _sa, i _sb, i _scthe lock phase angle theta obtained with step (5) tries to achieve power network current real component actual value i after abc/dq conversion _sdwith idle component actual value i _sq.

Step (7): the current on line side direct current real component reference value that step (3) obtains the power network current real component actual value i that step (6) obtains is deducted through subtracter _sdobtain current on line side direct current real component margin of error Δ i _sd.

Step (8): current on line side direct current real component margin of error Δ i _sdby obtaining line voltage real component reference value after PI controller

Step (9): given power network current idle component reference value deduct the power network current idle component actual value i that step (6) obtains _sqobtain current on line side direct current reactive power error amount Δ i _sq.

Step (10): current on line side direct current reactive power error amount Δ i _sqby obtaining line voltage idle component reference value after PI controller

Step (11): the line voltage real component reference value that step (8) obtains with the line voltage idle component reference value obtained with step (10) three-phase modulations voltage is obtained after dq/abc conversion

Step (12): detect the every power P of rectification stage _a, P _b, P _c.

Step (13): according to formula try to achieve average power P _av.

Step (14): the every power P obtained by step (12) _a, P _b, P _crespectively divided by step (13) averaging of income power P _av, try to achieve every Power Correction Factor r _a, r _b, r _c.

Step (15): the three-phase modulations voltage that step (11) is tried to achieve with every Power Correction Factor r that step (14) is tried to achieve _a, r _b, r _cbring formula into $v_o=\frac{\max \{r_a\·v_{\mathrm{ca}}^{*},r_b\·v_{\mathrm{cb}}^{*},r_c\·v_{\mathrm{cc}}^{*}\}}{2}+\frac{\min \{r_a\·v_{\mathrm{ca}}^{*},r_b\·v_{\mathrm{cb}}^{*},r_c\·v_{\mathrm{cc}}^{*}\}}{2}$ In try to achieve voltage correction operand V ₀.

Step (16): the three-phase modulations voltage that step (11) is obtained deduct the voltage correction operand V that step (15) obtains respectively ₀try to achieve the modulation signal of every phase

Step (17): as figure(5) shown in, by rectification stage rated voltage deduct each H bridge submodule virtual voltage respectively the margin of error obtained obtains DC voltage static difference compensation rate v after PI controller _ki.

Step (18): deduct the DC voltage static difference compensation rate v that step (17) obtains respectively with unit feed-forward voltage coefficient 1 _ki, try to achieve every every grade H bridge submodule voltage and correct factor r _ki.

Step (19): by the modulation signal of every phase that step (16) obtains every the every grade H bridge submodule voltage being multiplied by step (18) gained respectively corrects factor r _kitry to achieve the drive singal of each switching tube

Through above-mentioned 19 steps, rectifier bridge is at the drive singal of gained the lower work of effect, balance modules output voltage, completes described transformer rectification stage voltage output function.

(2) energy storage stage is separated

Dispersion energy storage stage controls the discharge and recharge of energy-storage battery.According to the main network operation situation that checkout gear detects, energy-storage battery is divided into and fills a little and discharge process.Under main electrical network nominal situation, energy-storage battery is charged, until quantity of electric charge percentage SoC reaches rated value, enter poised state; Under poised state, control the balance of the energy-storage battery quantity of electric charge in a charging-discharging cycle; When main electrical network is under short time voltage is interrupted or the degree of depth is fallen, control energy-storage battery electric discharge, maintain the energy needed for the output of electric power electric transformer active power.Due in energy-storage battery dispersion separately access electric power electric transformer, each energy-storage battery charge and discharge process is passable independentcontrol.Whole charging controls to be realized by a quantity of electric charge outer shroud and a power inner ring; Whole control of discharge is realized by a power outer shroud and a quantity of electric charge inner ring;

figure(6) shown in, energy-storage battery discharge and recharge example is by a diverter switch, two adders, two subtracters, two proportional controllers, two integrator compositions.Concrete control procedure is as follows:

Step (1): detection of grid working condition, network operation situation is divided into nominal situation and damage.Abnormal condition refers to that electric line voltage short interruptions or the voltage degree of depth are fallen.

Step (2): as working properly in step (1) detection of grid, then diverter switch is switched to charge mode.Electrical network charges a battery, and is charged to required rated value.

Step (3): as the interruption of step (1) detection of grid short time voltage or the voltage degree of depth are fallen, then diverter switch is switched to charge mode.Energy storage battery discharges, and maintains described transformer rated output power.

The described charging of step (2) controls, and detailed process is:

1.: energy-storage battery charging charge reference value energy-storage battery electric charge actual charge value SoC is deducted through subtracter _kidraw energy-storage battery charge error component Δ SoC _ki.

2.: energy-storage battery charge error component Δ SoC _kithe power back-off margin of error is drawn through proportional controller

3.: the power back-off margin of error with charge power superposition just obtains energy-storage battery actual charge value SoC after integrator _ki.

By above-mentioned quantity of electric charge outer shroud and a power inner ring double-closed-loop control, energy-storage battery is charged to required rated value.

Step (3) described control of discharge, detailed process is:

1.: calculate electric power electric transformer power demand, obtain power command value

2.: electric power electric transformer actual power value is deducted through subtracter draw the discharge power margin of error

3.: the discharge power margin of error passing ratio controller draws energy-storage battery charge compensation margin of error Δ SoC _ki

4.: Δ SoC _kiwith energy-storage battery electric charge SoC _kielectric power electric transformer actual power value is obtained through integrator after superposition

By above-mentioned power outer shroud and quantity of electric charge inner ring double-closed-loop control, battery discharging.Electric power electric transformer obtains required rated output power.

Above-mentioned SoC is electric charge percentage, and it characterizes the state of charge of energy-storage battery, for the nominal charge amount of energy-storage battery.

(3) isolation level

DHB sampling obtains figureoutput current shown in 7 with output-current rating instruction compare and draw current error signal.Current error signal sends into current controller, and current controller can dynamic conditioning current error signal, until stable state time error signal is 0.The duty ratio D that current controller exports ^kijust DHB on high-tension side switching tube drive singal S is obtained after modulation _p, the drive singal S of low pressure side pipe _sobtained by phase shift.Controller chassis figureas figureshown in 7.By changing phase shifting angle φ ^kiadjustable output voltage, the switching tube phase shift of transformer both sides is illustrated figureas figureshown in 8.

figure(7) the control circuit example shown in is by a subtracter, and a current controller, a modulator forms.Concrete implementation step is:

Step (1) .DHB output current with output-current rating instruction current error signal Δ I is obtained through subtracter ₀

Step (2). current error signal obtains duty cycle signals D through current controller ^ki

Step (3). duty cycle signals D ^kidHB on high-tension side switching tube drive singal S is drawn through modulation _p

Step (4) .DHB on high-tension side switching tube drive singal S _pthrough phase shift θ ^kidraw the drive singal S of low pressure side pipe _s

Step (5). the switching signal S drawn _pand S _sdrive the switching tube work of DHB

(4): output stage

The concrete control method of output stage double-closed-loop control is: obtain dq DC component by abc/dq conversion, control, can realize floating in dq coordinate with PI to DC component.But introduce coupling amount (such as electric current in dq coordinate except being subject to voltage control quantity u _d, u _qoutside impact, also by the coupled voltages of inductance and output voltage impact) need decoupling zero to eliminate their impact.Decoupling zero after-current inner ring, outer voltage governing equation such as formula shown in (3), controller chassis figureas figure(9) shown in.

$\left\{\begin{array}{c}{u}_d=(K_{\mathrm{ip}}+\frac{K_{\mathrm{ii}}}{s})(i_m^{d^{*}}-i_m^d)-{\mathrm{\ω}}_b{L}_m{i}_m^q+u_f^d\\ u_q=(K_{\mathrm{ip}}+\frac{K_{\mathrm{ii}}}{s})(i_m^{q^{*}}-i_m^q)-{\mathrm{\ω}}_b{L}_m{i}_m^q+u_f^q\end{array}\right.\left\{\begin{array}{c}{i}_m^d=(K_{\mathrm{vp}}+\frac{K_{\mathrm{vi}}}{s})(u_f^{d^{*}}-u_f^d)-{\mathrm{\ω}}_b{C}_f{u}_f^q+i_g^d\\ i_m^q=(K_{\mathrm{vp}}+\frac{K_{\mathrm{vi}}}{s})(u_f^{q^{*}}-u_f^q)-{\mathrm{\ω}}_b{C}_f{u}_f^d+i_g^q\end{array}\right.---\left(3\right)$

figure(9) the control example shown in is by 6 subtracters, and 2 addition and subtraction blenders, 4 multipliers, 4 PI controllers form.Concrete implementation step is:

Step (1): output voltage DC component reference instruction value with output voltage DC component actual value voltage error signal is drawn through subtracter

Step (2): voltage error signal current signal is drawn through PI controller

Step (3): output voltage actual value be multiplied by ω _bc _fdraw couple current

Step (4): by load current DC component deduct the current signal of step (2) gained with the couple current of step (3) gained draw electric current loop reference instruction value

Step (5): by step (4) gained electric current loop reference instruction value with output current DC component actual value current error signal is drawn through subtracter

Step (6): current error signal voltage signal is drawn through PI controller

Step (7): output current actual value be multiplied by ω _bl _mdraw coupled voltages

Step (8): by output voltage DC component actual value deduct the voltage signal of step (6) gained with the coupled voltages of step (7) gained draw modulation voltage u _d

Step (9): output voltage DC component reference instruction value with output voltage DC component actual value voltage error signal is drawn through subtracter

Step (10): voltage error signal current signal is drawn through PI controller

Step (11): output voltage actual value be multiplied by ω _bc _fdraw couple current

Step (12): by load current DC component deduct the current signal of step (10) gained with the coupled voltages of step (11) gained draw electric current loop reference instruction value

Step (13): by step (12) gained electric current loop reference instruction value with output current DC component actual value current error signal is drawn through subtracter

Step (14): current error signal voltage signal is drawn through PI controller

Step (15): output current actual value be multiplied by ω _bl _mdraw coupled voltages

Step (16): by output voltage DC component actual value deduct the voltage signal of step (14) gained with the coupled voltages of step (15) gained draw modulation voltage u _q

Step (17): by step (8) gained modulation voltage u _dwith step (16) gained modulation voltage u _qafter dq/abc inverse transformation, produce drive singal, drive the work of inverter switching device pipe

Described L _mfor inverter filtering inductance, C _ffor inverter filtering electric capacity, ω _bfor inverter output voltage angular frequency.

Claims (9)

1. disperse an electric power electric transformer for energy storage, it is characterized in that: described electric power electric transformer comprises power cell and output module, described power cell comprises H bridge module, energy-storage module, isolation module; Each phase of the input of described electric power electric transformer all accesses the input of H bridge module, and the output of H bridge module is connected with the input of corresponding energy-storage module, and the output of energy-storage module is connected with the input of corresponding isolation module; Described H bridge module, the energy-storage module corresponding to H bridge module and the isolation module corresponding with energy-storage module form power cell; On each of electric power electric transformer is single-phase, access n power cell and an output module, the input of H bridge module is as the input of power cell, and the input of power cell is connected with electrical network, and mutually, cascade connects, alternate Y-connection; The output of isolation module is the output of power cell, and the output of power cell is in parallel, is connected with the input of output module;

All H bridge modules on each is single-phase form this single-phase on cascade rectifier level, all energy-storage modules on each is single-phase form this single-phase on dispersion energy storage stage, all isolation modules on each is single-phase form this single-phase on isolation level, output stage is made up of an output module.

Described energy-storage module comprises an One Buck-Boost converter body, and filter inductance and storage battery, storage battery is connected with One Buck-Boost converter body by filter inductance.

2. electric power electric transformer as claimed in claim 1, it is characterized in that: described dispersion energy storage stage controls the discharge and recharge of energy-storage battery, under main electrical network nominal situation, charges to energy-storage battery, until quantity of electric charge percentage SoC reaches rated value, enter poised state; Under poised state, control the balance of the energy-storage battery quantity of electric charge in a charging-discharging cycle; Main electrical network, when short time voltage is interrupted or the degree of depth falls, controls energy-storage battery electric discharge.

3. the control method of electric power electric transformer as claimed in claim 1, is characterized in that: the rate-determining steps of cascade rectifier level comprises as follows:

Step S1: the virtual voltage of sampling cascade rectification stage every grade of H bridge module k represents phase (k ∈ a, b, c), and i represents progression (i ∈ 1 ~ n), asks for virtual voltage mean value v _dc;

Step S2: rectification stage every step voltage nominal reference component the virtual voltage mean value v of step (1) gained is deducted through subtracter _dc, obtain voltage error component Δ v _dc;

Step S3: voltage error component Δ v _dccurrent on line side direct current real component reference value is drawn after PI controller

Step S4: calculate power network current real component actual value i _sdwith idle component actual value i _sq;

Step S5: the step S3 current on line side direct current real component reference value obtained the power network current real component actual value i of step S4 gained is deducted through subtracter _sdobtain current on line side direct current real component margin of error Δ i _sd;

Step S6: current on line side direct current real component margin of error Δ i _sdby obtaining line voltage real component reference value after PI controller

Step S7: given power network current idle component reference value deduct the power network current idle component actual value i that step S4 obtains _sqobtain current on line side direct current reactive power error amount Δ i _sq;

Step S8: current on line side direct current reactive power error amount Δ i _sqby obtaining line voltage idle component reference value after PI controller

Step S9: the line voltage real component reference value that step (8) obtains with the line voltage idle component reference value obtained with step (10) three-phase modulations voltage is obtained after dq/abc conversion

Step S10: calculating voltage correction operand V ₀;

Step S11: the three-phase modulations voltage that step (11) is obtained deduct the voltage correction operand V that step (15) obtains respectively ₀try to achieve the modulation signal of every phase

Step S12: calculate every every grade H bridge submodule voltage and correct factor r _ki;

Step S13: by the modulation signal of every phase that step S11 obtains be multiplied by H bridge submodule voltage respectively and correct factor r _kitry to achieve the drive singal of each IGBT pipe

4. control method as claimed in claim 3, it is characterized in that, described step S4 comprises:

Step S41: sampling line voltage obtains three-phase voltage value v _sa, v _sb, v _sc, sampling power network current obtains three-phase electricity flow valuve i _sa, i _sb, i _sc;

Step S42: by step (4) sampling gained line voltage v _sa, v _sb, v _sclock phase angle theta is obtained after genlock module;

Step S43: the current i that step (4) obtains _sa, i _sb, i _scthe lock phase angle theta obtained with step (5) tries to achieve power network current real component actual value i after abc/dq conversion _sdwith idle component actual value i _sq.

5. control method as claimed in claim 3, it is characterized in that, described step S10 comprises:

Step S101: detect the every power P of rectification stage _a, P _b, P _c;

Step S102: according to formula try to achieve average power P _av;

Step S103: the every power P obtained by step (12) _a, P _b, P _crespectively divided by step (13) averaging of income power P _av, try to achieve every Power Correction Factor r _a, r _b, r _c;

Step S104: the three-phase modulations voltage that step (11) is tried to achieve with every Power Correction Factor r that step (14) is tried to achieve _a, r _b, r _cbring formula into

in try to achieve voltage correction operand V ₀.

6. control method as claimed in claim 3, it is characterized in that, described step S12 comprises:

Step S121: by rectification stage voltagerating reference component deduct each H bridge submodule virtual voltage respectively the margin of error obtained obtains DC voltage static difference compensation rate v after PI controller _ki;

Step S122: deduct the DC voltage static difference compensation rate v that step (17) obtains respectively with unit feed-forward voltage coefficient 1 _ki, try to achieve every every grade H bridge submodule voltage and correct factor r _ki.

7. the control method of electric power electric transformer as claimed in claim 1, is characterized in that: the process of the discharge and recharge of energy-storage battery comprises the steps:

Step (1): detection of grid working condition, network operation situation is divided into nominal situation and damage.Abnormal condition refers to that electric line voltage short interruptions or the voltage degree of depth are fallen;

Step (2): as working properly in step (1) detection of grid, then diverter switch is switched to charge mode.Electrical network charges a battery, and is charged to required rated value;

Step (3): as the interruption of step (1) detection of grid short time voltage or the voltage degree of depth are fallen, then diverter switch is switched to charge mode, and energy storage battery discharges, and maintains described transformer rated output power;

Step (2) described charging control process, comprises the following steps:

1.: energy-storage battery charging charge reference value energy-storage battery electric charge actual charge value SoC is deducted through subtracter _kidraw energy-storage battery charge error component Δ SoC _ki;

2.: energy-storage battery charge error component Δ SoC _kithe power back-off margin of error is drawn through proportional controller

3.: the power back-off margin of error with charge power superposition just obtains energy-storage battery actual charge value SoC after integrator _ki;

By above-mentioned quantity of electric charge outer shroud and a power inner ring double-closed-loop control, energy-storage battery is charged to required rated value;

The described control of discharge process of step (3), comprises the following steps:

1. calculate electric power electric transformer power demand, obtain power command value

2. electric power electric transformer actual power value is deducted through subtracter draw the discharge power margin of error

3. the discharge power margin of error passing ratio controller draws energy-storage battery charge compensation margin of error Δ SoC _ki;

4. Δ SoC _kiwith energy-storage battery electric charge SoC _kielectric power electric transformer actual power value is obtained through integrator after superposition

By above-mentioned power outer shroud and quantity of electric charge inner ring double-closed-loop control, battery discharging, electric power electric transformer obtains required rated output power;

Above-mentioned SoC is electric charge percentage, and it characterizes the state of charge of energy-storage battery, for the nominal charge amount of energy-storage battery.

8. the control method of electric power electric transformer as claimed in claim 1, is characterized in that: isolation class control process comprises the steps:

Step (1). isolation level output current with output-current rating instruction current error signal Δ I is obtained through subtracter ₀;

Step (2). current error signal obtains duty cycle signals D through current controller ^ki;

Step (3). duty cycle signals D ^kiisolation level on high-tension side switching tube drive singal S is drawn through modulation _p;

Step (4). isolation level on high-tension side switching tube drive singal S _pthrough phase shift θ ^kidraw the drive singal S of low pressure side pipe _s;

Step (5). the switching signal S that step (3) and step (4) obtain _pand S _sthe switching tube work of driving isolation level.

9. the control method of electric power electric transformer as claimed in claim 1, is characterized in that: export class control process and comprise the steps:

Step (1): output voltage DC component reference instruction value with output voltage DC component actual value voltage error signal is drawn through subtracter

Step (2): voltage error signal current signal is drawn through PI controller

Step (3): output voltage actual value be multiplied by ω _bc _fdraw couple current

Step (4): by load current DC component deduct the current signal of step (2) gained with the couple current of step (3) gained draw electric current loop reference instruction value

Step (5): by step (4) gained electric current loop reference instruction value with output current DC component actual value current error signal is drawn through subtracter

Step (6): current error signal voltage signal is drawn through PI controller

Step (7): output current actual value be multiplied by ω _bl _mdraw coupled voltages

Step (8): by output voltage DC component actual value deduct the voltage signal of step (6) gained with the coupled voltages of step (7) gained draw modulation voltage u _d;

Step (9): output voltage DC component reference instruction value with output voltage DC component actual value voltage error signal is drawn through subtracter

Step (10): voltage error signal current signal is drawn through PI controller

Step (11): output voltage actual value be multiplied by ω _bc _fdraw couple current

Step (12): by load current DC component deduct the current signal of step (10) gained with the coupled voltages of step (11) gained draw electric current loop reference instruction value

Step (13): by step (12) gained electric current loop reference instruction value with output current DC component actual value current error signal is drawn through subtracter

Step (14): current error signal voltage signal is drawn through PI controller

Step (15): output current actual value be multiplied by ω _bl _mdraw coupled voltages

Step (16): by output voltage DC component actual value deduct the voltage signal of step (14) gained with the coupled voltages of step (15) gained draw modulation voltage u _q;

Step (17): by step (8) gained modulation voltage u _dwith step (16) gained modulation voltage u _qafter dq/abc inverse transformation, produce drive singal, drive the work of inverter switching device pipe;

Described L _mfor inverter filtering inductance, C _ffor inverter filtering electric capacity, ω _bfor inverter output voltage angular frequency.