CN113659862A - Photovoltaic and energy storage integrated power converter topology and control method thereof - Google Patents

Photovoltaic and energy storage integrated power converter topology and control method thereof Download PDF

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CN113659862A
CN113659862A CN202110989818.0A CN202110989818A CN113659862A CN 113659862 A CN113659862 A CN 113659862A CN 202110989818 A CN202110989818 A CN 202110989818A CN 113659862 A CN113659862 A CN 113659862A
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bridge unit
bridge
output
power
voltage
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雷家兴
全相军
李淑锋
王方胜
李吉平
郑涛
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Southeast University
State Grid Eastern Inner Mongolia Power Co Ltd
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State Grid Eastern Inner Mongolia Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53873—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/60—Planning or developing urban green infrastructure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

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  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention discloses a photovoltaic and energy storage integrated power converter topology and a control method thereof, wherein the power converter topology comprises a half-bridge unit, a filter element and a direct current power supply, the half-bridge unit comprises a first half-bridge unit H1, a second half-bridge unit H2 and a third half-bridge unit H3, and the direct current power supply comprises a first direct current power supply u1And a second DC power supply u2The filter element comprises a first filter inductor Lh1A second filter inductor Lh2A third filter inductor Lh3And a fourth filter inductor LoA first filter capacitor C1And a second filter capacitor C2. The power converter topology can realize integrated operation of photovoltaic and energy storage only by 6 full-control power devices, so that the operation cost of the system is obviously reduced; power converter topology junction of the inventionThe structure has the characteristics of strong technical competitiveness and high practical value, and is favorable for promoting the application and development of photovoltaic and energy storage integrated power conversion equipment.

Description

Photovoltaic and energy storage integrated power converter topology and control method thereof
Technical Field
The invention relates to the field of power converters, in particular to a photovoltaic and energy storage integrated power converter topology and a control method thereof.
Background
A photovoltaic and energy storage integrated power converter is a device which is applied to a photovoltaic and energy storage combined power generation system to realize direct current/alternating current electric energy conversion. The device can coordinate and control the output of the photovoltaic and the energy storage battery, stabilize the power fluctuation of the photovoltaic battery, and output alternating current electric energy meeting the standard requirement through a high-frequency power electronic technology to supply power to a load. The device can realize the functions of maximum power tracking of the photovoltaic cell panel, energy fine management of the energy storage battery, automatic switching of the grid-connected mode/off-grid mode and the like, has excellent control performance, attracts wide attention of academic circles and industrial circles, and has a wide market application prospect.
Fig. 1 is a typical photovoltaic and energy storage integrated power converter topology. In the figure, u1And u2The two dc power sources may represent a photovoltaic panel or an energy storage battery, respectively. Two direct current power supplies are connected to a public direct current bus through a half-bridge unit respectively, a single-phase full-bridge inverter converts direct current bus voltage into output side alternating current voltage, and the output can be connected with an alternating current power grid or a passive load. The scheme can realize independent control of each direct current port and each alternating current port, so that the control method has the advantages of simplicity in control and easiness in realization. However, this topology also has significant problems as follows: (1) the number of required power devices is as many as 8 full-control power devices; (2) high-frequency common mode voltage exists between each direct current power supply and the alternating current output, and large leakage current exists when an isolation transformer is not added; (3) between any two DC power sources, between DC power source and AC outputAnd the interval is two-stage power conversion, so that the loss is large and the efficiency is low.
Disclosure of Invention
The invention aims to provide a photovoltaic and energy storage integrated power converter topology and a control method thereof, which solve the problems of the existing topology, lower the cost, improve the operation performance of the power converter in all directions and promote the further development of the photovoltaic and energy storage integrated application.
The purpose of the invention can be realized by the following technical scheme:
a photovoltaic and energy storage integrated power converter topology comprises half-bridge units, a filtering element and a direct current power supply, wherein each half-bridge unit comprises a first half-bridge unit H1, a second half-bridge unit H2 and a third half-bridge unit H3, and the direct current power supply comprises a first direct current power supply u1And a second DC power supply u2The filter element comprises a first filter inductor Lh1A second filter inductor Lh2A third filter inductor Lh3And a fourth filter inductor LoA first filter capacitor C1And a second filter capacitor C2；
The first DC power supply u1Is connected to the positive pole through a first filter inductor Lh1The bridge arm middle point is connected to the first half bridge unit H1; a first filter capacitor C is arranged on a direct current bus of the first half-bridge unit H11The positive pole passes through a fourth filter inductor LoIs connected to the output voltage u0The positive electrode of (1);
the second DC power supply u2Is connected to the positive pole through a second filter inductor Lh2The bridge arm midpoint connected to the second half-bridge unit H2; a second filter capacitor C is arranged on a direct current bus of the second half-bridge unit H22The positive pole is connected to the output voltage u0The negative electrode of (1); second DC power supply u2Is connected to the positive pole through a third filter inductor Lh3The bridge arm midpoint connected to the third half-bridge unit H3; the positive electrode of the DC bus of the third half-bridge unit H3 and the first DC power supply u1Connecting the positive electrodes; the cathodes of the two direct current power supplies and the cathodes of the direct current buses of the three half-bridge units are grounded.
Further, the firstDC power supply u1And a second DC power supply u2Is a photovoltaic cell or an energy storage cell.
Further, when the power converter topology is in a steady state, the voltage drop across the filter inductor and the current across the filter capacitor approach zero, and then:
udc1-udc2＝uo
wherein u isdc1Is the dc bus voltage of half-bridge cell H1; u. ofdc2Is the DC bus voltage of half-bridge cell H2oIs an ac output voltage.
Further, consider said udc1、udc2And uoHas a direct current component and an alternating current component of
Figure BDA0003232085760000031
Udc1And Udc2The dc components of the dc bus voltages of the first half-bridge unit H1 and the second half-bridge unit H2 are respectively shown, and the dc bus voltages of the first half-bridge unit H1 and the second half-bridge unit H2 should be equal in a steady state;
from the above formula it can be deduced:
Figure BDA0003232085760000032
Udc＝Udc1＝Udc2the parameter a is any real number, and the fourth filter inductor LoOutput current ioSimultaneously flows through the DC buses of the first half-bridge unit H1 and the second half-bridge unit H2 and the output voltage uo。
Further, the parameter a is a ratio of active power provided by the first half-bridge unit H1 to the output, and a parameter a being 0 indicates that the first half-bridge unit H1 does not provide active power to the output and the second half-bridge unit H2 provides full active power; the parameter a is 0.5, which indicates that the first half-bridge unit H1 and the second half-bridge unit H2 provide the same active power to the output; the parameter a-1 indicates that the first half-bridge unit H1 provides full active power and the second half-bridge unit H2 does not provide active power to the output; the parameter a-1 indicates that the first half bridge unit H1 absorbs the same power as the load.
Further, the power converter topology is in a steady state and the AC output voltage uoAnd an output current ioAre all sinusoidal, uoAnd ioExpressed as:
Figure BDA0003232085760000033
Uomto output the voltage amplitude, iomFor outputting the current amplitude, omegaoIn order to output the angular frequency of the output,
Figure BDA0003232085760000034
is the output power factor angle.
Further, the first half-bridge unit H1 and the second half-bridge unit H2 provide p instantaneous apparent power to the outputdc1And pdc2Expressed as:
Figure BDA0003232085760000041
bridge leg currents i of the first half-bridge cell H1 and the second half-bridge cell H2h1And ih2Expressed as:
Figure BDA0003232085760000042
ih1and ih2In steady state, the frequency of the DC component is the output frequency omegaoAnd an alternating current component having a frequency twice the output frequency.
A control method of a photovoltaic and energy storage integrated power converter topology, the control method comprising the steps of:
s1 collecting output voltage uoAnd a fourth filter inductor LoCurrent i ofoAnd using a voltage ofThe current closed loop control generates a DC bus voltage difference signal reference value u of the first half-bridge unit H1 and the second half-bridge unit H2x *；
S2, setting the DC bus voltage reference value of the first half-bridge unit H1 and the second half-bridge unit H2 to udc1 *And udc2 *The expression is:
Figure BDA0003232085760000043
in the formula of Udc *Setting a direct current component of a direct current bus voltage reference value; a is a power distribution coefficient, and the value range of the power distribution coefficient is any real number;
s3, collecting bridge arm current i of the first half bridge unit H1h1And the DC bus voltage udc1And performing voltage and current closed-loop control so that udc1At steady state with udc1 *The same;
s4, collecting bridge arm current i of the second half-bridge unit H2h2And the DC bus voltage udc2And performing voltage and current closed-loop control so that udc2At steady state with udc2 *The same;
s5 setting the bridge arm current i of the third half bridge unit H3h3Has a reference value of ih3 *Collecting the current ih3And closed-loop control is performed so that ih3At steady state with ih3 *The same is true.
Further, U in S2dc *Need to satisfy at any moment:
Figure BDA0003232085760000051
and
Figure BDA0003232085760000052
wherein, U1And U2Are respectively a first DC power supply u1And a second DC power supply u2The voltage of (c).
Further, i in said S5h3 *The setting method comprises the following steps:
Figure BDA0003232085760000053
in the formula Ih3 *Represents ih3 *A direct current component of;
Figure BDA0003232085760000054
the representative frequency is an alternating current component of the output frequency, and c is a weight coefficient;
Figure BDA0003232085760000055
representing an alternating current component with a frequency twice the output frequency, d being a weight coefficient; function(s)
Figure BDA0003232085760000056
Representation extraction
Figure BDA0003232085760000057
The medium frequency is an alternating component of twice the output frequency.
The invention has the beneficial effects that:
1. the power converter topology can realize integrated operation of photovoltaic and energy storage only by 6 full-control power devices, so that the operation cost of the system is obviously reduced;
2. in the power converter topology, high-frequency common mode voltage does not exist between each direct current power supply and alternating current output, the problem of leakage current can be solved without an isolation transformer, and the operation safety and reliability of equipment are improved;
3. according to the power converter topology, single-stage power conversion is performed between two direct current power supplies, between the direct current power supply and the alternating current output, so that the system loss is reduced, and the operation efficiency of equipment is improved;
4. the power converter topological structure has the characteristics of strong technical competitiveness and high practical value, and is favorable for promoting the application and development of photovoltaic and energy storage integrated power conversion equipment.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a conventional photovoltaic and energy storage integrated power converter topology;
fig. 2 is a power converter topology diagram of the invention integrating photovoltaic and energy storage.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A photovoltaic and energy storage integrated power converter topology comprises half-bridge units, a filter element and a direct current power supply, wherein the half-bridge units comprise a first half-bridge unit H1, a second half-bridge unit H2 and a third half-bridge unit H3, and the direct current power supply comprises a first direct current power supply u1And a second DC power supply u2The filter element comprises a first filter inductor Lh1A second filter inductor Lh2A third filter inductor Lh3And a fourth filter inductor LoA first filter capacitor C1And a second filter capacitor C2。
A first DC power supply u1And a second DC power supply u2Can be photovoltaic cell or energy storage cell, and the first direct current power supply u1Is connected to the positive pole through a first filter inductor Lh1The bridge arm middle point is connected to the first half bridge unit H1; a first filter capacitor C is arranged on a direct current bus of the first half-bridge unit H11The positive pole passes through a fourth filter inductor LoIs connected to the output voltage u0The positive electrode of (1); second DC power supply u2Is connected to the positive pole through a second filter inductor Lh2The bridge arm midpoint connected to the second half-bridge unit H2; DC bus of second half-bridge unit H2Upper mounting second filter capacitor C2The positive pole is connected to the output voltage u0The negative electrode of (1); second DC power supply u2Is connected to the positive pole through a third filter inductor Lh3The bridge arm midpoint connected to the third half-bridge unit H3; the positive electrode of the DC bus of the third half-bridge unit H3 and the first DC power supply u1Connecting the positive electrodes; the cathodes of the two direct current power supplies and the cathodes of the direct current buses of the three half-bridge units are grounded.
Due to the second filter capacitor C2Is close to 0, so that the ac output voltage u0The negative pole of the transformer has no high-frequency common mode voltage to the ground, and the topology of the power converter can not generate high-frequency leakage current, so that the safety and the reliability of the operation of equipment can be improved.
The first DC power u is used1Representing an energy storage battery, a second DC power supply u2The working principle of the power converter topology is explained on behalf of a photovoltaic panel. In a steady state, the voltage drop of the filter inductor and the current of the filter capacitor are negligible. Then can be known from the figure
udc1-udc2＝uo (1)
Wherein u isdc1Is the dc bus voltage of the first half bridge cell H1; u. ofdc2Is the DC bus voltage, u, of the second half-bridge cell H2oIs an ac output voltage. Further considering the dc component and the ac component of each term in equation (1), there are:
Figure BDA0003232085760000071
wherein, Udc1And Udc2Represents the DC component, u, in the DC bus voltage of the first H1 and second H2 half bridge cells, respectivelyx1And ux2The alternating current components are represented, respectively. Equation (2) shows that the dc bus voltage dc components of the first half-bridge unit H1 and the second half-bridge unit H2 should be equal in steady state, and the difference between the ac components should be equal to the output voltage u0. Then, the following equations (1) and (2) can be obtained:
Figure BDA0003232085760000072
wherein, Udc＝Udc1＝Udc2And a is any real number. As can be seen from equation (3) and FIG. 2, since the output current ioFlows through the DC bus of the first half-bridge unit H1 and the second half-bridge unit H2 simultaneously and outputs a voltage uoThe parameter a represents the ratio of the active power provided by the first half bridge unit H1 to the output. If a is 0, the first half-bridge unit H1 provides no active power to the output, and the second half-bridge unit H2 provides full active power; a-0.5 means that the first half-bridge unit H1 and the second half-bridge unit H2 provide the same active power to the output; a equals 1 indicating that the first half-bridge unit H1 provides full active power and the second half-bridge unit H2 does not provide active power to the output; a-1 indicates that the first half-bridge unit H1 absorbs the same power as the load, and the second half-bridge unit H2 not only provides the full output power, but also indirectly supplies the first dc power u via the output1And transmitting power, which is suitable for the application scene of charging the energy storage battery.
AC output voltage u in the case of steady stateoAnd an output current ioAll are sine, u is not generaloAnd ioCan be expressed as:
Figure BDA0003232085760000081
wherein, UomTo output the voltage amplitude, iomFor outputting the current amplitude, omegaoIn order to output the angular frequency of the output,
Figure BDA0003232085760000082
is the output power factor angle. Then, as can be seen from fig. 2, the instantaneous apparent power provided to the output by the first half-bridge unit H1 and the second half-bridge unit H2 is pdc1And pdc2：
Figure BDA0003232085760000083
It can be seen that the instantaneous apparent power provided by the first half-bridge unit H1 and the second half-bridge unit H2 contains a DC component and has a frequency of the output frequency ωoAnd an alternating current component having a frequency twice the output frequency. Further, as can be seen from the principle of power balance, the bridge arm currents i of the first half-bridge unit H1 and the second half-bridge unit H2h1And ih2Can be expressed as:
Figure BDA0003232085760000084
formula (6) shows thath1And ih2In a steady state, the frequency of the DC component is an output frequency omegaoAnd an alternating current component having a frequency twice the output frequency.
According to the above analysis, a closed-loop control method for the first half-bridge unit H1 and the second half-bridge unit H2 can be obtained, which comprises the following steps:
s1: collecting output voltage uoAnd a fourth filter inductor LoCurrent i ofoAnd a voltage and current closed-loop control is adopted to generate a direct current bus voltage difference value signal reference value u of the first half-bridge unit H1 and the second half-bridge unit H2x *Wherein u isx *I.e. u in the formula (3)x1-ux2To the reference value of (c). For a single-phase inverter, the closed-loop control designed in this step may adopt a typical voltage-current double closed-loop control strategy based on a resonance controller under a static coordinate system, wherein the resonance frequency of the resonance controller is set to be the output frequency ωo。
S2: setting the DC bus voltage reference value of the first half-bridge unit H1 and the second half-bridge unit H2 to udc1 *And udc2 *The expression is:
Figure BDA0003232085760000091
in the formula of Udc *To setA direct current component of a direct current bus voltage reference value; and a is a power distribution coefficient, and the value range of the power distribution coefficient is any real number. And a can be dynamically adjusted according to the work output condition of the photovoltaic cell panel and the residual capacity of the energy storage battery. According to the working principle of the half-bridge circuit, the direct current bus voltage value of any half-bridge circuit is larger than the bridge arm voltage. Then, U is represented by the formula (7)dc *Need to satisfy at any moment:
Figure BDA0003232085760000092
and
Figure BDA0003232085760000093
in practice, it is possible to vary the voltage range of the photovoltaic cell, the voltage range of the energy storage cell and the output voltage u0The fixed U is set by the formulas (8) and (9)dc *And U can be adjusted in real time according to the real-time voltage of the photovoltaic cell and the voltage of the energy storage celldc *The size of (2).
S3: collecting bridge arm current i of first half bridge unit H1h1And the DC bus voltage udc1And performing voltage and current closed-loop control so that udc1At steady state with udc1 *The same is true. According to the working principle of the half-bridge circuit, the outer ring u can be adopteddc1Closed loop control with inner loop of ihA double closed-loop control strategy for closed-loop control. As can be seen from the expressions (3) and (6), u is the steady statedc1And ih1Both contain DC component and AC component, so that u can be controlled in closed loopdc1A proportional-integral-resonance controller is adopted, wherein the proportional controller is used for adjusting the dynamic response speed, the integral controller is used for realizing the non-static tracking of the direct current component, and the resonance controller is used for realizing the non-static tracking of the alternating current component. From the formula (3), udc1Containing only frequency ωoA single AC component of (i), then u can bedc1Has a resonant frequency of omegao. The inner loop also uses a proportional-integral-resonance controller pair ih1Closed loop regulation is performed. As shown in formula (6), ih1Comprising a frequency of ωoAnd 2 omegaoTwo alternating current components of (i)h1Need to adopt resonance frequencies of omega respectivelyoAnd 2 omegaoThe composite resonance controller of (1).
S4: collecting bridge arm current i of second half-bridge unit H2h2And the DC bus voltage udc2And performing voltage and current closed-loop control so that udc2At steady state with udc2 *The same is true. The specific closed-loop control method and controller structure is the same as that of the first half bridge unit H1.
The function and operating principle of the third half-bridge cell H3 is further explained below. As can be seen from fig. 2 and equation (6), when the third half-bridge unit H3 is not active, the current output by the energy storage battery is ih1The current output by the photovoltaic cell is ih2Both of which contain a DC component and have a frequency of an output frequency omegaoAnd an alternating current component having a frequency twice the output frequency. The energy storage battery can receive an alternating current component with a certain capacity, but the photovoltaic cell panel generally needs to work in a maximum power tracking mode, and the output current of the photovoltaic cell panel only has a direct current component. To this end, the invention provides for the third half-bridge unit H3 to eliminate the photovoltaic cell (second dc source u)2) In ac ripple, i.e. by controlling so that ih3A.c. component of (a) and (i)h2Are the same as above. Meanwhile, the third half-bridge unit H3 also provides a direct energy flow path from the photovoltaic cell to the energy storage cell, so that when the amount of electricity generated by the photovoltaic cell is greater than the load demand, the remaining electricity can be efficiently stored in the energy storage cell.
The method for controlling the third half-bridge unit H3 is further described below, and specifically includes the following steps:
s5: setting the leg current i of the third half-bridge cell H3h3Has a reference value of ih3 *Collecting the current ih3And closed-loop control is performed so that ih3At steady state with ih3 *The same is true. Wherein ih3 *The setting method comprises the following steps:
Figure BDA0003232085760000101
in the formula Ih3 *Represents ih3 *The direct current component is used for controlling the power of the photovoltaic cell flowing to the energy storage cell, and can be dynamically adjusted according to the work output condition of the photovoltaic cell panel and the residual capacity of the energy storage cell in practical application;
Figure BDA0003232085760000111
representing the ac component with the output frequency, c is a weight coefficient, and c equals 0, which means that the third half-bridge unit H3 does not eliminate the second dc power u2The frequency of the alternating current is the alternating current component of the output frequency, and c is 1, which means that the alternating current component is completely eliminated;
Figure BDA0003232085760000112
representing an alternating component with a frequency of twice the output frequency, d is a weight coefficient, and the meaning is similar to c; function(s)
Figure BDA0003232085760000113
Representation extraction
Figure BDA0003232085760000114
The medium frequency is an alternating current component with twice output frequency, and can be realized by adopting a band-pass filter or a generalized second-order integrator and the like in practice. According to the formula (10), ih3Also comprises a plurality of frequency components, and can adopt controllers such as proportional-integral-resonance and the like to realize closed-loop control, a specific control structure and ih2Are the same as above.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.

Claims (10)

1. A photovoltaic and energy storage integrated power converter topology is characterized by comprising a half-bridge unit, a filter element and a direct current power supply, wherein the half-bridge unit comprises a first half-bridge unit H1, a second half-bridge unit H2 and a third half-bridge unit H3, and the direct current power supply comprises a first direct current power supply u1And a second DC power supply u2The filter element comprises a first filter inductor Lh1A second filter inductor Lh2A third filter inductor Lh3And a fourth filter inductor LoA first filter capacitor C1And a second filter capacitor C2；
The first DC power supply u1Is connected to the positive pole through a first filter inductor Lh1The bridge arm middle point is connected to the first half bridge unit H1; a first filter capacitor C is arranged on a direct current bus of the first half-bridge unit H11The positive pole passes through a fourth filter inductor LoIs connected to the output voltage u0The positive electrode of (1);
the second DC power supply u2Is connected to the positive pole through a second filter inductor Lh2The bridge arm midpoint connected to the second half-bridge unit H2; a second filter capacitor C is arranged on a direct current bus of the second half-bridge unit H22The positive pole is connected to the output voltage u0The negative electrode of (1); second DC power supply u2Is connected to the positive pole through a third filter inductor Lh3The bridge arm midpoint connected to the third half-bridge unit H3; the positive electrode of the DC bus of the third half-bridge unit H3 and the first DC power supply u1Connecting the positive electrodes; negative poles of two DC power supplies and three half-bridge unitsThe negative poles of the current buses are all grounded.
2. The integrated photovoltaic and energy storage power converter topology of claim 1, wherein the first direct current power source u1And a second DC power supply u2Is a photovoltaic cell or an energy storage cell.
3. The integrated photovoltaic and energy storage power converter topology of claim 2, wherein when the power converter topology is in a steady state, a voltage drop across the filter inductor and a current across the filter capacitor approach zero, then:
udc1-udc2＝uo
wherein u isdc1Is the dc bus voltage of half-bridge cell H1; u. ofdc2Is the DC bus voltage of half-bridge cell H2oIs an ac output voltage.
4. A photovoltaic and energy storage integrated power converter topology according to claim 3, characterized in that said u is taken into accountdc1、udc2And uoHas a direct current component and an alternating current component of
Figure FDA0003232085750000021
Udc1And Udc2The dc components of the dc bus voltages of the first half-bridge unit H1 and the second half-bridge unit H2 are respectively shown, and the dc bus voltages of the first half-bridge unit H1 and the second half-bridge unit H2 should be equal in a steady state;
from the above formula it can be deduced:
Figure FDA0003232085750000022
Udc＝Udc1＝Udc2the parameter a is any real number, and the fourth filter inductor LoOutput current ioSimultaneously flows through the DC buses of the first half-bridge unit H1 and the second half-bridge unit H2 and the output voltage uo。
5. The integrated photovoltaic and energy storage power converter topology of claim 4, wherein the parameter a is a ratio of active power provided by the first half-bridge unit H1 to the output, and the parameter a-0 indicates that the first half-bridge unit H1 does not provide active power to the output and the second half-bridge unit H2 provides full active power; the parameter a is 0.5, which indicates that the first half-bridge unit H1 and the second half-bridge unit H2 provide the same active power to the output; the parameter a-1 indicates that the first half-bridge unit H1 provides full active power and the second half-bridge unit H2 does not provide active power to the output; the parameter a-1 indicates that the first half bridge unit H1 absorbs the same power as the load.
6. The integrated photovoltaic and energy storage power converter topology of claim 5, wherein the power converter topology is in a steady state and has an AC output voltage uoAnd an output current ioAre all sinusoidal, uoAnd ioExpressed as:
Figure FDA0003232085750000023
Uomto output the voltage amplitude, iomFor outputting the current amplitude, omegaoIn order to output the angular frequency of the output,
Figure FDA0003232085750000024
is the output power factor angle.
7. The integrated photovoltaic and energy storage power converter topology of claim 6, wherein the instantaneous apparent power provided by the first half-bridge unit H1 and the second half-bridge unit H2 to the output is pdc1And pdc2Expressed as:
Figure FDA0003232085750000031
bridge leg currents i of the first half-bridge cell H1 and the second half-bridge cell H2h1And ih2Expressed as:
Figure FDA0003232085750000032
ih1and ih2In steady state, the frequency of the DC component is the output frequency omegaoAnd an alternating current component having a frequency twice the output frequency.
8. The control method of the integrated photovoltaic and energy storage power converter topology according to claim 1, characterized in that the control method comprises the following steps:
s1 collecting output voltage uoAnd a fourth filter inductor LoCurrent i ofoAnd a voltage and current closed-loop control is adopted to generate a direct current bus voltage difference value signal reference value u of the first half-bridge unit H1 and the second half-bridge unit H2x *；
S2, setting the DC bus voltage reference value of the first half-bridge unit H1 and the second half-bridge unit H2 to udc1 *And udc2 *The expression is:
Figure FDA0003232085750000033
in the formula of Udc *Setting a direct current component of a direct current bus voltage reference value; a is a power distribution coefficient, and the value range of the power distribution coefficient is any real number;
s3, collecting bridge arm current i of the first half bridge unit H1h1And the DC bus voltage udc1And performing voltage and current closed-loop control so that udc1At steady state with udc1 *The same;
s4, collecting bridge arm current i of the second half-bridge unit H2h2And the DC bus voltage udc2And performing voltage and current closed-loop control so that udc2At steady state with udc2 *The same;
s5 setting the bridge arm current i of the third half bridge unit H3h3Has a reference value of ih3 *Collecting the current ih3And closed-loop control is performed so that ih3At steady state with ih3 *The same is true.
9. The control method according to claim 8, wherein U in S2dc *Need to satisfy at any moment:
Figure FDA0003232085750000041
and
Figure FDA0003232085750000042
wherein, U1And U2Are respectively a first DC power supply u1And a second DC power supply u2The voltage of (c).
10. The control method according to claim 9, wherein i in S5h3 *The setting method comprises the following steps:
Figure FDA0003232085750000043
in the formula Ih3 *Represents ih3 *A direct current component of;
Figure FDA0003232085750000044
the representative frequency is an alternating current component of the output frequency, and c is a weight coefficient;
Figure FDA0003232085750000045
representing an alternating current component with a frequency twice the output frequency, d being a weight coefficient; function(s)
Figure FDA0003232085750000046
Representation extraction
Figure FDA0003232085750000047
The medium frequency is an alternating component of twice the output frequency.
CN202110989818.0A 2021-08-26 2021-08-26 Photovoltaic and energy storage integrated power converter topology and control method thereof Withdrawn CN113659862A (en)

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CN210167979U (en) * 2019-07-31 2020-03-20 上海电力大学 Non-isolated single-phase photovoltaic grid-connected inverter for inhibiting common-mode current
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104917393A (en) * 2015-06-09 2015-09-16 合肥科威尔电源系统有限公司 Photovoltaic and energy-storage integrated DC converter structure based on MMC technology
WO2017031880A1 (en) * 2015-08-27 2017-03-02 无锡伊佩克科技有限公司 Method for controlling optically-coupled isolation vehicle-mounted power supply photovoltaic inverter
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