CN114172166A - Voltage generating device and high-frequency generation control method thereof - Google Patents

Voltage generating device and high-frequency generation control method thereof Download PDF

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Publication number
CN114172166A
CN114172166A CN202111485686.4A CN202111485686A CN114172166A CN 114172166 A CN114172166 A CN 114172166A CN 202111485686 A CN202111485686 A CN 202111485686A CN 114172166 A CN114172166 A CN 114172166A
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phase
voltage
frequency
output
frequency voltage
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陈凯
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Sungrow Power Supply Co Ltd
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Sungrow Power Supply Co Ltd
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    • 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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • 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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • 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
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention provides a voltage generating device and a high-frequency generation control method thereof, wherein in the voltage generating device, a power electronic conversion device is used for generating and outputting power frequency voltage; each phase line on the output side of the power electronic conversion device is connected with a corresponding high-frequency voltage generating unit in series to generate and output a high-frequency voltage; that is, the high-frequency voltage generating unit connected in series on each phase line of the output side of the high-frequency voltage generating unit is independently responsible for outputting the high-frequency voltage, so that the accuracy of the output high-frequency voltage is improved; the power electronic conversion device is not required to be responsible for generation and output of high-frequency voltage, and further is not required to improve the switching frequency of a power device, so that the switching loss of the power device is prevented from being increased, and the requirements of the prior art on device type selection and heat dissipation design of the original power electronic conversion device are prevented from being improved.

Description

Voltage generating device and high-frequency generation control method thereof
Technical Field
The invention relates to the technical field of power electronics, in particular to a voltage generating device and a high-frequency generation control method thereof.
Background
In some specific application occasions, the electrical equipment is required to output high-frequency harmonic voltage besides power frequency voltage; for example, the maximum harmonic frequency of the voltage to be output by the grid simulation device is 25, and the maximum harmonic frequency of the current to be compensated by the SVG (Static Var Generator) is 51.
In the prior art, a power electronic conversion device in electrical equipment is used for generating and outputting power frequency voltage and high frequency voltage; however, if the power electronic conversion device originally outputting the power frequency voltage is required to output the high-frequency voltage, the switching frequency of the power device of the power electronic conversion device is required to be increased, so that the switching loss of the power device is greatly increased, and the switching loss is particularly obvious in the high-power electronic conversion device; therefore, the currently adopted scheme inevitably brings difficulties to device type selection and heat dissipation design.
Disclosure of Invention
In view of the above, the present invention provides a voltage generating apparatus and a high frequency generation control method thereof, so as to improve the accuracy of the output high frequency voltage without affecting the device type selection and heat dissipation design of the original power electronic conversion apparatus.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a first aspect of the present invention provides a voltage generation apparatus, comprising: a power electronic conversion device and at least one high-frequency voltage generating unit; wherein:
the power electronic conversion device is used for generating and outputting power frequency voltage;
each of the high-frequency voltage generating units is connected in series to each phase line corresponding to an output side of the power electronic converter through an ac side thereof, and generates and outputs a high-frequency voltage;
the other side of the high-frequency voltage generating unit has no power input.
Optionally, the high-frequency voltage generating unit includes: at least one single-phase DC/AC conversion circuit;
a corresponding bus capacitor is arranged between the positive electrode and the negative electrode of the direct current side of the single-phase DC/AC conversion circuit;
when the high-frequency voltage generating unit comprises at least two single-phase DC/AC conversion circuits, the alternating current sides of the single-phase DC/AC conversion circuits are connected in a cascade mode, and the two cascaded ends are used as the alternating current sides of the high-frequency voltage generating unit.
Optionally, in the high-frequency voltage generating unit, the number of cascades of the single-phase DC/AC conversion circuits corresponds to a voltage class of the high-frequency voltage generating unit.
Optionally, the single-phase DC/AC conversion circuit includes: a two-level or three-level full-bridge topology or a half-bridge topology.
Optionally, the bus capacitor is further connected to a bleed-off loop.
Optionally, the power electronic conversion device is a static var generator SVG.
Optionally, each phase line of the output side of the SVG is respectively connected with the input end of the filter through one high-frequency voltage generating unit, and the output end of the filter is connected with the power grid through a corresponding transformer.
Optionally, the power electronic conversion device is an AC/AC converter with single-phase or three-phase output.
Optionally, the method further includes: a first transformer, a second transformer and a filter; wherein:
the input side of the AC/AC converter is connected with a power grid through the first transformer;
each phase line on the output side of the AC/AC converter is connected with the input end of the filter through one high-frequency voltage generating unit;
and the output end of the filter is connected with the tested equipment through the second transformer.
Optionally, the power electronic converter includes: generating a conversion branch of each phase of alternating current;
the conversion branch comprises: at least two single-phase AC/AC converters are cascaded through an output side.
Optionally, the method further includes: a split transformer and a third transformer; wherein:
the primary winding of the split transformer is connected with a power grid;
the input side of each single-phase AC/AC converter is connected with one secondary winding in the split transformer;
one end of the high-frequency voltage generating unit on each phase line is connected to the public end, and the other end of the high-frequency voltage generating unit is connected with one end of the transformation branch line of one phase respectively;
and the other end of each phase of the transformation branch circuit is connected with tested equipment through the third transformer.
Optionally, the power electronic conversion device is a three-phase conversion device.
Optionally, the power electronic converter is further configured to generate and output a harmonic voltage with a preset frequency, where the preset frequency is lower than the frequency of the high-frequency voltage.
A second aspect of the present invention provides a high-frequency generation control method for a voltage generation device, where the voltage generation device is the voltage generation device described in any one of the above paragraphs of the first aspect; the high-frequency voltage generating unit includes: at least one single-phase DC/AC conversion circuit; the high-frequency generation control method includes, for the single-phase DC/AC conversion circuit:
determining the modulation voltage of a bus voltage stabilizing control loop of the single-phase DC/AC conversion circuit by taking the bus voltage at the direct current side of the single-phase DC/AC conversion circuit as a target to be stabilized at a given value;
determining the harmonic modulation amount of the single-phase DC/AC conversion circuit according to the harmonic given voltage of the single-phase DC/AC conversion circuit;
and executing a PWM algorithm according to the sum of the modulation voltage and the harmonic modulation amount, and controlling the single-phase DC/AC conversion circuit to output corresponding high-frequency voltage.
Optionally, the determining the modulation voltage of the bus regulation control loop of the single-phase DC/AC conversion circuit with a target of stabilizing the bus voltage at the DC side of the single-phase DC/AC conversion circuit at a given value includes:
performing PI regulation according to the difference value between the given value and the actual value of the bus voltage to obtain a reference value of the bus current of the single-phase DC/AC conversion circuit;
determining an output modulation ratio of the single-phase DC/AC conversion circuit according to the reference value of the bus current and the amplitude of the output current of the single-phase DC/AC conversion circuit;
and determining the modulation voltage according to the phase trigonometric function of the output modulation ratio and the output current.
Optionally, when the high-frequency voltage generating unit is not required to output the high-frequency voltage, the harmonic given voltage is zero, or the harmonic given voltage and the given value of the bus voltage are both zero.
The invention provides a voltage generating device, wherein a power electronic conversion device is used for generating and outputting power frequency voltage; each phase line on the output side of the power electronic conversion device is connected with a corresponding high-frequency voltage generating unit in series to generate and output a high-frequency voltage; that is, the high-frequency voltage generating unit connected in series on each phase line of the output side of the high-frequency voltage generating unit is independently responsible for outputting the high-frequency voltage, so that the accuracy of the output high-frequency voltage is improved; the power electronic conversion device is not required to be responsible for generation and output of high-frequency voltage, and further is not required to improve the switching frequency of a power device, so that the switching loss of the power device is prevented from being increased, and the requirements of the prior art on device type selection and heat dissipation design of the original power electronic conversion device are prevented from being improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 and fig. 2 are schematic structural diagrams of two voltage generation devices provided in an embodiment of the present invention;
fig. 3a, fig. 3b, fig. 3c, fig. 3d, fig. 3e and fig. 3f are six topological diagrams of the DC/AC converting circuit in the high-frequency voltage generating unit according to the embodiment of the present invention;
FIG. 4 is a schematic diagram of an application of a DC/AC converting circuit in the high-frequency voltage generating unit according to the embodiment of the present invention;
fig. 5 to fig. 7 are schematic diagrams of three application structures of the voltage generating device according to the embodiment of the invention;
fig. 8 is a flowchart of a high-frequency generation control method of a voltage generation device according to an embodiment of the present invention;
fig. 9 is a schematic diagram illustrating positive direction identifiers of parameters of a two-level single-phase H-bridge according to an embodiment of the present invention when the two-level single-phase H-bridge is used as a topology of a DC/AC conversion circuit of a high-frequency voltage generation unit;
fig. 10 is a control block diagram of the voltage generation device according to the embodiment of the present invention.
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.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The invention provides a voltage generating device, which is used for enabling the precision of output high-frequency voltage to meet the national standard requirement on the basis of not influencing the device model selection and the heat dissipation design of the original power electronic conversion device.
As shown in fig. 1, the voltage generation apparatus includes: a power electronic converter 101 and at least one high-frequency voltage generating unit 102; wherein:
the power electronic conversion device 101 is used for generating and outputting power frequency voltage; in practical applications, the power electronic converter 101 may be a three-phase converter as shown in fig. 1 or a single-phase converter as shown in fig. 2; depending on the specific application environment, are all within the scope of the present application.
The high-frequency voltage generating units 102 are connected in series to the output-side phase lines of the power electronic converter 101 via the ac sides thereof. In the three-phase inverter shown in fig. 1, a corresponding high-frequency voltage generating unit 102 is connected in series to each of the U, V, W phase lines; in the single-phase inverter shown in fig. 2, only one high-frequency voltage generating unit 102 may be connected in series to the phase line L.
The high-frequency voltage generating unit 102 is configured to generate and output a high-frequency voltage. In practical applications, the power electronic converter 101 may further generate and output a harmonic voltage with a preset frequency according to actual requirements, and the preset frequency is lower than the frequency of the high-frequency voltage.
That is, the power electronic converter 101 can only output power frequency voltage and harmonic voltage with a low frequency, and has no high-frequency voltage output capability; and the high-frequency voltage generating unit 102 added is exclusively for generating harmonic voltages.
In order to improve the precision of the high-frequency voltage, the voltage generating device provided by this embodiment additionally adds the high-frequency voltage generating unit 102 to the original power electronic conversion device 101 to independently take charge of outputting the high-frequency voltage and improve the precision of the output high-frequency voltage; the power electronic conversion device 101 does not need to be responsible for generation and output of high-frequency voltage, and further does not need to improve the switching frequency of a power device, so that the switching loss of the power device is prevented from being increased, and the requirements of the prior art on device type selection and heat dissipation design of the original power electronic conversion device 101 are prevented from being improved. That is, the voltage generator according to the present embodiment can improve the accuracy of the high-frequency voltage output from the system without affecting the design of the power electronic converter 101. Moreover, the other side of the high-frequency voltage generating unit 102 has no power input, i.e. it does not need any secondary winding of a transformer to provide a front-end power support, and thus the above-mentioned functions can be achieved.
On the basis of the above embodiment, the high-frequency voltage generating unit 102 may include only one single-phase DC/AC converting circuit; the single-phase DC/AC conversion circuit is connected with a corresponding phase line in series through two poles at the AC side; and a corresponding bus capacitor is arranged between the positive electrode and the negative electrode on the direct current side of the single-phase DC/AC conversion circuit.
In practical application, the single-phase DC/AC conversion circuit can adopt the following steps: a two-level or three-level full-bridge topology or a half-bridge topology as shown in fig. 3a to 3 f.
When the output high-frequency voltage is not needed, the single-phase DC/AC conversion circuit can work in two states: firstly, outputting zero level, naturally discharging the bus voltage at the direct current side, charging the bus voltage to a given value when high-frequency voltage needs to be output, and putting the bus voltage into normal operation; secondly, the bus voltage is kept stable by only outputting fundamental frequency voltage (namely, power frequency voltage) in normal work, so that the output high-frequency voltage is zero.
The single-phase DC/AC conversion circuit does not provide or absorb active power generated by power frequency except the unit and harmonic loss. Besides outputting harmonic voltage, the single-phase DC/AC conversion circuit can superpose and output a voltage which has a phase opposite to that of output power frequency current and a very low amplitude on the output harmonic voltage in order to charge the bus voltage and stabilize the bus voltage to a given value, and the control scheme can refer to the following high-frequency generation control method. The single-phase DC/AC conversion circuit has low output voltage, low bus voltage, and can select switching tube with low voltage resistance, such as IGBT, and increase switching frequency.
In addition, in practical application, a plurality of single-phase DC/AC conversion circuits with the above-mentioned structure may be cascaded to form one high-frequency voltage generating unit 102 (as shown in fig. 1 and fig. 2), that is, each high-frequency voltage generating unit 102 includes at least two single-phase DC/AC conversion circuits, the AC sides of the single-phase DC/AC conversion circuits are cascaded, and the two cascaded ends are used as the AC sides of the high-frequency voltage generating unit 102 and are connected in series to the corresponding phase line, so as to improve the equivalent switching frequency of the high-frequency generating portion, and make the waveform quality and precision of the harmonic voltage meet the national standard requirements. In practical application, the cascade number of the single-phase DC/AC conversion circuits inside the high-frequency voltage generating unit 102 can be determined according to the voltage level that the high-frequency voltage generating unit needs to reach; depending on the specific application environment, are all within the scope of the present application.
Furthermore, more preferably, in order to prevent the pumping of the bus voltage of the single-phase DC/AC conversion circuit in some special cases, a bleeding circuit may be connected in parallel to the bus capacitor of the single-phase DC/AC conversion circuit; the bleeder circuit may be specifically composed of a discharge resistor and a switch connected in series, and the discharge resistor may be an independent resistor or a series-parallel connection form of a plurality of resistors, which is shown in fig. 4 as one of the optional forms, but is not limited thereto.
The voltage generating devices described in the above embodiments may constitute devices of different nature when applied to different applications.
For example, referring to fig. 5, when the power electronic conversion device 101 is an SVG, each phase line of the output side of the SVG is connected to the input end of the filter through a high-frequency voltage generating unit 102 (fig. 5 shows a three-phase structure as an example), and the output end of the filter is connected to the power grid through a corresponding transformer; and furthermore, the SVG can ensure that harmonic current with higher times, such as 51 times, can be compensated under the condition that the requirements of device model selection and heat dissipation design are lower.
For another example, referring to fig. 6, the power electronic converter 101 is an AC/AC converter with single-phase or three-phase output, and the input side of the AC/AC converter is connected to the power grid through a first transformer 201, and the phases of the output side of the AC/AC converter are connected to the input end of the filter through a high-frequency voltage generating unit 102; the output of the filter is connected to the device under test via a second transformer 202.
For another example, referring to fig. 7, the power electronic converter 101 includes: a conversion branch 301 for generating each phase of alternating current; the conversion branch 301 includes: at least two single-phase AC/AC converters are cascaded through an output side. The input side of each single-phase AC/AC converter is connected with one secondary winding in the split transformer 302; the primary winding of the split transformer 302 is connected to the grid; one end of the high-frequency voltage generating unit 102 on each phase line is connected to the common end, and the other end of the high-frequency voltage generating unit is connected with one end of a phase-change branch 301 respectively; the other end of each phase conversion branch 301 is connected with the device to be tested through a third transformer 303. By the two modes, the power grid simulation device suitable for different powers and different voltage levels can be formed.
That is, this voltage generation device that this embodiment provided simple structure, control are simple, easily realize the modularization, can be applied to in three-phase electric wire netting analogue means and SVG, have guaranteed the output precision of system harmonic voltage, have reduced the cost and the weight of device.
Another embodiment of the present invention further provides a high frequency generation control method for a voltage generation device, where the voltage generation device is the voltage generation device according to any of the above embodiments; the high frequency voltage generating unit comprises: at least one single-phase DC/AC conversion circuit. The structure and connection relationship of the voltage generating device can be seen in the above embodiments, and are not described in detail here.
The high frequency generation control method, as shown in fig. 8, includes, for a single-phase DC/AC conversion circuit:
s101, aiming at stabilizing the bus voltage at the direct current side of the single-phase DC/AC conversion circuit to a given value, determining the modulation voltage of a bus voltage stabilizing control loop of the single-phase DC/AC conversion circuit.
The step S101 may specifically include:
(1) and calculating the difference value between the given value and the actual value of the bus voltage of the single-phase DC/AC conversion circuit, and performing PI regulation on the difference value to obtain the reference value of the bus current of the single-phase DC/AC conversion circuit.
(2) According to the output current of the single-phase DC/AC conversion circuit, the amplitude of the output current and a trigonometric function of the phase opposite to the output current are determined.
(3) And calculating the quotient of the reference value of the bus current divided by the amplitude of the output current to obtain the output modulation ratio of the single-phase DC/AC conversion circuit.
(4) And calculating the product of the output modulation ratio and the trigonometric function to obtain the modulation voltage of the bus voltage stabilization control loop.
S102, determining the harmonic modulation amount of the single-phase DC/AC conversion circuit according to the harmonic given voltage of the single-phase DC/AC conversion circuit.
The step may specifically be: the harmonic given voltage is divided by the given value of the bus voltage to calculate the quotient as the harmonic modulation amount.
And S103, executing a PWM algorithm according to the sum of the modulation voltage and the harmonic modulation amount, and controlling the single-phase DC/AC conversion circuit to output corresponding high-frequency voltage.
Executing a PWM algorithm according to the sum of the modulation voltage and the harmonic modulation quantity to obtain a modulation wave of the single-phase DC/AC conversion circuit; then, the power tube in the single-phase DC/AC conversion circuit is driven by the modulation wave to operate, and then the corresponding high-frequency voltage is output.
Taking the topology of a single-phase DC/AC conversion circuit having a two-level single-phase H-bridge as the high-frequency voltage generating unit 102 shown in FIG. 9 as an example, the output current i thereofoutOutput voltage uoutBus current idcBus voltage udcThe positive direction of (a) is defined as shown in fig. 9. It should be noted that, since the alternating current can be transmitted in both directions, any direction of the current can be selected for definition, and for convenience of explaining the principle, the output current i is shown in fig. 9outIs defined as the positive direction of (c), as opposed to the actual situation.
The output current of the two-level single-phase H-bridge is assumed to be:
iout＝I cos(ωt) (1)
according to
udcidc＝uoutiout (2)
uout＝mcudccos(ωt) (3)
Wherein m iscIs the H-bridge modulation ratio. The bus current can be obtained according to equations (1), (2) and (3):
Figure BDA0003396435830000091
a modulation ratio of:
Figure BDA0003396435830000092
wherein, IdcIs the average value of the bus current, and omega is the output voltage uoutT is time.
Specific control block diagrams can be seen in fig. 10:
firstly, the actual value u of the bus voltage is calculateddcWith a given value UdcComparing, and obtaining a reference value I of the bus current after PI regulationdcDividing the output current amplitude I to obtain an output modulation ratio mc*。
Extracting an output current ioutThen extracting the orthogonal component of the fundamental component to obtain the amplitude of the output current
Figure BDA0003396435830000093
And determines the output current io according to the fundamental component and the orthogonal component thereofutA trigonometric function of the same phase, i.e. a trigonometric function of the opposite phase to the actual output current.
Output modulation ratio mcMultiplying the trigonometric function to obtain the modulation voltage u of the bus voltage-stabilizing control loopc*。
Harmonic given voltage u, on the other handhramGiven value U divided by bus voltagedcThe quotient of x is taken as the harmonic modulation quantity.
Then, the modulation voltage u of the bus voltage stabilization control loop is adjustedcAnd the harmonic modulation amount, and performing summation calculation to obtain the sum umAnd executing a PWM algorithm to obtain a modulation wave of the single-phase DC/AC conversion circuit.
In practical applications, it is preferable that the actual value u of the bus voltage is first compared to the actual value u as shown in fig. 10dcFiltering is performed to eliminate a ripple component in the actual value of the bus voltage. That is, the actual value u of the dc bus voltage shown in fig. 10dcThe Filter of (2) aims at filtering out ripple components on the bus voltage. When the H-bridge outputs harmonic voltage or the output current contains larger harmonicDuring the component, can produce the ripple voltage of fundamental frequency multiple on bus capacitor, the low frequency ripple voltage on the generating line can produce the influence to the modulation voltage of generating line steady voltage ring after PI enlargies, makes the H bridge contain a large amount of harmonic voltage in being used for the output voltage of generating line steady voltage, influences entire system's output voltage quality. The bus voltage can be filtered by a low-pass filter, a band-stop filter, a delay elimination filter, a moving average filter and the like.
In addition, in order to prevent the dynamic response of the busbar stabilizer ring and the quality of the output modulation wave from being affected when the harmonic content in the output current is large, it is necessary to extract the fundamental component of the output current. In order to obtain the amplitude of the fundamental component of the output current, it is also necessary to extract the quadrature component of the fundamental current. The extraction of the current fundamental wave component and the fundamental wave orthogonal component can adopt methods such as a second-order band-pass filter and a second-order low-pass filter, a second-order generalized integral, a notch filter based on a moving average filter and the like.
When the high-frequency voltage generating means is required to output the high-frequency voltage, the harmonic thereof is given by the voltage uhramGiven value U of sum bus voltagedcEach has a respective value. In practical application, if the high-frequency voltage generating unit is not required to output the high-frequency voltage, the high-frequency voltage output by the single-phase DC/AC conversion circuit can be controlled to be zero, and only the corresponding fundamental frequency voltage (i.e., power frequency voltage) is output, so that the bus voltage on the direct current side of the single-phase DC/AC conversion circuit is stabilized at a given value, and the output high-frequency voltage is zero; at this time, its harmonic wave gives a voltage uhramIs zero, given value of bus voltage UdcKeep its corresponding value. Alternatively, when the high-frequency voltage generating unit is not required to output the high-frequency voltage, the single-phase DC/AC converting circuit may be controlled to output a zero level, in which case the harmonic thereof is given by the voltage uhramGiven value U of sum bus voltagedcAnd all the bus voltages are zero, the bus voltage on the direct current side is naturally discharged, and the bus voltage is charged to a given value and put into normal operation when high-frequency voltage needs to be output.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (16)

1. A voltage generation device, comprising: a power electronic conversion device and at least one high-frequency voltage generating unit; wherein:
the power electronic conversion device is used for generating and outputting power frequency voltage;
each of the high-frequency voltage generating units is connected in series to each phase line corresponding to an output side of the power electronic converter through an ac side thereof, and generates and outputs a high-frequency voltage;
the other side of the high-frequency voltage generating unit has no power input.
2. The voltage generation device according to claim 1, wherein the high-frequency voltage generation unit includes: at least one single-phase DC/AC conversion circuit;
a corresponding bus capacitor is arranged between the positive electrode and the negative electrode of the direct current side of the single-phase DC/AC conversion circuit;
when the high-frequency voltage generating unit comprises at least two single-phase DC/AC conversion circuits, the alternating current sides of the single-phase DC/AC conversion circuits are connected in a cascade mode, and the two cascaded ends are used as the alternating current sides of the high-frequency voltage generating unit.
3. The voltage generation apparatus according to claim 2, wherein the number of stages of the single-phase DC/AC conversion circuit in the high-frequency voltage generation unit corresponds to a voltage class of the high-frequency voltage generation unit.
4. The voltage generation apparatus of claim 2, wherein the single-phase DC/AC conversion circuit is: a two-level or three-level full-bridge topology or a half-bridge topology.
5. The voltage generating device of claim 2, wherein the bus capacitor is further connected to a bleed circuit.
6. Voltage generation device according to any one of claims 1 to 5, characterized in that said power electronic converter means are Static Var Generators (SVG).
7. The voltage generation device according to claim 6, wherein the output side phase lines of the SVG are connected to the input end of a filter through one of the high-frequency voltage generation units, respectively, and the output end of the filter is connected to the power grid through a corresponding transformer.
8. A voltage generation arrangement according to any of claims 1 to 5 wherein the power electronic converter is a single phase or three phase output AC/AC converter.
9. The voltage generation device according to claim 8, further comprising: a first transformer, a second transformer and a filter; wherein:
the input side of the AC/AC converter is connected with a power grid through the first transformer;
each phase line on the output side of the AC/AC converter is connected with the input end of the filter through one high-frequency voltage generating unit;
and the output end of the filter is connected with the tested equipment through the second transformer.
10. A voltage generation device according to any one of claims 1 to 5, characterized in that the power electronic converter device comprises: generating a conversion branch of each phase of alternating current;
the conversion branch comprises: at least two single-phase AC/AC converters are cascaded through an output side.
11. The voltage generation apparatus of claim 10, further comprising: a split transformer and a third transformer; wherein:
the primary winding of the split transformer is connected with a power grid;
the input side of each single-phase AC/AC converter is connected with one secondary winding in the split transformer;
one end of the high-frequency voltage generating unit on each phase line is connected to the public end, and the other end of the high-frequency voltage generating unit is connected with one end of the transformation branch line of one phase respectively;
and the other end of each phase of the transformation branch circuit is connected with tested equipment through the third transformer.
12. A voltage generation device according to any one of claims 1 to 5, wherein the power electronic conversion device is a three-phase conversion device.
13. The voltage generation device according to any one of claims 1 to 5, wherein the power electronic converter device is further configured to generate and output a harmonic voltage of a preset frequency, the preset frequency being lower than the frequency of the high-frequency voltage.
14. A high-frequency generation control method of a voltage generation device, characterized in that the voltage generation device is the voltage generation device according to any one of claims 1 to 13; the high-frequency voltage generating unit includes: at least one single-phase DC/AC conversion circuit; the high-frequency generation control method includes, for the single-phase DC/AC conversion circuit:
determining the modulation voltage of a bus voltage stabilizing control loop of the single-phase DC/AC conversion circuit by taking the bus voltage at the direct current side of the single-phase DC/AC conversion circuit as a target to be stabilized at a given value;
determining the harmonic modulation amount of the single-phase DC/AC conversion circuit according to the harmonic given voltage of the single-phase DC/AC conversion circuit;
and executing a PWM algorithm according to the sum of the modulation voltage and the harmonic modulation amount, and controlling the single-phase DC/AC conversion circuit to output corresponding high-frequency voltage.
15. The high-frequency generation control method of a voltage generating apparatus according to claim 14, wherein determining the modulation voltage of the bus regulator control loop of the single-phase DC/AC conversion circuit with a target of stabilizing the bus voltage on the DC side of the single-phase DC/AC conversion circuit at a given value includes:
performing PI regulation according to the difference value between the given value and the actual value of the bus voltage to obtain a reference value of the bus current of the single-phase DC/AC conversion circuit;
determining an output modulation ratio of the single-phase DC/AC conversion circuit according to the reference value of the bus current and the amplitude of the output current of the single-phase DC/AC conversion circuit;
and determining the modulation voltage according to the phase trigonometric function of the output modulation ratio and the output current.
16. A high-frequency generation control method of a voltage generation device according to claim 14 or 15, wherein the harmonic given voltage is zero or the given values of the harmonic given voltage and the bus voltage are both zero when there is no need for the high-frequency voltage generation unit to output a high-frequency voltage.
CN202111485686.4A 2021-12-07 2021-12-07 Voltage generating device and high-frequency generation control method thereof Pending CN114172166A (en)

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