CN117060498A - Virtual node voltage feedback control method and system of inverter - Google Patents

Virtual node voltage feedback control method and system of inverter Download PDF

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Publication number
CN117060498A
CN117060498A CN202310862869.6A CN202310862869A CN117060498A CN 117060498 A CN117060498 A CN 117060498A CN 202310862869 A CN202310862869 A CN 202310862869A CN 117060498 A CN117060498 A CN 117060498A
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China
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voltage
value
component
current
virtual node
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Inventor
葛路明
朱凌志
汤涌
吴福保
曲立楠
陈宁
姜达军
张红颖
贾一超
彭佩佩
何洁琼
丛从
胡哲
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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Priority to CN202310862869.6A priority Critical patent/CN117060498A/en
Publication of CN117060498A publication Critical patent/CN117060498A/en
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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
    • H02J3/38—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
    • 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
    • H02J3/381—Dispersed generators
    • 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

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

Abstract

The invention provides a virtual node voltage feedback control method and a system of an inverter, comprising the following steps: calculating a reference value of the virtual node voltage by using a current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current; calculating a modulation voltage value without a filter capacitor current feedback term by using a voltage controller based on the reference value of the virtual node voltage and the calculated value of the virtual node voltage; calculating a pulse modulation voltage based on a modulation voltage value without a filter capacitor current feedback term and a current actual value of a filter capacitor; the invention introduces the voltage of the virtual node as an intermediate quantity, and completes the on-off of the bridge arm in the inverter by calculating according to the grid-connected current and the current of the filter capacitor in real time, thereby realizing the improvement of the stability of the inverter without adding an additional voltage sensor and being beneficial to reducing the cost of the inverter.

Description

Virtual node voltage feedback control method and system of inverter
Technical Field
The invention belongs to the technical field of new energy power generation of power systems, and particularly relates to a virtual node voltage feedback control method and system of an inverter.
Background
At present, the aim of wind power and photovoltaic installation reaches more than 12 hundred million kilowatts when new energy is met, a large number of new energy power stations are generally connected into a large power grid in a boosting mode of a 3-4-level transformer, so that the electrical distance between the new energy power stations and the large power grid is far, the power grid strength is weak, and the adaptability of the new energy power stations to the weak power grid is improved greatly.
The inverter has better control performance in a strong power grid generally, has smaller output current harmonic wave and can stably run. However, in a weak grid, because the grid lacks voltage support, the grid voltage is easy to be influenced by the output current of the inverter to generate fluctuation, so that the stability of the inverter is reduced, a large number of harmonic waves appear on the voltage and the current, and an overvoltage and overcurrent phenomenon can be caused. Therefore, the inverter cannot stably operate, and risks are brought to safe and stable operation of the power grid.
At present, for smooth operation of the inverter, a capacitor voltage feedback mode may be adopted. The voltage of the filter capacitor in the inverter is subjected to feedback control, but the method not only needs to measure the grid-connected voltage of the inverter in real time, but also needs to measure the new feedback quantity introduced by the voltage of the filter capacitor, and an additional capacitor voltage sensor is needed, so that the hardware cost and the structural complexity of the inverter are increased.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a virtual node voltage feedback control method of an inverter, which comprises the following steps:
calculating a reference value of the virtual node voltage by using a current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current;
calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period;
calculating a pulse modulation voltage based on a modulation voltage value without a filter capacitor current feedback term and a current actual value of a filter capacitor;
modulating the pulse modulation voltage to obtain a pulse signal, and driving the bridge arm in the inverter to be disconnected by the pulse signal, thereby completing one cycle.
Preferably, the calculating of the reference value of the virtual node voltage and the calculating of the modulation voltage value without the filter capacitor current feedback term are both completed in a dq synchronous rotation coordinate system;
the calculation of the pulse modulation voltage is completed in an abc three-phase static coordinate system;
after the calculating of the modulation voltage value without the filter capacitor current feedback term and before the calculating of the pulse modulation voltage, the method further comprises:
and transforming the modulation voltage value without the filter capacitor current feedback item from the dq synchronous rotation coordinate system to the abc three-phase static coordinate system.
Preferably, the reference value of the virtual node voltage is calculated by the following calculation formula:
wherein u is vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H i For the current feedback coefficient, G i (s) is a current controller, i dref I is the component of the reference value of the grid-connected current in the d axis qref K being the component of the reference value of the grid-connected current on the q-axis dcp Decoupling coefficient i for dq synchronous rotation coordinate system d I is the component of the actual value of the grid-connected current in the d-axis q Is the component of the actual value of the grid-connected current on the q-axis.
Preferably, the modulation voltage value without the filter capacitor current feedback term is calculated by the following calculation formula:
wherein u is md1 For the component of the modulation voltage value in the d-axis without the filter capacitance current feedback term, u mq1 For the component of the modulation voltage value on the q-axis without the filter capacitor current feedback term, G u (s) is a voltage controller, u vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H u As the current feedback coefficient, u vd For the component of the calculated value of the virtual node voltage on the d-axis, u vq Is the component of the calculated value of the virtual node voltage on the q-axis.
Preferably, the pulse modulation voltage is calculated by the following calculation formula:
wherein u is ma For pulsing the component of the voltage in phase a, u mb U is the component of the pulse modulated voltage in phase b mc For pulsing the component of the voltage in phase c, u ma1 For the component of the modulation voltage value in phase a without the filter capacitor current feedback term, u mb1 For the component of the modulation voltage value in phase b without the filter capacitance current feedback term, u mc1 For the component of the modulating voltage value in phase c, i without the filter capacitor current feedback term Ca I is the component of the actual value of the current of the filter capacitor in the a phase Cb I is the component of the actual value of the current of the filter capacitor in phase b Cc For the component of the actual value of the current of the filter capacitor in phase c, K ic Is the current feedback coefficient of the filter capacitor.
Preferably, the calculating value of the virtual node voltage calculated according to the actual value of the grid-connected voltage and the actual value of the grid-connected current includes:
calculating a calculated value of the virtual node voltage according to the actual value of the grid-connected voltage and the actual value of the grid-connected current in the abc three-phase static coordinate system;
and transforming the calculated value of the virtual node voltage from the abc three-phase static coordinate system to the dq synchronous rotation coordinate system.
Preferably, the calculated value of the virtual node voltage is calculated by the following calculation formula:
wherein u is va Calculated value for virtual node voltageIn the component of phase a, u vb For the component of the calculated value of the virtual node voltage in phase b, u vc For the component of the calculated value of the virtual node voltage in phase c, u ta For the component of the actual value of the grid-connected voltage in phase a, u tb For the component of the actual value of the grid-connected voltage in phase b, u tc I is the component of the actual value of the grid-connected voltage in the c phase a I is the component of the actual value of the grid-connected current in phase a b I is the component of the actual value of the grid-connected current in phase b c For the component of the actual value of the grid-connected current in phase c, L v Is a virtual inductance value.
Based on the same inventive concept, the invention also provides a virtual node voltage feedback control system of the inverter, comprising:
the grid-connected current outer loop control module is used for calculating a reference value of the virtual node voltage by using the current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current;
the virtual node voltage inner loop control module is used for calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period;
the capacitor current inner loop control module is used for calculating pulse modulation voltage based on the modulation voltage value without a filter capacitor current feedback item and the actual current value of the filter capacitor;
and the bridge arm pulse driving control module is used for modulating the pulse modulation voltage to obtain a pulse signal, and driving the bridge arm in the inverter to be disconnected by the pulse signal so as to complete one cycle.
Preferably, the grid-connected current outer loop control module calculates a reference value of virtual node voltage and the virtual node voltage inner loop control module calculates a modulation voltage value without a filter capacitor current feedback item in a dq synchronous rotation coordinate system;
the capacitor current inner loop control module calculates the pulse modulation voltage to be completed in an abc three-phase static coordinate system;
after the virtual node voltage inner loop control module calculates the modulation voltage value without the filtering capacitor current feedback item and before the capacitor current inner loop control module calculates the pulse modulation voltage, the method further comprises the following steps:
and transforming the modulation voltage value without the filter capacitor current feedback item from the dq synchronous rotation coordinate system to the abc three-phase static coordinate system.
Preferably, the reference value of the virtual node voltage in the grid-connected current outer loop control module is calculated by the following calculation formula:
wherein u is vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H i For the current feedback coefficient, G i (s) is a current controller, i dref I is the component of the reference value of the grid-connected current in the d axis qref K being the component of the reference value of the grid-connected current on the q-axis dcp Decoupling coefficient i for dq synchronous rotation coordinate system d I is the component of the actual value of the grid-connected current in the d-axis q Is the component of the actual value of the grid-connected current on the q-axis.
Preferably, the modulation voltage value of the virtual node voltage inner loop control module without the filter capacitor current feedback term is calculated by the following calculation formula:
wherein u is md1 For the component of the modulation voltage value in the d-axis without the filter capacitance current feedback term, u mq1 For the component of the modulation voltage value on the q axis without the filter capacitor current feedback term, gu(s) is a voltage controller, u vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H u As the current feedback coefficient, u vd For the component of the calculated value of the virtual node voltage on the d-axis, u vq Is the component of the calculated value of the virtual node voltage on the q-axis.
Preferably, the pulse modulation voltage in the capacitive current inner loop control module is calculated by the following calculation formula:
wherein u is ma For pulsing the component of the voltage in phase a, u mb U is the component of the pulse modulated voltage in phase b mc For pulsing the component of the voltage in phase c, u ma1 For the component of the modulation voltage value in phase a without the filter capacitor current feedback term, u mb1 For the component of the modulation voltage value in phase b without the filter capacitance current feedback term, u mc1 For the component of the modulating voltage value in phase c, i without the filter capacitor current feedback term Ca I is the component of the actual value of the current of the filter capacitor in the a phase Cb I is the component of the actual value of the current of the filter capacitor in phase b Cc For the component of the actual value of the current of the filter capacitor in phase c, K ic Is the current feedback coefficient of the filter capacitor.
Preferably, the virtual node voltage inner loop control module calculates a calculated value of the virtual node voltage according to an actual value of the grid-connected voltage and an actual value of the grid-connected current, and the calculated value comprises:
calculating a calculated value of the virtual node voltage according to the actual value of the grid-connected voltage and the actual value of the grid-connected current in the abc three-phase static coordinate system;
and transforming the calculated value of the virtual node voltage from the abc three-phase static coordinate system to the dq synchronous rotation coordinate system.
Preferably, the calculated value of the virtual node voltage in the virtual node voltage inner loop control module is calculated by the following calculation formula:
wherein u is va For the component of the calculated value of the virtual node voltage in phase a, u vb For the component of the calculated value of the virtual node voltage in phase b, u vc For the component of the calculated value of the virtual node voltage in phase c, u ta For the component of the actual value of the grid-connected voltage in phase a, u tb For the component of the actual value of the grid-connected voltage in phase b, u tc I is the component of the actual value of the grid-connected voltage in the c phase a I is the component of the actual value of the grid-connected current in phase a b I is the component of the actual value of the grid-connected current in phase b c For the component of the actual value of the grid-connected current in phase c, L v Is a virtual inductance value.
Compared with the closest prior art, the invention has the following beneficial effects:
the invention provides a virtual node voltage feedback control method and a system of an inverter, comprising the following steps: calculating a reference value of the virtual node voltage by using a current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current; calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period; calculating a pulse modulation voltage based on a modulation voltage value without a filter capacitor current feedback term and a current actual value of a filter capacitor; the pulse modulation voltage is modulated to obtain a pulse signal, and the pulse signal drives the bridge arm in the inverter to be disconnected, so that one cycle is completed.
Drawings
Fig. 1 is a schematic flow chart of a virtual node voltage feedback control method of an inverter according to the present invention;
FIG. 2 is a schematic diagram of a virtual node voltage feedback control circuit of an inverter according to the present invention;
FIG. 3 is a voltage-current waveform diagram of an inverter in a weak grid environment according to the present invention;
FIG. 4 is a graph showing the voltage and current waveforms of the inverter in a weak grid environment with harmonics according to the present invention;
fig. 5 is a schematic structural diagram of a virtual node voltage feedback control system of an inverter according to the present invention.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
Example 1:
the invention provides a virtual node voltage feedback control method of an inverter, as shown in fig. 1, comprising the following steps:
step 1: calculating a reference value of the virtual node voltage by using a current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current;
step 2: calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period;
step 3: calculating a pulse modulation voltage based on a modulation voltage value without a filter capacitor current feedback term and a current actual value of a filter capacitor;
step 4: modulating the pulse modulation voltage to obtain a pulse signal, and driving the bridge arm in the inverter to be disconnected by the pulse signal, thereby completing one cycle.
The steps 1-4 are part of a period, and voltage feedback is performed in real time. The reference value of the virtual node voltage is calculated, and the modulation voltage value without the filtering capacitor current feedback item is calculated in a dq synchronous rotation coordinate system; the calculation of the pulse modulation voltage is completed in an abc three-phase static coordinate system.
After the calculating of the modulation voltage value without the filter capacitor current feedback term and before the calculating of the pulse modulation voltage, the method further comprises:
and the modulating voltage value without the filtering capacitor current feedback item is transformed from the dq synchronous rotation coordinate system to the abc three-phase static coordinate system.
Before the period starts and the step 1 is performed, namely, when the period starts, at this time, the voltage of the grid-connected end of the inverter is firstly collected, the phase angle theta of the grid-connected voltage of the inverter is measured by using a phase-locked loop in the inverter (the phase angle theta is used for performing coordinate system conversion), and then the calculated value of the virtual node voltage is calculated according to the actual value of the grid-connected voltage and the actual value of the grid-connected current.
The calculated value of the virtual node voltage calculated according to the actual value of the grid-connected voltage and the actual value of the grid-connected current comprises the following steps:
the method comprises the steps that a calculated value of a virtual node voltage is calculated according to an actual value of a grid-connected voltage and an actual value of a grid-connected current in an abc three-phase static coordinate system;
and the calculated value of the virtual node voltage is transformed from the abc three-phase static coordinate system to the dq synchronous rotation coordinate system.
Wherein the calculated value of the virtual node voltage (in the abc three-phase stationary coordinate system) is calculated by the following calculation formula:
wherein u is va For the component of the calculated value of the virtual node voltage in phase a, u vb For the component of the calculated value of the virtual node voltage in phase b, u vc For the component of the calculated value of the virtual node voltage in phase c, u ta For the component of the actual value of the grid-connected voltage in phase a, u tb For the component of the actual value of the grid-connected voltage in phase b, u tc I is the component of the actual value of the grid-connected voltage in the c phase a I is the component of the actual value of the grid-connected current in phase a b I is the component of the actual value of the grid-connected current in phase b c For the component of the actual value of the grid-connected current in phase c, L v Is a virtual inductance value.
The calculated value of the virtual node voltage (in the abc three-phase stationary coordinate system) is obtained, and the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current can be all transformed from the abc three-phase stationary coordinate system to the dq synchronous rotation coordinate system by using Park transformation based on the phase angle θ. Then, the operation of step 1 is performed.
In step 1, a reference value of the virtual node voltage is calculated using a current controller based on a reference value of the inverter grid-tie current and an actual value of the grid-tie current. The specific calculation mode is as follows:
the reference value of the virtual node voltage is calculated by the following calculation formula:
wherein u is vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H i For the current feedback coefficient, G i (s) is a current controller, i dref I is the component of the reference value of the grid-connected current in the d axis qref K being the component of the reference value of the grid-connected current on the q-axis dcp Decoupling coefficient i for dq synchronous rotation coordinate system d I is the component of the actual value of the grid-connected current in the d-axis q Is the component of the actual value of the grid-connected current on the q-axis.
In step 2, a voltage controller is used to calculate a modulation voltage value without a filter capacitor current feedback term based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period. The specific calculation mode is as follows:
the modulation voltage value without the filter capacitor current feedback term is calculated by the following calculation formula:
wherein u is md1 For the component of the modulation voltage value in the d-axis without the filter capacitance current feedback term, u mq1 For the component of the modulation voltage value on the q-axis without the filter capacitor current feedback term, G u (s) is a voltage controller, u vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H u As the current feedback coefficient, u vd For the component of the calculated value of the virtual node voltage on the d-axis, u vq Is the component of the calculated value of the virtual node voltage on the q-axis.
In step 3, a pulse modulation voltage is calculated based on the modulation voltage value without the filter capacitor current feedback term and the actual value of the filter capacitor current. The specific calculation mode is as follows:
the pulse modulation voltage is calculated by the following calculation formula:
wherein u is ma For pulsing the component of the voltage in phase a, u mb U is the component of the pulse modulated voltage in phase b mc For pulsing the component of the voltage in phase c, u ma1 For the component of the modulation voltage value in phase a without the filter capacitor current feedback term, u mb1 For the component of the modulation voltage value in phase b without the filter capacitance current feedback term, u mc1 For the component of the modulating voltage value in phase c, i without the filter capacitor current feedback term Ca I is the component of the actual value of the current of the filter capacitor in the a phase Cb I is the component of the actual value of the current of the filter capacitor in phase b Cc For the component of the actual value of the current of the filter capacitor in phase c, K ic Is the current feedback coefficient of the filter capacitor.
In step 4, the pulse modulation voltage (u ma 、u mb And u mc ) Obtaining a pulse signal and driving a middle bridge of the inverter by the pulse signalThe arms are turned on and off, thereby completing a cycle.
As shown in fig. 2, the present invention implements the above steps 1-4 by a circuit, wherein the upper part is a bridge arm part of the inverter, that is, a hardware part of the inverter, a non-control part, and the lower part is a control part, and the control part is executed in a controller of the inverter.
Under the extremely weak current network with the short circuit ratio of 1.5, as shown in fig. 3, the inverter can stably operate, and the total harmonic distortion (total harmonic distortion, THD) of the grid-connected voltage and the output current is very small. 3 times of harmonic waves (the harmonic content in the harmonic wave is 5%) and 5 times of harmonic waves (the harmonic content in the harmonic wave is 5%) are injected into the power grid at the same time, as shown in fig. 4, the inverter can still stably operate at the moment, the waveform sine degree of the output current is good, the harmonic distortion is small, and the control method has good weak power grid adaptability and harmonic suppression capability.
In summary, the control method includes 3 control closed loops, which are a grid-connected current outer loop (executed in step 1), a virtual node voltage inner loop (executed in step 2), and a capacitive current inner loop (executed in step 3) in order from outside to inside. The grid-connected current outer ring and the virtual node voltage inner ring are both established in a dq synchronous rotation coordinate system, and the reference phase angle of the rotation coordinate system is consistent with the phase of the grid voltage. The capacitive current inner loop is established in an abc three-phase stationary coordinate system. The input quantity of the grid-connected current outer ring is a grid-connected current reference value and a grid-connected current measured value, the output quantity is obtained after passing through a current controller, and the output quantity is a reference value of the virtual node voltage; the input quantity of the virtual node voltage inner loop is a virtual node voltage reference value and a virtual node voltage calculation value, the output quantity is obtained after the virtual node voltage inner loop passes through a voltage controller, and the output quantity is a modulation voltage without a capacitance current feedback item; the input quantity of the capacitive current inner loop is the modulation voltage and the capacitive current measured value without the capacitive current feedback item, and the output quantity of the capacitive current inner loop is the modulation voltage. The modulated voltage is modulated to obtain a pulse driving signal, and the pulse driving signal drives the on and off of the bridge arm of the inverter (step 4 is executed).
According to the invention, the virtual node voltage feedback loop is introduced, so that the stability of the inverter under the weak current network is improved, the virtual inductance is utilized to generate the electric distance, the controllability of the virtual node voltage is improved, an additional voltage sensor is not required to be added, and the cost is reduced.
Example 2:
based on the same inventive concept, the invention also provides a virtual node voltage feedback control system of the inverter, as shown in fig. 5, comprising:
the grid-connected current outer loop control module is used for calculating a reference value of the virtual node voltage by using the current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current;
the virtual node voltage inner loop control module is used for calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period;
the capacitor current inner loop control module is used for calculating pulse modulation voltage based on the modulation voltage value without a filter capacitor current feedback item and the actual current value of the filter capacitor;
and the bridge arm pulse driving control module is used for modulating the pulse modulation voltage to obtain a pulse signal, and driving the bridge arm in the inverter to be disconnected by the pulse signal so as to complete one cycle.
The grid-connected current outer ring control module calculates a reference value of virtual node voltage and the virtual node voltage inner ring control module calculates a modulation voltage value without a filter capacitor current feedback item in a dq synchronous rotation coordinate system;
the capacitor current inner loop control module calculates the pulse modulation voltage to be completed in an abc three-phase static coordinate system;
after the virtual node voltage inner loop control module calculates the modulation voltage value without the filtering capacitor current feedback item and before the capacitor current inner loop control module calculates the pulse modulation voltage, the method further comprises the following steps:
and the modulating voltage value without the filtering capacitor current feedback item is transformed from the dq synchronous rotation coordinate system to the abc three-phase static coordinate system.
The reference value of the virtual node voltage in the grid-connected current outer loop control module is calculated by the following calculation formula:
wherein u is vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H i For the current feedback coefficient, G i (s) is a current controller, i dref I is the component of the reference value of the grid-connected current in the d axis qref K being the component of the reference value of the grid-connected current on the q-axis dcp Decoupling coefficient i for dq synchronous rotation coordinate system d I is the component of the actual value of the grid-connected current in the d-axis q Is the component of the actual value of the grid-connected current on the q-axis.
The modulating voltage value without the filtering capacitor current feedback item in the virtual node voltage inner loop control module is calculated by the following calculation formula:
wherein u is md1 For the component of the modulation voltage value in the d-axis without the filter capacitance current feedback term, u mq1 For the component of the modulation voltage value on the q axis without the filter capacitor current feedback term, gu(s) is a voltage controller, u vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H u As the current feedback coefficient, u vd For the component of the calculated value of the virtual node voltage on the d-axis, u vq Is the component of the calculated value of the virtual node voltage on the q-axis.
The pulse modulation voltage in the capacitive current inner loop control module is calculated by the following calculation formula:
wherein u is ma For pulsing the component of the voltage in phase a, u mb U is the component of the pulse modulated voltage in phase b mc For pulsing the component of the voltage in phase c, u ma1 For the component of the modulation voltage value in phase a without the filter capacitor current feedback term, u mb1 For the component of the modulation voltage value in phase b without the filter capacitance current feedback term, u mc1 For the component of the modulating voltage value in phase c, i without the filter capacitor current feedback term Ca I is the component of the actual value of the current of the filter capacitor in the a phase Cb I is the component of the actual value of the current of the filter capacitor in phase b Cc For the component of the actual value of the current of the filter capacitor in phase c, K ic Is the current feedback coefficient of the filter capacitor.
The virtual node voltage inner loop control module calculates a calculated value of the virtual node voltage according to an actual value of the grid-connected voltage and an actual value of the grid-connected current, and comprises the following steps:
calculating a calculated value of a virtual node voltage according to an actual value of a grid-connected voltage and an actual value of a grid-connected current in an abc three-phase static coordinate system;
and the calculated value of the virtual node voltage is transformed from the abc three-phase static coordinate system to the dq synchronous rotation coordinate system.
The calculated value of the virtual node voltage in the virtual node voltage inner loop control module is calculated by the following calculation formula:
wherein u is va For the component of the calculated value of the virtual node voltage in phase a, u vb For the component of the calculated value of the virtual node voltage in phase b, u vc For the component of the calculated value of the virtual node voltage in phase c, u ta Component of the actual value of the grid-connected voltage in phase a，u tb For the component of the actual value of the grid-connected voltage in phase b, u tc I is the component of the actual value of the grid-connected voltage in the c phase a I is the component of the actual value of the grid-connected current in phase a b I is the component of the actual value of the grid-connected current in phase b c For the component of the actual value of the grid-connected current in phase c, L v Is a virtual inductance value.
Example 3:
based on the same inventive concept, the invention also provides a computer device comprising a processor and a memory for storing a computer program comprising program instructions, the processor for executing the program instructions stored by the computer storage medium. The processor may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processor, digital signal processor (Digital Signal Processor, DSP), application specific integrated circuit (Application SpecificIntegrated Circuit, ASIC), off-the-shelf Programmable gate array (FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware components, etc., which are the computational core and control core of the terminal adapted to implement one or more instructions, in particular to load and execute one or more instructions in a computer storage medium to implement the corresponding method flow or corresponding functions, to implement the steps of the virtual node voltage feedback control method of an inverter in the above embodiments.
Example 4:
based on the same inventive concept, the present invention also provides a storage medium, in particular, a computer readable storage medium (Memory), which is a Memory device in a computer device, for storing programs and data. It is understood that the computer readable storage medium herein may include both built-in storage media in a computer device and extended storage media supported by the computer device. The computer-readable storage medium provides a storage space storing an operating system of the terminal. Also stored in the memory space are one or more instructions, which may be one or more computer programs (including program code), adapted to be loaded and executed by the processor. The computer readable storage medium herein may be a high-speed RAM memory or a non-volatile memory (non-volatile memory), such as at least one magnetic disk memory. One or more instructions stored in a computer-readable storage medium may be loaded and executed by a processor to implement the steps of a virtual node voltage feedback control method of an inverter in the above embodiments.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the foregoing embodiments are merely for illustrating the technical solution of the present invention and not for limiting the scope of protection thereof, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes, modifications or equivalents may be made to the specific embodiments of the application while the invention is read, and such changes, modifications or equivalents are within the scope of protection of the claims appended hereto.

Claims (14)

1. A virtual node voltage feedback control method of an inverter, comprising:
calculating a reference value of the virtual node voltage by using a current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current;
calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period;
calculating a pulse modulation voltage based on a modulation voltage value without a filter capacitor current feedback term and a current actual value of a filter capacitor;
modulating the pulse modulation voltage to obtain a pulse signal, and driving the bridge arm in the inverter to be disconnected by the pulse signal, thereby completing one cycle.
2. The method of claim 1, wherein the calculating a reference value for a virtual node voltage and the calculating a modulation voltage value without a filter capacitance current feedback term are both accomplished in a dq synchronous rotation coordinate system;
the calculation of the pulse modulation voltage is completed in an abc three-phase static coordinate system;
after the calculating of the modulation voltage value without the filter capacitor current feedback term and before the calculating of the pulse modulation voltage, the method further comprises:
and transforming the modulation voltage value without the filter capacitor current feedback item from the dq synchronous rotation coordinate system to the abc three-phase static coordinate system.
3. The method of claim 2, wherein the reference value of the virtual node voltage is calculated by the following calculation formula:
wherein u is vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H i For the current feedback coefficient, G i (s) is a current controller, i dref I is the component of the reference value of the grid-connected current in the d axis qref K being the component of the reference value of the grid-connected current on the q-axis dcp Decoupling coefficient i for dq synchronous rotation coordinate system d I is the component of the actual value of the grid-connected current in the d-axis q Is the component of the actual value of the grid-connected current on the q-axis.
4. The method of claim 2, wherein the modulated voltage value without the filter capacitor current feedback term is calculated by the following calculation formula:
wherein u is md1 For the component of the modulation voltage value in the d-axis without the filter capacitance current feedback term, u mq1 For the component of the modulation voltage value on the q-axis without the filter capacitor current feedback term, G u (s) is a voltage controller, u vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H u As the current feedback coefficient, u vd For the component of the calculated value of the virtual node voltage on the d-axis, u vq Is the component of the calculated value of the virtual node voltage on the q-axis.
5. The method of claim 2, wherein the pulse modulated voltage is calculated by the following calculation formula:
wherein u is ma For pulsing the component of the voltage in phase a, u mb U is the component of the pulse modulated voltage in phase b mc For pulsing the component of the voltage in phase c, u ma1 For the component of the modulation voltage value in phase a without the filter capacitor current feedback term, u mb1 For the component of the modulation voltage value in phase b without the filter capacitance current feedback term, u mc1 For the component of the modulating voltage value in phase c, i without the filter capacitor current feedback term Ca I is the component of the actual value of the current of the filter capacitor in the a phase Cb I is the component of the actual value of the current of the filter capacitor in phase b Cc For the component of the actual value of the current of the filter capacitor in phase c, K ic Is the current feedback coefficient of the filter capacitor.
6. The method of claim 2, wherein the calculating the virtual node voltage calculated from the actual value of the grid-connected voltage and the actual value of the grid-connected current comprises:
calculating a calculated value of the virtual node voltage according to the actual value of the grid-connected voltage and the actual value of the grid-connected current in the abc three-phase static coordinate system;
and transforming the calculated value of the virtual node voltage from the abc three-phase static coordinate system to the dq synchronous rotation coordinate system.
7. The method of claim 6, wherein the calculated value of the virtual node voltage is calculated by the following calculation formula:
wherein u is va For the component of the calculated value of the virtual node voltage in phase a, u vb For the component of the calculated value of the virtual node voltage in phase b, u vc For the component of the calculated value of the virtual node voltage in phase c, u ta For the component of the actual value of the grid-connected voltage in phase a, u tb For the component of the actual value of the grid-connected voltage in phase b, u tc I is the component of the actual value of the grid-connected voltage in the c phase a I is the component of the actual value of the grid-connected current in phase a b I is the component of the actual value of the grid-connected current in phase b c For the component of the actual value of the grid-connected current in phase c, L v Is a virtual inductance value.
8. A virtual node voltage feedback control system of an inverter, comprising:
the grid-connected current outer loop control module is used for calculating a reference value of the virtual node voltage by using the current controller based on the reference value of the grid-connected current of the inverter and the actual value of the grid-connected current;
the virtual node voltage inner loop control module is used for calculating a modulation voltage value without a filter capacitor current feedback item by using a voltage controller based on a reference value of the virtual node voltage and a calculated value of the virtual node voltage calculated according to an actual value of the grid-connected voltage and an actual value of the grid-connected current at the beginning of a period;
the capacitor current inner loop control module is used for calculating pulse modulation voltage based on the modulation voltage value without a filter capacitor current feedback item and the actual current value of the filter capacitor;
and the bridge arm pulse driving control module is used for modulating the pulse modulation voltage to obtain a pulse signal, and driving the bridge arm in the inverter to be disconnected by the pulse signal so as to complete one cycle.
9. The system of claim 8, wherein the grid-connected current outer loop control module calculating a reference value for a virtual node voltage and the virtual node voltage inner loop control module calculating a modulated voltage value without a filter capacitor current feedback term are both accomplished in a dq synchronous rotation coordinate system;
the capacitor current inner loop control module calculates the pulse modulation voltage to be completed in an abc three-phase static coordinate system;
after the virtual node voltage inner loop control module calculates the modulation voltage value without the filtering capacitor current feedback item and before the capacitor current inner loop control module calculates the pulse modulation voltage, the method further comprises the following steps:
and transforming the modulation voltage value without the filter capacitor current feedback item from the dq synchronous rotation coordinate system to the abc three-phase static coordinate system.
10. The system of claim 9, wherein the reference value for the virtual node voltage in the grid-connected current outer loop control module is calculated by the following calculation formula:
wherein u is vdref For the component of the reference value of the virtual node voltage on the d-axis, u vdref Is the component of the reference value of the virtual node voltage on the q axis, H i For the current feedback coefficient, G i (s) is a current controller, i dref I is the component of the reference value of the grid-connected current in the d axis qref K being the component of the reference value of the grid-connected current on the q-axis dcp Synchronous rotation coordinates for dqDecoupling coefficient of system i d I is the component of the actual value of the grid-connected current in the d-axis q Is the component of the actual value of the grid-connected current on the q-axis.
11. The system of claim 9, wherein the modulated voltage value in the virtual node voltage inner loop control module that does not contain a filter capacitor current feedback term is calculated by the following calculation formula:
wherein u is md1 For the component of the modulation voltage value in the d-axis without the filter capacitance current feedback term, u mq1 For the component of the modulation voltage value on the q-axis without the filter capacitor current feedback term, G u (s) is a voltage controller, u vdref For the component of the reference value of the virtual node voltage on the d-axis, u vqref Is the component of the reference value of the virtual node voltage on the q axis, H u As the current feedback coefficient, u vd For the component of the calculated value of the virtual node voltage on the d-axis, u vq Is the component of the calculated value of the virtual node voltage on the q-axis.
12. The system of claim 9, wherein the pulsed voltage in the capacitive current inner loop control module is calculated by the following calculation formula:
wherein u is ma For pulsing the component of the voltage in phase a, u mb U is the component of the pulse modulated voltage in phase b mc For pulsing the component of the voltage in phase c, u ma1 For the component of the modulation voltage value in phase a without the filter capacitor current feedback term, u mb1 For the component of the modulation voltage value in phase b without the filter capacitance current feedback term, u mc1 To be free of filtering electricityThe component of the modulating voltage value of the capacitive current feedback term in the c phase, i Ca I is the component of the actual value of the current of the filter capacitor in the a phase Cb I is the component of the actual value of the current of the filter capacitor in phase b Cc For the component of the actual value of the current of the filter capacitor in phase c, K ic Is the current feedback coefficient of the filter capacitor.
13. The system of claim 9, wherein the virtual node voltage inner loop control module calculates a calculated value of the virtual node voltage based on an actual value of the grid-tie voltage and an actual value of the grid-tie current, comprising:
calculating a calculated value of the virtual node voltage according to the actual value of the grid-connected voltage and the actual value of the grid-connected current in the abc three-phase static coordinate system;
and transforming the calculated value of the virtual node voltage from the abc three-phase static coordinate system to the dq synchronous rotation coordinate system.
14. The system of claim 13, wherein the calculated value of the virtual node voltage in the virtual node voltage inner loop control module is calculated by the following calculation formula:
wherein u is va For the component of the calculated value of the virtual node voltage in phase a, u vb For the component of the calculated value of the virtual node voltage in phase b, u vc For the component of the calculated value of the virtual node voltage in phase c, u ta For the component of the actual value of the grid-connected voltage in phase a, u tb For the component of the actual value of the grid-connected voltage in phase b, u tc I is the component of the actual value of the grid-connected voltage in the c phase a I is the component of the actual value of the grid-connected current in phase a b I is the component of the actual value of the grid-connected current in phase b c For the component of the actual value of the grid-connected current in phase c, L v Is a virtual inductance value.
CN202310862869.6A 2023-07-14 2023-07-14 Virtual node voltage feedback control method and system of inverter Pending CN117060498A (en)

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