CN113178893B - Inverter parallel soft start method and system based on virtual synchronous generator control - Google Patents
Inverter parallel soft start method and system based on virtual synchronous generator control Download PDFInfo
- Publication number
- CN113178893B CN113178893B CN202110578136.0A CN202110578136A CN113178893B CN 113178893 B CN113178893 B CN 113178893B CN 202110578136 A CN202110578136 A CN 202110578136A CN 113178893 B CN113178893 B CN 113178893B
- Authority
- CN
- China
- Prior art keywords
- frequency
- modulation wave
- inverter
- wave amplitude
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
-
- 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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
- Inverter Devices (AREA)
Abstract
The invention relates to an inverter parallel soft start method and system based on virtual synchronous generator control. The method comprises the following steps: enabling the first inverter to start in an idle load mode, and enabling the first inverter to output a first modulation wave amplitude value and a first frequency; performing phase locking on a second voltage and a second current of a port of a second inverter, starting the phase-locked second inverter in a current loop control mode based on constant-voltage constant-frequency control, and controlling the frequency and the phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter so that the second inverter outputs a second modulation wave amplitude value and a second frequency; generating a first modulation wave amplitude value after locking and a second modulation wave amplitude value after locking; and adjusting the amplitude and the frequency of the locked modulated wave to ensure that the amplitude of the two adjusted modulated waves is the same and the two adjusted frequencies are the same. The invention can realize the soft start of the parallel system under the condition that no circuit breaker exists between the port of the inverter and the alternating current bus.
Description
Technical Field
The invention relates to the field of inverter parallel soft start, in particular to an inverter parallel soft start method and system based on virtual synchronous generator control.
Background
In the isolated network system with two parallel machines, the inverter does not need to enter a public bus through the circuit breaker or the circuit breaker is in a normally closed state, and at the moment, the starting mode of the second equipment has some problems.
The starting process of the first starting mode is as follows:
after the first inverter is started, the second inverter detects the voltage at the port when being started, the measured voltage at the port and the phase angle obtained by phase locking are used as a voltage and frequency instruction, the second inverter is started in a constant voltage and constant frequency control mode, and then the voltage and frequency instruction of the inverter is converted into an instruction running under a virtual synchronous generator algorithm.
Such a starting method has problems in actual operation: the voltage U1 generated after the start-up of the first inverter is completed and the voltage U2 generated at the port of the second inverter, due to the line impedance, must have a voltage drop. The second inverter is started by taking U2 as an instruction, and because the voltage difference of the two inverter ports generates a circulating current, the system can be over-current, over-current protection is triggered, and the operation is stopped.
The second starting method has the following starting process:
and after the first inverter is started, the second inverter controls the voltage and current double closed-loop starting by the voltage frequency command obtained by the direct VSG algorithm. The problems at start-up of this method are: the frequency command calculated by the second inverter may be different from the frequency command value of the first inverter, that is, the frequency used when the voltage loop control performs coordinate transformation is different from the actual frequency of U2, and only when the rotation frequency of the rotating coordinate system is synchronized with the rotation frequency of the voltage-current vector, the voltage-current amount in the two-phase rotating coordinate system obtained through coordinate transformation can be subjected to PI control, but when the two frequencies are not synchronized, the voltage-current amount in the two-phase rotating coordinate system cannot be obtained through coordinate transformation, and therefore PI control cannot be performed.
Therefore, for the isolated network system with two parallel machines, the parallel system can not be started normally under the condition that no circuit breaker exists between the port of the inverter and the alternating current bus, and the parallel system can not be started when the electrical measurement values at the ports are inconsistent.
Disclosure of Invention
The invention aims to provide a parallel soft start method and a parallel soft start system of an inverter based on virtual synchronous generator control, which aim to solve the problem that a parallel system cannot be started under the condition that no circuit breaker exists between an inverter port and an alternating current bus and the starting problem caused by inconsistent electrical measurement quantity at each port so as to realize the starting of the parallel system.
In order to achieve the purpose, the invention provides the following scheme:
an inverter parallel soft start method based on virtual synchronous generator control comprises the following steps:
enabling a first inverter to start in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and enabling the first inverter to output a first modulation wave amplitude value and a first frequency required by the control of the virtual synchronous generator;
performing phase locking on a second voltage and a second current of a port of a second inverter, starting the phase-locked second inverter in a current loop control mode based on constant voltage and constant frequency control, and controlling the frequency and the phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter so that the second inverter outputs a second modulation wave amplitude value and a second frequency required by virtual synchronous generator control;
locking the first modulation wave amplitude and the second modulation wave amplitude to generate a locked first modulation wave amplitude and a locked second modulation wave amplitude;
and adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude and the locked second frequency to ensure that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
Optionally, the enabling the first inverter to start in an idle state and enabling the first inverter and the virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, so that the first inverter outputs a first modulation wave amplitude and a first frequency required by control of the virtual synchronous generator, specifically including:
enabling a first inverter to start in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and measuring a first voltage and a first current output by a port of the first inverter;
determining a first droop characteristic from the first voltage and the first current based on the virtual synchronous generator control algorithm; the first droop characteristic curve comprises a first curve representing a relation between active power and frequency and a second curve representing a relation between reactive power and voltage;
generating a voltage command and a frequency command required by the operation of the first inverter according to the first droop characteristic curve;
and performing voltage and current double closed-loop control according to the voltage command and the frequency command, so that the first inverter outputs a first modulation wave amplitude value and a first frequency required by virtual synchronous generator control.
Optionally, the phase-locking a second voltage and a second current at a port of the second inverter, starting the phase-locked second inverter in a current loop control manner based on constant-voltage and constant-frequency control, and controlling a frequency and a phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter, so that the second inverter outputs a second modulation wave amplitude and a second frequency required by the virtual synchronous generator control, and the method further includes:
determining a second droop characteristic from the second voltage and the second current based on the virtual synchronous generator control algorithm; the second droop characteristic includes a third curve representing an active power versus frequency and a fourth curve representing a reactive power versus voltage.
Optionally, the locking the first modulation wave amplitude and the second modulation wave amplitude to generate a locked first modulation wave amplitude and a locked second modulation wave amplitude specifically includes:
and according to a storage variable stored in a digital signal processor, locking a first modulation wave amplitude value generated by a voltage-current double closed loop control mode in the first inverter as a fixed value, locking a second modulation wave amplitude value generated by a current loop control mode in the second inverter as a fixed value, and generating a first modulation wave amplitude value after locking and a second modulation wave amplitude value after locking.
Optionally, the adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude, and the locked second frequency, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation, specifically includes:
and adjusting the locked first modulation wave amplitude and the locked first frequency according to the first curve and the second curve, and adjusting the locked second modulation wave amplitude and the locked second frequency according to the third curve and the fourth curve, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
An inverter parallel soft start system based on virtual synchronous generator control, comprising:
the first modulation wave amplitude and first frequency output module is used for enabling a first inverter to start in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and enabling the first inverter to output a first modulation wave amplitude and a first frequency required by the control of the virtual synchronous generator;
the second modulation wave amplitude and second frequency output module is used for performing phase locking on a second voltage and a second current of a port of a second inverter, starting the phase-locked second inverter in a current loop control mode based on constant-voltage constant-frequency control, and controlling the frequency and the phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter so that the second inverter outputs the second modulation wave amplitude and the second frequency required by the virtual synchronous generator control;
the locking module is used for locking the first modulation wave amplitude and the second modulation wave amplitude to generate a locked first modulation wave amplitude and a locked second modulation wave amplitude;
and the adjusting module is used for adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude and the locked second frequency, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
Optionally, the first modulation wave amplitude and first frequency output module specifically includes:
the first voltage and first current measuring unit is used for enabling a first inverter to start in a no-load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and measuring a first voltage and a first current output by a port of the first inverter;
a first droop characteristic determination unit for determining a first droop characteristic from the first voltage and the first current based on the virtual synchronous generator control algorithm; the first droop characteristic curve comprises a first curve representing a relationship between active power and frequency and a second curve representing a relationship between reactive power and voltage;
a voltage command and frequency command generating unit, configured to generate a voltage command and a frequency command required by the operation of the first inverter according to the first droop characteristic;
and the first modulation wave amplitude and first frequency output unit is used for performing voltage and current double closed-loop control according to the voltage command and the frequency command so that the first inverter outputs a first modulation wave amplitude and a first frequency required by virtual synchronous generator control.
Optionally, the method further includes:
a second droop characteristic determination module for determining a second droop characteristic from the second voltage and the second current based on the virtual synchronous generator control algorithm; the second droop characteristic includes a third curve representing an active power versus frequency and a fourth curve representing a reactive power versus voltage.
Optionally, the locking module specifically includes:
and the locking unit is used for locking a first modulation wave amplitude value generated by a voltage and current double closed-loop control mode in the first inverter as a fixed value and locking a second modulation wave amplitude value generated by a current loop control mode in the second inverter as a fixed value according to a storage variable stored in the digital signal processor, and generating a locked first modulation wave amplitude value and a locked second modulation wave amplitude value.
Optionally, the adjusting module specifically includes:
and the adjusting unit is used for adjusting the locked first modulation wave amplitude and the locked first frequency according to the first curve and the second curve, and adjusting the locked second modulation wave amplitude and the locked second frequency according to the third curve and the fourth curve, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the invention provides an inverter parallel soft start method and system based on virtual synchronous generator control, which are characterized in that a first inverter outputs a first modulation wave amplitude value and a first frequency based on a virtual synchronous generator control algorithm; phase locking is carried out on a second voltage and a second current of a port of a second inverter, so that the second inverter outputs a second modulation wave amplitude value and a second frequency required by virtual synchronous generator control; and adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude and the second frequency to ensure that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude and the adjusted first frequency is the same as the adjusted second frequency modulation frequency, so that the electrical measurement quantities at the ports of the first inverter and the second inverter are the same to ensure the normal operation of the equipment and realize the soft start of the parallel system under the condition that no circuit breaker exists between the port of the inverter and the alternating current bus.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flowchart of a parallel soft start method for an inverter based on virtual synchronous generator control according to the present invention;
FIG. 2 is a structural diagram of an inverter parallel soft start system based on virtual synchronous generator control according to the present invention;
FIG. 3 is a block diagram of active frequency control of a virtual synchronous machine;
FIG. 4 is a schematic diagram of a first curve or a third curve;
FIG. 5 is a block diagram of virtual synchronous machine reactive voltage control;
FIG. 6 is a schematic diagram of a second curve or a fourth curve;
FIG. 7 is a virtual synchronizer control block diagram;
FIG. 8 is a schematic diagram of an inverter parallel system;
fig. 9 is a schematic diagram of an active power distribution process in which two inverters are operated in parallel;
FIG. 10 is a schematic diagram of a reactive power distribution process in which two inverters are operated in parallel;
FIG. 11 is a flow chart of parallel soft start operation;
FIG. 12 is a schematic diagram of the three-phase voltage per unit value, frequency and load conditions in the simulation process;
fig. 13 is a schematic diagram of modulation waves of the first inverter and the second inverter in the rotating coordinate system.
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 order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a flowchart of a method for soft starting an inverter in parallel based on virtual synchronous generator control according to the present invention, and as shown in fig. 1, a method for soft starting an inverter in parallel based on virtual synchronous generator control includes:
step 101: the method comprises the steps of starting a first inverter in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and enabling the first inverter to output a first modulation wave amplitude value and a first frequency required by the control of the virtual synchronous generator.
The step 101 specifically includes: enabling a first inverter to start in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and measuring a first voltage and a first current output by a port of the first inverter; determining a first droop characteristic from the first voltage and the first current based on the virtual synchronous generator control algorithm; the first droop characteristic curve comprises a first curve representing a relationship between active power and frequency and a second curve representing a relationship between reactive power and voltage; generating a voltage command and a frequency command required by the operation of the first inverter according to the first droop characteristic curve; and performing voltage and current double closed-loop control according to the voltage command and the frequency command, so that the first inverter outputs a first modulation wave amplitude value and a first frequency required by virtual synchronous generator control.
In practical application, a first inverter is connected with a DSP (digital signal processor), no-load starting is carried out, the inverter and a synchronous generator have the same external characteristics through a virtual synchronous generator control algorithm, the virtual synchronous generator control algorithm obtains a voltage instruction and a frequency instruction required by the operation of the inverter according to the characteristics of a droop curve in the virtual synchronous generator control algorithm by measuring active power and reactive power output by an inverter port, and voltage and current double closed-loop control is carried out by using the obtained voltage instruction and frequency instruction, so that the inverter outputs the voltage amplitude and the frequency required by the control of the virtual synchronous generator. Here, the droop curve characteristics in the virtual synchronous generator control algorithm are first droop curve characteristics including a first curve (P-f droop curve) representing the relationship between active power and frequency and a second curve (Q-U droop curve) representing the relationship between reactive power and voltage.
Step 102: and phase locking is carried out on a second voltage and a second current of a port of the second inverter, the second inverter after phase locking is started in a current loop control mode based on constant voltage and constant frequency control, and the frequency and the phase angle of the second current are controlled to be the frequency and the phase angle of the second inverter after phase locking, so that the second inverter outputs a second modulation wave amplitude value and a second frequency required by virtual synchronous generator control.
The step 102 further includes: determining a second droop characteristic from the second voltage and the second current based on the virtual synchronous generator control algorithm; the second droop characteristic includes a third curve representing an active power versus frequency relationship and a fourth curve representing a reactive power versus voltage relationship.
In practical application, the second inverter is connected with the DSP, phase locking is carried out on the voltage and current quantity at the port, operation and starting are carried out in a current loop control mode, the frequency and the phase angle of output current of the inverter are controlled to be the frequency and the phase angle obtained through phase locking, the amplitude and the frequency of a modulation wave at the moment are obtained, a second droop characteristic curve is obtained according to a virtual synchronous generator algorithm, and the second droop characteristic curve comprises a third curve (P-f droop curve) representing the relation between active power and frequency and a fourth curve (Q-U droop curve) representing the relation between reactive power and voltage.
Step 103: and locking the first modulation wave amplitude and the second modulation wave amplitude to generate a locked first modulation wave amplitude and a locked second modulation wave amplitude.
The step 103 specifically includes: and according to a storage variable stored in a digital signal processor, locking a first modulation wave amplitude value generated by a voltage-current double closed loop control mode in the first inverter as a fixed value, locking a second modulation wave amplitude value generated by a current loop control mode in the second inverter as a fixed value, and generating a first modulation wave amplitude value after locking and a second modulation wave amplitude value after locking.
In practical application, two storage variables are defined in a DSP program and are assigned as a modulation wave and a frequency value of a first inverter, so that a first modulation wave amplitude value generated by double closed-loop control in the first inverter is locked as a fixed value and is not influenced by the double closed-loop control; and defining another two storage variables in the DSP program, assigning the other two storage variables as the amplitude value and the frequency value of the modulation wave of the second inverter, and locking the amplitude value of the second modulation wave generated by the current loop control of the second inverter into a fixed value so as to ensure that the second modulation wave is not influenced by the current loop control. At this time, the fixed values of the two inverters are the amplitude and the frequency of the modulation wave in the no-load state.
Step 104: and adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude and the locked second frequency to ensure that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
The step 104 specifically includes: and adjusting the amplitude and the frequency of the locked first modulation wave according to the first curve and the second curve, and adjusting the amplitude and the frequency of the locked second modulation wave according to the third curve and the fourth curve, so that the amplitude of the adjusted first modulation wave is the same as the amplitude of the adjusted second modulation wave, and the frequency of the adjusted first modulation wave is the same as the frequency of the adjusted second modulation wave.
In practical application, the two inverters measure active power in real time, and modify the frequency of a modulation wave according to the one-to-one correspondence relationship between the active power and the frequency in a corresponding P-f droop curve on the basis of the modulation wave frequency in an idle state; on the basis of the amplitude of the modulation wave in the no-load state, the reactive power is measured, and the amplitude of the modulation wave is modified according to the one-to-one correspondence relationship between the reactive power and the voltage in the corresponding Q-U droop curve, so that the frequency instructions and the amplitude of the modulation wave of the two inverters are finally the same, and the normal operation of equipment is guaranteed.
Fig. 2 is a structural diagram of an inverter parallel soft start system based on virtual synchronous generator control, and the inverter parallel soft start system based on virtual synchronous generator control includes:
the first modulation wave amplitude and first frequency output module 201 is configured to enable a first inverter to start in an idle load mode, and enable the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, so that the first inverter outputs a first modulation wave amplitude and a first frequency required by virtual synchronous generator control.
The first modulation wave amplitude and first frequency output module 201 specifically includes: the first voltage and first current measuring unit is used for enabling a first inverter to start in a no-load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and measuring a first voltage and a first current output by a port of the first inverter; a first droop characteristic determination unit for determining a first droop characteristic from the first voltage and the first current based on the virtual synchronous generator control algorithm; the first droop characteristic curve comprises a first curve representing a relation between active power and frequency and a second curve representing a relation between reactive power and voltage; a voltage command and frequency command generating unit, configured to generate a voltage command and a frequency command required by the operation of the first inverter according to the first droop characteristic curve; and the first modulation wave amplitude and frequency output unit is used for performing voltage and current double closed-loop control according to the voltage command and the frequency command so that the first inverter outputs a first modulation wave amplitude and a first frequency required by virtual synchronous generator control.
The second modulation wave amplitude and second frequency output module 202 is configured to phase-lock a second voltage and a second current at a port of the second inverter, start the phase-locked second inverter in a current loop control manner based on constant-voltage and constant-frequency control, and control the frequency and the phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter, so that the second inverter outputs a second modulation wave amplitude and a second frequency required by the virtual synchronous generator.
The invention also includes: a second droop characteristic determination module for determining a second droop characteristic from the second voltage and the second current based on the virtual synchronous generator control algorithm; the second droop characteristic includes a third curve representing an active power versus frequency relationship and a fourth curve representing a reactive power versus voltage relationship.
The locking module 203 is configured to lock the first modulation wave amplitude and the second modulation wave amplitude, and generate a locked first modulation wave amplitude and a locked second modulation wave amplitude.
The locking module 203 specifically includes: and the locking unit is used for locking a first modulation wave amplitude value generated by a voltage and current double closed loop control mode in the first inverter as a fixed value and locking a second modulation wave amplitude value generated by a current loop control mode in the second inverter as a fixed value according to a storage variable stored in the digital signal processor, and generating a first modulation wave amplitude value after locking and a second modulation wave amplitude value after locking.
The adjusting module 204 is configured to adjust the locked first modulation wave amplitude, the first frequency, the locked second modulation wave amplitude, and the second frequency, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
The adjusting module 204 specifically includes: and the adjusting unit is used for adjusting the locked first modulation wave amplitude and the locked first frequency according to the first curve and the second curve, and adjusting the locked second modulation wave amplitude and the locked second frequency according to the third curve and the fourth curve, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
FIG. 3 is a block diagram of active frequency control of a virtual synchronous machine, where ω is N At a rated angular velocity, ω L As actual angular velocity, k ω For active frequency droop systemNumber, P N For rated active power, P OUT Is the output active power, Δ P is P N And P OUT Delta T is the difference between the actual torque and the rated torque, D is the damping coefficient, js is the rotational inertia of the synchronous generator, and delta omega is omega L And omega N Difference of (c), ω ref The first half of the angular velocity instruction value is used for obtaining virtual mechanical power according to the droop characteristic of the active frequency of the synchronous motor and obtaining the variation of the angular velocity by making a difference with the output electromagnetic power, and finally the angular velocity instruction value is obtained through a rotor motion equation part in the damping and inertia link process.
Fig. 4 is a schematic diagram of a first or third curve, wherein the abscissa represents active power and the ordinate represents angular velocity, and a quantitative relationship exists between the frequency f and the angular velocity ω of the synchronous generator, ω =2 π f. Omega N At nominal angular velocity, ω L Is the actual angular velocity, P N At rated power, P L Is the actual power. The active power and the frequency of the output of the synchronous generator in the primary frequency modulation process of the synchronous generator are reflected as droop characteristics.
FIG. 5 is a block diagram of virtual synchronous machine reactive voltage control, wherein Q N Rated reactive power, Q L To real reactive power, k u Is a reactive voltage droop coefficient, k p ，k i S is a parameter of the PI regulator, i f Is the excitation current. Comparing the sampling measurement of the reactive power with a rated value thereof to obtain a difference, multiplying the difference by a corresponding coefficient to obtain a voltage difference corresponding to the reactive power variation, superposing the voltage difference with a given value of the system voltage to obtain a reference value of voltage closed-loop regulation, comparing the feedback voltage with the obtained reference value to obtain a difference, and regulating by a PI regulator to obtain a virtual exciting current.
FIG. 6 is a schematic diagram of a second or fourth curve, wherein the abscissa represents reactive power and the ordinate represents voltage, Q N Rated reactive power, Q 1 For actual reactive power, U N For rated voltage, U 1 Is the actual voltage. The reactive voltage regulation process of the synchronous generator is reflected in the characteristic of reactive voltage droop in external characteristics.
FIG. 7 is a control block diagram of a virtual synchronous machine, wherein G1 to G6 are bridge arm numbers of IGBT, respectively, C 1 Is a DC-side voltage-stabilizing capacitor, i a 、i b 、i c The current value output by the bridge arm port of the inverter, C is the filter capacitor on the alternating current side, e a 、e b 、e c For the value of the voltage, u, output by the inverter legs a 、u b 、u c Is the value of the voltage, P, output by the port e 、Q e For the power value output by the inverter, ω is the frequency measurement obtained by phase locking, E ref 、ω ref The command values are voltage and frequency.
Obtaining the power P output by the inverter by measuring the voltage and current values output by the bridge arm port of the inverter e 、Q e Obtaining the amplitude E of the port voltage instruction value through the active frequency droop characteristic and the reactive voltage droop characteristic of the virtual synchronous generator ref And the frequency command value omega ref . And obtaining a required modulation wave signal through voltage and current double closed-loop control, and generating a required PWM signal through PWM modulation.
FIG. 8 is a schematic diagram of a parallel inverter system in which
Current, U, respectively output from the terminals of the two inverters 1 、U 2 Respectively the voltages output by the terminals of the two inverters,
respectively, the phase angle, P, of the terminal voltage of two inverters relative to the voltage of a common load point 1 、P 2 、Q 1 、Q 2 Respectively the active power and the reactive power output by the ends of the two inverters. Z is a linear or branched member 1 、Z 2 Line impedances θ of two inverters to a common load, respectively 1 Is the impedance angle, θ, of the first inverter line 2 Is the impedance angle, U, of the second inverter line pcc To the terminal voltage of the load, R 1 、X 1 Resistance and reactance, R, respectively, of the connection line to the first inverter 2 、X 2 Resistance and reactance, i, respectively, of the connection line to the second inverter 0 For the current flowing through the load, Z L Is the reactance of the load.
Fig. 9 is a schematic diagram of an active power distribution process in which two inverters operate in parallel, and an example is taken that two inverters with the same droop curve are connected in parallel. Supposing that at a certain moment, the machine No. 1 (namely, a first inverter) works at the point A, the machine No. 2 (namely, a second inverter) works at the point B, and at the moment, the output frequency of the machine No. 2 is greater than that of the machine No. 1, so that the phase angle of a leading bus of the machine No. 2 is gradually increased, the output power of the machine No. 2 is also gradually increased according to the output characteristic of active power, and the working point of the machine No. 2 moves downwards along a curve; the frequency of the machine No. 1 is small, the phase angle is lagged, the output power of the machine No. 1 is gradually reduced by the output characteristic of active power, the working point of the machine No. 1 moves upwards along the droop curve until the frequencies of the two inverters are equal, and the system reaches a stable state and the active power is equally divided.
Fig. 10 is a schematic diagram of a reactive power distribution process of parallel operation of two inverters, assuming that at a certain time, the machine 1 works at point C, and the machine 2 works at point D, at which time the voltage of the machine 2 is greater than that of the machine 1, which makes the difference between the terminal voltage of the machine 2 and the load voltage larger, and it can be known from the reactive power output characteristics that the reactive power output by the machine 2 is also gradually increased, the working point of the machine 2 moves down along the curve, and the working point of the machine 1 moves up along the droop curve until the voltages of the two inverters are equal, so that the system reaches a steady state and the reactive power is equally distributed.
Fig. 11 is a flow chart of parallel soft start operation, in which first, a first energy storage inverter finishes no-load start, operates according to voltage and frequency commands obtained by a virtual synchronous generator algorithm, obtains amplitude and frequency of a modulation wave through constant voltage and constant frequency control according to the voltage and frequency commands, and obtains a P-f droop curve and a Q-U droop curve according to a virtual synchronous generator control strategy; the second energy storage inverter is used for phase locking of the voltage and current quantity at the port, the current loop is operated and started based on constant voltage and constant frequency control to obtain the amplitude and frequency of a modulation wave, and a P-f droop curve and a Q-U droop curve are obtained according to a virtual synchronous generator control strategy; locking the amplitude of a modulation wave generated by double closed-loop control in first equipment, and locking the amplitude of a modulation wave generated by current loop control in second equipment; and the two devices respectively modify respective frequency instructions according to the P-f droop curves and respectively modify respective modulation wave amplitudes according to the Q-U droop curves, so that the frequency instructions and the modulation wave amplitudes of the two inverters are identical to ensure the normal operation of the devices.
The inverter parallel soft start method or system based on virtual synchronous generator control can solve the parallel system start problem under the condition that no circuit breaker exists between the inverter port and the alternating current bus, can avoid the start problem caused by inconsistent electrical measurement quantity at each port, and realizes the start of the parallel system.
The starting conditions are as follows:
the simulation experiment is carried out on the inverter parallel soft start method based on the virtual synchronous generator control under the working conditions that the droop coefficients are the same and the line impedance is the same. And initially, the two-machine starting device is in an idle load state, 10kW active load and 1kvar reactive load are put into the two-machine starting device 4s later after the two-machine starting device is started, and the active and reactive loads are continuously increased 6s later. The three-phase voltage per unit value, the frequency and the load condition in the simulation process are shown in fig. 12, the modulation waves of the two machines in the rotating coordinate system are shown in fig. 13, and the simulation result shows that the method has feasibility, wherein Md1 is a d axis, and Mq1 is a q axis.
In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principle and the embodiment of the present invention are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. An inverter parallel soft start method based on virtual synchronous generator control is characterized by comprising the following steps:
enabling a first inverter to start in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and enabling the first inverter to output a first modulation wave amplitude value and a first frequency required by control of the virtual synchronous generator;
performing phase locking on a second voltage and a second current of a port of a second inverter, starting the phase-locked second inverter in a current loop control mode based on constant voltage and constant frequency control, and controlling the frequency and the phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter so that the second inverter outputs a second modulation wave amplitude value and a second frequency required by virtual synchronous generator control;
locking the first modulation wave amplitude and the second modulation wave amplitude to generate a locked first modulation wave amplitude and a locked second modulation wave amplitude;
adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude and the locked second frequency to enable the adjusted first modulation wave amplitude to be the same as the adjusted second modulation wave amplitude and the adjusted first frequency to be the same as the adjusted second frequency modulation rate; the two inverters measure active power in real time, and modify the frequency of the modulation wave according to the one-to-one correspondence relationship between the active power and the frequency in the corresponding P-f droop curve on the basis of the modulation wave frequency in the no-load state; on the basis of the amplitude of the modulation wave in the no-load state, the reactive power is measured, and the amplitude of the modulation wave is modified according to the one-to-one correspondence relationship between the reactive power and the voltage in the corresponding Q-U droop curve, so that the frequency instructions and the amplitude of the modulation wave of the two inverters are finally the same, and the normal operation of equipment is guaranteed.
2. The inverter parallel soft-start method based on virtual synchronous generator control according to claim 1, wherein the enabling a first inverter to start in a no-load mode and enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, so that the first inverter outputs a first modulation wave amplitude and a first frequency required by virtual synchronous generator control, specifically comprises:
the method comprises the steps that a first inverter is started in a no-load mode, the first inverter and a virtual synchronous generator have the same external characteristics through a virtual synchronous generator control algorithm, and a first voltage and a first current output by a port of the first inverter are measured;
determining a first droop characteristic from the first voltage and the first current based on the virtual synchronous generator control algorithm; the first droop characteristic curve comprises a first curve representing a relationship between active power and frequency and a second curve representing a relationship between reactive power and voltage;
generating a voltage command and a frequency command required by the operation of the first inverter according to the first droop characteristic curve;
and performing voltage and current double closed-loop control according to the voltage command and the frequency command, so that the first inverter outputs a first modulation wave amplitude value and a first frequency required by virtual synchronous generator control.
3. The inverter parallel soft start method based on virtual synchronous generator control according to claim 2, wherein the phase-locking a second voltage and a second current of a port of a second inverter, starting the phase-locked second inverter in a current loop control manner based on constant voltage and constant frequency control, and controlling a frequency and a phase angle of the second current to a frequency and a phase angle of the phase-locked second inverter so that the second inverter outputs a second modulation wave amplitude and a second frequency required by virtual synchronous generator control, and thereafter further comprising:
determining a second droop characteristic from the second voltage and the second current based on the virtual synchronous generator control algorithm; the second droop characteristic includes a third curve representing an active power versus frequency and a fourth curve representing a reactive power versus voltage.
4. The inverter parallel soft-start method based on virtual synchronous generator control according to claim 3, wherein the locking the first modulation wave amplitude and the second modulation wave amplitude to generate a locked first modulation wave amplitude and a locked second modulation wave amplitude specifically comprises:
and according to a storage variable stored in a digital signal processor, locking a first modulation wave amplitude value generated by a voltage-current double closed loop control mode in the first inverter as a fixed value, locking a second modulation wave amplitude value generated by a current loop control mode in the second inverter as a fixed value, and generating a first modulation wave amplitude value after locking and a second modulation wave amplitude value after locking.
5. The inverter parallel soft-start method based on virtual synchronous generator control according to claim 4, wherein the adjusting the locked first modulation wave amplitude, the first frequency, the locked second modulation wave amplitude, and the second frequency such that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate specifically comprises:
and adjusting the locked first modulation wave amplitude and the locked first frequency according to the first curve and the second curve, and adjusting the locked second modulation wave amplitude and the locked second frequency according to the third curve and the fourth curve, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate.
6. An inverter parallel soft start system based on virtual synchronous generator control, comprising:
the first modulation wave amplitude and first frequency output module is used for enabling a first inverter to start in an idle load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and enabling the first inverter to output a first modulation wave amplitude and a first frequency required by the control of the virtual synchronous generator;
a second modulation wave amplitude and second frequency output module, configured to phase-lock a second voltage and a second current at a port of a second inverter, start the phase-locked second inverter in a current loop control manner based on constant-voltage and constant-frequency control, and control a frequency and a phase angle of the second current to be the frequency and the phase angle of the phase-locked second inverter, so that the second inverter outputs a second modulation wave amplitude and a second frequency required by the virtual synchronous generator control;
the locking module is used for locking the first modulation wave amplitude and the second modulation wave amplitude and generating a locked first modulation wave amplitude and a locked second modulation wave amplitude;
the adjusting module is used for adjusting the locked first modulation wave amplitude, the locked first frequency, the locked second modulation wave amplitude and the locked second frequency, so that the adjusted first modulation wave amplitude is the same as the adjusted second modulation wave amplitude, and the adjusted first frequency is the same as the adjusted second frequency modulation rate; the two inverters measure active power in real time, and modify the frequency of the modulation wave according to the one-to-one correspondence relationship between the active power and the frequency in the corresponding P-f droop curve on the basis of the modulation wave frequency in the no-load state; on the basis of the amplitude of the modulation wave in the no-load state, the reactive power is measured, and the amplitude of the modulation wave is modified according to the one-to-one correspondence relationship between the reactive power and the voltage in the corresponding Q-U droop curve, so that the frequency instructions and the amplitude of the modulation wave of the two inverters are finally identical, and the normal operation of equipment is ensured.
7. The inverter parallel soft start system based on virtual synchronous generator control according to claim 6, wherein the first modulation wave amplitude and first frequency output module specifically comprises:
the first voltage and first current measuring unit is used for enabling a first inverter to start in a no-load mode, enabling the first inverter and a virtual synchronous generator to have the same external characteristics through a virtual synchronous generator control algorithm, and measuring a first voltage and a first current output by a port of the first inverter;
a first droop characteristic determination unit for determining a first droop characteristic from the first voltage and the first current based on the virtual synchronous generator control algorithm; the first droop characteristic curve comprises a first curve representing a relationship between active power and frequency and a second curve representing a relationship between reactive power and voltage;
a voltage command and frequency command generating unit, configured to generate a voltage command and a frequency command required by the operation of the first inverter according to the first droop characteristic curve;
and the first modulation wave amplitude and first frequency output unit is used for performing voltage and current double closed-loop control according to the voltage command and the frequency command so that the first inverter outputs a first modulation wave amplitude and a first frequency required by virtual synchronous generator control.
8. The virtual synchronous generator control-based inverter parallel soft start system according to claim 7, further comprising:
a second droop characteristic determination module for determining a second droop characteristic from the second voltage and the second current based on the virtual synchronous generator control algorithm; the second droop characteristic includes a third curve representing an active power versus frequency and a fourth curve representing a reactive power versus voltage.
9. The virtual synchronous generator control-based inverter parallel soft start system according to claim 8, wherein the locking module specifically comprises:
and the locking unit is used for locking a first modulation wave amplitude value generated by a voltage and current double closed-loop control mode in the first inverter as a fixed value and locking a second modulation wave amplitude value generated by a current loop control mode in the second inverter as a fixed value according to a storage variable stored in the digital signal processor, and generating a locked first modulation wave amplitude value and a locked second modulation wave amplitude value.
10. The inverter parallel soft-start system based on virtual synchronous generator control according to claim 9, wherein the adjusting module specifically includes:
and the adjusting unit is used for adjusting the amplitude and the frequency of the locked first modulation wave according to the first curve and the second curve, and adjusting the amplitude and the frequency of the locked second modulation wave according to the third curve and the fourth curve, so that the amplitude of the adjusted first modulation wave is the same as the amplitude of the adjusted second modulation wave, and the frequency of the adjusted first modulation wave is the same as the frequency of the adjusted second modulation wave.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110578136.0A CN113178893B (en) | 2021-05-26 | 2021-05-26 | Inverter parallel soft start method and system based on virtual synchronous generator control |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110578136.0A CN113178893B (en) | 2021-05-26 | 2021-05-26 | Inverter parallel soft start method and system based on virtual synchronous generator control |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113178893A CN113178893A (en) | 2021-07-27 |
| CN113178893B true CN113178893B (en) | 2022-11-29 |
Family
ID=76927044
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110578136.0A Active CN113178893B (en) | 2021-05-26 | 2021-05-26 | Inverter parallel soft start method and system based on virtual synchronous generator control |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113178893B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102157956A (en) * | 2011-03-01 | 2011-08-17 | 国网电力科学研究院 | Virtual-impedance-based inverter parallel running method |
| CN106130061A (en) * | 2016-06-12 | 2016-11-16 | 上海追日电气有限公司 | The soft start of a kind of energy storage inverter in parallel runs system and method |
| CN110707742A (en) * | 2019-09-10 | 2020-01-17 | 西安许继电力电子技术有限公司 | Multi-converter parallel off-grid starting control system and starting method |
| CN111355268A (en) * | 2018-12-24 | 2020-06-30 | 许继集团有限公司 | Grid-connected starting control method and system of virtual synchronous generator |
| CN111799836A (en) * | 2020-05-22 | 2020-10-20 | 国网浙江平阳县供电有限责任公司 | Modular energy storage converter parallel operation and hot plug control method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105634309B (en) * | 2014-11-06 | 2018-06-22 | 台达电子工业股份有限公司 | A kind of control method and control device for inversion system |
-
2021
- 2021-05-26 CN CN202110578136.0A patent/CN113178893B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102157956A (en) * | 2011-03-01 | 2011-08-17 | 国网电力科学研究院 | Virtual-impedance-based inverter parallel running method |
| CN106130061A (en) * | 2016-06-12 | 2016-11-16 | 上海追日电气有限公司 | The soft start of a kind of energy storage inverter in parallel runs system and method |
| CN111355268A (en) * | 2018-12-24 | 2020-06-30 | 许继集团有限公司 | Grid-connected starting control method and system of virtual synchronous generator |
| CN110707742A (en) * | 2019-09-10 | 2020-01-17 | 西安许继电力电子技术有限公司 | Multi-converter parallel off-grid starting control system and starting method |
| CN111799836A (en) * | 2020-05-22 | 2020-10-20 | 国网浙江平阳县供电有限责任公司 | Modular energy storage converter parallel operation and hot plug control method |
Non-Patent Citations (1)
| Title |
|---|
| 微电网孤岛运行下的频率控制研究;缪勇等;《电器与能效管理技术》;20150130(第02期);第49-55、64页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113178893A (en) | 2021-07-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11043817B2 (en) | Method for feeding electrical power into an electrical power supply network | |
| US4982147A (en) | Power factor motor control system | |
| Zhi et al. | Direct power control of DFIG with constant switching frequency and improved transient performance | |
| US7683568B2 (en) | Motor drive using flux adjustment to control power factor | |
| Adzic et al. | Maximum power search in wind turbine based on fuzzy logic control | |
| CN111431208B (en) | Voltage source and current source dual-mode self-adaptive coordination control method for wind turbine generator | |
| Pattnaik et al. | Adaptive speed observer for a stand-alone doubly fed induction generator feeding nonlinear and unbalanced loads | |
| CN106877710B (en) | Three-phase PWM rectifier multi-loop control circuit and control method based on virtual synchronous motor | |
| CN111277001A (en) | Fan grid-connected control method based on virtual synchronous generator parameter adaptive control | |
| CN108429289B (en) | Control method and system based on virtual synchronous generator | |
| Shukla et al. | A novel voltage and frequency controller for standalone DFIG based Wind Energy Conversion System | |
| CN112260330A (en) | Virtual synchronous machine control method for hybrid micro-grid MMC interconnection converter | |
| US7187155B2 (en) | Leakage inductance saturation compensation for a slip control technique of a motor drive | |
| CN110994680B (en) | Photovoltaic virtual synchronous machine stability control method with self-adaptive inertia coefficient | |
| CN109980682A (en) | VSG energy-accumulating power station active frequency support and control method based on power feedforward | |
| CN111525595A (en) | Virtual synchronous control system of power distribution network flexible switch device | |
| CN109617082A (en) | A kind of Transient Stability Control method inhibiting micro-capacitance sensor voltage frequency out-of-limit | |
| Li et al. | Developing a machine equivalent inertial response for a virtual oscillator controlled inverter in a machine-inverter based microgrid | |
| Kendouli et al. | High performance PWM converter control based PMSG for variable speed wind turbine | |
| Narula et al. | Tuning and evaluation of grid-forming converters for grid-support | |
| CN116632866B (en) | Hybrid energy storage self-adaptive inertia VSG control method for liquid flow super-capacity lithium battery | |
| CN109193609A (en) | A kind of DC grid DC voltage control method for coordinating based on VSG control | |
| CN116683491A (en) | Inertia control method for new energy micro-grid | |
| CN113178893B (en) | Inverter parallel soft start method and system based on virtual synchronous generator control | |
| CN117134406A (en) | Virtual synchronous machine-based control method and system for network-structured flexible direct current system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |