CN116231724B - Virtual inertia self-adaptive adjusting method of grid-structured inverter - Google Patents
Virtual inertia self-adaptive adjusting method of grid-structured inverter Download PDFInfo
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Classifications
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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
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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
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0006—Arrangements for supplying an adequate voltage to the control circuit of converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
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Abstract
Compared with the traditional voltage proportional integral control, the virtual inertia self-adaptive regulation method of the grid-structured inverter can effectively improve the problem of the output power quality when the inverter is connected with a local nonlinear load by using a multiple resonance controller in a voltage control loop; the self-adaptive virtual inertia which can be changed according to frequency fluctuation is constructed by utilizing a self-adaptive control principle and utilizing a Sigmoid function, so that the potential of improving the frequency stability is effectively stimulated, the unstable occurrence of a system is prevented, and the dynamic response of the system is improved.
Description
Technical Field
The invention belongs to the technical field of control of a grid-built inverter, and particularly relates to a virtual inertia self-adaptive adjusting method of the grid-built inverter.
Background
The large scale popularity of renewable and other distributed energy sources presents significant challenges to the power industry. However, large-scale access of new energy is accompanied by withdrawal of a corresponding synchronous generator and increase of a power supply based on an inverter, so that inertia of the system is greatly reduced, and frequency stability becomes a problem. Thus, a mesh-type inverter has been developed.
In the control of the existing grid-type inverter, the problems that the fluctuation of power input, the frequency oscillation, the output response speed and the oscillation of the grid-type inverter cannot be simultaneously met due to unknown system dynamics and difficult optimization of virtual inertia and damping parameters are common.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a virtual inertia self-adaptive adjusting method of a grid-built inverter, which solves the problems that the power input fluctuation, frequency oscillation, output response speed and oscillation of the grid-built inverter cannot be met simultaneously due to unknown system dynamics and difficult optimization of virtual inertia and damping parameters in the prior art.
The invention adopts the following technical scheme.
A virtual inertia self-adaptive adjusting method of a grid-structured inverter comprises the following steps:
step 1: performing control by using an inner ring voltage multiple resonance controller;
step 2: executing control by using the virtual inertia power outer loop controller;
step 3: the virtual inertia is adjusted by using the virtual inertia adaptive adjuster.
Preferably, the method for performing control by using the inner loop voltage multiple resonance controller includes:
the inner ring voltage multiple resonance controller firstly converts the output voltage, the output current and the bridge arm current of the grid-formed inverter into a synchronous rotation dq coordinate system, inputs reference voltage and actual output voltage in voltage ring control, and then outputs a reference value of the bridge arm current under the action of the multiple resonance controller; and then, entering current loop control, controlling a reference value and an actual value of bridge arm current through proportional integral to output a dq axis component of bridge arm voltage, generating a driving signal of a 6-way switching device of the grid-built inverter through a modulation module after inverse transformation, and driving the voltage type three-phase bridge inverter to output a required three-phase voltage current waveform.
Preferably, the reference voltage and the actual output voltage are input in the voltage loop control, and then the reference value of the bridge arm current is output under the action of the multiple resonance controller; then, entering current loop control, and controlling the reference value and the actual value of the bridge arm current through proportional integral to output the dq axis component of the bridge arm voltage, wherein the method comprises the following steps:
in the voltage loop control, a reference voltage and an output voltage of a grid-formed inverter as an actual output voltage are input, a d-axis component of the output voltage of the grid-formed inverter tracks a d-axis component reference value through a multiple resonance controller, and the output value of the multiple resonance controller superimposes a d-axis component of an output current and a q-axis compensation component-omega C of a feedforward output voltage f U oq As a reference value for the d-axis component of the bridge arm current; the bridge arm current tracks the d-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the d-axis component of the output voltage and the q-axis compensation component-omega L of the feedforward bridge arm current f I rq As d-axis component of bridge arm voltage;
the q-axis component of the output voltage of the grid-formed inverter tracks the q-axis component reference value by a multiple resonance controller whose output value superimposes the q-axis component of the output current and the d-axis compensation component- ωC of the feedforward output voltage f U od As a reference value for the q-axis component of the bridge arm current; the bridge arm current tracks the q-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the q-axis component of the output voltage and the d-axis compensation component-omega L of the feedforward bridge arm current f I rd As q-axis component of bridge arm voltage;
the d-axis component of the bridge arm voltage and the q-axis component of the bridge arm voltage form the dq component of the bridge arm voltage;
wherein ω is the operating frequency, C f Is the equivalent capacitance value, L, of an LCL filter connected with a bridge arm of a network-structured inverter f Is equivalent inductance value of LCL filter connected with bridge arm of network-structured inverter, U oq Is the q-axis component, U, of the output voltage of the grid-formed inverter od Is the d-axis component of the output voltage of the grid-formed inverter; i rq Is the q-axis component of the output current of the grid-formed inverter, I rd Is the d-axis component of the output current of the grid-formed inverter.
Preferably, the inverse transformation is to transform the dq component of the bridge arm voltage to the three-phase stationary abc coordinate to obtain a three-phase modulation wave.
Preferably, the multiple resonance controller is represented by formula (1):
wherein K is p As proportional term coefficient, K rh Is the resonance coefficient, n is the harmonic frequency, omega 0 Representing the resonant frequency and at the same time the frequency, ω, of the reference voltage in the grid system in which the grid-tied inverter is located cn And s represents a resonance angular frequency, j is j omega, and j is an imaginary unit.
Preferably, the proportional-integral controller is represented by formula (2):
wherein K is pc As proportional term coefficient, K ic Is the integral term coefficient.
Preferably, the method for executing control by using the virtual inertia power outer loop controller includes:
in the power outer loop, the actual current and voltage output by the grid-built inverter are detected by the power reference value and the detection circuit, the actual value of the output power is calculated, the frequency is calculated by the virtual inertia power outer loop controller, and the frequency is fed into the current and voltage double-loop control to be used as the reference value, so that the effect of controlling the grid-built inverter is achieved.
Preferably, the method for calculating the frequency through the virtual inertia power outer loop controller comprises the following steps:
the frequency ω is calculated by equation (3):
wherein, in the active control loop as the power outer loop, P ref P is the actual value of the power output by the grid-formed inverter and is calculated by the voltage and current signals measured at the output terminal of the grid-formed inverter, J is the virtual inertia, D is the damping factor, omega 0 An angular velocity rating of a virtual angular velocity of a virtual rotor of the grid-built inverter.
Preferably, the step 3 specifically includes:
The Sigmoid function is expressed as formula (9):
wherein x is an independent variable;
performing telescopic translation transformation on the Sigmoid function, and inputting virtual angular velocity of the virtual rotor ω1 The corresponding virtual inertia J is output, and the function expression after coordinate expansion transformation can be expressed as shown in a formula (10):
wherein omega 0 For angular velocity nominal value, i.e. 100 pi, J max 、J min respectively Representing defined virtual inertia maxima and minima.
A virtual inertia adaptive adjustment device of a mesh inverter, comprising:
the multiple resonance control module is used for executing control by using the inner ring voltage multiple resonance controller;
the virtual inertia power outer loop control module is used for executing control by using the virtual inertia power outer loop controller;
and the adjusting module is used for adjusting the virtual inertia by using the virtual inertia self-adaptive adjuster.
Preferably, the multiple resonance control module is further configured to convert the output voltage, the output current and the bridge arm current of the grid-formed inverter into a synchronous rotation dq coordinate system, input a reference voltage and an actual output voltage in voltage loop control, and output a reference value of the bridge arm current under the action of the multiple resonance controller; and then, entering current loop control, controlling a reference value and an actual value of bridge arm current through proportional integral to output a dq axis component of bridge arm voltage, generating a driving signal of a 6-way switching device of the grid-built inverter through a modulation module after inverse transformation, and driving the voltage type three-phase bridge inverter to output a required three-phase voltage current waveform.
Preferably, the multiple resonance control module is further configured to input the reference voltage and the output voltage of the grid-formed inverter as the actual output voltage in the voltage loop control, the d-axis component of the output voltage of the grid-formed inverter tracks the d-axis component reference value through the multiple resonance controller, and the output value of the multiple resonance controller superimposes the d-axis component of the output current and the q-axis compensation component- ωc of the feedforward output voltage f U oq As a reference value for the d-axis component of the bridge arm current; the bridge arm current tracks the d-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the d-axis component of the output voltage and the q-axis compensation component-omega L of the feedforward bridge arm current f I rq As d-axis component of bridge arm voltage;
the q-axis component of the output voltage of the grid-formed inverter tracks the q-axis component reference value by a multiple resonance controller whose output value superimposes the q-axis component of the output current and the d-axis compensation component- ωC of the feedforward output voltage f U od As a reference value for the q-axis component of the bridge arm current; the bridge arm current tracks the q-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the q-axis component of the output voltage and the d-axis compensation component-omega L of the feedforward bridge arm current f I rd As q-axis component of bridge arm voltage;
the d-axis component of the bridge arm voltage and the q-axis component of the bridge arm voltage form the dq component of the bridge arm voltage;
wherein ω is the operating frequency, C f Is the equivalent capacitance value, L, of an LCL filter connected with a bridge arm of a network-structured inverter f Is equivalent inductance value of LCL filter connected with bridge arm of network-structured inverter, U oq Is the q-axis component, U, of the output voltage of the grid-formed inverter od Is the d-axis component of the output voltage of the grid-formed inverter; i rq Is the q-axis component of the output current of the grid-formed inverter, I rd Is the d-axis component of the output current of the grid-formed inverter.
Preferably, the inverse transformation is to transform the dq component of the bridge arm voltage to the three-phase stationary abc coordinate to obtain a three-phase modulation wave.
Preferably, the multiple resonance controller is represented by formula (1):
wherein K is p As proportional term coefficient, K rh Is the resonance coefficient, n is the harmonic frequency, omega 0 Representing the resonant frequency and at the same time the frequency, ω, of the reference voltage in the grid system in which the grid-tied inverter is located cn And s represents a resonance angular frequency, j is j omega, and j is an imaginary unit.
Preferably, the proportional-integral controller is represented by formula (2):
wherein K is pc As proportional term coefficient, K ic Is the integral term coefficient.
Preferably, the virtual inertia power outer loop control module is further configured to detect an actual current voltage output by the grid-formed inverter through the power reference value and the detection circuit in the power outer loop, calculate an actual output power value of the power outer loop, calculate a frequency through the virtual inertia power outer loop controller, and give the frequency to the current voltage double loop control as a reference value, thereby achieving the function of controlling the grid-formed inverter.
Preferably, the method for calculating the frequency through the virtual inertia power outer loop controller comprises the following steps:
the frequency ω is calculated by equation (3):
wherein, in the active control loop as the power outer loop, P ref P is the actual value of the power output by the grid-formed inverter and is calculated by the voltage and current signals measured at the output terminal of the grid-formed inverter, J is the virtual inertia, D is the damping factor, omega 0 An angular velocity rating of a virtual angular velocity of a virtual rotor of the grid-built inverter.
Preferably, the adjusting module is further configured to perform telescopic translation transformation on the Sigmoid function, input a virtual angular velocity ω of the virtual rotor, output a corresponding virtual inertia J, and the function expression after coordinate telescopic transformation may be expressed as the expression (10):
Wherein omega 0 For angular velocity nominal value, i.e. 100 pi, J max 、J min respectively Representing defined virtual inertia maxima and minima.
A terminal comprising a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is configured to operate according to the instruction to perform the steps of the virtual inertia adaptive adjustment method of the grid-built inverter.
A computer readable storage medium having stored thereon a computer program which when executed by a processor implements the steps of a method for adaptive adjustment of virtual inertia of a mesh inverter.
Compared with the prior art, the virtual inertia self-adaptive adjusting method of the grid-structured inverter has the advantages that compared with the traditional voltage proportional integral control, the multiple resonance controllers are used in the voltage control loop, so that the problem of the power quality output when the inverter is grounded to a local nonlinear load can be effectively solved; the self-adaptive virtual inertia which can be changed according to frequency fluctuation is constructed by utilizing a self-adaptive control principle and utilizing a Sigmoid function, so that the potential of improving the frequency stability is effectively stimulated, the unstable occurrence of a system is prevented, and the dynamic response of the system is improved.
Drawings
FIG. 1 is a schematic diagram of an inner loop voltage multiple resonance controller according to the present application;
FIG. 2 is a schematic representation of a Sigmoid function for constructing adaptive virtual inertia adjustment as described in the present application;
FIG. 3 is a schematic diagram of a virtual inertia adaptive adjustment framework for a mesh inverter according to the present application;
fig. 4 is a flow chart of a method for adaptively adjusting virtual inertia of a grid-configured inverter according to the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely expressed with reference to the drawings in the embodiments of the present application. The embodiments of the application that are presented are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art without inventive faculty, are within the scope of the application.
In the control of the existing grid-built inverter, the problems that the power input fluctuation, frequency oscillation, output response speed and oscillation of the grid-built inverter cannot be simultaneously met and the like are caused by unknown system dynamics and difficult optimization of virtual inertia and damping parameters. In order to solve the problems, the rotor motion equation, primary frequency modulation and voltage regulation characteristics and virtual inertia of the synchronous generator can be utilized to enable the distributed power supply of the grid-formed inverter to simulate or partially simulate the synchronous generator frequency and voltage control characteristics from the external characteristics, so that the application aims to provide the virtual inertia self-adaptive regulation method applied to the grid-formed inverter, namely the grid-formed inverter, the virtual inertia self-adaptive regulator capable of changing the virtual inertia value according to the frequency fluctuation is constructed by utilizing the Sigmoid function so as to improve the dynamic response of the system, effectively resist the frequency mutation of load change of a micro-grid system where the grid-formed inverter is positioned, reduce the impact of the micro-power supply and the micro-grid of the inverter, prevent the system oscillation caused by disturbance, ensure the electric energy quality of the micro-grid, shorten the transient process, enable the frequency regulation to be completed quickly and accurately, improve the overall dynamic response of the system, and further improve the stability of the distributed power supply to be connected to the grid through the inverter, and have important significance for large-scale popularization of variable renewable energy sources and other distributed energy sources.
As shown in fig. 4, the method for adaptively adjusting virtual inertia of a grid-formed inverter according to the present invention includes:
performing control by using an inner-loop voltage multiple resonance controller, performing control by using a virtual inertia power outer-loop controller, and performing adjustment by using a virtual inertia self-adaptive adjuster; the method comprises the following steps:
step 1: performing control by using an inner ring voltage multiple resonance controller;
in a preferred but non-limiting embodiment of the present invention, the method for performing control using an inner loop voltage multiple resonance controller includes:
the inner ring voltage multiple resonance controller firstly converts the output voltage, the output current and the bridge arm current of the grid-formed inverter into a synchronous rotation dq coordinate system, inputs reference voltage and actual output voltage in voltage ring control, and then outputs a reference value of the bridge arm current under the action of the multiple resonance controller; and then, entering current loop control, controlling a reference value and an actual value of bridge arm current through proportional integral to output a dq axis component of bridge arm voltage, generating a driving signal of a 6-way switching device of the grid-built inverter through a modulation module after inverse transformation, and driving the voltage type three-phase bridge inverter to output a required three-phase voltage current waveform. The modulation module is used for comparing the three-phase modulation wave with the triangular carrier wave group to obtain the pwm signal of the 6-path switching device of the grid-structured inverter.
In a preferred but non-limiting embodiment of the present invention, the reference voltage and the actual output voltage are input in the voltage loop control, and then the reference value of the bridge arm current is output under the action of the multiple resonance controller; then, entering current loop control, and controlling the reference value and the actual value of the bridge arm current through proportional integral to output the dq axis component of the bridge arm voltage, wherein the method comprises the following steps:
in the voltage loop control, a reference voltage and an output voltage of a grid-formed inverter as an actual output voltage are input, a d-axis component of the output voltage of the grid-formed inverter tracks a d-axis component reference value through a multiple resonance controller, and the output value of the multiple resonance controller superimposes a d-axis component of an output current and a q-axis compensation component-omega C of a feedforward output voltage f U oq As a reference value for the d-axis component of the bridge arm current; the bridge arm current tracks the d-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the d-axis component of the output voltage and the q-axis compensation component-omega L of the feedforward bridge arm current f I rq As d-axis component of bridge arm voltage; similarly, the q-axis component of the bridge arm voltage is available, namely:
the q-axis component of the output voltage of the grid-formed inverter tracks the q-axis component reference value by a multiple resonance controller whose output value superimposes the q-axis component of the output current and the d-axis compensation component- ωC of the feedforward output voltage f U od As a reference value for the q-axis component of the bridge arm current; the bridge arm current tracks the q-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the q-axis component of the output voltage and the d-axis compensation component-omega L of the feedforward bridge arm current f I rd As q-axis component of bridge arm voltage;
the d-axis component of the bridge arm voltage and the q-axis component of the bridge arm voltage form the dq component of the bridge arm voltage;
wherein omegaIs the working frequency, C f Is the equivalent capacitance value, L, of an LCL filter connected with a bridge arm of a network-structured inverter f Is equivalent inductance value of LCL filter connected with bridge arm of network-structured inverter, U oq Is the q-axis component, U, of the output voltage of the grid-formed inverter od Is the d-axis component of the output voltage of the grid-formed inverter; i rq Is the q-axis component of the output current of the grid-formed inverter, I rd Is the d-axis component of the output current of the grid-formed inverter.
In a preferred but non-limiting embodiment of the present invention, the inverse transformation is to transform the dq component of the bridge arm voltage to the three-phase static abc coordinate to obtain a three-phase modulation wave, and generate a driving signal of the 6-way switching device through the modulation module, so that the grid-formed inverter outputs a voltage current waveform. When the power grid system where the grid-structured inverter is positioned normally operates, the direct current chain capacitor representing distributed energy outputs constant direct current voltage, the three-phase bridge inverter outputs required three-phase bridge arm voltage through the three-phase bridge inverter, and the three-phase bridge inverter outputs stable three-phase alternating current voltage through the LCL filter to be connected with a large power grid.
In a preferred but non-limiting embodiment of the invention, as shown in fig. 1, the multiple resonance controller used for voltage is shown in formula (1):
wherein K is p As proportional term coefficient, K rh Is the resonance coefficient, n is the harmonic frequency, omega 0 Representing the resonant frequency and at the same time the frequency, ω, of the reference voltage in the grid system in which the grid-tied inverter is located cn And s represents a resonance angular frequency, j is j omega, and j is an imaginary unit.
In a preferred but non-limiting embodiment of the present invention, the proportional-integral controller used for the current is represented by formula (2):
wherein K is pc As proportional term coefficient, K ic Is the integral term coefficient.
Compared with the traditional voltage proportional integral control, the multiple resonance controller used in the voltage control loop can effectively inhibit harmonic components when the grid-type inverter is connected with a local nonlinear load, and improve the output power quality.
Step 2: executing control by using the virtual inertia power outer loop controller;
in a preferred but non-limiting embodiment of the present invention, the method for performing control by using the virtual inertia power outer loop controller includes:
in the power outer loop, the actual current and voltage output by the grid-built inverter are detected by the power reference value and the detection circuit, the actual value of the output power is calculated, the frequency is calculated by the virtual inertia power outer loop controller, and the frequency is fed into the current and voltage double-loop control to be used as the reference value, so that the effect of controlling the grid-built inverter is achieved. The detection circuit comprises a voltage sensor and a current sensor which are arranged at the output terminal of the grid-formed inverter, wherein the voltage sensor and the current sensor respectively measure voltage and current signals at the output terminal of the grid-formed inverter, and then the measured voltage and current signals are multiplied to obtain the actual value of the output power.
In a preferred but non-limiting embodiment of the present invention, the method for calculating the frequency through the virtual inertia power outer loop controller includes:
the frequency ω is calculated by equation (3):
wherein, in the active control loop as the power outer loop, P ref P is the actual value of the power output by the grid-formed inverter and is calculated by the voltage and current signals measured at the output terminal of the grid-formed inverter, J is the virtual inertia, D is the damping factor, omega 0 Virtual angular velocity of virtual rotor of grid-built inverterAngular velocity rating. The active control loop simulates the speed governor of a synchronous generator. It adjusts the frequency by controlling the virtual torque, the adjusting capacity of which is related to the virtual inertia. The change in output active power caused by the change in frequency is described by a damping coefficient. The control expression is obtained by Laplacian transformation of a synchronous generator rotor mechanical equation.
Compared with the traditional droop control outer ring, the virtual inertia power outer ring controller can improve the frequency stability of the micro-grid where the grid-built inverter is located by increasing the inertia and damping of the distributed power generation system.
As shown in fig. 2, step 3: the virtual inertia is adjusted by using the virtual inertia adaptive adjuster. I.e. an adaptive virtual inertia adjuster is constructed based on Sigmoid functions to perform the adjustment.
Specifically, in step 3, a small signal model of virtual inertia power outer loop control is constructed, and a transfer function of an input power reference value and an output power actual value of the grid-built inverter under the condition of small disturbance can be obtained as shown in formula (4):
wherein Δp is a differential value of an actual value of power output from the grid-formed inverter, and p ref Is a derivative of the power reference value,e is the effective value of the output voltage of the grid-structured inverter, U is the effective value of the voltage at the common point of the power grid where the grid-structured inverter is positioned, and X is the impedance of the output line of the grid-structured inverter.
The transfer function of the input power reference value and the output frequency of the grid-formed inverter is shown in formula (5):
wherein Δω is a differential amount of the frequency output by the grid-formed inverter;
both characteristic equations are shown in formula (6):
ω 0 Js 2 +ω 0 D p s+A＝0 (6)
the natural oscillation angular frequency omega of the system can be obtained n And the damping ratio ζ satisfies the formula (7):
for overshoot M p And adjust time t s Can be calculated by the following formula (8):
when ζ is more than 0 and less than 1, the overshoot of the power grid system where the grid-structured inverter is located increases along with ζ reduction, namely, when virtual inertia J increases, the smaller the damping ratio of the power grid system where the grid-structured inverter is located is, the greater the overshoot of the power grid system where the grid-structured inverter is located is, and the damping ratio ζ of the power grid system where the grid-structured inverter is generally set to be more than 0.4; when the damping ratio of the power grid system where the grid-structured inverter is positioned is more than 0.8 and less than ζ and less than 1, the response speed of the power grid system where the grid-structured inverter is positioned is obviously slowed down, so that the damping ratio cannot be excessively large, and the damping ratio ζ of the power grid system where the grid-structured inverter is positioned is generally less than 0.8; the two points are combined, the damping ratio is more than 0.4 and less than 0.8, and D is maintained p Unchanged, find J min ＜J＜J max 。
In conventional virtual inertial power outer loop control, the virtual inertia J is a constant. The fixed coefficient inertia control parameters are difficult to set, and the voltage waveform generated by the power outer loop control grid-structured inverter is not ideal when interference is different. In practical applications, the virtual inertia J should be dynamically adjusted according to the change of the grid system in which the grid-tied inverter is located. When the frequency fluctuation is large, J should be increased to increase the supporting capacity of the grid-type inverter to the frequency; after the frequency deviation is gradually reduced, the value of the virtual inertia J should be rapidly reduced so as to reduce the adjustment time. In the traditional virtual inertia power outer loop control, the fixed virtual inertia J cannot simultaneously meet the dynamic and quick requirements of different disturbance stages. Therefore, the invention designs a self-adaptive virtual inertia regulator constructed based on a Sigmoid function.
Reducing inverter output frequency deviation is a primary task for virtual inertia power outer loop control. In the power outer loop control, the value of the moment of inertia J is different, the dynamic response of the system is directly influenced, when the value of the moment of inertia J is smaller, the system response is faster, but the support to the frequency is not obvious, and when the value of the moment of inertia J is overlarge, the adjusting time is greatly prolonged, but the frequency supporting effect is obvious. When the acceleration of ω is faster and the frequency deviation is larger, a larger J is required to attenuate Although this would extend the settling time required for the frequency to fall within the settling zone to some extent.
Based on the principle, the traditional constant endowing method is changed to the virtual inertia J in the active control loop, and the method is converted into the self-adaptive virtual inertia J which can be changed according to frequency fluctuation by utilizing a Sigmoid function so as to better control the active control loop;
in a preferred but non-limiting embodiment of the present invention, the step 3 specifically includes:
the basic form of the Sigmoid function can be expressed as shown in equation (9):
wherein x is an independent variable;
as shown in fig. 3, the Sigmoid function is subjected to telescopic translation transformation, the virtual angular velocity ω of the virtual rotor is input, the corresponding virtual inertia J is output, and the function expression after the coordinate telescopic transformation can be expressed as the expression (10):
wherein omega 0 For angular velocity nominal value, i.e. 100 pi, J max 、J min respectively Representing the maximum and minimum values of the defined virtual inertia, which can be calculated according to the requirement that zeta is more than 0.4 and less than 0.8.
The principle of constructing the self-adaptive virtual inertia regulator based on the Sigmoid function is as follows: calculating the J value of the virtual inertia to be adopted at present according to the frequency deviation amount caused by disturbance at any moment, and when the frequency deviation amount is smaller, the calculated J value of the virtual inertia is smaller and is close to J min In order to reduce the adjustment time as much as possible, the output waveform of the grid-formed inverter is restored to a stable state in a short time; when the frequency deviation caused by disturbance is large, the calculated virtual inertia J value is also large and is close to J max To improve the frequency supporting capability of the grid-built inverter. Therefore, the value of the self-adaptive virtual inertia J which can be changed according to the frequency fluctuation is constructed by utilizing the Sigmoid function, which has important significance for improving the dynamic response of the power grid system where the grid-structured inverter is located, can effectively excite the potential for improving the frequency stability, and prevents the occurrence of instability of the power grid system where the grid-structured inverter is located.
As shown in fig. 3, when the grid system where the grid-formed inverter is located is operating normally, a constant dc voltage is output by a dc link capacitor representing distributed energy, a sampling circuit samples a voltage and a current to calculate power, then a virtual inertia power outer loop controller (wherein the virtual inertia J is calculated by a Sigmoid function) calculates a reference frequency and a voltage amplitude to a voltage and current double loop control module (a voltage using a multiple resonance controller and a current using a proportional integral controller) to output an inverter control signal, a three-phase bridge inverter is controlled to output a required three-phase bridge arm voltage, and a desired stable three-phase ac voltage is output through a filter LCL and is connected to a large grid.
The flow of the virtual inertia self-adaptive adjusting method of the grid-connected inverter formed by the power grid is shown in fig. 4, when the system is in normal operation, the detecting circuit detects the output current and voltage of the inverter in real time, the power value is calculated by the power calculator, and then the frequency and voltage of the system are calculated by the virtual inertia power outer loop algorithm. When the frequency difference delta omega between the system frequency and the grid frequency is increased, a larger virtual inertia J is generated through the constructed Sigmoid function, so that the voltage and the frequency reference value required by the inverter are calculated through power control, and the fluctuation of the frequency is restrained. When the frequency difference delta omega between the system frequency and the grid frequency is reduced, smaller virtual inertia J is generated through the constructed Sigmoid function, the response time of the system is shortened, and the voltage and frequency reference value required by the inverter at the moment are calculated through power control. After the inverter receives the reference value given by the outer loop power control, a modulation wave is generated through voltage-current double-loop control of the inner loop, and then a driving signal of a 6-path switching device is generated through a modulation module, so that the electric inverter is driven to output a required voltage-current waveform, and at the moment, a detection circuit can detect the current-voltage output by the inverter in real time, and the current-voltage returns to the first step and then continuously and circularly operates.
The invention relates to a virtual inertia self-adaptive adjusting device of a grid-structured inverter, which comprises:
the multiple resonance control module is used for executing control by using the inner ring voltage multiple resonance controller;
the virtual inertia power outer loop control module is used for executing control by using the virtual inertia power outer loop controller;
and the adjusting module is used for adjusting the virtual inertia by using the virtual inertia self-adaptive adjuster.
In a preferred but non-limiting embodiment of the present invention, the multiple resonance control module is further configured to convert the output voltage, the output current and the bridge arm current of the grid-formed inverter into the synchronous rotation dq coordinate system, input the reference voltage and the actual output voltage in the voltage loop control, and output the reference value of the bridge arm current under the action of the multiple resonance controller; and then, entering current loop control, controlling a reference value and an actual value of bridge arm current through proportional integral to output a dq axis component of bridge arm voltage, generating a driving signal of a 6-way switching device of the grid-built inverter through a modulation module after inverse transformation, and driving the voltage type three-phase bridge inverter to output a required three-phase voltage current waveform.
In a preferred but non-limiting embodiment of the present invention, the multiple resonance control module is further configured to input the reference voltage and the output voltage of the grid-formed inverter as the actual output voltage in the voltage loop control, the d-axis component of the output voltage of the grid-formed inverter tracks the d-axis component reference value through the multiple resonance controller, and the output value of the multiple resonance controller superimposes the d-axis component of the output current and the q-axis compensation component- ωc of the feedforward output voltage f U oq As a reference value for the d-axis component of the bridge arm current; the bridge arm current tracks the d-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the d-axis component of the output voltage and the q-axis compensation component-omega L of the feedforward bridge arm current f I rq As d-axis component of bridge arm voltage; similarly, the q-axis component of the bridge arm voltage is available, namely:
the q-axis component of the output voltage of the grid-formed inverter tracks the q-axis component reference value by a multiple resonance controller whose output value superimposes the q-axis component of the output current and the d-axis compensation component- ωC of the feedforward output voltage f U od As a reference value for the q-axis component of the bridge arm current; the bridge arm current tracks the q-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the q-axis component of the output voltage and the d-axis compensation component-omega L of the feedforward bridge arm current f I rd As q-axis component of bridge arm voltage;
the d-axis component of the bridge arm voltage and the q-axis component of the bridge arm voltage form the dq component of the bridge arm voltage;
wherein ω is the operating frequency, C f Is the equivalent capacitance value, L, of an LCL filter connected with a bridge arm of a network-structured inverter f Is equivalent inductance value of LCL filter connected with bridge arm of network-structured inverter, U oq Is the q-axis component, U, of the output voltage of the grid-formed inverter od Is the d-axis component of the output voltage of the grid-formed inverter; i rq Is the output of a grid-built inverterQ-axis component of the outgoing current, I rd Is the d-axis component of the output current of the grid-formed inverter.
In a preferred but non-limiting embodiment of the present invention, the inverse transformation is to transform the dq component of the bridge arm voltage to the three-phase static abc coordinate to obtain a three-phase modulation wave, and generate a driving signal of the 6-way switching device through the modulation module, so that the grid-formed inverter outputs a voltage current waveform.
In a preferred but non-limiting embodiment of the present invention, the multiple resonance controller used for voltage is represented by formula (1):
wherein K is p As proportional term coefficient, K rh Is the resonance coefficient, n is the harmonic frequency, omega 0 Representing the resonant frequency and at the same time the frequency, ω, of the reference voltage in the grid system in which the grid-tied inverter is located cn And s represents a resonance angular frequency, j is j omega, and j is an imaginary unit.
In a preferred but non-limiting embodiment of the present invention, the proportional-integral controller used for the current is represented by formula (2):
wherein K is pc As proportional term coefficient, K ic Is the integral term coefficient.
In a preferred but non-limiting embodiment of the present invention, the virtual inertia power outer loop control module is further configured to calculate an actual output power value of the output power of the grid-formed inverter by detecting an actual current voltage output by the grid-formed inverter through the power reference value and the detection circuit in the power outer loop, calculate a frequency through the virtual inertia power outer loop controller, and provide the frequency to the current voltage double loop control as a reference value, thereby achieving the function of controlling the grid-formed inverter.
In a preferred but non-limiting embodiment of the present invention, the method for calculating the frequency through the virtual inertia power outer loop controller includes:
the frequency ω is calculated by equation (3):
wherein, in the active control loop as the power outer loop, P ref P is the actual value of the power output by the grid-formed inverter and is calculated by the voltage and current signals measured at the output terminal of the grid-formed inverter, J is the virtual inertia, D is the damping factor, omega 0 An angular velocity rating of a virtual angular velocity of a virtual rotor of the grid-built inverter.
In a preferred but non-limiting embodiment of the present invention, the adjusting module is further configured to perform telescopic translation transformation on the Sigmoid function, input the virtual angular velocity ω of the virtual rotor, output the corresponding virtual inertia J, and the function expression after coordinate telescopic transformation may be expressed as the expression (10):
wherein omega 0 For angular velocity nominal value, i.e. 100 pi, J max 、J min respectively Representing the maximum and minimum values of the defined virtual inertia, which can be calculated according to the requirement that zeta is more than 0.4 and less than 0.8.
The terminal comprises a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is configured to operate according to the instruction to perform the steps of the virtual inertia adaptive adjustment method of the grid-built inverter.
The computer readable storage medium of the present invention has stored thereon a computer program which, when executed by a processor, implements the steps of the virtual inertia adaptive adjustment method of a mesh inverter.
Compared with the prior art, the virtual inertia self-adaptive adjusting method of the grid-structured inverter has the advantages that compared with the traditional voltage proportional integral control, the multiple resonance controllers are used in the voltage control loop, so that the problem of the power quality output when the inverter is grounded to a local nonlinear load can be effectively solved; the self-adaptive virtual inertia which can be changed according to frequency fluctuation is constructed by utilizing a self-adaptive control principle and utilizing a Sigmoid function, so that the potential of improving the frequency stability is effectively stimulated, the unstable occurrence of a system is prevented, and the dynamic response of the system is improved.
The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.
The computer readable storage medium may be a tangible device that can hold and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: portable computer disks, hard disks, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static Random Access Memory (SRAM), portable compact disk read-only memory (CD-ROM), digital Versatile Disks (DVD), memory sticks, floppy disks, mechanical coding devices, punch cards or in-groove structures such as punch cards or grooves having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media, as used herein, are not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., optical pulses through fiber optic cables), or electrical signals transmitted through wires.
The computer readable program instructions described herein may be downloaded from a computer readable storage medium to a respective computing/processing device or to an external computer or external storage device over a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers and/or edge servers. The network interface card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium in the respective computing/processing device.
Computer program instructions for performing the operations of the present disclosure can be assembly instructions, instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, c++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions may be executed entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, aspects of the present disclosure are implemented by personalizing electronic circuitry, such as programmable logic circuitry, field Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), with state information of computer readable program instructions, which can execute the computer readable program instructions.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (11)
1. The virtual inertia self-adaptive adjusting method of the grid-built inverter is characterized by comprising the following steps of:
step 1: performing control by using an inner ring voltage multiple resonance controller;
step 2: executing control by using the virtual inertia power outer loop controller;
step 3: executing adjustment on the virtual inertia by using a virtual inertia self-adaptive adjuster;
the method for executing control by using the inner loop voltage multiple resonance controller comprises the following steps:
the inner ring voltage multiple resonance controller firstly converts the output voltage, the output current and the bridge arm current of the grid-formed inverter into a synchronous rotation dq coordinate system, inputs reference voltage and actual output voltage in voltage ring control, and then outputs a reference value of the bridge arm current under the action of the multiple resonance controller; then, entering current loop control, controlling a reference value and an actual value of bridge arm current through proportional integral to output a dq axis component of bridge arm voltage, generating a driving signal of a 6-way switching device of the grid-built inverter through a modulation module after inverse transformation so as to drive the voltage type three-phase bridge inverter to output a required three-phase voltage current waveform;
The method for executing control by using the virtual inertia power outer loop controller comprises the following steps:
in the power outer loop, the actual current and voltage output by the grid-built inverter are detected through a power reference value and a detection circuit, the actual value of the output power is calculated, the frequency is calculated through a virtual inertia power outer loop controller, and the frequency is fed into the current and voltage double-loop control to serve as a reference value, so that the effect of controlling the grid-built inverter is achieved;
the step 3 specifically includes:
the Sigmoid function is expressed as shown in formula (9):
wherein x is an independent variable;
performing telescopic translation transformation on the Sigmoid function, and inputting virtual angular velocity of the virtual rotor ω1 The corresponding virtual inertia J is output, and the function expression after coordinate expansion transformation can be expressed as shown in a formula (10):
wherein omega 0 An angular velocity rating of 100 pi, J, which is the virtual angular velocity of the virtual rotor of the grid-built inverter max 、J min Representing defined virtual inertia maxima and minima, respectively.
2. The adaptive virtual inertia adjustment method of the grid-formed inverter according to claim 1, wherein the reference voltage and the actual output voltage are input in the voltage loop control, and then the reference value of the bridge arm current is output under the action of the multiple resonance controller; then, entering current loop control, and controlling the reference value and the actual value of the bridge arm current through proportional integral to output the dq axis component of the bridge arm voltage, wherein the method comprises the following steps:
In the voltage loop control, a reference voltage and an output voltage of a grid-formed inverter as an actual output voltage are input, a d-axis component of the output voltage of the grid-formed inverter tracks a d-axis component reference value through a multiple resonance controller, and the output value of the multiple resonance controller superimposes a d-axis component of an output current and a q-axis compensation component-omega C of a feedforward output voltage f U oq As a reference value for the d-axis component of the bridge arm current; the bridge arm current tracks the d-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the d-axis component of the output voltage and the q-axis compensation component-omega L of the feedforward bridge arm current f I rq As d-axis component of bridge arm voltage;
the q-axis component of the output voltage of the grid-formed inverter tracks the q-axis component reference value by a multiple resonance controller whose output value superimposes the q-axis component of the output current and the d-axis compensation component- ωC of the feedforward output voltage f U od As a reference value for the q-axis component of the bridge arm current; the bridge arm current tracks the q-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the q-axis component of the output voltage and the d-axis compensation component-omega L of the feedforward bridge arm current f I rd As q-axis component of bridge arm voltage;
The d-axis component of the bridge arm voltage and the q-axis component of the bridge arm voltage form the dq component of the bridge arm voltage;
wherein ω is the operating frequency, C f Is the equivalent capacitance value, L, of an LCL filter connected with a bridge arm of a network-structured inverter f Is equivalent inductance value of LCL filter connected with bridge arm of network-structured inverter, U oq Is the q-axis component, U, of the output voltage of the grid-formed inverter od Is the d-axis component of the output voltage of the grid-formed inverter; i rq Is the q-axis component of the output current of the grid-formed inverter, I rd Is the d-axis component of the output current of the grid-formed inverter.
3. The method for adaptively adjusting virtual inertia of a mesh inverter according to claim 1, wherein the inverse transformation is to transform the dq component of the bridge arm voltage to a three-phase stationary abc coordinate to obtain a three-phase modulated wave.
4. The method for adaptively adjusting the virtual inertia of a mesh inverter according to claim 1, wherein the multiple resonance controller is represented by formula (1):
wherein K is p As proportional term coefficient, K rh Is the resonance coefficient, n is the harmonic frequency, omega 2 The resonance frequency is indicated as such,at the same time, the frequency omega of the reference voltage in the power grid system where the grid-structured inverter is positioned cn And s represents a resonance angular frequency, j is j omega, and j is an imaginary unit.
5. The method for adaptively adjusting the virtual inertia of a mesh inverter according to claim 1, wherein the proportional-integral controller is represented by formula (2):
wherein K is pc As proportional term coefficient, K ic Is the integral term coefficient.
6. The method for adaptively adjusting the virtual inertia of the grid-configured inverter according to claim 1, wherein the method for calculating the frequency through the virtual inertia power outer loop controller comprises the steps of:
the operating frequency ω is calculated by equation (3):
wherein, in the active control loop as the power outer loop, P ref P is the actual value of the power output by the grid-formed inverter and is calculated by the voltage and current signals measured at the output terminal of the grid-formed inverter, J is the virtual inertia, D is the damping factor, omega 0 An angular velocity rating of a virtual angular velocity of a virtual rotor of the grid-built inverter.
7. A virtual inertia adaptive adjustment device for a mesh inverter, comprising:
the multiple resonance control module is used for executing control by using the inner ring voltage multiple resonance controller;
the virtual inertia power outer loop control module is used for executing control by using the virtual inertia power outer loop controller;
The adjusting module is used for adjusting the virtual inertia by using the virtual inertia self-adaptive adjuster;
the multiple resonance control module is also used for firstly converting the output voltage, the output current and the bridge arm current of the grid-formed inverter into a synchronous rotation dq coordinate system, inputting a reference voltage and an actual output voltage in voltage loop control, and outputting a reference value of the bridge arm current under the action of the multiple resonance controller; then, entering current loop control, controlling a reference value and an actual value of bridge arm current through proportional integral to output a dq axis component of bridge arm voltage, generating a driving signal of a 6-way switching device of the grid-built inverter through a modulation module after inverse transformation so as to drive the voltage type three-phase bridge inverter to output a required three-phase voltage current waveform;
the virtual inertia power outer loop control module is also used for detecting the actual current and voltage output by the grid-built inverter in the power outer loop through the power reference value and the detection circuit to calculate the actual value of the output power, calculating the frequency through the virtual inertia power outer loop controller, and feeding the frequency into the current and voltage double-loop control to serve as a reference value, so that the effect of controlling the grid-built inverter is achieved;
The method for calculating the frequency through the virtual inertia power outer loop controller comprises the following steps:
the operating frequency ω is calculated by equation (3):
wherein, in the active control loop as the power outer loop, P ref P is the actual value of the power output by the grid-formed inverter and is calculated by the voltage and current signals measured at the output terminal of the grid-formed inverter, J is the virtual inertia, D is the damping factor, omega 0 An angular velocity rating of a virtual angular velocity of a virtual rotor of the grid-formed inverter;
the adjusting module is also used for carrying out telescopic translation transformation on the Sigmoid function and inputting the virtual angular velocity of the virtual rotor ω1 The corresponding virtual inertia J is output, and the function expression after coordinate expansion transformation can be expressed as shown in a formula (10):
wherein omega 0 An angular velocity rating of 100 pi, J, which is the virtual angular velocity of the virtual rotor of the grid-built inverter max 、J min Representing defined virtual inertia maxima and minima, respectively.
8. The virtual inertia adaptive adjustment device of claim 7, wherein the multiple resonance control module is further configured to input a reference voltage and an output voltage of the mesh inverter as an actual output voltage in voltage loop control, a d-axis component of the output voltage of the mesh inverter tracks a d-axis component reference value through a multiple resonance controller, and an output value of the multiple resonance controller superimposes a d-axis component of an output current and a q-axis compensation component- ωc of a feedforward output voltage f U oq As a reference value for the d-axis component of the bridge arm current; the bridge arm current tracks the d-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the d-axis component of the output voltage and the q-axis compensation component-omega L of the feedforward bridge arm current f I rq As d-axis component of bridge arm voltage;
the q-axis component of the output voltage of the grid-formed inverter tracks the q-axis component reference value by a multiple resonance controller whose output value superimposes the q-axis component of the output current and the d-axis compensation component- ωC of the feedforward output voltage f U od As a reference value for the q-axis component of the bridge arm current; the bridge arm current tracks the q-axis component reference value through a proportional-integral controller, and the output value of the proportional-integral controller overlaps the q-axis component of the output voltage and the d-axis compensation component-omega L of the feedforward bridge arm current f I rd As q-axis component of bridge arm voltage;
the d-axis component of the bridge arm voltage and the q-axis component of the bridge arm voltage form the dq component of the bridge arm voltage;
wherein ω is the operating frequency, C f Is the equivalent capacitance value, L, of an LCL filter connected with a bridge arm of a network-structured inverter f Is equivalent inductance value of LCL filter connected with bridge arm of network-structured inverter, U oq Is the q-axis component, U, of the output voltage of the grid-formed inverter od Is the d-axis component of the output voltage of the grid-formed inverter; i rq Is the q-axis component of the output current of the grid-formed inverter, I rd Is the d-axis component of the output current of the grid-formed inverter;
the inverse transformation is to transform the dq component of the bridge arm voltage to a three-phase static abc coordinate to obtain a three-phase modulation wave;
the multiple resonance controller is shown in formula (1):
wherein K is p As proportional term coefficient, K rh Is the resonance coefficient, n is the harmonic frequency, omega 2 Representing the resonant frequency and at the same time the frequency, ω, of the reference voltage in the grid system in which the grid-tied inverter is located cn And s represents a resonance angular frequency, j is j omega, and j is an imaginary unit.
9. The adaptive virtual inertia adjustment device for a mesh inverter according to claim 7, wherein the proportional-integral controller is represented by formula (2):
wherein K is pc As proportional term coefficient, K ic Is the integral term coefficient.
10. A terminal comprising a processor and a storage medium; it is characterized in that the method comprises the steps of,
the storage medium is used for storing instructions;
the processor is configured to operate according to the instructions to perform the steps of the virtual inertia adaptive adjustment method of a mesh inverter according to any one of claims 1-6.
11. A computer readable storage medium having stored thereon a computer program, characterized in that the program when executed by a processor realizes the steps of the virtual inertia adaptive adjustment method of a mesh inverter according to any of claims 1-6.
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