CN117239852A - Virtual synchronous machine control method and device based on power selection and voltage feedback - Google Patents
Virtual synchronous machine control method and device based on power selection and voltage feedback Download PDFInfo
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Abstract
The application discloses a virtual synchronous machine control method and a device based on power selection and voltage feedback, which are applied to an energy storage virtual synchronous machine used by an energy storage system during grid connection or grid disconnection, wherein the method comprises the following steps: determining an active power setting and a reactive power setting according to the connection relation between the virtual synchronous machine and a public power grid; according to the active power, a given and determined angle reference value is adopted, and a first control signal of the virtual synchronous machine voltage output target frequency is controlled according to the angle reference value; and according to the reactive power, a voltage reference value is given and determined, and a second control signal of the voltage output target amplitude of the virtual synchronous machine is controlled according to the voltage reference value. The frequency and the amplitude of the output voltage of the virtual synchronous machine can be adjusted through the angle reference value and the voltage reference value by setting the angle reference value for the active power and the voltage reference value for the reactive power, so that the frequency offset and the voltage offset are eliminated, and the running stability of the virtual synchronous machine is improved.
Description
Technical Field
The invention relates to the field of virtual synchronous machines, in particular to a virtual synchronous machine control method and device based on power selection and voltage feedback.
Background
In order to improve the average fluidity and realize the decoupling of active and reactive control during the parallel operation, the current general virtual synchronous machine operation control generally introduces virtual impedance (Rvsg+jXvsg) into a load control loop, and on the synchronous machine output control, the power is controlled by mechanical torque, the reactive power is controlled by an excitation system, and the two are independently operated. However, due to the voltage drop caused by the virtual impedance, the problems of active-frequency sagging and reactive-voltage sagging in the traditional virtual synchronous machine control method are difficult to avoid, the output voltage is inconsistent with the actual given voltage when the off-grid belt is in load operation, and damage to load equipment can be caused when the output voltage is too low.
Disclosure of Invention
The embodiment of the invention provides a virtual synchronous machine control method and device based on power selection and voltage feedback, which are used for accelerating dynamic feedback of voltage when power grid voltage fluctuates and eliminating frequency offset and voltage offset through frequency modulation and voltage regulation.
In a first aspect, an embodiment of the present invention provides a virtual synchronous machine control method based on power selection and voltage feedback, which is applied to an energy storage virtual synchronous machine used by an energy storage system during grid connection or off-grid, where the method includes:
Determining an active power setting and a reactive power setting according to the connection relation between the virtual synchronous machine and a public power grid, wherein the active power setting refers to input power in an active power control flow of the virtual synchronous machine, and the reactive power setting refers to input power in a reactive power control flow of the virtual synchronous machine; according to the active power, a given and determined angle reference value is used for controlling a first control signal of the virtual synchronous machine voltage output target frequency according to the angle reference value, wherein the first control signal is used for eliminating the active-frequency sagging phenomenon of the virtual synchronous machine in the running process; and according to the reactive power given and determined voltage reference value, controlling a second control signal of the voltage output target amplitude of the virtual synchronous machine according to the voltage reference value, wherein the second control signal is used for eliminating the reactive power-voltage sagging phenomenon of the virtual synchronous machine in the running process.
The determining the active power setting and the reactive power setting according to the connection relation between the virtual synchronous machine and the public power grid comprises the following steps: judging whether the connection relation between the virtual synchronous machine and the public power grid is off-grid or the connection relation is switched to off-grid; if the connection relation between the virtual synchronous machine and the public power grid is judged to be off-grid or the connection relation is judged to be switched to be off-grid, the active power is given as load active power, and the reactive power is given as load reactive power; and if the connection relation between the virtual synchronous machine and the public power grid is judged to be grid connection, the active power is given as grid connection active power, and the reactive power is given as grid connection reactive power.
Wherein the determining the angle reference value according to the active power setting comprises: acquiring a first difference value between the active power setting and active power feedback, wherein the active power setting is an actual value of the virtual synchronous machine active power setting; determining damping power according to the first difference value, the damping coefficient and the inertia coefficient; determining an angle reference value according to the damping power, the first difference value and the rated angular frequency; the damping power and the angle reference value are expressed as follows:
wherein,θ ref as a result of the angle reference value,P refAct for a given of the active power,P fb in order to use the power feedback for work,P damp for the said damping power to be sufficient,ω base for the said nominal angular frequency of the said angle,Jsas a function of the coefficient of inertia of the said mass,sfor representing a time-domain integration in the frequency domain,Dis the damping coefficient.
Wherein the first control signal for controlling the virtual synchronous machine voltage output target frequency according to the angle reference value includes: the first control signal is used for taking the angle reference value as the frequency of the virtual synchronous machine voltage output to realize frequency modulation so as to eliminate the phenomenon of active-frequency sagging.
Wherein said determining a voltage reference value from said reactive power setting comprises: obtaining a second difference value between a given value of the module voltage and feedback of the module voltage; obtaining a first voltage feedback value from the second difference through PI; obtaining a third sum value of the reactive power given value and the first voltage feedback value, wherein the third sum value is an actual value of the reactive power given value of the virtual synchronous machine; acquiring a fourth difference value between the third sum value and the reactive power feedback; obtaining a second voltage feedback value from the fourth difference value through PI; determining a voltage reference value according to the second voltage feedback value, the rated voltage, the module value current feedback, the virtual impedance and the low-pass filter, wherein the virtual impedance is the sum of the virtual resistance and the virtual inductance of the virtual synchronous machine, the product of the virtual impedance and the module value current feedback passes through the low-pass filter and then outputs voltage feedforward, and the voltage feedforward is used for ensuring the working voltage stability of the virtual synchronous machine when the power grid voltage fluctuates;
The expression of the voltage reference value is as follows:
wherein,V ref as a result of the voltage reference value,V base for the said voltage rating to be given,Q refAct the virtual synchronous machine reactive power is given an actual value,Q fb for the reactive power feedback,k QP andk Qi in the form of a PI, the phase difference is,sfor representing a time-domain integration in the frequency domain,Ifor the feedback of the current to the module,R vsg for the purpose of the virtual resistance,X vsg for the purpose of the virtual inductance described above,jis imaginary unit, 1/(1 +)Ts) Is the low pass filter.
Wherein the second control signal for controlling the virtual synchronous machine voltage output target amplitude according to the voltage reference value includes: the second control signal is used for taking the voltage reference value as the amplitude of the voltage output of the virtual synchronous machine to realize voltage regulation so as to eliminate the reactive power-voltage sag phenomenon.
And the product of the virtual impedance and the module value current feedback passes through the low-pass filter to obtain a third voltage feedback value, and the low-pass filter reduces the third voltage feedback value by changing the cut-off frequency, so that the cut-off frequency is modified to reduce the third voltage feedback value to 0 when the virtual synchronous machine is in grid-connected operation, and the unstable power grid caused by excessive reactive power generated when the power grid voltage fluctuates is prevented.
Wherein after said determining the damping power from the first difference, the damping coefficient, and the inertia coefficient, the method further comprises: and adding an amplitude limiting link, wherein the amplitude limiting link refers to the process of opening a root number on the damping power and is used for limiting the active deviation.
In a second aspect, an embodiment of the present invention provides a virtual synchronous machine control device based on power selection and voltage feedback, including:
the power selection module is used for determining an active power given value and a reactive power given value according to the connection relation between the virtual synchronous machine and the public power grid;
the parameter determining module is used for determining an angle reference value according to the active power setting, controlling a first control signal of the virtual synchronous machine voltage output target frequency according to the angle reference value, wherein the first control signal is used for eliminating the active-frequency sagging phenomenon of the virtual synchronous machine in the running process; and the second control signal is used for determining a voltage reference value according to the reactive power setting, controlling the voltage output target amplitude of the virtual synchronous machine according to the voltage reference value, and eliminating the reactive-voltage sagging phenomenon of the virtual synchronous machine in the running process.
In a third aspect, embodiments of the present application provide a computer apparatus comprising a memory, a processor and computer readable instructions stored in the memory and executable on the processor, when executing the computer readable instructions, performing part or all of the steps as described in any of the methods of the first aspect.
In a fourth aspect, embodiments of the present application provide a computer-readable storage medium storing a computer program for electronic data exchange, the computer program comprising execution instructions for performing some or all of the steps described in any of the methods of the first aspect.
In a fifth aspect, embodiments of the present application provide a computer program product, wherein the computer program product comprises a computer program operable to cause a computer to perform some or all of the steps described in any of the methods of the first aspect of the embodiments of the present application. The computer program product may be a software installation package.
By implementing the embodiment of the application, the virtual synchronous machine firstly determines an active power setting and a reactive power setting according to the connection relation between the virtual synchronous machine and a public power grid, wherein the active power setting refers to the input power in the active power control flow of the virtual synchronous machine, and the reactive power setting refers to the input power in the reactive power control flow of the virtual synchronous machine; then, according to the active power, an angle reference value is given and determined, and according to the angle reference value, a first control signal of the virtual synchronous machine voltage output target frequency is controlled, wherein the first control signal is used for eliminating the active-frequency sagging phenomenon of the virtual synchronous machine in the running process; and meanwhile, a voltage reference value is determined according to reactive power setting, a second control signal of a target amplitude is output by the voltage of the virtual synchronous machine is controlled according to the voltage reference value, and the second control signal is used for eliminating reactive power-voltage sagging phenomenon of the virtual synchronous machine in the running process. The frequency and the amplitude of the output voltage of the virtual synchronous machine can be adjusted through the angle reference value and the voltage reference value by determining the angle reference value according to the active power setting and the voltage reference value according to the reactive power setting, so that the frequency offset and the voltage offset are eliminated, and the running stability of the virtual synchronous machine is improved.
Drawings
In order to more clearly describe the embodiments of the present application or the technical solutions in the background art, the following description will describe the drawings that are required to be used in the embodiments of the present application or the background art.
FIG. 1 is a flow chart of a virtual synchronous machine control method based on power selection and voltage feedback according to an embodiment of the present application;
FIG. 2 is a control block diagram of a virtual synchronous machine based on power selection and voltage feedback according to an embodiment of the present application;
FIG. 3 is a control block diagram of a reactive-voltage control loop of a virtual synchronous machine provided by an embodiment of the present application;
FIG. 4 is a control block diagram of an active-frequency control loop of a virtual synchronous machine provided by an embodiment of the present application;
fig. 5 is a schematic structural diagram of a virtual synchronous machine control device according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
The terms first, second, third and the like in the description and in the claims and in the drawings are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
The key concepts and features of the embodiments of the present application are explained below.
(1) Virtual synchronous machine: the virtual synchronous machine is a power electronic technology based on a micro-grid technology, and is an inverter with damping characteristics of a synchronous motor.
(2) Active-frequency droop: as the virtual synchronous machine active power increases, the frequency of the motor decreases and vice versa.
(3) Reactive-voltage sag: when the virtual synchronous machine reactive power increases, the voltage will be smaller and vice versa.
(4) PI: PI regulation is a linear control, P represents proportion, I represents integral, it forms control deviation according to given value and actual output value, the proportion and integral of deviation form control quantity by linear combination, and control the controlled object. PI regulation can react to deviations in the system in proportion, and as soon as a deviation occurs in the system, the proportional regulation produces a regulation effect to reduce the deviation.
In order to improve the average fluidity and realize the decoupling of active and reactive control during the parallel operation, the current general virtual synchronous machine operation control generally introduces virtual impedance (Rvsg+jXvsg) into a load control loop, and on the synchronous machine output control, the power is controlled by mechanical torque, the reactive power is controlled by an excitation system, and the two are independently operated. However, due to the voltage drop caused by the virtual impedance, the problems of active-frequency sagging and reactive-voltage sagging in the traditional virtual synchronous machine control method are difficult to avoid, the output voltage is inconsistent with the actual given voltage when the off-grid belt is in load operation, and damage to load equipment can be caused when the output voltage is too low.
In view of the above problems, an embodiment of the present application provides a virtual synchronous machine control method based on power selection and voltage feedback, which is applied to an energy storage virtual synchronous machine used by an energy storage system during grid connection or off-grid, and the method includes:
determining an active power setting and a reactive power setting according to the connection relation between the virtual synchronous machine and a public power grid, wherein the active power setting refers to input power in an active power control flow of the virtual synchronous machine, and the reactive power setting refers to input power in a reactive power control flow of the virtual synchronous machine; according to the active power, a given and determined angle reference value is used for controlling a first control signal of the virtual synchronous machine voltage output target frequency according to the angle reference value, wherein the first control signal is used for eliminating the active-frequency sagging phenomenon of the virtual synchronous machine in the running process; and according to the reactive power given and determined voltage reference value, controlling a second control signal of the voltage output target amplitude of the virtual synchronous machine according to the voltage reference value, wherein the second control signal is used for eliminating the reactive power-voltage sagging phenomenon of the virtual synchronous machine in the running process. The frequency and the amplitude of the output voltage of the virtual synchronous machine can be adjusted through the angle reference value and the voltage reference value by determining the angle reference value according to the active power setting and the voltage reference value according to the reactive power setting, so that the frequency offset and the voltage offset are eliminated, and the running stability of the virtual synchronous machine is improved.
In a possible implementation manner, referring to fig. 1, fig. 1 is a flowchart of a method for controlling a virtual synchronous machine based on power selection and voltage feedback according to an embodiment of the present application, as shown in fig. 1, the method for controlling a virtual synchronous machine based on power selection and voltage feedback includes the following steps:
s101, determining an active power setting and a reactive power setting according to the connection relation between the virtual synchronous machine and a public power grid;
s102, setting and determining an angle reference value according to the active power, and controlling a first control signal of the virtual synchronous machine voltage output target frequency according to the angle reference value;
and S103, determining a voltage reference value according to the reactive power, and controlling the virtual synchronous machine voltage to output a second control signal of a target amplitude according to the voltage reference value.
The connection relation between the virtual synchronous machine and the public power grid comprises grid connection of the virtual synchronous machine and the public power grid, grid disconnection of the virtual synchronous machine and the public power grid and switching from grid connection to grid disconnection of the virtual synchronous machine and the public power grid.
The active power setting refers to input power in an active power control flow of the virtual synchronous machine, and the reactive power setting refers to input power in a reactive power control flow of the virtual synchronous machine.
The angle reference value is used for frequency modulation of the subsequent virtual synchronous machine, and the voltage reference value is used for voltage regulation of the subsequent virtual synchronous machine.
The virtual synchronous machine control comprises an active control loop and a reactive control loop, wherein the control loop for determining an angle reference value according to the active power setting is the active control loop, and the control loop for determining a voltage reference value according to the reactive power setting is the reactive control loop.
The first control signal is used for eliminating active-frequency sagging phenomenon of the virtual synchronous machine in the running process, and the second control signal is used for eliminating reactive-voltage sagging phenomenon of the virtual synchronous machine in the running process.
It can be seen that, in this example, by determining the angle reference value according to the active power setting and determining the voltage reference value according to the reactive power setting, the frequency and amplitude of the output voltage of the virtual synchronous machine can be adjusted by the angle reference value and the voltage reference value, so that the frequency offset and the voltage offset are eliminated, and the running stability of the virtual synchronous machine is improved.
In a possible implementation manner, in step S101, the determining an active power setting and a reactive power setting according to a connection relationship between the virtual synchronous machine and a public power grid includes: judging whether the connection relation between the virtual synchronous machine and the public power grid is off-grid or the connection relation is switched to off-grid; if the connection relation between the virtual synchronous machine and the public power grid is judged to be off-grid or the connection relation is judged to be switched to be off-grid, the active power is given as load active power, and the reactive power is given as load reactive power; and if the connection relation between the virtual synchronous machine and the public power grid is judged to be grid connection, the active power is given as grid connection active power, and the reactive power is given as grid connection reactive power.
The active power setting of the virtual synchronous machine can be selected from grid-connected active power and load active power, and the reactive power setting of the virtual synchronous machine can be selected from grid-connected reactive power and load reactive power.
The control of the virtual synchronous machine is divided into an active control flow and a reactive control flow, wherein the active control flow is used for frequency modulation of the subsequent virtual synchronous machine, and the reactive control flow is used for voltage regulation of the subsequent virtual synchronous machine.
Therefore, in the example, the active power input and the reactive power input of the control flow of the virtual synchronous machine are determined according to the connection relation between the virtual synchronous machine and the public power grid, so that the virtual synchronous machine can better perform subsequent frequency modulation and voltage regulation according to the fluctuation condition of the power grid, and the working stability of the virtual synchronous machine is ensured.
In a possible implementation manner, in step S102, the determining an angle reference value according to the active power setting includes: acquiring a first difference value between the active power setting and active power feedback, wherein the active power setting is an actual value of the virtual synchronous machine active power setting; determining damping power according to the first difference value, the damping coefficient and the inertia coefficient; and determining an angle reference value according to the damping power, the first difference value and the rated angular frequency.
Wherein the damping power and the angle reference value are expressed as follows:
wherein the first control signal for controlling the virtual synchronous machine voltage output target frequency according to the angle reference value includes: the first control signal is used for taking the angle reference value as the frequency of the virtual synchronous machine voltage output to realize frequency modulation so as to eliminate the phenomenon of active-frequency sagging.
Referring to fig. 2, fig. 2 is a control block diagram of a virtual synchronous machine based on power selection and voltage feedback according to an embodiment of the present application, as shown in fig. 2,P Load for the active power of the load,P ref for the grid-tied active power,θ ref as a result of the angle reference value,P refAct for a given of the active power,P fb in order to use the power feedback for work,P damp for the said damping power to be sufficient,ω base for the nominal angular frequency omega ref For the angular frequency reference value in question,Jsas a function of the coefficient of inertia of the said mass,sand D is the damping coefficient, and is used for representing time domain integration in the frequency domain.
Illustratively, when the connection relationship of the virtual synchronous machine and the public power grid is grid connection, the active power is givenP refAct Given for active powerP ref Active power at this timeP refAct Given subtracted power feedbackP fb Obtaining a first difference value, wherein the first difference value passes through an inertia coefficient JsAnd the damping coefficient D obtains damping powerP damp In particular damping powerP damp Equal to the product of the first difference and the damping coefficient divided by the inertia coefficientJsSum of damping coefficient D and damping powerP damp Dividing by nominal angular frequencyω base Obtaining the angular frequency difference deltaωAngular frequency difference deltaωFor the frequency value which needs to be changed in the working process of the virtual synchronous machine, finally, the angular frequency difference delta is calculatedωAnd rated angular frequencyω base Sum of (2) divided bysPerforming time domain integration to obtain a value of the virtual synchronous machine, namely an angle reference value, which needs frequency modulationθ ref 。
Wherein,θ ref the output of (2) is in fact the frequency of the control voltage outputWhen the virtual synchronous machine is off-grid, the load active power is used as the output, so that the frequency output precision is higher, and the normal operation of the load is facilitated when the virtual synchronous machine is off-grid.
It can be seen that, in this example, by setting the active power and controlling the active control loop of the block diagram of the virtual synchronous machine, a value that the virtual synchronous machine needs to tune, that is, an angle reference value, can be obtained, which is beneficial for the virtual synchronous machine to tune according to the angle reference value, so as to eliminate the active-frequency sagging phenomenon.
In a possible implementation manner, the determining a voltage reference value according to the reactive power setting includes: obtaining a second difference value between a given value of the module voltage and feedback of the module voltage; obtaining a first voltage feedback value from the second difference through PI; obtaining a third sum value of the reactive power given value and the first voltage feedback value, wherein the third sum value is an actual value of the reactive power given value of the virtual synchronous machine; acquiring a fourth difference value between the third sum value and the reactive power feedback; obtaining a second voltage feedback value from the fourth difference value through PI; determining a voltage reference value according to the second voltage feedback value, the rated voltage, the module value current feedback, the virtual impedance and the low-pass filter, wherein the virtual impedance is the sum of the virtual resistance and the virtual inductance of the virtual synchronous machine, the product of the virtual impedance and the module value current feedback passes through the low-pass filter and then outputs voltage feedforward, and the voltage feedforward is used for ensuring the working voltage stability of the virtual synchronous machine when the power grid voltage fluctuates;
The expression of the voltage reference value is as follows:
wherein the second control signal for controlling the virtual synchronous machine voltage output target amplitude according to the voltage reference value includes: the second control signal is used for taking the voltage reference value as the amplitude of the voltage output of the virtual synchronous machine to realize voltage regulation so as to eliminate the reactive power-voltage sag phenomenon.
Wherein the method comprises the steps ofReferring to fig. 2, fig. 2 is a control block diagram of a virtual synchronous machine based on power selection and voltage feedback according to an embodiment of the present application, as shown in fig. 2,Q Load for the reactive power of the load in question,Q ref given the reactive power of the grid connection,V ref as a result of the voltage reference value,V base for the said voltage rating to be given,V m_ref for a given value of said modulus voltage,V m_fb for the feedback of the modulus voltage,Q refAct the virtual synchronous machine reactive power is given an actual value,Q fb for the reactive power feedback,k QP andk Qi in the form of a PI, the phase difference is,sfor representing a time-domain integration in the frequency domain,Ifor the feedback of the current to the module,R vsg for the purpose of the virtual resistance,X vsg for the purpose of the virtual inductance described above,jis imaginary unit, 1/(1 +)Ts) Is the low pass filter.
Illustratively, when the connection of the virtual synchronous machine to the utility grid is off-grid, the reactive power is loadedQ Load Given reactive power Q ref At this time, the modulus voltage is givenV m_ref Subtracting the modulus voltage feedbackV m_fb Obtaining a second difference value, obtaining a first voltage feedback value by the second difference value through PI, and setting reactive powerQ ref Adding the first voltage feedback value to obtain a third sum value, wherein the third sum value is an actual value given by reactive power of the virtual synchronous machine, and subtracting the reactive power feedback from the third sum valueQ fb Obtaining a fourth difference value, obtaining a second voltage feedback value through PI (proportion integration) of the fourth difference value, and finally obtaining a rated voltage according to the second voltage feedback valueV base Feedback of analog currentIVirtual impedanceR vsg +jX vsg And low pass filter 1/(1 +)Ts) Determining a voltage reference valueV ref Specifically, the voltage reference value is equal to the rated voltage plus the second voltage feedback value, then the product of the module current feedback and the virtual impedance is subtracted, and finally the value of the product of the module current feedback and the virtual impedance after passing through the low-pass filter is added.
Wherein,V ref the output of (2) is the output amplitude of the control voltage, and the general virtual synchronous machine control voltage output formula is as follows:
it can be seen that if Δv=0, it is due to the virtual impedanceR vsg +jX vsg ) Is the presence of (2)V ref Will be smaller thanV base While the scheme is given by reactive powerQ refAct =Q Load And adding a voltage loop of the voltage module value of the power grid so as to adjust the delta V, so as to improve the control precision of the voltage module value.
Referring to fig. 3, fig. 3 is a control block diagram of a reactive-voltage control loop of a virtual synchronous machine, as shown in fig. 3, a structure in a dashed line box a is a grid voltage value voltage loop added in a reactive outer loop, when the virtual synchronous machine and a public grid are in grid-connected operation, the grid voltage value voltage loop output is 0, and at this time, the grid voltage value outer loop output is 0, which is actually that the output of the reactive outer loop is completely determined by reactive power, so that the virtual synchronous machine has better reactive control characteristics during grid-connected operation.
When the grid is in off-grid operation, the grid voltage value voltage loop is overlapped on the reactive power set through the output of the PI regulator by the difference between the grid voltage value set and the grid voltage value feedback, the PI regulator can be modified into a pure proportion regulator, and the PI regulator is favorable for ensuring the accuracy of reactive power control.
It can be seen that, in this example, the value that the virtual synchronous machine needs to regulate, that is, the voltage reference value, can be obtained by setting the reactive power and controlling the reactive control loop of the block diagram of the virtual synchronous machine, so that the virtual synchronous machine can regulate the voltage according to the voltage reference value, and the reactive-voltage sag phenomenon can be eliminated.
In a possible implementation manner, please refer to fig. 3 again, a third voltage feedback value is obtained after the product of the virtual impedance and the feedback of the modulus current passes through the low-pass filter, and the low-pass filter reduces the third voltage feedback value by changing the cut-off frequency, so that the cut-off frequency is modified to reduce the third voltage feedback value to 0 when the virtual synchronous machine is in grid-connected operation, and unstable power grid caused by excessive reactive power generated when the power grid voltage fluctuates is prevented.
The structure in the dashed box B in fig. 3 is a voltage feedback link added to the reactive outer ring, and a voltage value obtained by multiplying the analog current feedback and the virtual impedance can be used as a correction value, where the correction value is used to compensate the voltage drop generated by the virtual impedance in advance.
Wherein, the voltage value obtained by multiplying the virtual impedance and the analog current feedback is passed through an LPF low-pass filter to obtain virtual impedance voltage feedforward, and the voltage feedforward is DeltaV FF When the feedforward coefficient is reduced, the cut-off frequency of the LPF low-pass filter changes, Δv FF The feedforward coefficient is reduced in proportion to the reduced amplitude, and the feedforward coefficient is 0, which is equivalent to the elimination of the virtual impedance voltage feedforward function. When the virtual synchronous machine and the public power grid are in grid-connected operation, the feedforward coefficient can be modified to be 0, the feedforward function of virtual impedance voltage can be canceled, unstable power grid caused by excessive reactive power when power grid voltage fluctuates can be prevented, and when loads are cut off, the dynamic response of voltage can be accelerated by reducing the feedforward coefficient.
It can be seen that, in this example, by adding a voltage feedback link to the reactive control loop of the virtual synchronous machine, the voltage drop generated due to the virtual impedance can be compensated, and meanwhile, the voltage feedforward function can be realized through the low-pass filter, so as to ensure the stability of the virtual synchronous machine.
In a possible implementation manner, referring to fig. 4, fig. 4 is a control block diagram of an active-frequency control loop of a virtual synchronous machine according to an embodiment of the present application, as shown in fig. 4, after determining damping power according to the first difference, damping coefficient and inertia coefficient, the method further includes: and adding a limiting link.
The amplitude limiting link refers to root opening processing of the damping power.
The structure in the dashed box of fig. 4 is an added clipping element, which is used to limit the active deviation.
It can be seen that in this example, the accuracy of the virtual synchronous machine control flow can be improved by adding a clipping link to the active control loop of the virtual synchronous machine to limit the active deviation.
Referring to fig. 5, fig. 5 is a schematic structural diagram of a virtual synchronous machine control device according to an embodiment of the present application, and as shown in fig. 5, a virtual synchronous machine control device 500 includes:
The power selection module 501 is configured to determine an active power setting and a reactive power setting according to a connection relationship between the virtual synchronous machine and a public power grid;
the parameter determining module 502 is configured to perform multiple processing on the active power setting to obtain an angle reference value, where the angle reference value is used to control a frequency of the virtual synchronous machine voltage output so as to eliminate an active-frequency sagging phenomenon in an operation process of the virtual synchronous machine; and the voltage reference value is used for controlling the amplitude of the voltage output of the virtual synchronous machine so as to eliminate the reactive power-voltage sagging phenomenon in the running process of the virtual synchronous machine.
Referring to fig. 6, fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application, where, as shown in fig. 6, the computer device includes a processor, a memory, and a communication interface, and the processor, the memory, and the communication interface are connected to each other and complete communication work therebetween;
the memory stores executable program codes, and the communication interface is used for wireless communication;
the processor, when executing the computer readable instructions, performs some or all of the steps of any of the virtual synchronous machine control methods based on power selection and voltage feedback as set forth in the method examples above.
The processor may include one or more processing cores. The processor uses various interfaces and lines to connect various portions of the overall electronic device, perform various functions of the electronic device, and process data by executing or executing instructions, programs, code sets, or instruction sets stored in memory, and invoking data stored in memory. Alternatively, the processor may be implemented in hardware in at least one of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), programmable logic array (ProgrammableLogic Array, PLA). The processor may integrate one or a combination of several of a central processing unit (CentralProcessing Unit, CPU), an image processor (Graphics Processing Unit, GPU), and a modem etc. It will be appreciated that the modem may not be integrated into the processor and may be implemented solely by a single communication chip.
The Memory may include random access Memory (Random Access Memory, RAM) or Read-Only Memory (ROM). The memory may be used to store instructions, programs, code sets, or instruction sets. The memory may include a stored program area and a stored data area, wherein the stored program area may store instructions for implementing an operating system, instructions for implementing at least one function (such as a touch function, a sound playing function, an image playing function, etc.), instructions for implementing examples of the respective methods described above, and the like. The storage data area may also store data created by the electronic device in use, etc.
It will be appreciated that the electronic device may include more or fewer structural elements than those described in the above structural block diagrams, including, for example, a power module, physical key, wiFi (Wireless Fidelity ) module, speaker, bluetooth module, sensor, etc., without limitation.
The present application provides a computer readable storage medium storing a computer program for electronic data exchange, the computer program comprising execution instructions for performing part or all of the steps of any one of the virtual synchronous machine control methods based on power selection and voltage feedback as set forth in the method examples above.
The present application also provides a computer program product comprising a non-transitory computer readable storage medium storing a computer program operable to cause a computer to perform part or all of the steps of any one of the virtual synchronous machine control methods based on power selection and voltage feedback as described in the method examples above. The computer program product may be a software installation package.
It should be noted that, for simplicity of description, any of the foregoing examples of the virtual synchronous machine control method based on power selection and voltage feedback are described as a series of combinations of actions, but those skilled in the art should appreciate that the present application is not limited by the order of actions described, as some steps may be performed in other order or simultaneously according to the present application. Further, it should be understood by those skilled in the art that the examples described in the specification are preferred examples and that the actions involved are not necessarily required for the present application.
Although the application is described herein in connection with various examples, other variations to the disclosed examples can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the figures, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Those of ordinary skill in the art will appreciate that all or a portion of the steps in any of the various examples of virtual synchronous machine control methods based on power selection and voltage feedback described above may be accomplished by a program that instructs associated hardware, the program may be stored in a computer readable memory, the memory may comprise: flash disk, read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), magnetic disk or optical disk.
The above description of the present application is provided in detail, and specific examples are applied to illustrate the principles and embodiments of a virtual synchronous machine control method and apparatus based on power selection and voltage feedback, where the above description is only for helping to understand the method and core idea of the present application; meanwhile, according to the idea of the virtual synchronous machine control method and device based on power selection and voltage feedback of the present application, the specific embodiments and application ranges are changed, and the present application is not limited to the above description.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, hardware products, and computer program products according to the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be appreciated that any product of the processing method of the flowchart described by way of example of a virtual synchronous machine control method based on power selection and voltage feedback, as well as the terminals of the flowchart and the computer program product described above, which is controlled or configured to perform the method of the present application, falls within the scope of the related products described in the present application.
It will be apparent to those skilled in the art that various modifications and variations can be made in the method and apparatus for controlling a virtual synchronous machine based on power selection and voltage feedback provided by the present application without departing from the spirit and scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (10)
1. The virtual synchronous machine control method based on power selection and voltage feedback is applied to a virtual synchronous machine used by an energy storage system during grid connection or grid disconnection, and is characterized by comprising the following steps:
determining an active power setting and a reactive power setting according to the connection relation between the virtual synchronous machine and a public power grid, wherein the active power setting refers to input power in an active power control flow of the virtual synchronous machine, and the reactive power setting refers to input power in a reactive power control flow of the virtual synchronous machine;
according to the active power, a given and determined angle reference value is used for controlling a first control signal of the virtual synchronous machine voltage output target frequency according to the angle reference value, wherein the first control signal is used for eliminating the active-frequency sagging phenomenon of the virtual synchronous machine in the running process;
and according to the reactive power given and determined voltage reference value, controlling a second control signal of the voltage output target amplitude of the virtual synchronous machine according to the voltage reference value, wherein the second control signal is used for eliminating the reactive power-voltage sagging phenomenon of the virtual synchronous machine in the running process.
2. The method of claim 1, wherein determining the active power setting and the reactive power setting based on the connection of the virtual synchronous machine to the utility grid comprises:
Judging whether the connection relation between the virtual synchronous machine and the public power grid is off-grid or the connection relation is switched to off-grid;
if the connection relation between the virtual synchronous machine and the public power grid is judged to be off-grid or the connection relation is judged to be switched to be off-grid, the active power is given as load active power, and the reactive power is given as load reactive power;
and if the connection relation between the virtual synchronous machine and the public power grid is judged to be grid connection, the active power is given as grid connection active power, and the reactive power is given as grid connection reactive power.
3. The method of claim 2, wherein said determining an angular reference value based on said active power setting comprises:
acquiring a first difference value between the active power setting and active power feedback, wherein the active power setting is an actual value of the virtual synchronous machine active power setting;
determining damping power according to the first difference value, the damping coefficient and the inertia coefficient;
determining an angle reference value according to the damping power, the first difference value and the rated angular frequency;
the damping power and the angle reference value are expressed as follows:
wherein,θ ref as a result of the angle reference value,P refAct for a given of the active power, P fb In order to use the power feedback for work,P damp for the said damping power to be sufficient,ω base for the said nominal angular frequency of the said angle,Jsas a function of the coefficient of inertia of the said mass,sfor representing a time-domain integration in the frequency domain,Dis the damping coefficient.
4. A method according to claim 3, wherein said first control signal for controlling said virtual synchro-machine voltage output target frequency in accordance with said angle reference value comprises:
the first control signal is used for taking the angle reference value as the frequency of the virtual synchronous machine voltage output to realize frequency modulation so as to eliminate the phenomenon of active-frequency sagging.
5. The method of claim 2, wherein said determining a voltage reference from said reactive power setting comprises:
obtaining a second difference value between the given value of the module voltage and feedback of the module voltage;
obtaining a first voltage feedback value from the second difference through PI;
obtaining a third sum value of the reactive power given value and the first voltage feedback value, wherein the third sum value is an actual value of the reactive power given value of the virtual synchronous machine;
acquiring a fourth difference value between the third sum value and the reactive power feedback;
obtaining a second voltage feedback value from the fourth difference value through PI;
Determining a voltage reference value according to the second voltage feedback value, the rated voltage, the module value current feedback, the virtual impedance and the low-pass filter, wherein the virtual impedance is the sum of the virtual resistance and the virtual inductance of the virtual synchronous machine, the product of the virtual impedance and the module value current feedback passes through the low-pass filter and then outputs voltage feedforward, and the voltage feedforward is used for ensuring the working voltage stability of the virtual synchronous machine when the power grid voltage fluctuates;
the expression of the voltage reference value is as follows:
wherein,V ref as a result of the voltage reference value,V base for the said voltage rating to be given,Q refAct the virtual synchronous machine reactive power is given an actual value,Q fb for the reactive power feedback,k QP andk Qi in the form of a PI, the phase difference is,sfor representing a time-domain integration in the frequency domain,Ifor the feedback of the current to the module,R vsg for the purpose of the virtual resistance,X vsg for the purpose of the virtual inductance described above,jis imaginary unit, 1/(1 +)Ts) Is the low pass filter.
6. The method of claim 5, wherein the controlling the second control signal of the virtual synchronous machine voltage output target amplitude according to the voltage reference value comprises:
the second control signal is used for taking the voltage reference value as the amplitude of the voltage output of the virtual synchronous machine to realize voltage regulation so as to eliminate the reactive power-voltage sag phenomenon.
7. The method of claim 6, wherein a third voltage feedback value is obtained by the product of the virtual impedance and the modulus current feedback through the low-pass filter, and the low-pass filter reduces the third voltage feedback value by changing a cutoff frequency, so that the third voltage feedback value is reduced to 0 by modifying the cutoff frequency when the virtual synchronous machine is in grid-connected operation, and the unstable power grid caused by excessive reactive power when the power grid voltage fluctuates is prevented.
8. The method of any of claims 3-4, wherein after said determining damping power from said first difference, damping coefficient, and inertia coefficient, the method further comprises:
and adding an amplitude limiting link, wherein the amplitude limiting link refers to the process of opening a root number on the damping power and is used for limiting the active deviation.
9. A virtual synchronous machine control device based on power selection and voltage feedback, comprising:
the power selection module is used for determining an active power given value and a reactive power given value according to the connection relation between the virtual synchronous machine and the public power grid;
the parameter determining module is used for determining an angle reference value according to the active power setting, controlling a first control signal of the virtual synchronous machine voltage output target frequency according to the angle reference value, wherein the first control signal is used for eliminating the active-frequency sagging phenomenon of the virtual synchronous machine in the running process; and the second control signal is used for determining a voltage reference value according to the reactive power setting, controlling the voltage output target amplitude of the virtual synchronous machine according to the voltage reference value, and eliminating the reactive-voltage sagging phenomenon of the virtual synchronous machine in the running process.
10. A computer device comprising a memory, a processor and computer readable instructions stored in the memory and executable on the processor, the processor executing the computer readable instructions to perform the steps of the virtual synchro machine control method based on power selection and voltage feedback as claimed in any one of claims 1-8.
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