CN111628504B - Inverter modeling method containing amplitude limiter and related device - Google Patents

Inverter modeling method containing amplitude limiter and related device Download PDF

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CN111628504B
CN111628504B CN202010597334.7A CN202010597334A CN111628504B CN 111628504 B CN111628504 B CN 111628504B CN 202010597334 A CN202010597334 A CN 202010597334A CN 111628504 B CN111628504 B CN 111628504B
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limiter
saturation
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inverter
control loop
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CN111628504A (en
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谈赢杰
徐敏
郭祚刚
雷金勇
袁智勇
叶琳浩
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China South Power Grid International Co ltd
China Southern Power Grid Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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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
    • 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
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Abstract

The application discloses a method and a related device for modeling an inverter comprising a limiter, wherein the method comprises the following steps: establishing a differential equation model of a voltage and current control loop in the inverter, wherein the differential equation model comprises a piecewise function of a saturation amplitude limiter; determining an upper boundary and a lower boundary and a critical saturation point of the saturation amplitude limiter based on a piecewise function of the saturation amplitude limiter; performing continuous function conversion on the piecewise function based on the Sigmoid function, and configuring parameters in the continuous function obtained by conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain the continuous function of the saturation amplitude limiter; the continuous function of the saturation amplitude limiter replaces the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model, so that the technical problem that the inverter model is required to be continuous and cannot be applied to an inverter comprising the amplitude limiter in the prior art when the inverter modeling is carried out through the differential equation is solved.

Description

Inverter modeling method containing amplitude limiter and related device
Technical Field
The present disclosure relates to the field of power equipment modeling technologies, and in particular, to a method and a related apparatus for modeling an inverter including a limiter.
Background
Due to the influence of the fossil energy crisis, research and utilization of new energy sources have been started. An inverter, which is an important device for utilizing new energy, is an important device that can convert renewable energy such as wind power and light energy into electric energy and transmit the electric energy to a user or a public power grid as one of core devices of a microgrid, and has attracted much attention in recent years.
The microgrid is a small-scale system compared to a conventional grid, but it also has the fundamental characteristics of the operation of an electric power system. Inverters distributed in the microgrid, namely distributed micro sources, can provide voltage and frequency support for normal operation of the microgrid, and can also directly provide power for local loads. The distributed micro-source has the advantages of complex control mode, variable control structure and various control targets, so that the inverter has strong nonlinear characteristics. In order to research the operation characteristics and parameter change rules of the inverter, the inverter needs to be modeled and analyzed. In the prior art, the inverter is usually modeled by differential equations, but the method requires the continuity of an inverter type model and cannot be applied to the inverter comprising a limiter.
Disclosure of Invention
The application provides an inverter modeling method comprising a limiter and a related device, which are used for solving the technical problems that in the prior art, inverter modeling is carried out through a differential equation, an inverter model is required to have continuity, and the inverter modeling method cannot be applied to an inverter comprising the limiter.
In view of the above, a first aspect of the present application provides an inverter modeling method including a limiter, including:
establishing a differential equation model of a voltage and current control loop in the inverter, wherein the differential equation model comprises a piecewise function of a saturation amplitude limiter;
determining an upper and lower bound and a critical saturation point of the saturation limiter based on a piecewise function of the saturation limiter;
performing continuous function conversion on the piecewise function based on a Sigmoid function, and configuring parameters in the continuous function obtained through conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain a continuous function of the saturation amplitude limiter;
and replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
Optionally, the differential equation model is:
Figure GDA0003247981880000021
wherein, UrefReference internal potential, U, obtained for the reactive control loopoutIs the voltage on the filter capacitor, kvp、kviRespectively a proportional regulation coefficient and an integral regulation coefficient of a voltage control loop PI controller,
Figure GDA0003247981880000022
is composed of
Figure GDA0003247981880000023
The value of the integrated value is then,
Figure GDA0003247981880000024
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxTo saturate the amplitude of the limiting current value, IoutIs the filter inductor current, f (I)ref) Is a piecewise function of a limiter, kip、kiiRespectively is a proportional regulation coefficient and an integral regulation coefficient of a current control loop PI controller, and gamma is
Figure GDA0003247981880000025
The integrated value, E, is the voltage amplitude of the modulated PWM wave.
Optionally, the continuous function of the saturation limiter is:
Figure GDA0003247981880000026
wherein k and e are constants.
A second aspect of the present application provides an inverter modeling apparatus including a limiter, including:
the model establishing unit is used for establishing a differential equation model of a voltage and current control loop in the inverter, and the differential equation model comprises a piecewise function of a saturation amplitude limiter;
a parameter determining unit, configured to determine an upper and lower boundary and a critical saturation point of the saturation limiter based on a piecewise function of the saturation limiter;
the conversion unit is used for carrying out continuous function conversion on the piecewise function based on a Sigmoid function, and configuring parameters in the continuous function obtained by conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain the continuous function of the saturation amplitude limiter;
and the replacing unit is used for replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
Optionally, the differential equation model is:
Figure GDA0003247981880000031
wherein, UrefReference internal potential, U, obtained for the reactive control loopoutIs the voltage on the filter capacitor, kvp、kviRespectively a proportional regulation coefficient and an integral regulation coefficient of a voltage control loop PI controller,
Figure GDA0003247981880000032
is composed of
Figure GDA0003247981880000033
The value of the integrated value is then,
Figure GDA0003247981880000034
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxIn order to saturate the clipping current value,Ioutis the filter inductor current, f (I)ref) Is a piecewise function of a limiter, kip、kiiRespectively is a proportional regulation coefficient and an integral regulation coefficient of a current control loop PI controller, and gamma is
Figure GDA0003247981880000036
The integrated value, E, is the voltage amplitude of the modulated PWM wave.
Optionally, the continuous function of the saturation limiter is:
Figure GDA0003247981880000035
wherein k and e are constants.
A third aspect of the present application provides an inverter modeling apparatus including a limiter, the apparatus including a processor and a memory;
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the inverter modeling method including a limiter according to any one of the first aspect according to instructions in the program code.
A fourth aspect of the present application provides a computer-readable storage medium for storing program code for executing the inverter modeling method including a limiter according to any one of the first aspects.
According to the technical scheme, the method has the following advantages:
the application provides an inverter modeling method comprising a limiter, which comprises the following steps: establishing a differential equation model of a voltage and current control loop in the inverter, wherein the differential equation model comprises a piecewise function of a saturation amplitude limiter; determining an upper boundary and a lower boundary and a critical saturation point of the saturation amplitude limiter based on a piecewise function of the saturation amplitude limiter; performing continuous function conversion on the piecewise function based on the Sigmoid function, and configuring parameters in the continuous function obtained by conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain the continuous function of the saturation amplitude limiter; and replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
The inverter modeling method comprises the steps of establishing a differential equation model of a voltage and current control loop of a piecewise function of a saturation amplitude limiter, carrying out continuous function conversion on the piecewise function of the amplitude limiter by introducing a Sigmoid function, configuring parameters in the continuous function obtained by conversion through the upper boundary and the lower boundary of the saturation amplitude limiter and the critical saturation point to obtain the continuous function of the saturation amplitude limiter, converting the piecewise function into the continuous function to avoid the problem that an unguided 'singular point' cannot exist in the differential equation model, and solving the problem of continuity of the inverter model, so that the technical problem that the inverter modeling is carried out through the differential equation in the prior art and the inverter model is required to have continuity and cannot be applied to an inverter comprising the amplitude limiter is solved.
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Fig. 1 is a schematic flowchart of a method for modeling an inverter including a limiter according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of an inverter modeling apparatus including a limiter according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a microgrid grid-connected inverter according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of an active power control loop of a microgrid grid-connected inverter according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of a reactive power control loop of a microgrid grid-connected inverter according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a voltage-current control loop of a microgrid grid-connected inverter according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
To facilitate understanding, referring to fig. 1, the present application provides an embodiment of an inverter modeling method including a limiter, including:
step 101, establishing a differential equation model of a voltage and current control loop in the inverter.
It should be noted that, when modeling and analyzing the inverter stability, the differential equation is a better analysis method, and the method can accurately describe the system operation state, and can also improve the system resolving speed by reducing order and simplifying, so that the differential equation model of the voltage current control loop in the inverter is established in the embodiment of the application, wherein the differential equation model includes the piecewise function of the saturation limiter.
Step 102, determining the upper and lower bounds and critical saturation points of the saturation limiter based on the piecewise function of the saturation limiter.
And 103, performing continuous function conversion on the piecewise function based on the Sigmoid function, and configuring parameters in the continuous function obtained through conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain the continuous function of the saturation amplitude limiter.
It should be noted that, under the unsaturated operating condition, the Sigmoid function output effect is close to 0, and under the saturated operating condition, the Sigmoid function output effect is close to 1, which indicates that the description of the actual situation can be realized by improving the Sigmoid function. When the controlled condition, namely the reference current is not saturated, the influence of the Sigmoid function on the system is approximately 0, the output current of the droop inverter is basically the same as the operation condition when the Sigmoid function is not adopted for description, and the system is in a normal operation state; when the controlled condition, namely the reference current is saturated, the Sigmoid function has an adjusting effect on the system, the reference current is limited at the position of the maximum reference current, at the moment, the droop is degraded to be a current source, and because the output value of the Sigmoid function is approximate to 1 when the current is saturated, the maximum reference current at the moment can be considered as a saturation limiting current value, so that the original discontinuous describing method of the piecewise function can be replaced by using the continuous Sigmoid function, the problem that an inconductive 'singular point' cannot exist in a differential equation model is avoided, and the problem that the system model is complex due to the piecewise function is also avoided.
And step 104, replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
It should be noted that the continuous function of the saturation limiter is replaced by the piecewise function of the saturation limiter, so as to obtain a continuous differential equation model.
The inverter modeling method comprising the amplitude limiter in the embodiment of the application establishes a differential equation model of a voltage and current control loop comprising a piecewise function of a saturation amplitude limiter, continuous function conversion is carried out on the piecewise function of the amplitude limiter by introducing a Sigmoid function, parameters in the continuous function obtained by conversion are configured through the upper boundary and the lower boundary of the saturation amplitude limiter and the critical saturation point to obtain the continuous function of the saturation amplitude limiter, and the problem that an unguided 'singular point' cannot exist in the differential equation model is solved by converting the piecewise function into the continuous function, so that the technical problem that the inverter model is required to have continuity when the inverter modeling is carried out through the differential equation in the prior art and cannot be applied to an inverter comprising the amplitude limiter is solved.
For the convenience of understanding, the embodiment of the present application provides a specific application example of an inverter modeling method including a limiter.
Taking a micro-grid-connected inverter as an example, please refer to fig. 3, the micro-grid connection adopts the circuit and the control structure shown in fig. 3, the voltage at the direct current side is matched with the modulated PWM wave signal through the switching tube on the bridge arm to generate the voltage at the internal potential at the alternating current side, the potential difference and the corresponding current are established between the midpoint of the bridge arm and the grid, and the current injects power to the grid through the LC filter and the grid-connected inductor at the output port. And the control link feeds back signals such as the measured capacitance voltage, the measured filter current, the measured grid-connected current and the like, so as to control the output power, the measured output voltage and the measured output current of the inverter, wherein the obtained control feedback signals are modulated PWM waves.
The power control loop structure of the inverter is shown in fig. 4 and 5, and as can be known from fig. 4 and 5, the controller converts the active power and reactive power signals output by the inverter by iteration into an inverter voltage rotation angular velocity and an internal potential amplitude signal. The control mode simulates the characteristics of speed regulation and voltage regulation droop of the traditional synchronous generator and has good dynamic property.
Ignoring the inverter modulation process, the voltage-current control loop structure of the inverter is shown in fig. 6, where UrefReference internal potential, Z, derived for the reactive control loopfIs the equivalent resistance of the filter inductor, IfIs a filter inductor current, IcFor current in filter capacitors, UoFor the voltage across the filter capacitor, UgFor the mains voltage, ZlineIs the line impedance. As can be seen from fig. 6, in order to prevent the overshoot of the control signal, the PI-link meaning limiter in the inverter control can reduce the abnormal operating state of the inverter. The addition of the amplitude limiter can relieve the influence of sudden change of controller parameters on control, prevent integral saturation and the like, but also bring certain stability problem, and the inverter added with the amplitude limiter can generate power angle instability phenomenon under the condition of accessing a weak power grid.
The method for analyzing the stability problem of the amplitude limiter at present comprises a small signal modeling method, a large signal modeling method, numerical simulation and the like, wherein the methods all depend on an accurate mathematical model, the modeling method which is depended by the methods is mainly a differential equation model, namely a quasi-steady state equation is established by utilizing the characteristics of components of a power system, wherein the small signal modeling method needs to be locally linearized at a specific operating point position according to the quasi-steady state differential equation of the system, a small signal analysis model is established, and the small disturbance problem of the system is analyzed. The large signal modeling method can be used for analyzing the stability of the inverter, and the method judges and obtains the conservative boundary of the energy function and the stability of the system according to the stability by establishing a system differential equation, but the method has the following problems: (1) the system order is too low to reflect the effect of the amplitude limiter on the system, and the existing transient stability analysis means mostly adopt a low-order system with strong conservative property and can only reflect the running characteristics of part of the system; (2) an order that is too high may reflect the system order, but is computationally complex, while an equation that uses a linear matrix optimization (LMI) method requires continuity in the system being modeled.
In summary, the quasi-steady-state modeling method that relies on for analyzing the stability of the inverter has certain limitations, and cannot be used for analyzing the inverter with the limiter. Through comparative analysis, it is found that when the existing quasi-steady-state modeling method is used for stability analysis, a system quasi-steady-state equation cannot contain an immutable singular point, and a commonly used amplitude limiting mode in a control structure of an inverter using an amplitude limiter is a piecewise function, taking a typical current saturation piecewise amplitude limiting function as an example, that is:
Figure GDA0003247981880000071
wherein the content of the first and second substances,
Figure GDA0003247981880000072
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxTo saturate the clipping current value, f (I)ref) For the piecewise function of the limiter, it can be seen from equation (1) that the reference output current of the system, although continuous, has a non-derivable singularity, i.e., Iref＝ImaxThe time-of-day operating point and the judgment condition of current saturation cannot use a continuous function expression, and in order to solve the problem, the embodiment of the application proposes that the Sigmoid-based function is adopted to carry out the piecewise functionAnd (4) converting a continuous function, wherein the expression of the Sigmoid function is as follows:
Figure GDA0003247981880000081
from the expression of the Sigmoid function, it can be known that when x approaches minus infinity, the output value of the Sigmoid function approaches 0, and similarly, when x approaches plus infinity, the output value of the Sigmoid function approaches 1, and the Sigmoid function is improved, and the current expression can obtain a better approximate result, and two improved Sigmoid functions are proposed in the embodiment of the present application:
Figure GDA0003247981880000082
Figure GDA0003247981880000083
wherein k is a constant, and when k is larger, the change process of s (x) is more approximate to the step function image, and the continuous current saturation piecewise limiting function, namely the continuous function of the saturation limiter, is obtained by combining the two improved Sigmoid functions:
Figure GDA0003247981880000084
wherein k is>0, configuring parameters in the continuous function obtained by conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter, wherein the k value is selected from the maximum current value ImaxIt is decided that the k value satisfies the condition: when the actual current value is satisfied at (I)max±20％Imax) Within the range of (3), the Sigmoid function output value is greater than 0.9, so that the Sigmoid function can approximately replace the piecewise function, that is, the k value satisfies:
Figure GDA0003247981880000085
the successive function conversion of the piecewise function is carried out by Sigmoid function, and the reference input current of the current control loop is converted into IrefThe related function expression can be used in the quasi-steady-state modeling of the system, and breaks through the limitations of stable point operation, infinite amplitude transformer and the like in the existing quasi-steady-state modeling method.
Before the Sigmoid function is applied, the differential equation model of the voltage and current control loop of the inverter system is as follows:
Figure GDA0003247981880000091
wherein, UrefReference internal potential, U, obtained for the reactive control loopoutIs the voltage on the filter capacitor, kvp、kviRespectively a proportional regulation coefficient and an integral regulation coefficient of a voltage control loop PI controller,
Figure GDA0003247981880000092
is composed of
Figure GDA0003247981880000093
The value of the integrated value is then,
Figure GDA0003247981880000094
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxTo saturate the amplitude of the limiting current value, IoutIs the filter inductor current, f (I)ref) Is a piecewise function of a limiter, kip、kiiRespectively is a proportional regulation coefficient and an integral regulation coefficient of a current control loop PI controller, and gamma is
Figure GDA0003247981880000095
The integrated value, E, is the voltage amplitude of the modulated PWM wave.
Due to the reference current IrefAt a current amplitude equal to ImaxIs a singular point at which the differential equation model is not derivable and at which the system is not able toThe stability analysis is performed nearby, the continuous function of the saturation limiter obtained by performing continuous function conversion on the piecewise function of the saturation limiter replaces the piecewise function to obtain a continuous differential equation model, the singularity problem is solved through the model, the model can be used for stability analysis, and the result obtained by analyzing through the model is close to the actual operation condition. Replacing the piecewise function with the continuous function of the saturation amplitude limiter obtained by performing continuous function conversion on the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model as follows:
Figure GDA0003247981880000096
for ease of understanding, referring to fig. 2, the present application provides an embodiment of an inverter modeling apparatus including a limiter, including:
and the model establishing unit is used for establishing a differential equation model of a voltage and current control loop in the inverter, and the differential equation model comprises a piecewise function of the saturation amplitude limiter.
And the parameter determining unit is used for determining the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter based on the piecewise function of the saturation amplitude limiter.
And the conversion unit is used for carrying out continuous function conversion on the piecewise function based on the Sigmoid function, and configuring parameters in the continuous function obtained by conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain the continuous function of the saturation amplitude limiter.
And the replacing unit is used for replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
As a further improvement, the differential equation model is:
Figure GDA0003247981880000101
wherein, UrefReference internal potential, U, obtained for the reactive control loopoutIs the voltage on the filter capacitor, kvp、kviRespectively a proportional regulation coefficient and an integral regulation coefficient of a voltage control loop PI controller,
Figure GDA0003247981880000102
is composed of
Figure GDA0003247981880000103
The value of the integrated value is then,
Figure GDA0003247981880000104
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxTo saturate the amplitude of the limiting current value, IoutIs the filter inductor current, f (I)ref) Is a piecewise function of a limiter, kip、kiiRespectively is a proportional regulation coefficient and an integral regulation coefficient of a current control loop PI controller, and gamma is
Figure GDA0003247981880000105
The integrated value, E, is the voltage amplitude of the modulated PWM wave.
As a further improvement, the continuous function of the saturation limiter is:
Figure GDA0003247981880000106
wherein k and e are constants.
The embodiment of the application also provides inverter modeling equipment comprising a limiter, wherein the equipment comprises a processor and a memory;
the memory is used for storing the program codes and transmitting the program codes to the processor;
the processor is configured to execute the inverter modeling method including the limiter in the aforementioned inverter modeling method including the limiter embodiment according to instructions in the program code.
Embodiments of the present application further provide a computer-readable storage medium for storing program codes for executing the inverter modeling method including a limiter in the foregoing inverter modeling method including a limiter.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for executing all or part of the steps of the method described in the embodiments of the present application through a computer device (which may be a personal computer, a server, or a network device). And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims (8)

1. A method of modeling an inverter including a limiter, comprising:
establishing a differential equation model of a voltage and current control loop in the inverter, wherein the differential equation model comprises a piecewise function of a saturation amplitude limiter;
determining an upper and lower bound and a critical saturation point of the saturation limiter based on a piecewise function of the saturation limiter;
performing continuous function conversion on the piecewise function based on a Sigmoid function, and configuring parameters in the continuous function obtained through conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain a continuous function of the saturation amplitude limiter;
and replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
2. The method of modeling an inverter including a limiter according to claim 1, wherein the differential equation model is:
Figure FDA0003247981870000011
wherein, UrefReference internal potential, U, obtained for the reactive control loopoutIs the voltage on the filter capacitor, kvp、kviRespectively a proportional regulation coefficient and an integral regulation coefficient of a voltage control loop PI controller,
Figure FDA0003247981870000012
is composed of
Figure FDA0003247981870000013
The value of the integrated value is then,
Figure FDA0003247981870000014
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxTo saturate the amplitude of the limiting current value, IoutIs the filter inductor current, f (I)ref) Is a piecewise function of a limiter, kip、kiiRespectively is a proportional regulation coefficient and an integral regulation coefficient of a current control loop PI controller, and gamma is
Figure FDA0003247981870000016
The integrated value, E, is the voltage amplitude of the modulated PWM wave.
3. The method of modeling an inverter including a limiter according to claim 2, wherein the continuous function of the saturation limiter is:
Figure FDA0003247981870000015
wherein k and e are constants.
4. An inverter modeling apparatus including a limiter, comprising:
the model establishing unit is used for establishing a differential equation model of a voltage and current control loop in the inverter, and the differential equation model comprises a piecewise function of a saturation amplitude limiter;
a parameter determining unit, configured to determine an upper and lower boundary and a critical saturation point of the saturation limiter based on a piecewise function of the saturation limiter;
the conversion unit is used for carrying out continuous function conversion on the piecewise function based on a Sigmoid function, and configuring parameters in the continuous function obtained by conversion through the upper and lower boundaries and the critical saturation point of the saturation amplitude limiter to obtain the continuous function of the saturation amplitude limiter;
and the replacing unit is used for replacing the continuous function of the saturation amplitude limiter with the piecewise function of the saturation amplitude limiter to obtain a continuous differential equation model.
5. The inverter modeling apparatus including a limiter according to claim 4, wherein the differential equation model is:
Figure FDA0003247981870000021
wherein, UrefReference internal potential, U, obtained for the reactive control loopoutIs the voltage on the filter capacitor, kvp、kviRespectively a proportional regulation coefficient and an integral regulation coefficient of a voltage control loop PI controller,
Figure FDA0003247981870000022
is composed of
Figure FDA0003247981870000023
The value of the integrated value is then,
Figure FDA0003247981870000024
is a reference current of a current control loop, IrefReference current, I, output for voltage control loopmaxTo saturate the amplitude of the limiting current value, IoutIs the filter inductor current, f (I)ref) Is a piecewise function of a limiter, kip、kiiRespectively is a proportional regulation coefficient and an integral regulation coefficient of a current control loop PI controller, and gamma is
Figure FDA0003247981870000025
The integrated value, E, is the voltage amplitude of the modulated PWM wave.
6. The inverter modeling apparatus including a limiter as in claim 5, wherein the continuous function of the saturation limiter is:
Figure FDA0003247981870000026
wherein k and e are constants.
7. An inverter modeling apparatus including a limiter, the apparatus comprising a processor and a memory;
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the inverter modeling method including a limiter according to any one of claims 1 to 3 according to instructions in the program code.
8. A computer-readable storage medium for storing program code for executing the inverter modeling method including a limiter according to any one of claims 1 to 3.
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