CN113346515A - Self-synchronizing voltage source control method and system based on continuous extended state observer - Google Patents

Self-synchronizing voltage source control method and system based on continuous extended state observer Download PDF

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CN113346515A
CN113346515A CN202110437571.1A CN202110437571A CN113346515A CN 113346515 A CN113346515 A CN 113346515A CN 202110437571 A CN202110437571 A CN 202110437571A CN 113346515 A CN113346515 A CN 113346515A
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extended state
state observer
continuous
function
disturbance
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池淑梅
吕志鹏
韩筛根
宋振浩
周珊
刘文龙
薛琳
刘峰
刘梦
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China Online Shanghai Energy Internet Research Institute Co ltd
Electric Power Research Institute of State Grid Shanghai Electric Power 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin

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Abstract

The invention discloses a self-synchronizing voltage source control method and a system based on a continuous extended state observer, which comprise the following steps: the extended state observer of the self-synchronous voltage source grid-connected device is improved, a piecewise function in the traditional extended state observer is changed into a continuous function, and a continuous extended state observer is obtained; and evaluating the load of the power grid system and the disturbance of the new energy power supply through the continuous extended state observer, and compensating the virtual torque of the virtual synchronous motor through the load and the disturbance of the new energy power supply obtained through evaluation, so that the influence of the disturbance on the power grid is eliminated, and the voltage and the frequency of the power grid are kept stable. The problem that the voltage and the frequency of a power grid vibrate under the disturbance of a new energy power supply and are not stable enough due to switching point conversion and gain mutation in the function feedback process of the traditional extended state observer is solved.

Description

Self-synchronizing voltage source control method and system based on continuous extended state observer
Technical Field
The application relates to the field of control of power electronic converters on the source side of a power distribution network or a micro power grid, in particular to a self-synchronizing voltage source control method based on a continuous extended state observer, and also relates to a self-synchronizing voltage source control system based on the continuous extended state observer.
Background
With the gradual increase of the permeability of new energy in an electric power system, a high-proportion new energy power distribution network and a micro-grid are gradually put into construction, but the inertia of the power grid is reduced due to the increase of the grid connection of distributed power sources, and the voltage and frequency fluctuation of the power grid is also aggravated due to the intermittency and the non-schedulability of the new energy. To solve the above problems, a self-synchronous voltage source control technique is proposed, but some problems such as oscillation and voltage threshold crossing still exist.
At present, a self-synchronous voltage source grid-connected technology is available, in the technology, an electromagnetic equation and a mechanical equation of a synchronous generator are applied to the design of a power electronic converter control strategy, inertia and damping are added in the traditional droop control, and under the control of the technology, a direct-current voltage source can show inertia characteristics and damping characteristics similar to those of the synchronous generator, so that the voltage and frequency of a power grid are effectively supported to be stable, and the power grid fault can be better responded. However, the new energy power supply fluctuates frequently, such as: photovoltaic and the like, the output power of which often changes along with the change of environmental factors, are easy to cause bus voltage oscillation, and when the fluctuation is large, the problem of voltage out-of-limit can be caused, which is not beneficial to the stable operation of a high-proportion new energy power system. The traditional function feedback process of the extended state observer has the problems of switching point conversion and gain mutation, so that the control process is likely to generate oscillation and is not stable enough.
Disclosure of Invention
In order to solve the above problem, the present application provides a self-synchronizing voltage source control method based on a continuous extended state observer, including:
the extended state observer of the self-synchronous voltage source grid-connected device is improved, a piecewise function in the traditional extended state observer is changed into a continuous function, and a continuous extended state observer is obtained;
and evaluating the load of the power grid system and the disturbance of the new energy power supply through the continuous extended state observer, and compensating the virtual torque of the virtual synchronous motor through the load and the disturbance of the new energy power supply obtained through evaluation, so that the influence of the disturbance on the power grid is eliminated, and the voltage and the frequency of the power grid are kept stable.
Preferably, the topology of the self-synchronizing voltage source grid-connected device adopts a three-phase full-bridge power electronic device.
Preferably, the step of converting the piecewise function in the conventional extended state observer into a continuous function comprises:
a piecewise function fal in the traditional extended state observer is improved through an arctangent function, and the piecewise function fal is changed into a continuous function fall.
The application also provides a self-synchronizing voltage source control system based on the continuous extended state observer, which comprises:
the continuous extended state observer obtaining module is used for improving an extended state observer of the self-synchronous voltage source grid-connected device, changing a piecewise function in the traditional extended state observer into a continuous function and obtaining a continuous extended state observer;
and the voltage and frequency stabilization module is used for evaluating the load of the power grid system and the disturbance of the new energy power supply through the continuous extended state observer, and compensating the virtual torque of the virtual synchronous motor through the load and the disturbance of the new energy power supply obtained through evaluation, so that the influence of the disturbance on the power grid is eliminated, and the voltage and the frequency of the power grid are kept stable.
Preferably, the continuous extended state observer obtaining module comprises:
and the improvement submodule is used for improving the sectional function fal in the traditional extended state observer through an arc tangent function and changing the sectional function fal into a continuous function.
According to the self-synchronizing voltage source control method and system based on the continuous extended state observer, an improved extended state observer algorithm is integrated into the self-synchronizing voltage source control method, so that the whole control process is more flexible and stable, when frequency fluctuation occurs to a load and a new energy power source, the normal state can be recovered more quickly and stably, and the impact of voltage and frequency fluctuation on a power grid and a microgrid is reduced. The problem that the voltage and the frequency of a power grid vibrate and are not stable enough under the disturbance of a new energy power supply due to switching point conversion and gain mutation in the function feedback process of the traditional extended state observer is solved
Drawings
Fig. 1 is a schematic flowchart of a self-synchronous voltage source control method based on a continuous extended state observer according to an embodiment of the present application;
FIG. 2 is a self-synchronizing voltage source device model according to an embodiment of the present application;
FIG. 3 is a flow chart of self-synchronizing voltage source control according to an embodiment of the present application;
FIG. 4 is a self-synchronizing voltage source control block diagram with an extended state observer provided by an embodiment of the present application;
fig. 5 is a schematic structural diagram of a self-synchronizing voltage source control system based on a continuous extended state observer according to an embodiment of the present application.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of implementation in many different ways than those herein set forth and of similar import by those skilled in the art without departing from the spirit of this application and is therefore not limited to the specific implementations disclosed below.
The application provides a self-synchronizing voltage source control method based on a continuous extended state observer, the flow of which is shown in fig. 1, and the method comprises the following steps:
and S101, improving the extended state observer of the self-synchronous voltage source grid-connected device, and changing a piecewise function in the traditional extended state observer into a continuous function to obtain the continuous extended state observer.
Aiming at the problems of switching point judgment and oscillation existing in the extended state observer, the control algorithm is improved, segmented judgment is not needed, and the control algorithm is applied to a self-synchronizing voltage source control algorithm. The self-synchronizing voltage source topology uses a three-phase full-bridge power electronics device as shown in fig. 2.
Wherein u isdcThe power supply is an equivalent new energy power supply; i.e. i1Is a filter inductance LfThe current of (a); i.e. i2Is a filter capacitor CfThe current of (a); i is the output current of the self-synchronizing grid-connected device; e is the output voltage; l isgIs the line impedance.
(1) Self-synchronizing voltage source control
The rapidity of the power electronic converter enables the voltage to change rapidly after being disturbed, and finally the quality of the electric energy is reduced. The synchronous motor has inertia characteristics and damping resistance, and a mechanical equation and an electromotive force balance equation of the synchronous generator are applied to the control of the grid-connected device, so that the port of the power electronic converter shows the inertia characteristics and the damping characteristics of the synchronous generator, voltage sudden change caused by disturbance is responded, and the electric energy quality is improved. The traditional self-synchronizing voltage source control mathematical expression is as follows:
Figure BDA0003033741790000031
the control flow is shown in fig. 3, wherein J is the rotational inertia of the rotor; ω is the synchronous angular rotation speed; omega0Is a given angular velocity of rotation Tm、TeThe torque is respectively the mechanical torque and the electromagnetic torque of the self-synchronizing grid-connected device; psetP is mechanical power and active power, respectively; d is the damping coefficient; emIs a virtual potential command; e0Is a no-load potential; d1Is the voltage regulation factor; q is the reactive power of the output.
(2) Continuous extended state observer design
In consideration of the intermittency and the non-schedulability of the new energy power supply in practical engineering application, the extended state observer is introduced into the control of the self-synchronizing voltage source grid-connected device. The load and the new energy power supply disturbance are estimated through the extended state observer, the load disturbance is used as a compensation item to compensate the virtual torque of the virtual synchronous motor, and the control algorithm of the existing extended state observer is optimized, so that the voltage is further kept stable.
A first order system containing perturbations can be represented as:
Figure BDA0003033741790000041
in the formula: x is a state variable; u (t) and y (t) are the input and output of the system, respectively; d (t) is a perturbation. f (x, d (t), t) is the disturbance in the system. Let x1Let the disturbance term be x2To observe the disturbance term in the system, expanding it to a new state variable, the system can be re-expressed as:
Figure BDA0003033741790000042
in the formula, x2＝f x1,d(t),t+(bb0) u (t), w (t) is the real-time action of the total disturbance of the system.
In order to improve the state tracking efficiency of the state observer, the conventional extended state observer uses a fal function, as shown in equation (4):
Figure BDA0003033741790000043
where e is the tracking error and both α and δ are selected parameters, where α is usually in the range of [0,1 ]. Obviously: fal (e, alpha and delta) is a piecewise function and is a nonlinear function with I, II quadrant mirror symmetry, different expressions need to be switched through switching condition judgment during actual operation, and dynamic gain of the expressions changes suddenly due to the fact that the irreducible characteristic of a switching point. The differential linearization for quadrant I can be obtained:
Figure BDA0003033741790000044
as can be seen from equation (5), the two-terminal gain at the switching point δ is:
Figure BDA0003033741790000045
as can be seen from equation (6), the dynamic gain on the right side of the switching point is α times of that on the left side of the switching point, and the value range of α is [0,1], and the value of α increases abruptly with the decrease of α, so that the piecewise function fal in the conventional extended state observer can be improved by the arctan function, and the piecewise function fal is changed into the continuous function fall, and the expression is:
Figure BDA0003033741790000046
where μ is an error coefficient. Quadrant II works the same.
Thus, the resulting state observer is designed to be:
Figure BDA0003033741790000051
in the formula beta01And beta02Are all the control parameters of the selected extended state observer. The control block diagram of the self-synchronizing grid-connected device with the continuous extended state observer is shown as 4.
And S102, evaluating the load of the power grid system and the disturbance of the new energy power supply through the continuous extended state observer, and compensating the virtual torque of the virtual synchronous motor through the load and the disturbance of the new energy power supply obtained through evaluation, so that the influence of the disturbance on the power grid is eliminated, and the voltage and the frequency of the power grid are kept stable.
In FIG. 4, z2I.e. an estimate of the load disturbance, will be z2The compensation is carried out as a virtual torque compensation item, so that the fluctuation of the new energy power supply can be better coped with, and the stable operation of a high-proportion new energy system is effectively supported.
Based on the same inventive concept, the present application provides a self-synchronizing voltage source control system 500 based on a continuous extended state observer, as shown in fig. 5, comprising:
a continuous extended state observer obtaining module 510, configured to modify an extended state observer of a self-synchronous voltage source grid-connected device, to change a piecewise function in a conventional extended state observer into a continuous function, so as to obtain a continuous extended state observer;
and a voltage and frequency stabilization module 520, configured to evaluate load disturbance of the power grid system through the continuous extended state observer, and compensate the virtual torque of the virtual synchronous motor through the load disturbance obtained through the evaluation, so as to eliminate an influence of new energy power disturbance on the power grid, and keep the voltage and frequency of the power grid stable.
Preferably, the continuous extended state observer obtaining module comprises:
and the improvement submodule is used for improving the sectional function fal in the traditional extended state observer through an arc tangent function and changing the sectional function fal into a continuous function.
The application provides a self-synchronizing voltage source control method and system based on a continuous extended state observer, an improved extended state observer algorithm is integrated into the self-synchronizing voltage source control method, the whole control process is more flexible and stable, when frequency fluctuation occurs in the face of a load and a new energy power source, the normal state can be recovered more quickly and more stably, and impact of voltage and frequency fluctuation on a power grid and a microgrid is reduced. The problem that the voltage and the frequency of a power grid vibrate under the disturbance of a new energy power supply and are not stable enough due to switching point conversion and gain mutation in the function feedback process of the traditional extended state observer is solved.
Finally, it should be noted that: although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention.

Claims (5)

1. A self-synchronizing voltage source control method based on a continuous extended state observer is characterized by comprising the following steps:
the extended state observer of the self-synchronous voltage source grid-connected device is improved, a piecewise function in the traditional extended state observer is changed into a continuous function, and a continuous extended state observer is obtained;
and evaluating the load of the power grid system and the disturbance of the new energy power supply through the continuous extended state observer, and compensating the virtual torque of the virtual synchronous motor through the load and the disturbance of the new energy power supply obtained through evaluation, so that the influence of the disturbance on the power grid is eliminated, and the voltage and the frequency of the power grid are kept stable.
2. The control method according to claim 1, wherein the topology of the self-synchronous voltage source grid-connected device is a three-phase full-bridge power electronic device.
3. The control method of claim 1, wherein converting the piecewise function in a conventional extended state observer to a continuous function comprises:
a piecewise function fal in the traditional extended state observer is improved through an arctangent function, and the piecewise function fal is changed into a continuous function fall.
4. A continuous extended state observer based self-synchronizing voltage source control system, comprising:
the continuous extended state observer obtaining module is used for improving an extended state observer of the self-synchronous voltage source grid-connected device, changing a piecewise function in the traditional extended state observer into a continuous function and obtaining a continuous extended state observer;
and the voltage and frequency stabilization module is used for evaluating the load of the power grid system and the disturbance of the new energy power supply through the continuous extended state observer, and compensating the virtual torque of the virtual synchronous motor through the load and the disturbance of the new energy power supply obtained through evaluation, so that the influence of the disturbance on the power grid is eliminated, and the voltage and the frequency of the power grid are kept stable.
5. The control system of claim 4, wherein the continuous extended state observer acquisition module comprises:
and the improvement submodule is used for improving the sectional function fal in the traditional extended state observer through an arc tangent function and changing the sectional function fal into a continuous function.
CN202110437571.1A 2021-04-22 2021-04-22 Self-synchronizing voltage source control method and system based on continuous extended state observer Pending CN113346515A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114567951A (en) * 2022-03-10 2022-05-31 四维生态科技（杭州）有限公司 Method and device for adjusting lighting system and computer storage medium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114567951A (en) * 2022-03-10 2022-05-31 四维生态科技（杭州）有限公司 Method and device for adjusting lighting system and computer storage medium
CN114567951B (en) * 2022-03-10 2023-12-22 四维生态科技（杭州）有限公司 Method and device for adjusting lighting system and computer storage medium

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