CN112952889A - Optimization method and device of virtual power grid adaptive control strategy and terminal equipment - Google Patents

Optimization method and device of virtual power grid adaptive control strategy and terminal equipment Download PDF

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CN112952889A
CN112952889A CN202110265546.XA CN202110265546A CN112952889A CN 112952889 A CN112952889 A CN 112952889A CN 202110265546 A CN202110265546 A CN 202110265546A CN 112952889 A CN112952889 A CN 112952889A
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power grid
virtual power
control strategy
adaptive control
direct current
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CN112952889B (en
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李桂源
黄伟煌
饶宏
李岩
许树楷
赵晓斌
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China Southern Power Grid Co Ltd
Research Institute of Southern Power Grid Co Ltd
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China Southern Power Grid Co Ltd
Research Institute of 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • H02J3/00125—Transmission line or load transient problems, e.g. overvoltage, resonance or self-excitation of inductive loads
    • 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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H02J2003/365—Reducing harmonics or oscillations in HVDC
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention relates to an optimization method, an optimization device and a terminal device of a virtual power grid self-adaptive control strategy, which are applied to a flexible direct current power transmission system, wherein the optimization method, the optimization device and the terminal device of the virtual power grid self-adaptive control strategy control the virtual power grid self-adaptive control strategy to be switched among a first link, a second link and a third link according to the actual alternating current voltage at the alternating current side of a flexible direct current converter of the flexible direct current power transmission system, so that the risk of resonance of the flexible direct current power transmission system can be reduced, the flexible direct current power transmission system can obtain better dynamic characteristics at the moment of failure and in the process of failure recovery, the flexible direct current power transmission system is prevented from generating overstress to damage a load (a device or equipment), and the safety of direct current fault ride-through of the flexible direct current power; the problem of when adopting current virtual electric wire netting adaptive controller to restrain flexible direct current transmission line's high frequency resonance, can have the dynamic characteristic relatively poor in the alternating current fault recovery process is solved.

Description

Optimization method and device of virtual power grid adaptive control strategy and terminal equipment
Technical Field
The invention relates to the technical field of electric power, in particular to a method and a device for optimizing a virtual power grid adaptive control strategy and terminal equipment.
Background
The flexible direct current transmission is a trend of development of a future power system, and several key technical problems which need to be solved by applying the flexible direct current transmission are solved, wherein one of the key technical problems is to inhibit high-frequency resonance between the flexible direct current and an alternating current system, and the high-frequency resonance is mainly caused by the fact that a flexible direct current converter of the flexible direct current transmission presents negative impedance to amplify harmonic waves of a power transmission system and is also caused by impedance mismatching of the flexible direct current converter and the alternating current system. The high frequency resonance is mainly related to the control link delay and feedforward strategy of the flexible direct current transmission. For the high-frequency resonance, the main solution in the flexible direct-current transmission project at present is to reasonably configure a filter strategy in a feedforward link of an inner ring controller of a flexible direct-current station, namely a strategy of a self-adaptive controller of a virtual power grid.
When the virtual power grid adaptive controller strategy adopts low-pass filtering and nonlinear filtering to suppress the high-frequency resonance of the flexible direct-current power transmission, the technical problem of deteriorating the dynamic characteristic of the power system exists. For example, the input quantity and the output quantity of the virtual power grid adaptive controller under the normal working condition disclosed by the flexible direct current high-frequency resonance method, the flexible direct current high-frequency resonance system and the flexible direct current high-frequency resonance equipment with the notice number of CN111799833A in 10/20/2020 by the intellectual property office are completely isolated physically, and the harmonic wave of the actual electric quantity cannot be reflected on the virtual electric quantity, so that the effect of inhibiting the harmonic wave is achieved. When the effective value of the actually input actual alternating voltage is reduced from the normal value to meet the preset condition, the virtual electric quantity is completely equal to the actual electric quantity, so that the actual electric quantity is completely tracked in real time, and the dynamic characteristic of the power system at the moment of failure is improved; after the tracking is completed for a period of time, if the effective value of the actual alternating voltage is smaller than the preset threshold value, the adaptive tracking is started until the actual electric quantity is recovered to a stable value, and the technical problem is solved. Because the filtering process of the virtual power grid adaptive controller strategy is divided into three links, namely, no response to the tiny change of the actual electric quantity under the normal working condition, complete tracking of the actual electric quantity at the moment of a fault, and self-adaptive tracking of the actual electric quantity during the fault and recovery, when the flexible direct-current power transmission adopts the current virtual power grid adaptive control strategy, smooth switching among the three links is needed, and the problem of poor dynamic characteristics can exist in the alternating-current fault recovery process.
Therefore, in a flexible direct current transmission system, how to ensure that a virtual grid filter in a virtual grid adaptive controller strategy is smoothly switched among three links so as to obtain a good resonance suppression effect and good dynamic characteristics of the transmission system (starting of the transmission system, instant of an alternating current fault and a fault recovery process) becomes a problem to be solved in the field.
Disclosure of Invention
The embodiment of the invention provides an optimization method, an optimization device and terminal equipment of a virtual power grid adaptive control strategy, which are used for solving the technical problem of poor dynamic characteristics in an alternating current fault recovery process when the high-frequency resonance of a flexible direct current transmission line is inhibited by adopting the conventional virtual power grid adaptive controller.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
a method for optimizing a virtual power grid adaptive control strategy is applied to a flexible direct current power transmission system and is suitable for installing a virtual power grid adaptive controller in a feedforward link of a current inner loop controller in the flexible direct current power transmission system in advance, and the method for optimizing the virtual power grid adaptive control strategy comprises the following steps:
s10, when the flexible direct current power transmission system starts a virtual power grid adaptive control strategy, controlling the output of a virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller and keeping the output unchanged, namely, the virtual power grid adaptive control strategy enters a first link to obtain a first actual alternating current voltage at the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
s20, if the effective value of the first actual alternating voltage is larger than a first preset value, the output of the virtual power grid self-adaptive controller is kept unchanged, namely the virtual power grid self-adaptive control strategy is always in the first link;
s30, if the effective value of the first actual alternating voltage is not larger than a first preset value, controlling the output of the virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller, and enabling the virtual power grid adaptive control strategy to enter a second link to obtain the tracking time when the output of the virtual power grid adaptive controller is completely equal to the input of the virtual power grid adaptive controller;
s40, if the tracking time reaches a time set value, controlling a virtual power grid adaptive control strategy to enter a third link, and simultaneously obtaining a second actual alternating voltage on the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
s50, if the effective value of the second actual alternating voltage is larger than the first preset value, controlling the virtual power grid adaptive control strategy to exit a third link, and simultaneously obtaining a voltage difference value between the output of the virtual power grid adaptive controller and the input of the virtual power grid adaptive controller;
s60, if the voltage difference value is larger than a second preset value, controlling the output of the virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller, and switching the virtual power grid adaptive control strategy from the third link to the first link;
s70, if the voltage difference value is not larger than a second preset value, controlling a virtual power grid adaptive control strategy to be directly switched from the third link to the first link;
the first step is that the self-adaptive control strategy of the virtual power grid is in a state of not responding to tiny change of actual electric quantity under normal working conditions; the second step is that the self-adaptive control strategy of the virtual power grid is in a state of completely tracking actual electric quantity at fault instant; and the third step is that the self-adaptive control strategy of the virtual power grid is in a state of self-adaptively tracking actual electric quantity during fault and recovery.
Preferably, in step S20, the first preset value ranges from 0.7pu to 0.9 pu.
Preferably, in step S40, the time set value ranges from 2ms to 15 ms.
Preferably, in step S60, the second preset value ranges from 0.005pu to 0.02 pu.
Preferably, before step S10, the method for optimizing the virtual power grid adaptive control strategy further includes: the converter unlocking signal is not received in the flexible direct-current power transmission system, and a virtual power grid self-adaptive control strategy is not required to be started; and receiving a converter unlocking signal at the flexible direct current transmission system, and starting a virtual power grid self-adaptive control strategy.
The invention also provides an optimization device of the virtual power grid adaptive control strategy, which is applied to the flexible direct current power transmission system and is suitable for installing the virtual power grid adaptive controller in a feedforward link of a current inner loop controller in the flexible direct current power transmission system in advance, wherein the optimization device comprises a voltage acquisition module, a first execution module, a second execution module, a third execution module, a fourth execution module, a fifth execution module and a sixth execution module;
the voltage obtaining module is used for starting a virtual power grid self-adaptive control strategy according to the flexible direct current power transmission system, controlling the output of the virtual power grid self-adaptive controller to be equal to the input of the virtual power grid self-adaptive controller and keeping the output unchanged, namely, the virtual power grid self-adaptive control strategy enters a first link to obtain a first actual alternating current voltage at the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
the first execution module is configured to, according to that the effective value of the first actual ac voltage is greater than a first preset value, keep an output of the virtual power grid adaptive controller unchanged, that is, the virtual power grid adaptive control strategy is always in the first link;
the second execution module is used for controlling the output of the virtual power grid self-adaptive controller to be equal to the input of the virtual power grid self-adaptive controller according to the condition that the effective value of the first actual alternating voltage is not larger than a first preset value, and the virtual power grid self-adaptive control strategy enters a second link to obtain the tracking time that the output of the virtual power grid self-adaptive controller is completely equal to the input of the virtual power grid self-adaptive controller;
the third execution module is used for controlling the virtual power grid adaptive control strategy to enter a third link according to the tracking time reaching a time set value, and simultaneously acquiring a second actual alternating voltage at the alternating current side of the flexible direct current converter in the flexible direct current power transmission system;
the fourth execution module is used for controlling the virtual power grid adaptive control strategy to exit the third link and simultaneously acquiring a voltage difference value between the output of the virtual power grid adaptive controller and the input of the virtual power grid adaptive controller according to the fact that the effective value of the second actual alternating voltage is larger than the first preset value;
the fifth execution module is configured to control an output of the virtual power grid adaptive controller to be equal to an input of the virtual power grid adaptive controller according to the voltage difference value being greater than the second preset value, and the virtual power grid adaptive control strategy is switched from the third link to the first link;
the sixth execution module is configured to control the virtual power grid adaptive control strategy to be directly switched from the third link to the first link according to the voltage difference value being not greater than the second preset value;
the first step is that the self-adaptive control strategy of the virtual power grid is in a state of not responding to tiny change of actual electric quantity under normal working conditions; the second step is that the self-adaptive control strategy of the virtual power grid is in a state of completely tracking actual electric quantity at fault instant; and the third step is that the self-adaptive control strategy of the virtual power grid is in a state of self-adaptively tracking actual electric quantity during fault and recovery.
Preferably, the first preset value ranges from 0.7pu to 0.9 pu.
Preferably, the time set value ranges from 2ms to 15 ms.
Preferably, the second preset value ranges from 0.005pu to 0.02 pu.
Preferably, the apparatus for optimizing the virtual power grid adaptive control strategy further includes: the system comprises a starting determining module, a judging module and a judging module, wherein the starting determining module is used for not receiving a converter unlocking signal according to the condition that the flexible direct current transmission system does not need to start a virtual power grid self-adaptive control strategy; or starting the self-adaptive control strategy of the virtual power grid according to the unlocking signal of the converter received by the flexible direct current transmission system
The present invention also provides a computer-readable storage medium for storing computer instructions, which, when run on a computer, cause the computer to execute the above-mentioned optimization method for the virtual grid adaptive control strategy.
The invention also provides terminal equipment, which comprises 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 optimization method of the virtual power grid adaptive control strategy according to the instruction in the program code.
According to the technical scheme, the embodiment of the invention has the following advantages: according to the optimization method, the device and the terminal equipment of the virtual power grid self-adaptive control strategy, the virtual power grid self-adaptive control strategy is controlled to be switched among the first link, the second link and the third link according to the actual alternating voltage on the alternating current side of the flexible direct current converter of the flexible direct current transmission system, so that the risk of resonance of the flexible direct current transmission system can be reduced, the flexible direct current transmission system can obtain better dynamic characteristics at the moment of failure and in the failure recovery process, the flexible direct current transmission system is prevented from generating overstress to damage a load (a device or equipment), and the safety of direct current fault ride-through of the flexible direct current transmission system is improved; the technical problem that dynamic characteristics are poor in the AC fault recovery process when the high-frequency resonance of the flexible DC transmission line is restrained by adopting the existing virtual power grid self-adaptive controller is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a flowchart illustrating steps of a method for optimizing a virtual power grid adaptive control strategy according to an embodiment of the present invention.
Fig. 2 is a tracking schematic diagram of a virtual power grid adaptive controller in the optimization method of the virtual power grid adaptive control strategy according to the embodiment of the present invention.
Fig. 3 is a schematic structural diagram of positive sequence inner loop control of the flexible direct current power transmission system of the virtual power grid adaptive control strategy in the optimization method of the virtual power grid adaptive control strategy according to the embodiment of the present invention.
Fig. 4 is a schematic structural diagram of negative sequence inner loop control of a flexible direct current transmission system of a virtual power grid adaptive control strategy in the optimization method of the virtual power grid adaptive control strategy according to the embodiment of the present invention.
Fig. 5 is a block diagram of an optimization apparatus for a virtual power grid adaptive control strategy according to an embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The current widely adopted engineering is vector control based on direct current control, and an outer loop control strategyAnd the inner ring control strategy is mainly based on a flexible direct current mathematical model under a dq rotating coordinate system, and the decoupling control is respectively carried out on the d-axis component and the q-axis component of the voltage fundamental wave at the valve side of the valve group, so that the power exchange between an alternating current system and a direct current system is realized, the current can be effectively limited, and the good response characteristic is also realized. The structure of the inner ring controller is shown in fig. 3 and 4, the flexible direct current inner ring control link receives the reference value I of active and reactive current from the outer ring controldrefAnd IqrefThrough a proportional-integral link, reference current is quickly tracked, the control on the dq component of the alternating-current side voltage of the valve bank is realized, and the amplitude and the phase of the alternating-current side voltage of the valve bank can be changed by changing the Vd and Vq components, so that the power exchange between alternating-current and direct-current systems is realized. The current inner loop control adopts double dq decoupling control (positive sequence and negative sequence); the positive sequence inner ring controller tracks an active reactive current reference value, and the negative sequence inner ring has the main function of controlling a negative sequence current component generated under the asymmetrical working condition of a power grid to be zero as asymmetrical fault control so as to prevent valve group overcurrent and power module capacitor overvoltage. The virtual power grid self-adaptive controller is mainly used for a positive sequence inner loop voltage feedforward link and a negative sequence inner loop voltage feedforward link. The angle of the positive sequence coordinate transformation is the angle of the phase-locked loop; the angle of the negative sequence coordinate transformation is the angle of the phase locked loop after multiplying the angle by-1.
The embodiment of the application provides an optimization method and device of a virtual power grid adaptive control strategy and terminal equipment, and aims to solve the technical problem that dynamic characteristics are poor in an alternating current fault recovery process when an existing virtual power grid adaptive controller is adopted to suppress high-frequency resonance of a flexible direct current transmission line.
The first embodiment is as follows:
fig. 1 is a flowchart illustrating steps of a method for optimizing a virtual power grid adaptive control strategy according to an embodiment of the present invention, and fig. 2 is a schematic tracking diagram illustrating a virtual power grid adaptive controller in the method for optimizing a virtual power grid adaptive control strategy according to an embodiment of the present invention.
As shown in fig. 1 and fig. 2, an embodiment of the present invention provides an optimization method for a virtual power grid adaptive control strategy, which is applied to a flexible direct current power transmission system and is suitable for installing a virtual power grid adaptive controller in a feed-forward link of a current inner loop controller in the flexible direct current power transmission system in advance, where the optimization method includes the following steps:
s10, when the flexible direct current power transmission system starts a virtual power grid adaptive control strategy, controlling the output of a virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller and keeping the input unchanged, namely, the virtual power grid adaptive control strategy enters a first link to obtain a first actual alternating current voltage at the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
s20, if the effective value of the first actual alternating voltage is larger than a first preset value, the output of the virtual power grid self-adaptive controller is kept unchanged, namely the virtual power grid self-adaptive control strategy is always in a first link;
s30, if the effective value of the first actual alternating voltage is not larger than a first preset value, controlling the output of the virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller, and enabling the virtual power grid adaptive control strategy to enter a second link to obtain the tracking time when the output of the virtual power grid adaptive controller is completely equal to the input of the virtual power grid adaptive controller;
s40, if the tracking time reaches a time set value, controlling a virtual power grid adaptive control strategy to enter a third link, and simultaneously obtaining a second actual alternating voltage on the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
s50, if the effective value of the second actual alternating voltage is larger than the first preset value, controlling the virtual power grid adaptive control strategy to exit a third link, and simultaneously obtaining a voltage difference value between the output of the virtual power grid adaptive controller and the input of the virtual power grid adaptive controller;
s60, if the voltage difference value is larger than a second preset value, controlling the output of the virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller, and switching the virtual power grid adaptive control strategy from a third link to a first link;
s70, if the voltage difference value is not larger than a second preset value, controlling the self-adaptive control strategy of the virtual power grid to be directly switched from the third link to the first link;
the method comprises the following steps that a first step is that a virtual power grid self-adaptive control strategy is in a state of not responding to small changes of actual electric quantity under normal working conditions; the second step is that the self-adaptive control strategy of the virtual power grid is in a state of completely tracking actual electric quantity at fault instant; and the third step is that the self-adaptive control strategy of the virtual power grid is in a state of self-adaptively tracking actual electric quantity during fault and recovery.
In this embodiment of the present invention, before step S10, the method for optimizing a virtual power grid adaptive control strategy further includes: the converter unlocking signal is not received in the flexible direct-current power transmission system, and a virtual power grid self-adaptive control strategy is not required to be started; and receiving a converter unlocking signal at the flexible direct current transmission system, and starting a virtual power grid self-adaptive control strategy.
It should be noted that before the converter of the flexible direct current transmission system is unlocked, there is no resonance problem, the flexible direct current transmission system does not need to start the virtual power grid adaptive control strategy, and only after the converter of the flexible direct current transmission system is unlocked, the virtual power grid adaptive control strategy needs to be started to suppress the high-frequency resonance of the flexible direct current transmission line.
In step S10 of the embodiment of the present invention, after the flexible dc power transmission system starts the virtual power grid adaptive control strategy, the output of the virtual power grid adaptive controller of the flexible dc power transmission system is controlled to be equal to the input of the virtual power grid adaptive controller at the moment of unlocking the inverter, and the output of the virtual power grid adaptive controller (virtual power grid adaptive controller) is kept unchanged, and the virtual power grid adaptive control strategy formally enters a first link of "normal operating condition does not respond to a small change in actual electric quantity", and further obtains a first actual ac voltage on the ac side of the flexible dc power converter in the flexible dc power transmission system.
It should be noted that the content of obtaining the first actual ac voltage on the ac side of the vdc converter in the vdc transmission system is described in detail in the patent document with publication number CN111799833A, which discloses a method, a system and an apparatus for high frequency resonance of vdc, and is not described in this embodiment.
In steps S20 and S30 of the embodiment of the present invention, the determination of the effective value of the first actual ac voltage to obtain the tracking time is described in detail in the patent document with publication No. CN111799833A, which discloses a flexible dc high-frequency resonance method, system and apparatus, and will not be described in detail in this embodiment.
It should be noted that the first preset value ranges from 0.7pu to 0.9 pu.
In step S40 of the embodiment of the present invention, the virtual power grid adaptive control strategy is controlled to switch from the second link to the third link according to whether the tracking time reaches the set time setting value, and a second actual ac voltage of the flexible dc power transmission system at this time is obtained.
The time set value is in the range of 2ms to 15 ms.
In step S50 of the embodiment of the present invention, it is mainly determined whether the effective value of the second actual ac voltage is greater than a threshold value, and the virtual power grid adaptive control policy is controlled to exit the third link.
In step S60 and step S70 of the embodiment of the present invention, whether the virtual power grid adaptive control strategy is directly switched from the third link to the first link is mainly controlled according to whether the voltage difference satisfies the second preset value.
It should be noted that the second preset value ranges from 0.005pu to 0.02 pu.
According to the optimization method of the virtual power grid self-adaptive control strategy, the virtual power grid self-adaptive control strategy is controlled to be switched among the first link, the second link and the third link according to the actual alternating voltage on the alternating current side of the flexible direct current converter of the flexible direct current power transmission system, so that the risk of resonance of the flexible direct current power transmission system can be reduced, the flexible direct current power transmission system can obtain better dynamic characteristics at the moment of failure and in the failure recovery process, the flexible direct current power transmission system is prevented from generating overstress to damage a load (a device or equipment), and the safety of direct current fault ride-through of the flexible direct current power transmission system is improved; the technical problem that dynamic characteristics are poor in the AC fault recovery process when the high-frequency resonance of the flexible DC transmission line is restrained by adopting the existing virtual power grid self-adaptive controller is solved.
In the embodiment of the invention, the optimization method of the virtual power grid adaptive control strategy is mainly used for controlling link switching between a first link and a third link in the AC fault recovery process of the virtual power grid adaptive control strategy after the virtual power grid adaptive control strategy is started for the flexible DC power transmission system, so that the situation that the dynamic characteristic of the virtual power grid adaptive control strategy is poor in the link switching process, and the load connected with the flexible DC power transmission system is damaged is avoided.
Example two:
fig. 5 is a block diagram of an optimization apparatus for a virtual power grid adaptive control strategy according to an embodiment of the present invention.
As shown in fig. 5, an embodiment of the present invention further provides an optimization apparatus for a virtual power grid adaptive control strategy, which is applied to a flexible direct current power transmission system and is suitable for installing a virtual power grid adaptive controller in a feed-forward link of a current inner loop controller in the flexible direct current power transmission system in advance, where the optimization apparatus includes a voltage obtaining module 10, a first execution module 20, a second execution module 30, a third execution module 40, a fourth execution module 50, a fifth execution module 60, and a sixth execution module 70;
the voltage obtaining module 10 is configured to start a virtual power grid adaptive control strategy according to the flexible direct current power transmission system, and control an output of the virtual power grid adaptive controller to be equal to an input of the virtual power grid adaptive controller and to remain unchanged, that is, the virtual power grid adaptive control strategy enters a first link to obtain a first actual alternating current voltage on an alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
the first execution module 20 is configured to, according to that the effective value of the first actual ac voltage is greater than a first preset value, keep an output of the virtual power grid adaptive controller unchanged, that is, a virtual power grid adaptive control strategy is always in a first link;
the second execution module 30 is configured to control the output of the virtual grid adaptive controller to be equal to the input of the virtual grid adaptive controller according to that the effective value of the first actual alternating voltage is not greater than the first preset value, and the virtual grid adaptive control strategy enters a second link to obtain a tracking time when the output of the virtual grid adaptive controller is completely equal to the input of the virtual grid adaptive controller;
the third execution module 40 is configured to control the virtual power grid adaptive control strategy to enter a third link according to the tracking time reaching the time set value, and obtain a second actual alternating-current voltage at the alternating-current side of the flexible direct-current converter in the flexible direct-current power transmission system;
the fourth execution module 50 is configured to control the virtual power grid adaptive control strategy to exit the third link according to that the effective value of the second actual alternating voltage is greater than the first preset value, and simultaneously obtain a voltage difference value between an output of the virtual power grid adaptive controller and an input of the virtual power grid adaptive controller;
a fifth executing module 60, configured to control an output of the virtual power grid adaptive controller to be equal to an input of the virtual power grid adaptive controller according to the voltage difference being greater than the second preset value, and switch the virtual power grid adaptive control policy from the third link to the first link;
a sixth executing module 70, configured to control the virtual power grid adaptive control strategy to directly switch from the third link to the first link according to the voltage difference value not greater than the second preset value;
the method comprises the following steps that a first step is that a virtual power grid self-adaptive control strategy is in a state of not responding to small changes of actual electric quantity under normal working conditions; the second step is that the self-adaptive control strategy of the virtual power grid is in a state of completely tracking actual electric quantity at fault instant; and the third step is that the self-adaptive control strategy of the virtual power grid is in a state of self-adaptively tracking actual electric quantity during fault and recovery.
In the embodiment of the invention, the range of the first preset value is 0.7 pu-0.9 pu; the range of the time set value is 2 ms-15 ms; the second preset value ranges from 0.005pu to 0.02 pu.
In this embodiment of the present invention, the apparatus for optimizing a virtual power grid adaptive control strategy further includes: the system comprises a starting determining module, a judging module and a judging module, wherein the starting determining module is used for not receiving a converter unlocking signal according to the condition that the flexible direct current transmission system does not receive the converter unlocking signal and does not need to start a virtual power grid self-adaptive control strategy; or starting the self-adaptive control strategy of the virtual power grid according to the converter unlocking signal received by the flexible direct current transmission system.
It should be noted that the modules in the second embodiment correspond to the steps in the first embodiment, and the steps in the first embodiment have been described in detail in the first embodiment, and the contents of the modules in the second embodiment are not described in detail in this second embodiment.
Example three:
the embodiment of the invention provides a computer-readable storage medium, which is used for storing computer instructions, and when the computer instructions run on a computer, the computer is enabled to execute the optimization method of the virtual power grid adaptive control strategy.
Example four:
the embodiment of the invention provides terminal equipment, which comprises a processor and a memory;
a memory for storing the program code and transmitting the program code to the processor;
and the processor is used for executing the optimization method of the virtual power grid adaptive control strategy according to the instructions in the program codes.
It should be noted that the processor is configured to execute the steps in the above-described embodiment of the optimization method of the virtual grid adaptive control strategy according to the instructions in the program code. Alternatively, the processor, when executing the computer program, implements the functions of each module/unit in each system/apparatus embodiment described above.
Illustratively, a computer program may be partitioned into one or more modules/units, which are stored in a memory and executed by a processor to accomplish the present application. One or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of a computer program in a terminal device.
The terminal device may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal device may include, but is not limited to, a processor, a memory. Those skilled in the art will appreciate that the terminal device is not limited and may include more or fewer components than those shown, or some components may be combined, or different components, e.g., the terminal device may also include input output devices, network access devices, buses, etc.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage may be an internal storage unit of the terminal device, such as a hard disk or a memory of the terminal device. The memory may also be an external storage device of the terminal device, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the terminal device. Further, the memory may also include both an internal storage unit of the terminal device and an external storage device. The memory is used for storing computer programs and other programs and data required by the terminal device. The memory may also be used to temporarily store data that has been output or is to be output.
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 system, apparatus and method may be implemented in other manners. 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 invention 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 invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. 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-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will 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 of the embodiments of the present invention.

Claims (10)

1. A method for optimizing a virtual power grid adaptive control strategy is applied to a flexible direct current power transmission system and is suitable for installing a virtual power grid adaptive controller in a feedforward link of a current inner loop controller in the flexible direct current power transmission system in advance, and the method for optimizing the virtual power grid adaptive control strategy comprises the following steps:
s10, when the flexible direct current power transmission system starts a virtual power grid adaptive control strategy, controlling the output of a virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller and keeping the output unchanged, namely, the virtual power grid adaptive control strategy enters a first link to obtain a first actual alternating current voltage at the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
s20, if the effective value of the first actual alternating voltage is larger than a first preset value, the output of the virtual power grid self-adaptive controller is kept unchanged, namely the virtual power grid self-adaptive control strategy is always in the first link;
s30, if the effective value of the first actual alternating voltage is not larger than a first preset value, controlling the output of the virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller, and enabling the virtual power grid adaptive control strategy to enter a second link to obtain the tracking time when the output of the virtual power grid adaptive controller is completely equal to the input of the virtual power grid adaptive controller; it is characterized in that the preparation method is characterized in that,
s40, if the tracking time reaches a time set value, controlling a virtual power grid adaptive control strategy to enter a third link, and simultaneously obtaining a second actual alternating voltage on the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
s50, if the effective value of the second actual alternating voltage is larger than the first preset value, controlling the virtual power grid adaptive control strategy to exit a third link, and simultaneously obtaining a voltage difference value between the output of the virtual power grid adaptive controller and the input of the virtual power grid adaptive controller;
s60, if the voltage difference value is larger than a second preset value, controlling the output of the virtual power grid adaptive controller to be equal to the input of the virtual power grid adaptive controller, and switching the virtual power grid adaptive control strategy from the third link to the first link;
s70, if the voltage difference value is not larger than a second preset value, controlling a virtual power grid adaptive control strategy to be directly switched from the third link to the first link;
the first step is that the self-adaptive control strategy of the virtual power grid is in a state of not responding to tiny change of actual electric quantity under normal working conditions; the second step is that the self-adaptive control strategy of the virtual power grid is in a state of completely tracking actual electric quantity at fault instant; and the third step is that the self-adaptive control strategy of the virtual power grid is in a state of self-adaptively tracking actual electric quantity during fault and recovery.
2. The optimization method of the adaptive control strategy for the virtual power grid according to claim 1, wherein in step S20, the first preset value ranges from 0.7pu to 0.9 pu.
3. The method for optimizing the adaptive control strategy for the virtual power grid according to claim 1, wherein in step S40, the time setting value ranges from 2ms to 15 ms.
4. The optimization method of the adaptive control strategy for the virtual power grid according to claim 1, wherein in step S60, the second preset value ranges from 0.005pu to 0.02 pu.
5. The method for optimizing the adaptive control strategy for the virtual power grid according to claim 1, wherein before step S10, the method further comprises: the converter unlocking signal is not received in the flexible direct-current power transmission system, and a virtual power grid self-adaptive control strategy is not required to be started; and receiving a converter unlocking signal at the flexible direct current transmission system, and starting a virtual power grid self-adaptive control strategy.
6. An optimization device of a virtual power grid adaptive control strategy is applied to a flexible direct current power transmission system and is suitable for mounting a virtual power grid adaptive controller in a feedforward link of a current inner loop controller in the flexible direct current power transmission system in advance, and is characterized by comprising a voltage acquisition module, a first execution module, a second execution module, a third execution module, a fourth execution module, a fifth execution module and a sixth execution module;
the voltage obtaining module is used for starting a virtual power grid self-adaptive control strategy according to the flexible direct current power transmission system, controlling the output of the virtual power grid self-adaptive controller to be equal to the input of the virtual power grid self-adaptive controller and keeping the output unchanged, namely, the virtual power grid self-adaptive control strategy enters a first link to obtain a first actual alternating current voltage at the alternating current side of a flexible direct current converter in the flexible direct current power transmission system;
the first execution module is configured to, according to that the effective value of the first actual ac voltage is greater than a first preset value, keep an output of the virtual power grid adaptive controller unchanged, that is, the virtual power grid adaptive control strategy is always in the first link;
the second execution module is used for controlling the output of the virtual power grid self-adaptive controller to be equal to the input of the virtual power grid self-adaptive controller according to the condition that the effective value of the first actual alternating voltage is not larger than a first preset value, and the virtual power grid self-adaptive control strategy enters a second link to obtain the tracking time that the output of the virtual power grid self-adaptive controller is completely equal to the input of the virtual power grid self-adaptive controller;
the third execution module is used for controlling the virtual power grid adaptive control strategy to enter a third link according to the tracking time reaching a time set value, and simultaneously acquiring a second actual alternating voltage at the alternating current side of the flexible direct current converter in the flexible direct current power transmission system;
the fourth execution module is used for controlling the virtual power grid adaptive control strategy to exit the third link and simultaneously acquiring a voltage difference value between the output of the virtual power grid adaptive controller and the input of the virtual power grid adaptive controller according to the fact that the effective value of the second actual alternating voltage is larger than the first preset value;
the fifth execution module is configured to control an output of the virtual power grid adaptive controller to be equal to an input of the virtual power grid adaptive controller according to the voltage difference value being greater than the second preset value, and the virtual power grid adaptive control strategy is switched from the third link to the first link;
the sixth execution module is configured to control the virtual power grid adaptive control strategy to be directly switched from the third link to the first link according to the voltage difference value being not greater than the second preset value;
the first step is that the self-adaptive control strategy of the virtual power grid is in a state of not responding to tiny change of actual electric quantity under normal working conditions; the second step is that the self-adaptive control strategy of the virtual power grid is in a state of completely tracking actual electric quantity at fault instant; and the third step is that the self-adaptive control strategy of the virtual power grid is in a state of self-adaptively tracking actual electric quantity during fault and recovery.
7. The apparatus according to claim 6, wherein the first preset value ranges from 0.7pu to 0.9pu, the second preset value ranges from 0.005pu to 0.02pu, and the time setting value ranges from 2ms to 15 ms.
8. The apparatus for optimizing the adaptive control strategy for a virtual power grid according to claim 6, further comprising: the system comprises a starting determining module, a judging module and a judging module, wherein the starting determining module is used for not receiving a converter unlocking signal according to the condition that the flexible direct current transmission system does not need to start a virtual power grid self-adaptive control strategy; or starting the self-adaptive control strategy of the virtual power grid according to the converter unlocking signal received by the flexible direct current transmission system.
9. A computer-readable storage medium for storing computer instructions which, when executed on a computer, cause the computer to perform the method of optimizing virtual power grid adaptive control strategy according to any one of claims 1-5.
10. A terminal device 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 optimization method of the virtual power grid adaptive control strategy according to any one of claims 1 to 5 according to instructions in the program code.
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