CN111541263B - Harmonic control strategy evaluation method, system and equipment for flexible direct current transmission system - Google Patents
Harmonic control strategy evaluation method, system and equipment for flexible direct current transmission system Download PDFInfo
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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
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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
- H02J3/01—Arrangements for reducing harmonics or ripples
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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
- H02J2003/365—Reducing harmonics or oscillations in HVDC
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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
- 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]
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- 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
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- 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]
Abstract
The embodiment of the invention relates to a harmonic control strategy evaluation method, a harmonic control strategy evaluation system and harmonic control equipment for a flexible direct current power transmission system, which are used for evaluating the harmonic control strategy of the flexible direct current power transmission system and comprise the steps of obtaining flexible direct current alternating current impedance and alternating current power grid impedance to obtain flexible direct current alternating current impedance amplitude A and flexible direct current alternating current impedance phase phiAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the phase difference phi between the impedance of the alternating current power grid and the flexible direct current alternating current impedance; KB if any one of the operating conditions>A, and phi>180 DEG + beta or phi<180 + beta, the operating condition contains resonance. By the harmonic control strategy evaluation method for the flexible direct current transmission system, hundreds of resonance risks of thousands of operation conditions can be evaluated within a minute-scale time, workload is greatly simplified, and whether the harmonic control strategy meets the requirements of the flexible direct current transmission system or not is gradually known, so that stable operation of the flexible direct current transmission system is improved.
Description
Technical Field
The invention relates to the technical field of flexible direct current transmission, in particular to a harmonic control strategy evaluation method, system and equipment for a flexible direct current transmission system.
Background
The flexible direct current transmission is a novel transmission technology based on a voltage source converter, a self-turn-off device and a Pulse Width Modulation (PWM) technology, compared with the traditional direct current transmission technology, the flexible direct current transmission technology has the advantages of being capable of supplying power to a passive network, avoiding phase change failure, being easy to form a multi-terminal direct current system and the like, is also used for supplying power in a wind power plant grid, asynchronous networking and city, improving traditional direct current operation characteristics and the like, shows huge economic and technical advantages in application occasions, is an important technical basis for building a direct current power grid and developing an energy internet in the future, and is one of important development directions in the field of power transmission in the future.
The flexible direct-current transmission is a new generation direct-current transmission technology based on a voltage source type converter, has remarkable advantages in the aspects of new energy consumption, economy, flexibility, reliability and the like, and is rapidly developed in recent years. However, with the increasing of the flexible direct current transmission capacity and the large-scale application of high-power electronic equipment in the power grid, the existing flexible direct current transmission and the access to the power grid generate high-frequency resonance, and the high-frequency resonance affects the safe operation stability of the power grid and the safety of the power equipment in the power grid.
Disclosure of Invention
The embodiment of the invention provides a harmonic control strategy evaluation method, system and equipment for a flexible direct current transmission system, which are used for solving the technical problems that the existing flexible direct current transmission and access to a power grid can generate high-frequency resonance, and the high-frequency resonance influences the safe operation stability of the power grid and the safety of power equipment in the power grid.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
a harmonic control strategy evaluation method of a flexible direct current transmission system is used for evaluating a harmonic control strategy of the flexible direct current transmission system and comprises the following steps:
s1, acquiring flexible direct current alternating current impedance in a flexible direct current power transmission system and alternating current power grid impedance of each operation mode of the flexible direct current power transmission system accessing an electric network point;
s2, obtaining a flexible direct current alternating current impedance amplitude A and a flexible direct current alternating current impedance phase phi according to the flexible direct current alternating current impedance and the alternating current power grid impedanceAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the phase difference phi between the flexible direct current alternating current impedance and the alternating current power grid impedance by subtracting the flexible direct current alternating current impedance phase from the alternating current power grid impedance phase of each operation mode;
s3, if KB is greater than A and phi is greater than 180 degrees + beta or phi < -180 degrees + beta in any one operation working condition, the operation working condition in the harmonic control strategy of the flexible direct-current power transmission system contains resonance;
the working condition under the operation mode in the harmonic control strategy of the flexible direct current transmission system is an operation working condition formed by combining an operation mode of a power grid and a connection mode of the power grid, beta is a phase angle margin, and K is an amplitude margin coefficient.
Preferably, the harmonic control strategy evaluation method for the flexible direct-current transmission system further comprises the step of judging whether the working condition of resonance generation is acceptable;
if the working condition of the resonance is not acceptable, the harmonic control strategy of the flexible direct current transmission system needs to be optimized, and the optimized harmonic control strategy of the flexible direct current transmission system executes the steps S1 to S3 again until the working condition of the resonance is acceptable or no resonance exists in the flexible direct current transmission system;
and if the resonance working condition can be accepted, outputting the control parameters of the harmonic control strategy of the flexible direct current transmission system.
Preferably, in step S1, the flexible dc/ac impedance is obtained by scanning the flexible dc power transmission system using an off-line simulation or a real-time simulation.
Preferably, the flexible direct current and alternating current impedance is a flexible direct current and alternating current impedance of a converter station in a flexible direct current transmission system.
Preferably, according to the operation mode of the grid, the ac grid impedance of each operation mode at the grid point of the flexible dc transmission system access is analyzed by using NimScan in step S1.
Preferably, the flexible dc-ac impedance has the same frequency resolution as the ac grid impedance.
Preferably, the amplitude margin coefficient is
Wherein C is the amplitude margin.
Preferably, the amplitude margin is 3 and the phase angle margin is 5.
The invention also provides a harmonic control strategy evaluation system of the flexible direct current power transmission system, which comprises a data acquisition unit, a data processing unit, an evaluation unit and a judgment unit;
the data acquisition unit is used for acquiring the flexible direct current alternating current impedance in the flexible direct current transmission system and the alternating current power grid impedance of each operation mode of the flexible direct current transmission system accessing the power grid point;
the data processing unit is used for obtaining a flexible direct current alternating current impedance amplitude A and a flexible direct current alternating current impedance phase phi according to the flexible direct current alternating current impedance and the alternating current power grid impedanceAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the phase difference phi between the flexible direct current alternating current impedance and the alternating current power grid impedance by subtracting the flexible direct current alternating current impedance phase from the alternating current power grid impedance phase of each operation mode;
the evaluation unit is used for determining whether the operating condition in the harmonic control strategy of the flexible direct current transmission system contains resonance according to KB > A and phi >180 DEG + beta or phi < -180 DEG + beta in any operating condition;
the judging unit is used for judging that the harmonic control strategy of the flexible direct-current transmission system needs to be optimized according to the unacceptable working condition of the occurrence of the resonance, or outputting the control parameters of the harmonic control strategy of the flexible direct-current transmission system according to the acceptable working condition of the occurrence of the resonance;
the working condition under the operation mode in the harmonic control strategy of the flexible direct current transmission system is an operation working condition formed by combining an operation mode of a power grid and a connection mode of the power grid, beta is a phase angle margin, and K is an amplitude margin coefficient.
The invention also provides a 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 harmonic control strategy evaluation method for the flexible direct current power transmission system according to instructions in the program code.
According to the technical scheme, the embodiment of the invention has the following advantages:
1. the harmonic control strategy evaluation method of the flexible direct current transmission system obtains the amplitude and the phase difference of any one operation condition of a processed power grid by obtaining and processing the flexible direct current alternating current impedance in the flexible direct current transmission system and the alternating current power grid impedance in the power grid alternating current system, and evaluates whether the flexible direct current transmission system contains resonance under the harmonic control strategy according to a judgment principle; the power grid alternating current system operation working conditions comprise hundreds to thousands of working conditions, the harmonic control strategy evaluation method of the flexible direct current transmission system can evaluate the resonance risks of hundreds to thousands of operation working conditions within minute-scale time, the workload is greatly simplified, whether the harmonic control strategy meets the requirements of the flexible direct current transmission system or not is gradually known, so that the stable operation of the flexible direct current transmission system is improved, and the technical problems that the existing flexible direct current transmission and the connected power grid can generate high-frequency resonance, the high-frequency resonance influences the safe operation stability of the power grid and the safety of power equipment in the power grid are solved.
2. The harmonic control strategy evaluation system of the flexible direct current transmission system obtains and obtains flexible direct current alternating current impedance in the flexible direct current transmission system and alternating current power grid impedance in a power grid alternating current system through a data obtaining unit, a data processing unit processes the flexible direct current alternating current impedance and the alternating current power grid impedance, and an evaluation unit judges and evaluates whether the flexible direct current transmission system has resonance under the harmonic control strategy according to the processed data; the power grid alternating current system operation working conditions comprise hundreds to thousands of working conditions, the harmonic control strategy evaluation method of the flexible direct current transmission system can evaluate the resonance risks of hundreds to thousands of operation working conditions within minute-scale time, the workload is greatly simplified, whether the harmonic control strategy meets the requirements of the flexible direct current transmission system or not is gradually known, so that the stable operation of the flexible direct current transmission system is improved, and the technical problems that the existing flexible direct current transmission and the connected power grid can generate high-frequency resonance, the high-frequency resonance influences the safe operation stability of the power grid and the safety of power equipment in the power grid are 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 harmonic control strategy evaluation method for a flexible direct current power transmission system according to an embodiment of the present invention.
Fig. 2 is a block diagram of a harmonic control strategy evaluation system of a flexible direct current power transmission system according to an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a conventional flexible direct current transmission access power grid.
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.
In the present embodiment, the explanation of terms: the flexible Direct Current Transmission is High Voltage Direct Current Transmission (VSC-HVDC) based on a Voltage Source Converter, is a novel Transmission technology based on the Voltage Source Converter, a self-turn-off device and a Pulse Width Modulation (PWM) technology, and has the advantages of being capable of supplying power to a passive network, avoiding phase change failure, avoiding communication among Converter stations, being easy to form a multi-terminal Direct Current system and the like.
As the water energy resources in China are mainly concentrated in the southwest region, the electric load is relatively concentrated in the eastern region. The method is an objective requirement for optimizing resource allocation and solving the problem of reverse distribution of energy and power load in China in order to implement long-distance and large-capacity 'West electric and east electric transmission', and is an important measure for changing resource advantages of underdeveloped areas in the West into economic advantages and promoting the common development of economy in the West and east areas. The direct current transmission adopts a power electronic conversion technology, clean water and electricity at a transmitting end are converted into high-voltage direct current, and the high-voltage direct current is transmitted to a receiving end load center through a long-distance overhead line, so that the power transmission efficiency is high, the cost is saved, and a power transmission corridor is formed, and the main mode of 'west-east power transmission'.
As shown in fig. 3, fig. 3 is a schematic structural diagram of a conventional flexible dc transmission access grid. The power grid comprises a transmitting end power grid, a receiving end power grid and a flexible direct current transmission system arranged between the transmitting end power grid and the receiving end power grid, and the transmitting end power grid transmits power to the receiving end power grid through a power transmission line. Wherein the converter is arranged on the flexible direct current transmission system. When the impedance matching between the flexible direct current transmission system and the transmission end power grid or the receiving end power grid is not correct, high-frequency resonance may be generated, and the high-frequency resonance may threaten the safe and stable operation of the power system and the flexible direct current transmission system in the power grid.
Therefore, the embodiment of the application provides a harmonic control strategy evaluation method, system and device for a flexible direct current transmission system, and is used for solving the technical problems that the existing flexible direct current transmission and the access power grid generate high-frequency resonance, and the high-frequency resonance affects the safe operation stability of the power grid and the safety of power equipment in the power grid.
The first embodiment is as follows:
fig. 1 is a flowchart illustrating steps of a harmonic control strategy evaluation method for a flexible direct current power transmission system according to an embodiment of the present invention.
As shown in fig. 1, an embodiment of the present invention provides a method for evaluating a harmonic control strategy of a flexible direct current power transmission system, which is used for evaluating a harmonic control strategy of the flexible direct current power transmission system, and includes the following steps:
s1, acquiring flexible direct current alternating current impedance in a flexible direct current power transmission system and alternating current power grid impedance of each operation mode of the flexible direct current power transmission system accessing an electric network point;
s2, obtaining the amplitude A of the flexible direct current alternating current impedance and the phase phi of the flexible direct current alternating current impedance according to the flexible direct current alternating current impedance and the impedance of the alternating current power gridAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the subtraction of the impedance phase of the alternating current power grid and the flexible direct current impedance phase of each operation mode to obtain the phase difference phi between the flexible direct current impedance and the impedance of the alternating current power grid;
s3, if KB is greater than A and phi is greater than 180 degrees + beta or phi < -180 degrees + beta in any one operation working condition, the operation working condition in the harmonic control strategy of the flexible direct-current power transmission system contains resonance;
the working condition under the operation mode in the harmonic control strategy of the flexible direct current transmission system is an operation working condition formed by combining an operation mode of a power grid and a connection mode of the power grid, beta is a phase angle margin, and K is an amplitude margin coefficient.
It should be noted that, in the flexible direct current transmission system, the harmonic control strategy is mainly to reduce or eliminate harmonics in the output current voltage of the flexible direct current transmission system, and avoid the harmonic causing resonance to cause unstable and safe operation of the power grid and damage to the power equipment in the power grid. The harmonic control strategy evaluation method of the flexible direct current transmission system is mainly used for evaluating whether a harmonic control strategy in the flexible direct current transmission system can control resonance of the flexible direct current transmission system or not, so that a power grid can stably and safely operate, and safety of power equipment in the power grid is ensured.
In S1 of the embodiment of the present invention, according to the harmonic control strategy of the flexible dc power transmission system, the impedance of the flexible dc power transmission system under the harmonic control strategy may be confirmed by using offline simulation or real-time simulation scanning. The frequency of the flexible direct current and alternating current impedance is below 2500Hz, and the resolution of the frequency of the flexible direct current and alternating current impedance is not more than 1 Hz. In this embodiment, if there are other devices (such as a transformer and a voltage divider) in the flexible dc power transmission system besides the converter station, the flexible dc ac impedance is a total impedance of the flexible dc power transmission system and the other devices connected in parallel, and is also a flexible dc ac impedance of the converter station in the flexible dc power transmission system. And applying the flexible direct current and alternating current impedance of the flexible direct current converter station to carry out subsequent analysis.
It should be noted that the real-time simulation technology may be a simulation technology of a "modular multilevel flexible direct-current transmission digital-analog hybrid real-time simulation technology" disclosed in "power automation equipment" of 2 nd of 2013, or may be other real-time simulation or offline simulation technologies capable of obtaining the impedance of the flexible direct-current transmission system through scanning.
In S1 of the embodiment of the present invention, according to the data of the power grid operation mode, impedance of the flexible dc power transmission system accessing the power grid ac system is analyzed by using mature commercial software such as NimScan, and is recorded as ac power grid impedance. The harmonic control strategy evaluation method for the flexible direct current transmission system is used for analyzing the influence of different wiring modes and different operation modes (large, small, big and small) on the impedance of the power grid home system, so that the harmonic control strategy evaluation method for the flexible direct current transmission system is used for independently analyzing the resonance under different working conditions.
The operation mode data is data of an operation mode of the power grid ac system, and the data includes data contents such as a grid structure, a load, a power flow, and the like of the ac power grid. And giving impedance curves under different frequency bands according to the operation condition of each combination. Generally, the ac system impedance in each connection mode is analyzed for each operation mode. For the connection mode, besides the full-connection operation mode, the impedance characteristic of an alternating current power grid when part of the alternating current lines are out of operation due to faults is also considered, and the considered connection mode covers all possible connection modes of the near-region alternating current lines until only the remaining alternating current lines operate in the alternating current system of the power grid.
In the embodiment, the flexible direct current and alternating current impedance and the alternating current power grid impedance have the same frequency resolution, the same resolution avoids uncertain factors, and the evaluation accuracy is improved.
In S2 of the embodiment of the present invention, the flexible dc-ac impedance and the ac grid impedance obtained in S1 are processed to obtain the flexible dc-ac impedance amplitude a and the flexible dc-ac impedance phase phiAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBAnd calculating the phase difference between the flexible direct current alternating current impedance and the alternating current power grid impedance.
It should be noted that the ac grid impedance and the flexible dc ac impedance are both composed of amplitude and phase at each frequency.
In S3 of the embodiment of the present invention, it is mainly evaluated according to a judgment principle whether the flexible direct current transmission system has resonance under any one operation condition under a harmonic control strategy. The margin coefficient of the amplitude is
Wherein C is the amplitude margin. In the present embodiment, the amplitude margin may preferably be 3, and the phase angle margin may preferably be 5. The amplitude margin and the phase angle margin are set values, the unit of the amplitude margin is decibel, and the unit of the phase angle margin is degree.
It should be noted that the judgment principle is that KB > a in any one operation condition, and phi >180 ° + beta or phi < -180 ° + beta, the operation condition in the harmonic control strategy of the flexible direct current transmission system contains resonance; otherwise, the harmonic control strategy of the flexible direct current transmission system has no resonance under the operation condition, and control parameters in the harmonic control strategy of the flexible direct current transmission system are output. Because the operation working conditions of the power grid alternating current system contain hundreds to thousands of working conditions, the harmonic control strategy evaluation method of the flexible direct current transmission system can realize the evaluation of the resonance risks of hundreds to thousands of operation working conditions within minute-level time, greatly simplify the workload, improve the efficiency of the evaluation resonance control strategy, gradually know whether the harmonic control strategy meets the requirements of the flexible direct current transmission system, and if the harmonic control strategy parameters are not optimized again, improve the stable operation of the flexible direct current transmission system.
According to the harmonic control strategy evaluation method for the flexible direct current transmission system, the amplitude and the phase difference of any one operation condition of a processed power grid are obtained by obtaining and processing the flexible direct current alternating current impedance in the flexible direct current transmission system and the alternating current power grid impedance in the power grid alternating current system, and whether the flexible direct current transmission system has resonance under the harmonic control strategy is evaluated according to a judgment principle; the power grid alternating current system operation working conditions comprise hundreds to thousands of working conditions, the harmonic control strategy evaluation method of the flexible direct current transmission system can evaluate the resonance risks of hundreds to thousands of operation working conditions within minute-scale time, the workload is greatly simplified, whether the harmonic control strategy meets the requirements of the flexible direct current transmission system or not is gradually known, so that the stable operation of the flexible direct current transmission system is improved, and the technical problems that the existing flexible direct current transmission and the connected power grid can generate high-frequency resonance, the high-frequency resonance influences the safe operation stability of the power grid and the safety of power equipment in the power grid are solved.
In an embodiment of the invention, the harmonic control strategy evaluation method for the flexible direct current transmission system further comprises the steps of judging whether the working condition of resonance generation is acceptable;
if the working condition of the resonance is not acceptable, the harmonic control strategy of the flexible direct current transmission system needs to be optimized, and the optimized harmonic control strategy of the flexible direct current transmission system executes the steps S1 to S3 again until the working condition of the resonance is acceptable or no resonance exists in the flexible direct current transmission system;
and if the resonance working condition can be accepted, outputting the control parameters of the harmonic control strategy of the flexible direct current transmission system.
It should be noted that whether the operation condition of the resonance is acceptable is usually determined by the grid dispatching principle, for example, the fault is not acceptable due to an N-1 fault (i.e. a fault of any single element in the grid ac system, such as an ac return line exit, a power tower collapse, etc.); and as another example, the occurrence of resonance in a service mode of the grid ac system is unacceptable.
Example two:
fig. 2 is a block diagram of a harmonic control strategy evaluation system of a flexible direct current power transmission system according to an embodiment of the present invention.
As shown in fig. 2, an embodiment of the present invention further provides a flexible direct current power transmission system harmonic control strategy evaluation system, which is used for evaluating a flexible direct current power transmission system harmonic control strategy, and includes a data obtaining unit 10, a data processing unit 20, an evaluation unit 30, and a determination unit 40:
the data acquisition unit 10 is configured to acquire a flexible direct-current alternating-current impedance in the flexible direct-current power transmission system and an alternating-current power grid impedance of each operation mode in which the flexible direct-current power transmission system accesses an electrical grid point;
a data processing unit 20 for obtaining the flexible DC/AC impedance amplitude A and the flexible DC/AC impedance phase phi according to the flexible DC/AC impedance and the AC grid impedanceAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the subtraction of the impedance phase of the alternating current power grid and the flexible direct current impedance phase of each operation mode to obtain the phase difference phi between the flexible direct current impedance and the impedance of the alternating current power grid;
the evaluation unit 30 is used for evaluating the operating condition of the harmonic control strategy of the flexible direct current transmission system according to KB > A in any operating condition and phi >180 degrees + beta or phi < -180 degrees + beta, wherein the operating condition contains resonance;
the judging unit 40 is configured to judge that the harmonic control strategy of the flexible direct current transmission system needs to be optimized according to the unacceptable working condition of the occurrence of resonance, or output a control parameter of the harmonic control strategy of the flexible direct current transmission system according to the acceptable working condition of the occurrence of resonance;
the working condition under the operation mode in the harmonic control strategy of the flexible direct current transmission system is an operation working condition formed by combining an operation mode of a power grid and a connection mode of the power grid, beta is a phase angle margin, and K is an amplitude margin coefficient.
It should be noted that, the units in the system of the second embodiment are correspondingly arranged in the steps in the method of the first embodiment, and the details of the steps are described in detail in the method of the first embodiment, so that the details of the units in the system of the second embodiment are not described herein.
According to the harmonic control strategy evaluation system of the flexible direct current transmission system, the flexible direct current alternating current impedance in the flexible direct current transmission system and the alternating current power grid impedance in the power grid alternating current system are obtained through the data obtaining unit, the data processing unit processes the flexible direct current alternating current impedance and the alternating current power grid impedance, and the evaluation unit judges and evaluates whether the flexible direct current transmission system has resonance under the harmonic control strategy or not according to the processed data; the power grid alternating current system operation working conditions comprise hundreds to thousands of working conditions, the harmonic control strategy evaluation method of the flexible direct current transmission system can evaluate the resonance risks of hundreds to thousands of operation working conditions within minute-scale time, the workload is greatly simplified, whether the harmonic control strategy meets the requirements of the flexible direct current transmission system or not is gradually known, so that the stable operation of the flexible direct current transmission system is improved, and the technical problems that the existing flexible direct current transmission and the connected power grid can generate high-frequency resonance, the high-frequency resonance influences the safe operation stability of the power grid and the safety of power equipment in the power grid are solved.
Example three:
the embodiment of the invention provides 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 harmonic control strategy evaluation method of the flexible direct current power transmission system according to 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 harmonic control strategy evaluation method for the flexible direct current power transmission system according to the instructions in the program code. Alternatively, the processor, when executing the computer program, implements the functions of the modules/units in the system/apparatus embodiments described above, such as the functions of the units 10 to 40 shown in fig. 2.
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, systems 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 and method may be implemented in other ways. For example, the above-described system embodiments are merely illustrative, and for example, the division of the units is only one logical functional 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, systems 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 harmonic control strategy evaluation method of a flexible direct current transmission system is used for evaluating a harmonic control strategy of the flexible direct current transmission system, and is characterized by comprising the following steps:
s1, acquiring flexible direct current alternating current impedance in a flexible direct current power transmission system and alternating current power grid impedance of each operation mode of the flexible direct current power transmission system accessing an electric network point;
s2, obtaining a flexible direct current alternating current impedance amplitude A and a flexible direct current alternating current impedance phase phi according to the flexible direct current alternating current impedance and the alternating current power grid impedanceAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the phase difference phi between the flexible direct current alternating current impedance and the alternating current power grid impedance by subtracting the flexible direct current alternating current impedance phase from the alternating current power grid impedance phase of each operation mode;
s3, if KB is greater than A and phi is greater than 180 degrees + beta or phi < -180 degrees + beta in any one operation working condition, the operation working condition in the harmonic control strategy of the flexible direct-current power transmission system contains resonance;
the working condition under the operation mode in the harmonic control strategy of the flexible direct current transmission system is an operation working condition formed by combining an operation mode of a power grid and a connection mode of the power grid, beta is a phase angle margin, and K is an amplitude margin coefficient.
2. The harmonic control strategy evaluation method of the flexible direct current transmission system according to claim 1, further comprising determining whether a resonance condition is acceptable;
if the working condition of the resonance is not acceptable, the harmonic control strategy of the flexible direct current transmission system needs to be optimized, and the optimized harmonic control strategy of the flexible direct current transmission system executes the steps S1 to S3 again until the working condition of the resonance is acceptable or no resonance exists in the flexible direct current transmission system;
and if the resonance working condition can be accepted, outputting the control parameters of the harmonic control strategy of the flexible direct current transmission system.
3. The harmonic control strategy evaluation method of claim 1, wherein in step S1, the flexible dc ac impedance is obtained by scanning the flexible dc power transmission system using off-line simulation or real-time simulation.
4. The harmonic control strategy evaluation method of claim 1, wherein the flexible direct current alternating current impedance is a flexible direct current alternating current impedance of a converter station in the flexible direct current transmission system.
5. The harmonic control strategy evaluation method of the flexible direct current transmission system according to claim 1, wherein according to the operation modes of the power grid, in step S1, the alternating current grid impedance of each operation mode at the point where the flexible direct current transmission system is connected to the power grid is analyzed by using NimScan.
6. The flexible direct current transmission system harmonic control strategy evaluation method according to claim 1, characterized in that the flexible direct current alternating current impedance has the same frequency resolution as the alternating current grid impedance.
7. The harmonic control strategy evaluation method of claim 1, wherein the amplitude margin coefficient is
Wherein C is the amplitude margin.
8. The flexible direct current transmission system harmonic control strategy evaluation method of claim 7, wherein the amplitude margin is 3 and the phase angle margin is 5.
9. A harmonic control strategy evaluation system of a flexible direct current transmission system is used for evaluating a harmonic control strategy of the flexible direct current transmission system and is characterized by comprising a data acquisition unit, a data processing unit, an evaluation unit and a judgment unit;
the data acquisition unit is used for acquiring the flexible direct current alternating current impedance in the flexible direct current transmission system and the alternating current power grid impedance of each operation mode of the flexible direct current transmission system accessing the power grid point;
the data processing unit is used for obtaining a flexible direct current alternating current impedance amplitude A and a flexible direct current alternating current impedance phase phi according to the flexible direct current alternating current impedance and the alternating current power grid impedanceAAmplitude B of the impedance of the AC mains and phase phi of the impedance of the AC mainsBCalculating the phase difference phi between the flexible direct current alternating current impedance and the alternating current power grid impedance by subtracting the flexible direct current alternating current impedance phase from the alternating current power grid impedance phase of each operation mode;
the evaluation unit is used for determining whether the operating condition in the harmonic control strategy of the flexible direct current transmission system contains resonance according to KB > A and phi >180 DEG + beta or phi < -180 DEG + beta in any operating condition;
the judging unit is used for judging that the harmonic control strategy of the flexible direct-current transmission system needs to be optimized according to the unacceptable working condition of the occurrence of the resonance, or outputting the control parameters of the harmonic control strategy of the flexible direct-current transmission system according to the acceptable working condition of the occurrence of the resonance;
the working condition under the operation mode in the harmonic control strategy of the flexible direct current transmission system is an operation working condition formed by combining an operation mode of a power grid and a connection mode of the power grid, beta is a phase angle margin, and K is an amplitude margin coefficient.
10. An 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 configured to execute the method for harmonic control strategy evaluation of a flexible direct current power transmission system according to any of claims 1-8 according to instructions in the program code.
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| CN112803468B (en) * | 2021-01-20 | 2023-03-10 | 中国南方电网有限责任公司 | AC/DC complementary resonance suppression control method and device |
| CN112952889B (en) * | 2021-03-11 | 2023-06-06 | 南方电网科学研究院有限责任公司 | Optimizing method and device for virtual power grid self-adaptive control strategy and terminal equipment |
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