CN111913039A - Background harmonic voltage calculation method and device of alternating current filter - Google Patents
Background harmonic voltage calculation method and device of alternating current filter Download PDFInfo
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Abstract
The invention provides a background harmonic voltage calculation method and a background harmonic voltage calculation device for an alternating current filter, wherein the method comprises the steps of obtaining site voltage waveforms, site current waveforms and alternating current power grid data of selected substations; analyzing the station voltage waveform and the station current waveform of each selected transformer station by a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period; calculating the equivalent harmonic impedance of each selected substation according to the alternating current power grid data; calculating initial background harmonic voltage of each selected transformer substation in each time period according to each harmonic voltage, each harmonic current and equivalent harmonic impedance; and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter. According to the method, a plurality of selected substations are selected as the test points, the maximum value is calculated according to the data of each test point and is selected as the background harmonic voltage, and the design margin of the alternating current filter can be guaranteed.
Description
Technical Field
The invention relates to the technical field of filter design, in particular to a background harmonic voltage calculation method and device of an alternating current filter, computer equipment and a computer readable storage medium.
Background
The ac filter is a device commonly used and critical in the power grid, and it is very important to design an appropriate ac filter. The purpose of the ac filter is to limit the flow of harmonic currents generated by the dc transmission system into the ac system to prevent them from affecting the normal operation of other equipment in the ac system. According to the basic principle of who produced governance, the power quality problem generated by the alternating current system should be solved by the alternating current system, while the direct current system only solves the power quality problem caused by the harmonic current of itself. The ac filter setting is a key parameter in the design of the ac filter, and when calculating the ac filter setting, the influence of the grid background harmonic on the ac filter is usually considered.
The power grid background harmonic is usually described by a harmonic voltage source, and the background harmonic voltage is an important characteristic parameter in harmonic research, which is influenced by the penetration of harmonic voltage of a superior power grid on one hand and other harmonic sources of a present power grid on the other hand.
In the design of the alternating current filter, the power grid background harmonic wave is usually measured by a real measurement method. Because the direct current project is not put into operation, the background harmonic voltage of the direct current converter station cannot be obtained, at present, the harmonic voltage of a bus of a near-zone transformer substation of the direct current converter station is usually adopted as the background harmonic voltage, but after the converter station is put into operation, the alternating current system network structure of the near-zone transformer substation of the direct current converter station can be changed, so that the harmonic voltage of the near-zone transformer substation is changed; and the harmonic source of the near-area substation is used as the harmonic source of the far-end (namely, the direct current converter station), and the distribution of the harmonic source is different due to different grid structures of the power grids in the areas with different power grid characteristics, so that the harmonic voltage of the near-area substation cannot represent the harmonic source of the direct current converter station, and the harmonic voltage has larger difference. Therefore, the background harmonic voltage of the direct current converter station is difficult to accurately measure by the conventional background harmonic voltage measuring method, so that the fixed value of the alternating current filter cannot be accurately calculated.
Disclosure of Invention
In view of this, the present invention provides a method and an apparatus for calculating a background harmonic voltage of an ac filter, so as to solve the technical problem that the background harmonic voltage of a dc converter station is difficult to be accurately measured by the conventional background harmonic voltage measuring method, and thus the constant value of the ac filter cannot be accurately calculated.
In order to achieve the purpose, the invention provides the following technical scheme:
the embodiment of the invention provides a method for calculating background harmonic voltage of an alternating current filter, wherein the alternating current filter is arranged in a direct current converter station and comprises the following steps:
acquiring station voltage waveforms, station current waveforms and alternating current power grid data of all selected substations; wherein the selected substation is determined according to the position of the DC converter station;
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
calculating the equivalent harmonic impedance of each time of each selected transformer substation according to the alternating current power grid data;
calculating initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
Further, the air conditioner is provided with a fan,
the step of calculating the initial background harmonic voltage of each selected substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance comprises:
calculating the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
Further, the air conditioner is provided with a fan,
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current in each time period, wherein the step comprises the following steps of:
and analyzing the site voltage waveform and the site current waveform of each selected transformer substation by adopting a fast Fourier decomposition method to obtain each harmonic voltage and each harmonic current in each time period.
Further, the air conditioner is provided with a fan,
before the step of obtaining the station voltage waveform, the station current waveform and the alternating current power grid data of each selected transformer substation, the method comprises the following steps:
and selecting a transformer substation which is directly connected with the direct current converter station or has an electrical distance smaller than a preset distance from the direct current converter station as the selected transformer substation by taking the direct current converter station as a center, wherein the number of the selected transformer substations is three or more.
Further, the air conditioner is provided with a fan,
and the site voltage waveform and the site current waveform of each selected substation are acquired in a fault recording mode.
Further, the air conditioner is provided with a fan,
the site voltage waveform and the site current waveform of each of the selected substations are continuously collected, wherein the continuous collection period is at least 7 days, and the time interval of each collection is less than or equal to 1 hour.
The embodiment of the invention provides a background harmonic voltage calculation device of an alternating current filter, wherein the alternating current filter is arranged in a direct current converter station and comprises the following components:
the information acquisition module is used for acquiring the station voltage waveform, the station current waveform and the alternating current power grid data of each selected transformer station; wherein the selected substation is determined according to the position of the DC converter station;
the waveform analysis module is used for analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
the impedance calculation module is used for calculating the equivalent harmonic impedance of each selected transformer substation according to the alternating current power grid data;
the initial background harmonic voltage calculation module is used for calculating the initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and the background harmonic voltage selection module is used for comparing each initial background harmonic voltage and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
Further, the air conditioner is provided with a fan,
the initial background harmonic voltage calculation module is further configured to calculate the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
The embodiment of the invention provides computer equipment, which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein the processor executes the program to realize the following steps:
acquiring station voltage waveforms, station current waveforms and alternating current power grid data of all selected substations; wherein the selected substation is determined according to the position of the DC converter station;
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
calculating the equivalent harmonic impedance of each time of each selected transformer substation according to the alternating current power grid data;
calculating initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps of:
acquiring station voltage waveforms, station current waveforms and alternating current power grid data of all selected substations; wherein the selected substation is determined according to the position of the DC converter station;
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
calculating the equivalent harmonic impedance of each time of each selected transformer substation according to the alternating current power grid data;
calculating initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
According to the background harmonic voltage calculation method and device of the alternating current filter, the computer equipment and the computer readable storage medium, firstly, station voltage waveforms, station current waveforms and alternating current power grid data of selected substations are obtained; the selected transformer substation is determined according to the position of the direct current converter station; then, analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period; calculating the equivalent harmonic impedance of each selected substation according to the alternating current power grid data; calculating initial background harmonic voltage of each selected transformer substation in each time period according to each harmonic voltage, each harmonic current and equivalent harmonic impedance; and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter. According to the method, a plurality of alternating current substations (namely selected substations) are selected as background harmonic test points, the stability of the network structure of an alternating current system after the direct current converter station is put into operation can be guaranteed to the greatest extent, so that the accuracy of test data of the test points is guaranteed, then the initial calculation background harmonic voltage is calculated according to the test data of the test points, and the design margin of an alternating current filter can be effectively guaranteed by selecting the maximum value as the background harmonic voltage.
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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, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of an application environment of a background harmonic voltage calculation method of an AC filter according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of AC filter constant value calculation according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating the relationship between background harmonics and harmonic currents according to an embodiment of the present invention;
FIG. 4 is a flow chart of a method for calculating a background harmonic voltage of an AC filter according to an embodiment of the present invention;
fig. 5 is a connection diagram of a dc converter station in an embodiment of the invention;
FIG. 6 is a schematic structural diagram of a background harmonic voltage calculation apparatus of an AC filter according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a computer device in an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all 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 order to explain the present invention in more detail, a method, an apparatus, a computer device, and a computer readable storage medium for calculating a background harmonic voltage of an ac filter according to the present invention are described in detail below with reference to the accompanying drawings.
The method is applied to the terminal 102 in fig. 1, the terminal may be a personal computer, a notebook computer, etc., the terminal 102 is in communication connection with the detection device 104, and the detection device 104 may be disposed in each selected substation for detecting or recording the voltage of the selected substation, the current waveform flowing into the substation, and the ac power grid data. Alternatively, the detection device 104 may be a waveform collector, a fault recorder, or the like.
When the terminal 102 and the detection device 104 are connected by a local interface, the detection device 104 may send the acquired voltage waveform, current waveform and ac power grid data to the terminal 102. In addition, the terminal 102 may also obtain the voltage waveform, the current waveform, and the ac grid data of each selected substation in the detection device 104 through the command.
The calculation model of the ac filter constant is shown in fig. 2 to 3. Ub is the background harmonic. The constant value calculation corresponds to the superposition of two state loops. When considering the background harmonics, SW1 and SW3 are closed, when the filter impedance is in series relationship with the system harmonic impedance. When harmonic currents are considered, SW2 and SW3 are closed and the filter impedance is in a parallel relationship with the system impedance. Both in parallel and in series, the maximum voltage and current stresses on the ac filter device can be obtained at the maximum resonance. From the above analysis, the parallel connection relationship between the ac filter and the ac system has an influence on both the performance and the constant value of the ac filter, and the series connection relationship between the ac filter and the ac system has an influence mainly on the constant value. Therefore, it is important to calculate the background harmonic voltage when calculating the ac filter constant value. In addition, the background harmonic refers to the harmonic of the ac power grid itself, and the harmonic current is the harmonic current generated by the dc converter station, where the relationship between the background harmonic and the harmonic current is shown in fig. 3.
In one embodiment, as shown in fig. 4, a method for calculating a background harmonic voltage of an ac filter is provided, which is described by taking the method as an example for being applied to the terminal in fig. 1, where the ac filter is provided in a dc converter station, and includes the following steps:
step S402, acquiring station voltage waveforms, station current waveforms and alternating current power grid data of each selected transformer substation; the selected transformer substation is determined according to the position of the direct current converter station;
the ac filter is installed in the dc converter station (which is usually in the plan and not yet established), so the substation (i.e. the selected substation) is selected as the test point centered on the location of the dc converter station when calculating the parameter or factor (i.e. the background harmonic voltage) of the ac filter setting. Optionally, the number of the selected substations may be one or more, and in order to ensure the accuracy of the background harmonic voltage calculated later, at least 3 selected substations are usually selected as the test points.
In one embodiment, the step of obtaining the site voltage waveform, the site current waveform and the ac grid data for each selected substation is preceded by the steps of: and selecting a transformer substation which is directly connected with the direct current converter station or has the electrical distance less than the preset distance from the direct current converter station as a selected transformer substation by taking the direct current converter station as a center, wherein the number of the selected transformer substations is three or more.
Specifically, when determining the selected substation, generally, a connection diagram of the dc converter station (as shown in fig. 5) is used as a reference, the dc converter station (i.e., the newly-built station in fig. 5) is used as a center, and a substation directly connected to the dc converter station or electrically closer to the dc converter station is selected as the selected substation. Typically, the determination of the selected substation requires that at least one selected substation extend to the next ac substation node of the ac substation nodes directly connected to the dc converter station.
The preset distance is a value which can be preset, and the value can be selected according to the distance between the direct current converter station and other substations. In addition, the selected substation of choice is typically a 500kV alternating current substation. A plurality of selected substations are selected as test points, so that the measured data can be more accurate and fit with the actual situation.
And the site voltage waveform and the site current waveform are waveforms formed by voltage and current generated in the selected substation power grid. The alternating current power grid data refers to data related to an alternating current power grid in a selected transformer substation and mainly comprises generator data, transformer data, load data, line data, reactive compensation equipment data, power electronic equipment and the like.
In one embodiment, the site voltage waveform and the site current waveform of each selected substation are collected by fault recording.
The fault recording is a device or a system commonly used in the power system, and can automatically and accurately record the change conditions of various electrical quantities in the processes before and after the fault when the power system has the fault, and has important effects on analyzing and processing the accident, judging whether the protection acts correctly or not and improving the safe operation water level of the power system through the analysis and comparison of the electrical quantities. The most important function of the fault recorder is to record the waveform. In this embodiment, fault logging can be used to accurately record the site voltage and current waveforms for each selected substation.
In one embodiment, the site voltage and site current waveforms for each selected substation are continuously collected for a period of at least 7 days, with each collection occurring at a time interval of less than or equal to 1 hour.
Specifically, the harmonics and loads of the power grid no longer vary over time, and typically vary periodically by day, night, and week or even year, depending on the operating characteristics of the power grid. Therefore, in order to obtain accurate voltage waveforms and current waveforms, the harmonics of the selected substation are periodically collected, i.e., collected continuously in one collection period.
Optionally, the continuous acquisition period is at least 7 days. Since the load of the power system varies with the week, for example, the work days on monday to friday, the load on the office and the factory is large. And the saturday is the rest day, and the load of the entertainment place is large. That is, the load changes in one week, but the load change rule is basically consistent from week to week, so that 7 days can be selected as a continuous collection period.
In addition, the station voltage waveform and the station current waveform of the selected transformer substation can be continuously collected, or the collection time points can be selected in the whole collection period and collected at each collection time point. Wherein the collection time point is generally selected in units of one day (i.e., 24 hours), and the time interval between each collection is less than or equal to 1 hour. And the time length of each acquisition cannot be too short, at least more than 1S (namely, the time of single wave recording lasts at least 1S). Optionally, the period of acquisition should be a heavy duty period. In addition, the recording frequency is not less than 5 kHz.
Since periodic recording is performed for each selected substation, there are many or groups of site voltage waveforms and site current waveforms for each selected substation.
Step S404, analyzing the station voltage waveform and the station current waveform of each selected transformer substation by a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
in this embodiment, each site voltage waveform and site current waveform of each selected substation need to be analyzed to obtain each harmonic voltage and each harmonic current in each time period. Optionally, at least 25 th harmonic voltage and harmonic current data are required for each selected substation.
In an optional embodiment, the step of analyzing the site voltage waveform and the site current waveform of each selected substation by using a harmonic analysis method to obtain the harmonic voltages and harmonic currents of each time period includes:
and analyzing the site voltage waveform and the site current waveform of each selected transformer substation by adopting a fast Fourier decomposition method to obtain each harmonic voltage and each harmonic current in each time period.
Fast Fourier decomposition (FFT), which is a fast algorithm of discrete Fourier transform, is obtained by improving the algorithm of the discrete Fourier transform according to the characteristics of odd, even, imaginary, real and the like of the discrete Fourier transform. The FFT can quickly transform continuous site voltage waveforms and site current waveforms into discrete subharmonic voltages and subharmonic currents with a small amount of calculation.
Step S406, calculating equivalent harmonic impedance of each selected substation according to the alternating current power grid data;
step S408, calculating initial background harmonic voltage of each selected transformer substation in each time period according to each harmonic voltage, each harmonic current and equivalent harmonic impedance;
in one embodiment, the step of calculating the initial background harmonic voltage of each selected substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance comprises:
the initial background harmonic voltage was calculated using the following formula:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
Step S410, comparing each initial background harmonic voltage, and selecting the largest initial background harmonic voltage as the background harmonic voltage of the ac filter.
Optionally, the background harmonic voltage is calculated by the following formula:
wherein
Representing the background harmonic voltage of order n. The maximum value of the calculation results of a plurality of selected transformer substations is used as the background harmonic voltage of the alternating current filter, so that the design margin of the alternating current filter is fully ensured.
The background harmonic voltage calculation method of the alternating current filter in the embodiment of the invention comprises the steps of firstly, obtaining station voltage waveforms, station current waveforms and alternating current power grid data of selected substations; the selected transformer substation is determined according to the position of the direct current converter station; then, analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period; calculating the equivalent harmonic impedance of each selected substation according to the alternating current power grid data; calculating initial background harmonic voltage of each selected transformer substation in each time period according to each harmonic voltage, each harmonic current and equivalent harmonic impedance; and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter. According to the method, a plurality of alternating current substations (namely selected substations) are selected as background harmonic test points, the stability of the network structure of an alternating current system after the direct current converter station is put into operation can be guaranteed to the greatest extent, so that the accuracy of test data of the test points is guaranteed, then the initial calculation background harmonic voltage is calculated according to the test data of the test points, and the design margin of an alternating current filter can be effectively guaranteed by selecting the maximum value as the background harmonic voltage.
The above embodiments of the present disclosure describe a method for calculating a background harmonic voltage of an ac filter in detail, and the method disclosed by the present disclosure can be implemented by various types of devices, so the present disclosure also discloses a device for calculating a background harmonic voltage of an ac filter corresponding to the above method, and the following detailed description is given to specific embodiments.
Referring to fig. 6, a background harmonic voltage calculation apparatus for an ac filter according to an embodiment of the present invention is disclosed, in which the ac filter is disposed in a dc converter station, and includes:
the information acquisition module 602 is configured to acquire a site voltage waveform, a site current waveform, and ac grid data of each selected substation; the selected transformer substation is determined according to the position of the direct current converter station;
the waveform analysis module 604 is configured to analyze the station voltage waveform and the station current waveform of each selected substation by using a harmonic analysis method to obtain each harmonic voltage and each harmonic current in each time period;
the impedance calculation module 606 is used for calculating the equivalent harmonic impedance of each selected substation according to the alternating current power grid data;
an initial background harmonic voltage calculation module 608, configured to calculate, according to each harmonic voltage, each harmonic current, and the equivalent harmonic impedance, each initial background harmonic voltage of each selected substation in each time period;
and a background harmonic voltage selection module 610, configured to compare each of the initial background harmonic voltages, and select a maximum initial background harmonic voltage as the background harmonic voltage of the ac filter.
In one embodiment, the initial background harmonic voltage calculation module is further configured to calculate the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
represents the m-th selectionHarmonic current of n-th order in a substation, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
In one embodiment, the waveform analysis module is further configured to analyze the site voltage waveform and the site current waveform of each selected substation by using a fast fourier decomposition method to obtain each harmonic voltage and each harmonic current in each time period.
In one embodiment, further comprising: and the selected substation selection module is used for selecting a substation which is directly connected with the direct current converter station or has an electrical distance smaller than a preset distance from the direct current converter station as a selected substation by taking the direct current converter station as a center, wherein the number of the selected substations is three or more.
In one embodiment, the site voltage waveform and the site current waveform of each selected substation are collected by fault recording.
In one embodiment, the site voltage and site current waveforms for each selected substation are continuously collected for a period of at least 7 days, with each collection occurring at a time interval of less than or equal to 1 hour.
For the specific definition of the background harmonic voltage calculation device of the ac filter, reference may be made to the above definition of the background harmonic voltage calculation method of the ac filter, and details are not described here. The various modules in the background harmonic voltage calculation device of the ac filter described above may be implemented in whole or in part by software, hardware, and combinations thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
An embodiment of the present invention further provides a computer device, where the computer device may be a server, and an internal structure diagram of the computer device may be as shown in fig. 7. The computer device includes a processor, a memory, a network interface, and a database connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The database of the computer equipment is used for storing data of the resistance equivalent model and the equivalent submodel, and storing equivalent resistance, working resistance and contact resistance obtained in the process of executing calculation. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a background harmonic voltage calculation method of an alternating current filter.
Those skilled in the art will appreciate that the architecture shown in fig. 7 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In one embodiment, a computer device is provided, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the following steps when executing the computer program:
acquiring station voltage waveforms, station current waveforms and alternating current power grid data of all selected substations; wherein the selected substation is determined according to the position of the DC converter station;
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
calculating the equivalent harmonic impedance of each time of each selected transformer substation according to the alternating current power grid data;
calculating initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
In one embodiment, the processor, when executing the computer program, further performs the steps of: the step of calculating the initial background harmonic voltage of each selected substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance comprises:
calculating the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
Further, the air conditioner is provided with a fan,
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current in each time period, wherein the step comprises the following steps of:
and analyzing the site voltage waveform and the site current waveform of each selected transformer substation by adopting a fast Fourier decomposition method to obtain each harmonic voltage and each harmonic current in each time period.
Further, the air conditioner is provided with a fan,
before the step of obtaining the station voltage waveform, the station current waveform and the alternating current power grid data of each selected transformer substation, the method comprises the following steps:
and selecting a transformer substation which is directly connected with the direct current converter station or has an electrical distance smaller than a preset distance from the direct current converter station as the selected transformer substation by taking the direct current converter station as a center, wherein the number of the selected transformer substations is three or more.
Further, the air conditioner is provided with a fan,
and the site voltage waveform and the site current waveform of each selected substation are acquired in a fault recording mode.
Further, the air conditioner is provided with a fan,
the site voltage waveform and the site current waveform of each of the selected substations are continuously collected, wherein the continuous collection period is at least 7 days, and the time interval of each collection is less than or equal to 1 hour.
An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps: acquiring station voltage waveforms, station current waveforms and alternating current power grid data of all selected substations; wherein the selected substation is determined according to the position of the DC converter station; analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period; calculating the equivalent harmonic impedance of each time of each selected transformer substation according to the alternating current power grid data; calculating initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance; and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
In one embodiment, the computer program when executed by the processor further performs the steps of: the step of calculating the initial background harmonic voltage of each selected substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance comprises: calculating the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
In one embodiment, the computer program when executed by the processor further performs the steps of: analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current in each time period, wherein the step comprises the following steps of: and analyzing the site voltage waveform and the site current waveform of each selected transformer substation by adopting a fast Fourier decomposition method to obtain each harmonic voltage and each harmonic current in each time period.
In one embodiment, the computer program when executed by the processor further performs the steps of: before the step of obtaining the station voltage waveform, the station current waveform and the alternating current power grid data of each selected transformer substation, the method comprises the following steps: and selecting a transformer substation which is directly connected with the direct current converter station or has an electrical distance smaller than a preset distance from the direct current converter station as the selected transformer substation by taking the direct current converter station as a center, wherein the number of the selected transformer substations is three or more.
In one embodiment, the computer program when executed by the processor further performs the steps of: and the site voltage waveform and the site current waveform of each selected substation are acquired in a fault recording mode.
In one embodiment, the computer program when executed by the processor further performs the steps of: the site voltage waveform and the site current waveform of each of the selected substations are continuously collected, wherein the continuous collection period is at least 7 days, and the time interval of each collection is less than or equal to 1 hour.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for calculating background harmonic voltage of an alternating current filter, wherein the alternating current filter is arranged in a direct current converter station, is characterized by comprising the following steps:
acquiring station voltage waveforms, station current waveforms and alternating current power grid data of all selected substations; wherein the selected substation is determined according to the position of the DC converter station;
analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
calculating the equivalent harmonic impedance of each time of each selected transformer substation according to the alternating current power grid data;
calculating initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and comparing each initial background harmonic voltage, and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
2. The method of claim 1, wherein the step of calculating an initial background harmonic voltage for each of the selected substations at each time period from the harmonic voltage, the harmonic current and the equivalent harmonic impedance comprises:
calculating the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the equivalent harmonic impedance of the nth selected substation.
3. The method of claim 1, wherein the step of analyzing the site voltage waveform and the site current waveform of each of the selected substations by harmonic analysis to obtain the subharmonic voltages and subharmonic currents for each time period comprises:
and analyzing the site voltage waveform and the site current waveform of each selected transformer substation by adopting a fast Fourier decomposition method to obtain each harmonic voltage and each harmonic current in each time period.
4. A method according to any one of claims 1 to 3, wherein prior to the step of obtaining the site voltage waveform, site current waveform and ac grid data for each selected substation, comprising:
and selecting a transformer substation which is directly connected with the direct current converter station or has an electrical distance smaller than a preset distance from the direct current converter station as the selected transformer substation by taking the direct current converter station as a center, wherein the number of the selected transformer substations is three or more.
5. The method of claim 4, wherein the site voltage waveform and the site current waveform for each of the selected substations are collected by fault logging.
6. The method of claim 5, wherein the site voltage and site current waveforms of each of the selected substations are continuously collected over a period of at least 7 days, with each collection occurring at a time interval of less than or equal to 1 hour.
7. A background harmonic voltage calculation apparatus for an AC filter provided in a DC converter station, comprising:
the information acquisition module is used for acquiring the station voltage waveform, the station current waveform and the alternating current power grid data of each selected transformer station; wherein the selected substation is determined according to the position of the DC converter station;
the waveform analysis module is used for analyzing the station voltage waveform and the station current waveform of each selected transformer substation by adopting a harmonic analysis method to obtain each harmonic voltage and each harmonic current of each time period;
the impedance calculation module is used for calculating the equivalent harmonic impedance of each selected transformer substation according to the alternating current power grid data;
the initial background harmonic voltage calculation module is used for calculating the initial background harmonic voltage of each selected transformer substation in each time period according to the harmonic voltage, the harmonic current and the equivalent harmonic impedance;
and the background harmonic voltage selection module is used for comparing each initial background harmonic voltage and selecting the maximum initial background harmonic voltage as the background harmonic voltage of the alternating current filter.
8. The apparatus of claim 7, wherein the initial background harmonic voltage calculation module is further configured to calculate the initial background harmonic voltage using the following equation:
wherein the content of the first and second substances,
representing the initial background harmonic voltage of the mth selected substation n times, s representing the source of the mth equivalent harmonic,
represents the harmonic voltage of the nth order of the mth selected substation,
representing harmonic current of nth order of selected substation m, ZnmRepresenting the mth selected substationEquivalent harmonic impedance of order n.
9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the steps of the method of claims 1-6 are performed when the program is executed by the processor.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method of claims 1 to 6.
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