CN114123164A - Method and device for calculating short-circuit capacity of power system and terminal equipment - Google Patents
Method and device for calculating short-circuit capacity of power system and terminal equipment Download PDFInfo
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- CN114123164A CN114123164A CN202111184788.2A CN202111184788A CN114123164A CN 114123164 A CN114123164 A CN 114123164A CN 202111184788 A CN202111184788 A CN 202111184788A CN 114123164 A CN114123164 A CN 114123164A
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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
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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
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
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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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Abstract
The invention is suitable for the technical field of power supply systems, and provides a method, a device and a terminal device for calculating short-circuit capacity of a power system, wherein the method comprises the following steps: acquiring collected data at a target power supply point of the power system, wherein the collected data comprises voltage and current time domain data groups; acquiring a preset short circuit capacity from a preset value range according to a preset acquisition rule; aiming at each preset short circuit capacity, calculating an equivalent power supply voltage time domain data set according to the preset short circuit capacity, the voltage time domain data set and the current time domain data set; calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group; and obtaining the coefficient of variation with the minimum value, and taking the preset short-circuit capacity corresponding to the coefficient of variation with the minimum value as the short-circuit capacity of the power system. The method for calculating the short-circuit capacity of the power system, provided by the invention, can be suitable for the situation that the power system is not symmetrical, overcomes the sensitivity to three-phase unbalance, and improves the calculation accuracy of the short-circuit capacity.
Description
Technical Field
The invention belongs to the technical field of power systems, and particularly relates to a method and a device for calculating short-circuit capacity of a power system and terminal equipment.
Background
In an electric power system, the short-circuit capacity is the product of three-phase short-circuit current and voltage before short-circuit when a three-phase short-circuit occurs at a certain power supply point. The short-circuit capacity is an important basis for calculation of a power system protection setting value and calculation of a power quality assessment limit value, and is also an important parameter for power system fault analysis, design of a power quality management device and evaluation of an operation effect. Specifically, the short circuit capacity can reflect the level of short circuit current at the power supply point, the load capacity and the strength of the connection with the power supply of the power system.
The short circuit capacity is related to the capacity of the whole power system, and the level of the short circuit capacity changes along with the expansion of the capacity of the power system or the fitting of the operation mode of a power grid. Especially in the internal grid of the power consumer, the short circuit capacity is difficult to obtain accurately.
Conventionally, the calculation method of the short circuit capacity includes direct calculation and estimation using a voltage reactive fluctuation amount relationship. The direct calculation process comprises the steps of obtaining transient reactance of a generator, impedance of a power transmission line and impedance of a power supply transformer, converting the three parts of impedance to the voltage level of a power supply point, adding the three parts of impedance to obtain system impedance of the power supply point, and finally calculating short-circuit capacity by dividing the square of the nominal voltage of the power supply point by the system impedance. Due to the complex ring network structure on the side of the power system, the variable operation modes and the difficulty of accurately obtaining the parameters, the operation modes and the parameters obtained by a direct calculation method are inaccurate, the calculation amount is large, and the finally obtained calculation result has a large error.
The estimation of the relation of the voltage reactive fluctuation quantity comprises the steps of obtaining the voltage fluctuation generated on the system impedance when the load of the power supply point has reactive fluctuation, and estimating the operation short-circuit capacity of the system according to the relation between the voltage fluctuation quantity led out by the reactive fluctuation and the short-circuit capacity of the power supply point. However, in practical applications, the correspondence between the reactive power fluctuation and the voltage fluctuation amount is not only determined by the short-circuit capacity of the system, but also closely related to the operating voltage of the power supply point. The voltage of the power supply point deviates from the nominal voltage, and the voltage of the power supply point continuously changes along with the change of the load power, so that the operation voltage cannot be reasonably selected, and meanwhile, the problem of unbalance of the three-phase load power exists, and the accuracy of the short-circuit capacity calculated by the method is poor.
Disclosure of Invention
In view of this, embodiments of the present invention provide a method and an apparatus for calculating a short-circuit capacity of an electric power system, and a terminal device, which can improve the calculation accuracy of the short-circuit capacity of the electric power system.
A first aspect of an embodiment of the present invention provides a method for calculating a short-circuit capacity of an electric power system, including:
acquiring collected data at a target power supply point of a power system, wherein the collected data comprises a voltage time domain data set and a current time domain data set;
acquiring preset short-circuit capacity from a preset value range according to a preset acquisition rule, wherein the number of the preset short-circuit capacity is more than one;
aiming at each preset short circuit capacity, calculating an equivalent power supply voltage time domain data set according to the preset short circuit capacity, the voltage time domain data set and the current time domain data set;
calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group;
and acquiring the coefficient of variation with the minimum value, and taking the preset short-circuit capacity corresponding to the coefficient of variation with the minimum value as the short-circuit capacity of the power system.
A second aspect of an embodiment of the present invention provides an apparatus for calculating a short-circuit capacity of an electric power system, including:
the acquisition module of the collected data is used for acquiring the collected data at the target power supply point of the power system, and the collected data comprises a voltage time domain data set and a current time domain data set;
the system comprises a preset short-circuit capacity acquisition module, a short-circuit capacity acquisition module and a short-circuit capacity acquisition module, wherein the preset short-circuit capacity acquisition module is used for acquiring preset short-circuit capacity from a preset value range according to a preset acquisition rule, and the number of the preset short-circuit capacity is more than one;
the equivalent power supply voltage time domain data group calculating module is used for calculating an equivalent power supply voltage time domain data group according to each preset short circuit capacity and the voltage time domain data group and the current time domain data group;
the variation coefficient calculation module is used for calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group;
and the short-circuit capacity determining module is used for acquiring the variation coefficient with the minimum value and taking the preset short-circuit capacity corresponding to the variation coefficient with the minimum value as the short-circuit capacity of the power system.
A third aspect of the embodiments of the present invention provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the method when executing the computer program.
A fourth aspect of embodiments of the present invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the method as described above.
A fifth aspect of embodiments of the present invention provides a computer program product, which, when run on a terminal device, causes the electronic device to perform the steps of the method according to any one of the first aspect.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: the method for calculating the short-circuit capacity of the power system comprises the steps of acquiring collected data at a target power supply point of the power system, wherein the collected data comprise voltage and current time domain data groups; acquiring a preset short circuit capacity from a preset value range according to a preset acquisition rule; aiming at each preset short circuit capacity, calculating an equivalent power supply voltage time domain data set according to the preset short circuit capacity, the voltage time domain data set and the current time domain data set; calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group; and obtaining the coefficient of variation with the minimum value, and taking the preset short-circuit capacity corresponding to the coefficient of variation with the minimum value as the short-circuit capacity of the power system. The method for calculating the short-circuit capacity of the power system, provided by the embodiment of the invention, can be suitable for the situation that the power system is asymmetric, overcomes the sensitivity to three-phase imbalance and improves the calculation accuracy of the short-circuit capacity.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions 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 it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic flow chart illustrating an implementation of a method for calculating a short-circuit capacity of an electric power system according to an embodiment of the present invention;
fig. 2 is a schematic circuit structure diagram of an application of the short-circuit capacity calculation method for the power system according to the embodiment of the present invention;
FIG. 3 is a schematic diagram of an equivalent circuit applied to a method for calculating short-circuit capacity of an electrical power system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of collected data for one particular example provided by the present invention;
FIG. 5 is a graph illustrating voltage effects for a specific example provided by the present invention;
FIG. 6 is a diagram illustrating the results of a calculation according to a specific example of the present invention;
FIG. 7 is a diagram illustrating a calculation result of another specific example provided by the present invention
FIG. 8 is a schematic structural diagram of a short-circuit capacity calculation device of an electric power system according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a terminal device according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
Fig. 1 shows an implementation flow diagram of a method for calculating a short-circuit capacity of an electric power system according to an embodiment of the present invention.
Referring to fig. 1, a method for calculating a short-circuit capacity of an electrical power system according to an embodiment of the present invention may include steps S101 to S104.
S101: acquiring collected data at a target power supply point of a power system, wherein the collected data comprises a voltage time domain data set and a current time domain data set
Optionally, the voltage time domain data includes voltage time domain waveform data; the current time domain data includes current time domain waveform data.
Specifically, the voltage time domain data and the current time domain data are obtained by synchronous sampling.
Specifically, in order to ensure the accuracy of short-circuit capacity calculation, the voltage time domain data and the current time domain data need to be acquired in the normal production process of the load of the power system.
Fig. 2 is a schematic diagram illustrating a circuit configuration at a target power supply point according to an embodiment of the present invention. Referring to fig. 2, in one specific example, the target power supply point is a power supply point at the transformer low voltage main line. Acquiring voltage time domain data u (k) by a bus voltage transformer PT of a transformer low-voltage main incoming line; and acquiring current time domain data i (k) by a current transformer CT of a low-voltage main incoming line of the transformer. And k is a positive integer and is a sampling point of the voltage time domain data and the current time domain data.
Optionally, sampling frequency fSMore than or equal to 800 Hz; the sampling frequency can ensure that the sampling points of each cycle are not less than sixteen in the sampling of the commercial power, and voltage time domain waveform data and current time domain waveform data are conveniently restored according to the voltage time domain data and the current time domain data.
Optionally, the time period covered by the voltage time domain waveform data and the current time domain waveform data is not less than 1 second, for example, 1 second, 2 seconds, 5 seconds, or 10 seconds.
S102: and acquiring preset short-circuit capacity from a preset value range according to a preset acquisition rule, wherein the number of the preset short-circuit capacity is more than one.
Optionally, the preset short circuit capacity value range includes a continuous numerical value interval, and the preset rule includes selecting preset short circuit capacities of preset numbers at equal intervals.
Optionally, the preset short-circuit capacity value range includes a discrete value set, and the preset rule includes randomly obtaining a preset number of preset short-circuit capacities.
Optionally, the number of preset short circuit capacities is at least 500.
S103: and aiming at each preset short circuit capacity, calculating an equivalent power supply voltage time domain data set according to the preset short circuit capacity, the voltage time domain data set and the current time domain data set.
Fig. 3 shows an equivalent circuit diagram at a target power supply point provided by an embodiment of the present invention. Fig. 3 is a modification of fig. 2 according to thevenin's theorem. In FIG. 3, e (k) is the equivalent power supply voltage of the target power supply point, XSIs a system equivalent reactance, RSIs the system equivalent resistance, ZLFor load equivalent impedance, u (k) is voltage time domain data, and i (k) is current time domain data.
In some embodiments, as can be derived from fig. 3, the equivalent power supply voltage time domain waveform data calculation formula includes:
in the formula (1), e (k) is equivalent power supply voltage time domain data of a target power supply point at a sampling point k, u (k) is voltage time domain data of the target power supply point at the sampling point k, i (k) is current time domain data of the target power supply point at the sampling point k, i (k +1) is current time domain data of the target power supply point at the sampling point k +1, and f (k +1) is equivalent power supply voltage time domain data of the target power supply point at the sampling point kSFor sampling frequency, RSIs a system equivalent resistance, XSIs the system equivalent reactance, f0Is the fundamental frequency.
Optionally, f050Hz, the frequency of the grid.
In particular, the method comprises the following steps of,
wherein, UNFor nominal voltage at target supply point, SSCThe short circuit capacity at the target power supply point.
In some embodiments, R is takenS＝1/7XS，f050 Hz; the equivalent power supply voltage time domain waveform data calculation formula can be obtained by arranging:
and calculating first equivalent power supply voltage time domain waveform data corresponding to the first preset short-circuit capacity based on the formula (2).
Optionally, because the system equivalent impedance is far smaller than the system equivalent reactance, the influence on the calculation result is small, and the calculation of the system equivalent impedance can be ignored.
S104: and calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group.
In some embodiments, S104 may include S201 to S202.
S201: and calculating a voltage effective value data set aiming at each equivalent power supply voltage time domain data set.
In some embodiments, the voltage effective value data set is calculated based on a voltage effective value calculation formula;
the voltage effective value calculation formula comprises:
wherein E (M) is the mth voltage effective value, M is the number of the middle voltage effective values in the voltage effective value data,
and equivalent power supply voltage time domain data of each sampling point. In particular, the analysis interval of the voltage effective value is the grid (f)050 Hz). If the covering time of the voltage time domain data and the current time domain data is 1 second, M is 50.
Specifically, when f0When 50Hz, formula (3) can be arranged as:
s202: for each voltage valid value data set, a coefficient of variation is calculated.
In some embodiments, the coefficient of variation is calculated based on a coefficient of variation calculation formula;
the coefficient of variation calculation formula includes:
wherein, CVFor the coefficient of variation, e (m) is the voltage effective value data, σ (e (m)) is the standard deviation of the voltage effective value data, and μ (e (m)) is the expectation of the voltage effective value data.
S105: and acquiring the coefficient of variation with the minimum value, and taking the preset short-circuit capacity corresponding to the coefficient of variation with the minimum value as the short-circuit capacity of the power system.
In the present embodiment, since the voltage fluctuation in the grid system is small in a short time, the equivalent power supply voltage may be considered as a constant value in the acquisition time of the voltage time domain data and the current time domain data. Therefore, the equivalent power supply voltage calculated by the embodiment of the invention is close to the actual value, so that the finally determined error of the short-circuit capacity of the power system is small.
The method for calculating the short-circuit capacity of the power system, provided by the embodiment of the invention, applies thevenin equivalent theorem, deduces the functional relation between the equivalent power supply voltage and the short-circuit capacity based on the relation between the voltage, the current, the short-circuit capacity and the equivalent power supply voltage of a target power supply point, then takes the minimum variation coefficient as the target based on the short-term stability of the equivalent power supply voltage, and takes the corresponding short-circuit capacity as the short-circuit capacity of the power system when the short-term variation coefficient of the equivalent power supply voltage is the minimum. The calculation method provided by the embodiment of the invention is still suitable for the situation that the power system is asymmetric, can overcome the sensitivity to three-phase imbalance in the voltage reactive power fluctuation quantity relation estimation method, and has strong practicability and small error.
Further, in order to reduce the influence of the background unexpected conditions of the power system, such as a switching operation, a lightning overvoltage, and the like, on the calculation of the short-circuit capacity, the method provided by the embodiment of the invention may further include step S106.
S106: acquiring a preset number of acquired data, and respectively calculating the short circuit capacity corresponding to each acquired data to obtain the initial short circuit capacity of the preset number. And calculating an average value of the initial short-circuit capacity, and taking the average value as the short-circuit capacity of the power system.
Specifically, calculating the average value of the initial short circuit capacity includes: deleting the maximum initial short-circuit capacity and the minimum initial short-circuit capacity, calculating the average value of the residual initial short-circuit capacity, and taking the average value as the short-circuit capacity of the power system.
Specifically, the calculation formula for calculating the short-circuit capacity according to the initial short-circuit capacity is as follows:
wherein S isSCFor short circuit capacity, N is the number of initial short circuit capacities, SSC(pn) is the nth initial short circuit capacity, SSC,maxIs the maximum initial short-circuit capacity, SSC,minIs the minimum initial short circuit capacity.
Specifically, at least ten sets of current time domain data and voltage time domain data are obtained, and short circuit capacity is calculated respectively. The average value is calculated by dividing the maximum value and the minimum value of the short-circuit capacities, and the average value is used as the short-circuit capacity of the power system.
The method provided by the embodiment of the invention can reduce the deviation of background unexpected interference and power supply transient disturbance to short circuit capacity calculation by multiple calculation averaging steps, thereby further improving the accuracy of short circuit capacity calculation of the power system.
Taking an electric power system where an electric arc furnace is located as an example, the implementation process of the electric power system short-circuit capacity estimation method provided by the embodiment of the invention is further explained.
The bus of the electric arc furnace is a 33kV bus, the given short-circuit capacity is 777.85MVA, 12 groups of voltage time domain data and 12 groups of current time domain data are synchronously acquired on the 33kV bus alternating current transformer and the 33kV total incoming line current transformer respectively, the time covered by each group of data is 1 second, and the sampling frequency is 12.8 kHz.
Fig. 4 shows a bus voltage waveform diagram and a bus line current waveform diagram plotted from a first set of voltage time domain data and current time domain data therein.
In this example, the preset short-circuit capacity range of the 33kV bus power system is 400-1000MVA, and 601 preset short-circuit capacities are selected at intervals of 1 MVA.
And calculating equivalent power supply voltage time domain data corresponding to each preset short circuit capacity according to the method provided by the embodiment of the invention.
Fig. 5 is a graph illustrating an equivalent power supply voltage trend plotted by time domain data of an equivalent power supply voltage provided according to an embodiment of the present invention, wherein (a) in fig. 5 corresponds to a preset short-circuit capacity of 400MVA, (b) in fig. 5 corresponds to a preset short-circuit capacity of 600MVA, (c) in fig. 5 corresponds to a preset short-circuit capacity of 800MVA, and (d) in fig. 5 corresponds to a preset short-circuit capacity of 1000 MVA. Referring to fig. 5, as the short-circuit capacity increases, the effective value of the equivalent power supply voltage gradually becomes stable, but when the preset short-circuit capacity exceeds 800MVA, the fluctuation amount of the effective value of the equivalent power supply voltage significantly increases, which indicates that the actual value of the short-circuit capacity of the power system is around 800 MVA.
Fig. 6 shows a corresponding relationship between the short-circuit capacity and the equivalent power supply voltage variation coefficient in the embodiment of the invention. As can be seen from fig. 6, the short-circuit capacity of the power system in the embodiment of the present invention is 792 MVA.
Further, in order to reduce the error caused by the background unexpected interference to the calculation of the short-circuit capacity, 12 sets of electric power system short-circuit capacities corresponding to the voltage time domain data and the current time domain data are calculated respectively.
FIG. 7 shows a comparison of the results obtained by calculating the sets of voltage time domain data and current time domain data in the embodiment of the present invention. Wherein, fig. 7 (a) shows the corresponding relationship between the short-circuit capacity and the equivalent power supply voltage variation coefficient corresponding to each set of collected data, and fig. 7 (b) shows the short-circuit capacity corresponding to each set of collected data.
Referring to fig. 7, the short-circuit capacity corresponding to the minimum value of the equivalent power supply voltage variation coefficient calculated from each set of collected data is relatively close to be within 733-805 MVA.
Specifically, the short-circuit capacities calculated from the respective sets of collected data are 805MVA, 733MVA, 791MVA, 777MVA, 759MVA, 797MVA, 779MVA, 781MVA, 775MVA, 784MVA, MVA 743, and 766MVA, respectively. The maximum value and the minimum value in the 12 short-circuit capacities are deleted, and then the average value is calculated, so that the short-circuit capacity of 775.2MVA which is basically consistent with the given short-circuit capacity of 777.85MVA is finally obtained.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
Fig. 8 is a schematic structural diagram illustrating an apparatus for calculating a short-circuit capacity of an electrical power system according to an embodiment of the present invention. Referring to fig. 8, the power system short-circuit capacity calculation device 80 of the system according to the embodiment of the present invention may include: the system comprises a collected data acquisition module 810, a preset short circuit capacity acquisition module 820, an equivalent power supply voltage time domain data group calculation module 830, a variation coefficient calculation module 840 and a short circuit capacity determination module 850.
The collected data acquiring module 810 is configured to acquire collected data at a target power supply point of the power system, where the collected data includes a voltage time domain data set and a current time domain data set.
A preset short circuit capacity obtaining module 820, configured to obtain a preset short circuit capacity from a preset value range according to a preset obtaining rule, where the number of the preset short circuit capacity is greater than one.
And an equivalent power voltage time domain data group calculating module 830, configured to calculate, for each preset short circuit capacity, an equivalent power voltage time domain data group according to the preset short circuit capacity, the voltage time domain data group, and the current time domain data group.
And the variation coefficient calculating module 840 is used for calculating the variation coefficient of the voltage effective value data set aiming at each equivalent power supply voltage time domain data set.
The short-circuit capacity determining module 850 is configured to obtain a minimum variation coefficient, and use a preset short-circuit capacity corresponding to the minimum variation coefficient as the short-circuit capacity of the power system.
The short-circuit capacity calculation device for the power system, provided by the invention, can be suitable for the situation that the power system is not symmetrical, overcomes the sensitivity to three-phase unbalance, and improves the calculation accuracy of the short-circuit capacity.
In some embodiments, the equivalent power supply voltage time domain data set calculating module 830 is specifically configured to:
calculating the equivalent power supply voltage time domain data set according to an equivalent power supply voltage calculation formula;
the equivalent power supply voltage calculation formula includes:
wherein e (k) is equivalent power supply voltage time domain data of the target power supply point at a sampling point k, u (k) is voltage time domain data of the target power supply point at a sampling point k, i (k) is current time domain data of the target power supply point at a sampling point k, i (k +1) is current time domain data of the target power supply point at a sampling point k +1, and fSFor sampling frequency, RSIs a system equivalent resistance, XSIs the system equivalent reactance, f0At fundamental frequency, UNFor nominal voltage at target supply point, SSCThe short circuit capacity at the target power supply point.
In some embodiments, the coefficient of variation calculation module 840 is specifically configured to:
calculating a voltage effective value data set aiming at each equivalent power supply voltage time domain data set;
for each voltage valid value data set, a coefficient of variation is calculated.
Calculating the voltage effective value data set based on a voltage effective value calculation formula;
the voltage effective value calculation formula comprises:
wherein E (M) is the mth voltage effective value, M is the number of the middle voltage effective values in the voltage effective value data,
is as follows
Time domain data of equivalent power supply voltage of each sampling point fSIs the sampling frequency.
Calculating the coefficient of variation based on a coefficient of variation calculation formula;
the coefficient of variation calculation formula includes:
wherein, CVFor the coefficient of variation, e (m) is the voltage effective value data, σ (e (m)) is the standard deviation of the voltage effective value data, and μ (e (m)) is the expectation of the voltage effective value data.
In some embodiments, the collected data obtaining module 810 is specifically configured to:
and synchronously sampling to obtain a voltage time domain data group and a current time domain data group at the target power supply point of the power system.
In some embodiments, the power system short circuit capacity calculation device 80 further includes a mean value calculation module.
The average calculation module is specifically configured to: acquiring a preset number of acquired data, and respectively calculating the short circuit capacity corresponding to each acquired data to obtain the initial short circuit capacity of the preset number;
and calculating an average value of the initial short-circuit capacity, and taking the average value as the short-circuit capacity of the power system.
Fig. 9 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in fig. 9, the terminal device 90 of this embodiment includes: a processor 900, a memory 910, and a computer program 920, such as a power system short circuit capacity calculation program, stored in the memory 910 and operable on the processor 900. The processor 90, when executing the computer program 920, implements the steps in the above-mentioned embodiments of the power system short-circuit capacity calculation method, such as the steps S101 to S105 shown in fig. 1. Alternatively, the processor 900 executes the computer program 920 to implement the functions of the modules/units in the device embodiments, such as the functions of the modules 810 to 850 shown in fig. 8.
Illustratively, the computer program 920 may be partitioned into one or more modules/units that are stored in the memory 910 and executed by the processor 900 to implement the present invention. The 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 process of the computer program 920 in the terminal device 90. For example, the computer program 920 may be divided into an acquisition data module, a preset short-circuit capacity acquisition module, an equivalent power voltage time domain data group calculation module, a variation coefficient calculation module, and a short-circuit capacity determination module.
The terminal device 90 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 900, a memory 910. Those skilled in the art will appreciate that fig. 9 is merely an example of a terminal device 90 and does not constitute a limitation of the terminal device 90 and may include more or fewer components than shown, or some components may be combined, or different components, for example, the terminal device may also include input-output devices, network access devices, buses, etc.
The Processor 900 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 910 may be an internal storage unit of the terminal device 90, such as a hard disk or a memory of the terminal device 90. The memory 910 may also be an external storage device of the terminal device 90, 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, which are provided on the terminal device 90. Further, the memory 910 may also include both an internal storage unit and an external storage device of the terminal device 90. The memory 910 is used for storing the computer programs and other programs and data required by the terminal device. The memory 910 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
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; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A method for calculating short-circuit capacity of an electric power system is characterized by comprising the following steps:
acquiring collected data at a target power supply point of a power system, wherein the collected data comprises a voltage time domain data set and a current time domain data set;
acquiring preset short-circuit capacity from a preset value range according to a preset acquisition rule, wherein the number of the preset short-circuit capacity is more than one;
aiming at each preset short circuit capacity, calculating an equivalent power supply voltage time domain data set according to the preset short circuit capacity, the voltage time domain data set and the current time domain data set;
calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group;
and acquiring the coefficient of variation with the minimum value, and taking the preset short-circuit capacity corresponding to the coefficient of variation with the minimum value as the short-circuit capacity of the power system.
2. The method of claim 1, wherein the calculating an equivalent power supply voltage time domain data set from the preset short circuit capacity, the voltage time domain data set and the current time domain data set for each preset short circuit capacity comprises:
calculating the equivalent power supply voltage time domain data set according to an equivalent power supply voltage calculation formula;
the equivalent power supply voltage calculation formula includes:
wherein e (k) is equivalent power supply voltage time domain data of the target power supply point at a sampling point k, u (k) is voltage time domain data of the target power supply point at a sampling point k, i (k) is current time domain data of the target power supply point at a sampling point k, i (k +1) is current time domain data of the target power supply point at a sampling point k +1, and fSFor sampling frequency, RSIs a system equivalent resistance, XSIs the system equivalent reactance, f0At fundamental frequency, UNFor nominal voltage at target supply point, SSCThe short circuit capacity at the target power supply point.
3. The power system short circuit capacity calculation method of claim 1, wherein calculating, for each equivalent power supply voltage time domain data set, a coefficient of variation for the voltage effective value data set comprises:
calculating a voltage effective value data set aiming at each equivalent power supply voltage time domain data set;
for each voltage valid value data set, a coefficient of variation is calculated.
4. The power system short circuit capacity calculation method of claim 3, wherein said calculating a voltage effective value data set for each equivalent power supply voltage time domain data set comprises:
calculating the voltage effective value data set based on a voltage effective value calculation formula;
the voltage effective value calculation formula comprises:
wherein E (M) is the mth voltage effective value, M is the number of the middle voltage effective values in the voltage effective value data,
is as follows
Time domain data of equivalent power supply voltage of each sampling point fSIs the sampling frequency.
5. The power system short circuit capacity calculation method of claim 3, wherein the calculating a coefficient of variation for each voltage effective value data set comprises:
calculating the coefficient of variation based on a coefficient of variation calculation formula;
the coefficient of variation calculation formula includes:
wherein, CVFor the coefficient of variation, e (m) is the voltage effective value data, σ (e (m)) is the standard deviation of the voltage effective value data, and μ (e (m)) is the expectation of the voltage effective value data.
6. The power system short-circuit capacity calculation method according to any one of claims 1 to 5, wherein the acquiring of the collected data at the target power supply point of the power system comprises:
and synchronously sampling to obtain a voltage time domain data group and a current time domain data group at the target power supply point of the power system.
7. The method according to any one of claims 1 to 5, wherein after obtaining the minimum coefficient of variation and using the preset short-circuit capacity corresponding to the minimum coefficient of variation as the short-circuit capacity of the power system, the method further comprises:
acquiring a preset number of acquired data, and respectively calculating the short circuit capacity corresponding to each acquired data to obtain the initial short circuit capacity of the preset number;
and calculating an average value of the initial short-circuit capacity, and taking the average value as the short-circuit capacity of the power system.
8. An electric power system short circuit capacity calculation apparatus, comprising:
the acquisition module of the collected data is used for acquiring the collected data at the target power supply point of the power system, and the collected data comprises a voltage time domain data set and a current time domain data set;
the system comprises a preset short-circuit capacity acquisition module, a short-circuit capacity acquisition module and a short-circuit capacity acquisition module, wherein the preset short-circuit capacity acquisition module is used for acquiring preset short-circuit capacity from a preset value range according to a preset acquisition rule, and the number of the preset short-circuit capacity is more than one;
the equivalent power supply voltage time domain data group calculating module is used for calculating an equivalent power supply voltage time domain data group according to each preset short circuit capacity and the voltage time domain data group and the current time domain data group;
the variation coefficient calculation module is used for calculating the variation coefficient of the voltage effective value data group aiming at each equivalent power supply voltage time domain data group;
and the short-circuit capacity determining module is used for acquiring the variation coefficient with the minimum value and taking the preset short-circuit capacity corresponding to the variation coefficient with the minimum value as the short-circuit capacity of the power system.
9. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.
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