CN110879311A - Method for calculating power of power grid - Google Patents

Method for calculating power of power grid Download PDF

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CN110879311A
CN110879311A CN201911211129.6A CN201911211129A CN110879311A CN 110879311 A CN110879311 A CN 110879311A CN 201911211129 A CN201911211129 A CN 201911211129A CN 110879311 A CN110879311 A CN 110879311A
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power
voltage
value
current
formula
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晋阳珺
杜振华
赵靖
王志华
赵立刚
肖彬
王建东
艾志虎
程文雁
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Beijing Sifang Automation Co Ltd
Beijing Sifang Engineering Co Ltd
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Beijing Sifang Automation Co Ltd
Beijing Sifang Engineering Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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    • G01R21/06—Arrangements for measuring electric power or power factor by measuring current and voltage
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
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Abstract

The invention discloses a method for accurately calculating power of a power grid, which comprises the following steps: sampling data of the voltage and the current at the original voltage sampling point and the original current sampling point; converting the sampled data to obtain a real part and an imaginary part of a value of each frequency; obtaining a first parameter through the obtained real part and imaginary part; obtaining a second parameter related to a phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method of a power grid; and obtaining the power active value and the power passive value of the power grid. The method solves the problems that the calculation amount is large in the prior art, the operation load of a measurement and control device is caused by complex operations such as power factor angle calculation, sine real-time calculation, cosine real-time calculation and the like, substitution errors are generated in the calculation process, and the like. The power value calculated by the method completely meets the precision requirement specified by the power technical standard, and the power value can be quickly and accurately calculated in the process of numerical mutation.

Description

Method for calculating power of power grid
Technical Field
The invention belongs to the field of intelligent substations, and particularly relates to a method for calculating power of a power grid by a frequency domain method to improve calculation efficiency and realize real-time, rapid and accurate calculation of the power grid.
Background
At present, an intelligent substation needs to accurately obtain power value information in real time, can provide data basis for intelligent power dispatching, and also provides data support for real-time power grid monitoring. Therefore, the power of the power grid can be calculated quickly and accurately in real time, and the development of the smart power grid is promoted.
In the prior art, a frequency domain method is used for calculating power of a power grid, namely, fundamental wave and each subharmonic value are firstly decomposed aiming at voltage and current in the power grid, then power of the fundamental wave and each subharmonic is calculated in sequence, and then power values are obtained by accumulation; in other words, the frequency domain method obtains the active power and the reactive power by accumulating the power values of the fundamental wave and each subharmonic, wherein the active power and the reactive power of the fundamental wave and each subharmonic are calculated by using the effective values and the corresponding power angles of the voltage and the current at the fundamental wave and each subharmonic. The frequency domain method is shown in the following formula (1).
Figure BDA0002298143100000011
In the above formula (1), U represents a voltage effective value, I represents a current effective value,
Figure BDA0002298143100000012
and the power angle is represented, i represents the harmonic frequency based on the power frequency of the power grid, and n represents the highest harmonic frequency participating in power calculation.
However, in the process of calculating the power of the power grid, not only the voltage and the current need to be subjected to spectrum analysis, but also the power angle between the voltage and the current and the corresponding sine and cosine values need to be calculated, so that the following technical problems exist:
(1) the calculation amount in the real-time information calculation process is extremely large, so that the high load of a CPU is caused, and the occupancy rate of processing resources of the CPU is continuously high, so that the energy consumption is increased, and the heat dissipation problem is caused;
(2) errors are brought in the process of calculating power angles among the voltage and the current and corresponding sine and cosine values;
(3) the accuracy of data calculation at the moment of data mutation is reduced due to a large amount of calculation, and meanwhile, the performance requirement of monitoring the power grid data in real time is influenced.
In view of the foregoing, there is a need in the art for an improved frequency domain method, which can reduce the calculation amount and reduce the introduced error, so as to obtain the power frequency domain calculation value accurately in real time.
Disclosure of Invention
In order to solve the problems, the invention discloses a method for calculating the power of a power grid, which can reduce the calculated amount of a frequency domain method, simultaneously the calculated power value meets the principle of the frequency domain method, the load and the energy consumption of a CPU are reduced, the heat dissipation problem of the CPU is relieved, meanwhile, the introduction of errors in the calculation process is avoided, the efficiency and the precision of the measurement and control device for calculating the power value in real time are improved, the power value can be quickly and accurately calculated in the numerical mutation process, and the performance requirement of monitoring the power grid data in real time can be met.
The invention specifically adopts the following technical scheme.
A method of calculating grid power, comprising the steps of: step S1: for the selected power grid, sampling data of voltage and current at the original voltage sampling point and the original current sampling point at the same time point as the voltage; step S2: converting the sampled voltage and current data to obtain a real part and an imaginary part of a value of each frequency; step S3: obtaining a first parameter through the obtained real part and imaginary part; step S4: obtaining a second parameter related to a phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method of a power grid; step S5: and obtaining the power active value and the power passive value of the power grid.
According to an embodiment of the invention, the method further comprises: step S6: and outputting and displaying the obtained power active value and power passive value of the power grid.
According to one embodiment of the present invention, the transformation process performed on the sampled voltage and current data in step S2 is an inverse fourier transform. Or the transform processing performed on the sampled voltage and current data in step S2 is a fast fourier transform. The first parameter in step S3 includes a corresponding amplitude and phase angle. The second parameters in step S4 include sine and cosine values for the phase angle generated using the real and imaginary parts. The power angle parameter in step S4 includes a sine value and a cosine value of the power angle.
According to an embodiment of the present invention, in step S4, obtaining the second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure BDA0002298143100000021
the method for obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method comprises the following steps: and (3) decomposing sine and cosine values of the power angle by adopting an equation:
Figure BDA0002298143100000022
in step S5, the obtaining the active and inactive power values of the power grid further includes: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure BDA0002298143100000031
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure BDA0002298143100000032
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure BDA0002298143100000033
after the power value of the ith harmonic is obtained, the power values corresponding to the fundamental wave and the harmonic are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention.
Figure BDA0002298143100000034
Wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure BDA0002298143100000036
and the power angle is represented, i represents the harmonic frequency based on the power frequency of the power grid, and n represents the highest harmonic frequency participating in power calculation.
Figure BDA0002298143100000035
Wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiRepresenting the imaginary part of the ith harmonic current.
The invention also requests to protect the application of the method for calculating the power of the power grid in the intelligent substation or the embedded secondary device, wherein the method for calculating the power of the power grid is the method for calculating the power of the power grid.
The invention also requests to protect a system of the intelligent substation, which is used for calculating the power of the power grid, wherein the system comprises a sampling module, a transformation module, a processing module, a storage module and a display module. Wherein the sampling module is configured to: for the selected power grid, sampling data of voltage and current at the original voltage sampling point and the original current sampling point at the same time point as the voltage; the transformation module is configured to: converting the sampled voltage and current data to obtain a real part and an imaginary part of a value of each frequency; the processing module is configured to: obtaining a first parameter through the obtained real part and imaginary part; obtaining a second parameter related to the phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method; obtaining a power active value and a power passive value of a power grid; wherein the processing module is further configured to: converting the voltage and current sampling data to obtain a real part and an imaginary part of a value of each frequency; calculating corresponding amplitude and phase angle according to the real part and imaginary part of the obtained value of each frequency; obtaining a second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure BDA0002298143100000041
the method for obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method comprises the following steps: and (3) decomposing sine and cosine values of the power angle by adopting an equation:
Figure BDA0002298143100000042
obtaining the active and inactive values of power of the power grid further comprises: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure BDA0002298143100000043
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure BDA0002298143100000044
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure BDA0002298143100000045
after the power value of the ith harmonic wave is obtained, the power values corresponding to the fundamental wave and the harmonic wave are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention;
Figure BDA0002298143100000051
wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure BDA0002298143100000055
representing a power angle, i representing the harmonic frequency based on the power frequency of the power grid, and n representing the highest harmonic frequency participating in power calculation;
Figure BDA0002298143100000052
wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiRepresenting the imaginary part of the ith harmonic current.
The storage module is configured to store voltage and current sampling data, a real part and an imaginary part of a value of each frequency, a first parameter obtained by obtaining the real part and the imaginary part, a second parameter related to a phase angle obtained based on the first parameter, a power angle parameter of the real part and the imaginary part obtained according to a power frequency domain method, and a power active value and a power passive value of a power grid; and the display module is configured to: and outputting and displaying the obtained power active value and power passive value of the power grid.
The invention also requests to protect a system in the embedded secondary device, which is used for calculating the power of the power grid, wherein the system comprises a sampling module, a conversion module, a processing module, a storage module and a display module. Wherein the sampling module is configured to: for the selected power grid, sampling data of voltage and current at the original voltage sampling point and the original current sampling point at the same time point as the voltage; the transformation module is configured to: converting the sampled voltage and current data to obtain a real part and an imaginary part of a value of each frequency; the processing module is configured to: obtaining a first parameter through the obtained real part and imaginary part; obtaining a second parameter related to the phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method; obtaining a power active value and a power passive value of a power grid; wherein the processing module is further configured to: converting the voltage and current sampling data to obtain a real part and an imaginary part of a value of each frequency; calculating corresponding amplitude and phase angle according to the real part and imaginary part of the obtained value of each frequency; obtaining a second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure BDA0002298143100000053
the method for obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method comprises the following steps: and (3) decomposing sine and cosine values of the power angle by adopting an equation:
Figure BDA0002298143100000054
obtaining the active and inactive values of power of the power grid further comprises: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure BDA0002298143100000061
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure BDA0002298143100000062
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure BDA0002298143100000063
after the power value of the ith harmonic wave is obtained, the power values corresponding to the fundamental wave and the harmonic wave are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention;
Figure BDA0002298143100000064
wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure BDA0002298143100000066
representing a power angle, i representing the harmonic frequency based on the power frequency of the power grid, and n representing the highest harmonic frequency participating in power calculation;
Figure BDA0002298143100000065
wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiRepresenting the imaginary part of the ith harmonic current.
The storage module is configured to store voltage and current sampling data, a real part and an imaginary part of a value of each frequency, a first parameter obtained by obtaining the real part and the imaginary part, a second parameter related to a phase angle obtained based on the first parameter, a power angle parameter of the real part and the imaginary part obtained according to a power frequency domain method, and a power active value and a power passive value of a power grid; and the display module is configured to: and outputting and displaying the obtained power active value and power passive value of the power grid.
The invention simplifies the process of power calculation by using the relation between the real part and the imaginary part of the voltage and the current and the phase angle, improves the high efficiency of the calculation data, and can calculate the power value in real time, quickly and accurately.
Drawings
Fig. 1 is a method for calculating grid power according to one embodiment of the invention.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to the accompanying drawings.
Fig. 1 is a method for calculating grid power according to one embodiment of the invention. The method comprises the following steps:
step S1: for the selected power grid, sampling data of voltage and current at the original voltage sampling point and the original current sampling point at the same time point as the voltage;
step S2: converting the sampled voltage and current data to obtain a real part and an imaginary part of a value of each frequency;
step S3: obtaining a first parameter through the obtained real part and imaginary part;
step S4: obtaining a second parameter related to the phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method;
step S5: and obtaining the power active value and the power passive value of the power grid.
Preferably, the method further comprises step S6: and outputting and displaying the obtained power active value and power passive value of the power grid.
Preferably, the transform processing performed on the sampled voltage and current data in step S2 is an inverse fourier transform.
Preferably, the transform processing performed on the sampled voltage and current data in step S2 is a fast fourier transform.
Preferably, in step S2, the voltage and current sample data are subjected to inverse fourier transform to obtain effective values of the voltage and current at the fundamental wave and each harmonic.
Alternatively, in step S2, the real part and the imaginary part of the value of each frequency are obtained by performing Fast Fourier Transform (FFT) on the voltage and current sample data.
Preferably, the first parameter in step S3 includes a corresponding magnitude and phase angle.
Preferably, in step S3, the corresponding magnitude and phase angle are calculated by the real part and imaginary part of the obtained value of each frequency.
Preferably, the second parameters in step S4 include sine and cosine values for the phase angle generated using the real and imaginary parts.
Preferably, the power angle parameter in step S4 includes a sine value and a cosine value of the power angle.
Preferably, in step S4, obtaining the second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure BDA0002298143100000071
preferably, in step S4, the obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method includes: and (3) decomposing sine and cosine values of the power angle by adopting an equation:
Figure BDA0002298143100000085
preferably, in step S5, the obtaining the active power value and the inactive power value of the power grid further includes: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure BDA0002298143100000086
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure BDA0002298143100000081
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure BDA0002298143100000082
after the power value of the ith harmonic is obtained, the power values corresponding to the fundamental wave and the harmonic are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention.
Figure BDA0002298143100000083
Wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure BDA0002298143100000087
and the power angle is represented, i represents the harmonic frequency based on the power frequency of the power grid, and n represents the highest harmonic frequency participating in power calculation.
Figure BDA0002298143100000084
Wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiRepresenting the imaginary part of the ith harmonic current.
The method for calculating the power value can obviously reduce the operation amount, reduce the load and the energy consumption of the CPU and relieve the heat dissipation problem of the CPU, simultaneously avoid the introduction of errors in the calculation process, improve the efficiency and the precision of the measurement and control device for calculating the power value in real time, quickly and accurately calculate the power value in the process of numerical mutation, and meet the performance requirement of monitoring the power grid data in real time.
Preferably, the method for calculating the power of the power grid is applied to an intelligent substation measurement and control device.
In conclusion, the invention simplifies the process of power calculation, improves the efficiency of data calculation and can calculate the power value in real time, quickly and accurately by utilizing the relation between the real part and the imaginary part of the voltage and the current and the phase angle.
According to an embodiment of the invention, the invention further discloses application of the method for calculating the power of the power grid in an intelligent substation or an embedded secondary device, wherein the method for calculating the power of the power grid is the method for calculating the power of the power grid.
According to an embodiment of the invention, the invention further discloses a system for calculating the power of the power grid, which comprises a sampling module, a conversion module, a processing module, a storage module and a display module.
Wherein the sampling module is configured to: and for the selected power grid, sampling data of the voltage and the current at the original voltage sampling point and the original current sampling point at the same time point as the voltage.
The transformation module is configured to: and converting the sampled voltage and current data to obtain a real part and an imaginary part of the value of each frequency.
The processing module is configured to: obtaining a first parameter through the obtained real part and imaginary part; obtaining a second parameter related to the phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method; and obtaining the power active value and the power passive value of the power grid.
Wherein the processing module is further configured to: converting the voltage and current sampling data to obtain a real part and an imaginary part of a value of each frequency; calculating corresponding amplitude and phase angle according to the real part and imaginary part of the obtained value of each frequency; obtaining a second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure BDA0002298143100000091
the method for obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method comprises the following steps: and (3) decomposing sine and cosine values of the power angle by adopting an equation:
Figure BDA0002298143100000092
obtaining the active and inactive values of power of the power grid further comprises: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure BDA0002298143100000101
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure BDA0002298143100000102
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure BDA0002298143100000103
after the power value of the ith harmonic wave is obtained, the power values corresponding to the fundamental wave and the harmonic wave are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention;
Figure BDA0002298143100000104
wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure BDA0002298143100000106
and the power angle is represented, i represents the harmonic frequency based on the power frequency of the power grid, and n represents the highest harmonic frequency participating in power calculation.
Figure BDA0002298143100000105
Wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiRepresenting the imaginary part of the ith harmonic current.
The storage module is configured to store voltage and current sampling data, a real part and an imaginary part of a value of each frequency, a first parameter obtained by obtaining the real part and the imaginary part, a second parameter related to a phase angle obtained based on the first parameter, a power angle parameter of the real part and the imaginary part obtained according to a power frequency domain method, and a power active value and a power passive value of a power grid.
The display module is configured to: and outputting and displaying the obtained power active value and power passive value of the power grid.
Preferably, the system is provided in a smart substation or an embedded secondary device for calculating grid power.
The system of the invention is used for calculating the power value, can obviously reduce the operation amount, reduce the load and the energy consumption of the CPU and relieve the heat dissipation problem of the CPU, simultaneously avoids the introduction of errors in the calculation process, improves the efficiency and the precision of the measurement and control device for calculating the power value in real time, can also quickly and accurately calculate the power value in the process of numerical mutation, and can also meet the performance requirement of monitoring the power grid data in real time.
It should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

Claims (10)

1. A method of calculating grid power, comprising the steps of:
step S1: for the selected power grid, sampling data of voltage and current at the original voltage sampling point and the original current sampling point at the same time point as the voltage;
step S2: converting the sampled voltage and current data to obtain a real part and an imaginary part of a value of each frequency;
step S3: obtaining a first parameter through the obtained real part and imaginary part;
step S4: obtaining a second parameter related to a phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method of a power grid;
step S5: and obtaining the power active value and the power passive value of the power grid.
2. The method of calculating grid power as claimed in claim 1, wherein the method further comprises:
step S6: and outputting and displaying the obtained power active value and power passive value of the power grid.
3. The method of calculating grid power as claimed in claim 2, wherein:
the transform processing performed on the sampled voltage and current data in step S2 is an inverse fourier transform.
4. The method of calculating grid power as claimed in claim 2, wherein:
the transform processing performed on the sampled voltage and current data in step S2 is a fast fourier transform.
5. The method of calculating grid power as claimed in claim 3 or 4, wherein:
the first parameter in step S3 includes a corresponding amplitude and phase angle.
6. The method of calculating grid power of claim 5, wherein:
the second parameters in step S4 include sine and cosine values for the phase angle generated using the real and imaginary parts.
7. The method of calculating grid power as claimed in claim 6, wherein:
the power angle parameter in step S4 includes a sine value and a cosine value of the power angle.
8. The method of calculating grid power as claimed in claim 7, wherein:
in step S4, obtaining the second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure FDA0002298143090000021
the method for obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method comprises the following steps: adopts the formula (3) to the power angle
Figure FDA0002298143090000029
Decomposing sine and cosine values of the four-dimensional space:
Figure FDA0002298143090000022
in step S5, the obtaining the active and inactive power values of the power grid further includes: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure FDA0002298143090000023
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure FDA0002298143090000024
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure FDA0002298143090000025
after the power value of the ith harmonic is obtained, the power values corresponding to the fundamental wave and the harmonic are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention.
Figure FDA0002298143090000026
Wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure FDA0002298143090000028
and the power angle is represented, i represents the harmonic frequency based on the power frequency of the power grid, and n represents the highest harmonic frequency participating in power calculation.
Figure FDA0002298143090000027
Wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiRepresenting the imaginary part of the ith harmonic current.
9. Use of a method of calculating grid power in a smart substation, wherein the method of calculating grid power is the method of calculating grid power according to claim 8.
10. A system in an intelligent substation is used for calculating power of a power grid, and comprises a sampling module, a transformation module, a processing module, a storage module and a display module;
wherein the sampling module is configured to: for the selected power grid, sampling data of voltage and current at the original voltage sampling point and the original current sampling point at the same time point as the voltage;
the transformation module is configured to: converting the sampled voltage and current data to obtain a real part and an imaginary part of a value of each frequency;
the processing module is configured to: obtaining a first parameter through the obtained real part and imaginary part; obtaining a second parameter related to the phase angle based on the first parameter, and obtaining power angle parameters of a real part and an imaginary part according to a power frequency domain method; obtaining a power active value and a power passive value of a power grid;
wherein the processing module is further configured to: converting the voltage and current sampling data to obtain a real part and an imaginary part of a value of each frequency; calculating corresponding amplitude and phase angle according to the real part and imaginary part of the obtained value of each frequency; obtaining a second parameter related to the phase angle includes: for a voltage or current of a certain frequency, the following relation between the real part and the imaginary part of the voltage or current and the phase angle theta of the voltage or current is obtained, and the relation is shown in an equation (2):
Figure FDA0002298143090000031
the method for obtaining the power angle parameters of the real part and the imaginary part according to the power frequency domain method comprises the following steps: and (3) decomposing sine and cosine values of the power angle by adopting an equation:
Figure FDA0002298143090000032
obtaining the active and inactive values of power of the power grid further comprises: the formula (2) is taken into the formula (3), and sine and cosine values of the power angle expressed by a real part and an imaginary part are obtained, as shown in the formula (4):
Figure FDA0002298143090000033
for the effective values of the voltage and the current, the real part and the imaginary part are used for representation, and the formula (5) shows that:
Figure FDA0002298143090000041
combining the formula (4) and the formula (5), obtaining a power value corresponding to the ith harmonic by using a calculation formula obtained by using a real part and an imaginary part of voltage and current, as shown in the formula (6):
Figure FDA0002298143090000042
after the power value of the ith harmonic wave is obtained, the power values corresponding to the fundamental wave and the harmonic wave are accumulated to obtain a power frequency domain value, namely, the formula (6) is carried into the formula (7), and then the formula (8) is obtained to obtain the active power and the reactive power of the power grid, namely, the improved frequency domain method for calculating the power of the power grid is provided by the invention;
Figure FDA0002298143090000043
wherein U isiRepresenting the effective value of the voltage, IiWhich represents the effective value of the current,
Figure FDA0002298143090000045
representing a power angle, i representing the harmonic frequency based on the power frequency of the power grid, and n representing the highest harmonic frequency participating in power calculation;
Figure FDA0002298143090000044
wherein R isuiRepresenting the real part of the ith harmonic voltage, IuiRepresenting the imaginary part, R, of the ith harmonic voltageiiRepresenting the real part of the ith harmonic current, IiiAn imaginary part representing the ith harmonic current;
the storage module is configured to store voltage and current sampling data, a real part and an imaginary part of a value of each frequency, a first parameter obtained by obtaining the real part and the imaginary part, a second parameter related to a phase angle obtained based on the first parameter, a power angle parameter of the real part and the imaginary part obtained according to a power frequency domain method, and a power active value and a power passive value of a power grid; and
the display module is configured to: and outputting and displaying the obtained power active value and power passive value of the power grid.
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