CN109298234B - Reactive power detection device and method - Google Patents
Reactive power detection device and method Download PDFInfo
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- CN109298234B CN109298234B CN201710612474.5A CN201710612474A CN109298234B CN 109298234 B CN109298234 B CN 109298234B CN 201710612474 A CN201710612474 A CN 201710612474A CN 109298234 B CN109298234 B CN 109298234B
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- G01R21/001—Measuring real or reactive component; Measuring apparent energy
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Abstract
The embodiment of the invention discloses a reactive power detection device and a method. The method comprises the following steps: acquiring current voltage and current of a target point to be measured in a circuit to be measured in each subsystem of a wind power generation system; determining a first component and a second component of the current voltage and the current respectively, wherein the second component is a component which is 90 degrees different from the phase corresponding to the first component; and calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and current. The reactive power detection device and method provided by the embodiment of the invention can reduce the calculated amount and error of reactive power detection and improve the real-time performance of reactive power detection.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a reactive power detection device and method.
Background
In the grid, there are two types of electrical power supplied by the power source to the load: one is active power and the other is reactive power. Active power is the electric power required to keep the electrical equipment operating normally, i.e. the electric power that converts electrical energy into other forms of energy (mechanical, optical, thermal). Reactive power is electrical power used for electric and magnetic fields within an electrical circuit and to establish and maintain magnetic fields in electrical equipment.
Improper reactive power can cause problems of increased equipment capacity, increased equipment and line losses, overheating and excessive line transmission voltage drop during operation of the power system. These problems will directly affect the transmission efficiency of electric energy, and unnecessary economic loss is increased in the transmission link. Therefore, it is necessary to detect the reactive power quickly and accurately.
Currently, there are two main methods for detecting reactive power: fourier measurements and digital phase-shift measurements. The Fourier measurement method is that voltage signals and current signals on a measured loop are uniformly sampled according to a whole period, then a group of orthogonal trigonometric functions (sine quantity or cosine quantity) are used for carrying out orthogonal decomposition on sampling values according to Fourier series, and reactive power of a line is calculated by using each decomposition value. The digital phase-shift measurement method is to uniformly sample voltage and current in a full period, and then to multiply the voltage sampling value by the current sampling value lagging 90 degrees (1/4 periods) to perform integral calculation, thereby obtaining the average reactive power in the full period.
However, the fourier measurement method is used to detect the reactive power, and the calculation amount is large. The reactive power is detected by using a digital phase-shifting measurement method, the real-time performance is poor, and if multiple harmonics exist in the measured value, the detected reactive power has a large error.
Disclosure of Invention
The embodiment of the invention provides a reactive power detection device and method, which can reduce the calculated amount and error of reactive power detection and improve the real-time performance of the reactive power detection.
In one aspect, an embodiment of the present invention provides a reactive power detection apparatus, where the apparatus includes: a voltage acquisition module, a current acquisition module, a phase shift module and a calculation module, wherein,
the voltage acquisition module and the current acquisition module are used for respectively and correspondingly acquiring the current voltage and the current of a target point to be measured in a circuit to be measured in each subsystem in the wind power generation system;
the phase shifting module is used for determining a first component and a second component of the current voltage and/or current respectively, wherein the second component is a component which has a phase difference of 90 degrees and corresponds to the first component; the number of the phase shift modules is one when the phase shift modules are used for determining the first component and the second component of the current voltage and the current respectively, and the number of the phase shift modules is two when the phase shift modules are used for determining the first component and the second component of the current voltage or the current respectively;
and the calculation module is used for calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and current.
On the other hand, an embodiment of the present invention provides a reactive power detection method, including:
acquiring current voltage and current of a target point to be measured in a circuit to be measured in each subsystem of a wind power generation system;
determining a first component and a second component of the current voltage and the current respectively, wherein the second component is a component which is 90 degrees different from the phase corresponding to the first component;
and calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and current.
Compared with the Fourier measurement method in the prior art, the reactive power detection device and method provided by the embodiment of the invention have the advantages that the calculated amount is small; compared with the digital phase-shifting measurement method in the prior art, the voltage and the current of the embodiment of the invention are both the current voltage and the current, the calculated reactive power is the current reactive power instead of the average reactive power, and the real-time performance is stronger; in addition, the reactive power detection method provided by the embodiment of the invention is less affected by harmonic waves, so that the detected reactive power error is smaller.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart illustrating a reactive power detection method according to an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating a first structure of a reactive power detection apparatus provided in an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a second structure of a reactive power detection apparatus provided in an embodiment of the present invention;
fig. 4 shows a third schematic structural diagram of a reactive power detection device provided in the embodiment of the present invention.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
As shown in fig. 1, fig. 1 is a schematic flowchart illustrating a reactive power detection method provided by an embodiment of the present invention. It may include:
s101: the method comprises the steps of collecting the current voltage and the current of a target point to be measured in a circuit to be measured in each subsystem of the wind power generation system.
S102: a first component and a second component of the present voltage and the present current, respectively, are determined.
Wherein the second component is a component having a phase different by 90 ° from the phase corresponding to the first component.
S103: and calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and current.
The wind power generation system comprises a wind power generation subsystem, a wind power generation control subsystem, a wind power generation protection subsystem, an electric variable pitch control subsystem and the like.
The circuit under test described above may be a single phase circuit.
In one embodiment of the present invention, determining the respective first and second components of the present voltage and the present current may comprise: calculating a first difference value of the current voltage and the first component of the voltage collected last time, and a second difference value of the current and the first component of the current collected last time; calculating a third difference between the first difference and the last acquired second component of the voltage, and a fourth difference between the second difference and the last acquired second component of the current; calculating a first product value of the third difference value and the frequency of the circuit to be tested, and a second product value of the fourth difference value and the frequency of the circuit to be tested; performing integral calculation on the first product value to obtain a first integral value, and performing integral calculation on the second product value to obtain a second integral value, wherein the first integral value is used as a first component of the current voltage, and the second integral value is used as a first component of the current; performing integral calculation on the first integral value to obtain a third integral value, and performing integral calculation on the second integral value to obtain a fourth integral value; and calculating a third product value of the third integral value and the frequency, and calculating a fourth product value of the fourth integral and the frequency, wherein the third product value is used as a second component corresponding to the current voltage, and the fourth product value is used as a second component corresponding to the current.
For example, the following description will be made by taking a voltage as an example.
Suppose the current voltage collected is u (t), and the last voltage collected is u0(t) the first component of the last acquired voltage is uα0(t) the second component of the last acquired voltage is uβ0(t)。
The difference between the current voltage and the first component of the last acquired voltage is u (t) -uα0(t)。
The difference between the first component of the present voltage and the last acquired voltage and the second component u of the last acquired voltageβ0The difference of (t) is u (t) -uα0(t)-uβ0(t)。
Let the frequency of the circuit under test be ω.
The first component u of the present voltage and the last acquired voltageα0(t) the difference with the second component u of the last acquired voltageβ0The product of the difference value of (t) and the frequency omega of the circuit to be tested is omega (u (t) -uα0(t)-uβ0(t))。
Calculation of ω (u (t) -u by Laplace transformα0(t)-uβ0(t)) and taking the calculated integrated value as the first component of the current voltage.
Among them, the laplace transform is an integral transform commonly used in engineering mathematics, also known as the laplace transform. The laplace transform is a linear transform that transforms a function with a parameter real number t into a function with a parameter complex number s.
The first component of the current voltage u (t) is represented as follows:
wherein, Uα(s) is a first component of the current voltage u (t) expressed by a parameter of a complex number s, ω is the frequency of the circuit to be tested, s is a laplace transform operator, and u(s) is the current voltage corresponding to the current voltage u (t) expressed by a parameter of a complex number s.
Computing U by Laplace transformαAnd(s), calculating the product of the integral value obtained by integral calculation and the frequency omega of the circuit to be measured, and taking the product value obtained by calculation as the second component of the current voltage.
The second component of the current voltage u (t) is represented as follows:
wherein, Uβ(s) is a second component of the current voltage u (t) expressed by a parameter of a complex number s, ω is the frequency of the circuit to be tested, s is a laplace transform operator, and u(s) is the current voltage corresponding to the current voltage u (t) expressed by a parameter of a complex number s.
In the vicinity of s ═ j ω, where j is the phase shift operator, there are
Uβ(s)＝s*Uα(s) (3)
Namely Uβ(s) to Uα(s) lags by 90. Namely, two signals with the same amplitude and the same frequency but different phases by 90 DEG can be obtained by the above processOutput Uα(s) and Uβ(s) the effect of shifting the phase by 90 degrees is achieved.
The process of calculating the first component and the second component of the present current is the same as the process of calculating the first component and the second component of the present voltage, which is not described herein again in the embodiments of the present invention, and reference may be specifically made to the process of calculating the first component and the second component of the present voltage.
The first component of the present current i (t) is represented as follows:
the second component of the present current i (t) is represented as follows:
wherein, Iα(s) is a first component of the present current I (t) expressed as a parameter with a complex number s, Iβ(s is a second component of the current i (t) represented by a complex number s as a parameter, ω is the frequency of the circuit to be measured, s is a laplace transform operator, and i(s) is the current represented by the complex number s as a parameter corresponding to the current i (t).
In an embodiment of the present invention, before calculating a third difference between the first difference and the second component of the voltage collected last time, and a fourth difference between the second difference and the second component of the current collected last time, the method may further include: and multiplying the first difference and/or the second difference by a preset value to obtain the adjusted first difference and/or second difference.
For example, the following description will be made by taking a voltage as an example.
Suppose the current voltage collected is u (t), and the last voltage collected is u0(t) the first component of the last acquired voltage is uα0(t) the second component of the last acquired voltage is uβ0(t)。
The current voltage is the first of the last acquired voltageA component difference of u (t) -uα0(t)。
The difference is adjusted by an adjustment factor k, i.e. u (t) -uα0(t) multiplying the difference by a predetermined value k, the adjusted difference being k (u (t) -uα0(t)). In one embodiment of the present invention, k may be greater than 0 and not greater than 1.
The adjusted difference value and the second component u of the last acquired voltageβ0The difference of (t) is k (u (t) -uα0(t))-uβ0(t)。
Let the frequency of the circuit under test be ω.
K (u (t) -uα0(t))-uβ0The product of (t) and the frequency ω of the circuit under test is ω (k (u (t) -u)α0(t))-uβ0(t))。
Calculation of ω (k (u (t) -u) by Laplace transformα0(t))-uβ0(t)) and taking the calculated integrated value as the first component of the current voltage.
The first component of the current voltage u (t) is represented as follows:
wherein, Uα(s) is a first component of the current voltage u (t) which is represented by a parameter which is a complex number s, ω is the frequency of the circuit to be tested, s is a Laplace transform operator, U(s) is the current voltage corresponding to the current voltage u (t) which is represented by the parameter which is the complex number s, k is an adjustment coefficient, and k is greater than 0 and not greater than 1.
Computing U by Laplace transformαAnd(s), calculating the product of the integral value obtained by integral calculation and the frequency omega of the circuit to be measured, and taking the product value obtained by calculation as the second component of the current voltage.
The second component of the current voltage u (t) is represented as follows:
wherein, Uβ(s) is a second component of the current voltage u (t) and expressed by a parameter of a complex number s, ω is the frequency of the circuit to be measured, s is a laplace transform operator, u(s) is the current voltage corresponding to the current voltage u (t) and expressed by a parameter of a complex number s, and k is an adjustment coefficient.
In the vicinity of s ═ j ω, where j is the phase shift operator, there are
Uβ(s)＝s*Uα(s) (8)
Namely Uβ(s) to Uα(s) lags by 90. Namely, two output quantities U with the same amplitude and the same frequency but different phases by 90 degrees can be obtained through the processα(s) and Uβ(s) the effect of shifting the phase by 90 degrees is achieved.
The first difference is adjusted by the adjustment coefficient, so that the calculation result can be more accurate.
The process of calculating the first component and the second component of the present current is the same as the process of calculating the first component and the second component of the present voltage, which is not described herein again in the embodiments of the present invention, and reference may be specifically made to the process of calculating the first component and the second component of the present voltage.
The first component of the present current i (t) is represented as follows:
the second component of the present current i (t) is represented as follows:
wherein, Iα(s) is a first component of the present current I (t) expressed as a parameter with a complex number s, Iβ(s is a second component of the current i (t) and expressed by a parameter of a complex number s, ω is the frequency of the circuit to be measured, s is a laplace transform operator, i(s) is the current corresponding to the current i (t) and expressed by a parameter of a complex number s, and k is an adjustment coefficient.
In an embodiment of the present invention, calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and current may include: and calculating the difference value of the product of the second component of the current voltage and the first component of the current and the product of the first component of the current voltage and the second component of the current, and taking the calculated difference value as the current reactive power of the target point to be measured.
q＝Uβ(s)*Iα(s)-Uα(s)*Iβ(s) (11)
Wherein q is the current reactive power of the target point to be measured, Uα(s)、Uβ(s)、Iα(s) and Iβ(s) a first component and a second component, respectively, of the present voltage u (t) and the present current i (t).
Compared with the Fourier measurement method in the prior art, the reactive power detection method has the advantages that the calculated amount is small; compared with the digital phase-shifting measurement method in the prior art, the voltage and the current of the embodiment of the invention are both the current voltage and the current, the calculated reactive power is the current reactive power instead of the average reactive power, and the real-time performance is stronger; in addition, the reactive power detection method provided by the embodiment of the invention is less affected by harmonic waves, so that the detected reactive power error is smaller.
Corresponding to the above method embodiment, the embodiment of the present invention further provides a reactive power detection apparatus.
As shown in fig. 2, fig. 2 is a schematic diagram illustrating a first structure of a reactive power detection apparatus according to an embodiment of the present invention. It may include: a voltage acquisition module 201, a current acquisition module 202, a phase shift module 203, and a calculation module 204, wherein,
the voltage acquisition module 201 is configured to acquire a current voltage of a target point to be measured in a circuit to be measured in each subsystem of the wind power generation system.
The current collection module 202 is configured to collect, for a target point to be measured in a circuit to be measured in each subsystem in the wind power generation system, a current voltage of the target point to be measured.
And a phase shift module 203 for determining a first component and a second component of the present voltage and the present current, respectively, wherein the second component is a component having a phase different from the phase of the first component by 90 °.
It should be noted that, when the method is used for determining the respective first component and second component of the present voltage and present current, the number of the phase shift modules is one; the number of phase-shifting modules is two when used for determining the respective first and second component of the present voltage or present current.
And the calculating module 203 is used for calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and current.
The wind power generation system comprises a wind power generation subsystem, a wind power generation control subsystem, a wind power generation protection subsystem, an electric variable pitch control subsystem and the like.
In an embodiment of the present invention, the phase shift module 202 of the embodiment of the present invention may include: the phase shift module comprises a first component difference value operator module, a second component difference value operator module, a first product calculation sub-module, a first integral calculation sub-module, a second integral calculation sub-module and a second product calculation sub-module (not shown in the figure); wherein the content of the first and second substances,
and the first component difference value operator module is used for calculating a first difference value of the current voltage and the first component of the voltage collected last time and/or calculating a second difference value of the current and the first component of the current collected last time.
And the second component difference value operator module is used for calculating a third difference value between the first difference value and the last collected second component of the voltage and/or calculating a fourth difference value between the second difference value and the last collected second component of the current.
And the first product calculation submodule is used for calculating a first product value of the third difference value and the frequency of the circuit to be tested, and/or calculating a second product value of the fourth difference value and the frequency of the circuit to be tested.
And the first integral calculation submodule is used for carrying out integral calculation on the first product value to obtain a first integral value and/or carrying out integral calculation on the second product value to obtain a second integral value, wherein the first integral value is used as a first component of the current voltage, and the second integral value is used as a first component of the current.
And the second integral calculation submodule is used for carrying out integral calculation on the first integral value to obtain a third integral value and/or carrying out integral calculation on the second integral value to obtain a fourth integral value.
And the second product calculation submodule is used for calculating a third product value of the third integral value and the frequency and/or calculating a fourth product value of a fourth integral and the frequency, wherein the third product value is used as a second component corresponding to the current voltage, and the fourth product value is used as a second component corresponding to the current.
For example, the following description will be made by taking a voltage as an example.
Assuming that the current voltage collected by the voltage collection module 201 is u (t); the last acquired voltage is u0(t) the first component of the last acquired voltage is uα0(t) the second component of the last acquired voltage is uβ0(t)。
The first component difference value operator module calculates the difference value of the current voltage and the first component of the last collected voltage as u (t) -uα0(t)。
The second component difference value operator module calculates the difference value of the current voltage and the first component of the last collected voltage and the second component u of the last collected voltageβ0The difference of (t) is u (t) -uα0(t)-uβ0(t)。
Let the frequency of the circuit under test be ω.
The first product computation submodule computes u (t) -uα0(t)-uβ0The product of (t) and the frequency ω of the circuit under test is ω (u (t) -uα0(t)-uβ0(t))。
The first integral computation submodule computes ω (u (t) -u by laplace transformα0(t)-uβ0(t)) and taking the calculated integrated value as the first component of the current voltage.
The first component of the current voltage u (t) is represented as follows:
wherein, Uα(s) is a first component of the current voltage u (t) expressed by a parameter of a complex number s, ω is the frequency of the circuit to be tested, s is a laplace transform operator, and u(s) is the current voltage corresponding to the current voltage u (t) expressed by a parameter of a complex number s.
The second integral calculation submodule calculates U through Laplace transformα(s) integration.
And the second product calculation submodule calculates the product of the integral value obtained by integral calculation of the second integral calculation submodule and the frequency omega of the circuit to be measured, and the calculated product value is used as a second component of the current voltage.
The second component of the current voltage u (t) is represented as follows:
wherein, Uβ(s) is a second component of the current voltage u (t) expressed by a parameter of a complex number s, ω is the frequency of the circuit to be tested, s is a laplace transform operator, and u(s) is the current voltage corresponding to the current voltage u (t) expressed by a parameter of a complex number s.
In the vicinity of s ═ j ω, where j is the phase shift operator, there are
Uβ(s)＝s*Uα(s) (14)
Namely Uβ(s) to Uα(s) lags by 90. Namely, two output quantities U with the same amplitude and the same frequency but different phases by 90 degrees can be obtained through the processα(s) and Uβ(s) the effect of shifting the phase by 90 degrees is achieved.
The process of calculating the first component and the second component of the present current is the same as the process of calculating the first component and the second component of the present voltage, which is not described herein again in the embodiments of the present invention, and reference may be specifically made to the process of calculating the first component and the second component of the present voltage.
The first component of the present current i (t) is represented as follows:
the second component of the present current i (t) is represented as follows:
wherein, Iα(s) is a first component of the present current I (t) expressed as a parameter with a complex number s, Iβ(s) is a second component of the current i (t) expressed by a parameter of a complex number s, ω is the frequency of the circuit to be tested, s is a laplace transform operator, and i(s) is the current represented by the parameter of the complex number s corresponding to the current i (t).
In an embodiment of the present invention, the phase shift module 203 of the embodiment of the present invention may further include: and the adjusting submodule is used for multiplying the first difference value and/or the second difference value by a preset value to obtain the adjusted first difference value and/or second difference value and outputting the adjusted first difference value and/or second difference value to the second component difference value operator module.
For example, the following description will be made by taking a voltage as an example.
Assume that the current voltage collected by the voltage collection module 201 is u (t), and the last voltage collected is u (t)0(t) the first component of the last acquired voltage is uα0(t) the second component of the last acquired voltage is uβ0(t)。
The first component difference value operator module calculates the difference value of the current voltage and the first component of the last collected voltage as u (t) -uα0(t)。
Adjusting the sub-module to the difference u (t) -uα0(t) is adjusted by an adjustment factor k, i.e. u (t) -uα0(t) multiplying the difference by a predetermined value k, the adjusted difference being k (u (t) -uα0(t)). In one embodiment of the present invention, k may be greater than 0 and not greater than 1.
The second component difference value operator module calculates k (u (t) -uα0(t)) and the second component u of the last acquired voltageβ0The difference of (t) is k (u (t) -uα0(t))-uβ0(t)。
Let the frequency of the circuit under test be ω.
The first product computation submodule computes k (u (t) -uα0(t))-uβ0The product of (t) and the frequency ω of the circuit under test is ω (k (u (t) -u)α0(t))-uβ0(t))。
The first integral calculation submodule calculates ω (k (u (t) -u) by laplace transformα0(t))-uβ0(t)) and taking the calculated integrated value as the first component of the current voltage.
The first component of the current voltage u (t) is represented as follows:
wherein, Uα(s) is a first component of the current voltage u (t) which is represented by a parameter which is a complex number s, ω is the frequency of the circuit to be tested, s is a Laplace transform operator, U(s) is the current voltage corresponding to the current voltage u (t) which is represented by the parameter which is the complex number s, k is an adjustment coefficient, and k is greater than 0 and not greater than 1.
The second integral calculation submodule calculates U through Laplace transformα(s) integration.
And the second product calculation submodule recalculates the product of the integral value obtained by integral calculation of the second integral calculation submodule and the frequency omega of the circuit to be measured, and the product value obtained by calculation is used as a second component of the current voltage.
The second component of the current voltage u (t) is represented as follows:
wherein, Uβ(s) is a second component of the current voltage u (t) expressed by a parameter of complex number s, and ω is the frequency of the circuit under testS is a laplace transform operator, u(s) is a current voltage represented by a parameter s corresponding to the current voltage u (t), and k is an adjustment coefficient.
In the vicinity of s ═ j ω, where j is the phase shift operator, there are
Uβ(s)＝s*Uα(s) (19)
Namely Uβ(s) to Uα(s) lags by 90. Namely, two output quantities U with the same amplitude and the same frequency but different phases by 90 degrees can be obtained through the processα(s) and Uβ(s) the effect of shifting the phase by 90 degrees is achieved.
The first difference is adjusted by the adjusting submodule, so that the calculation result is more accurate.
The process of calculating the first component and the second component of the present current is the same as the process of calculating the first component and the second component of the present voltage, which is not described herein again in the embodiments of the present invention, and reference may be specifically made to the process of calculating the first component and the second component of the present voltage.
The first component of the present current i (t) is represented as follows:
the second component of the present current i (t) is represented as follows:
wherein, Iα(s) is a first component of the present current I (t) expressed as a parameter with a complex number s, Iβ(s) is a second component of the current i (t) and expressed by a parameter of a complex number s, ω is the frequency of the circuit to be tested, s is a complex parameter of the laplace transform, i(s) is the current corresponding to the current i (t) and expressed by a parameter of a complex number s, and k is an adjustment coefficient.
In an embodiment of the present invention, the calculation module 203 of an embodiment of the present invention may be further configured to: and calculating the difference value of the product of the second component of the current voltage and the first component of the current and the product of the first component of the current voltage and the second component of the current, and taking the calculated difference value as the current reactive power of the target point to be measured.
q＝Uβ(s)*Iα(s)-Uα(s)*Iβ(s) (22)
Wherein q is the current reactive power of the target point to be measured, Uα(s)、Uβ(s)、Iα(s) and Iβ(s) a first component and a second component, respectively, of the present voltage u (t) and the present current i (t).
Compared with the Fourier measurement method in the prior art, the reactive power detection device has small calculated amount; compared with the digital phase-shifting measurement method in the prior art, the voltage and the current of the embodiment of the invention are both the current voltage and the current, the calculated reactive power is the current reactive power instead of the average reactive power, and the real-time performance is stronger; the reactive power detection device provided by the embodiment of the invention is less affected by harmonic waves, so that the detected reactive power error is smaller. Therefore, the reactive power detection device provided by the embodiment of the invention can reduce the calculation amount and error of reactive power detection and improve the real-time performance of reactive power detection.
In addition, in conjunction with the descriptions of fig. 1 and fig. 2, fig. 3 shows a second structural schematic diagram of the reactive power detection apparatus provided in the embodiment of the present invention. The voltage acquisition module 201 may be a voltage collector; the current collection module 202 may be a current collector; the number of the phase shift modules can be two, and the two phase shift modules are respectively a voltage phase shift module and a current phase shift module.
The voltage phase shift module comprises a first component difference value operator module, a second component difference value operator module, a first product calculation submodule, a first integral calculation submodule, a second integral calculation submodule and a second product calculation submodule which are respectively a first subtracter, a second subtracter, a first multiplier, a first integrator, a second integrator and a second multiplier.
The current phase shift module comprises a first component difference value operator module, a second component difference value operator module, a first product calculation submodule, a first integral calculation submodule, a second integral calculation submodule and a second product calculation submodule which are respectively a third subtracter, a fourth subtracter, a third multiplier, a third integrator, a fourth integrator and a fourth multiplier.
The calculation module 203 of the embodiment of the present invention may include: one multiplier for calculating the product of the second component of the present voltage and the first component of the present current, i.e., a fifth multiplier shown in fig. 3; another multiplier for calculating a product of the first component of the present voltage and the second component of the present current, i.e., a sixth multiplier shown in fig. 3; a subtractor, i.e., a fifth multiplier shown in fig. 3, for calculating a difference between a product of the second component of the present voltage and the first component of the present current and a product of the first component of the present voltage and the second component of the present current.
The input ends of the voltage collector and the current collector collect the current voltage and the current of a target point to be tested in a circuit to be tested in each subsystem in the wind power generation system.
And the subtraction input end and the subtracted input end of the first subtracter are respectively connected with the output end of the voltage collector and the output end of the first integrator.
The subtracting input end and the subtracted input end of the second subtracter are respectively connected with the output ends of the first subtracter and the second multiplier.
One input end of the first multiplier is connected with the output end of the second subtracter, and the other input end of the first multiplier receives the frequency of the circuit to be tested.
The input end and the output end of the first integrator are respectively connected with the output end of the first multiplier and the input end of the second integrator.
One input end of the second multiplier is connected with the output end of the second integrator, and the other input end of the second multiplier receives the frequency of the circuit to be tested.
And the subtraction input end and the subtracted input end of the third subtracter are respectively connected with the output end of the current collector and the output end of the third integrator.
And the subtracting input end and the subtracted input end of the fourth subtracter are respectively connected with the output ends of the third subtracter and the fourth multiplier.
One input end of the third multiplier is connected with the output end of the fourth subtracter, and the other input end of the third multiplier receives the frequency of the circuit to be tested.
The input end and the output end of the third integrator are respectively connected with the output end of the third multiplier and the input end of the third integrator.
One input end of the fourth multiplier is connected with the output end of the fourth integrator, and the other input end of the fourth multiplier receives the frequency of the circuit to be tested.
And two input ends of the fifth multiplier are respectively connected with the output ends of the second multiplier and the third integrator.
Two input ends of the sixth multiplier are respectively connected with the output ends of the fourth multiplier and the first integrator.
And the subtracting input end and the subtracted input end of the fifth subtracter are respectively connected with the output ends of the fifth multiplier and the sixth multiplier.
And the output end of the fifth subtracter outputs the reactive power obtained by calculation.
Compared with the Fourier measurement method in the prior art, the reactive power detection device provided by the embodiment of the invention has small calculated amount; compared with the digital phase-shifting measurement method in the prior art, the voltage and the current of the embodiment of the invention are both the current voltage and the current, the calculated reactive power is the current reactive power instead of the average reactive power, and the real-time performance is stronger; in addition, the reactive power detection method provided by the embodiment of the invention is less affected by harmonic waves, so that the detected reactive power error is smaller.
In one embodiment of the invention, the adjustment submodule may be an amplifier.
In one embodiment of the present invention, the voltage phase shift module may further include a first amplifier.
In one embodiment of the present invention, the current phase shift module may further include a second amplifier.
Of course, in one embodiment of the present invention, the voltage phase shift module may further include a first amplifier, and the current phase shift module may further include a second amplifier. As shown in fig. 4, fig. 4 is a schematic structural diagram illustrating a third reactive power detection apparatus provided in an embodiment of the present invention. In the embodiment of the present invention shown in fig. 4, based on the embodiment shown in fig. 3, the voltage phase shift module further includes a first amplifier, and the current phase shift module further includes a second amplifier.
In an embodiment of the present invention, the amplification factors of the first amplifier and the second amplifier may be greater than 0 and not greater than 1.
Compared with the Fourier measurement method in the prior art, the reactive power detection device provided by the embodiment of the invention has small calculated amount; compared with the digital phase-shifting measurement method in the prior art, the voltage and the current of the embodiment of the invention are both the current voltage and the current, the calculated reactive power is the current reactive power instead of the average reactive power, and the real-time performance is stronger; in addition, the reactive power detection method provided by the embodiment of the invention is less affected by harmonic waves, so that the detected reactive power error is smaller. And the accuracy of the reactive power detection can be further improved based on the amplifier.
It is to be understood that the invention is not limited to the specific arrangements and instrumentality described above and shown in the drawings. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present invention are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications and additions or change the order between the steps after comprehending the spirit of the present invention.
The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.
It should also be noted that the exemplary embodiments mentioned in this patent describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed simultaneously.
As described above, only the specific embodiments of the present invention are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.
Claims (8)
1. A reactive power detection apparatus, characterized in that the apparatus comprises: a voltage acquisition module, a current acquisition module, a phase shift module and a calculation module, wherein,
the voltage acquisition module and the current acquisition module are used for respectively and correspondingly acquiring the current voltage and the current of a target point to be measured in a circuit to be measured in each subsystem of the wind power generation system;
the phase shifting module is used for determining a first component and a second component of each of the current voltage and/or the current, wherein the second component is a component which is 90 degrees out of phase with the first component; the number of the phase shift modules is one when the phase shift modules are used for determining the first component and the second component of the current voltage and the current respectively, and the number of the phase shift modules is two when the phase shift modules are used for determining the first component and the second component of the current voltage or the current respectively;
the calculation module is used for calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and the current;
the phase shifting module comprises a first component difference value operator module, a second component difference value operator module, a first product calculating submodule, a first integral calculating submodule, a second integral calculating submodule and a second product calculating submodule; wherein the content of the first and second substances,
the first component difference value operator module is used for calculating a first difference value of the current voltage and a first component of the voltage collected last time, and/or calculating a second difference value of the current and the first component of the current collected last time;
the second component difference value operator module is configured to calculate a third difference value between the first difference value and the second component of the voltage acquired last time, and/or calculate a fourth difference value between the second difference value and the second component of the current acquired last time;
the first product calculation submodule is used for calculating a first product value of the third difference value and the frequency of the circuit to be detected and/or calculating a second product value of the fourth difference value and the frequency of the circuit to be detected;
the first integral calculation submodule is used for carrying out integral calculation on the first product value to obtain a first integral value and/or carrying out integral calculation on the second product value to obtain a second integral value, wherein the first integral value is used as a first component of the current voltage, and the second integral value is used as a first component of the current;
the second integral calculation submodule is used for carrying out integral calculation on the first integral value to obtain a third integral value and/or carrying out integral calculation on the second integral value to obtain a fourth integral value;
and the second product calculation sub-module is used for calculating a third product value of the third integral value and the frequency and/or calculating a fourth product value of the fourth integral and the frequency, wherein the third product value is used as a second component corresponding to the current voltage, and the fourth product value is used as a second component corresponding to the current.
2. The apparatus of claim 1, wherein the phase shift module further comprises an adjustment submodule configured to multiply the first difference and/or the second difference by a predetermined value to obtain an adjusted first difference and/or second difference, and output the adjusted first difference and/or second difference to the second component difference calculation submodule.
3. The apparatus of any of claims 1-2, wherein the computing module is further configured to:
and calculating the difference value of the product of the second component of the current voltage and the first component of the current and the product of the first component of the current voltage and the second component of the current, and taking the calculated difference value as the current reactive power of the target point to be measured.
4. The apparatus of claim 2, wherein the voltage acquisition module, the current acquisition module, the first component difference operator module, the second component difference operator module, the first product calculation sub-module, the first integral calculation sub-module, the second product calculation sub-module, and the adjustment sub-module correspond to a voltage collector, a current collector, a first subtractor, a second subtractor, a first multiplier, a first integrator, a second multiplier, and an amplifier, respectively.
5. The apparatus of claim 3, wherein the computing module comprises:
a multiplier for calculating the product of the second component of the present voltage and the first component of the present current;
another multiplier for calculating a product of the first component of the present voltage and the second component of the present current;
a subtractor for calculating a difference between a product of the second component of the present voltage and the first component of the present current and a product of the first component of the present voltage and the second component of the present current.
6. A method of reactive power detection, the method comprising:
the method comprises the steps that the current voltage and the current of a target point to be measured in a circuit to be measured in each subsystem in the wind power generation system are collected;
determining a first component and a second component of each of the present voltage and the present current, wherein the second component is a component that is 90 ° out of phase with respect to the first component;
calculating the current reactive power of the target point to be measured based on the respective first component and second component of the current voltage and the current;
the determining respective first and second components of the present voltage and the present current comprises:
calculating a first difference value of the current voltage and a first component of the last collected voltage, and a second difference value of the current and the first component of the last collected current;
calculating a third difference between the first difference and the last collected second component of voltage, and a fourth difference between the second difference and the last collected second component of current;
calculating a first product value of the third difference value and the frequency of the circuit to be tested, and a second product value of the fourth difference value and the frequency of the circuit to be tested;
performing an integral calculation on the first product value to obtain a first integral value, and performing an integral calculation on the second product value to obtain a second integral value, wherein the first integral value is used as a first component of the present voltage, and the second integral value is used as a first component of the present current;
performing integral calculation on the first integral value to obtain a third integral value, and performing integral calculation on the second integral value to obtain a fourth integral value;
calculating a third product value of the third integrated value and the frequency as a second component corresponding to the present voltage, and calculating a fourth product value of the fourth integral and the frequency as a second component corresponding to the present current.
7. The method of claim 6, further comprising, prior to said calculating a third difference between said first difference and said last collected second component of voltage, and a fourth difference between said second difference and said last collected second component of current:
and multiplying the first difference and/or the second difference by a preset value to obtain the adjusted first difference and/or second difference.
8. The method according to any one of claims 6 to 7, wherein the calculating the current reactive power of the target point to be measured based on the respective first and second components of the current voltage and current comprises:
and calculating the difference value of the product of the second component of the current voltage and the first component of the current and the product of the first component of the current voltage and the second component of the current, and taking the calculated difference value as the current reactive power of the target point to be measured.
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| DE59203277D1 (en) * | 1991-07-22 | 1995-09-21 | Landis & Gyr Betriebs Ag | Arrangement for measuring reactive power or reactive energy. |
| CN101063695B (en) * | 2007-06-12 | 2010-09-29 | 北京中星微电子有限公司 | Reactive power calculating circuit and method |
| US8350558B2 (en) * | 2008-10-03 | 2013-01-08 | Analog Devices, Inc. | System and method for measuring reactive power |
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