阅读说明：本技术 一种动态测量非线性负载阻抗的方法 (Method for dynamically measuring nonlinear load impedance ) 是由 王映品 李林 李志波 王德波 曾丽娜 李功捷 孙丽 崔相雨 于 2020-12-31 设计创作，主要内容包括：本发明提出了一种动态测量非线性负载阻抗的方法,包括：第一步：检测负载电压与电流；第二步：检测负载电压相角；第三步：ABC相电压进行dq坐标变换和ABC相电流进行dq坐标变换；第四步：第三步中ABC相电压进行dq坐标变换进行滤波,第三步中ABC相电流进行dq坐标变换进行滤波；第五步：得出相位和幅值,第六步：根据第五步中ABC相电压进行dq坐标变换进行滤波之后得出相位和幅值以及ABC相电流进行dq坐标变换进行滤波之后得出相位和幅值得到电阻值、电感值、电容值和阻抗角,借此,本发明具有能够适用于线性/非线性负载、有电力电子装置的负载,在电压频率发生变化时也适用,能够准确计算负载的等效电阻、电感、电容及阻抗角的优点。(The invention provides a method for dynamically measuring nonlinear load impedance, which comprises the following steps: the first step is as follows: detecting load voltage and current; the second step is that: detecting a load voltage phase angle; the third step: carrying out dq coordinate transformation on ABC phase voltage and carrying out dq coordinate transformation on ABC phase current; the fourth step: carrying out dq coordinate transformation on the ABC phase voltage for filtering in the third step, and carrying out dq coordinate transformation on the ABC phase current for filtering in the third step; the fifth step: obtaining the phase and the amplitude, and a sixth step: and carrying out dq coordinate transformation according to the ABC phase voltage in the fifth step, filtering to obtain a phase and an amplitude, carrying out dq coordinate transformation on the ABC phase current, filtering to obtain a phase and an amplitude, and obtaining a resistance value, an inductance value, a capacitance value and an impedance angle.)

1. A method for dynamically measuring a nonlinear load impedance, comprising:

the first step is as follows: detecting load voltage and current;

the second step is that: detecting a load voltage phase angle;

the third step: carrying out dq coordinate transformation on ABC phase voltage and carrying out dq coordinate transformation on ABC phase current;

the fourth step: carrying out dq coordinate transformation on the ABC phase voltage for filtering in the third step, and carrying out dq coordinate transformation on the ABC phase current for filtering in the third step;

the fifth step: carrying out dq coordinate transformation on the ABC phase voltage in the fourth step, filtering to obtain a phase and an amplitude, and carrying out dq coordinate transformation on the ABC phase current in the fourth step, filtering to obtain a phase and an amplitude;

and a sixth step: and carrying out dq coordinate transformation according to the ABC phase voltage in the fifth step, filtering, obtaining the phase and the amplitude, carrying out dq coordinate transformation on the ABC phase current, filtering, obtaining the phase and the amplitude, and obtaining the resistance value, the inductance value, the capacitance value and the impedance angle.

2. A method of dynamically measuring the impedance of a nonlinear load as recited in claim 1 wherein the measuring method comprises using a measuring circuit.

3. The method of claim 2, wherein the measurement circuit comprises a voltage input point and a current input point of the load.

4. The method of claim 3, wherein a voltage phase detector is electrically connected to the voltage input point, one end of the voltage phase detector is electrically connected to an abc coordinate to dq coordinate converter, the voltage input point is electrically connected to the abc coordinate to dq coordinate converter, the other end of the abc coordinate to dq coordinate converter is electrically connected to two filters and an equivalent voltage amplitude calculator, the other ends of the filters and the equivalent voltage amplitude calculator are electrically connected to a voltage phase calculator, the other end of the voltage amplitude calculator is also electrically connected to a filter, the other ends of the two filters are electrically connected to an equivalent impedance value calculator, the other end of the voltage phase calculator is electrically connected to an adder, and the other ends of the adder and the equivalent impedance value calculator are electrically connected to a resistance output part and an inductance output part, an inductance value output part and a capacitance value output part are electrically connected between the inductance value output parts, and one end of the adder is also electrically connected with an impedance phase angle output part.

5. The method as claimed in claim 4, wherein an abc coordinate to dq coordinate converter is electrically connected to the current input point, the voltage phase detector is electrically connected to the abc coordinate to dq coordinate converter, an equivalent current amplitude calculator and two filters are electrically connected to the other end of the abc coordinate to dq coordinate converter, the other end of the equivalent current amplitude calculator is electrically connected to the filter, the other end of the filter is electrically connected to the equivalent impedance value calculator, the other end of the two filters is electrically connected to the current phase calculator, and the other end of the current phase calculator is electrically connected to the adder.

6. The method of claim 5, wherein the operation procedure in the equivalent voltage amplitude calculator is as follows: sqrt (u (1) ^2+ u (2) ^ 2).

7. The method of claim 5, wherein the equivalent current amplitude calculator comprises the following steps: sqrt (u (1) ^2+ u (2) ^ 2).

8. The method of claim 5, wherein the operation procedure in the current phase calculator is as follows: atan (u (2)/u (1)).

9. The method of claim 4, wherein the ABC-coordinate-to-dq-coordinate converter implements a dq transformation of the ABC phase voltages.

10. The method of claim 5, wherein the ABC-coordinate-to-dq-coordinate transformer, ABC, phase current is dq-coordinate transformed.

Technical Field

The invention belongs to the technical field of load impedance measurement, and particularly relates to a method for dynamically measuring nonlinear load impedance.

Background

At present, chinese patent 202010006096.8 proposes a method and an apparatus for obtaining a load impedance angle, which eliminate an error caused by delay by filtering a load voltage and a load current at the same time, and obtain the load impedance angle by calculation in combination with load impedance properties, thereby ensuring accuracy of a result, but this method only obtains the load impedance angle, and chinese patent 202010125688.1 proposes a method and an apparatus for predicting a microgrid adaptive anti-islanding disturbance load impedance value, which are complex in algorithm for calculating the load impedance by using a neural network method, and require 30 times of simulation for long operation time, and chinese patent 10448127.X discloses a load impedance measurement system and a method that can only be applied to a linear load of a pure resistor.

Disclosure of Invention

The invention provides a method for dynamically measuring nonlinear load impedance, which can be suitable for linear/nonlinear loads and loads with power electronic devices and is also suitable for voltage frequency change. The equivalent resistance, inductance, capacitance and impedance angle of the load can be accurately calculated.

The technical scheme of the invention is realized as follows: a method of dynamically measuring a nonlinear load impedance, comprising:

the first step is as follows: detecting load voltage and current;

the second step is that: detecting a load voltage phase angle;

the third step: carrying out dq coordinate transformation on ABC phase voltage and carrying out dq coordinate transformation on ABC phase current;

the fourth step: carrying out dq coordinate transformation on the ABC phase voltage for filtering in the third step, and carrying out dq coordinate transformation on the ABC phase current for filtering in the third step;

the fifth step: carrying out dq coordinate transformation on the ABC phase voltage in the fourth step, filtering to obtain a phase and an amplitude, and carrying out dq coordinate transformation on the ABC phase current in the fourth step, filtering to obtain a phase and an amplitude;

and a sixth step: and carrying out dq coordinate transformation according to the ABC phase voltage in the fifth step, filtering, obtaining the phase and the amplitude, carrying out dq coordinate transformation on the ABC phase current, filtering, obtaining the phase and the amplitude, and obtaining the resistance value, the inductance value, the capacitance value and the impedance angle.

As a preferred embodiment, the measuring method comprises using a measuring circuit.

As a preferred embodiment, the measuring circuit comprises a voltage input and a current input of the load.

As a preferred embodiment, a voltage phase detector is electrically connected to the voltage input point, one end of the voltage phase detector is electrically connected to the abc coordinate to dq coordinate converter, the voltage input point is electrically connected to the abc coordinate to dq coordinate converter, the other end of the abc coordinate to dq coordinate converter is electrically connected to two filters and an equivalent voltage amplitude calculator in sequence, the other ends of the filters and the equivalent voltage amplitude calculator are electrically connected to a voltage phase calculator, the other end of the voltage amplitude calculator is also electrically connected to a filter, the other ends of the two filters are electrically connected to an equivalent impedance value calculator, the other end of the voltage phase calculator is electrically connected to an adder, the other ends of the adder and the equivalent impedance value calculator are electrically connected to a resistance value output part and an inductance value output part, and the capacitance value output part are electrically connected between the inductance value output part and the capacitance value output part, one end of the adder is also electrically connected with an impedance phase angle output part.

As a preferred embodiment, an abc coordinate to dq coordinate converter is electrically connected to the current input point, the voltage phase detector is electrically connected to the abc coordinate to dq coordinate converter, an equivalent current amplitude calculator and two filters are electrically connected to the other end of the abc coordinate to dq coordinate converter in sequence, the other end of the equivalent current amplitude calculator is electrically connected to the filter, the other end of the filter is electrically connected to the equivalent impedance value calculator, the other ends of the two filters are electrically connected to the current phase calculator, and the other end of the current phase calculator is electrically connected to the adder.

As a preferred embodiment, the operation process in the equivalent voltage amplitude calculator is as follows: sqrt (u (1) ^2+ u (2) ^ 2).

As a preferred embodiment, the operation process in the equivalent current amplitude calculator is as follows: sqrt (u (1) ^2+ u (2) ^ 2).

As a preferred embodiment, the operation process in the current phase calculator is as follows: atan (u (2)/u (1)).

In a preferred embodiment, the ABC coordinate-to-dq coordinate converter performs dq coordinate conversion on ABC phase voltages.

In a preferred embodiment, an ABC-coordinate-to-dq-coordinate transformer ABC performs dq-coordinate transformation on phase current.

After the technical scheme is adopted, the invention has the beneficial effects that:

the method has the advantages of simple calculation, good real-time performance and the like, can be suitable for linear/nonlinear loads and loads with power electronic devices, and is also suitable for voltage frequency change. The equivalent resistance, the inductance, the capacitance and the impedance angle of the load can be accurately calculated, and the equivalent impedance of the nonlinear load is obtained by combining dq coordinate transformation and a filtering technology.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic flow chart of the present invention;

FIG. 3 is a schematic diagram of a resistance output portion of FIG. 1;

FIG. 4 is a schematic diagram of a portion of the inductive reactance value output of FIG. 1;

FIG. 5 is a schematic diagram of the structure of the output portion of the inductance values in FIG. 1;

FIG. 6 is a schematic diagram of a capacitance output portion of FIG. 1;

FIG. 7 is a schematic diagram of the impedance phase angle output portion of FIG. 1;

FIG. 8 is a schematic diagram of a portion of the voltage phase detector of FIG. 1;

FIG. 9 is a schematic diagram of a portion of the abc-to-dq-coordinate converter of FIG. 1;

FIG. 10 is a schematic diagram of a portion of the filter of FIG. 1;

FIG. 11 is a schematic diagram of a portion of the equivalent voltage amplitude calculator of FIG. 1;

FIG. 12 is a schematic diagram of a portion of the equivalent current amplitude calculator of FIG. 1;

FIG. 13 is a schematic diagram of a portion of the voltage phase calculator of FIG. 1;

FIG. 14 is a schematic diagram of a portion of the current phase calculator of FIG. 1;

fig. 15 is a schematic diagram of a part of the equivalent impedance value calculator in fig. 1.

In the figure, PLL-voltage phase detector; a2d-abc coordinate to dq coordinate converter, add-adder; filtering 1-6: a filter; a UL-equivalent voltage amplitude calculator; an IL-equivalent current amplitude calculator; phi 1-voltage phase calculator; phi-a current phase calculator; ZL-equivalent impedance value calculator.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 15, a method for dynamically measuring a nonlinear load impedance includes:

the first step is as follows: detecting load voltage and current;

the second step is that: detecting a load voltage phase angle;

the third step: carrying out dq coordinate transformation on ABC phase voltage and carrying out dq coordinate transformation on ABC phase current;

the fourth step: carrying out dq coordinate transformation on the ABC phase voltage for filtering in the third step, and carrying out dq coordinate transformation on the ABC phase current for filtering in the third step;

the fifth step: carrying out dq coordinate transformation on the ABC phase voltage in the fourth step, filtering to obtain a phase and an amplitude, and carrying out dq coordinate transformation on the ABC phase current in the fourth step, filtering to obtain a phase and an amplitude;

and a sixth step: and carrying out dq coordinate transformation according to the ABC phase voltage in the fifth step, filtering, obtaining the phase and the amplitude, carrying out dq coordinate transformation on the ABC phase current, filtering, obtaining the phase and the amplitude, and obtaining the resistance value, the inductance value, the capacitance value and the impedance angle.

The measurement method includes using a measurement circuit. The measuring circuit comprises a voltage input point and a current input point of the load. The voltage phase detector is electrically connected to a voltage input point, one end of the voltage phase detector is electrically connected with an abc coordinate to dq coordinate converter, the voltage input point is electrically connected with the abc coordinate to dq coordinate converter, the other end of the abc coordinate to dq coordinate converter is electrically connected with two filters and an equivalent voltage amplitude calculator in sequence, the other ends of the filters and the equivalent voltage amplitude calculator are electrically connected with the voltage phase calculator, the other end of the voltage amplitude calculator is also electrically connected with the filters, the other ends of the two filters are electrically connected with an equivalent impedance value calculator, the other end of the voltage phase calculator is electrically connected with an adder, the other ends of the adder and the equivalent impedance value calculator are electrically connected with a resistance value output part and an inductance value output part, an inductance value output part and a capacitance value output part are electrically connected between the inductance value output parts, and one end of the adder is also electrically.

The current input point is electrically connected with an abc coordinate to dq coordinate converter, the voltage phase detector is electrically connected with the abc coordinate to dq coordinate converter, the other end of the abc coordinate to dq coordinate converter is electrically connected with an equivalent current amplitude calculator and two filters in sequence, the other end of the equivalent current amplitude calculator is electrically connected with the filters, the other end of each filter is electrically connected with an equivalent impedance value calculator, the other ends of the two filters are electrically connected with a current phase calculator, and the other end of each current phase calculator is electrically connected with the adder.

The operation process in the equivalent voltage amplitude calculator is as follows: sqrt (u (1) ^2+ u (2) ^ 2). The operation process in the equivalent current amplitude calculator is as follows: sqrt (u (1) ^2+ u (2) ^ 2). The operation process in the current phase calculator is as follows: atan (u (2)/u (1)). The ABC coordinate-to-dq coordinate converter is used for realizing dq coordinate conversion of ABC phase voltages. and an ABC coordinate-to-dq coordinate converter ABC performs dq coordinate conversion on the phase current.

The method has the advantages of simple calculation, good real-time performance and the like, can be suitable for linear/nonlinear loads and loads with power electronic devices, and is also suitable for voltage frequency change. The equivalent resistance, the inductance, the capacitance and the impedance angle of the load can be accurately calculated, and the equivalent impedance of the nonlinear load is obtained by combining dq coordinate transformation and a filtering technology.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.