CN100419436C - A four-quadrant power measurement method - Google Patents

Abstract

The invention discloses a method for measuring power, that is, a four-quadrant power measurement method, which overcomes the defect that the existing method is only applicable to the power measurement of an electric energy metering point whose power transmission direction is determined such as an electric port or a power supply port. And inaccurate power measurement or poor anti-interference ability, large amount of calculation and other shortcomings. The steps are: after the device is started, set the number of sampling points N and the sampling frequency f _s in one cycle; get the voltage sampling value sequence u(n) and current sampling value sequence i(n) in one cycle after sampling; for u(n ) and i(n) are respectively subjected to discrete Fourier transform to obtain (k) and (k); according to (k) and (k), the active power P and reactive power Q are directly calculated using the formula; according to the active power Power P and reactive power Q calculate apparent power S and power factor λ; determine the power state according to the sign of P and Q. The method considers the magnitude of the power value and the direction of power transmission at the same time, and is suitable for the power measurement of electric energy metering points where the direction of power transmission is determined and changed, and the method has accurate measurement, strong anti-interference ability, and small calculation amount.

Description

A four-quadrant power measurement method

Technical field:

The invention relates to a method of measuring power.

Background technique:

Most of the current power measurement methods are only used to measure the power value, and generally do not give the power transmission direction. They are only applicable to the power measurement of the power consumption port or the power supply port, and are not suitable for the electric energy metering point where the power transmission direction changes. Power measurement, such as the invention patent application with the publication number CN1067744A and the name "Method and Device for Measuring Power and Electric Energy", thus cannot reflect the real power state of the electric energy metering point, and some equipment that sometimes uses electricity and sometimes generates electricity, It needs to measure its instantaneous real power state, and the existing measurement methods cannot complete these functions; on the other hand, the current power measurement methods also have defects such as inaccurate measurement, poor anti-interference ability, and large amount of calculation.

Invention content:

和变换后电流序列值

$\left\{\begin{array}{c}U\left(k\right)=U_{\mathrm{Rk}}+j{U}_{\mathrm{Ik}}\\ I\left(k\right)=I_{\mathrm{Rk}}+j{I}_{\mathrm{Ik}}\end{array}\right.$ 104，式中，

为复数，分别表示电压、电流采样值序列u(n)、i(n)的离散傅里叶变换后的第k次电压、电流分量，U_Rk、U_Ik分别为第k次电压分量的实部与虚部，I_Rk、I_Ik分别为第k次电流分量的实部与虚部，k＝0，1，2，..，N-1；根据变换后电压序列值

和变换后电流序列值

利用公式 $\left\{\begin{array}{c}P=U_{R0}{I}_{R0}+\frac{2}{N^2}\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}[U_{\mathrm{Rk}}\·I_{\mathrm{Rk}}+U_{\mathrm{Ik}}\·I_{\mathrm{Ik}}]\\ Q=\frac{2}{N^2}\underset{k=1}{\overset{N-1}{\mathrm{\Σ}}}[U_{\mathrm{Ik}}\·I_{\mathrm{Rk}}-U_{\mathrm{Rk}}\·I_{\mathrm{Ik}}]\end{array}\right.$ 计算有功功率P和无功功率Q 105；根据有功功率P和无功功率Q计算视在功率S和功率因数λ106；根据有功功率P、无功功率Q的正负号确定功率状态107；然后返回步骤103的起始端完成下一周期的功率测量。本发明的四象限功率测量方法的特点在于，从矢量的角度对功率进行测量，考虑有功功率、无功功率的数值大小和传输方向，唯一确定了电能交换的真实状态和数值，既适用于功率传输方向确定的电能计量点的功率测量，也适用于功率传输方向变化的电能计量点的功率测量；由于本发明的方法采用了傅里叶变换，变换过程中可虑除高频干扰信号，因此测量准确、抗干扰能力强，在计算过程中使用了专门的公式，计算量小，得到的数值准确，除采样电路外均采用纯软件计算方法，功率状态直接由有功功率和无功功率的正负号确定，不需要测量阻抗角大小，减少了硬件成本，可广泛用于数字式功率测量设备。The purpose of the present invention is to provide a four-quadrant power measurement method, to overcome the existing power measurement method is only applicable to the power measurement point of the electric energy metering point determined by the power transmission direction of the electric port or the power supply port, and the power measurement Inaccurate or poor anti-interference ability, large amount of calculation and other deficiencies. The steps of the method of the present invention are as follows: start the measuring device 101; set the number of sampling points N and the sampling frequency f _s 102 in a measurement period; obtain the voltage sampling value sequence u(n) and the current sampling value sequence i in a measurement period through sampling (n) 103; Discrete Fourier transform is performed on the voltage sampled value sequence u(n) and the current sampled value sequence i(n), respectively, to obtain the transformed voltage sequence value

and the transformed current sequence value

$\left\{\begin{array}{c}u\left(k\right)=u_{\mathrm{Rk}}+j{u}_{\mathrm{Ik}}\\ I\left(k\right)=I_{\mathrm{Rk}}+j{I}_{\mathrm{<figure-callout\; id="104"\; label="Ik"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">Ik</figure-callout>}}\end{array}\right.$ 104, where,

is a complex number, respectively representing the kth voltage and current components after the discrete Fourier transform of the voltage and current sampling value sequences u(n) and i(n), U _Rk and U _Ik are the real values of the kth voltage components respectively part and imaginary part, I _Rk , I _Ik are the real part and imaginary part of the kth current component respectively, k=0, 1, 2, .., N-1; according to the transformed voltage sequence value

and the transformed current sequence value

use the formula $\left\{\begin{array}{c}P=u_{R0}{I}_{R0}+\frac{2}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">N</figure-callout>}}^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[u_{\mathrm{Rk}}\&CenterDot;I_{\mathrm{Rk}}+u_{\mathrm{Ik}}\&CenterDot;I_{\mathrm{Ik}}]\\ Q=\frac{2}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">N</figure-callout>}}^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[u_{\mathrm{Ik}}\&Center\; Dot;I_{\mathrm{Rk}}-u_{\mathrm{Rk}}\&Center\; Dot;I_{\mathrm{Ik}}]\end{array}\right.$ Calculate active power P and reactive power Q 105; calculate apparent power S and power factor λ106 according to active power P and reactive power Q; determine power status 107 according to the sign of active power P and reactive power Q; then return The initiator of step 103 completes the power measurement of the next cycle. The characteristic of the four-quadrant power measurement method of the present invention is that the power is measured from the angle of the vector, and the numerical value and transmission direction of the active power and the reactive power are considered, and the real state and value of the electric energy exchange are uniquely determined, which is suitable for power The power measurement of the electric energy metering point whose transmission direction is determined is also suitable for the power measurement of the electric energy metering point whose power transmission direction changes; because the method of the present invention adopts Fourier transform, high-frequency interference signals can be considered in the transformation process, so Accurate measurement, strong anti-interference ability, special formula is used in the calculation process, the calculation amount is small, and the obtained value is accurate. Except for the sampling circuit, the pure software calculation method is used. The power state is directly determined by the active power and reactive power. The negative sign is determined, the size of the impedance angle does not need to be measured, the hardware cost is reduced, and it can be widely used in digital power measuring equipment.

Description of drawings:

Fig. 1 is a schematic flow chart of the method of the present invention, Fig. 2 is a four-quadrant power state distribution diagram in Embodiment 2, and Fig. 3 is a circuit of voltage sampling circuit 1, current sampling circuit 2 and analog/digital conversion circuit 3 in Embodiment 1 Schematic.

Detailed ways:

和变换后电流序列值

$\left\{\begin{array}{c}\stackrel{.}{U}\left(k\right)=U_{\mathrm{Rk}}+j{U}_{\mathrm{Ik}}\\ \stackrel{.}{I}\left(k\right)=I_{\mathrm{Rk}}+j{I}_{\mathrm{Ik}}\end{array}\right.$ 104，式中，

为复数，分别表示电压、电流采样值序列u(n)、i(n)的离散傅里叶变换后的第k次电压、电流分量，U_Rk、U_Ik分别为第k次电压分量的实部与虚部，I_Rk、I_Ik分别为第k次电流分量的实部与虚部，k＝0，1，2，.，N-1；根据变换后电压序列值

和变换后电流序列值

利用公式 $\left\{\begin{array}{c}P=U_{R0}{I}_{R0}+\frac{2}{N^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[U_{\mathrm{Rk}}\&CenterDot;I_{\mathrm{Rk}}+U_{\mathrm{Ik}}\&CenterDot;I_{\mathrm{Ik}}]\\ Q=\frac{2}{N^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[U_{\mathrm{Ik}}\&CenterDot;I_{\mathrm{Rk}}-U_{\mathrm{Rk}}\&CenterDot;I_{\mathrm{Ik}}]\end{array}\right.$ 计算有功功率P和无功功率Q 105；根据有功功率P和无功功率Q计算视在功率S和功率因数λ106；根据有功功率P、无功功率Q和功率因数λ的正负号确定功率状态107；然后返回步骤103的起始端完成下一周期的功率测量。在本发明中：Specific Embodiment 1: The present embodiment will be specifically described below with reference to FIG. 1 . The present embodiment consists of the following steps: start the measuring device 101; set the number of sampling points N and the sampling frequency f _s in a measurement cycle, the set sampling frequency f _s is greater than or equal to twice the highest frequency of the measured alternating current (satisfying Shannon sampling Theorem), a measurement cycle is an integer multiple of the measured AC fundamental wave cycle 102; the voltage sample value sequence u(n) and current sample value sequence i(n) 103 in a measurement cycle are obtained through sampling; the voltage sample value sequence Discrete Fourier transform is performed on u(n) and current sampling value sequence i(n) respectively to obtain the transformed voltage sequence value

and the transformed current sequence value

$\left\{\begin{array}{c}\stackrel{.}{u}\left(k\right)=u_{\mathrm{Rk}}+j{u}_{\mathrm{Ik}}\\ \stackrel{.}{I}\left(k\right)=I_{\mathrm{Rk}}+\mathrm{<figure-callout\; id="104"\; label="j\; I\; Ik"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">j</figure-callout>}{I}_{\mathrm{Ik}}{}_{}\end{array}\right.$ 104, where,

is a complex number, respectively representing the kth voltage and current components after the discrete Fourier transform of the voltage and current sampling value sequences u(n) and i(n), U _Rk and U _Ik are the real values of the kth voltage components respectively Part and imaginary part, I _Rk , I _Ik are the real part and imaginary part of the kth current component respectively, k=0, 1, 2, ., N-1; according to the voltage sequence value after transformation

and the transformed current sequence value

use the formula $\left\{\begin{array}{c}P=u_{R0}{I}_{R0}+\frac{2}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">N</figure-callout>}}^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[u_{\mathrm{Rk}}\&CenterDot;I_{\mathrm{Rk}}+u_{\mathrm{Ik}}\&Center\; Dot;I_{\mathrm{Ik}}]\\ Q=\frac{2}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">N</figure-callout>}}^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[u_{\mathrm{Ik}}\&CenterDot;I_{\mathrm{Rk}}-u_{\mathrm{Rk}}\&CenterDot;I_{\mathrm{Ik}}]\end{array}\right.$ Calculate active power P and reactive power Q 105; calculate apparent power S and power factor λ106 according to active power P and reactive power Q; determine power status according to the sign of active power P, reactive power Q and power factor λ 107; then return to the beginning of step 103 to complete the power measurement of the next cycle. In the present invention:

(1) Sampling the voltage and current with a suitable sampling frequency to obtain a sequence of voltage sampling values u(n) and a sequence of current sampling values i(n) (n=0, 1, 2, ..., N-1, N is the number of sampling points in one cycle).

(2) Carry out discrete Fourier transform according to formula (1) to voltage sampling value sequence u (n) and current sampling value sequence i (n), obtain the transformation result shown in formula (2):

$\left\{\begin{array}{c}\stackrel{<span\; class="notranslate">\; .</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">j</figure-callout></span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; k\; n</span>}}\\ \stackrel{<span\; class="notranslate">\; .</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">j</figure-callout></span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; k\; n</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\left\{\begin{array}{c}\stackrel{<span\; class="notranslate">\; .</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; Rk</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; Ik</span>}}\\ \stackrel{<span\; class="notranslate">\; .</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Rk</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Ik</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

为复数，分别表示电压、电流采样值序列u(n)、i(n)的离散傅里叶变换后的第k次电压、电流分量；U_Rk、U_Ik分别为第k次电压分量的实部与虚部；I_Rk、I_Ik分别为第k次电流分量的实部与虚部；k＝0，1，2，，N-1。In the formula,

is a complex number, respectively representing the kth voltage and current components after the discrete Fourier transform of the voltage and current sampling value sequences u(n) and i(n); U _Rk and U _Ik are the real values of the kth voltage components respectively part and imaginary part; I _Rk , I _Ik are the real part and imaginary part of the kth current component respectively; k=0, 1, 2,, N-1.

(3) According to the Fourier transform results of the voltage sampling value sequence u(n) and the current sampling value sequence i(n) represented by the formula (2), calculate the active power P and the reactive power Q according to the formula (3):

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">N</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; Rk</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Rk</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; Ik</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Ik</span>}}<span\; class="notranslate">\; ]</span>\\ \mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">N</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; Ik</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Rk</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; Rk</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; Ik</span>}}<span\; class="notranslate">\; ]</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

(4) After the active power P and reactive power Q are calculated by the formula (3), the apparent power S and the power factor λ are calculated according to the formula (4) (where -1≤λ≤1):

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="P"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">P</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Q"\; filenames="C20051001014000111.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ \mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

(5) The active power and reactive power calculated according to the formula (3) are signed, the positive sign indicates the absorbed power, and the negative sign indicates the output power.

In step 103 , the voltage and current are collected by the voltage sampling circuit 1 , the current sampling circuit 2 and the analog/digital conversion circuit 3 . Voltage sampling circuit 1 consists of voltage transformer PT1, No. 1 integrated operational amplifier A1, No. 2 integrated operational amplifier A2, No. 1 resistor R81, No. 2 resistor R82, No. 3 resistor R83, No. 4 resistor R84, No. 5 resistor R85 and No. 6 Composed of resistance R86, the voltage transformer PT1 is a voltage input, voltage output type voltage converter, the two ends of the primary side are connected to the two ends of the measured circuit port, one end of the secondary side of the voltage transformer PT1 is grounded, and the other end Connect one end of the No. 4 resistor R84, the other end of the No. 4 resistor R84 is connected to the non-inverting input terminal of the No. 1 integrated operational amplifier A1 and one end of the No. 2 resistor R82, and the inverting input end of the No. 1 integrated operational amplifier A1 is connected to the No. 3 resistor R83 One end of the first resistor R81 and one end of the first resistor R81, the other end of the third resistor R83 is grounded, the other end of the first resistor R81 is connected to the output end of the first integrated operational amplifier A1 and one end of the fifth resistor R85, and the other end of the second resistor R82 One end is connected to the output terminal of No. 2 integrated operational amplifier A2, one end of No. 6 resistor R86 and the inverting input terminal of No. 2 integrated operational amplifier A2; the current sampling circuit 2 is composed of current transformer CT1, No. 3 integrated operational amplifier A3, and No. 4 Integrated operational amplifier A4, No. 7 resistor R87, No. 8 resistor R88, No. 9 resistor R89, No. 10 resistor R90, No. 11 resistor R91 and No. 12 resistor R92. The current transformer CT1 is a current input and voltage output type current transformer. Converter, its primary side is connected in series with the measured circuit, one end of the secondary side of the current transformer CT1 is grounded, the other end is connected to one end of No. 10 resistor R90, and the other end of No. 10 resistor R90 is connected to the same phase of No. 3 integrated operational amplifier A3 The input end and one end of No. 8 resistor R88, the inverting input end of No. 3 integrated operational amplifier A3 connect one end of No. 7 resistor R87 and one end of No. 9 resistor R89, the other end of No. 9 resistor R89 is grounded, and the The other end is connected to the output terminal of No. 3 integrated operational amplifier A3 and one end of No. 11 resistor R91, and the other end of No. 8 resistor R88 is connected to the output terminal of No. 4 integrated operational amplifier A4, one end of No. 12 resistor R92 and No. 4 integrated The inverting input terminal of the operational amplifier A4; the analog/digital conversion circuit 3 is composed of the analog/digital conversion chip U15 whose model is ADS8364Y, the pin 63 of the analog/digital conversion chip U15 is connected to the other end of the fifth resistor R85, and the analog/digital conversion The pin 64 of the chip U15 is connected to the other end of the No. 6 resistor R86, the pin 2 of the A/D conversion chip U15 is connected to the other end of the No. 11 resistor R91, and the pin 1 of the A/D conversion chip U15 is connected to the other end of the No. 12 resistor R92 At one end, the pin 61 of the A/D conversion chip U15 is connected to the non-inverting input terminal of the fourth integrated operational amplifier A4 and the non-inverting input terminal of the second integrated operational amplifier A2. When working, the pin 61 of the analog/digital conversion chip U15 provides a reference voltage of 2.5 volts to the non-inverting input terminal of the No. 2 integrated operational amplifier A2 and the non-inverting input terminal of the No. The No. 12 resistor sets the appropriate resistance value to convert the bipolar voltage range of the secondary side of the voltage transformer PT1 and current transformer CT1 into the unipolar voltage range required for the normal operation of the analog/digital conversion chip U15 0～+ 5V, so that the analog/digital conversion circuit 3 can handle it.

功率因数λ的值为正；如果有功功率P为负、无功功率Q为正，则象限分布为第II象限，被测设备为供电状态，对应的复阻抗为容性，输出有功功率的同时吸收无功功率，阻抗角

的范围是功率因数λ的值为负；如果有功功率P为负、无功功率Q为负，则象限分布为第III象限，被测设备为供电状态，对应的复阻抗为感性，输出有功功率的同时输出无功功率，阻抗角

的范围是

功率因数λ的值为负；如果有功功率P为正、无功功率Q为负，则象限分布为第IV象限，被测设备为用电状态，对应的复阻抗为容性，吸收有功功率的同时输出无功功率，阻抗角

的范围是

功率因数λ的值为正。Specific Embodiment 2: The present embodiment will be specifically described below in conjunction with FIG. 2 and Table 1. Step 107 in the first embodiment determines the power state of the device under test through the following steps in this embodiment: if the active power P is positive and the reactive power Q is positive, then the quadrant distribution is the I quadrant, and the device under test is the power consumption state, the corresponding complex impedance is inductive, absorbing active power and absorbing reactive power at the same time, the impedance angle range is

The value of the power factor λ is positive; if the active power P is negative and the reactive power Q is positive, the quadrant distribution is the second quadrant, the device under test is in the power supply state, and the corresponding complex impedance is capacitive, and the active power is output at the same time Absorbed reactive power, impedance angle

range is The value of the power factor λ is negative; if the active power P is negative and the reactive power Q is negative, the quadrant distribution is the third quadrant, the device under test is in the power supply state, and the corresponding complex impedance is inductive, and the active power is output at the same time Reactive power, impedance angle

range is

The value of the power factor λ is negative; if the active power P is positive and the reactive power Q is negative, the quadrant distribution is the fourth quadrant, the equipment under test is in the state of power consumption, and the corresponding complex impedance is capacitive, absorbing active power. Simultaneously output reactive power, impedance angle

range is

The value of the power factor λ is positive.

S-I, S-II, S-III, and S-IV in Table 1 of this embodiment represent four different power states of electric energy metering points where the power transmission direction changes, and their meanings are as follows:

S-I——absorb reactive power while absorbing active power (inductive, P is positive, Q is positive);

S-II——output active power while absorbing reactive power (capacitive, P is negative, Q is positive);

S-III——output reactive power while outputting active power (inductive, P is negative, Q is negative);

S-IV——to output reactive power while absorbing active power (capacitive, P is positive, Q is negative).

时，功率状态为只吸收有功功率；阻抗角

时，功率状态为只吸收无功功率；阻抗角

时，功率状态为只输出有功功率；阻抗角时，功率状态为只输出无功功率。本发明中，首先由实施方式一计算得到有功功率P和无功功率Q，然后根据有功功率P、无功功率Q的正负号并参照实施方式二中的表1确定功率状态。功率状态主要包括供用电方向、象限分布、阻抗角范围、复阻抗性质、有功功率方向、无功功率方向、功率因数方向。这里，对一些参数作如下定义：Among them, both the I and IV quadrants represent the power state when used as a power port, that is, the active power is absorbed. The difference is that the complex impedance corresponding to the power state of the I quadrant is inductive and absorbs reactive power. The impedance is capacitive, outputting reactive power; both the II and III quadrants indicate the power state when used as a power supply port, that is, the output active power, the difference is that the complex impedance corresponding to the power state of the second quadrant is capacitive, absorbing reactive power, The complex impedance corresponding to the power state of the third quadrant is inductive, and the reactive power is output. In particular, the impedance angle

, the power state is only absorbing active power; the impedance angle

, the power state is only absorbing reactive power; the impedance angle

When , the power state is only active power output; the impedance angle , the power state is only outputting reactive power. In the present invention, the active power P and the reactive power Q are first calculated from the first embodiment, and then the power status is determined according to the sign of the active power P and the reactive power Q and referring to Table 1 in the second embodiment. Power state mainly includes power supply direction, quadrant distribution, impedance angle range, complex impedance properties, active power direction, reactive power direction, and power factor direction. Here, some parameters are defined as follows:

Definition of power supply direction: power consumption is forward (“+”), power supply is reverse (“-”);

的范围为

Definition of power direction: absorption power is positive ("+"), output power is reverse ("-"); impedance angle range definition: impedance angle

in the range of

Definition of power factor λ direction: the range of power factor λ is -1≤λ≤1, wherein, when absorbing active power, it is forward (“+”), and when outputting active power, it is reverse (“-”).

Table 1 Power state four-quadrant distribution table

Claims (1)

1. A four-quadrant power measurement method is characterized in that it is completed by the following steps: start measuring equipment (101); sampling point number N and sampling frequency f _s (102) in a measurement period are set; obtain a measurement period through sampling The voltage sampled value sequence u(n) and the current sampled value sequence i(n)(103) in the voltage sampled value sequence u(n) and the current sampled value sequence i(n) are respectively subjected to discrete Fourier transform to obtain Transformed voltage sequence value U(k) and transformed current sequence value I(k), $\left\{\begin{array}{c}\stackrel{\&Center\; Dot;}{u}\left(k\right)=u_{\mathrm{Rk}}+{\mathrm{jU}}_{\mathrm{Ik}}\\ \stackrel{\&Center\; Dot;}{I}\left(k\right)=I_{\mathrm{Rk}}+i_{\mathrm{Ik}}\end{array}\right.$ (104), where,

is a complex number, respectively representing the kth voltage and current components after the discrete Fourier transform of the voltage and current sampling value sequences u(n) and i(n), U _Rk and U _Ik are the real values of the kth voltage components respectively part and imaginary part, I _Rk , I _Ik are the real part and imaginary part of the kth current component respectively, k=0, 1, 2,..., N-1; according to the transformed voltage sequence value

and the transformed current sequence value

use the formula $\left\{\begin{array}{c}P=u_{R0}{I}_{R0}+\frac{2}{N^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[u_{\mathrm{Rk}}\&Center\; Dot;I_{\mathrm{Rk}}+u_{\mathrm{Ik}}\&CenterDot;I_{\mathrm{Ik}}]\\ Q=\frac{2}{N^2}\underset{k=1}{\overset{N-1}{\mathrm{\&Sigma;}}}[u_{\mathrm{Ik}}\&Center\; Dot;I_{\mathrm{Rk}}-u_{\mathrm{Rk}}\&Center\; Dot;I_{\mathrm{Ik}}]\end{array}\right.$ Calculate active power P and reactive power Q (105); calculate apparent power S and power factor λ (106) according to active power P and reactive power Q; determine power according to the positive and negative signs of active power P and reactive power Q state (107); then return to the initial end of step (103) to complete the power measurement of the next cycle; in step (107), determine the power state of the device under test through the following steps: if active power P is positive, reactive power Q is positive, the quadrant distribution is the I quadrant, the equipment under test is in the state of power consumption, and the corresponding complex impedance is inductive, absorbing active power and absorbing reactive power at the same time, the impedance angle

range is

The value of the power factor λ is positive; if the active power P is negative and the reactive power Q is positive, the quadrant distribution is the second quadrant, the device under test is in the power supply state, and the corresponding complex impedance is capacitive, and the active power is output at the same time Absorbed reactive power, impedance angle

range is

The value of the power factor λ is negative; if the active power P is negative and the reactive power Q is negative, the quadrant distribution is the third quadrant, the device under test is in the power supply state, and the corresponding complex impedance is inductive, and the active power is output at the same time Reactive power, impedance angle

range is

The value of the power factor λ is negative; if the active power P is positive and the reactive power Q is negative, the quadrant distribution is the fourth quadrant, the equipment under test is in the state of power consumption, and the corresponding complex impedance is capacitive, absorbing active power. Simultaneously output reactive power, impedance angle

range is

The value of the power factor λ is positive.

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