谐波检测方法-中英文

线调频小波变换满足上述要求，

使用的时频分析窗口除了时移、

频移、

尺度

变化以外，

最主要的是包含了时频窗口在时频平面上的放置以及在倾斜方向上的

尺度变化

拉伸

)

。

由于使用各种长方形和各种平行四边形的时频窗口，

所以线调

频小波变换可以分析具有非固定不变带宽和非固定比例带宽

(

< br>非恒

Q)

的突变信

号。

信号的消噪、滤除干扰、压缩、恢复以及故障信号检测、诊断、识别、 定位

是电力系统信号处理的主要工作，

其目的是尽可能地复原被 噪声或干扰污染的信

息源以及故障的特征和类型。

严格地讲，< /p>

干扰和噪声是两个不同的概念。

干扰指

周 期的、有规律的误差信号

(

测量信号与真实信号的差

；而理论上不能预测的、

必须用概率统计刻画划 的误差信号定义为噪声。

电力系统在采样信号时，

现场存

在大量噪声和干扰信号，

严重影响了系统、

设 备监测的灵敏度和可靠性，

因此消

除干扰和滤掉噪声是电力设备 监测的一个关键技术问题。

在电力 系统中，

快速傅立叶

(FFT)

阈值滤 波法和最小均方误差

(LMS)

自适应滤

波器是最常用的用来抑制干扰和消噪方法。但是，

FFT

阈值 滤波不能消除平稳随

机型干扰，

而

LM S

自适应滤波器收敛性能受时延、

收敛因子等参数的影响，

滤波

效果不稳定，甚至有时不收敛。基于小波变换的干扰滤波器研究 不多，文［

7

］

在干扰滤波方面作了尝 试，

它将干扰信号分为脉冲型干扰、

连续周期型干扰和平

稳随机型干扰。

主要讨论连续周期型和平稳随机型干扰信号的抑制。< /p>

仔细分析后，

文中对平稳随机型干扰即白噪声进行了基于小波变换 的分析处理，

对有色噪声未

涉及。

对连 续周期型干扰滤波论及不多，

小波变换对这类干扰应该也不是有效的。

< br>文

［

10

］

论及到连续周期型干扰滤波问题，

它提出了

3

次

B

样条小波对采样信号

进 行预处理的方法，可基本消除偶次谐波和

1.5

次以上非整数次 谐波。

The method of The Harmonics examination

The Harmonics examination is Harmonics an important branch within

problem.

which

has

an

important

instruction

function

to

repress

Harmonics.

Is

a

power

system

analysis

and

control

a

key

job

to

the

harmonic

analysis

and the diagraph. Is also to after electricity protection, judgment the

breakdown

order

and

break

down

a

type

etc.

work

of

important

premise.

Now

how to accurate, quickly examine the distortion current, voltage is the

target that numerous domestic and international scholars concentrate on

a research. The Harmonics of normal measures method mainly have three

methods:

The

Harmonics

of

measure

according

to

the

analogous

filter;

The

Harmonics of measure according to Fourier transform; The Harmonics of

measure according to the instantaneous reactive power.

First

、

(The analogous filter) the earliest Harmonics examination's

method.

The Input

signal

sends into

a

set of

band pass filter after

amplify.

The center frequency of filter f1

、

f2

、…

fn is fixed. Which is for the

integral

of

run

frequency

doubly.

f1

〈

f2

…

〈

fn.

Then

send

many

manifestation in and value. This method carries out electric circuit in

brief, building pr the road displays diagraph signal composition in the

Harmonics contained ice low, output resistance is article prime

factor is easy to a control. But the circuit is more difficult design,

the error margin is big, to motion and circuit component of the charged

barbed

wire

net

frequency

parameter

very

sensitive,

Make

to

there

is

more

base

frequency

in

the

Harmonics

of

examining

weight,

circulate

to

exhaust

greatly.

Second

、

FFT(Fast Fourier transform)

Along

with

the

technical

development

of

the

calculator

and

the

micro- electronics,

Start

to

adopting

the

method

that

the

Fourier

analysis

to

examine

Harmonics

and

reactive

current.

This

kind

of

method

according

to collect of an electric current value of power supply period carry on

a calculation. Finally get the Harmonics needed by reactive current. It

can analyze by the square time with examination integral Harmonics. But

because

the

Fourier

transform

carries

on

two

transformation.

The

calculation has great capacity, computing time is long, So examination

time also is longer.

Third

、

(Instantaneous reactive power)

The

Japanese

scholar

puts

forward

in

1983

of

the

moment

has

Instantaneous reactive power theories. Then the

ｐ－ｑ

theories solves

Harmonics and reactive power of the moment examine with need not keep

ability the component can carry out to repress Harmonics and reactive

power

compensation

etc.

problem.

The

theories

research

which

makes

active

filter

the

theories

from

the

laboratory

thus

heads

for

a

work

application.

According

to

this

theories.

We

can

get

to

have

a

instantaneous

active

power