CN101398452A - Computation method of dynamic electric energy index of quality based on 100kHz frequency - Google Patents

Abstract

The invention discloses a method for calculating the dynamic power quality index by combing the analysis based on 100 kHz high frequency filtering and time domain waveform, aiming at the characteristic of dynamic voltage fluctuation in power supply of power systems. In the method, the temporary increasing of voltage, voltage sag and short interruption of the dynamic power quality index in the power supply of power systems are calculated by adopting a filtering technology with the 100 kHz constant frequency and a rolling rectangle data window. By adopting the method, the temporal resolution of the dynamic voltage index can reach 10mus. The invention can be used for analyzing the characteristic index of dynamic voltage fluctuation during the operation and faults of the power system and can satisfy various dynamic power quality analysis and application requirements such as operation evaluation of the power system, client voltage allowedness, etc.

Description

Computation method of dynamic electric energy index of quality based on the 100kHz frequency

Technical field

The present invention relates to carry out in a kind of power supply system the dynamic power quality analytical approach in the voltage fluctuation process, particularly relate to a kind of computation method of dynamic electric energy index of quality based on the 100kHz frequency.

Background technology

Development along with automatic production line, accurate control, high-tech enterprise etc., the electricity consumption client has not only proposed also to have proposed the dynamic power quality requirement beyond the higher requirement for the reliability of the distortion of current waveform related in electric system production, the operational process problem, steady state voltage quality problems and energy.

Dynamic power quality refers to that the duration in the several millisecond incident to a few minutes scopes, comprises that voltage dip (sag) and voltage rise (swell) temporarily, and interruption (interruption) in short-term etc.

At present, dynamic power quality also is in conceptual phase, IEC standards such as (International Electrotechnical Commissions) has been discussed definition, algorithm, monitoring requirement of dynamic power quality etc., but, owing to lacking reasons such as detailed Monitoring Data and compatible operational management experience, dynamic power quality does not have concrete controlling index.In developed countries such as the U.S., employer's organizations such as information, electronics are the interests of safeguarding the industry, have proposed the compatible level of dynamic power quality of industry equipment separately, and the equipment that requires industry separately to choose can be allowed the dynamic power quality fluctuation of specialized range.

Be services client better, improve the dynamic power quality level of electric system, Utilities Electric Co. need carry out assay to issuable dynamic electric voltage fluctuation situations such as electric operation, electric network faults, as the foundation of in Electric Power Network Planning, operation, maintenance, technological transformation process, formulating quality of power supply innovative approach, also formulate the foundation that improves the compatible measure of dynamic power quality as the electricity consumption client.

Traditional dynamic voltage quality index test is many with realizations such as whole wave effective value algorithm, half cycles effective value algorithms, and its time resolution is more than the 10ms.And the voltage fluctuation that electric system electric operation, electric network fault produce at a cycle to several cycle in the time period; Obviously its time resolution of existing algorithm can not satisfy the requirement of application.

Analytical approach based on sampled point is arranged in recent years, also have the wavelet analysis method of multiple mode, the prediction that be mainly used in the voltage dip of dynamic voltage compensation purpose, rises or interrupt in short-term temporarily, analysis precision is poor.

Therefore, existing dynamic voltage quality index analysis method can not satisfy the requirement of the characteristic index of voltage dynamic fluctuation in the processes such as assay electric system electric operation, electric network fault, can not satisfy the application requirements that multiple dynamic power quality such as Operation of Electric Systems evaluation and the analysis of user's voltage adaptable degree is analyzed.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of computation method of dynamic electric energy index of quality based on the 100kHz frequency, can be used in the characteristic index of voltage dynamic fluctuation in the processes such as assay electric system electric operation, electric network fault, satisfy the application requirements that multiple dynamic power quality such as Operation of Electric Systems evaluation and the analysis of user's voltage adaptable degree is analyzed.

For addressing the above problem, the computation method of dynamic electric energy index of quality based on the 100kHz frequency of the present invention adopts the rolling rectangular data window, calculates that dynamic electric energy index of quality voltage in the power system power supply rises temporarily, voltage dip and interrupting in short-term; Comprise the steps:

Step 1, utilize the high sample frequency oscillograph of 100kHz record power supply buses voltage to be subjected to change in voltage waveform in electric operation, the electric network fault process;

Step 2, based on equifrequent sampling, adopt 100kHz rolling data window to carry out calculating voltage and rise (famous value), voltage dip (famous value) temporarily by following formula:

$U_{\mathrm{rms}\left(i\right)}=\sqrt{\underset{k=i+1}{\overset{i+N}{\mathrm{\Σ}}}{U}_k^2/N}$ i＝0，1，2……

Wherein, N is ripple sampling number weekly, and N equals 2000; Boundary condition is as follows in computation process: approximate power taking presses the preceding average voltage of fluctuation as the sliding pressure reference value; Voltage fluctuation is ignored for the influence of mains frequency;

Step 3, in the interval of mains frequency scope 49.98Hz～50.02Hz, analyze with 100kHz constant frequency rate sampling, ripple sampled point scope is 1999.2～2000.8 weekly; Under the deviation situation of a sampled point, the effective value error of calculation is:

$\mathrm{\ϵ}={\left(\sqrt{2}{U}_N\right)}^2/U_N^2/2000=0.1\%$

Step 4, carry out voltage with the time interval of neighbouring sample point and roll to calculate, retouch out the voltage per unit value-time changing curve in the voltage fluctuation process, wherein:

Voltage per unit value=voltage rolls and calculates effective value/sliding pressure reference value

The minimum value of voltage per unit value is voltage dip amplitude (per unit value), when this voltage dip amplitude (per unit value) is to interrupt in short-term during less than 0.1p.u, the maximal value of voltage per unit value is the temporary increasing degree value of voltage (per unit value), and the mistiming that surpasses voltage dip or rise threshold value temporarily is the duration.

Adopting method of the present invention, is that the rectangular data window of 2000 sampled points carries out the effective value analysis by constant width, and issuable error is 0.1%, satisfies the requirement of using fully.

And, the dynamic electric voltage index that adopts method of the present invention to calculate, its time resolution reaches 10 μ s, the characteristic index that can be used for process voltage dynamic fluctuation such as assay electric system electric operation, fault fully satisfies various dynamic power quality analytical applications requirements such as Operation of Electric Systems evaluation and the analysis of user's voltage adaptable degree.

Embodiment

The present invention is a kind of at the dynamic electric voltage fluctuating characteristic that relates in the power system power supply, records the computation method of dynamic electric energy index of quality that ripple combines with time-domain waveform analysis based on the 100kHz high frequency.This method is by the record wave technology of 100kHz fixed frequency, adopt the rolling rectangular data window, the dynamic electric energy index of quality voltage that calculates in the power system power supply rises (swell), voltage dip (sag) temporarily and interrupts (interruption) in short-term, is used for carrying out the dynamic power quality analysis of voltage fluctuation process.

Specify methods analyst computation process of the present invention below:

Utilize the high sample frequency oscillograph of 100kHz record power supply buses voltage to be subjected to change in voltage waveform in the processes such as electric operation, electric network fault.

According to international standard [IEC61000-4-30 (2003) Testing and MeasurementTechniques Power Quality Measurement Methods] about dynamic electric energy index of quality voltage rise temporarily, voltage dip and the definition interrupted in short-term, it is as follows that voltage rises/fall temporarily the algorithm of (famous value) temporarily:

$U_{\mathrm{rms}(1/2)}=\sqrt{\underset{k=\frac{j}{2}N+1}{\overset{\frac{j}{2}N+N}{\mathrm{\Σ}}}{U}_k^2/N}$ j＝0，1，2……

Wherein:

N is ripple sampling number weekly;

J carries out the digit that continuous half cycles rolling whole wave effective value calculates;

U _k ²Expression sample amplitude when reproduced value square;

According to the feature that is subjected to factor affecting voltage fluctuations such as electric operation, electric network fault in the power supply process as can be known, voltage fluctuation is often finished in cycle of less than or several cycle, adopt half cycles effective value computing method conventional in the above-mentioned international standard, its time resolution is 10ms, can not describe out the variation characteristic of dynamic voltage quality index.

In order to address this problem, method of the present invention is improved on the basis of above-mentioned international standard definition algorithm, and concrete grammar is: based on the equifrequent sampling, adopt 100kHz rolling data window to carry out calculating voltage and rise temporarily and voltage dip (famous value).That is:

$U_{\mathrm{rms}\left(i\right)}=\sqrt{\underset{k=i+1}{\overset{i+N}{\mathrm{\Σ}}}{U}_k^2/N}$ i＝0，1，2……

Wherein:

N is ripple sampling number weekly.N gets 2000 in the present invention.

Based on to being subjected to the research of factor affecting voltage fluctuation characteristics such as electric operation, electric network fault in the power supply process, boundary condition is as follows in computation process: approximate power taking presses average voltage before the fluctuation as sliding pressure reference value [being used to of IEC61000-4-30 (2003) definition described voltage dip/rise the temporarily term of reference voltage]; Voltage fluctuation can be ignored for the influence of mains frequency.

Under normal circumstances the mains frequency range of control can not exceed the interval of 49.98Hz～50.02Hz.Analyze with the sampling of 100kHz constant frequency rate in this is interval, ripple sampled point scope is 1999.2～2000.8 weekly; Promptly be no more than the deviation of a sampled point.Under the deviation situation of a sampled point, the voltage effective value error of calculation is:

$\mathrm{\ϵ}={\left(\sqrt{2}{U}_N\right)}^2/U_N^2/2000=0.1\%$

Promptly adopt the rectangular data window of 2000 sampled points of constant width to carry out the effective value analysis, issuable error is 0.1%, satisfies the requirement of using fully.

Carry out the voltage rolling with the time interval of neighbouring sample point and calculate the voltage per unit value-time changing curve in the voltage fluctuation process of drawing.Wherein:

Voltage per unit value=voltage rolls and calculates effective value/sliding pressure reference value

According to boundary condition, the sliding pressure reference value is the average voltage (steady state value) before the voltage fluctuation.Thus, can obtain that dynamic electric energy index of quality voltage rises temporarily, voltage dip and the eigenwert of interrupting in short-term: the minimum value of voltage per unit value is voltage dip amplitude (per unit value), when this voltage dip amplitude (per unit value) is to interrupt in short-term during less than 0.1p.u, the maximal value of voltage per unit value is the temporary increasing degree value of voltage (per unit value), and the mistiming that surpasses voltage dip (rising temporarily) threshold value is the duration.(voltage dip/rise threshold value temporarily for judging the threshold value of voltage dip/liter generation temporarily, is represented with per unit value, can also can be provided with according to the needs of research with reference to the recommendation of standards such as IEC).

Claims (1)

1, a kind of computation method of dynamic electric energy index of quality based on the 100kHz frequency is characterized in that: adopt the rolling rectangular data window, calculate that dynamic electric energy index of quality voltage in the power system power supply rises temporarily, voltage dip and interrupting in short-term; Comprise the steps:

Step 1, utilize the high sample frequency oscillograph of 100kHz record power supply buses voltage to be subjected to change in voltage waveform in electric operation, the electric network fault process;

Step 2, based on equifrequent sampling, adopt 100kHz rolling data window to carry out the famous value that calculating voltage rises temporarily, the famous value of voltage dip by following formula:

$U_{\mathrm{rms}\left(i\right)}=\sqrt{\underset{k=i+1}{\overset{i+N}{\mathrm{\Σ}}}{U}_k^2/N}$ i＝0，1，2……

Wherein, N is ripple sampling number weekly, and N equals 2000; Boundary condition is as follows in computation process: approximate power taking presses the preceding average voltage of fluctuation as the sliding pressure reference value; Voltage fluctuation is ignored for the influence of mains frequency;

Step 3, in the interval of mains frequency scope 49.98Hz～50.02Hz, analyze with 100kHz constant frequency rate sampling, ripple sampled point scope is 1999.2～2000.8 weekly; Under the deviation situation of a sampled point, the effective value error of calculation is:

$\mathrm{\ϵ}={\left(\sqrt{2}{U}_N\right)}^2/U_N^2/2000=0.1\%$

Step 4, carry out voltage with the time interval of neighbouring sample point and roll to calculate, the voltage per unit value-time changing curve in the voltage fluctuation process of drawing, wherein:

Voltage per unit value=voltage rolls and calculates effective value/sliding pressure reference value

The minimum value of voltage per unit value is the per unit value of voltage dip amplitude, when the per unit value of this voltage dip amplitude is to interrupt in short-term during less than 0.1p.u, the maximal value of voltage per unit value is the per unit value of the temporary increasing degree value of voltage, and the mistiming that surpasses voltage dip or rise threshold value temporarily is the duration.