WO2014063634A1

WO2014063634A1 - Processing method and device for digital measurement or telemetry of electric power system

Info

Publication number: WO2014063634A1
Application number: PCT/CN2013/085807
Authority: WO
Inventors: 郝玉山
Original assignee: Hao Yushan
Priority date: 2012-10-23
Filing date: 2013-10-23
Publication date: 2014-05-01
Also published as: CN102928014A; CN102928014B

Abstract

The present invention relates to a steady-state processing method and device for digital measurement or telemetry of an electric power system, including: inputting a data sequence {y_k} = {y_k, y_k-1,... y_k-N} of the digital measurement or telemetry of a physical quantity y; according to the data sequence {y_k}, calculating the n+1 order derivative of y, n = 0, 1,..., until a formula (I) is satisfied, so as to determine n; performing variable substitution with a formula (II), and calculating a data sequence {x_k}; judging that a current numerical value x_k is located in a transient-state process or a steady-state process; when the current numerical value x_k is judged to be located in the steady-state process, calculating an average value as a steady-state value according to {x_k}; and performing integral inverse transformation, and solving the steady-state value of y from. Also proposed is another steady-state processing method and device for digital measurement or telemetry of an electric power system by adopting a Kalman filter to substitute for the above derivation process. The present invention is applicable to two conditions of the field of digital measurement or telemetry, and performs accurate steady-state processing in the whole process of determining the physical quantity of an electric power system.

Description

Method and device for digital measurement or telemetry processing of power system

The present invention relates to digital measurement or telemetry data processing techniques, and more particularly to digital measurement or telemetry data steady state processing techniques for voltage, power, phase angle, etc. in a power system. Background technique

The actual power system operates in the process of steady state, transient, steady state, ... alternating, the steady state process refers to the process that the value of the physical quantity remains basically unchanged or does not change for a long period of time, two steady state processes The transition between them is called a transient process.

The analog-to-digital conversion process for physical quantities is called digital measurement. Most of the actual systems only care about the steady-state value. In this case, the digital measurement data needs to be processed in a steady state; the data obtained by the local digital measurement is sent to the remote computer through communication ( Called the primary station, it is called telemetry. The data received by the primary station is telemetry data. Most of the actual telemetry systems only care about the steady-state value. The main station needs to perform steady-state processing on the telemetry data.

In the patent 200910158370 "Physical Data Acquisition Method and Apparatus", a method for steady-state measurement of physical quantities is proposed, but only the steady-state process is processed. The transient process is considered to be short and ignored, which may make A large amount of data is discarded, resulting in a long-term transient process that cannot handle steady-state values, and the telemetry data also includes information such as time stamps, which does not apply to upgrades of existing automation systems. Summary of the invention

In order to solve the above technical problem, the present invention proposes a steady state processing method for digital measurement or telemetry of a power system, which comprises the following steps:

Sl, the data sequence of the digital measurement or telemetry of the input physical quantity y {^ μ ^ , }^ , · · · , ^^ } , where k is the current sampling point number and N is the time window width;

S2, calculating the n+1 derivative of y according to the data sequence {yj, η=0,1,... until d _ y is satisfied

< ε dt ^n+l Thereby determining n, where ε is a constant close to zero;

53. Do variable substitution c = ^, calculate the data sequence from the data sequence { _y J

Dt ⁿ

54. For the data sequence { : , judge whether the current value is in a transient process or a steady state process;

55. When it is determined that the current value is in a steady state process, the average value is calculated according to { } as the steady state value 3⁄4, and step S6 is performed; when it is determined that the current value is in the transient state, let k=l;

56. Perform an inverse inverse transformation on the steady-state value of x to calculate the steady-state value of y;

57. Output steady state value.

For the physical quantity y, the mathematical description of the transient process is the ordinary differential equation of time. The solution of the ordinary differential equation includes the free component y _t (t) and the forced component y _s (t), ie

y(t) = y _t (t) + y _s (t)

The free component y _t (t) is the attenuation component associated with the initial value. The free component tends to zero over time, ie y _t (t) _{t → ∞} ) 0; the forced component y _s (t) is related to the input. , a steady-state solution that does not decay. In engineering applications, it is considered that t>3i: after, y _t (t) is 0, where τ is the time constant of the system; digital measurement, especially the sampling time of telemetry is often greater than 3τ, so in the transient process, y(t) The sampled value) ^ has only the forced component ^ (3⁄4.

In power automation, the interval between digital measurement or telemetry data is greater than 3τ, and the forced component of the voltage, current rms, and active and reactive power are only forced components. The load-shedding curve of the prefecture-level dispatching and county-level dispatching is stepped, while the daily load curve of the above-mentioned provincial dispatching is braided. In the former, the first derivative of power is close to 0, that is, η = 0; in the latter, the second derivative of power is close to 0, that is, η = 1. That is to say, the forced component of the power telemetry data either has a first derivative close to 0 or a second derivative close to 0. In general, η does not exceed 3, and the η+1 derivative is close to zero.

From the perspective of motion physics, the uniform motion ^ = 0, that is, the η = 1, the force balance is a steady state process, dr

v=constant, s = + _v . , v and s are easy to measure; uniform acceleration motion ^ f = o, ie the n = 2, do dt

In tube physics, it is considered that the uniform acceleration motion is not a steady state process, but _β = ^ = constant, and easy to measure, dt

After that, _v = _Vo +fl^ and = + _ν(Γ + 1/2·β· ² are also easy to obtain; mathematically, if ^ ^ = 0, then ^ is a constant, easy to measure, after measuring ^ is accurate, very It is easy to integrate ^, , ..., dt ⁿ dt ⁿ dt ⁿ dt ⁿ until y is obtained.

Using this knowledge, the present invention proposes a steady state process for digital measurement or telemetry of the above power system. Method, from SI to S7, the steady state value calculation of the physical quantity of electricity is completed in seven steps.

The step S2 calculates the derivatives according to the data sequence { _y J. In mathematics, there are many methods for obtaining the first derivative and the high derivative by numerical values, such as forward difference, backward difference, center difference, etc. Let me repeat.

In step S4, it is determined whether the current value is in a steady state process or a transient process. If X is in a steady state process, its value is a constant value. Due to the influence of random interference, it conforms to the characteristics of stationary random variables in statistical mathematics, then Obey the t distribution; otherwise, if it does not obey the t distribution, it does not belong to the stationary random variable, that is, it does not belong to the steady state process. Specifically:

The step S4 determines whether the current value is in a transient process or a steady state process according to the t distribution.

1, if t ^ obeys distribution 0, if fe^J does not obey ₍ W distribution

When F=l, it is in the steady state process; when F=0, it is in the transient process; where, it is the average value, 3⁄4 is the standard deviation, and t(k) is the t distribution with the degree of freedom k.

The above criteria for judging whether the current value is in a transient process or a steady state process can be summarized as:

Ίι, if | — | ≤ G-4

F = , _m

[0, if | - |> G- where, is the average, 3⁄4 is the standard deviation, and G is the given constant. The G is located between 2.5 and 15.

The above criteria can be further reduced to: x _e

Where is the average value, δ is a given constant, and _Xe is the nominal value of the physical quantity X. The δ is at 0.1% ~

Between 10%.

The average and standard deviation 3⁄4 calculations can be performed as follows:

When F = l changes F = 0, that is, when the current value enters the transient process from the steady state process, let k = l;

= -j ~~ 73⁄4-i +(3⁄4 ~3⁄4-i) ^{2 +} -j ~~ r(3⁄4 _ )2 , k = k+l.

—1 —1

In the step S5, the average value is calculated with reference to the above method, and the description will not be repeated here. In the step S6, the inverse state of the steady state value of x is inversely transformed. Since the steady state value is approximately constant, y _k . x _k , <3⁄4, (3⁄4, (3⁄4,···, α _η _ _χ is press

The constant determined by the derivative formula and the initial value of the physical quantity y and its derivatives. The Kalman filter can filter out the output state variables, ie the first derivative, the second derivative of y, the ..., n+1 derivative, and thus, the derivatives of the above-mentioned steady-state processing methods for digital measurement or telemetry of power systems It can also be obtained by a Kalman filter.

Thus, the present invention also proposes another steady state processing method for digital measurement or telemetry of a power system, which comprises the following steps:

Pl, the digital measurement of the physical quantity y or the data sequence of the telemetry {^μ^,}^,···, ^^}, where k is the current sampling point number and N is the time window width;

P2, according to the data sequence {>3⁄4}, using the Kalman filter to obtain the derivative of the physical quantity y, and determining that the absolute values of the derivatives of the order n+1 and above are smaller than the minimum order η of ε, wherein η = 0, 1, 2, 3, ε is a constant close to 0;

Ρ3. When η is the same as the η value judged by the previous sampling point, judge that the η-order derivative of y is in a steady state process, and proceed to step Ρ4; otherwise, let k=l;

P4. When it is determined that the nth derivative of y is in a steady state process, the steady state value of y is calculated from the nth derivative of y;

P5, output steady state value.

The step P4 is according to the formula = ₀ . + ₀ + ^ + ₀₃ ^+~+ ₀ „^" calculates the steady-state value of y, where _l is in accordance with the derivative formula and y and its derivatives

The constant determined by the initial value. Correspondingly, the present invention provides a steady state processing apparatus for digital measurement or telemetry of a power system, which includes:

Input unit, for inputting a digital measurement or telemetry data sequence of physical quantity y ^ ^,)^,...,)^^, where k is the current sampling point number and N is the time window width;

Deriving unit, configured to calculate n+1 derivative of y according to the data sequence {yj, η=0,1,..., until Thereby determining n, where ε is a constant close to zero;

a replacement unit for variable replacement c judgment unit for receiving a data sequence "[ }, determining whether the current value is in a transient process or a steady state process;

a calculation unit, configured to determine that the current value is in a steady state process, calculate an average value as a steady state value according to { }; and determine that the current value is in a transient process, let k=l;

The reducing unit is configured to perform an inverse inverse transformation on the steady state value of X when determining that the current value is in a steady state process, and calculate a steady state value of y;

Output unit for outputting steady state values.

The determining unit determines whether the current value is in a transient process or a steady state process according to the t distribution:

1, if ^ ^ obeys distribution 0, if fe^J does not obey ₍ W distribution

The above criteria can be summarized as:

If | - | ≤ G-4

If | — |> G- where, is the mean, 3⁄4 is the standard deviation, and G is the given constant. The G is located between 2.5 and 15.

for:

Where is the average value, δ is a given constant, and _Xe is the nominal value of the physical quantity X. The δ is between 0.1% and 10%.

The average and standard deviation 3⁄4 can be calculated as follows:

When F=l becomes F=0, that is, when the current value enters the transient process from the steady state process, let k=l;

When fc≥2: x _k = -((kl)-x _k _ _l +x _k ) , _{= ~ Ί ~~ 7¾-i +} (¾ ~ ¾-i) 2 ~~ r (¾ _) 2, k = k + l.

c -1 c -1

The calculation unit calculates an average value by referring to the above method, and the description will not be repeated here.

The reducing unit performs an inverse inverse transformation on the steady state value of X. Since the steady state value is approximately constant, y _k = a _Q + a _{x -} t + a _{2 -} t ² + a - t - Ya _n - f ·> where a _n =- . x _k , <3⁄4,(3⁄4,(3⁄4,···, a _n _ _x is by n

The constant determined by the derivative formula and the initial value of the physical quantity y and its derivatives. Correspondingly, the present invention also proposes another steady state processing device for digital measurement or telemetry of a power system, which includes:

a filtering unit, configured to filter out each derivative of the physical quantity y by using a Kalman filter according to the data sequence {yj, and determine that the absolute value of the derivative of the n+1 order and the above order is smaller than the minimum order n of ε, wherein, n =0, 1, 2, 3, ε is a constant close to 0;

a determining unit, configured to: when η is the same as the value of η determined by the previous sampling point, determine that the n-th derivative of y is in a steady state process, and enter the calculating unit; otherwise, let k=l;

a calculation unit, configured to calculate a steady-state value of y from the n-th derivative of y when determining that the n-th derivative of y is in a steady state process;

Output unit for outputting steady state values.

The calculation unit, according to = _α . + _αι · + · ² + _α3 · ³ +~ + _α „ · " Calculate the steady-state value of y, where is the first n dt ⁿ according to the derivative formula and y and its derivatives

The constant determined by the value.

The invention provides two methods and devices for digital measurement or telemetry processing of a power system, which are suitable for both on-site digital measurement and main station telemetry processing, and calculate a steady state value for the whole process of the physical quantity of the power system, thereby improving data measurement and The accuracy of telemetry data.

DRAWINGS

1 is a schematic diagram of a steady state processing method for digital measurement or telemetry of a power system according to the present invention.

2 is a schematic diagram of another steady state processing method for digital measurement or telemetry of a power system according to the present invention. 3 is a schematic diagram of a steady state processing device for digital measurement or telemetry of a power system according to the present invention.

4 is a schematic diagram of another steady state processing device for digital measurement or telemetry of a power system according to the present invention. detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used for the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

FIG. 1 is a schematic diagram of steps of a method for digitally measuring or telemetry steady state processing of a power system according to an embodiment of the present invention. As shown in the figure, the method includes the following steps:

Sl, input the digital measurement of the physical quantity y or the data sequence of the telemetry {^μ^,}^,···, ^^}, where k is the current sampling point number, and N is the time window width;

52, according to the data sequence d y

{yj calculates the n+l derivative of y, η=0,1,... until n+l < ε , dt is satisfied to determine n, where ε is a constant close to 0;

d

55. When it is determined that the current value is in the steady state process, the average value is calculated as {stead value 3⁄4 according to { }, and step S6 is performed; when it is determined that the current value is in the transient state, let k=l;

57. Output steady state value.

Step S4, determining whether the current value is in a transient process or a steady state process according to the t distribution, obeying the distribution

F =

0, if ^^ disobeys distribution

When F = l, it is in the steady state process; when F = 0, it is in the transient process; where, is the average value, 3⁄4 is the standard deviation, and t(k) is the t distribution with a degree of freedom of k.

In the step S5, the average value is calculated with reference to the above method, and the description will not be repeated here.

The constant determined by the derivative formula and the initial value of the physical quantity y and its derivatives. 2 is a schematic diagram showing the steps of a steady state processing method for digital measurement or telemetry of another power system according to the present invention. As shown, it includes the following steps:

P2. According to the data sequence { _y J, using the Kalman filter of 4th order and below, the derivative of the physical quantity y is obtained, and the absolute order of the derivatives of the order n+1 and above is determined to be smaller than the minimum order of ε. n, where η = 0, 1, 2, 3, ε is a constant close to 0;

P5, output steady state value.

Where, in step P4, when the nth derivative of y is in a steady state process, the nth derivative of y is an approximate constant, which is approximated as a constant C, and then = _α . + _αι · + · ² + α ₃ · ³ +~ + _α „· " Calculate the steady-state value of y, where , ^,...,^^ is in accordance with the derivative formula and y and its various orders

The initial value of the number is determined by a constant. 3 is a schematic diagram of a power system digital measurement or telemetry steady state processing device according to the present invention, as shown in the figure, which includes:

Input unit 1, a data sequence for inputting a digital measurement or telemetry of physical quantity y ^ ^,)^,...,)^^, where k is the current sampling point number and N is the time window width;

Deriving unit 2, configured to calculate n+1 derivative of _y according to the data sequence { _y J, η=0,1,..., until Meet dy

n + l ≤ ε, thereby determining n, where ε is a constant close to 0;

Dt

Substitute unit 3, which is used for variable substitution c = 2, and the data sequence { _y J calculates the data sequence dt ⁿ judgment unit 4 for receiving the data sequence " [ }, and judges whether the current value is in a transient process or a steady state process;

The calculating unit 5 is configured to determine that the current value is in a steady state process, and calculate an average value as a steady state value according to { }; when determining that the current value is in a transient state, let k=l;

The restoration unit 6 is configured to perform inverse integration on the steady state value of X when determining that the current value is in a steady state process, and calculate a steady state value of y;

Output unit 7 is used to output the steady state value.

The determining unit 4 determines whether the current value is in a transient process or a steady state according to the t distribution:

Obey

F =

0, if ^^ disobeys distribution

When F=l, it is in the steady state process; when F=0, it is in the transient process; where, it is the average value,

3⁄4 is the standard deviation, and t(k) is the t distribution with a degree of freedom of k.

Ίι, if | — | ≤ G-4

F = , _m

The above criteria can be further reduced to:

= |i if |

[0 if \x _k

x _e

Where is the average value, δ is a given constant, and _Xe is the nominal value of the physical quantity X. The δ is located

Between 0.1% and 10%.

When F=l becomes F=0, that is, when the current value enters the transient process from the steady state process, let k=l; k=lH: =·3⁄4, 3⁄4 ² = 0 , k = k+l;

k≥2H: x _k = -((kl)-x _k _ _l +x _k ) ,

K

= -j ~~ 73⁄4-i +(3⁄4 ~3⁄4-i) ^{2 +} -j ~~ r(3⁄4 _ )2 , k = k+l.

K-1 K-1

The calculating unit 5 calculates an average value by referring to the above method, and the description will not be repeated here.

The reducing unit 6 performs an integral inverse transformation on the steady state value of X. Since the steady state value is approximately constant, y _k = a _Q + a _x -t + a ₂ -t ² + a -t - Ya _n -f ·> where a _n =— . x _k , a _n _ _x is a constant determined according to the derivative formula and the initial value of the physical quantity y and its derivatives. 4 is a schematic diagram of another steady state processing apparatus for digital measurement or telemetry of a power system according to the present invention. As shown, it includes:

Input unit A, a data sequence for inputting a physical quantity y or a telemetry data ^ ^,)^,...,)^^, where k is the current sampling point number and N is the time window width;

The filtering unit B is configured to filter out the derivatives of the physical quantity y according to the data sequence {yj using the Kalman filter of the fourth order and below, and determine that the absolute value of the derivative of the n+1 order and the above order is smaller than ε a minimum order η, where η = 0, 1, 2, 3, ε is a constant close to 0;

The determining unit C is configured to: when η is the same as the value of η determined by the previous sampling point, determine that the η-order derivative of y is in a steady state process, and enter the calculating unit Ε; otherwise, let k=l;

The calculation unit D is used to determine the steady state value of y from the nth derivative of y when determining that the nth derivative of y is in a steady state process;

Output unit E, for output steady state value.

The calculation unit D, the process of calculating the steady state value of y from the nth derivative of y is to approximate the nth derivative of y to a constant C, and then according to = ₀ . + ₀ + ^ + ₀₃ ^+~+ ₀ „^” calculates the steady-state value of y, where a _n =丄-C, Α,^,-,α^ is in accordance with the derivative formula and y and its order n !

The constant determined by the initial value of the derivative.

The invention provides two methods and devices for digital measurement or telemetry processing of a power system, which are suitable for two situations of on-site digital measurement and main station telemetry, and calculate steady state values for the whole process of the physical quantity of the power system, and improve data measurement and telemetry. The accuracy of the data.

The structure, features and effects of the present invention are described in detail above based on the embodiments shown in the drawings. The above are only the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments shown in the drawings, and the modifications made in accordance with the concept of the present invention, or modified equivalents to equivalent changes, are not exceeded. The spirit of the specification and the illustrations are intended to be within the scope of the invention.

Claims

A steady state processing method for digital measurement or telemetry of a power system, comprising the steps of:

, d y

52. Calculate n + l derivative y of y according to the data sequence {yj η = 0, 1, ... until n + l < ε , dt is satisfied to determine n, where ε is a constant close to 0;

d

57. Output steady state value.

2. The steady state processing method for digital measurement or telemetry of a power system according to claim 1, wherein:

In the step S4, the criterion for judging whether the current value is in a transient process or a steady state process is obeying the distribution.

F =

0, if fe^J does not obey ₍ W distribution

3. The method of claim 1, wherein the criterion is:

Il, if | — | ≤ G-4

F = , _m

[0, if | - |> G- where, is the average, 3⁄4 is the standard deviation, and G is the given constant.

4. The method of claim 2, wherein the criterion is summarized as: ₌ |i if |

0 if \x _k

x _e

Where is the average value, δ is a given constant, and _Xe is the nominal value of the physical quantity χ.

5. The steady state processing method for digital measurement or telemetry of a power system according to claim 1, wherein:

The step S6 is according to the formula = ₀ . + ₀ + ^ + ₀₃ ^+~+ ₀ „^” calculates the steady-state value y _{k of} y , where is the constant determined by the derivative formula and the initial value of y and its derivatives.

6. A steady state processing method for digital measurement or telemetry of a power system, comprising the steps of:

P2. According to the data sequence { _y J, the Kalman filter is used to filter out the derivatives of the physical quantity y, and it is determined that the absolute values of the derivatives of the n+1 order and the above are smaller than the minimum order n of ε, where n= 0,l,2,3, ε is a constant close to 0;

P5, output steady state value.

7. The steady state processing method for digital measurement or telemetry of a power system according to claim 6, wherein:

The step P4 is according to the formula = ₀ . + ₀ + ^ + ₀₃ ^+~+ ₀ „^” calculates the steady-state value of y, where _βQ , _βl , _β2 ,..., _{1 are} in accordance with the derivative formula and y and its derivatives.

The constant determined by the value.

8. A steady-state processing device for digital measurement or telemetry of a power system, comprising: an input unit, a data sequence for inputting a digital measurement or telemetry of a physical quantity y ^^,)^,...,)^^, wherein k is the current sampling point number, and N is the time window width;

Output unit for outputting steady state values.

9. The steady state processing apparatus for digital measurement or telemetry of a power system according to claim 8, wherein: the criterion of the determining unit is:

1, if t ^ obeying distribution

0, if fe^J does not obey ₍ W distribution

10. The steady state processing apparatus for digital measurement or telemetry of a power system according to claim 9, wherein: said criterion is:

Il, if | — | ≤ G-4

F = , _m

11. The steady state processing apparatus for digital measurement or telemetry of a power system according to claim 9, wherein

Where is the average value, δ is a given constant, and _Xe is the nominal value of the physical quantity X.

12. The steady state processing apparatus for digital measurement or telemetry of a power system according to claim 8, wherein: said reducing unit calculates y according to a formula ^+^ + ^^ + ^^+...+ ^^" Steady-state value, where, is in accordance with the derivative formula and y and its derivatives The initial value is determined by a constant.

13. A steady-state processing device for digital measurement or telemetry of a power system, comprising: an input unit for inputting a digital measurement of a physical quantity y or a data sequence of telemetry

^ ^,)^,...,)^^, where k is the current sampling point number and N is the time window width;

a filtering unit, configured to filter out each derivative of the physical quantity y by using a Kalman filter according to the data sequence {>3⁄4}, and determine that the absolute value of the derivative of the n+1 order and the above order is smaller than the minimum order n of ε, wherein , n=0, 1, 2, 3, ε is a constant close to 0;

Output unit for outputting steady state values.

14. The steady state processing apparatus for digital measurement or telemetry of a power system according to claim 13, wherein: said calculating unit is according to the formula = ₀ . + ₀ + ^ + ₀₃ ^+... + ₀ „^” calculated steady-state values, where _l is in accordance with the derivative formula and y and its various derivatives

The initial value of the number is determined by a constant.