CN111314006A - A Time-Delay Curve Fitting Method Based on Data Transmission Without Time-Scale Out-of-limit Data - Google Patents

Abstract

A time delay curve fitting method based on time-mark-free out-of-limit data transmission is characterized in that dynamic delay is determined by an IEEE1588 synchronization protocol, scatter point distribution is formed according to coordinate points of deviation delta t of a master clock and a slave clock, active load scatter point distribution of synchronization of the slave clock of a transformer substation and the master clock of a power generation station is calculated according to active load scatter point distribution conditions transmitted between the transformer substation and the power generation station, synchronization precision meets requirements, and then an active load curve is obtained through curve fitting. The advantages are that: and the data synchronization reliability of the power plant and the transformer substation is improved, so that the availability of the power plant to the power station data is ensured, and the reliable operation of the intelligent power grid is guaranteed.

Description

A Time-Delay Curve Fitting Method Based on Data Transmission Without Time-Scale Out-of-limit Data

technical field

The invention relates to a time-delay curve fitting method based on data transmission without time-scale overrun, in particular to a time-delay curve fitting between power plants and substations and between substations and substations based on time-scale overrun data transmission method.

Background technique

With the development and wide application of computer technology, cloud computing technology and big data analysis technology, more advanced applications based on power grid big data have proposed more advanced applications for the synchronization and synchronization stability of data between power plants and substations, as well as between substations. high demands.

However, due to the lack of comprehensive consideration of the total station time synchronization system in the initial stage of the construction of the substation, there are multiple time synchronization systems in the substation at the same time, and multiple clock sources complete the time synchronization of the equipment in the station. As a result, the time synchronization precision of different devices in the station is different, and the message time stamp is also different, which reduces the availability of the data sent by the dispatcher to each substation. Therefore, how to improve the reliability of data synchronization between power plants and substations has become a key link in the reliability of substation data.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a time-delay curve fitting method based on data transmission without time scale overrun to improve the synchronization reliability of power plant and substation data to ensure the availability of power station data from the substation.

The technical scheme of the present invention is:

A time-delay curve fitting method based on data transmission without time-scale and out-of-limit data, characterized in that:

Specific steps are as follows:

Step 1: IEEE1588 synchronization protocol to determine dynamic delay curve

The clock of the power plant is the master clock of the master station, and the clock of the substation is the slave clock of the factory station.

t1+Delay=t2+Offset (1)

t4=t3+Offset+Delay (2)

Among them, t1 represents the time when the master clock of the master station sends out the command, and t2 represents the time when the factory station receives the command command issued by t1 from the clock. ;

t3 represents the time when the factory station sends the command from the clock, t4 represents the time when the master clock of the master station receives the command from t3;

Delay represents the network delay of packet transmission, and Offset represents the deviation between the master clock and the slave clock;

From formula (1) and formula (2), we can get:

Delay=(t2-t1)+(t4-t3)/2 (3)

Offset=(t4-t3)-(t2-t1)/2 (4)

The deviation Offset between the slave clock and the master clock is obtained, which is recorded as Δt. At different times, the coordinate points of the master clock and the slave clock deviation Δt form a scatter distribution;

Step 2 Synchronize Active Loads

According to the scatter distribution of the coordinate points of the deviation Δt between the master clock and the slave clock, the scatter point distribution of the active load transmitted between the substation and the power plant is calculated to calculate the scatter point distribution of the active load synchronous between the slave clock of the substation and the master clock of the power station, Then the active load curve is obtained by curve fitting;

Step 3 Curve Fitting

Assuming given data points (x _i , y _i ) (i=0, 1, . . . , m), x _i represents time t, and y _i represents active load P;

According to the given m points, the curve is not required to pass through these points exactly, but the approximate curve y=p(x) of the curve y=f(x);

使得近似曲线p(x)在点i处的偏差I最小，即find approximate curve

Make the deviation I of the approximate curve p(x) at the point i the smallest, that is

which is

Obtain the multivariate functions of a ₀ , a ₁ ,...an in equation (7), obtain the _extreme value of I=I(a ₀ , a ₁ ,...an ₎ , and obtain the least squares polynomial fitting The resultant curve is the active load fitting curve.

Beneficial effects of the present invention:

According to the scatter distribution of the coordinate points of the deviation Δt between the master clock and the slave clock, the scatter point distribution of the active load transmitted between the substation and the power plant is calculated to calculate the scatter point distribution of the active load synchronous between the slave clock of the substation and the master clock of the power station, The synchronization accuracy meets the requirements, and then the active load curve is obtained by curve fitting to improve the synchronization reliability of the power plant and substation data, to ensure the availability of the substation data to the power station, and to provide a guarantee for the reliable operation of the smart grid.

Description of drawings

FIG. 1 is a scatter diagram of clock deviation Δt of station A according to an embodiment of the present invention;

The clock deviation Δt scatter distribution diagram of station B in Fig. 2;

Fig. 3 is the scatter point distribution diagram of active load of station A according to the embodiment of the present invention;

Fig. 4 is the active load scatter point distribution diagram of station B according to the embodiment of the present invention;

Fig. 5 is a scatter diagram of active load after station A is moved forward by Δt in Fig. 3;

Fig. 6 is a scatter diagram of active load after station B in Fig. 4 is moved forward by Δt;

Fig. 7 is a graph of active load obtained after fitting the scatter point distribution of active load in Fig. 5;

FIG. 8 is a graph of the active load obtained after fitting the scatter point distribution of the active load in FIG. 6 .

Detailed ways

Example

It is assumed that a power station (station A) and a 220kV substation (station B) are included in a certain area. It is assumed that there is one main transformer in the power station and substation, and one 220kV outlet. In order to ensure the independence of the two stations, each station is equipped with an independent interval switch, and at the same time meets the requirements of the dual redundant design of the system. The 220kV line interval realizes the 220kV line protection and measurement and control functions through a merging unit and an intelligent unit. The 220kV bus tie interval collects the digital quantity and state quantity of the interval and the bus PT interval to realize the 220kV bus tie protection measurement and control function, and the bus difference protection IED Collect information across intervals to realize 220kV bus differential protection function. The collection of active load and Δt between station A and station B is shown in Table 1, where the clock deviation Δt is calculated as follows:

Delay=(t2-t1)+(t4-t3)/2 (1)

offset=(t4-t3)-(t2-t1)/2 (2)

t1 represents the time when the master clock of the master station sends an instruction, and t2 represents the time when the factory station receives the instruction command issued by t1 from the clock. ;

t3 represents the time when the factory station sends the command from the clock, t4 represents the time when the master clock of the master station receives the command from t3;

The deviation Offset between the slave clock and the master clock is obtained, which is recorded as Δt. At different times, the coordinate points of the master clock and the slave clock deviation Δt form a scatter distribution, as shown in Figure 1 and Figure 2 (the abscissa is t, the unit is t). :s);

Table 1 Collection table of active load and Δt (unit: μs)

According to the coordinate points of the master clock and the slave clock deviation Δt, the scatter distribution is formed, and the active load transmission between the substation and the power plant is scattered (as shown in Figure 3 and Figure 4 (the abscissa is t, unit: s)), Calculate the active load scatter point distribution of the substation slave clock synchronized with the power station master clock (as shown in Figure 5 and Figure 6 (the abscissa is t, unit: s)), and then obtain the active load curve by curve fitting;

The specific steps of curve fitting are as follows:

Assuming given data points (x _i , y _i ) (i=0, 1, . . . , m), x _i represents time t, and y _i represents active load P;

According to the given m points, the curve is not required to pass through these points exactly, but the approximate curve y=p(x) of the curve y=f(x);

使得近似曲线p(x)在点i处的偏差I最小，即find approximate curve

Make the deviation I of the approximate curve p(x) at the point i the smallest, that is

which is

Obtain the multivariate functions of a ₀ , a ₁ , ...an in formula (4), and obtain the extreme value of I=I(a ₀ , a ₁ , ... _{an )} ;

In order to find the value of a that meets the conditions, find the partial derivative of a _i on the right side of the equation; it is a system of linear equations about a ₀ , a ₁ , ... a _n , which is represented by a matrix as:

最小二乘法多项式拟合曲线，即有功负荷拟合曲线，如图7和图8所示(横坐标为t，单位：s)。The coefficient matrix of the equation system (5) is a symmetric positive definite matrix, so there is a unique solution; from the formula a _k (k = 0, 1, ..., n) can be obtained, so that the polynomial can be obtained

The least squares polynomial fitting curve, that is, the active load fitting curve, is shown in Figure 7 and Figure 8 (the abscissa is t, unit: s).

The above are only specific embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (1)

1. A time delay curve fitting method based on non-time mark out-of-limit data transmission is characterized in that:

the method comprises the following specific steps:

step 1IEEE1588 synchronization protocol determination dynamic delay curve

The power plant clock is a master station master clock, the substation clock is a substation slave clock, and if the deviation between the master station master clock and the substation slave clock is constant and the transmission paths are symmetrical, the master station master clock and the substation slave clock are used as the transmission paths

t1+Delay＝t2+Offset (1)

t4＝t3+Offset+Delay (2)

Wherein t1 represents the command time of the master clock of the master station, and t2 represents the command time of the slave clock of the station receiving the command sent by t 1. (ii) a

t3 represents the time when the slave clock of the station gives a command, and t4 represents the time when the master clock of the station receives the command given by t 3. (ii) a

Delay represents network Delay of message transmission, and Offset represents deviation of a master clock and a slave clock;

the following can be obtained from formula (1) and formula (2):

Delay＝(t2-t1)+(t4-t3)/2 (3)

Offset＝(t4-t3)-(t2-t1)/2 (4)

obtaining deviation Offset between the slave clock and the master clock, and recording the deviation Offset as delta t, wherein at different moments, the coordinate points of the deviation delta t between the master clock and the slave clock form scattered point distribution, so that the slave clock is synchronous with the master clock;

step 2 synchronizing active loads

Forming scatter point distribution according to coordinate points of deviation delta t of a master clock and a slave clock, calculating the active load scatter point distribution of the synchronization of the slave clock of the transformer substation and the master clock of the power generation station according to the active load scatter point distribution condition transmitted between the transformer substation and the power generation plant, and then obtaining an active load curve through curve fitting;

step 3 Curve fitting

Suppose a given data point (x)_i，y_i)(i＝0，1，...，m)，x_iRepresents time t, y_iRepresents an active load P;

given m points, it is not required that the curve passes exactly through these points, but rather that the curve y ═ f (x) is approximated by a curve y ═ p (x);

calculating an approximation curve

So that the deviation I of the approximation curve p (x) at point I is minimal, i.e.

Namely, it is

Obtaining a in the formula (7)₀，a₁，...a_nObtaining I ═ I (a)₀，a₁，...a_n) To obtain a least squareAnd (4) fitting a polynomial fitting curve, namely an active load fitting curve.

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