CN101515922A - Method for transmitting dynamic process data of power networks in data acquiring-monitoring systems - Google Patents

Abstract

The invention discloses a method for transmitting dynamic process data of power networks in data acquiring-monitoring systems. The method comprises the following steps that: by performing lossy or lossless compression or sampling on data in a measurement period on RTU and other remote data acquisition terminals, a small amount of data is extracted to record the dynamic information of a system in the period; the extracted data is transmitted to a control center; and a dynamic process is reconstructed and displayed according to received data. The method has the advantages that the method remarkably reduces the amount of data extracted from dynamic process data in a data refreshing cycle, can characterize the data of dynamic process information, overcomes the problem that the prior system is low in the speed of refreshing monitoring information and incapable of accurately reflecting the dynamic changes of the power networks, can greatly lower the requirement on the bandwidth of communication systems, and can realize the real-time dynamic information transmission of power systems on the prior system.

Description

The transmission method of electrical network dynamic process data in the data acquisition and monitoring system

Technical field

The present invention relates to the dispatching automation of electric power systems technology, particularly the transmission method of electrical network dynamic process data in electric power system data collection and the supervisory control system (SCADA).

Background technology

(the Supervisory Control and Data Acquisition of data acquisition and monitoring system, SCADA) be to follow computer and development communication technologies and a kind of supervisory control system of coming, be widely applied to numerous areas such as electric power, water supply, oil, chemical industry, combustion gas and process control, wherein in dispatching of power netwoks, use the most general.Its remote data acquisition terminal (Remote Terminal Unit by being installed in power plant and transformer station, RTU) with monitored object---the state information (electric current, voltage, frequency, circuit trend, on off state and generator's power and angle etc.) of electrical network feeds back to control centre, abnormal state is reported to the police, and make a strategic decision and implement to control and offer help for the dispatcher.Generally speaking, when electrical network normally moved, the state information of data acquisition and monitoring system energy complete and accurate ground reaction electrical network helped the management and running personnel correctly to grasp system running state, in time follow the tracks of, adjust operation states of electric power system, become the indispensable instrument of power scheduling.

Because the data acquisition and monitoring system need realize being distributed on the wide region tens even the monitoring of thousands of electric currents, voltage, frequency, trend, on off state and the generator's power and angles etc. in a hundreds of transformer station and power plant, be subjected to the restriction of network service and Computer Processing capacity, can only refresh the demonstration electric network state in several seconds modes once.Change when little when electrical network is in normal operating condition and voltage, electric current, frequency, trend and generator's power and angle, the data acquisition and monitoring system can accurate response operation of power networks state.But when electrical network is short-circuited fault or other disturbance, the electric current of electrical network, voltage, frequency, circuit trend and generator's power and angle all may change fast, and refreshed the data acquisition and monitoring system that once show electric network state every several seconds this moment just can't the accurate response system dynamic course.This type of situation happens occasionally in the emergency of actual electric network is handled, and the typical dynamic process of some electrical network can not get effective observation as low-frequency oscillation in the data acquisition and monitoring system midium or long term, has seriously influenced the timely correct decisions of dispatcher.

In modern digital transformer station, the remote data acquisition terminal can receive measurement data such as each instantaneous electric current, voltage, frequency and generator's power and angle by communication network in the transformer station from the new-style electronic instrument transformer, and can calculate the circuit trend.Therefore, we can say that the data integrity ground of remote data acquisition terminal collection has comprised the information of electrical network dynamic process.But because the restriction of data acquisition and monitoring grid communication bandwidth, the complete data that comprise electrical network dynamic process information in the remote data acquisition terminal all can not be sent to control centre, present electric network data collection and supervisory control system can only every several seconds in the monitored object Refresh Data cycle a certain instantaneous Refresh Data show electric network state, so the information of electrical network dynamic process disturbance is provided can not for the management and running personnel time.A kind of feasible selection of head it off be from Refresh Data in the cycle dynamic process extracting data go out the data that data volume significantly reduces and can characterize dynamic process information, reduce requirement by transmitting data that these data volumes significantly reduce, reach the purpose that dynamic process of electrical power system information is communicated to control centre communication system.

Summary of the invention

The objective of the invention is on data acquisition and monitoring system existing hardware facility basis, to improve the ability of its reaction system dynamic process, to improve the observability of electrical network dynamic process in the data acquisition and monitoring system, improve the ability of dispatcher's solution of emergent event and quick correct decisions.

For achieving the above object, the technical solution adopted in the present invention is: in the data acquisition and monitoring system in each refresh cycle, adopt modes such as data compression or sampling in the remote data acquisition end side, extract the information that the less data of data volume write down this Refresh Data dynamic process of electrical power system in the cycle, and the data of extracting are sent to the control centre, to reduce transmitted data amount, reduce requirement to communication system.Then in control centre according to the data reconstruction and the display system dynamic process that receive.

The technical method that reduces data volume mainly contains data compression or sampling of data etc., its purport is with dynamic process of electrical power system in the less data record data refresh cycle (electric current, voltage, merit angle, frequency and trend) information, and these data are sent to control centre, then in control centre according to the data reconstruction dynamic process of electrical power system that receives, reach that reduction requires communication system and the purpose of transferring electric power system dynamic course information on the existing system basis.Wherein, data compression method can be selected lossy compression (Technology of Data Fitting etc.) or lossless compressiong (Huffman coding, arithmetic coding, run length encoding, LZW coding compression algorithm etc.) for use, carries out data reconstruction by the data that receive or decompresses and to recover the dynamic process data in control centre then; Sampling can adopt uniform sampling and inhomogeneous sampling to obtain low volume data point in the dynamic process data, utilizes interpolation reconstruction real system dynamic process data in control centre then.Owing to only transmit data compressed or that sampling back data volume significantly reduces, can effectively reduce the traffic load of power telecommunication network network.Institute of the present invention extracting method can be aided with necessary software transformation on available data collection and supervisory control system basis is implemented.Because institute's extracting method data packets for transmission contains dynamic process of electrical power system information, so adopt the data acquisition and monitoring system of this method can react dynamic process of electrical power system truely and accurately.

The present invention compared with the prior art, the most outstanding advantage is to represent the dynamic process of electrical power system information that available data collection and supervisory control system can't show, and helps the electrical network dynamic processes such as recovery, vibration and unstability after the management and running personnel simple and direct observation disturbance; Secondly, this method can realize on data acquisition and monitoring system existing hardware system-based, need not set up special-purpose communication network; At last, simple because this method only need be carried out corresponding transformation to software systems, can select specific monitoring target to implement flexibly separately.

Description of drawings

Fig. 1 is emulation WEPRI 36 node electrical network figure.

Fig. 2 is by the per voltage fluctuation of demonstration and comparison diagram of 31 node virtual voltage dynamic processes of refreshing in 3 seconds on available data collection and the supervisory control system.

Fig. 3 be in 31 node remote data acquisition terminals to voltage dynamic process data by transmission polynomial coefficient only behind the 9 rank fitting of a polynomials, again in control centre according to the data of multinomial coefficient reconstruct and the comparison diagram of 31 node virtual voltage dynamic processes.

Embodiment

Emulation WEPRI 36 node electrical network figure as Fig. 1.Among this figure: the electrical power system transient emulation that utilizes the electric system simulation analysis software to carry out electrical network generation three phase short circuit fault and remove fault.In the time of 0.01 second, be engraved in circuit generation bolted three-phase fault between 30 nodes and 31 nodes, excised fault then in 0.1 second constantly.The voltage data of 31 nodes that emulation is obtained is step-length output with 10 milliseconds, and this voltage data handled with available data collection and supervisory control system working method and this patent institute extracting method respectively, with performance this patent method in the effect of showing on the electrical network dynamic process information.

Fig. 2 is by the per voltage fluctuation of demonstration and comparison diagram of 31 node virtual voltage dynamic processes of refreshing in 3 seconds on available data collection and the supervisory control system.Wherein, dotted line for 10 milliseconds be 31 node voltage dynamic process data of step-length output, solid line is for by available data collection and supervisory control system data transmission method, the 31 node voltage change curves that observed when refreshing the display system state in per 3 seconds.At this, refresh the electric network state of the whole Refresh Data of demonstration in the cycle with initial transient data of Refresh Data cycle, what promptly constantly saw at 0～3 second is 0 second voltage constantly, and what constantly saw in 3～6 seconds is 3 seconds voltage constantly, and the rest may be inferred.As can be seen from Figure, the obvious representation system dynamic process truely and accurately of the mode that shows of available data collection and supervisory control system refresh data.

Fig. 3 be in 31 node remote data acquisition terminals to voltage dynamic process data by transmission polynomial coefficient only behind the 9 rank fitting of a polynomials, again in control centre according to the data of multinomial coefficient reconstruct and the comparison diagram of 31 node virtual voltage dynamic processes.Wherein, dotted line is for being the 31 node voltages fluctuation data of step-length output with 10 milliseconds, solid line for adopt that this patent proposes diminish polynomial fitting method packed data in the data compression method after, 31 node voltage delta datas that obtain according to the multinomial coefficient reconstruct that receives in control centre again.Fit to example explanation specific implementation process at this with 9 rank polynomial datas.On the remote data acquisition terminal to data in the refresh cycle dynamic process data of system mode carry out data fitting (herein only with 9 rank polynomial data approximating method expression effects).

The polynomial data match is to come match given data D with polynomial function (1),

f(x)＝θ ₀+θ ₁x+θ ₂x ²+θ ₃x ³+...+θ _nx ⁿ (1)

Write as matrix form (2)

D＝θX+ε (2)

$D=\left[\begin{array}{c}{d}_1\\ d_2\\ ...\\ d_M\end{array}\right],$ $\mathrm{\θ}=\left[\begin{array}{c}{\mathrm{\θ}}_0\\ {\mathrm{\θ}}_1\\ ...\\ {\mathrm{\θ}}_N\end{array}\right],$ $X=\left[\begin{array}{ccccc}1& x_1& x_1^2& ...& x_1^n\\ 1& x_2& x_2^2& ...& x_n^2\\ ...& ...& ...& ...& ...\\ 1& x_M& x_M^2& ...& x_M^n\end{array}\right],$ $\mathrm{\ϵ}=\left[\begin{array}{c}\underset{i=0}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\θ}}_i{x}_1^i-d_1\\ \underset{j=0}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\θ}}_i{x}_2^i-d_2\\ ...\\ \underset{j=0}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\θ}}_i{x}_M^i-d_M\end{array}\right]$

Wherein ε is an error of fitting, θ is coefficient to be asked, polynomial fitting exponent number N is 9, X is M the sampled point moment (M=300 in the data refresh cycle, per 10 milliseconds of 1 data in 3 second cycle), D is the 31 node voltage dynamic process data that 300 instantaneous voltage data in the data refresh cycle constitute.Adopt least square method can try to achieve the multinomial coefficient θ that makes fitting data and electrical network dynamic process data mean square error minimum.Main website of data acquisition and monitoring system lateral root can be by polynomial function (1) reconstruct electrical network dynamic process according to the multinomial coefficient θ that receives.

Available data collection and supervisory control system are with each Refresh Data cycle 1 magnitude of voltage characterization system state; Each Refresh Data cycle need be transmitted 9 coefficients of polynomial fitting when adopting 9 rank multinomials, and data volume is available data collection and supervisory control system 9 times; With respect to the whole instantaneous voltage data of transmission, data volume is 9/300, promptly 3% of whole 300 instantaneous voltage data in the transmission 3 seconds.By Fig. 2 and Fig. 3 as seen, this patent method can reach the remarkable purpose of improving electrical network dynamic process monitoring capability with a small amount of increase of amount of communication data.Because relative available data collection of data volume and supervisory control system increase little, patented method can be implemented on available data collection and supervisory control system basis.

Claims (4)

1, the transmission method of electrical network dynamic process data in a kind of data acquisition and monitoring system, may further comprise the steps: the measurement data of data in the refresh cycle adopted technology such as data compression or sampling in the remote data acquisition end side, extraction comprises the less data of data volume of dynamic process of electrical power system information in the Refresh Data cycle, and with these transfer of data to control centre, recover according to the data that receive or reconstruct data electrical network dynamic process data in the refresh cycle in control centre again.

2, the transmission method of electrical network dynamic process data in the data acquisition and monitoring according to claim 1 system, it is characterized in that: destructive data compressing methods such as monitoring target dynamic process The data Huffman coding, arithmetic coding, run length encoding, LZW are compressed the dynamic process data in the remote data acquisition end side, data after the transmission compression are to reduce the requirement to communication system, the data decompression in control centre again to receiving, reconstruct electrical network dynamic process data.

3, the transmission method of electrical network dynamic process data in the data acquisition and monitoring according to claim 1 system, it is characterized in that: in the remote data acquisition end side to lossy compressions such as monitoring target dynamic process The data data fittings, less and the data that can react electrical network dynamic process information of the data volumes such as coefficient of transmission fitting function to be to reduce the requirement to communication system, again in control centre by the data reconstruction electrical network dynamic process data such as fitting function coefficient that receive.

4, the transmission method of dynamic process of electrical power system data in the data acquisition and monitoring according to claim 1 system, it is characterized in that: to monitoring target dynamic process The data evenly or nonuniform sampling extracting part divided data in the remote data acquisition end side, the transmission data from the sample survey is carried out interpolation reconstruction electrical network dynamic process data in control centre by the data that receive again to reduce the requirement to communication system.

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