JPH0756501B2 - Synchronous measurement method for different point information - Google Patents

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to a synchronous measurement method of different point information for synchronizing each piece of information independently measured at different points and using it for processing of phenomenon analysis and characteristic grasp.

[Prior art and its problems]

A plurality of pieces of measurement information measured at different points are used for monitoring the state of the power system and for protection control. Although this measurement information changes when a failure or the like occurs in the target system, not only the measurement information when the change occurs but also the measurement information after the change may be needed. For example, in the fault location, the value of the ongoing fault is used as the measurement information. For this reason, conventionally, the measurement information measured at different points is collected in one place and used for the process of phenomenon analysis and characteristic grasp. However, according to such a method, since there is a delay due to transmission, the measurement information at each point is not synchronized, and therefore there is a problem in accuracy of phenomenon analysis and characteristic grasp. Particularly in fault location, since the measurement information measured at the two terminals of the system is a vector quantity, it is necessary to synchronize the measurement information at each point when performing vector calculation.

[Object of the Invention]

In view of the above, the present invention sets the measured values at different points to 1
It is necessary to provide a synchronous measurement method of different point information that enables the same relationship in time, that is, equivalent to the synchronized measurement, when used collectively at one place or a plurality of different places. To aim.

[Points of the Invention]

The present invention has been made by paying attention to the fact that when a failure or the like occurs, the data measured at different points will have a state change corresponding to the failure or the like at the same time point, and at different points asynchronously at a constant cycle. When sampling data, measure the time interval between the time when a state change is detected in the data and the previous or next sampling time, and synchronize the sampled data based on this time interval. It is a feature.

Examples of the invention

FIGS. 4 (a) and 4 (b) are explanatory diagrams of the phase of the data sampled at a constant cycle, and the two terminals A and B of the system.
Of these, (a) shows the voltage of the A terminal and (b) shows the current of the A terminal. In the figure, if two electric quantities at 90 ° intervals at the A terminal are (V ₁ ^A , V ₂ ^A ) and (I ₁ ^A , I ₂ ^A ), 90
The maximum values V ^A , I ^A from the two electrical quantities at intervals of ° and the phases θ _VA , θ _IA from the zero point of the waveform to the sampling can be obtained as follows. First, regarding voltage, V ₁ ^A = V ^A sin θ _VA V ₂ ^A = V ^A sin (θ _VA + π / 2) = V ^A cos θ _VA Similarly, for the current, I ₁ ^A = I ^A sin θ _IA I ₂ ^A = I ^A sin (θ _IA + π / 2) = I ^A cos θ _IA Represents ∠ and (θ _IA -θ _VA) | In order to perform vector operations, when to adjust the phase of each electrical quantity and a reference voltage ^{V A, A = | V A} | ∠0 °, ^{A =} | I ^A be able to. Similarly, the following equation holds for the B terminal. ^{B =} | V ^B | ∠0 ° ^{B = | I B | ∠ (} θ IB -θ VB) Here, when we consider the phase of the data sampled by the A terminal and the B terminal, the A terminal and the B terminal The sampling data are not synchronized because they are individually sampled. FIGS. 5 (a) and 5 (b) are explanatory views of the phase relationship between the voltages V ^A and V ^B measured at the A terminal and the B terminal. FIG. 5 (a) is a waveform of the voltage V ^{A at} the A terminal, and FIG. ) Indicates the waveform of the voltage V ^{B at} the B terminal. As is clear from the figure, the sampling timing (t ₁ , t
₂ , t ₃ ……) are out of phase. However, at the time t _F when the failure occurs, both the voltages V ^A and V ^B change at the same time. Therefore, in the present invention, the time (Δt _A , Δt _B ) from the time when the failure detection signal is output to the first sampling time is measured with a timer based on the failure detection signal which is a simultaneous signal at each terminal. , The time difference of this timer (Δt = Δt _A
-Δt _B ), that is, the amount of sampling deviation is used to synchronize the data at the A and B terminals. In Figure 5, the voltage V ^A, a phase difference .phi.V ^AB of V ^{B _{is, φV AB = (θ VB -2πfΔt}} B) - (θ VA -2πfΔt A) = (θ VB -θ VA) + 2πfΔt similarly, A The phase difference φI ^AB between the terminal voltage V ^A and the terminal B current I ^B can be expressed as φI ^AB = (θ _IB −θ _VA ) + 2πfΔt. When the voltage V ^A is used as a reference here, ^A = | V ^A | ∠0 ° ^A = | I ^A | ∠ (θ _IA −θ _VA ) ^B = | V ^B | ∠ {(θ _VB −θ _VA ) + 2πfΔt} ^{B =} | I ^B | can be expressed by taking _{∠ {(θ IB -θ VA)} + 2πfΔt} strains a terminal so on, the voltage measured at the B terminal, a synchronous current. In the above description, the time from the output time of the failure detection signal to the next sampling time is measured, but the time from the sampling time to the output time of the failure detection signal may be measured. Of course. Next, the terminal device installed in each terminal of the system configured to measure the time from the time when the failure detection signal is output to the first sampling time will be described. FIG. 1 is a block diagram showing an embodiment of a terminal device installed at each terminal. In the figure, 1 is a transformer, 2 is a current transformer, and 3 and 4
Is an analog filter, 5 is sampling means, 6 is an analog / digital converter (hereinafter referred to as AD converter), 7 is a digital filter, 8 is a first memory for storing sampled data, and 9 is for transmission. A second memory, 10 for storing data selected from the first memory 8
Is a failure detection means, and 11 is a timer for measuring the time from the failure detection time to the next sampling. In such a configuration, the voltage amount and current amount of the system are taken in by the transformer 1 and the current transformer 2 and sampled at a constant period (for example, 30 ° intervals) by the sampling means 5 via the analog filters 3 and 4. It The sampled data is converted into a digital amount by the AD converter 6 and then applied to the digital filter 7 to remove harmonic components and DC components and stored in the first memory 8. Meanwhile, the transformer
1, the data taken in by the current transformer 2 is inputted to the failure detecting means 10 and the failure is detected. The failure detection means 10 is the second
As shown in the figure, the filter 12 that inverts the input and delays by half cycle, the resistors 13 and 14, the level detector 15, and the output signal of the level detector 15 are held for two cycles and output. And an output circuit 16 for controlling the output. 3A and 3B are explanatory diagrams of the operation of the failure detecting means 10. FIG. 3A shows a normal time and FIG. 3B shows a failure occurrence time. Failure detection means
Because 10 is normal is inverted by the filter 12 to the input I ₁ Toko input I ₁ as shown in FIG. 3 (a), the absolute value of the input I ₂ obtained by delaying the equal polarities are opposite, Level detector
The input of 15 is zero because I ₁ −I ₂ = 0, and the failure detection signal is not output from the output circuit 16. On the other hand, when a failure occurs at time t _F as shown in FIG. 3B, I ₁ −I ₂ ≠ 0 because I ₁ and I ₂ are different in magnitude, and the level detector 15 Is applied to the output circuit 16 to output a failure detection signal. This failure detection signal is applied to the timer 11 and the first memory 8. The timer 11 is configured to start counting when a failure detection signal is input and stop counting when the next sampling signal is input. Therefore, the timer 11 counts the time from the output of the failure detection signal to the input of the next sampling signal. Further, when the failure detection signal is input, the first memory 8 selects the data required for locating the failure point and outputs it to the second memory 9. Here, the data necessary for fault location is, for example, 2
There are two quantities at 90 ° intervals after the cycle and two quantities at one cycle before the failure. The reason why the two quantities after two cycles from the time of the failure occurrence are used is that two cycles are necessary for the filtering process, and the two quantities of the one cycle before the failure occurrence are used to eliminate the zero-phase circulating current. This is because. Second
The memory also stores the count value of the timer 11 and the trip number of the protection relay of the system. This trip number is used to determine whether or not the change in the data captured by the failure detection means 10 is due to an actual failure.
The selection data from the first memory 8 stored in the second memory, the count value of the timer 11 and the trip number are transmitted to the central unit. The central device receives data from each terminal device, obtains the sampling deviation amount in each terminal device from the count value of the timer of each terminal device, and samples the sampling data according to this deviation amount. After correcting the error and synchronizing the sampling data from each terminal device, the phenomenon is analyzed and the characteristics are grasped (in the case of fault location, the location of the fault point is calculated), and the output is judged by the presence or absence of the trip signal. In the above description, the data of each terminal device is transmitted to the central device, but without providing the central device, the data of one terminal device is transmitted to the other terminal and the sampling data is synchronized there. Needless to say, fault point localization may be performed by using the above method.

【The invention's effect】

According to the present invention, the time interval from the failure detection time point to the previous or next sampling time point is measured at each different point, and the sampling data of each different point is corrected based on the measured time so that synchronization is achieved. Since it is configured, it becomes possible to handle the sampling data in the same manner as the data measured synchronously, and it is possible to improve the accuracy of phenomenon analysis and characteristic grasp.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a terminal device used in the present invention, FIG. 2 is a block diagram showing the configuration of failure detection means, and FIG. 3 is a waveform diagram for explaining the operation of the failure detection means. Fig. 4 shows the explanation of the phase of sampling data, No. 5
The figure shows an explanatory diagram of the phase relationship of the data sampled by each terminal device. 1: Transformer, 2: Current transformer, 3,4: Analog filter, 5: Sampling means, 6: AD converter, 7: Digital filter, 8: First memory, 9: Second memory, 10: Failure detection Means, 11: Timer, 12: Filter, 13, 14: Resistor, 15: Level detector, 16:
Output circuit.

Front page continued (72) Inventor Mitsuo Saito 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Inventor Shigeru Narita 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (1)

[Claims] 1. A terminal device is installed at each of different points, and each terminal device asynchronously samples data at a constant period when a state change due to a failure or the like occurs, and a state change in the data. Means for measuring the time interval between the time when the occurrence of and the previous or next sampling time;
A means for transmitting predetermined sampling data and the measurement time to a predetermined place is provided, and at the predetermined place, the transmitted sampling data is synchronized based on the measurement time, and synchronous measurement of different point information is performed. method.