JPH07294589A - Method for collecting electricity quantity information on power system failure - Google Patents

Abstract

PURPOSE:To collect stable data by sampling data from the time when a failure occurs and checking the data of change amount before and after a certain time taking the data at at the certain time as the reference. CONSTITUTION:For example, when collecting data for plotting a failure point using a digital processing device such as a computer, a current value at a time (tr) which is later by a specific amount of time from a failure occurrence point, for example, which is considered to be the time when data fully stabilize, is set to In-m and the current is set to a reference value Iref (¦lref¦=¦In-m¦). Then, the absolute value which is the difference between data In-m+a which is later than the reference value In-m by a time (a) and the reference value Iref is compared with the absolute value which is the difference between the data In-m-b which is a time (b) before and the reference value Iref and then data at the time when either becomes smaller are adopted as the data for reliable plotting. Then, data are collected by N+1 samples (0 to N).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electric power when a quantity of electricity such as voltage, current and impedance is collected by using a short time until a breaker operates in a power system. The present invention relates to a method of collecting information on the amount of electricity when a system failure occurs.

[0002]

2. Description of the Related Art Conventionally, a system shown in FIG. 4 is known as a system of this type. FIG. 4A is a schematic diagram showing the outline thereof, and FIG. 4B is a waveform diagram for explaining the operation. That is, a failure detection relay (hereinafter, also simply referred to as a relay) 1 and a timer 2 are provided as shown in FIG. 9B, and if the failure detection relay 1 operates due to a failure occurrence as shown in FIG. The timer 2 is operated for a fixed time T after the time t, and data is collected during this period. This is based on the premise that the amount of electricity after a certain time t after the operation of the failure detection relay 1 is stable and the error should be small.

[0003]

However, in the above method, the stable time of the electric quantity data varies depending on parameters such as the failure mode, the failure duration time, and the operation time of the failure detection relay, that is, the constant time t. Is not constant and varies under various conditions, it is unknown whether the data at that time is the most stable, and there is a problem that unstable data may be collected. Therefore, an object of the present invention is to collect data as stable as possible.

[0004]

In order to solve such a problem, according to the present invention, the operation of a fault relay installed in a power system and operating at the time of occurrence of a fault is monitored, and the voltage and current are included from the time when the fault relay operates. After collecting the amount of electricity for a certain period of time with a certain sampling period and storing it in a predetermined memory, the stored amount of information is based on the amount of electricity at the time after a predetermined time from the occurrence of the failure, and before and after that. Sequentially comparing the difference with the reference value of the amount of electricity, execute the process of selecting the amount of electricity at the time corresponding to the smaller one for a certain period of time,
It is characterized in that the information during this period is adopted as the normal data for various calculations including the fault location calculation.

[0005]

[Function] Since a predetermined amount of electricity data is sampled from the time of occurrence of a failure and data is actually stable from the change state of the data before and after the predetermined time after the data is used as a reference, Also makes it possible to obtain highly reliable data, and to perform fault location calculation and the like with high accuracy.

[0006]

1 is a flow chart showing an embodiment of the present invention. Here, it is assumed that a digital processing device (fault point locating device) such as a computer is used to collect data for performing the fault point locating. Therefore, FIG. 1 shows the operation of the fault point locating device. It can be said to show.
In addition, here, the current is mainly considered as the quantity of electricity.

First, at step S1, a failure occurrence time t0
After a predetermined time from, for example, the time at which the data is considered to be sufficiently stable, the current value at time tr is
_nm, and this as a reference value I _ref (| I _ref | = |
I _nm |). Note that | I | indicates the absolute value of I. next,
Initialization is performed by setting the loop counter x to 0 and the arguments a and b to 0 (steps S2 and S3).

In step S4, the difference || I between the reference value I _ref and the data I _{n-m + a} after time a on the right side of the reference value I _{nm.
n-m + a} |-| I _ref ||, left side data I before time b
Difference between _nmb and reference value I _ref || I _nmb |-| I _ref
|| are compared with each other, and the data at the time of whichever is smaller is adopted as the data for reliable orientation (steps S5 and S6). After that, arguments a and b
(B = b + 1, a = a + 1) and the loop counter x are updated (x = x + 1) to collect data for N + 1 samplings (0 to N) (step S7,
S8, S9, S10).

FIG. 2 shows the situation at this time in an easy-to-understand manner.
Shows the relationship between each time and the data at each time. Here, the time n-2m and the data value I at that time
_n-2m , reference time nm and data value I at that time
_nm , time n, and the data value I _{n at} that time are shown. It should be noted that each time is sequentially updated in the order of n-2m, nm, and n.

FIG. 3 is a waveform diagram for explaining the concept of the present invention. (A) is the output voltage of the transformer (PT), (b) is the output current of the current transformer (CT), and (c) is The filter output voltage, (d) is the filter output current, (e) is the calculated value of the effective current value, (f) is the output of the failure detection relay, and (g) is a waveform example showing the orientation accuracy. Therefore, it can be said that here, PT and CT are installed in the power transmission line, and filters are provided at the outputs thereof to shape the waveform.

That is, as shown in FIG. 3, when a system failure occurs at time t0, the waveforms of the respective parts are (a) to (d) in FIG.
The calculation result of the effective value of the current is shown in the figure (e),
The operation waveform of the failure detection relay is as shown in (f) of the same figure.
The shaded portion in (f) indicates the period when the operation of the failure detection relay is unstable. Therefore, the period excluding this period, that is, the time between the time t1 and the time t2 in the figure, indicates the effective current value. It can be seen that if the calculation is performed, the orientation calculation error can be reduced as shown in FIG.

By the way, conventionally, the data is taken after a certain period of time in which the data will be stable from the time t0 at which the system failure occurs. It varies depending on each parameter such as time and operating time of the failure detection relay. For this reason,
In the present invention, the data after a certain period of time is used as a reference, the data before and after that is actually checked, and the data at the time when the variation is small is adopted.

However, even in this case, it is unavoidable that this data contains an error depending on the system harmonics and transient components. Therefore, the data for a plurality of time points are not used for the orientation calculation for one shot with the data for one shot. It is desirable to take measures such as carrying out orientation calculation a plurality of times using the average value, and taking the average value.

Although the current and voltage of the system have been focused on in the above, it is also possible to focus on other electrical quantities such as impedance. Moreover, although there are three-phase currents, zero-phase currents, and the like, even if it is called a current, which of them is to be focused on is, for example, as follows according to the failure mode.

(1) With a short circuit and a two-phase ground fault, a large positive-phase current flows in the fault phase (two or more phases). Therefore, the phase in which the maximum line-to-line current flows (line-to-line) is taken as the failure phase and attention is paid to that phase. (2) At 1-line ground fault, pay attention to the zero-phase current. In particular, in the high resistance grounding system, the fault current at the time of one-line ground fault is small, so the fault current is mixed in with the load current. Therefore, the zero-phase current that is not affected by the load current is used.

[0016]

According to the present invention, data is sampled from the time of occurrence of a failure and the amount of data change before and after that is checked with reference to the data after a fixed time, so that the data is actually stable. It is possible to know whether or not there is, and it is possible to obtain highly reliable data. As a result, there is an advantage that it is possible to perform highly accurate orientation calculation.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the concept of the present invention.

FIG. 3 is a waveform chart for explaining an embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining a conventional example.

[Explanation of symbols]

 1 ... Failure detection relay, 2 ... Timer.

Claims (1)

[Claims] 1. A predetermined memory that monitors the operation of a fault relay that is installed in a power system and that operates when a fault occurs, and collects the amount of electricity including voltage and current for a certain period of time with a certain sampling period from the time when the fault relay operates. Of the stored information, the electric quantity at a predetermined time after the occurrence of the failure is used as a reference, and the difference between the electric quantity before and after the reference value is sequentially compared, and the smaller one is selected. Electricity information at the time of a power system failure, characterized by executing the process of selecting the electricity quantity at the corresponding time point for a certain period of time and adopting the information during this time as regular data for various calculations including the fault point calculation Collection method.