JPH0217821A - Digital type protective relaying device - Google Patents

Abstract

PURPOSE:To operate a CPU efficiently by providing a timer apart from the CPU and performing the clearance of a counter and the start and stop of counting-up by a signal from the CPU. CONSTITUTION:A CPU 12, a timer 13 and a memory 14 are connected on a CPU board 11 through a bus 15. The timer 13 is a timer of a hardwear to count up every certain hours, and the clearance of a counter and the start and stop of counting-up are performed by a control signal 16 from the CPU 12. Once the timer 13 receives a command signal of the start of counting-up, the counting-up continues until the timer receives a command signal of the stop. Accordingly, during the operation of the timer, the CPU 12 can make another process other than a timer process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention is directed to a digital protective relay system for detecting power system faults and protecting the power system.

(Prior art) A digital protective relay device that protects a power system samples and digitizes the amount of electricity in the power system, and detects an accident by performing predetermined calculations based on this digitized data. ing. FIG. 5 is a diagram showing the configuration of a conventional digital protective relay device.

In FIG. 5, the amount of electricity in the system is sampled at fixed time intervals (hereinafter referred to as one sampling time). Therefore, it is necessary to complete a predetermined calculation within one sampling. For this reason, the following method has conventionally been used to measure the time taken when a predetermined calculation is executed (hereinafter referred to as calculation time).

From the end of a given calculation until the start of the next calculation, the software counts up the counter,
Measure the remaining time from the end of the calculation to the start of the next calculation.

FIG. 6 is a diagram showing the remaining time, and when the time 62 of the calculation section is selected as shown in the figure within one sampling time 61, the remaining time becomes a period indicated by 63.

FIG. 7 is a diagram showing software processing for measuring remaining time. As shown in the figure, a predetermined calculation is performed in step 71, and after the calculation is completed, a counter for measuring the remaining time is cleared in step 72, and in steps 73 and 74.
The count is counted until one sampling time ends at step 75, and after the end, the value is stored at step 75. The remaining time in this case can be determined by multiplying the counter value by an appropriate constant. Note that the calculation time is the value obtained by subtracting the remainder time from one sampling time.

(Problems to be Solved by the Invention) In the case of the conventional device described above, the CPU performs a count-up process on the counter during the remaining time.

Therefore, it has the disadvantage that it cannot be processed without any need for other processing, such as sampling data.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a digital protective relay device that can measure calculation time and efficiently operate a CPU.

[Structure of the Invention] (Means for Solving the Problems) To explain the structure for achieving the above object, the present invention takes a sine wave alternating current from a power system as input, and samples this sine wave alternating current at predetermined time intervals. In a digital protective relay device that converts this sampling value into digital data and then performs a predetermined protection calculation in a central processing unit, when the central processing unit starts calculation, an external activation signal is sent. A start signal output means for outputting a signal, a stop signal output means for outputting a stop signal to the outside when the calculation ends, and a timer that starts counting at a predetermined period upon reception of the start signal. , a counter that stops the timer upon reception of the stop signal and counts the number of counts during that time, and a display means that displays the counted number to the outside.

(Function) First, the timer starts counting by a start signal output when the central processing unit starts calculation. This counting continues until the central processing unit finishes the calculation and outputs a stop signal. Therefore, the calculation time is determined by the count number of the timer. This determined count number is displayed on an external display device.

(Example) Examples will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a CPU board applied to a digital protection electronic device according to the present invention.

In FIG. 1, 11 is a CPU board, which connects CPU 12 . A timer 13 and memory 14 are connected. The timer 13 is a hardware timer that counts up at regular intervals, and clears the counter and starts and stops counting up in response to a control signal 16 from the CPU 12. Once the timer 13 receives a command signal to start counting up, it continues counting up until it receives the next command signal to stop. Therefore, while the timer 13 is operating, the CPU 12 can perform processing other than timer processing. Note that timer 1
Through the start and stop processing in step 3, it is possible to measure the time required for a predetermined calculation.

FIG. 2 is a flowchart showing the calculation and measurement procedure. First, when the conversion of the amount of electricity in the system into digital data is completed, the CPU starts a predetermined relay calculation. At the beginning of this calculation process, the counter of the timer is cleared (step 21), and then a count-up signal is sent to the timer (step 22).

Upon receiving this signal, the timer 13 continues to count up at fixed time intervals, regardless of the operation of the CPU 12.

Thereafter, when the CPU completes the predetermined arithmetic processing (step 23), it sends a count-up stop signal to the timer 13. Upon receiving this signal, the timer 13 stops counting up (step 24). After this, CPU12
or read the count value of timer 13 (step 25),
Store it in the memory 14.

Fig. 3 is a diagram showing the relationship between arithmetic processing and timer count values. In Fig. 9, point A is the start time of relay arithmetic processing, and B
This point is the end point of the relay calculation process. The counter is A
Start counting up from point B and stop counting up at point B. The count value at this time becomes a value proportional to the calculation time. Therefore, by displaying the count value stored in the memory on an external display device (for example, a 0 display) as necessary, the calculation time can be obtained without using a special external measuring device. The actual calculation time is the counter value multiplied by the time required for the timer to count up. For example, if the counter is 0
．． When counting up every 54+s, if the above counter value is 2500, the calculation time is 2500x0.5
It can be calculated that μs=1250gs.

According to this embodiment, the CPU can perform other processing, such as processing related to monitoring, during the remaining time between the end of a predetermined calculation and the start of the next calculation, thereby creating an efficient program. I can do it.

FIG. 4 is a block diagram of another embodiment of the present invention.

In this embodiment, there are three CPU boards. Each CPU
The substrates 41, 42, and 43 have a computation time measurement function as in the previous embodiment, and store the count value of the computation time in the memory. It is assumed that each CPU can read the contents of memory on other CPU boards.

Therefore, the CPU of the CPU board 41 reads the calculation time measurement results stored in the memories of the other CPU boards 42 and 43, performs a predetermined process, for example, the process of determining the maximum value of the calculation time of each CPU, and performs processing as necessary. and display it on an external display device (for example, an LED display). As a result, in a multigrossing system in which a plurality of CPUs operate simultaneously, one CPU can constantly monitor the calculation time of other CPUs. Note that it is clear that the same applies even if the number of CPU boards is other than three. Also,
The timer for measuring calculation time is not limited to a timer provided outside the CPU, but also a timer that is built into the CPU chip and counts with the same clock as the CPU can be used to obtain the same function as in the above embodiment. .

[Effects of the Invention] As explained above, according to the present invention, a CP is formed on a CPU substrate.
A timer separate from the CPU is provided, and the counter is cleared and the count-up is started and stopped using signals from the CPU, so the calculation time can be measured without stopping the protective relay function. By displaying the data on the display device without using external measuring equipment, the calculation time can be constantly monitored, and during the remaining time, the CPU performs other processing, making it possible to monitor if the calculation time is over. It is possible to provide an efficient protective relay device with more functions.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of a CPU board applied to a digital protective relay device according to the present invention, Fig. 2 is a diagram showing software processing for measuring calculation time, and Fig. 3 is a diagram showing calculation time. Figure 4 shows the configuration of another embodiment, Figure 5 shows the configuration of a conventional digital protective relay device, and Figure 6 shows the relationship between one sampling time and the remaining time. The diagram shown in FIG. 7 is a diagram showing software processing for measuring calculation time according to the conventional technology.
-CPU board 12・CPU13...Timer 14...Memory 15...Bus

Claims (1)

[Claims] A digital protective relay that inputs the sine wave alternating current from the power system, samples this sine wave alternating current at predetermined time intervals, converts this sampling value into digital data, and then performs a predetermined protection calculation in the central processing unit. In the device,
a start signal output means for outputting a start signal to the outside when the central processing unit starts a calculation; a stop signal output means for outputting a stop signal to the outside when the calculation ends; A counter that starts a timer that counts at a predetermined period upon reception of the start signal, stops the timer upon reception of the stop signal, and counts the number of counts during that time, and displays the counted number externally. What is claimed is: 1. A digital protective relay device, characterized in that it is equipped with a display means.