JP2005151704A - Digital protective relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital protective relay capable of surely restarting a device, even when power is recovered, before a power supply voltage is dropped to a reset voltage. <P>SOLUTION: A circuit 1 for detecting the drop of the power supply voltage interrupts a CPU 2, when that the power supply voltage has dropped from a normal value is detected. A circuit 5 for detecting the power return of the power supply voltage detects the voltage status of the power supply. When the CPU is interrupted from the circuit for detecting the drop in the power supply voltage, the CPU executes processing before the stoppage of a system for evacuating data required for restarting the normal protection operation to a nonvolatile memory, executes power return check processing for determining whether the power supply has returned from a voltage state signal from the circuit for detecting the power return of the power supply voltage, after executing the processing before the stoppage of the system, and executes reset processing for restarting the device, when the determination of the power return is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital type protective relay device, and more particularly to a restarting method after a power failure / instantaneous interruption occurs in a device power supply.

  Digital protective relays are based on measured values (digital values) of currents and voltages such as short circuits / ground faults in power transmission / distribution systems and overcurrents in substation equipment. The protection operation (software processing) is used, and when protection is required, a protection output such as a tripping circuit breaker is obtained.

  Here, since the digital protection relay device is required to maintain a reliable protection function even in continuous operation, the device power supply must be designed and implemented with high reliability in addition to measures against power failure of the device power supply. Taken. As a measure against this power failure, providing an uninterruptible power supply for each protective relay device has the problems of increasing the cost and size of the device. As another power failure countermeasure, there is a restart method that saves data necessary for restarting the device when a power failure occurs (see, for example, Patent Document 1).

  This power failure countermeasure technique will be described with reference to FIG. (A) of FIG. 4 shows the principal part structure of a protective relay apparatus, (b) shows the time chart at the time of a power failure occurrence. The power supply voltage drop detection circuit 1 detects a power supply voltage drop due to the occurrence of a power failure or the like from the DC input of the control power supply, interrupts the CPU 2, and before the loss of the function of the CPU 2 or the like due to the drop of the DC output voltage of the control power supply 3, Pre-system stop processing is performed to save data (measurement data, arithmetic processing data, trip state data, etc.) necessary for resuming the protection operation from the RAM of the peripheral circuit 4 or the register of the CPU 2 to a nonvolatile memory (not shown). In addition, when the output of the control power supply 3 drops to the reset voltage (near zero voltage), the apparatus stops operating in hardware (reset state). When power is restored, the device is reset from the reset state and restarted, the saved data is read, and the protection operation is resumed.

Further, in the restart method, as shown in the processing flow of the CPU 2 when a power failure occurs in FIG. 4C, the CPU 2 executes the system stop pre-processing when a power failure occurs, and then executes an infinite loop process. There is also one that shifts to the reset state when the voltage of the control power supply 3 drops. The infinite loop process is executed when the CPU 2 accesses the peripheral circuit 4 such as the RAM while the power supply voltage is decreasing. Is intended to prevent undesired protective actions.
Japanese Patent Laid-Open No. 10-191547

  In the conventional restart method, data necessary for resuming normal protection operation is saved in a nonvolatile memory. Since the nonvolatile memory has a limited number of data writes, data is written only during power outages with extremely low occurrence frequency so that data writing is minimized.

  However, the power supply voltage drop occurs not only when a power failure occurs, but also when the power supply is interrupted. In this momentary power interruption, power may be restored before the voltage of the control power supply drops to the reset voltage. In this case, as shown in FIG. 5, when the voltage drop is detected by the voltage drop detection circuit 1, the CPU 2 enters an infinite loop process after the system stop pre-process, but if power is restored before the voltage drop reaches the reset voltage. The CPU 2 cannot escape from the infinite loop process (hangs up) and cannot be restarted.

  There is also a method to save data to a backup RAM with no limit on the number of writes, but if the power outage time is long, the backed up data may be destroyed or lost, and restart may fail There is.

  The object of the present invention is when the power is restored before the power supply voltage drops to the reset voltage in the restart method in which data necessary for normal protection operation restart is saved to the non-volatile memory in the event of a power failure or momentary power failure. It is another object of the present invention to provide a digital protective relay device that can be restarted reliably.

  In order to solve the above-mentioned problem, the present invention provides a voltage for detecting power supply voltage recovery, in addition to a conventional power supply voltage drop detection circuit, as a restart processing means when a power failure or instantaneous interruption occurs. A power supply voltage recovery detection circuit for detecting a state is provided, and the CPU executes a data saving process necessary for resuming normal protection operation when a voltage drop is detected, and then determines power recovery from the status signal of the power supply voltage recovery detection circuit. The system is sometimes restarted by executing a reset process, and has the following configuration.

(1) In the event of a power failure or momentary interruption of the device power supply, pre-system stop processing is performed to save the data necessary for device restart, and the device is restarted using the data when power is restored. A digital protective relay device having a restart processing means,
The restart processing means includes
A power supply voltage drop detection circuit that interrupts the CPU when it detects that the power supply voltage has dropped from a normal value;
A power supply voltage recovery detection circuit for detecting the voltage state of the power supply;
When there is an interruption from the power supply voltage drop detection circuit, the system stop pre-processing is executed, and after this execution, it is determined whether or not the power supply has been restored from the voltage state signal from the power supply voltage recovery detection circuit. And a CPU for performing a reset process for restarting the apparatus when a power recovery determination is obtained.

  As described above, according to the present invention, after executing the data saving process necessary for resuming normal protection operation when a voltage drop is detected, the system reset process is executed when power recovery is determined from the power supply voltage status signal. Therefore, when the power is restored before the power supply voltage drops to the reset voltage, such as a momentary power interruption, it can be reliably restarted.

  FIG. 1 is a block diagram of the main part of a digital type protective relay device according to the present invention. In FIG. 1, the difference from the configuration shown in FIG. The power supply voltage recovery detection circuit 5 for outputting a status signal indicating whether or not the power supply is present is provided, and the CPU 2 performs a reset process when the CPU 2 determines the power recovery from the output of the detection circuit 5.

  FIG. 2 shows a processing flow of the CPU 2 when a power failure or instantaneous interruption occurs. When there is an interruption by the power supply voltage drop detection circuit 1, the CPU 2 executes pre-system stop processing as in the conventional case (S1), and then performs power recovery check processing (S2).

  This power recovery check process determines whether or not the output of the power supply voltage recovery detection circuit 5 has changed from a voltage drop status signal to a power recovery status signal after the occurrence of an interrupt. If this determination result is not power recovery, power recovery check processing is repeated (S3).

  When the power recovery determination is obtained by repeating the power recovery check process, the CPU 2 performs a device reset process and restarts the device (S4).

  FIG. 3 shows a time chart when a power failure / instantaneous power interruption occurs. When the power supply voltage drop detection circuit 1 detects a voltage drop and an interruption occurs after the power supply voltage drop detection circuit 1 detects a voltage drop during the protection relay device protection process (time t1), the CPU 2 executes a system stop pre-process. Thereafter, when it is determined that the power has been restored before the reset process due to a momentary power interruption or the like (time t2), the reset process is immediately executed and the apparatus is restarted (t3).

  Further, after the system stop pre-processing is executed, the CPU 2 executes the reset processing when the power is not restored to the reset processing voltage due to a power failure or the like (t4), and restarts the apparatus after the power recovery (t5). .

  Therefore, according to the present embodiment, when power is restored before the power supply voltage drops to the reset voltage, the CPU 2 can immediately enter the reset process, and the system hangs without being able to escape from the conventional infinite loop process. Can be prevented and the protective operation can be resumed reliably. In addition, since the power recovery check process only determines the status output signal of the detection circuit 5 by the CPU 2, even if the RAM or the like to be referred to during the power recovery check process falls into an indefinite state, a reliable power recovery check and reset process are performed. Can be executed.

The principal part block diagram which shows the Example of this invention. An interrupt processing flow in the embodiment. The time chart at the time of a power failure in the embodiment and a momentary interruption. A configuration, a time chart, and an interrupt processing flow for explaining a conventional restart method. The time chart for demonstrating the malfunction response at the time of the conventional instantaneous interruption.

Explanation of symbols

1 Power supply voltage drop detection circuit 2 CPU
3 Control power supply 4 Peripheral circuit 5 Power supply voltage recovery detection circuit

Claims (1)

In the event of a power failure or instantaneous interruption of the device power supply, a system pre-shutdown process that saves the data necessary for device restart, and restarts the device using the data when power is restored A digital protective relay device comprising means,
The restart processing means includes
A power supply voltage drop detection circuit that interrupts the CPU when it detects that the power supply voltage has dropped from a normal value;
A power supply voltage recovery detection circuit for detecting the voltage state of the power supply;
When there is an interruption from the power supply voltage drop detection circuit, the system stop pre-processing is executed, and after this execution, it is determined whether or not the power supply has been restored from the voltage state signal from the power supply voltage recovery detection circuit. And a CPU for performing a reset process for restarting the apparatus when a power recovery determination is obtained, and a digital protection relay device.

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