JPH0152971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection and monitoring device for inspecting and monitoring an input circuit of a protective relay device.

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 is the power transmission line 1a that forms the system.
2 is a current transformer that transforms the current of 2, windings 2a, 2b,
2c, a transformer with winding 2a connected to current transformer 1, 3 a contact that is connected to winding 2b and closed during inspection, and 4 connected to winding 2b through contact 3. A power supply 5 is a digital protective relay device, a filter section 6 connected to the winding 2c extracts the fundamental wave component of the current, and an analog-to-digital conversion (hereinafter referred to as ADC) that converts the output of the filter section 6 into digital.
7, a central processing unit (hereinafter referred to as CPU) 8 connected to the ADC section 7, a memory 9 connected to the CPU 8, and an output section 10 connected to the CPU 8.

Next, the operation will be explained. The current of the power transmission line 1a passes through the current transformer 1, the transformer 2, and the filter section 6, and becomes a signal as shown in FIG. 3a.
The signal is input to the ADC 7, further converted into a digital signal by the ADC 7, and sequentially written to the data area of the memory 9 by the CPU 8 as data. On the other hand, the CPU 8 constantly executes a process of reading data in the data area of the memory 9 and determining whether an accident has occurred on the power transmission line 1a, according to the accident determination program stored in the memory 9. When it is determined that an accident has occurred, the operation output of the device is sent out from the output section 10.

When inspecting and monitoring the functions of the device, the contacts 3 are closed and a predetermined voltage is applied from the power source 4 to the winding 2b.
This voltage is passed through the windings 2b and 2c to the filter section 6.
The signal is applied as a signal, and as mentioned above, it becomes the data for determining the accident.

By the way, since the positive sequence current of the power transmission line is always at a certain level, it is possible to check whether the device is malfunctioning or malfunctioning. However, in a system with low zero-sequence voltage and power flow, inspection and monitoring to determine whether malfunctions or malfunctions occur due to positive-sequence current and zero-sequence current are difficult.
A power source for inspection and monitoring must be provided as shown in Figure 1. Then, by detecting that there is a constant output value even though there is no input during normal operation,
This enables inspection and monitoring of malfunctioning side.

As mentioned above, conventional devices require a separate power supply, contacts, etc. for inspection and monitoring, and the number of windings in the transformer increases, making the device large and having the disadvantage that inspections cannot be performed without operating the contacts. It was hot.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it provides a protective relay that allows inspection of the input circuit at all times by applying a bias voltage for inspection and monitoring at the filter section. The object of the present invention is to provide an inspection and monitoring device for an input circuit of a device.

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 2, the same symbols as in Fig. 1 indicate the same or corresponding parts, and from Fig. 1, contact 3 and power supply 4
A configuration is shown that eliminates the need for However, a bias voltage α(0) for inspection and monitoring at a predetermined level is applied to the filter unit 6.

Next, the operation will be explained. The current of the power transmission line 1a is input as a signal to the ADC 7 via the current transformer 1, the transformer 2, and the filter section 6, where it is converted into a digital signal and further written into the memory 9 as data. The CPU 8 reads out this data from the memory 9 and, in accordance with the program stored in the memory 9, determines whether an accident has occurred in the power transmission line 1a.

By the way, since the filter unit 6 superimposes the bias voltage α at a level that enables inspection and monitoring on the fundamental wave component β as shown in FIG. 3b, the CPU 8
Always calculate the bias voltage α of the filter section 6 from each data.
, and performs arithmetic processing to determine the existence of an accident with respect to the fundamental wave component β, and also performs arithmetic processing to determine the presence of an accident with respect to the fundamental wave component β. Conduct inspection and monitoring. In other words, the quality of the system input section is determined by determining whether the predetermined bias voltage α has been converted correctly using the output value of the ADC 7 via the filter section 6.

In the above embodiments, the arithmetic processing is performed digitally, but it may also be performed analogously.

As described above, according to the present invention, the system input section is inspected and monitored by applying a pre-existing bias voltage to the filter section. This eliminates the need for windings, etc., and allows for inspection without complicating the device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram explaining a conventional input circuit inspection device, FIG. 2 is a circuit diagram explaining an inspection device according to an embodiment of the present invention, and FIG. 3 is a circuit diagram explaining a conventional input circuit inspection device.
FIG. 3 is a waveform diagram illustrating the operation of the input circuit shown in the figure. 1... Current transformer, 2... Transformer, 6... Filter section, 7... ADC, 8... CPU, 9... Memory,
10...Output section. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A filter section that extracts a fundamental wave component from the electrical quantity of the system and superimposes an externally applied inspection bias voltage on the fundamental wave component, and an analog-to-digital conversion that digitally converts the output signal from the filter section. writing the data converted by the analog-to-digital converter into a memory and removing the bias voltage using the data read from the memory to perform an accident judgment process on the system, and perform an inspection/monitoring process based on the bias voltage. An inspection and monitoring device for the input circuit of a protective relay device, comprising a central processing unit that performs the following.