JPS6390450A - Digital protecting relay device for d.c. power feed line - Google Patents

Abstract

PURPOSE:To make it possible to surely discriminate trouble current during start of an electric car, by detecting the presence of a trouble in such a logic AND that whether or not the degree of load current through a d.c. power feed line, which is subjected to A/D conversion, exceeds a predetermined value or not, and whether or not an increasing variation in the current is continued for a predetermined time. CONSTITUTION:A digital relay section 16 is composed of a d.c. power feed line load current input section 11, an A/D converting section 12, a CPU section 13 and a memory section 14, and digitally processes d.c. power feed line load current so that the presence of a trouble is discriminated in accordance with such a logic AND condition that whether or not the degree of load current exceeds a predetermined value, and whether or not a variation in the load current exceeding a predetermined value is continued for a predetermined time. With this arrangement, it is possible to surely discriminate whether it is a load current or a trouble current during start of an electric car, and therefore it is possible to eliminate unnecessary operation, thereby it is possible to make highly sensible and accurate detection and protection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital protection relay device for DC feeder lines.

[Conventional technology]

Conventionally, there have been devices of this type that are listed in the fifth factor. In the figure, (3) is an integrating circuit, (4) is a level detection circuit, and (5) is an output circuit section to the outside.

Next, the operation will be explained. In the integrating circuit (3),
The input is integrated, the input is smoothed, and the level is detected by the primary level detection circuit (4). If there is an input change above a certain level, this novel detection circuit (4) outputs an output signal to a circuit output section (5), and outputs an output signal from this output section (5) to an external circuit (2).

[Problem that the invention seeks to solve]

The conventional device is configured as described above.

It is necessary to set the level detection value to be greater than the load flow change level, which has the drawback of not being able to provide highly sensitive and highly accurate protection.

In order to eliminate the drawbacks of the conventional devices as described above, this invention detects a failure using the AND condition of the level detection condition and the condition that the current increase change of more than a certain value continues for a certain period of time. By doing so, it is an object of the present invention to provide a DC line digital protective relay device that can detect failures with high sensitivity and high accuracy.

[Means for solving problems]

The DC tan digital protection relay device according to the present invention is set to detect a level of a current value, detects a value equal to or higher than the level, and is further conditioned to continue for a certain period of time or more with an increase change of more than a certain value. The logical product (AND) of two different conditions in F is calculated to determine a failure.

[Effect]

The detection method used in this invention enables highly accurate detection by detecting the level using the input VL as it is, and detects that an increasing change of more than a certain value continues for a certain period of time. This makes it possible to distinguish between the train load current and fault current. Further, by making a final judgment using the AND results of different judgment methods, accurate failure judgment is possible, and detection between detection paths is also performed with high sensitivity.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 3 1, C1) is a direct current! The load current waveform of the rope is shown. In Fig. 4, (2) shows the fault current waveform of the DC-feeding fi line. In FIG. C4 is a memory section that stores programs.

(to) is an input/output section, and the DC TTS digital protection relay device of the present invention, that is, the digital relay o0 is constituted by the respective sections shown above. FIG. 2 is a block diagram showing a failure determination method.

As shown in Figure 3, the load current of the DC feeder wire changes as shown in the waveform (13) when switching from series to parallel and notch switching occurs when the car is started. .

Also, as shown in Figure 1, even at fault current (2
) changes as follows. Increase in train load I and accompanying load'at
i also increases, and there is no difference in magnitude between the fault current and the load current, and conversely, there are cases where the load current increases more than the fault current S. Therefore, the digital relay alS shown in Figure @1 is used to determine the load current and fault current. The input section αυ converts the DC feeder current to a semiconductor level and introduces it to the primary A/D conversion section (2). The A/D converter @ converts the analog input into digital data, and the CPU f15U performs digital calculations. After the above calculation, the CPU unit 0 executes digital calculation and system fault determination in accordance with the program f in the memory unit α which stores the program. Above CPU
The input/output section (G) connected to sa3 is a digital IJL/
- (16 input/output signal interface section,
Outputs an output signal to the outside when a system fault occurs or when making a determination.

Normally, the load current rises to a constant value due to series and parallel start-up and notch switching when starting the train, and forms a staircase waveform, as shown in Figure 11).

This load current passes through the human power unit 0υ, is converted into a digital value by the A/D converter @, and is digitally calculated by the CPUgC13 to calculate the magnitude of the load current.

This calculation data is stored in the memory section α4, and the current value at the time of the next parallel startup and non-chip switching is similarly digitally calculated to calculate the magnitude of the load current. The negative fault current characteristic is different from the load current characteristic at startup, and there is no stepwise change in which the rise of the scale E takes a constant value. Regarding the faulty current, digital relay a0 performs the same digital calculation as above to calculate the magnitude of the current. After Calculation@2 As shown in Figure 2, there are two conditions: the judgment condition that the magnitude of the current calculated by the above digital calculation is greater than or equal to a certain value, and the judgment condition that the current increase change greater than or equal to the certain value can continue for a certain period of time. Faults in DC feeder lines are determined using the AND condition (logical product). That is, determination of a system fault is carried out under the AND condition in which the current value is a certain value or more and the current increase change in which the force 1 is also a certain value or more continues for a certain period of time.

Further, in the above embodiment, the case of a digital relay has been described, but the same effect can be achieved with an analog relay.

In addition, the same effect can be obtained by performing a level determination in an analog section and performing an AND condition of the resultant signal and a condition in which the input power increaser 11 changes by a certain value or more in g series.

〔Effect of the invention〕

As described above, according to the present invention, the load current and the fault current can be clearly distinguished (as the structure is configured so that they can be distinguished clearly, unnecessary operations are eliminated, and highly sensitive settling sequence detection is possible, which improves reliability. This has the effect of providing a high-quality DC feeder digital protection relay device.

[Brief explanation of the drawing]

'@ Figure 1 is a block diagram showing a cloudy DC power t-line protection relay device according to an embodiment of the present invention, @ Figure 2 is a block diagram showing the system fault determination method in Figure 1, and Figure @ 3 is a block diagram showing the method for determining a system fault in Figure 1. A waveform diagram showing the load current waveform, Fig. 4 is a waveform diagram showing the normal fault current waveform, and Fig. 5 is a waveform diagram showing the conventional fault current waveform. FIG. 2 is a configuration diagram of a line protection relay device. In the figure, (1)...Load current waveform, 12+...
Fault current e, shape, 13)...Integrator circuit section, (4)...
・Level detection circuit section. (5)...Output circuit section, 0υ...Human power section, (6)・
...A/D conversion section, α]...CPUm2''...Memory section, (G) is input/output section, α0...Digital link part. f, f j3, same symbols in the figure are the same, or a corresponding portion.

Claims (1)

[Claims] In the protective relay device for DC feeding lines, an analog/
A digital converter calculates the load current digitally converted by the analog/digital converter, and determines the conditions for determining whether the magnitude of the load current is equal to or greater than a predetermined value and whether the current increase change exceeds a predetermined value. 1. A digital protection relay device for a DC feeder line, comprising: a central control unit section that outputs an AND result of the two conditions under the condition that the relay continues for a certain period of time to an input/output section.