JPH02237422A - Dc current relay device - Google Patents

Abstract

PURPOSE:To detect an accident correctly by setting a DC current a base current when the rate of change of the DC current exceeds a set value specified times in succession, and by opening a circuit breaker when the difference between the DC current and base current after that exceeds the predetermined value specified times in succession. CONSTITUTION:A CPU 24 reads a DC current value I of the primary circuit 21 through an input device in a constant cycle and calculates an increment I from the last read value. By deciding whether or not this increment value I exceeds a set value, and if it does so specified times in succession, then the current value will be set as a base current. After that, by judging whether or not the difference between a DC current value and a base current value exceeds the set value, and if it does so specified times in succession then a DC circuit breaker 20 will be opened through an output device 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direct current relay device for protecting a direct current circuit such as a feeder circuit of a direct current electric railway.

[Conventional technology]

For example, Figure 4 is published by the Railway Electrification Association, Electric Railway VOIr3
0, A6, Page 21
1) is the primary circuit, (2) is the unsaturated current transformer, (3) is the integrator circuit connected to the secondary side of the unsaturated current transformer (2), and (4) is the integrator circuit (3). This is a signal processing circuit connected to the output side.

Next, the operation will be explained. When current flows through the primary circuit (1) passed through it, the unsaturated current transformer (2) outputs the differential value of the primary current to its secondary side and calculates the change in the primary current. put out. The current differentiated by this current transformer (2) is input to an integrating circuit (3) which has a time constant considerably larger than that of this current transformer (2) and is integrated, resulting in changes in the primary current. A similar waveform is extracted.0 This similar waveform signal is input to a signal processing circuit (4), and if it becomes larger than a set level, it is determined that there has been an accident in the feeding circuit. By the way, in the feeding circuit of a DC electric railway, when a short circuit accident occurs, it not only detects fault current in a small current range that cannot be detected and cut off by a high-speed breaker, but also detects unnecessary load current such as train operating current. A DC current relay device that does not operate but can reliably detect fault current is required. In addition, it is desired that the setting value of the DC current relay device be as low as possible within a range that does not cause unnecessary operation due to the load K. It is necessary to detect fault current in the current range.

[Problem to be solved by the invention]

Conventional DC current relay devices are configured as described above, so the primary current is differentiated using a specially constructed unsaturated current transformer, a similar waveform is created using an integrating circuit (3), and the The signal needed to be processed. Therefore, the signal processing circuit (4) cannot use the primary current itself, and therefore cannot detect fault current quickly and at high speed, which is a limitation in improving protection performance.
Since an unsaturated current transformer (2) and an integrating circuit (3) are required, there are problems in that the device becomes expensive.

This invention was made in order to solve the above-mentioned problems, and the purpose is to obtain a DC current relay device that can improve detection sensitivity and lower the setting value than before. [Means for Solving the Problems] A direct current relay device according to the present invention takes in the direct current of a direct current circuit into an input device, and processes the taken in direct current according to a program stored in a storage device. , When the rate of change of the DC current exceeds the set value, the increment of the DC current from the point when the rate of change changes to the positive side is calculated using a microblower, and when this increment value exceeds the set value. The structure is such that an opening command is output to the DC breaker when the DC breaker is opened.

[Effect]

The microprocessor of the present invention determines whether the rate of change of the DC current is equal to or higher than a set value M times in a row;
If the current is greater than or equal to the set value, the DC current at the time when the rate of change changes to the positive side is the bottom current, and the increment of current is calculated from the difference from the DC current, and this increment value is set to the set value N times in a row. Determine whether or not the set value has been exceeded, and if the set value has been exceeded,
Does the output device issue an open command to the DC breaker? It works.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (to) is a DC circuit, which is a DC circuit. The primary circuit of a normal current transformer connected to the line is DC.
(c) is an input device for inputting the above input signal to the microprocessor (described later); c) is a microprocessor (central processing unit ff), fi is a storage device that stores a processing program for processing the control program program data that controls this equipment, and 2 is a case in which the data is processed and determined to be a fault current. This is an output device for sending the opening control output to the DC breaker ω.

Figure 2 is a characteristic diagram used to explain the following operation, and it shows the feeder line current of a DC railway substation over time on a coordinate system with current value on the vertical axis and time on the horizontal axis. This is shown in . Here, 31) is the operating current of the Chotupa control train, ■■■ is the operating current of the Kago control train, and (to) is the fault current. It shows the increment value of the current from the point when the differential value of Δ■ applied current 1 suddenly changes to the positive side, and if Δ■ exceeds the set value b, it is determined that there is no accident, and the operating current and fault current are distinguished. This is what I am trying to do.

Next, the operation will be explained according to the flowchart shown in FIG. First, the entire system is initially reset (step 50), and then, in order to calculate the increment Δ■ of the DC current 1, the DC current 1 is read in as an actual measurement value via the current transformer 1 at regular intervals (Step 51). . Note that this increment ΔI refers to the current increment from the point in time when the differential value of the current 1 changes to the positive side.

Then, the increment Δ! It is determined whether the current 1, which is a condition for the calculation of , is greater than 0 (i>o) (step 52), and if it is a dog, the rate of change of the current 1 (li/(Lt) is determined (step 53). Then, it is determined whether this rate of change di/at exceeds the set value l (step 54), and further, it is determined whether this rate of change di/at has exceeded the set value l (step 54).
A), if so, perform the cent of the bottom current (step 5
5), Is the current set from 1 here? Calculate the increment Δ■ by subtracting the current (step r: r6).
It is determined whether this increment Δ■ is υ larger than a predetermined set value 2 (step 57), and it is further determined whether this is continuous N times (step 57A), and in that case, the DC breaker An open command is issued (step 63), then the increment ΔI is reset (step 62), and the operations from step 51 are repeated again.

On the other hand, if the increment Δ■ is smaller than or equal to the set value 2 in step 5, or if it is not consecutive N times, the DC current is read (step 58), and then the rate of change di/(Lt (step 59), and determine whether this rate of change a ya t is greater than O (at, 4t) O)
is determined (step 60). As a result, if the change rate (l i/d If so, the increment Δ■ is reset (step 62), and the processes from step 51 onwards are repeated.

Although the above embodiment uses a microprocessor, a signal processing device capable of digital processing or analog processing may be used, and the same effects as in the above embodiment can be obtained. In addition, in the above embodiment, the case where ΔI current is detected to distinguish between fault current and operating current has been described, but it is also possible to use it for other purposes such as a failure point locating device or a high resistance ground fault detection device. .

〔Effect of the invention〕

As described above, according to the present invention, the DC current relay device differentiates the secondary current taken in from the current transformer to find the rate of change of the secondary current, and this rate of change remains at the set value 1 once in a row. If the increment of the secondary current exceeds the set value 2, it is determined whether or not the increment of the secondary current exceeds the set value 2. If it exceeds the set value N times in a row, it is determined that a fault current is flowing and the DC breaker is commanded to open. Since it is configured to emit K, a fault current can be detected quickly and reliably, and the fault current can be removed at an early stage, and the setting value can be lowered compared to the conventional one.

Further, even if there is noise in the DC current taken into the DC current relay device, there is an effect that rounding errors that are caused by multiple consecutive determinations can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block connection diagram showing a DC current relay device according to an embodiment of the present invention, FIG. 2 is a characteristic diagram explaining the operation of the DC current relay device, and FIG. 3 is a flow diagram explaining the operation. , FIG. 4 is a block connection diagram of a conventional DC current relay device. In the figure, ■ is a DC breaker, (to) is a primary circuit, is a current transformer, υ is an input device, @ is a microprocessor (central processing unit I!), (a) is a storage device, ? Q is an output device. In addition, in the figures, the same reference numerals indicate the same or corresponding parts 0 Figure 1 2111;

Claims (1)

[Claims] an input device that takes in the DC current of the DC circuit; a storage device that stores a program for processing the DC current that is taken in by the input device; , the DC current at the point when this exceeds the bottom current is defined as the bottom current, and the microprocessor calculates the current increment from the difference between the DC current and the bottom current, and the current increment value calculated by this calculation exceeds the set value a predetermined number of times in a row. A direct current relay device equipped with an output device that outputs an open command to a direct current or disconnector when