JP3727802B2 - Protective relay device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a protective relay device, and more particularly, to a protective relay device for monitoring an analog input and protecting a power system in a digital relay used for power system protection.
[0002]
[Prior art]
A digital relay that detects an accident that occurs in the power system by inputting the current amount of the power system, converting the input analog amount into a digital value, and performing arithmetic processing to detect an accident that occurs in the power system. Is used.
[0003]
Such a digital relay will be described with reference to the block diagram of FIG.
The electric power system current is taken in as an analog quantity by the ammeter 2 and input to the input conversion means 2 of the digital relay 1. The input analog quantity is input to an analog input means 3 including a filter circuit 4, a sampling hold circuit 5, a multiplexer 6, and an analog / digital conversion circuit 7. In the filter circuit 4, after filtering, the data is held in the sampling hold circuit 5, and the sampling data is sequentially output to the analog / digital conversion circuit 7 in time series by the multiplexer 6. The input analog quantity is converted into a digital quantity by the analog / digital conversion circuit 7, and this digital quantity is read by the relay computing element 8 to perform the relay computing process. When the relay operates, the sequence processing element 9 performs the sequence processing. The output processing means 10 outputs a trip signal 11 and trips the circuit breaker to protect the power system.
[0004]
A detailed view of the above-described conventional input conversion means is shown in FIG.
In the figure, the current of the electric power system is double-inputted from two channels to the input converter 2 of the digital relay 1 as an analog input monitoring means by an ammeter as the input conversion means 2. The absolute value | I ₁ −I ₂ | of the difference between these two analog input quantities I ₁ and I ₂ is expressed by the expression | I ₁ −I ₂ | ≧ α (where α is a positive real number and generally 10% of the rating) The analog input of the digital relay is monitored and the power system is protected using the current amount I ₁ .
[0005]
In addition, the digital relay is guaranteed to have an overcurrent strength that can withstand a current that is 40 times the rated current for one second, but in the conventional digital relay configuration, the CT secondary current flows twice. There was a possibility that an accident current that could not be tolerated by the current intensity would flow.
[0006]
[Problems to be solved by the invention]
On the other hand, in the conventional digital relay input conversion means, the current transformer secondary circuit is wired in series with the two channels as the analog input monitoring means, so that the current transformer secondary circuit is disconnected. , The amount of current can not be extracted from both. Therefore, it is impossible to detect a failure of the analog input, and it is impossible to protect the power system.
[0007]
The present invention (corresponding to claims 1 to 4) has been made in view of the above situation, and its purpose is to wire a current transformer secondary circuit in parallel so that a circuit such as disconnection can be obtained. An object of the present invention is to provide a protective relay device that enables analog input monitoring and power system protection in other circuits even if an accident occurs.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 of the present invention provides a current amount capturing means for capturing a current amount of a power system, an input converting means for inputting the captured analog amount, and converting the analog amount into a digital amount. An analog / digital conversion means for converting, a relay calculation means for operating the relay according to the digital quantity, a sequence processing means for performing a sequence process by the relay operation, and an output processing means for performing an output process by the sequence process In the protective relay device, a plurality of input conversion means connected in parallel on the secondary side of the current amount taking-in means, and each analog current value detected by each of the input conversion means or each analog An analog input monitoring unit for determining whether or not the ratio of the current amounts is a predetermined value is provided.
[0009]
According to a second aspect of the present invention, in the protective relay device according to the first aspect, the impedance ratio of two or more input conversion means is automatically calculated and used for automatic matching of analog input monitoring. To do.
[0010]
According to a third aspect of the present invention, in the protective relay device according to the first aspect, the relay calculation is performed by the sum of the analog current amounts detected by the two or more input conversion means.
[0011]
According to a fourth aspect of the present invention, in the protection relay device according to the first aspect, the secondary of the current amount capturing means is provided by a plurality of input conversion means connected in parallel on the secondary side of the current amount capturing means. It is characterized by increasing the overcurrent strength of the circuit.
According to claims 1 to 4, even if an accident such as disconnection occurs in the secondary circuit of the current transformer, it is possible to monitor the analog input and protect the power system, and to connect the secondary side of the current transformer. Since it is parallel, the overcurrent strength of the digital relay can be increased, and a highly reliable protection device can be provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of an embodiment of the present invention (corresponding to claim 1). The configurations different from the conventional example already described in this embodiment are an input conversion means and a current ratio calculation means of a digital relay.
[0013]
As shown in the figure, the input conversion means 2 of the digital relay 1 which is the protective relay device of this embodiment has two input converters connected in parallel to the secondary circuit of the current transformer. Reference numeral 12 denotes current ratio calculation means, which calculates the secondary current ratio K.
[0014]
Next, the operation of this embodiment will be described.
The analog current amount of the power system is input to the input converter means 2 having a parallel input converter. If the secondary current ratio of the current transformer during normal operation is K = I ₂ / I ₁ , it becomes | I ₁ −KI ₁ | = 0. When an unbalance occurs and | I ₁ −KI ₁ | becomes greater than or equal to α, an analog input monitoring failure is detected. Here, K is calculated by initial test adjustment using the current ratio calculation means 12.
[0015]
In this embodiment (corresponding to claims 2 to 4), even if a disconnection failure occurs in one input converter, if the other input converter is normal, the secondary circuit of the current transformer It is possible to protect the power system by using the sum of the input current amounts of the respective input converters. Furthermore, the impedance ratio of two or more input conversion means is automatically calculated, and analog input monitoring is performed. A highly reliable protective relay device can be provided by using it for automatic matching or by increasing the overcurrent strength of the secondary circuit of the current amount capturing means.
[0016]
【The invention's effect】
As described above, according to the present invention (corresponding to claims 1 to 4), analog input monitoring and power system protection are possible even when an accident such as disconnection occurs in the secondary circuit of the current transformer. In addition, since the secondary side of the current transformer is arranged in parallel, the overcurrent strength of the digital relay can be increased, and a highly reliable protective relay device can be provided.
[Brief description of the drawings]
FIG. 1 is a detailed diagram of input conversion means of a digital relay that is an embodiment of the present invention.
FIG. 2 is a processing configuration diagram of a conventional digital relay.
FIG. 3 is a detailed diagram of input conversion means of a conventional digital relay.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Digital relay, 2 ... Input conversion means, 3 ... Analog input means, 4 ... Filter circuit, 5 ... Sampling hold circuit, 6 ... Multiplexer, 7 ... Analog / digital conversion circuit, 8 ... Relay operation means, 9 ... Sequence processing Means, 10 ... output processing means, 11 ... trip output, 12 ... current ratio calculation means.

Claims (4)

  Current amount capturing means for capturing the current amount of the power system, input conversion means for inputting the captured analog amount, analog / digital conversion means for converting the analog amount to a digital amount, and the relay is operated by the digital amount In a protective relay device comprising: a relay computing means to be operated; a sequence processing means for performing a sequence process by a relay operation; and an output processing means for performing an output process by this sequence process. A plurality of input conversion means connected in parallel, and each analog current amount value detected by each of the input conversion means or a ratio of each analog current amount is determined to be a predetermined value. A protective relay device comprising analog input monitoring means.   2. The protective relay device according to claim 1, wherein the impedance ratio of two or more input conversion means is automatically calculated and used for automatic matching of analog input monitoring.   2. The protective relay device according to claim 1, wherein a relay operation is performed based on a sum of analog current amounts detected by two or more input conversion means. 2. The protective relay device according to claim 1, wherein the overcurrent intensity of the secondary circuit of the current amount capturing means is increased by a plurality of input conversion means connected in parallel to the secondary side of the current amount capturing means. A protective relay device characterized by that.

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