JP3263763B2 - Digital protection controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital protection and control device, and more particularly to a digital protection and control device which receives an AC signal from a power system to be controlled and performs control for protecting the power system based on the input signal. The present invention relates to a digital protection and control device suitable for automatically checking for an abnormality in an input system.

[0002]

2. Description of the Related Art In a power system, a breaker is arranged for each section to be monitored, a current in each section to be monitored is input via an auxiliary transformer, and a trip relay is provided when the input current indicates an abnormal value. Is driven to trip the circuit breaker. A digital protection control device is provided as a device for tripping the circuit breaker.
In this type of conventional digital protection control device,
An output signal of the auxiliary transformer is input to a microcomputer via an analog filter, a sample-and-hold circuit, a multiplexer, and an A / D converter, and the microcomputer determines whether or not the current value in the monitoring target section indicates an abnormal value. A configuration is employed. Furthermore, the digital protection controller has a self-diagnosis function as a constant monitoring function, and monitors whether or not the value of a signal obtained from the monitoring target section via the signal input system is always equal to or greater than a set value. When the level of the signal obtained from the signal input system falls below the set value, it is determined that the signal input system is abnormal. Furthermore, in order to reliably diagnose failures due to malfunctions in the signal input system, a method is adopted in which the signal input system is duplicated and the main relay and the fersafe relay are each controlled by a single microcomputer. Have been.

However, an active element is used in a signal input system, and when an active element fails, a signal accompanying a malfunction may not be generated. Cannot be determined.

Therefore, an automatic inspection system is adopted in which an inspection signal is forcibly input to an analog signal input system including an active element, and the presence or absence of an abnormality in the analog signal input system is determined based on the inspection signal. As this automatic inspection method,
For example, what is described in the section of automatic inspection of "Electric Joint Research Vol. 41, No. 4, digital relay" is known. In this automatic inspection method, a winding for inspection is added to the auxiliary transformer, and an inspection input is applied to this winding from an inspection power supply at the time of inspection, or the inspection winding is not provided in the auxiliary transformer. The check input is superimposed on the AC input obtained from the system by adopting any method of directly applying the check input to the secondary side of the auxiliary transformer, and the signal including the AC signal and the check input is converted into a digital signal. And an arithmetic processing unit compares the input data at the time of inspection with a predetermined value written in a program in advance to determine the quality of the analog signal input system.

[0005]

However, the prior art does not sufficiently consider that the protection function is interrupted at the time of the automatic inspection. It may not be possible to respond quickly. That is, at the time of automatic inspection, when an inspection signal is input to the analog signal input system, the AC signal obtained from the power system and the inspection signal are combined, and processing according to the combined signal is performed. Since the circuit breaker is tripped when the level of the combined signal reaches a level for driving the trip coil, a trip lock control for forcibly stopping the circuit breaker from tripping during inspection is employed.
For this reason, at the time of automatic inspection, the protection function for protecting the power system must be interrupted.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital protection and control device capable of automatically checking for an abnormality in an analog signal input system without interrupting a protection function for a controlled object.

[0007]

To achieve SUMMARY OF for the] said object, the present invention is an AC signal input means for inputting an AC signal from the control target of the electric power system, said power in response to the inspection command
Check signal generating means for generating a check signal of the fundamental frequency of the system, and adding means for adding an AC signal by an input of the AC signal input means and a check signal from the check signal generating means,
An analog filter for extracting a fundamental wave component from the output signal of the adding means, a sample and hold means for sequentially sampling the output signal of the analog filter at a specified timing and holding a signal obtained by the sampling, and an inspection signal generating means Analog-to-digital conversion means for converting a check signal from a digital signal into a digital signal, analog-to-digital conversion means for a composite signal for converting the output signal of the sample-and-hold means to a digital signal, and analog-to-digital conversion means for a check signal A deviation calculating means for calculating a deviation between the output signal of the analog signal and the output signal of the analog-to-digital conversion means for a composite signal, and a value calculated by the deviation calculating means and a first set value .
First control means for outputting a first control signal to the controlled object,
The output signals of the two analog-digital conversion means and the second
To the second control signal according to the comparison result.
A second control means for outputting a signal to a control target;
A digital protection control device comprising an analog signal abnormality determination means for monitoring a control signal and the second control signal to determine whether or not the analog signal system is abnormal. Things.

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

According to the above-mentioned means, when an inspection command is issued, an inspection signal is input to the analog signal input system. This check signal is combined with an AC signal obtained from the power system, the combined signal is sampled via an analog filter, and the sampled signal is sequentially converted into a digital signal. At this time, the inspection signal is also sequentially sampled at a designated timing and converted into a digital signal. Then, a deviation between a digital signal obtained from a signal including the AC signal and the inspection signal and a digital signal obtained only from the inspection signal is obtained. Since this deviation indicates the value of the AC signal itself in the power system, the deviation value does not exceed the set value except when the power system is abnormal, and the protection function for the control target is not interrupted and the analog signal input system is not interrupted. Can be determined. That is, by monitoring the digital signal obtained by the A / D conversion, it is possible to determine whether there is an abnormality in the analog signal input system.

[0015]

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

In FIG. 1, a digital protection control device includes auxiliary transformers T1 to Tn, adders A1 to An, analog filters F1 to Fn, and a sample and hold circuit SH0.
To SHn, a multiplexer 10, an A / D converter 12, an arithmetic processing unit 14, an inspection input control circuit 16, an inspection input power supply circuit 18, and a switch 20.

Each of the auxiliary knitting machines T1 to Tn is connected to a power system to be controlled, receives an AC signal from the power system, reduces the input AC voltage, and adds the circuits to the addition circuits A1 to An.
It is configured as an AC signal input means for outputting to an AC power supply. The addition circuits A1 to An input the AC signals from the auxiliary transformers T1 to Tn and also input the check signal from the check input power supply circuit 18, add the AC signal from the power system and the check signal, and add the signals. It is configured as an adding means for outputting a signal to the analog filters F1 to Fn. The analog filters F1 to Fn are configured as main analog filters that extract a fundamental wave component, for example, a signal of 50 Hz from the output signals of the addition circuits A1 to An, and output the extracted signals to the sample and hold circuits SH1 to SHn. . The sample-and-hold circuits SH1 to SHn include analog filters F1 to F1.
The Fn output signal is sequentially sampled at a designated timing, the signal obtained by the sampling is held, and the held signal is output to the multiplexer circuit 10 as main sample and hold means. The sample hold circuit SH0 takes in an inspection signal from the inspection input power supply circuit 18 via the switch 20, sequentially samples the inspection signal at a specified timing, and serves as an inspection sample and hold means for holding a signal obtained by sampling. It is configured. The multiplexer circuit 10 includes the sample hold circuits SH0 to SH0.
The signals from SHn are sequentially fetched, and the input signal is
The data is output to the D converter 12. The A / D converter 12 sequentially converts the signal from the multiplexer circuit 10 into a digital signal, and outputs the converted digital signal to the arithmetic processing unit 14. That is, the multiplexer circuit 10 and the A / D converter 12 are configured as analog / digital conversion means.

The arithmetic processing unit 14 is constituted by a microcomputer having a CPU, a memory, and the like, for example.
Keyboard, CR via input / output interface circuit
T, a trip coil drive circuit, and the like. The arithmetic processing unit 14 performs arithmetic processing according to the digital signal obtained from the A / D converter 12, and based on the calculated value, constantly monitors whether or not there is an abnormality in the analog signal input system. An automatic check function is provided to check whether there is any abnormality in the analog signal input system according to the check command. Further, the determination result according to the calculated value is displayed as an image on the screen of the CRT, and a control signal for driving the trip coil is output to the trip coil driving circuit. Further, when an automatic inspection is instructed by operating the keyboard, an inspection instruction is output to the inspection input control circuit 16. When a check command is input to the check input control circuit 16, the contact of the switch 20 closes,
A 50 Hz check signal is input from the check input power supply circuit 18 to the adder circuits A1 to An and to the sample and hold circuit SH0.

Next, the operation of the present embodiment will be described with reference to the flowchart of FIG.

The channel B of the analog signal input system
To N, the power flow I to the power system to which channel B is connected.
Description will be made assuming that L is flowing.

First, when the arithmetic processing section 14 is activated, it is determined whether or not the inspection has been activated (step 200).
That is, it is determined whether the automatic activation by the timer has started or the manual activation associated with the operation of the keyboard has started. Then, when the inspection start is not started, the return processing of the inspection input is executed (step 10).
2) When the inspection start is started, an inspection preparation process is executed (step 104). In this step 104,
A check is performed to determine whether or not a failure has occurred in the device, and a check is to be performed to determine whether or not the Felsafe relay has detected a system failure. Outputs an inspection command to the inspection input control circuit 16 (step 10).
6). When an inspection command is input to the inspection input control circuit 16, the contact of the switch 20 is closed according to a signal from the inspection input control circuit 16, and the addition circuits A1 to An and the sample hold circuit S
An inspection signal of 50 Hz is input to H0.

The check signal IT is a sample and hold circuit SH
0, when input to the A / D converter 12 via the multiplexer 10, the inspection signal IT is sequentially converted into a digital signal. This digital signal is subjected to a filtering process in the arithmetic processing unit 14 by a digital filter having the same characteristics as the analog filters F1 to Fn. Then, the current I (A) obtained from the channel A becomes ITF. (Step 108).

On the other hand, the addition circuit A1 of the channel P includes:
A power flow IL from the power system is input via the auxiliary transformer T1, and a check signal IT is input. When these signals are combined by the adder circuit A1, the combined signal is converted into an analog filter F1, a sample-and-hold circuit S1,
The signal is input to the A / D converter 12 via the multiplexer 10. When the composite signal including the power flow and the inspection signal is converted into a digital signal, the current I obtained from channel B
(B) becomes ILF + ITF (step 110).

Next, the current I obtained from the inspection signal alone
A deviation between (A) and the current I (B) obtained from the combined signal including the inspection signal and the power flow is calculated (step 112). This deviation ILF indicates the value of the power flow IL itself after passing through the filter. After calculating the power flow ILF, it is determined whether or not the inspection is being performed (step 114). If the inspection is not being performed, the process proceeds to step 122, and if the inspection is being performed, the process proceeds to step 116. Then, during the inspection, an automatic inspection process is performed on the channels A and B of the analog signal input system based on the calculated data of the currents I (A) and I (B) (step 116). That is, after the automatic inspection is started, the currents I (A) and I
When the value of (B) indicates a value larger than before the start of inspection, it can be determined that the analog signal systems of channels A and B are normal, and the values of currents I (A) and I (B) are automatically When the same value as before the start of inspection is shown, channels A and B
Can be determined to be abnormal in the analog signal input system. Then, based on the execution of the inspection processing, it is determined whether or not the apparatus is normal (step 118). When an abnormality of the apparatus is confirmed, a signal indicating the abnormality of the apparatus is output to CR.
A process for outputting to T or locking the relay output is executed (step 120).

On the other hand, if the device is normal, step 1
Based on the power flow ILF data obtained in step 12, a relay operation process is executed (step 122). That is, the tide ILF
Is performed to determine whether or not exceeds the set value.
When F exceeds the set value, a process of outputting a control signal for exciting the trip coil to the trip coil drive circuit is performed. If the power flow ILF does not reach the set value, the power system is determined to be normal and the process returns to step 100 again, executes the above-described process again, and ends the process of this routine.

As described above, according to the present embodiment, at the time of the automatic inspection, only the inspection signal is input to the channel A, and the inspection signal and the power flow are input to the channel B.
B is converted into a digital signal, and the power flow IL is calculated from the deviation between channel A and channel B.
Since F itself is calculated and the channels A and B are automatically checked according to the currents I (A) and I (B) obtained from each channel, the channels A and B are automatically checked without trip lock. Can be performed.

Also, as shown in FIG.
Is provided with an analog filter F0, the inspection signal IT can be obtained as ITF without performing a filtering process using a digital filter on the digital signal obtained from the channel A.

Further, in the above-described embodiment, the case where the 50 Hz AC signal is used as the inspection signal has been described.
It is also possible to use a DC signal as the inspection signal.

In the above embodiment, channels B to
If the channel N is made a dual system, the signals obtained from the respective systems are compared with each other, and the inspection processing is executed based on the comparison result, it is possible to more accurately determine the abnormality of the analog signal input system.

In the above embodiment, when the control signal is output to the trip coil drive circuit based on the power flow ILF, the control signal can be corrected in consideration of the inspection results of the channels A and B. By executing such a correction process, it is possible to prevent the tidal current ILF from displaying an abnormal value due to the automatic inspection and erroneously exciting the trip coil.

[0031]

As described above, according to the present invention ,
Inspection without interrupting the protection function for the controlled object
Inspection signal generation means for generating power input
It is possible to automatically determine whether there is an abnormality in the analog signal system in the fundamental frequency band .

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital protection and control device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the device shown in FIG.

FIG. 3 is a block diagram of a digital protection and control device according to another embodiment of the present invention.

[Explanation of symbols]

 T1 to Tn Auxiliary transformer A1 to An Adder circuit F0 to Fn Analog filter SH0 to SHn Sample hold circuit 10 Multiplexer circuit 12 A / D converter 14 Operation processing unit 16 Inspection input control circuit 18 Inspection input power supply circuit 20 Switch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-150017 (JP, A) JP-A-61-128717 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02H 3/05

Claims (1)

(57) [Claims] 1. A an AC signal input means for inputting an AC signal from the control target of the electric power system, said power in response to the inspection command
Check signal generating means for generating a check signal of the fundamental frequency of the system, and adding means for adding an AC signal by an input of the AC signal input means and a check signal from the check signal generating means,
An analog filter for extracting a fundamental wave component from the output signal of the adding means, a sample and hold means for sequentially sampling the output signal of the analog filter at a specified timing and holding a signal obtained by the sampling, and an inspection signal generating means Analog-to-digital conversion means for converting a check signal from a digital signal into a digital signal, analog-to-digital conversion means for a composite signal for converting the output signal of the sample-and-hold means to a digital signal, and analog-to-digital conversion means for a check signal A deviation calculating means for calculating a deviation between the output signal of the analog signal and the output signal of the analog-to-digital conversion means for a composite signal, and a value calculated by the deviation calculating means and a first set value .
First control means for outputting a first control signal to the controlled object,
The output signals of the two analog-digital conversion means and the second
To the second control signal according to the comparison result.
A second control means for outputting a signal to a control target;
A digital protection control device comprising: an analog signal abnormality determination unit that monitors a control signal and the second control signal to determine whether or not the analog signal system is abnormal.