JP5351744B2 - Digital protection control device and health monitoring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital protection control unit continuously monitoring the soundness of a signal cable that relays analog signal between an input unit and a control unit. <P>SOLUTION: The input unit transmits the analog signal and a connection state signal, representing the soundness of the signal cable to the control unit; the control unit uses the same A/D converter for input of a reference signal supplied from the outside at adjustment work, and inputting of the connection state signal after completion of calculation of the correction parameter, namely, in an actual operation, to calculate correction parameters corresponding to input characteristics of the analog signal. As a result, continuous monitoring of the soundness of the signal cable becomes available, without having to add special circuits. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a digital protection control device, and more particularly to a digital protection control device suitable for monitoring the soundness of a signal cable that relays an output from an input transformer that measures the amount of electricity in a power system. .

In a digital protection control device used for power system protection control, an input unit for taking in an output from an input transformer that measures the voltage and current of the power system, and protection control calculation by executing protection control calculation The control unit for performing the measurement is configured as a separate unit, and the analog signal of the measurement result is relayed through a signal cable connecting between them.
The analog signal representing the amount of electricity of the power system input via the input transformer cannot determine the soundness of the signal cable only by the presence / absence of the input signal because the state of the signal in the steady state is not determined. Therefore, in the conventional digital protection control device, the soundness of the signal cable that relays the analog signal in the device is not always monitored. As a result, abnormalities such as signal cable dropouts and disconnections can only be detected during regular inspections, and protection control operations may not function correctly due to signal cable abnormalities when a system fault occurs. There was concern.

As a conventional technique for monitoring the soundness of a signal cable, Patent Document 1 is connected by adding a signal line for transmitting a connection state monitoring signal (for example, a reference voltage signal) to the signal cable. A technique for detecting a connection state monitoring signal output from one of the two units with the other unit is disclosed.
Further, in Patent Document 2, a circuit for superimposing a predetermined inspection signal on an analog signal output from the input unit of the digital protection control device is added, and the superimposed inspection signal is digitally processed by the control unit. And a technique for detecting an abnormality in an analog input system in the apparatus.

JP-A-4-116473 JP-A-6-105445

  However, the technique disclosed in Patent Document 1 has a disadvantage that it is necessary to add a dedicated circuit for detecting a connection state monitoring signal to the control unit. In addition, the technique disclosed in Patent Document 2 requires that a dedicated circuit for superimposing an inspection signal is added to the input unit, resulting in inconvenience that the circuit of the input unit becomes complicated.

  The present invention has been made to solve the above-described disadvantages, and provides a digital protection control device that can constantly monitor the soundness of a signal cable that relays an analog signal between an input unit and a control unit. The task is to do.

The present invention for solving the above-described problems includes an input unit having a plurality of channels for inputting an analog output signal from an input transformer for measuring an electric quantity of a power system and outputting an analog signal obtained by converting a signal level. A control unit that converts the analog signal output from the input unit into a digital signal, inputs the digital signal, and executes a predetermined protection control operation based on the digital signal to perform protection control of the power system. In the digital protection control apparatus connected by a detachable signal cable that transmits a signal, the signal cable includes a signal line that transmits the analog signal, a signal line that transmits a connection state signal output from the input unit, and A connector that fits into a connector included in the control unit, and the control unit is configured to adjust the input unit from a reference signal supply unit during an adjustment operation. An input reference signal supplied without being and an input of the connection status signal is performed using the same A / D and used to input the analog signals (Analog / Digital) converter,
During the adjustment work, the reference signal supplied from the reference signal supply unit without passing through the input unit, and the reference signal supply unit input as the analog signal through the input unit and the signal cable. By comparing with a reference signal, a correction parameter for correcting the analog signal input thereafter is calculated, and after the calculation of the correction parameter is completed, the connection state signal is input to input the signal cable. Monitor health ,
The reference signal and the connection state signal are input from the same input terminal of the connector included in the control unit .

  ADVANTAGE OF THE INVENTION According to this invention, the digital protection control apparatus which can always monitor the soundness of the signal cable which relays an analog signal between an input part and a control part can be provided.

It is a functional block diagram which shows the structure and signal flow of the main control part which concern on 1st Embodiment. It is a functional block diagram which shows the structure of the input conversion part which concerns on 1st Embodiment, and the flow of a signal. It is explanatory drawing which shows the connection structure at the time of an input characteristic measurement, and the flow of a signal. It is explanatory drawing which shows the connection structure after completion of an input characteristic measurement, and the flow of a signal. It is a functional block diagram which shows the structure and signal flow of the input conversion part which concern on 2nd Embodiment. It is explanatory drawing about the connection to the main control part by the conversion connector which concerns on 3rd Embodiment. It is a functional block diagram which shows the structure and signal flow of the main control part which concern on 4th Embodiment. It is a flowchart which shows operation | movement of a digital protection control apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

<First Embodiment>
First, the digital protection control apparatus according to the first embodiment of the present invention will be described with reference to FIGS. In the following drawings, the description of the output system of the protection control signal is omitted.

  FIG. 4 is an explanatory diagram showing a connection configuration and a signal flow when the measurement of input characteristics is completed and the apparatus enters actual operation. As shown in FIG. 4, the digital protection control device S is output from a main transformer 1 that is an input transformer that measures the amount of electricity such as voltage and current of a power system that is subject to protection control. An analog signal indicating the amount of electricity is converted into a digital signal, and the occurrence of a system fault is detected by program control, and a protection control relay (not shown) or a circuit breaker is activated to perform protection control of the power system. .

  At this time, the analog signal of a plurality of channels output from the main transformer 1 is converted in signal level by the insulating transformer 22 in the input conversion unit 2 and transmitted to the main control unit 4 through the signal cable 3, and then filtered. 42, the signal is input to the A / D converter 44 via the multiplexer 43 and converted into a digital signal. Therefore, the analog signal input to the A / D converter 44 has an offset error, a gain error, and a phase error depending on the characteristics of the transmission path of each channel from the main transformer 1 to the A / D converter 44. Occur. Therefore, in order to correct these errors, adjustment work is performed to measure the input characteristics of the analog signal using the reference signal and calculate the correction parameter prior to actual operation of the apparatus.

  FIG. 3 is an explanatory diagram showing the connection configuration and signal flow when measuring the input characteristics of an analog signal prior to actual operation of the apparatus. As shown in FIG. 3, at the time of measuring this input characteristic, a high-precision reference signal is generated by a high-precision oscillator 11 as a reference signal supply unit of the present invention, and is amplified by a precision amplifier 12 to be amplified by the main transformer 1. To the main control unit 4, the signal from the main transformer 1 through the transmission path is compared with the original reference signal by the main control unit 4 through digital processing. The

  Conventionally, the input terminal 41b for directly supplying the reference signal to the main controller 4 has not been used after the measurement of the input characteristics is completed. In the present embodiment, as shown in FIG. 4, the circuit of the main control unit 4 is supplied by supplying a signal indicating the soundness of the cable connection to the input terminal 41b after the measurement of the input characteristics is completed, that is, when the apparatus is actually operated. It makes it possible to monitor the soundness of the signal cable without changing the configuration.

  Next, the configuration and signal flow of the input conversion unit 2 as the input unit of the present invention will be described with reference to FIG. As shown in FIG. 2, the input conversion unit 2 includes a signal generator 21, n insulating transformers 22, and a connector 23. The n analog output signals output from the main transformer 1 are electrically isolated and converted in signal level by the corresponding isolation transformers 22, and analog signals 1 to n are output to the output terminals 23 a of the connector 23. Is output as

  The signal generator 21 supplies a connection state signal which is a signal indicating that the signal cable 3 connecting the input conversion unit 2 and the main control unit 4 is healthy, and this connection state signal is output from the connector 23. It is output to the terminal 23b. As the connection state signal, a DC or AC voltage signal or current signal, a clock signal, or an electric communication signal or an optical communication signal according to a predetermined protocol may be used as long as it can be detected by the main control unit 4. May be used.

  Each signal output to the output terminals 23 a and 23 b of the connector 23 is transmitted to the main control unit 4 by a multi-core signal cable 3 having a connector (not shown) fitted to the connector 23 at the end. As shown in FIG. 3, since the connection state signal need not be transmitted when measuring the input characteristics, it is preferable to use the signal cable 3a for measuring the input characteristics without the signal transmission line.

  Next, the configuration and signal flow of the main control unit 4 as the control unit of the present invention will be described with reference to FIG. As shown in FIG. 1, the main control unit 4 includes a connector 41, n filters 42, a multiplexer 43, an A / D converter 44, and a CPU (Central Processing Unit).

  The connector 41 receives n input terminals 41a for inputting n analog signals 1 to n transmitted from the input conversion unit 2, and a reference signal supplied from the high-precision oscillator 11 when measuring input characteristics. After completion of input characteristic measurement (after completion of correction parameter calculation), an input terminal 41b for inputting a connection state signal transmitted from the input conversion unit is provided.

  As shown in FIG. 3, at the time of input characteristic measurement, each input terminal 41a has a measurement result corresponding to a signal supplied from the high precision oscillator 11 to the main transformer 1 via the precision amplifier 12 and amplified from the reference signal. An analog signal is transmitted from the input conversion unit 2 by a signal cable 3a for measuring input characteristics. Further, as shown in FIG. 4, after the input characteristic measurement is completed (after correction parameter calculation is completed), that is, when the apparatus is actually operated, each input terminal 41a represents the electric quantity of the power system measured by the main transformer 1. An analog signal is transmitted from the input conversion unit 2 by the signal cable 3 together with the connection state signal. The signal cable 3 has a connector (not shown) that fits into the connector 41 at the end, thereby connecting the connection state signal between the input conversion unit 2 and the main control unit 4 and the analog signals 1 to n. Transmission paths can be established simultaneously.

  Each analog signal 1 to n input to the input terminal 41a is transmitted to the corresponding filter 42, and after the analog filter processing for removing the noise by the specific frequency component and preventing the aliasing error by sampling is performed, the multiplexer 43 Is transmitted. Further, the reference signal or connection state signal input to the input terminal 41 b is directly transmitted to the multiplexer 43.

  The multiplexer 43 generates a time division multiplexed signal in which a plurality of signals transmitted from the input terminal 41 b and the filter 42 are sequentially selected at a predetermined cycle, and transmits the time division multiplexed signal to the A / D converter 44. The A / D converter 44 samples the time division multiplexed signal transmitted from the multiplexer 43 at a predetermined frequency, converts the analog signal into a digital signal, and transmits the converted digital signal to the CPU 45. The CPU 45 inputs a value of each signal input from each input terminal 41a, 41b of the connector 41 as a digital value sequence sampled at a predetermined frequency by executing a predetermined program.

  Thereafter, the CPU 45 calculates a correction parameter corresponding to each of the analog signals 1 to n by executing a correction parameter calculation process at the time of input characteristic measurement, and after the input characteristic measurement is completed (after the correction parameter calculation is completed), that is, the actual performance of the apparatus. At the time of operation, protection control arithmetic processing including signal cable health monitoring processing is executed to perform protection control of the power system. In the signal cable soundness monitoring process, the soundness of the signal cable is monitored by determining whether or not a predetermined connection state signal is input to the input terminal 41b.

  As described above, according to the present embodiment, the soundness of the signal cable is expressed in the input terminal of the reference signal which is used for the adjustment work performed before the apparatus is actually operated and is not used thereafter. Since the connection status signal is input, a signal cable that relays the analog signal between the input unit and the control unit without adding a special circuit other than a simple circuit for generating the connection status signal It is possible to provide a digital protection control device that can constantly monitor the soundness of the device.

Second Embodiment
Next, a digital protection control apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a functional block diagram illustrating a configuration of an input conversion unit and a signal flow included in the digital protection control apparatus according to the second embodiment. Since the other configuration is the same as that of the first embodiment, the description of the overlapping parts is omitted. In addition, the same components as those in the first embodiment are denoted by the same symbols, and redundant description is omitted.

  As shown in FIG. 5, the input conversion unit 2a includes a changeover switch 5 as an input source switching means of the present invention in addition to a signal generator 21, n insulating transformers 22, and a connector 23. The The change-over switch 5 includes, for example, a connection state signal supplied from the signal generator 21 and a reference supplied from the high-precision oscillator 11 (see FIG. 3) to the reference signal input terminal 41d in response to a manual switching operation. One of the signals is selected, and the selected signal is output to the output terminal 23 b of the connector 23.

  When the input characteristic is measured by the changeover switch 5, the reference signal supplied from the high-precision oscillator 11 to the reference signal input terminal is output to the output terminal 23b. After the input characteristic measurement is completed (after the correction parameter calculation is completed), that is, the device During actual operation, the connection state signal supplied from the signal generator 21 is output to the output terminal 23b.

  According to the present embodiment, since the signal cable 3 can be kept attached even when the input characteristic measurement is completed or after the input characteristic measurement is completed, that is, during the actual operation of the apparatus, it is possible to prevent deterioration of the terminal due to the attachment / detachment of the cable. In addition, it is possible to reduce mistakes in cable installation work. Furthermore, it is not necessary to prepare a signal cable 3a (see FIG. 3) for measuring input characteristics.

<Third Embodiment>
Next, a digital protection control device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is an explanatory diagram of the connection to the main control unit by the conversion connector in the digital protection control device according to the third embodiment.

  As shown in FIG. 6, in this embodiment, a conversion connector 6 is attached between the main control unit 4 and the signal cable 3. One of the conversion connectors 6 is connected to the signal cable 3 by being fitted to a connector (not shown) provided at the end of the signal cable 3, and the other is fitted to a connector 41 provided in the main control unit 4. Connected to the control unit 4.

  The conversion connector 6 includes a reference signal input terminal 4d for inputting a reference signal from the high-precision oscillator 11 (see FIG. 3) and a changeover switch 5. The changeover switch 5 includes the main control unit 4. At the time of input characteristic measurement, the reference signal supplied to the reference signal input terminal 4d is input to an output terminal (not shown) connected to the input terminal 41b of the connector 41, or after input characteristic measurement is completed (after correction parameter calculation is completed). During actual operation of the apparatus, connection state signals transmitted to the input terminal 41c are each output.

  According to the present embodiment, even when the input characteristics are measured or after the input characteristics are measured, that is, when the apparatus is actually in operation, as in the second embodiment, the deterioration of the terminal due to the attachment / detachment of the cable is prevented, and the mistake of the cable installation work is reduced. At the same time, it is not necessary to prepare a signal cable 3a (see FIG. 3) for measuring input characteristics. In addition, since the signal cable 3 is not used for transmission of the reference signal supplied from the high-precision oscillator 11, it is possible to suppress a decrease in accuracy of the reference signal that is input accordingly.

<Fourth embodiment>
Next, a digital protection control apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a functional block diagram showing a configuration of a main control unit and a signal flow included in the digital protection control apparatus according to the fourth embodiment.

  As shown in FIG. 7, the main control unit 4 a according to the present embodiment includes a connector 41 a in which the connector 41 and the conversion connector 6 in the third embodiment (see FIG. 6) are integrated in the main control unit 4. Prepare. The operation and effect are the same as in the third embodiment.

<Operation flow of the entire device>
Finally, the operation flow of the digital protection control apparatus according to the present invention will be described with reference to FIG. FIG. 8 is a flowchart showing an operation flow of the digital protection control apparatus.

  First, in step S11, as a preparation for measuring the input characteristics of each analog signal prior to actual operation of the apparatus, as shown in FIG. Necessary equipment and signal lines are connected so as to be supplied to the main transformer 1 and the main control unit 4 which are input transformers, respectively.

  Next, in step S12, the reference signal is actually supplied from the high-precision oscillator 11, and the main control unit 4 takes in and compares the reference signals input from the two systems, thereby calculating the correction parameter for each analog signal. To do.

  When calculation of the correction parameter is completed, in the subsequent step S13, in order to actually operate the apparatus, as shown in FIG. 4, the main transformer 1 as an input transformer is connected to the power system to be protected and input. The signal line connection is changed so that the connection state signal is supplied from the input conversion unit 2 (or 2a) to the main control unit 4 (or 4a). I do.

  Hereinafter, in steps S14 to S18, the protection of the power system is controlled by executing a predetermined protection control calculation while monitoring the soundness of the signal cable.

  More specifically, first, in step S14, the main control unit 4 (or 4a) determines the presence or absence of a connection state signal based on whether or not the value of the input signal is within a predetermined range, and detects the connection state signal. If the process succeeds ("Yes" in step S15), the process proceeds to step S16, each analog signal is input, the input value is corrected, and a predetermined protection control operation is performed to perform the necessary protection control operation. Then, the process returns to step S14 and the same process is repeated. On the other hand, if the detection of the connection state signal is not successful (“No” in step S15), the process proceeds to step S17, and the cable connection abnormality processing (details of details) such as sounding an alarm sound and locking the protection control operation state is performed. (Description is omitted). Subsequently, if the operation of stopping the apparatus is performed in step S18 (“Yes” in step S18), the operation is terminated. If not (“No” in step S18), the process returns to step S14. Repeat the above process.

  Although the description of the embodiment is finished as described above, the embodiment of the present invention is not limited to this, and can be appropriately changed without departing from the gist of the present invention. For example, the adjustment work for calculating the correction parameter is not limited to before the operation of the apparatus, but may be appropriately performed in a periodic inspection after the apparatus is operated. In addition, the reference signal output from the high-precision oscillator is not supplied to the main transformer via the precision amplifier, but is supplied directly to the input converter, so that only the correction parameters for the transmission path downstream from the input converter are calculated. You may make it do.

S Digital protection controller 1 Main transformer (input transformer)
11 High precision oscillator (reference signal supply unit)
12 Precision amplifier 2, 2a Input converter (input unit)
21 Signal Generator 22 Insulation Transformer 23 Connector 23a, 23b Output Terminal 3, 3a Signal Cable 4, 4a Main Control Unit (Control Unit)
41 Connector 41a Analog signal input terminal 41b Reference signal / connection state signal input terminal 41c Connection state signal input terminal 41d Reference signal input terminal 42 Filter 43 Multiplexer 44 A / D converter 45 CPU
5 selector switch (input source switching means)
6 Conversion connector

Claims (9)

An input unit having a plurality of channels for inputting an analog output signal from an input transformer for measuring the amount of electricity in the power system and outputting an analog signal obtained by converting the signal level;
A control unit that converts the analog signal output from the input unit into a digital signal and inputs the digital signal, executes a predetermined protection control calculation based on the digital signal, and performs protection control of the power system;
A digital protection control device connected by a detachable signal cable for transmitting the analog signal,
The signal cable includes a signal line that transmits the analog signal, a signal line that transmits a connection state signal output from the input unit, and a connector that fits into a connector included in the control unit,
The controller is
The same A / D converter that uses the input of the reference signal supplied from the reference signal supply unit without going through the input unit and the input of the connection state signal for the input of the analog signal during the adjustment operation Using
During the adjustment work, the reference signal supplied from the reference signal supply unit without passing through the input unit, and the reference signal supply unit input as the analog signal through the input unit and the signal cable. By calculating a correction parameter for correcting the analog signal input thereafter by comparing with a reference signal,
After completing the calculation of the correction parameter, input the connection state signal to monitor the soundness of the signal cable ,
The digital protection control device, wherein the reference signal and the connection state signal are input from the same input terminal of the connector provided in the control unit. A reference signal input terminal for inputting the reference signal and an input source switching means are provided on a transmission path that connects the output terminal of the connection state signal provided in the input unit and the input terminal,
The input source switching means switches between the reference signal input to the reference signal input terminal and the connection state signal supplied from the output terminal, and relays it to the input terminal. The digital protection control device according to claim 1 . The reference signal input terminal and the input source switching unit are provided in a conversion connector that is detachably mounted between the connector provided in the signal cable and the connector provided in the control unit. Item 3. The digital protection control device according to Item 2 . 3. The digital protection control device according to claim 2 , wherein the signal cable includes the reference signal input terminal and the input source switching unit. Digital protective control apparatus according to claim 2, wherein the reference signal input terminal and the input source switching means, characterized in <br/> be provided in the input unit. The controller is
An input source that relays either the reference signal input terminal for inputting the reference signal, the connection state signal input terminal for inputting the connection state signal, or the reference signal or the connection state signal to an internal circuit The digital protection control device according to claim 1, further comprising switching means. The connection status signal is a voltage signal or current signal of the direct current or alternating current, a clock signal, or any one of claims 1 to 6, characterized in that the telecommunications signal or an optical communication signal in accordance with a predetermined protocol The digital protection control device according to the item. An input unit having a plurality of channels for inputting an analog output signal from an input transformer for measuring the amount of electricity in the power system and outputting an analog signal obtained by converting the signal level;
A control unit that converts the analog signal output from the input unit into a digital signal and inputs the digital signal, executes a predetermined protection control calculation based on the digital signal, and performs protection control of the power system;
A health monitoring method for monitoring the health of the signal cable in a digital protection control device connected by a detachable signal cable for transmitting the analog signal,
The signal cable includes a signal line that transmits the analog signal, a signal line that transmits a connection state signal output from the input unit, and a connector that fits into a connector included in the control unit,
The controller is
The same A / D converter that uses the input of the reference signal supplied from the reference signal supply unit without going through the input unit and the input of the connection state signal for the input of the analog signal during the adjustment operation Using
The reference signal and the connection state signal are input from the same input terminal of the connector provided in the control unit,
The control unit is supplied from the reference signal supply unit supplied without going through the input unit, and from the reference signal supply unit inputted as the analog signal through the input unit and the signal cable. A first step of calculating a correction parameter for correcting the analog signal input thereafter by comparing with a reference signal;
And a second step of monitoring the soundness of the signal cable by inputting the connection state signal. 9. The soundness monitoring according to claim 8 , wherein the connection state signal is a DC or AC voltage signal or current signal, a clock signal, or an electric communication signal or an optical communication signal according to a predetermined protocol. Method.

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