JP4103789B2 - Protection control device - Google Patents

Description

  The present invention relates to a protection control device, and more particularly to a protection control device in which a protection arithmetic unit and a measurement unit provided in the protection control device share parts.

FIG. 3 shows a schematic configuration diagram of the protection control device, and a plurality of voltages and currents of the power system are taken into the protection control device via a transformer (VT) and a current transformer (CT), respectively. FIG. 3 shows a state where only one current is captured, but other currents and voltages are captured in the same manner. Reference numeral 1 denotes a protection input converter, and reference numeral 2 denotes a measurement input converter, each of which converts an input signal into a predetermined value. Reference numeral 3 denotes a protection analog input unit, which is not shown in the figure, but includes a filter, a sampling hold circuit, a multiplexer, an analog / digital converter, etc., and a digital operation whose protection is a digital output. Introduced into the processing unit 4, a predetermined calculation for protection is performed, and a trip signal or the like is output depending on the result.
On the other hand, after the output of the measurement input converter 2 is introduced into the measuring device 5 made of a transducer and measured, the measured value is checked on the display unit of the protection control device, and the higher-order transmission processing unit 6 is connected. It is transmitted to the upper level via.

A device such as that disclosed in Patent Document 1 is known as a device that captures signals for protection and measurement.
JP 2002-328141 A

  In the protection control device for the purpose of protection and measurement as shown in FIG. 3, the full scale that is the current capturing range is different for protection and measurement depending on the purpose of use. That is, the current input range for protection is 0 to CT rating × 20 times, and the current input range for measurement is 0 to CT rating × 2 times. This is due to the difference that the purpose of measurement is to measure a large current when an accident occurs in the power system, while the purpose of measurement is to measure a load current that is constantly flowing.

The protection control device is configured as shown in FIG. 3 in order to satisfy the protection relay and measurement performance, but has the following problems.
(1) The protection converter has an input converter for protection and measurement.
(2) The protection control device has an analog input unit for both protection and measurement.
(3) The protection control device has an arithmetic processing unit for protection and measurement.
As described above, since the protection control device is mounted with overlapping hardware, the space for mounting is strict, the whole is large, and the cost is high.
In Patent Document 1, there is no idea that when a measurement signal is introduced into an analog input unit, a protection empty channel is introduced and the accident detection relay is introduced in the same channel.

  Accordingly, an object of the present invention is to provide a protection control device that reduces hardware and reduces costs.

According to a first aspect of the present invention, in the protection control device that takes in the voltage and current of the power system into the arithmetic processing unit via the input converter and the analog input unit, and executes the calculation for protection and the calculation for measurement. The converter is shared for protection and measurement, the analog input unit and arithmetic processing unit are separated for the main detection relay element and the accident detection relay element, respectively, and the measurement signal from the input converter is the accident detection Introducing into the same channel as the analog input unit for the relay element to make the full scale common, and executing the calculation calculation process in the calculation idle time for the accident detection relay element in the calculation processing unit, and the correction value setting means And the measurement calculation in the calculation processing unit is performed using the correction value set by the setting means.

According to a second aspect of the present invention, the measured calculation value Iout in the arithmetic processing unit for the accident detection relay element is obtained by Iout = Ki × Iin, where Iin is a signal from the analog input unit and Ki is a correction coefficient. It is characterized by.

According to a third aspect of the present invention, an output unit including the correction value setting means and a display unit for displaying a measurement result is attached to an arithmetic processing unit for an accident detection relay element.

  As described above, according to the present invention, in the protection control device that takes in the voltage and current of the power system into the arithmetic processing unit via the input converter and the analog input unit, and executes the calculation for protection and the calculation for measurement. Since the input converter is used for both protection and measurement, and the analog input section uses an empty channel for protection or uses the same channel as the accident detection relay element, This makes it possible to reduce the size and reduce the cost. In addition, when a measurement signal is introduced into a protection empty channel, the measurement calculation is executed using the protection calculation idle time as a gain N times that of the protection signal, and a correction value is added during the measurement calculation. Since the calculation is performed, high-precision calculation for measurement is possible.

FIG. 1 shows an embodiment of the present invention. Reference numeral 10 denotes an input converter that is commonly used for protection and measurement. In the figure, only one input channel is representatively displayed. The input converter 10 includes a plurality of currents detected from the power system. Are input through the channels. An analog input unit 20 includes a protection input unit 21 and a measurement input unit 22. The measurement input unit 22 is multiplied by N times (for example, to make full scale 1 / N for protection). N = 10) gain circuits are provided.
Each of the protection and measurement input units branches from the same channel of the input converter 10 and is input to the protection empty channel for measurement.
Reference numeral 30 denotes an arithmetic processing unit. The arithmetic processing unit 30 includes a processing unit 31 that executes a protection calculation and a processing unit 32 that executes a measurement calculation. The measurement calculation process is a protection calculation process. The calculation process is executed using the idle time. The measurement processing means 32 receives a correction value for correction at the time of calculation, thereby improving accuracy. Reference numeral 40 denotes a display unit for displaying a measurement result or an output unit for performing a high-order transmission process. The output unit 40 includes a correction value setting unit 41 for outputting a correction value at the time of calculation for measurement.

The accuracy required for the operation value of the relay, which is a protective calculation, is generally about 5%. On the other hand, the accuracy required for measurement is generally about 1%. For this reason, a more accurate measurement function is realized by providing a correction value at the time of calculation for measurement and setting the correction value so that no error occurs at the rated level. As a calculation formula for the measurement value, if the value input from the analog input unit 20 is Iin, the correction coefficient Ki, and the measurement result is Iout,
Iout = Ki × Iin.

  The above is a description of the current element, but in the case of the voltage element, the full scale required for protection and measurement is substantially the same. Therefore, both the input converter and the analog input unit are for protection and measurement. Sharing. However, in the arithmetic processing unit, calculation using the correction value is executed in the same manner as in the case of the current element in order to increase the measurement accuracy.

Next, the operation will be described.
The current detected through the current transformer CT is insulated by the input converter 10 and converted to an appropriate level and then output to the analog input unit 20. The analog input section, the input signal San bling at a predetermined San bling frequency, and is held. At this time, the branched measurement signal is adjusted to N times the gain for protection through the gain adjustment circuit. The held protection and measurement signals for each input channel are sequentially scanned by the multiplexer, A / D converted, and stored in the memory. The arithmetic processing unit 30 sequentially takes out digital signals stored in the memory and executes a protection operation for the relay based on a predetermined algorithm. In this relay calculation, in general, an accident determination is performed in an instant within several tens of ms by high-speed calculation processing.

On the other hand, since the measurement process only needs to obtain a calculation result at a relatively low speed of about several hundreds of milliseconds, the calculation processing unit 30 uses the idle time of the relay calculation to store the digital signal stored in the memory of the measurement input unit 22. The measurement processing unit 32 executes the measurement calculation process using the correction value Ki set by the correction value setting unit 41, and the result is displayed on the output unit 40. In addition, if necessary, it is transmitted to a higher level via a higher level transmission processing unit.
The protection relay is generally separated into a main detection relay and an accident detection relay, and calculation is performed by the respective relays. However, the signal input to the measurement input unit 22 is either for main detection or for accident detection. Is possible.

  According to this embodiment, the input conversion unit can be used for protection and measurement, and the analog input unit for measurement can use an empty channel for protection by setting the gain to N times (10 times). This is intended to reduce hardware. In addition, the calculation processing for measurement can be performed by a common calculation processing unit by using the free time of the calculation processing for protection, and the calculation value can be calculated by using the correction value at the time of measurement calculation. The high precision is maintained, and the apparatus can be downsized, the cost can be reduced, and the precision can be improved.

  FIG. 2 shows another embodiment, and the same or corresponding parts as those in FIG. As described above, the protection relay is composed of a main detection relay and an accident detection relay, and malfunctions are prevented by outputting a trip signal or the like as a logical product of the protection relay. In such a protection relay, the main detection relay is composed of a highly functional relay element so that the accident section can be identified, and the accident detection relay is composed of a simple relay element for detecting whether or not an accident has occurred. Has been. For this reason, the main detection relay is required to have a full scale of about N times (10 times) the rated value, but the accident detection relay often has no problem with a relatively small full scale that is several times the rated value. This is based on the fact that the main detection relay determines the accident section and the direction of the accident while the accident detection relay generally only needs to determine whether or not an accident has occurred.

The embodiment shown in FIG. 2 is made based on such a premise. That is, the analog input unit 20 is separated into a main detection relay input unit 23 and an accident detection relay input unit 24, and an output signal from the input converter 10 is input to both the input units 23 and 24, respectively. Further, the accident detection relay input unit 24 sets the full scale to several times and takes in a measurement signal so that both full scales are the same. Therefore, a common channel is used for the accident detection relay and the measurement. Reference numeral 33 denotes a main relay arithmetic processing unit, which executes a main relay protective arithmetic processing. An accident detection relay arithmetic processing unit 34 performs an accident detection calculation and a measurement calculation process. When this calculation calculation process is executed, it is executed using the idle time in which the protection accident detection relay is calculated, and the calculation is performed using the correction value set by the correction value setting means. Reference numeral 40 denotes an output unit. This output unit may be provided individually as shown in FIG. 1, but in this embodiment, it is attached to the arithmetic processing unit 34 for the accident relay to further reduce the mounting space and cost. Yes.
As for the voltage element, the protection and measurement are shared in the same way as the current, and the necessary full scale is substantially the same for the protection and measurement. The calculation for measurement is shared by using the spare time for the protection calculation for the accident detection relay.

According to this embodiment, in addition to the effects of the embodiment of FIG. 1, the input for measurement is taken into the accident detection relay, the full scale for measurement is shared with the accident detection relay, and the analog input section is shared. As a result, the A / D converter of the analog input unit can be increased in resolution. In addition, by joining the output unit to the operation processing unit for accident detection relay, the conventional dedicated display unit is not required, hardware can be reduced, and higher costs can be reduced. It is.

The schematic block diagram of the protection control apparatus which shows the Example of this invention. The schematic block diagram of the protection control apparatus which shows the other Example of this invention. The schematic block diagram of the conventional protection control apparatus.

Explanation of symbols

1 ... Protective input converter
2 ... Input converter for measurement
3… Protective analog input
4 ... Analog input for measurement
5 ... Measuring device
6, 40 ... Output section
10 ... Input converter
20 ... Analog input section
30 ... arithmetic processing unit

Claims (3)

In a protection control device that takes in voltage and current of an electric power system to an arithmetic processing unit via an input converter and an analog input unit, and executes a calculation for protection and a calculation for measurement, the input converter is measured for protection The analog input unit and the arithmetic processing unit are separated for the main detection relay element and the accident detection relay element, respectively, and the measurement signal from the input converter is an analog input unit for the accident detection relay element. In the same channel, the full scale is made common, the calculation processing is executed in the calculation idle time for the accident detection relay element in the calculation processing unit, and the correction value setting means is provided. A protection control device configured to perform measurement calculation in the calculation processing unit using a set correction value . The measured calculation value Iout in the arithmetic processing unit for the accident detection relay element is obtained by Iout = Ki × Iin, where Iin is a signal from the analog input unit and Ki is a correction coefficient. The protection control device described . The protection control device according to claim 1 or 2, wherein the correction value setting means and an output unit including a display unit for displaying a measurement result are attached to an arithmetic processing unit for an accident detection relay element .

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