JPH0560801A - D/a converter - Google Patents

Abstract

PURPOSE:To obtain a D/A converter which converts voltage and current data of effective values calculated by means of a digital computer that simulates the phenomenon of a system in real time into sine-wave AC voltage and current data. CONSTITUTION:This D/A converter is provided with an instantaneous value data converting section 6 which inputs voltage and current data of effective values calculated by means of a computer 2 and frequencies and phase angles at every computing time and converts the data into voltage and current data of instantaneous values and a D/A-converting section 3 which D/A-converts the voltage and current data of instantaneous values into since-wave AC voltage and current data at every D/A-outputting time. Therefore, the since-wave AC voltage and current data which can be inputted to a device to be tested can be obtained from the digital voltage and current data of effective values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a D / A converter, and more particularly to a D / A converter for a power system analysis simulator system that can simulate, for example, a large-scale power system in real time using a digital computer. Is.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a conventional D / A converter disclosed in, for example, Japanese Patent Publication No. 27886/1990. In FIG. 2, 1 is an input unit for inputting system data or system state, 2 is a computer for calculating transient phenomena of voltage and current of a power system by a general-purpose transient analysis program EMTP or the like under the input condition from the input unit 1. 3 is a D / A converter for converting the voltage and current data obtained by the computer 2 from digital data to an analog value, and 4 is the input of the voltage and current values converted to analog values by the D / A converter 3. Protective relay device as device under test for testing, 5 is input section 1,
It is a D / A conversion device including a computer 2 and a D / A conversion unit 3.

Next, the operation will be described. System data or system state S1 is input from the input unit 1 to the computer 2, and the computer 2 performs transient phenomenon calculation (instantaneous value calculation) under the conditions of the input unit by EMTP or the like, and the resulting voltage, The current data is directly output to the D / A conversion unit 3 as digital data S2. The D / A converter 3 converts the input digital data S2 into an analog signal S3 and supplies it to the protective relay device 4. The protective relay device 4 is a device digital output S4 according to the response and sequence of the protective relay unit.
Is output to the computer 2. In addition, the computer 2 is a protective relay device 4
When the device digital output S4 of (1) is input, the transient condition calculation conditions are changed and calculation is performed, and the voltage and current data under the conditions are output to the D / A conversion unit 3 as digital data S2.

[0004]

Since the conventional D / A converter is configured as described above and directly outputs the digital data, which is the instantaneous voltage and current data, by D / A conversion, it outputs. Even if the digital data that is the voltage and current data of the effective value calculated by the stability calculation is directly D / A converted and output, the converted output is a DC component, so that the device under test cannot be tested. was there.

The present invention has been made in order to solve the above problems, and outputs sinusoidal AC voltage and current data using effective value voltage and current data calculated by a computer to be tested. D / that can test equipment
The purpose is to obtain an A converter.

[0006]

D / A according to the present invention
The converter is an instantaneous value data converter that converts the voltage and current data and frequency and the phase angle of the effective value calculated by a computer that simulates the phenomenon of the system in real time into the voltage and current data of the instantaneous value at each calculation time step. And the sine wave AC voltage, which is obtained by digital-analog converting the voltage and current data of the instantaneous value from this instantaneous value data conversion unit at every D / A output time.
And a D / A conversion unit for obtaining current data.

[0007]

According to the present invention, when the computer obtains the voltage and current data and the frequency and the phase angle of the effective value, the instantaneous value data conversion unit converts the voltage and current data to the instantaneous value and further the D / A conversion. To obtain sinusoidal AC voltage and current data.

[0008]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention,
1 to 4 are the same as those of the above conventional device. In the figure, 5A is a D / A converter, 6 is a computer 2 and a D / A
An instantaneous value data conversion unit, which is inserted between the conversion unit 3 and the conversion unit 3, is an amplifier for amplifying the weak analog signal output from the D / A conversion unit 3.

Next, the operation will be described. The computer 2 inputs the system data from the input unit 1 or the system state into the input data S
1, and the device digital output S of the protective relay device 4
4 is input, and under the input conditions, for example, a stability calculation is performed to see fluctuations in the amount of energy in the power system over a long period of time, and the resulting effective value voltage, current data and frequency, and phase angle are calculated. The digital data S2 is output at every calculation time step. The instantaneous value data conversion unit 6 inputs the digital data S2 from the computer 2, and considers the D / A output time interval, and then calculates the sine wave instantaneous value data based on the frequency and the phase angle included in the digital data S2. Select from the wave data table (instantaneous value data for 360 °), multiply by the amplitude value (2 ^1/2 × rms value), and instantaneous voltage / current data table (instantaneous value for 360 ° for each D / A output time interval) Value data). Then, the instantaneous value data converter 6 converts the instantaneous value voltage and current data from the instantaneous value data table into digital data S at each D / A output time interval.
Output as 5. The D / A converter 3 receives the digital data S5 from the instantaneous value data converter 6, digital-analog converts it, and outputs sine wave AC voltage and current data as analog data S3. Amplifier 7 is D
The analog data S3 from the A / A converter 3 is input, this weak analog signal is voltage-amplified or current-amplified to a level required for the protective relay device 4, and then output as analog data S6. The protective relay device 4 is tested using the voltage and current of the analog data S6.

Now, the instantaneous value data conversion unit 6 obtains the instantaneous value voltage and current data from the effective value voltage and current data and the frequency and the phase angle which are updated by the computer 2 at every calculation time step. There is some difference between before and after updating. When this is D / A converted by the D / A converter 3 and output, a sudden change occurs in the sinusoidal AC voltage and current data, and the amplifier 7 cannot follow this change. In order to prevent this, the instantaneous value data conversion unit 5 corrects by calculating the first data of the voltage and current data of the instantaneous value created at the time of updating from the second data and the data output immediately before updating, and D / After A conversion, make sure that there are no sudden changes in the sinusoidal AC voltage and current data.

Although the above embodiments have been described for the case of a large-scale power system, the present invention can be similarly applied to other, for example, a system of a small-scale circuit. Also,
Although a case has been described where the device under test is a protective relay device, it goes without saying that the present invention can be similarly applied to other devices under test.

[0012]

As described above, according to the present invention, the voltage, current data and frequency of the effective value calculated by the computer that simulates the phenomenon of the system in real time, the frequency, and the phase angle of the instantaneous value are calculated for each calculation time step. Instantaneous value data conversion unit for converting into voltage and current data, and instantaneous value voltage and current data from this instantaneous value data conversion unit are digitalized at every D / A output time.
Obtains sinusoidal AC voltage and current data by analog conversion D
Since the A / A converter is provided, there is an effect that the device under test can be tested by obtaining sinusoidal AC voltage and current data from the voltage and current data of the effective value calculated by the computer.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional D / A conversion device.

[Explanation of symbols]

 2 Computer 3 D / A converter 5A D / A converter 6 Instantaneous value data converter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Sakurai 6-1-1 Hamayama-dori, Hyogo-ku, Kobe Mitsubishi Electric Engineering Co., Ltd. Kobe office (72) Hideo Noguchi 1-chome, Wadazaki-cho, Hyogo-ku, Kobe 1-2, Sanryo Electric Co., Ltd. Control Works (72) Inventor Nobuyuki Sato 2-4-1, Nishitsujigaoka, Chofu-shi, Tokyo Inside Technical Research Institute, Tokyo Electric Power Co., Inc. (72) Taro Nakazawa, 2 Nishiazajigaoka, Chofu-shi, Tokyo 4-1-1 TEPCO Technical Research Institute

Claims (2)

[Claims] 1. Instantaneous value data conversion for converting voltage and current data of effective value and frequency and phase angle calculated by a computer that simulates a system phenomenon in real time into instantaneous voltage and current data at each calculation time step. And a D / A converter that obtains sinusoidal AC voltage and current data by digital-analog converting the voltage and current data of the instantaneous value from this instantaneous value data converter at every D / A output time. A D / A conversion device characterized by the above. 2. When the voltage and current data of the instantaneous value is updated, the data to be output next is calculated from the data output one before and the data output one after, and the correction is performed. The D / A conversion device according to claim 1.