KR20040043916A - Apparatus for maintaining the constant voltage of power generator with a power compensating circuit - Google Patents

Abstract

PURPOSE: A constant voltage device having a power compensation circuit is used for a generator is provided to maintain a load voltage of a generator in a state of constant voltage by controlling the power compensation circuit for compensating low voltage according to a variation of output voltages. CONSTITUTION: A constant voltage device having a power compensation circuit is used for a generator includes a voltage detector, an automatic constant voltage controller, a semiconductor, a buffer load, and a control power supply. The voltage detector(20) measures continuously a real voltage of a generator(70). The automatic constant voltage controller(30) compares the real voltage to a reference voltage and generates a control output according to a compared result. The semiconductor(50) receives the control output and controls the power by using a power semiconductor device. The buffer load(60) is used for receiving the controlled power from the semiconductor. The control power supply(40) is connected to the automatic constant voltage controller in order to control the power of the generator.

Description

Constant voltage device for generator with power compensation circuit {APPARATUS FOR MAINTAINING THE CONSTANT VOLTAGE OF POWER GENERATOR WITH A POWER COMPENSATING CIRCUIT}

The present invention relates to a constant voltage device for a generator having a power compensation circuit for controlling the output voltage of a mobile generator (including emergency and portable) for a steel mill to a constant voltage, and more specifically, a mobile generator (emergency use) used in an electrostatic work of a steel mill. The present invention relates to a constant voltage device for a generator having a power compensation circuit including a power compensation buffer load device unit and a power semiconductor device unit for controlling the output voltage.

In general, due to the nature of steel mills, maintenance work cannot be carried out with only one of the unit facilities stopped.

At this time, the emergency generator is operated and the precision test work of various electric devices is performed with the power supply, but when the fluctuation of a power supply voltage exceeds a predetermined value, the said work cannot be performed.

In particular, when using a vacuum breaker tester VIDAR 10 ~ 60Kv DC, which is a high pressure circuit breaker test equipment, if the constant voltage is not applied, it may be impossible to test the high voltage breaker or incorrect data may be generated.

First, the power compensation response time (characteristic) which is one of the features of the present invention prior to the problems of the prior art will be described.

In general, the low voltage phenomenon is an instantaneous voltage drop caused by sudden load fluctuations. In general, the IEEE Std1100-1992 STANDARD maintains a voltage drop of more than 20% for 0.05 ~ 0.1 sec. (See Fig. 4), the allowable voltage range is within + 20% and -30%.

If all the electric equipment fluctuates more than this voltage, it is considered that the electric equipment is unable to perform its performance. Therefore, the power compensation response time must be faster than this time to maintain the constant voltage to prevent the occurrence of low voltage (SAG). Has the following problems:

First, a constant voltage circuit using a conventional constant voltage diode (Zener diode) or a transistor disclosed in the Republic of Korea Utility Model Application No. 1998-27498 by comparing the reference voltage and the actual voltage when the voltage fluctuates by a semiconductor device such as a transistor or a zener diode Because it was a method of maintaining the constant voltage by adjusting the voltage, there was no way to maintain the constant voltage when the power supply was insufficient, and it was possible to use only a low capacity control power supply.

Secondly, there was no way to maintain the constant voltage when the power supply capacity was insufficient even in the constant voltage device using a transformer or a variable resistor disclosed in Korean Utility Model Application No. 1986-21748 and Korean Patent Application No. 194-15331.

Third, the method of changing the excitation current of the generator, which is a generator (including emergency and portable) constant voltage control method, to maintain the constant voltage by decreasing the generator rotation speed, has no basis for compensation time.

In addition, since the power supply voltage cannot be supplied above the rated power generator, there was no way to compensate for the occurrence of low voltage when a load exceeding the rated output is momentarily applied due to the increase of the load.

In addition, the response time due to voltage fluctuation may be delayed because the number of revolutions of the generator has to be changed. (There is no published estimate that the voltage can be compensated within the low voltage regulation time.)

Fourth, the conventional automatic voltage regulation (AVR) circuit for converting the transformer terminal has a disadvantage in that the response time for the low voltage as a method of switching the transformer terminal (TR TAP) in response to the voltage change.

Fifth, in the method of maintaining constant voltage by discharging the capacitor charging voltage, when the instantaneous low voltage occurs, the inverter generates the voltage equal to the input drop by using the energy stored in the capacitor and adds it in series to the input power. The low voltage compensator has limited capacities and sizes, making it impossible to maintain a constant voltage during long periods of low voltage.

Conventional mobile generators, small generators, or emergency generators generate greater voltage fluctuations due to load fluctuations than general power sources (commercial power supplied from power plants). This difficult problem is caused by the above problems when the measuring machine, the rotating machine, the various electronic products, etc., which require precision voltage are supplied from the portable generator, the small generator, or the emergency generator. I can't. In particular, in case of emergency electric work after power failure of general power (commercial power supplied from power plant), the industrial site can be maintained smoothly due to the above problems due to the above-mentioned problems. There is a problem that cannot be repaired.

In order to solve the above problems, the present invention controls the low voltage compensation control device (power semiconductor device) in accordance with the output voltage fluctuations to reduce the power consumed by the power compensation load device (power consumption device such as resistor or heater). By suppressing fluctuations in output voltage and maintaining generator load voltage at constant voltage, there is no fear of low voltage caused by insufficient power supply capacity, and voltage fluctuation resulting from delay in response of generator constant voltage recovery when voltage fluctuation occurs due to generator load fluctuation. It can be used for generator (emergency and portable) and general transformer load by maintaining constant voltage even in case of long voltage drop and load fluctuation, and from small precision control power supply to constant voltage power for large power Obtain a power compensation circuit that enables applications The purpose is to provide a constant voltage device for a generator.

1 is a block diagram of a constant voltage device for a generator having a power compensation circuit according to the present invention;

2 is a detailed view of an automatic constant voltage controller constituting a constant voltage device for a generator having a power compensation circuit according to the present invention;

3 is a detailed view of a low voltage compensation power semiconductor unit constituting a constant voltage device for a generator having a power compensation circuit according to the present invention;

4 is an operational flowchart of a constant voltage device for a generator having a power compensation circuit according to the present invention;

5 is a waveform diagram showing a period (time) of instantaneous low voltage phenomenon before the present invention is applied;

6 is a waveform diagram showing a normal load voltage waveform to which a voltage compensation action is applied by applying a constant voltage device for a generator having a power compensation circuit according to the present invention;

7 is a circuit diagram showing a call angle determining method of a power device of a constant voltage control unit constituting a constant voltage device for a generator having a power compensation circuit according to the present invention;

8 is a circuit diagram for explaining the constant voltage operation of the power compensation buffer load according to the change in the firing angle of the present invention;

9 is a gate pulse and voltage waveform diagram of a power semiconductor unit in a normal state of the present invention;

FIG. 10 is a waveform diagram illustrating a constant voltage action of a power compensation buffer load according to a change in firing angle during voltage fluctuations of the present invention.

♠ Explanation of symbols on the main parts of the drawings.

10: load 20: voltage detector 30: automatic constant voltage controller

40: control power supply unit 50: low voltage compensation semiconductor unit

60: power compensation buffer load 70: generator 31: detection voltage applying unit

32: reference voltage application unit 33: comparison unit 34: constant voltage control unit

501: Normal waveform 502: Compensation waveform during voltage drop

503: compensation waveform at the time of voltage rise

In order to achieve the above object, the present invention is a device for maintaining the output voltage for the load 10 of the steel mill mobile and emergency generator 70 at a constant voltage, continuously measuring the actual load voltage of the generator 70 A voltage detector 20; An automatic constant voltage controller (30) which continuously compares the difference between the actual load voltage and the reference voltage measured by the voltage detector (20), amplifies a change amount proportional to the difference value, and generates a power semiconductor control output; A low voltage compensation power semiconductor unit 50 for controlling the power flowing by using the power semiconductor element 51 by receiving the power semiconductor control output generated by the automatic constant voltage controller 30; A power compensation buffer load unit 60 for receiving and consuming power controlled by the low voltage compensation power semiconductor unit 50; It is connected to the automatic constant voltage control unit 30 provides a constant voltage device for a generator having a power compensation circuit, characterized in that consisting of a control power supply 40 for controlling and supplying power from the generator 70.

The present invention also provides a detection voltage applying unit 31 for applying the voltage detected by the automatic constant voltage control unit 30 from the voltage detection unit 20, a reference voltage unit 32 for adjusting a reference voltage, and the detection. Comparator 33 for comparing the voltage output from the voltage applying unit 31 and the reference voltage unit 32, and a constant voltage for outputting the control value compared from the output to the low-voltage compensation power semiconductor unit 50 It is to provide a constant voltage device for a generator having a power compensation circuit, characterized in that the control section 34,

In addition, the present invention is a power semiconductor device to which the low-voltage compensation power semiconductor unit 50 is applied to the power semiconductor control output generated by the automatic constant voltage control unit 30 is a thyristor or an IGBT. It provides a constant voltage device for a generator having a power compensation circuit, characterized in that configured to supply a controlled power to the power compensation buffer load unit (60).

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration of the present invention.

1 is a configuration diagram of a generator constant voltage device having a power compensation circuit according to the present invention, Figure 2 is a detailed view of the automatic constant voltage control unit constituting a constant voltage device for a generator having a power compensation circuit according to the present invention.

As shown in Figs. 1 and 2, the generator generates power with a capacity of 120% or more of the commercial load rated output (considering the low voltage regulation), and the remaining power (power above the rated output) is the power compensation buffer load. The load variation is controlled by controlling the power flowing through the power compensation buffer load 60 by controlling the low-voltage compensating power semiconductor 50 when the load 60 changes. Load-side voltage is able to maintain a constant voltage even if it is described in detail as follows.

When the load voltage fluctuates due to the load variation, the voltage detector 20 continuously measures and detects the actual load voltage, and the change amount of the voltage is automatically applied to the automatic constant voltage controller 30 as an actual voltage value, that is, a control value. The differential amplifier 33 of the constant voltage control unit 30 receives this control value, continuously compares the difference between the actual load voltage and the reference voltage, and amplifies the change amount proportional to the difference value, thereby generating a power semiconductor control output. .

This control output is applied to the low voltage compensation power semiconductor 50 to control the power flowing through the power semiconductor to control the power consumed by the power compensation buffer load 60 to maintain the load voltage at a constant voltage. It is.

That is, the gate firing angle (alpha angle) is changed in the power semiconductor of the low voltage compensation power semiconductor device by the difference with the rated voltage to control (a.) The power consumed by the low voltage compensation buffer load device. The voltage can be maintained at a constant voltage within the electrical regulation time.

3 is a detailed view of a low voltage compensation power semiconductor unit constituting a constant voltage device for a generator having a power compensation circuit according to the present invention, wherein the automatic power supply 52 controls the power semiconductor 51 in the constant voltage control unit. ) Is applied to the power compensation buffer load unit (BUFFER LOAD).

Figure 4 is a flow chart of the operation of the constant voltage device for a generator having a power compensation circuit according to the present invention, illustrating the function of maintaining the constant voltage when the generator starts and voltage changes after the load connection.

Fig. 5 is a waveform diagram showing the period (time) of the instantaneous low voltage phenomenon before the present invention is applied, indicating that one cycle is 16.67 milliseconds and the power semiconductor turn-on time is short.

FIG. 6 is a waveform diagram illustrating a normal load voltage waveform in which a voltage compensating action is applied by applying a constant voltage device for a generator having a power compensating circuit according to the present invention.

FIG. 7 is a circuit diagram illustrating a firing angle determination method of a power device of a constant voltage control unit constituting a constant voltage device for a generator having a power compensation circuit according to an embodiment of the present invention, wherein the actual voltage 332 and the reference voltage ( 333) That is, when the required constant voltage value is input and the difference is amplified by the differential amplifier 331 and applied to the constant voltage controller (FIRING UNIT), the firing phase angle () is determined to generate a gate pulse synchronized with the input power. It is applied to the gate of the semiconductor device for.

The constant voltage action of the power compensation buffer load according to the firing angle change of the present invention is described in detail as follows.

FIG. 8 is a circuit diagram illustrating the constant voltage operation of the power compensation buffer load according to the change of the firing angle of the present invention. FIG. 9 is a gate pulse and voltage waveform diagram of the power semiconductor unit in the normal state of the present invention. The waveform diagram showing the constant voltage action of the power compensation buffer load according to the change in the firing angle during the voltage fluctuation of the present invention.

As shown in FIGS. 8 to 9, in a steady state in which the voltage of the load 10 does not fluctuate, a gate pulse firing phase angle having a phase angle (90 degrees) as shown in FIG. 9 is generated, and a waveform such as E01 is generated in TH1. And a waveform such as E02 is generated at TH2 to maintain the load voltage at a normal voltage, and when the load voltage drops due to the load variation, as shown in FIG. 10A, gate firing timing according to the voltage drop amount. As a result, the gate pulse phase angle is increased to generate waveforms such as E1 and E2 in the power semiconductors TH1 and TH2, respectively.

When the load voltage increases due to the load variation, as shown in FIG. 10B, the gate pulse phase angle decreases according to the increase in voltage, and waveforms such as E3 and E4 are generated in the power semiconductors TH1 and TH2, respectively. do.

Due to the voltage compensation action, the voltage of the load 10 connected in parallel with the power compensation buffer load can be maintained at a constant voltage.

The voltage change across the power compensation buffer load 60 according to the change of the gate pulse angle is calculated by the following formula.

E: Average voltage of buffer load for power compensation

Once again, the features of the present invention will be described.

In general, fluctuations in power supply voltage (voltage drop or voltage rise) are caused by insufficient supply capacity of power supply voltage. In general power supply (commercial power supply from power plant), there is almost no shortage of power supply capacity except in special cases. The power generated from generators (portable generators or emergency generators) is limited in supply capacity, which can lead to severe fluctuations in the power supply voltage caused by load changes.

Therefore, in order to solve this problem, a small (portable generator or emergency generator) generator generates power higher than the rated value (more than 120%-considering the allowable voltage fluctuation width), and the remaining power other than the rated power is consumed by the buffer load device. When the voltage fluctuates due to the load fluctuation, the power semiconductor device is controlled to return the power consumed by the buffer load to the load to prevent the voltage from fluctuating so that the constant voltage can be maintained.

Therefore, according to the present invention, since the low voltage compensation power compensation device is used, the control of the power supply voltage fluctuation (especially low voltage generation) resulting from the lack of power supply capability of the generator (especially for the emergency and portable small generators) is enabled. It enables the continuous voltage detection and compensation to be made quickly so that a stable power supply with a constant voltage can be achieved within the prescribed time, and it can meet the constant voltage regulation of the emergency generator required for power outages of steel mills.

In addition, the constant voltage control device including the power compensation buffer load, which is the core device of the present invention, and the power semiconductor device unit for controlling the same, is expected to be applicable to general transformer loads as well as generators for steelworks blackout work. It can be expected to provide more stable power supply of the required industrial electric control system and electric drive drive device.

Claims (3)

In the apparatus for maintaining the output voltage to the load 10 of the steel mill mobile and emergency generator 70 at a constant voltage, A voltage detector 20 which continuously measures the actual load voltage of the generator 70; An automatic constant voltage controller (30) which continuously compares the difference between the actual load voltage and the reference voltage measured by the voltage detector (20), amplifies a change amount proportional to the difference value, and generates a power semiconductor control output; A low voltage compensation power semiconductor unit 50 for controlling the power flowing by using the power semiconductor element 51 by receiving the power semiconductor control output generated by the automatic constant voltage controller 30; A power compensation buffer load unit 60 for receiving and consuming power controlled by the low voltage compensation power semiconductor unit 50; The constant voltage device for a generator having a power compensation circuit, characterized in that the control power supply unit 40 is connected to the automatic constant voltage control unit 30 to control and supply power from the generator 70. The method of claim 1, The automatic constant voltage controller 30 includes a detection voltage applying unit 31 for applying a voltage detected from the voltage detector 20, a reference voltage unit 32 for adjusting a reference voltage, and the detection voltage applying unit 31. ) And a comparison unit 33 for comparing the voltage output from the reference voltage unit 32, and a constant voltage control unit 34 for outputting the control value compared therefrom to the power semiconductor unit 50 for the low voltage compensation. A constant voltage device for a generator having a power compensation circuit, characterized in that the configuration. The method of claim 1, The low voltage compensation power semiconductor unit 50 is configured as a thyristor or an IGBT device to receive the power semiconductor device to which the power semiconductor control output generated by the automatic constant voltage controller 30 is applied. A constant voltage device for a generator having a power compensation circuit, characterized in that for supplying controlled power to the power compensation buffer load unit (60).