JPH0318300A - Automatic power factor regulator - Google Patents

Abstract

PURPOSE:To shorten settling time until an actual power factor becomes a preset value by varying an intermittently driving period of a voltage setter in response to the output current of a synchronous generator. CONSTITUTION:A phase angle phis of a desired power factor is set by a phase angle setter 10. The phase angle phi of the power factor of a synchronous generator 1 is detected by a phase angle detector 11. The current of the generator 1 is detected by a current detector 12. A controller 13 is operated as follows: ¦phiS-phi¦=¦ phi¦ is calculated. In case of ¦ phi¦> (constant value C), the step is advanced to next, and if not, the step is returned to an input. A slope is varied in response to an output current (i), and a reference value (r) varying to a sawtooth wave is calculated. In case of ¦ phi¦>r, the step is advanced to next, and if not, a driving current output is stopped. In the case of phiS>phi, a positive driving current is outputted, and if not, a negative driving current is outputted. Thus, the driving time of a motor 8a is regulated in response to the amplitude of the i to enhance its response.

Description

[Detailed Description of the Invention] "Industrial" Second Field of Application This invention relates to an automatic power factor adjustment device that always keeps the power factor of a synchronous generator constant, and in particular, the present invention relates to an automatic power factor adjustment device that always keeps the power factor of a synchronous generator constant. The present invention relates to an automatic power factor adjustment device that aims to shorten the settling time until the power factor is adjusted.

"Prior Art" FIG. 4 is a block diagram showing the configuration of a conventional automatic power factor adjustment device. In this figure, it is a rotating field type synchronous generator that is rotationally driven by a diesel engine, water wheel, etc. (not shown), and an armature 1a is fixed on the outer circumference side, and a field coil Ib is attached on the inner circumference side. It has a rotating structure. And the armature coil of armature 1a (shown in the figure)
The generated power is supplied to the load via the power line 2 and the circuit breaker 3. A current transformer 4 and a transformer 5 are installed in the power supply line 2, and detection signals from the current transformer 4 and the transformer 5 are supplied to a power factor detector 6. This power factor detector 6 detects the power factor COSφ of the synchronous generator 1 based on the detection signals of the current transformer 4 and the transformer 5, and supplies the value to the automatic power factor adjustment circuit 7. The automatic power factor adjustment circuit 7 adjusts the actual power factor coSφ detected by the power factor detector 6 to a preset power factor COSφ.
A pulsed drive current is supplied to the electric motor 8a of the electric voltage setting device 8 so that the voltage is S. The electric voltage setting device 8 is
The slider of the variable resistor 8b is rotated in both forward and reverse directions by an electric motor 8a, and the set voltage output from the variable resistor 8b is supplied to an AVII (automatic voltage regulator) 9. The AVR 9 is for controlling the field current supplied to the field coil 1b of the synchronous motor 1 according to the set voltage.

In such a configuration, the automatic power factor adjustment circuit 7
As shown in the figure, the preset power factor COSφS
and each f1't. of the actually detected power factor COSφ. Phase ff
Calculate the difference Δφ (1φS−φ) of 1, and calculate its absolute value 1△φ
1 is lower than the reference value r1 which changes in a sawtooth pattern with a constant period of 1'' (constant slope), J3 is applied and the drive current is output. That is, a pulsed drive current having a duty ratio corresponding to the value of the analog quantity 1Δφ] is supplied to the electric motor 8a of the voltage setting device 8. In this case, each phase angle φS
The polarity of the drive current is switched depending on the magnitude relationship between and φ.

As a result, the motor 8a of the voltage setting device 8 is driven forward or reverse so that 1△φ1 is always minimized, and the AVR
By increasing or decreasing the set voltage for AVR.
9 controls the field current supplied to the field coil 1b, and as a result, the synchronous motor I operates so that the power factor COSφ always becomes the preset power factor COSφS.

``Problems to be Solved by the Invention'' By the way, in the conventional dual automatic power factor adjustment device, the set power factor COSφS and the actually detected power factor COS
The motor 8a of the voltage setter 8 is intermittently driven at a duty ratio according to [absolute value of the difference in each phase angle of Sφ] Δφ, and the set voltage to be supplied is changed stepwise to 0 to AVfl9. By doing so, the field current supplied from 3 4 AV.R9 to the field coil 1b was controlled. However, the absolute value] △
The reference value r, which is used as a reference when determining the duty ratio according to φj, always changes with a constant period T1, that is, with a constant slope, so the output current 1 of the synchronous generator 1 does not provide sufficient responsiveness. Therefore, there is a problem in that it takes a long time for the actual power factor to reach a preset value. For example, if the output current of synchronous generator 1 is the specified value, even if a sufficient response is obtained, if the output current is 1/2 of the specified value, the control amount will be large. In other words, the driving time of the electric motor 8a of the voltage setting device 8 becomes too long, resulting in a large overshoot, and as a result, it takes a long time to settle.

This invention was made in view of the above-mentioned circumstances, and by constantly performing optimal control according to the output current of the synchronous generator, it is possible to reduce the settling time until the actual power factor reaches a preset value. The purpose of the present invention is to provide an automatic power factor adjustment device that can reduce the power factor.

"Means for Solving the Problems" The present invention provides a voltage setting device in which a set voltage output from a variable resistor is increased or decreased by moving a slider of the variable resistor to an electric motor. , field current control means for controlling a field current supplied to the field coil of the synchronous generator according to the set voltage output from the voltage setting device, and detecting the output current and output voltage of the synchronous generator. a detection means, a value corresponding to the power factor of the synchronous generator obtained based on the detection result of the detection means, and a duty ratio according to the difference between a preset value, and and control means for intermittently driving the field current control means and stepwise changing the set voltage supplied to the field current control means, the control means controlling the output current of the synchronous generator obtained by the detection means. The present invention is characterized in that the intermittent drive cycle of the electric motor of the voltage setting device is changed depending on the voltage setting device.

"Operation" According to the above configuration, depending on the output current of the synchronous generator,
Since the intermittent drive cycle of the motor of the voltage setting device changes, the power factor control, that is, the driving time of the motor of the voltage setting device, is adjusted depending on the magnitude of the output current, and this is achieved to ensure optimal control at all times. will be carried out.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, IO is the desired set power factor COSφ
A phase angle setter for setting the phase angle φS of S,
Outputs setting data (digital signal of predetermined bits) corresponding to the phase angle φS.

II is a phase angle detector that detects the phase angle φ of the power factor COSφ of the synchronous generator I based on the detection signals of the current transformer 4 and the transformer 5, and outputs an analog signal corresponding to the phase angle φ. A current detector 12 detects the output current l of the synchronous generator 1 based on the detection signal of the current transformer 4, and outputs an analog signal corresponding to the output current l. These setting data corresponding to the phase angle φS and analog signals corresponding to the phase angle φ and the output current i are supplied to the control circuit l3.

This control circuit 13 includes a CPU (central processing unit) 14,
A ROM (read only memory) 15 that stores control programs used by the CPU 14, a RAM (random access memory) 16 that is used as a work area, and an I/O (input/output) that exchanges various data.
A circuit 17 and an A/D that converts an analog signal corresponding to a phase angle φ and an output current i into a digital signal of a predetermined pit.
It is composed of converters l8 and l9, and a driver 20 that supplies a drive current to the motor 8a of the voltage setting device 8 in accordance with instructions from the CPU 14.

In the above configuration, the control device I3 operates based on the flowchart shown in FIG. That is, step S
In PI to SP3, a preset phase angle φS,
The actually detected phase angles φ and output current i are input in sequence, and in the next step SP4, the absolute value 1Δφ1 of the difference between each phase angle is calculated. Next, if this value 1Δφ1 is 8 greater than the constant value C, step SP5 to next step S
I) Proceed to step 6, and if it is less than the constant value C, it is regarded as a dead zone and return to the original step SPI.

Then, in step SP6, a reference value r whose slope changes in accordance with the output current i of the synchronous generator 1 and changes in a sawtooth shape is sequentially calculated. That is, as shown in FIG. 3, when the output current i is small, the reference value r changes in a sawtooth shape with a period T1, and the slope becomes large; conversely, when the output current i is large, the reference value r changes as follows. It changes in a sawtooth shape with a period T2 (>'. ["l), and its slope becomes small. This step SP
Every time the reference value r is calculated in step 6, the reference value r and 1Δφ{ are compared in the next step SP7, and 1Δφ1〉r
If so, in the next step SP8, the set phase angle φS and the actual phase angle φ are compared, and if φS>φ, the process advances to step SP9, where the driver 20 directs the motor 8a to the motor 8a. drive current is supplied.

If φs is smaller than φ, the process proceeds to step SPIO, and a negative drive current is supplied from the driver 20 to the electric motor 8a. Also, in step SP7 above, 1Δφ1≦
If it is r, proceed to step SPI+, and the electric motor 8
The supply of drive current to a is stopped. This results in
The polarity of the drive current is switched according to the magnitude relationship between the set phase angle φS and the actual phase angle φ, and always) Δφ
The electric motor 8a of the voltage setting device 8
is driven forward or reverse, and the set voltage for the AVR 9 is increased or decreased.

By the operation of the control circuit l3 described above, as shown in FIG. A driving current of 100 m is supplied to the electric motor 8a of the voltage setting device 8, and in this case, the slope of the reference value r, which changes in a sawtooth shape, changes depending on the magnitude of the output current i, and the pulse width of the driving current, that is, Since the driving time of the electric motor 8a is reduced,
Even when the output current i changes, sufficient responsiveness is obtained and optimal control is always achieved.

"Effects of the Invention" As explained above, according to the present invention, the intermittent drive cycle of the motor of the voltage setting device is changed according to the output current of the synchronous generator, so that the magnitude of the output current can be changed. depending on,
The power factor control amount, that is, the driving time of the electric motor of the voltage setting device is adjusted, thereby achieving the effect that optimal control is always performed and the settling time can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a flow chart for explaining the operation of the same embodiment, and FIG. 3 is a waveform diagram for explaining the operation of the same embodiment.
FIG. 4 is a block diagram showing the configuration of a conventional automatic power factor adjustment device, and FIG. 5 is a waveform diagram for explaining the operation of the automatic power factor adjustment device. I1... Phase angle detector, 12... Current detector, 13... Control circuit (control means).

Claims (1)

[Scope of Claims] A voltage setting device in which a set voltage outputted from the variable resistor is increased or decreased by moving a slider of the variable resistor using an electric motor; and a setting voltage outputted from the voltage setting device. field current control means for controlling the field current supplied to the field coil of the synchronous generator according to the detection means; a detection means for detecting the output current and output voltage of the synchronous generator; and a detection result of the detection means. The electric motor of the voltage setting device is intermittently driven at a duty ratio according to the difference between the value corresponding to the power factor of the synchronous generator obtained based on the power factor and a preset value, and the field current control means control means for changing in stages the set voltage supplied to the voltage setting device, the control means controlling the voltage of the motor of the voltage setting device according to the output current of the synchronous generator obtained by the detection means; An automatic power factor adjustment device characterized by changing the intermittent drive cycle.