JPS61128770A - Main shaft drive generator system - Google Patents

Abstract

PURPOSE:To enhance the energy conversion efficiency by determining the output waveform by a self-excited inverter, and controlling a constant-voltage output by an automatic voltage regulator, and an output (kW) by a DC voltage regulator. CONSTITUTION:A stationary inverter type main shaft drive generator (S/G) system has a neutral-point led phase double winding main shaft drive synchronous generator 20, a converter 30 for converting the AC output into positive and negative DCs, and a pulse width-modulation/demodulation self-excited inverter 40 for reconverting it to AC of reference frequency reference waveform. Further, an automatic voltage regulator 50 for suppressing the output voltage drop at the load increasing time to hold at the constant voltage, and a controller 60 therefor are provided. Thus, the output waveform is obtained by the inverter 40, the constant voltage output is obtained by the regulator 50, the output (kW) is controlled by the DC voltage regulator in the converter 30, and a drooping characteristic is set by the inverter 40 and the converter 30.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a main shaft drive power generation system used for example on ships, and particularly to a means for removing harmful effects caused by harmonics and a means for improving conversion efficiency.

[Conventional technology]

BACKGROUND ART Recently, stationary inverter-type main shaft drive power generation systems (hereinafter abbreviated as S/G systems) have come into widespread use as power generation systems mounted on ships from the viewpoint of energy saving and low operating costs.

Generally, this type of power generation system eliminates frequency and voltage fluctuations in the generator output due to fluctuations in the rotational speed of the main engine.
The power from the main shaft drive generator is first converted to DC using a converter, and then the DC is reconverted to AC with constant frequency and constant voltage using an inverter.

FIG. 3 is a block diagram showing the basic principle of the S/G system. In the figure, reference numeral 1 denotes a main engine, and a blower fan 3 and a main shaft drive power generator 114 are connected to a rotating shaft of the main engine 1 via a speed change mechanism 2 consisting of, for example, a gear mechanism. A converter 5 is connected to the output end of the main shaft drive generator 4, and converts the output of the main shaft drive generator 4 into direct current.

A silice inverter 7 is connected to the output end of the converter 5 via a beam axle 6, and reconverts the direct current into alternating current of constant frequency and constant voltage and outputs the converted alternating current.

By the DC-AC conversion method using the inverter 7,
They are classified into two types: (1) separately excited inverter S/G systems and (2) self-excited inverter S/G systems.

FIG. 4 shows an example of the above (1) separately excited inverter S/G system. In Fig. 4, 8 is an excitation coil, 9
is a synchronous phase modifier, and 10 is an air breaker. Further, 6a is a DC reactor, and 6b is an AC reactor. In the figure, solid line arrows indicate active power supply paths, and broken line arrows indicate reactive power supply paths. Thus, on the load side of the air breaker 10, an output having a waveform as shown in the boxed area in the figure is obtained.

FIG. 5 shows an example of the automatic inverter S/G system (2). In the figure, 7A, 7B, and 7C indicate inverter devices, and each inverter device is equipped with unit inverters 11.12°13.14 with firing phase angles of 0°, 15°30°, and 45”, respectively. The outputs of these unit inverters 11, 12, 13, and 14 are combined and outputted via a tap transformer 15. 16 is each inverter device 7A, 7B.

A step-up multiple transformer 16 is commonly provided at the output end of 7C, and the output of this step-up multiple transformer 16 is sent to the output bus 17 via the air breaker 10A, 10B, and IOC. . In the figure, the output voltage waveforms of each part are as shown in the boxed parts.

[Problem that the invention seeks to solve]

The (1) separately excited inverter S/G system shown in FIG. 4 has the following problems.

a. Non-self-extinguishing semiconductor (
Specifically, since the synchronous phase modifier 9 is required as a commutation source for the commutating turn-off type thyristor, the energy conversion efficiency is inferior to that of the self-excited type by the amount of energy required to operate the synchronous phase modifier 9.

b. Due to the commutation of the commutated turn-off thyristor, the inverter output contains harmonics. However, most electrical equipment as loads connected to the S/G system are designed based on sine wave input. For this reason, some electrical equipment may suffer from interference due to the above-mentioned harmonics. In order to reduce the harmonic components of the output of the S/G system, the synchronous phase modifier 9 should be made larger in capacity and lower in impedance. However, increasing the size of the synchronous phase modifier 819 results in an increase in operating energy, leading to higher prices and lower efficiency.

The (2) self-excited inverter S/G system shown in FIG. 5 has the following problems.

a. The output waveform of current self-excited S/G systems is essentially a rectangular wave, and harmonics are more likely to cause damage to electrical equipment than in separately-excited systems. In order to make the output waveform of the self-excited S/G system a sine wave, which is the reference input waveform of the majority of electrical devices that serve as loads, a large number of unit inverters 1 are required.
1 to 14, and each inverter device 7A,
It is necessary to provide a step-up multiplex transformer 16 for combining the outputs of 7B and 7C, and it is also necessary to provide a harmonic filter on the AC side. Therefore, it becomes expensive. Furthermore, insertion of the step-up multiple transformer 16 usually causes a loss of about 2 to 3%. By taking measures to improve the waveform in this way,
This results in a decrease in conversion efficiency.

b. In the passive type, the synchronous phase changer 9 can be used as a sustained short-circuit current supply source when the load is short-circuited, so reliable selective cutoff can be performed; however, in the self-excited type, in order to enable selective cutoff, requires special measures and the configuration becomes complicated.

Both self-excited and separately-excited types have various drawbacks, but they are expensive and have low resistance to damage to electrical equipment due to harmonic-containing output waveforms of the S/G system, such as heating, malfunction, and noise. Currently, separately excited types are often used due to the ease of countermeasures.

Recently, the development of self-extinguishing power semiconductor devices such as self-extinguishing thyristors such as GTO thyristors and 81 thyristors, and power transistors has been progressing, and the use of these devices can meet the requirements of S/G systems. It should be possible to meet the required performance to some extent, and if we combine the above-mentioned self-extinguishing power semiconductor device with modulation/demodulation technology, we believe that an automatic S/G system with sine wave output can be realized. It will be done.

The present invention was made based on these circumstances,
The purpose is to provide an S/G system that has a conversion efficiency that is at least higher than that of the current self-excited type, and that can send out a sine wave output whose output waveform does not cause any problems with ordinary electrical equipment.

[Means for solving problems]

The present invention is characterized by taking the following measures in order to solve the above problems and achieve the objects.

In other words, the main shaft drive power generation system of the present invention determines the output waveform with a self-excited inverter using pulse width modulation and demodulation, ensures constant voltage output function with the automatic voltage regulator of the main shaft drive generator, and ensures constant voltage output function with the automatic voltage regulator of the main shaft drive generator. The invention is characterized in that the output (kW) is controlled by the self-excited inverter and the converter, and droop characteristics are set by the self-excited inverter and the converter.

[Effect]

By taking the above measures, a synchronous phase modifier is no longer required, which increases energy conversion efficiency, and also eliminates the need for multiplex transformers for sine wave output, which were required in conventional self-commutated inverters, reducing losses in the transformer. will not occur.

〔Example〕

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention. This example shows a schematic configuration of a high efficiency, low distortion spindle drive power generation system using a stationary self-excited inverter with arbitrary frequency and arbitrary waveform output using pulse width modulation and demodulation technology. As shown in Figure 1, this S/G system:
Neutral point extraction each phase double winding main shaft drive synchronous generation iff (J
:,! , a lower and lower shaft drive generator (abbreviated as below) 20, a converter 30 that converts the AC output from this main shaft drive generator 20 into two types of DC, positive and negative, and two types of DC power supplies, the comparator 930. Output as reference frequency.

A pulse width modulation/demodulation self-excited inverter 40 that reconverts the reference waveform to alternating current, and an automatic voltage that suppresses the output voltage drop within an allowable range and maintains the output voltage constant when the load of the S/G system increases. It consists of a regulator 50 and a control device 60 that controls each of these devices.

FIG. 2 is a block diagram showing in detail one phase of the U phase in FIG. 1. The main shaft drive generator 20 generates an alternating current electromotive force E between the windings 21 and 22 and between the first winding 22 and N points by the rotation of the main engine. The AC electromotive mold is connected between terminals TI and TN as shown in the figure.

Two types of outputs with reversed polarity are taken out between TN-72. The above two types of AC electromotive force E are generated by the converter 30
Rectification is controlled by the commutating turn-off type thyristors 31a to 31d and diodes 328 to 32d, and +E/π (1+C
O5α) is charged as a DC average potential, and -E/ is charged to the capacitor 36 via the DC reactor 35.
It is charged as a DC average potential of π(1+CO5α). Here, α is the commutation turn-off type thyristor 31
This is the control m delay angle of a to 31d. The pulse width modulation/demodulation self-excited inverter 40 includes self-extinguishing semiconductor elements 41 and 42, a low-pass filter 43, and the like. The energization time of the self-extinguishing semiconductor elements 41 and 42 is determined by the pulse width modulation circuit 64 modulating the reference waveform generated by the reference waveform generator 71 using the carrier wave generated by the carrier oscillation circuit 61 of the control device 60. During the energization period, P-
If there is a DC potential difference between Q and Q, a current will flow. At this time, since a low-pass filter 43 is inserted at the inverter output terminal (-M), the reference waveform is Output is retrieved.

The control device 60 is configured as follows. The carrier wave emitted from the carrier oscillation circuit 61 has its waveform shaped by the waveform shaping circuit 62 and is supplied to the pulse width modulation circuit 64 via the buffer 1 circuit 63.

On the other hand, the main bus frequency F applied to the terminal 65 shown in the lower central part of the figure is detected by the frequency sensor 66 and becomes one input of the frequency differential amplifier 67. The other input of the differential amplifier 67 is the reference frequency fo from the terminal 68.
is given. Therefore, the differential amplifier 67 obtains the deviation between the main bus frequency F and the reference frequency fo, and the deviation output is supplied to the function generator 69. Function generator 6
9 determines the frequency of the reference waveform based on the deviation output and the power (kW) of the inverter 40 detected by the output sensor 70, and supplies this to the reference waveform generator 71.

In other words, the frequency differential amplifier 67 and the function generator 71
operates in such a way that the drop in the power generation frequency under load due to the droop characteristic of the spindle drive power generator*20 is reflected in the frequency of the reference waveform.In this way, the output of a predetermined reference waveform is sent from the reference waveform generator 71. , is supplied to the pulse width modulation circuit 64.The pulse width modulation circuit 64 uses the carrier wave generated by the carrier oscillation circuit 61 as described above to generate a predetermined pulse width for the reference waveform generated by the reference waveform generator 71. The output of the pulse width modulation circuit 64 is supplied to an ignition/extinguishing circuit 72. A firing/extinguishing pulse is applied to the gates of semiconductor elements 41 and 42.

Note that the negative feedback circuit 73 corrects disturbances in the regularity of the pulse width modulation waveform due to the power factor of the load.

In addition, a governor switch 74, a pulse/analog converter 7
5, droop controller 76, frequency controller 3
0, current sensor 78, current controller 0-rough 9, and phase controller 80 are circuits for controlling the output of this S/G system, and ultimately control the commutation turn-off type thyristors 318 to 31d of converter 30. By changing the control delay angle α via the ignition circuit 36,
The potential difference between P-Kfm and Q-Kfml is controlled to perform output control. Also, current transformer 81. Voltage actual value sensor 82
The output voltage obtained through the output voltage differential amplifier 83
This is one input. The reference voltage 0 is applied from a terminal 84 to the other input of the differential amplifier 83. Therefore, the differential amplifier 83 outputs a differential voltage between the reference voltage vO and the output voltage, and this differential voltage is supplied to the automatic voltage regulator 50. As a result, automatic voltage regulator 5
Generator 20 world by 0! i If tIO is performed and the output voltage of the S/G system is held constant.

In this way, in this S/G system, pulse width modulation/demodulation technology is used only for waveform formation in the inverter 4o. Therefore, although the harmonic content rate (distortion rate) in the inverter output is improved, the energy conversion efficiency does not decrease. Since it is self-excited, the energy conversion efficiency is high. Furthermore, since there is no need for multiple transformers, which were required in conventional self-excited types, efficiency is high in this respect as well. Since the waveform distortion factor can be determined only by the carrier frequency value, the cutoff frequency value of the low-pass filter 43, and the slope characteristic value of the low-pass filter 43, the main shaft drive generator is suitable for the waveform distortion factor required by the load. It has the advantage of being able to design freely. Further, there is an advantage that outputs of arbitrary frequencies and arbitrary waveforms can be obtained using function generators, reference waveform generators, etc. made up of simple electronic circuits. Furthermore, most of today's electrical equipment is
Since it is designed based on a sine wave input with a frequency of 50 to 6082, if the reference frequency and reference waveform of this S/G system are adapted to these, it will be different from the conventional S/G system.
The problem faced by the G system, namely harmonic interference in electrical equipment, can be almost eliminated.

Note that the present invention is not limited to the above embodiment.

For example, in the above embodiment, a neutral-point-drawing, double-winding, main-shaft drive synchronous power generator 11N20 for each phase is used as the main-shaft drive generator, and a converter 30 that outputs two types of DC power, positive and negative, is used as the converter. Although we have shown the case where a standard waveform such as a sine wave or pulse wave alternating around zero potential is obtained, if it is only necessary to obtain an alternating output with a predetermined bias applied, the main shaft drive A neutral-point-drawing synchronous generator may be used as the generator, a converter that sends out one type of direct current may be used as the converter, and a single-polarity inverter may be used as the inverter. Furthermore, in the above embodiments, the present invention was explained assuming that the present invention is applied to a power supply system for a ship. It is widely applicable to It goes without saying that various other modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

The main shaft drive power generation system of the present invention determines the output waveform with a self-excited inverter using a pulse width modulation/demodulation method, ensures constant voltage output function with an automatic voltage regulator of the main shaft drive generator, and uses a DC potential regulator in the converter to ensure a constant voltage output function. The present invention is characterized in that the output (KW) is controlled and droop characteristics are set between the self-excited inverter and the converter.

Therefore, according to the present invention, there is no need for synchronization phase dawn,
In addition to increasing energy conversion efficiency, the multiple transformer for sine wave output required in conventional self-excited inverters is no longer required, and loss in the transformer is also eliminated. As a result, it is possible to provide an S/G system that has a conversion efficiency that is at least higher than that of the current self-excited type, and that can send out a sine wave output whose output waveform does not cause any problems with ordinary electrical equipment.

[Brief explanation of the drawing]

Figures 1 and 2 show one embodiment of the present invention; Figure 1 shows the schematic configuration of the S/G system, and Figure 2 shows one phase of the U phase in Figure 1. FIG. 3 to 5 are diagrams showing conventional examples, FIG. 3 is a block diagram showing the basic principle of the S/G system, and the fourth factor is a block diagram showing an example of a passive inverter S/G system. FIG. 5 is a block diagram showing an example of a self-excited inverter S/G system. 1... Main engine, 4... Main shaft drive generator, 5... Converter, 7... Inverter, 7A, 7B, 7C...
Inverter device, 8... Excitation coil, 9... Synchronous phase modifier, 16... Step-up multiplex transformer, 20... Neutral point extraction, double winding royal shaft drive synchronous generator for each phase, 30...・Plus/minus two power output converter, 40... Pulse width modulation/demodulation self-excited inverter, 50... Self 1lli!
Pressure regulator, 60...control device.

Claims (1)

[Claims] The output waveform is determined by a self-excited inverter using pulse width modulation and demodulation, the automatic voltage regulator of the main shaft drive generator ensures constant voltage output function, and the DC potential regulator in the converter determines the output waveform (K
W), and droop characteristics are set by the self-excited inverter and the converter.