JPS59181920A - Generating system using induction machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a power generation system using an induction machine for obtaining stable electrical energy from unstable mechanical energy supplied from an external power source.

[Prior art and its problems]

Connect the induction motor to a power supply with a constant frequency and voltage, such as a commercial power system, and use external power to rotate the rotor of the stainer motor at a rotational speed higher than the synchronous speed, that is, so that the slippage is negative. And this is what I'm being invited to do. However, in the above-mentioned power generation method, the AC separate source that supplies the magnetizing current must be connected to the induction generator, so the generator cannot be operated by itself, and if this AC separate power supply goes out, it will be unable to generate electricity. . In addition, the rotational speed of this induction generator must exceed the synchronous rotational speed determined by the frequency of the separate AC power supply that supplies the magnetizing current in order to generate electricity, and this separate AC power supply requires reactive power for excitation. There are drawbacks.

On the other hand, small-scale hydropower generation and power generation that utilizes natural phenomena such as wind and wave power are often used independently in inconvenient areas such as remote islands and mountainous areas, so commercial power is generally available for the above-mentioned AC power sources. It is difficult to generate electricity unless it is obtained. Also, because natural phenomena are highly variable, the rotational speed of the generator will also change significantly, so even if this generator can be connected to commercial power, during periods below the synchronous rotational speed it will be easy to generate electricity and require little maintenance. Induction generators may not be available.

As a way to overcome the above-mentioned drawbacks of induction generators, there is also a power generation method in which a capacitor is connected to this generator, and the generator self-excites itself due to the reactive current generated by this capacitor, becoming a self-excited generator. However, there are many practical problems, such as large voltage changes due to load fluctuations and a narrow range of rotational speeds that can generate electricity.

[Purpose of the invention]

The present invention provides an induction motor that can generate power independently without requiring a separate AC power source for excitation, and that can generate stable power over a wide rotational speed range from extremely low rotational speeds to high speeds. The purpose is to provide a power generation system using

[Key points of the invention]

This purpose, according to the present invention, is to provide an induction machine driven by an external power source and a stator of the induction machine in order to obtain stable electrical energy from unstable mechanical energy supplied from an external power source. A self-excited inverter that is interposed between the winding and the DC circuit and guides an exciting current from the DC circuit side to the induction machine and also guides the generated energy generated by the induction machine to the DC circuit side. A DC power source that is connected in parallel through a reverse blocking diode and supplies initial energy to the DC circuit for power generation and excitation of the induction machine, and a self-excitation inverter that controls the frequency of the self-excitation inverter according to the rotation speed of the induction machine. This is achieved by including a control device that controls the output voltage of the inverter.

[Embodiments of the invention]

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

In FIG. 1, reference numeral 1 denotes a prime mover, to which an induction generator 2 and a speed detection generator 3 are coupled.

4 is a transistor inverter, and the AC side terminal of this transistor inverter 4 is connected to the armature of the induction generator 2.The DC side terminal of the transistor inverter 4 is connected to a smoothing capacitor 5, a load 6, and a load switch. A series circuit of 7 and a series circuit of a DC power supply 8 and a blocking diode 9 are connected to each other. 12 is a command for the amount of power generation, 13 is a slip adjustment unit, and 14 is an addition point, and from this addition point 14, a voltage corresponding to the frequency of the inverter 4 obtained by subtracting the slip from the rotational speed of the induction generator 2 is obtained. is output. 16 is a φ pattern generator that determines the relationship between the frequency and voltage of this inverter 4, and 17 is a V/F converter that converts the voltage corresponding to this frequency into a frequency. Reference numeral 18 is an addition point where the output of the turn generator 16 and the induction generator 2 are
The AC voltage detected by the instrument transformer 21 connected to the terminal of the AC voltage is compared with the DC voltage converted by the rectifier 22. 6 is a voltage regulator, 26 is a pulse modulator, 27 is a pulse amplifier, and 2 is a pace drive circuit.

Referring to FIG. 1, the present invention will now be described in detail.

When the induction generator 2 is driven by the prime mover 1, a voltage proportional to the rotational speed of the generator 2 is outputted from the speed detection generator 3 and applied to the addition point 14.

On the other hand, the power generation amount command 12 is set externally by a power generation amount setting device or created internally by linking to the rotation speed, etc.
The sliding adjustment unit 13 controls the amount of power generation by controlling the sliding. The output of this sliding adjustment section 13 is the addition point 1
．． 1. At this addition point 14, the slip component which is the output of the slip υ adjustment section 13 is subtracted from the rotational speed of the power generation amount 2, and the value -1 is inputted to the V/F converter 17, which converts the inverter. Determine the frequency of 4.

If the number of poles of the induction generator is P, the number of revolutions per minute is N, and the slip υ is S, then the inverter frequency F is as follows. However, in the case of a generator, the value of slip S is negative. This slide S is controlled with respect to the rotational speed N of the generator 20 (1
) The frequency of the inverter 40 is determined by the equation.

In addition, in order to stably supply the excitation current of the induction generator 2,
Since it is sufficient to keep the ratio between the terminal voltage of the generator 2 and the frequency of the inverter 4 constant, the transistor inverter 4 is controlled so that the ratio between the output voltage and the output frequency is constant. Keeping the ratio of voltage and frequency constant is 16
The V/F pattern generator 16 generates a voltage command corresponding to the frequency of the inverter 4, and this voltage command is equal to the actual voltage detected by the potential transformer 21 at the summing point 1B. After the value is compared with the DC value converted by the rectifier 22, it is input to the voltage regulator 25.

The output of this voltage regulator section is sent to the pulse modulation section 26.
It is modulated in combination with the inverter frequency which is the output of the 24゛ converter 17, and the pulse amplifier 27 and the base drive circuit 4 control the transformer (2/,) which constitutes the inverter 4 to obtain the desired result. Output voltage and frequency.

The DC power supply 8 is a power supply for giving initial excitation to the generator 2 via the inverter 4, and is no longer needed once the voltage of the generator 2 rises, so a blocking diode 9 is connected in series to the DC power supply 8. In addition, if the voltage of the generator 2 becomes higher than the voltage of the DC power supply 8, the power supply is automatically stopped, so a small power supply capacity of the DC power supply 8 is sufficient. Therefore, as the DC power source, a battery, a small-capacity water-immersed magnet generator, etc. that is rotationally driven together with the main engine can be used.

A load switch 7 is connected in series to the load 6, and when the voltage of the generator 2 becomes higher than the voltage of the DC power supply 8, the switch 7 is closed and power is supplied from the generator 2 to the load 6. be done. When the generator 2 is stopped or the generated voltage is low, this switch 7 is kept open to prevent the DC power source 8 from being consumed. The smoothing capacitor 5 is a capacitor for removing and smoothing DC pulsations.

In this embodiment, a transistor inverter is used as the self-excited inverter, but it goes without saying that an inverter using other semiconductors such as a thyristor may be used.

Furthermore, a so-called vector control method is also possible in which the current of the induction generator is controlled by dividing it into a magnetizing current component and a load current component orthogonal to the magnetizing current component.

〔Effect of the invention〕

Since the self-excited inverter is configured to be connected to the armature of the induction generator, there is no need for a separate AC power source for excitation, making it easy to use an induction generator even in areas where separate AC power sources are difficult to obtain, such as in remote areas in the mountains. can drive. Moreover, since the frequency of the self-excited inverter is controlled to vary according to the generator rotation speed, it is possible to generate electricity over a wide rotation speed range from extremely low rotation speeds to high rotation speeds, and the generated power Small hydropower and wind power are especially effective because they can supply high-quality electricity without voltage fluctuations.

Suitable for power generation using wave power, etc. Also, since the DC power supply can only be used for the initial excitation of the generator,
Its power supply capacity may be very small.

In addition, since it is an induction machine with a simple structure and no consumable parts, it is suitable for areas where maintenance is inconvenient, such as in remote areas in the mountains.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1...Motive force, 2...Induction generator, 3...Speed detection generator, 4 - Transistor inverter, 5... Smoothing capacitor, 6... Load, 7 Load switch, 8 DC power supply, 9 - Blocking diode, 12 Power generation command, 13 Sliding adjustment section, 16- V/F pattern generator, 17.VF
Converter, 21... Instrument transformer, 25 - Voltage regulator, 26 - Pulse modulation section, 27 Pulse width device, 28
base drive circuit.

Claims (1)

[Claims] In order to obtain stable electrical energy from unstable mechanical energy supplied from an external power source, an induction machine driven by an external power source, and between the induction machine's stator winding and a DC circuit. A self-excited inverter is interposed in the DC circuit, and is connected in parallel to the DC circuit of the self-excited inverter through a backflow blocking diode. a DC power source that supplies initial energy to a DC circuit for power generation excitation of the induction machine, and a control device that controls the frequency of the self-excited inverter according to the induction machine rotation speed and controls the output voltage of the self-excited inverter. A power generation system using an induction machine comprising