JPS6127976B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant frequency and constant voltage power generation device for a self-excited induction generator.

As is well known, for example, as described in the Journal of the Institute of Electrical Engineers of Japan (September 1960 issue, page 8), a self-exciting induction generator will not establish a voltage unless the residual voltage is above a predetermined value. When starting power generation, it will not generate power unless there is no load or light load.

In general, the residual voltage of an induction generator decreases significantly due to overload or short circuit, making the self-excitation phenomenon unstable, and the external characteristics of induction generators are generally significant drooping characteristics, so electric motors and incandescent light bulbs cannot be used. When connected as a load, power generation may be stopped if there is a momentary overload such as when starting or lighting.

Therefore, in order to solve this problem, two methods were considered: one is to connect an excitation capacitor between the stator windings, and the other is to cut off the load until the residual voltage exceeds a certain value during electromotive force.

The circuit shown in Figure 1 has an excitation capacitor connected between the output windings of the stator.
1 is a driving prime mover, 2 is a self-exciting induction generator directly connected to the driving prime mover 1, and a rotor (not shown)
has the same structure as a normal squirrel cage induction motor. On the other hand, the stator is equipped with two-phase output windings 2a and 2b and a control winding 2c that is electrically shifted by approximately 90 degrees. 4 is connected. Further, the drive motor 1 is provided with a frequency detector 5 and a servo mechanism 6 for detecting the output frequency of the self-exciting induction generator 2 and correcting the output frequency to a constant value. This servo mechanism 6 is configured to adjust the governor of the drive motor 1 to change the rotational speed of the drive machine 1, thereby keeping the output frequency constant. 7 is a control reactor connected in series to the control winding 2c of the self-exciting induction generator 2, 8 is a thyristor that controls the current flowing through this reactor 7, and 9 is an automatic voltage regulator (hereinafter abbreviated as AVR as appropriate) ), its output side is connected to the thyristor 8, and its input side is connected to the self-exciting induction generator 2.
It is connected to the output side of the output windings 2a and 2b. 10 Hashiya disconnector.

Next, the operation will be explained. In Figure 1,
Assuming that a control current flows through the control winding 2c via the reactor 7, this current flows through the control winding 2c.
Since the current lags by 90° with respect to the output winding 2
This is the same as connecting a resistive load with a power factor of 1.0 to a and 2b. Therefore, if the reactor current is controlled according to the increase or decrease in the load 3 of the self-exciting induction generator 2, constant load control of the self-exciting induction generator 2 can be achieved. Furthermore, since a load 3 with a lagging power factor is generally connected to the load 3 of the generator 2, the output voltage also changes as the load 3 increases or decreases. Therefore, constant voltage control can be performed by detecting the voltage at the output terminal with the automatic voltage regulator 9 and controlling the reactor current of the control winding 2c. Since this constant load control is also used as constant voltage control and is not a complete constant load control, the rotation speed of the driving prime mover 1 changes slightly. Therefore, in order to compensate for this variation in rotation speed, the output frequency of the generator 2 is detected by the frequency detector 5, and the governor is adjusted by the servo mechanism 6.
The rotational speed of the prime mover 1 is varied to keep the output frequency constant.

Further, as the shield breaker 10 shown in FIG. 1, a current-operated shield breaker having time-limited tripping characteristics and instantaneous tripping characteristics is used.

In the conventional constant frequency constant voltage generator, when there is no load, a control current equivalent to the full load of the self-exciting induction generator 2 is passed through the reactor circuit of the control winding 2c in advance, so the voltage feedback system is opened or the AVR9 Interruption of the control current due to a failure of the output thyristor 8 or the like immediately causes overvoltage in the generator 2, leading to failure, dielectric breakdown, or burnout of the generator 2 and load 3. Furthermore, as is well known, the short-circuit current of the self-exciting induction generator 2 attenuates quickly, so the short-circuit failure point cannot be removed with the normal overcurrent operation only, and the short-circuit failure point cannot be removed, and furthermore, the load short-circuit can be removed instantly. There was a problem that if this could not be done, it would lead to a power outage.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and is a constant-frequency constant-voltage power generation device that has a generator and a time-limited tripping characteristic for load protection at the time of overload. In addition, a voltage detection relay is installed to detect low voltage and overvoltage, and by detecting overvoltage with this voltage detection relay,
A signal is sent to the servo mechanism for adjusting the governor of the driving motor to reduce the rotation speed to protect against overvoltage, and the overvoltage signal is used to cut off the load for protection. By detecting a low voltage with the voltage detection relay, a load is connected in series with a resistor to secure a power source for the voltage detection relay and a tripping power source for the breaker,
A constant-frequency constant-voltage device that instantly trips the breaker to protect the generator and load, and also connects a resistor in series with the load to improve the load power factor and prevent the generator from stopping. It is a power generation device.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, reference numeral 11 denotes a cutter that protects the generator 2 from overload and has a time-limited tripping characteristic for load protection. 11a is the above-mentioned breaker 11
This is a voltage trip coil. Reference numeral 12 denotes a voltage detection relay that detects low voltage and overvoltage, and its control power is supplied from the power supply side of the resistor 15 that is connected when the voltage is low, and the low voltage and overvoltage detection section is connected to the load side of the resistor 15. ing. In addition, the overvoltage output of this voltage detection relay 12 is transmitted to the driving motor 1.
The rotation speed is input to the servo mechanism 6 that controls the rotation speed regulating governor, and the rotation speed is lowered to protect the generator 2.
Further, an auxiliary electromagnetic switch 13 for overvoltage detection is connected to the output part of the voltage detection relay 12, and in the event of an overvoltage, the disconnector 11 is tripped by its normally open contact 13a to disconnect and protect the load. Furthermore, a low voltage detection auxiliary switch 14 is also connected to the output part of the voltage detection relay 12, which detects low voltage during heavy loads and short circuits. The normally closed contact 14b secures the trip power supply, advances the load power factor, and prevents power generation from stopping.
The circuit breaker 11 is tripped to remove the heavy load and the tangled point. 15 is a resistance. Incidentally, since the other configurations are the same as the conventional one, the same constituent parts are given the same reference numerals, and the explanation of the other reference numerals will be omitted.

The operation of the device configured as above will be explained.
In the event of overload, a spool or disconnector 11 with time-limiting characteristics is used.
The main circuit is opened to protect the load 3 and the self-exciting induction generator 2. Since the output voltage decreases when a heavy load or a short circuit occurs on the load side of the shield breaker 11, this low voltage is detected by the voltage detection relay 12, the auxiliary electromagnetic switch 14 is operated, and a resistor is connected in series with the load 3. 15 is connected to advance the load power factor to prevent power generation from stopping, and to secure power for the voltage detection relay 12 and the voltage trip coil 11a of the shield breaker 11. At the same time, the normally closed contact 14b of the voltage detection relay 12 trips the disconnector 11 to disconnect the load 3.
Protect generator 2 and load 3. In addition, in the event of overvoltage, the voltage detection relay 12 sends a rotation speed control signal to the servo mechanism 6 that controls the rotation speed adjustment governor of the driving prime mover 1 to lower the rotation speed and suppress the overvoltage of the generator 2. The overvoltage signal from the voltage detection relay 12 operates the auxiliary electromagnetic switch 13 to close the normally open contact 13a, energize the voltage trip coil 11a of the shield breaker 11, trip the shield breaker 11, and start the generator. 2 and load 3.

In addition, although the above embodiment describes the case of a switch or a disconnector, other switching devices having a thermal relay or the like that operates under overload and a trip mechanism may be used, and the same effects as in the above embodiment can be obtained. .

Of course, this invention can also be applied to a three-phase system.

As described above, according to the present invention, a voltage detection relay that detects overvoltage and undervoltage, a self-exciting induction generator at the time of overload, and a sag breaker having a time-limited tripping characteristic for load protection can be replaced with conventional ones. Installed in a constant frequency constant voltage power generator, when a voltage detection relay detects a low voltage such as a heavy load or short circuit, it connects the load in series with a resistor, suppresses the voltage drop on the power supply side, advances the load power factor, and stops power generation. This output signal prevents the overvoltage from occurring, trips the cutter and disconnector to eliminate heavy loads and short circuit points, provides sufficient protection for the self-exciting induction generator against the load, and detects overvoltage with the voltage detection relay. This has the effect of controlling the rotational speed of the driving prime mover, lowering the voltage of the self-exciting induction generator, and cutting off the load to protect the generator and load, resulting in constant frequency and constant voltage power generation.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of a conventional constant frequency constant voltage power generation device of a self-exciting induction generator. FIG. 2 is an electric circuit diagram showing an embodiment of a constant frequency constant voltage power generation device for a self-excited induction generator according to the present invention. In the figure, 1 is a driving prime mover, 2 is a self-exciting induction generator, 2a and 2b are output windings, 2c is a control winding, 3 is a load, 4 is a self-exciting capacitor, and 5 is a self-exciting induction generator.
1 is a servo mechanism, 7 is a reactor, 8 is a thyristor, 9 is an automatic voltage regulator, 10 is a conventional shield disconnector for overcurrent and short circuit protection, and 11 is a shield disconnector with time-limited tripping characteristics for overload protection. 11a is a voltage trip coil, 12 is a low voltage and overvoltage detection relay, 13 is an auxiliary electromagnetic switch for overvoltage detection, 13a
14 is a normally open contact, 14 is a voltage detection relay low voltage detection auxiliary electromagnetic switch, 14a is a normally open contact, 14b is a normally closed contact, and 15 is a resistor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Wind an output winding on the stator of a self-exciting induction generator that is directly connected to the drive motor, and a control winding that is electrically offset by 90 degrees from this output winding. A capacitor is connected in parallel to the output winding. A series circuit consisting of a reactor and a thyristor is connected in series to the control winding, and an automatic voltage regulator that controls the phase of the thyristor according to the output voltage of the output winding is connected to the control winding. , a self-exciting induction generator that controls the rotational speed of the driving prime mover by providing a servo mechanism that detects the output voltage and inputs a detection signal; A circuit breaker having a time-limited tripping characteristic for overprotection is connected in series between the output winding and the load, and a voltage detection relay for detecting overvoltage and undervoltage is connected when the control power source is low voltage. The low voltage and overvoltage detection section is connected to the load side of the resistor, and the overvoltage output is connected to the servo mechanism. A self-exciting induction generator with constant frequency and constant voltage power generation equipment.