JPS6318920A - Operation controller of induction machine - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an operation control device for a 4B&.

[Conventional technology]

FIG. 3 is a single-line connection diagram showing an example of a conventional induction motor operation control device. In the figure, 1 is a power source, 2 is a prime mover such as a turbine, 3 is a proar, and 4 is a prime mover 2 that drives the proa 3. If the driving force is insufficient, the electric T!
The induction machine acts as a JJ machine and acts as a generator when the prime mover 2 can provide an output greater than the driving force required by the prower 3. 5 is the load bus.

Next, the operation will be explained. The output of prime mover 2 is Proa 3
When the value is too high, the induction machine 4 rotates at a synchronous speed or higher, acts as a generator, receives reactive power from the power source 1, and generates active power.
supply the load bus to the load bus 5.

On the other hand, when the output of the prime mover 2 is insufficient relative to the proar 3, the induction machine 4 rotates at a synchronous speed or less, so it receives power from the power supply 1 and acts as an electric motor to drive the proar 3.

[Problem that the invention seeks to solve]

Since the conventional induction/machine operation control device is configured as described above, when the induction machine 4 is in the power generation state,
If a temporary voltage drop occurs in the IL source 1 for some reason, the induction machine 4 will not generate electricity because the supply of reactive power will be cut off, and the excessive output of the prime mover 2 will be caused by the overspeed of the rotating shaft. Due to this action, there is a risk of breaking the rotating shaft, and even if temporary breakage does not occur, the prime mover 2 may become overspeed tripped and the blower 3 may also be stopped. In addition, when the induction machine 4 is in an electric operation state, a temporary voltage drop in the power supply 1 will cause the rotation speed to decrease. If the induction motor 4 is not designed with shaft system startup in mind, an excessive current will flow during restart, causing the induction motor 4 to completely burn out. There were some problems, such as the possibility that the

This invention was made to solve the above-mentioned problems, and allows the blower to continue operating by the prime mover even if an instantaneous voltage drop occurs in the power generation state, and also allows the blower to continue operating within a predetermined time in the electric operation state. An object of the present invention is to obtain an operation control device for an induction motor that allows the motor to continue operating after the power is restored in the event of a power outage.

[Failure to solve the problem]

The induction machine operation control device according to the present invention detects and stores the power flow of the induction machine a predetermined time before the voltage drop occurs, and detects the voltage drop of the bus bar to which the induction machine is connected by the detection means. When the induction machine is in the generating state, the turbine governor motor is driven to the down side, and when the induction machine is in the electric state, if the power is not restored within a preset time, the induction machine's power breaker is opened. It has a configuration that outputs a command to.

[For production]

The induction machine operation control device according to the present invention stores the operation mode of the induction machine immediately before the voltage drop, and operates the turbine governor motor when the voltage drops and the induction machine operation mode immediately before the voltage drop is in the power generation state. , the rotation speed of the induction motor is lowered to a predetermined rotation speed, and in the case of an electric state, the induction motor is restarted and operated without opening the power circuit breaker only when the power is restored within a preset time. continue.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the same components as in FIG. 3 are given the same reference numerals, and their explanations will be omitted. In the 11th bus, 21 is a low voltage relay that is a detection means for detecting a voltage drop on the bus bar at high speed, and 22 is a power relay that is a storage means that operates when the generator 4 is operating as a generator. , 23 is a power relay serving as a storage means that operates when the induction machine 4 is operating as a motor, 24 is a speed relay that operates at a speed higher than the maximum possible output when the induction machine 4 is operating as a generator, and 25 is a speed relay. Detector 26 is a control circuit, which is a low voltage relay 21 on the bus bar.
When the low voltage relay 21 operates depending on whether the induction machine 4 is in a generating state or an electric state before operating, the power supply circuit breaker 27 of the induction machine 4 is activated in combination with the speed relay 24.
A command is issued to turn off the turbine governor motor 28 or to decelerate the turbine governor motor 28. Reference numeral 29 denotes an operation control unit whose details are shown in FIG. 2, which includes a contact 21a1 which is operated by the low voltage relay 21, an auxiliary relay 21a1 which is energized when this contact 21a is closed, a contact 21λa1 which is energized when this auxiliary relay 21 hole is operated, and a contact 21λa1 which is the above-mentioned contact. Timer 21T1121T2 that operates when 21a closes, this timer 21TI,
21T2 contacts 26″rlb, 26T2a1 contacts 22a operated by power relays 22, 23 that detect whether the induction motor 4 is in the firing state or in the electric state;
23a.

When the contacts 22a and 23a are closed, the control circuit 26 is energized L/-26X #26Y% The contact 26X1126 is operated by the relays 26X and 26Y
X2 #26X8P26Y1, 26Y2 #26Y8j2
It is composed of 6Y4.

Next, the operation will be explained.

When the induction machine 4 enters the power generation state, the speed is equal to or higher than the synchronous speed. Therefore, the speed is detected by the speed relay 24, but even if the speed relay 24 detects that the synchronous speed is higher than the synchronous speed, it does not necessarily mean that power generation operation is being performed, and the power circuit breaker 2γ of the induction machine 4 is turned off. If the turbine 2 alone rotates the prower 3 slightly faster than the synchronous speed, or if the power supply breaker 27 of the induction machine 4 is on and the bus voltage drops even though it is operating as a generator at or above the synchronous speed. If reactive power suddenly ceases to be supplied from the system, the induction machine 4, which has been operating to generate electricity, will not generate electricity, and the excessive input to the turbine 2 will simply cause the shaft system to overspeed. When the bus voltage drops and the bus voltage returns to its original state (power restoration), a command is issued to the main source interrupter 27 or a command is issued to the turbine governor motor depending on the operating state of the induction machine 4 before the voltage drop. The difference is whether the command is issued to 28 or not. That is, the power relay 22 is operated to detect that the induction machine 4 is in the power generation state, and the induction machine 4 is activated.
When the low voltage relay 21 detects a voltage drop on the bus to which the low voltage relay 21 is connected, the contact 21a is closed, the auxiliary relay 21R is energized, and the auxiliary relay contact 21Ra is thereby closed. Further, since the contact 22a of the power relay 22 is also closed, the relay 26X of the control circuit 26 is energized, and the contact 26X
1.

26X2126Xa is closed. For this reason, relay 2
6X is self-held, and a deceleration command is issued to the turbine governor motor 28 to lower the rotational speed of the turbine 2. In addition,
In this case, the rotational speed is lowered until the speed relay 24 stops operating, in other words, until the speed becomes lower than the maximum possible output speed of the generator. In addition, if it is detected that the electric power relay 23 in the electric state operates and the induction machine 4 becomes electric, a voltage drop occurs, and the configuration is not established even after a predetermined time has elapsed, the timer 21T2 is set. later,
The power supply circuit breaker 27 issues a trigger command.

Further, in the above embodiment, a relay circuit is configured to perform operation control, but a stationary device using a solid state may be used, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the induction motor operation control device detects and stores the power flow of the induction motor a predetermined time before the voltage drop occurs, and the power flow of the induction motor is detected and stored by the sleep relay, A voltage drop is detected by a low voltage relay, and if the induction machine is in a power generation state, the turbine governor motor is driven to the deceleration side, and if it is in an electric state, the power is not restored within a preset time. Since the structure is designed to output a command to open the induction motor's power circuit breaker, even if a voltage drop occurs while the induction motor is in a power generation state, it will not occur due to shaft breakage or overspeed trip due to overspeed of the shaft system. The turbine can be prevented from stopping and the proar can continue to operate, and if the time required to recover after a voltage drop in the electric state is within the allowable value for restarting the motor, the proa load can be operated without burning out the induction machine. This has the effect of expanding the scope of system operation.

[Brief explanation of the drawing]

Fig. 1 is a single line connection diagram showing an operation control device for an induction motor according to an embodiment of the present invention, Fig. 2 is a block diagram showing an extracted operation control section of Fig. 1, and Fig. 3 is a diagram of a conventional induction motor. It is a single line connection diagram showing the operation control section R of. 1 is the power supply, 2 is the prime mover, 3 is the proa, 4 is the induction motor, 21
is a low voltage relay, 22.23 is a power relay, 26 is a control circuit, 27 is a power circuit breaker, and 28 is a turbine governor motor.

Claims (1)

[Claims] An induction machine that acts as an electric motor when the driving force of the prime mover that drives the proa is insufficient, and acts as a generator when the driving force of the prime mover is excessive, and a detection system that detects the voltage drop on the bus bar. storage means for storing the operating mode of the induction machine at a predetermined time before the voltage drop occurs; operation of an induction machine, which is equipped with a control circuit that issues a command to stop the induction machine by opening a power supply circuit breaker if the power is not restored within a preset time and the power supply is not restored within a preset time. Control device.